<title>Abstract</title>
<p>In this study, we evaluated the potential of large language models (LLMs) in the development of educational materials for healthcare professional licensure exams with multiple choice questions (MCQs) in non-English-speaking countries, focusing on Japan's Radiological Technologist National Exam. We adapted MCQs from the exam, categorizing them into image-based, calculation, and textual questions, and generated explanatory texts using Microsoft Bing's Copilot. We assessed the quality of explanatory texts on a 0–4-point scale. Our findings showed that LLMs scored highly in text-based questions, demonstrating strong capabilities in processing textual information. However, we identified significant challenges in formula construction and the calculation process associated with calculation questions. Additionally, despite LLMs' multimodal functions, image-based questions received lower scores, which suggests the need for alternative approaches to these questions. In this study, we highlighted the effectiveness of LLMs in creating educational materials for medical licensure exams in non-English-speaking contexts while also noting the challenges in ensuring students' accuracy when they independently used LLM-generated information.</p>

DOI： 10.21203/rs.3.rs-4233784/v1

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11318/mii.41.15

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ultrasound guidance has become the gold standard for obtaining vascular access. Angle information, which indicates the entry angle of the needle into the vein, is required to ensure puncture success. Although various image processing-based methods, such as deep learning, have recently been applied to improve needle visibility, these methods have limitations, in that the puncture angle to the target organ is not measured. We aim to detect the target vessel and puncture needle and to derive the puncture angle by combining deep learning and conventional image processing methods such as the Hough transform. Median cubital vein US images were obtained from 20 healthy volunteers, and images of simulated blood vessels and needles were obtained during the puncture of a simulated blood vessel in four phantoms. The U-Net architecture was used to segment images of blood vessels and needles, and various image processing methods were employed to automatically measure angles. The experimental results indicated that the mean dice coefficients of median cubital veins, simulated blood vessels, and needles were 0.826, 0.931, and 0.773, respectively. The quantitative results of angular measurement showed good agreement between the expert and automatic measurements of the puncture angle with 0.847 correlations. Our findings indicate that the proposed method achieves extremely high segmentation accuracy and automated angular measurements. The proposed method reduces the variability and time required in manual angle measurements and presents the possibility where the operator can concentrate on delicate techniques related to the direction of the needle.

DOI： 10.1007/s13246-024-01397-x

PubMed

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掲載種別：研究論文（学術雑誌）   出版者・発行元：IMEKO International Measurement Confederation  

In addition to being used in hospitals, ultrasound systems are used in many other medical settings such as disaster relief and home care. In these types of settings, it is important to be able to perform a large number of examinations easily and efficiently. Portable ultrasound systems can be used to meet such needs. The evaluation of ultrasound systems has been driven by the development of accuracy control methods used in breast examinations. This study aimed to evaluate the performance of portable ultrasound systems that have not yet been fully investigated. The performance of two ultrasound systems was evaluated using three measures. For physical evaluation, the change in the mean pixel value of the target and the contrast-to-noise ratio were obtained for each ultrasound system. Statistical analyses were performed to compare these measures between the two systems. For visual evaluation, a receiver operating characteristic analysis was performed. The results of the physical and visual evaluations showed no statistically significant differences between the portable ultrasound systems we evaluated and those that are commonly used in clinical practice.

DOI： 10.21014/actaimeko.v12i4.1382

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11318/mii.40.56

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOS Press  

BACKGROUND: Imaging examinations are crucial for diagnosing acute ischemic stroke, and knowledge of a patient’s body weight is necessary for safe examination. To perform examinations safely and rapidly, estimating body weight using head computed tomography (CT) scout images can be useful. OBJECTIVE: This study aims to develop a new method for estimating body weight using head CT scout images for contrast-enhanced CT examinations in patients with acute ischemic stroke. METHODS: This study investigates three weight estimation techniques. The first utilizes total pixel values from head CT scout images. The second one employs the Xception model, which was trained using 216 images with leave-one-out cross-validation. The third one is an average of the first two estimates. Our primary focus is the weight estimated from this third new method. RESULTS: The third new method, an average of the first two weight estimation methods, demonstrates moderate accuracy with a 95% confidence interval of ±14.7 kg. The first method, using only total pixel values, has a wider interval of ±20.6 kg, while the second method, a deep learning approach, results in a 95% interval of ±16.3 kg. CONCLUSIONS: The presented new method is a potentially valuable support tool for medical staff, such as doctors and nurses, in estimating weight during emergency examinations for patients with acute conditions such as stroke when obtaining accurate weight measurements is not easily feasible.

DOI： 10.3233/xst-230087

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

This study proposes a deep convolutional neural network (DCNN) classification for the quality control and validation of breast positioning criteria in mammography. A total of 1631 mediolateral oblique mammographic views were collected from an open database. We designed two main steps for mammographic verification: automated detection of the positioning part and classification of three scales that determine the positioning quality using DCNNs. After acquiring labeled mammograms with three scales visually evaluated based on guidelines, the first step was automatically detecting the region of interest of the subject part by image processing. The next step was classifying mammographic positioning accuracy into three scales using four representative DCNNs. The experimental results showed that the DCNN model achieved the best positioning classification accuracy of 0.7836 using VGG16 in the inframammary fold and a classification accuracy of 0.7278 using Xception in the nipple profile. Furthermore, using the softmax function, the breast positioning criteria could be evaluated quantitatively by presenting the predicted value, which is the probability of determining positioning accuracy. The proposed method can be quantitatively evaluated without the need for an individual qualitative evaluation and has the potential to improve the quality control and validation of breast positioning criteria in mammography.

DOI： 10.1038/s41598-023-34380-9

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その他リンク： https://www.nature.com/articles/s41598-023-34380-9

記述言語：英語   掲載種別：研究論文（学術雑誌）  

This study aimed to determine the optimal radiographic conditions for detecting lesions on digital chest radiographs using an indirect conversion flat-panel detector with a copper (Cu) filter. First, we calculated the effective detective quantum efficiency (DQE) by considering clinical conditions to evaluate the image quality. We then measured the segmentation accuracy using a U-net convolutional network to verify the effectiveness of the Cu filter. We obtained images of simulated lung tumors using 10-mm acrylic spheres positioned at the right lung apex and left middle lung of an adult chest phantom. The Dice coefficient was calculated as the similarity between the output and learning images to evaluate the accuracy of tumor area segmentation using U-net. Our results showed that effective DQE was higher in the following order up to the spatial frequency of 2 cycles/mm: 120 kV + no Cu, 120 kV + Cu 0.1 mm, and 120 kV + Cu 0.2 mm. The segmented region was similar to the true region for mass-area extraction in the left middle lobe. The lesion segmentation in the upper right lobe with 120 kV + no Cu and 120 kV + Cu 0.1 mm was less successful. However, adding a Cu filter yielded reproducible images with high Dice coefficients, regardless of the tumor location. We confirmed that adding a Cu filter decreases the X-ray absorption efficiency while improving the signal-to-noise ratio (SNR). Furthermore, artificial intelligence accurately segments low-contrast lesions.

DOI： 10.1007/s12194-023-00719-0

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Public Library of Science (PLoS)  

Background

Pulmonary thromboembolism is a serious disease that often occurs in disaster victims evacuated to shelters. Deep vein thrombosis is the most common reason for pulmonary thromboembolism, and early prevention is important. Medical technicians often perform ultrasonography as part of mobile medical screenings of disaster victims but reaching all isolated and scattered shelters is difficult. Therefore, deep vein thrombosis medical screening methods that can be easily performed by anyone are needed. The purpose of this study was to develop a method to automatically identify cross-sectional images suitable for deep vein thrombosis diagnosis so disaster victims can self-assess their risk of deep vein thrombosis.

Methods

Ultrasonographic images of the popliteal vein were acquired in 20 subjects using stationary and portable ultrasound diagnostic equipment. Images were obtained by frame split from video. Images were classified as “Satisfactory,” “Moderately satisfactory,” and “Unsatisfactory” according to the level of popliteal vein visualization. Fine-tuning and classification were performed using ResNet101, a deep learning model.

Results

Acquiring images with portable ultrasound diagnostic equipment resulted in a classification accuracy of 0.76 and an area under the receiver operating characteristic curve of 0.89. Acquiring images with stationary ultrasound diagnostic equipment resulted in a classification accuracy of 0.73 and an area under the receiver operating characteristic curve of 0.88.

Conclusion

A method for automatically identifying appropriate diagnostic cross-sectional ultrasonographic images of the popliteal vein was developed. This elemental technology is sufficiently accurate to automatically self-assess the risk of deep vein thrombosis by disaster victims.

DOI： 10.1371/journal.pone.0282747

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記述言語：日本語   出版者・発行元：(公社)日本放射線技術学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

PURPOSE: Although surgery is the primary treatment for lung cancer, some patients experience recurrence at a certain rate. If postoperative recurrence can be predicted early before treatment is initiated, it may be possible to provide individualized treatment for patients. Thus, in this study, we propose a computer-aided diagnosis (CAD) system that predicts postoperative recurrence from computed tomography (CT) images acquired before surgery in patients with lung adenocarcinoma using a deep convolutional neural network (DCNN). METHODS: This retrospective study included 150 patients who underwent curative surgery for primary lung adenocarcinoma. To create original images, the tumor part was cropped from the preoperative contrast-enhanced CT images. The number of input images to the DCNN was increased to 3000 using data augmentation. We constructed a CAD system by transfer learning using a pretrained VGG19 model. Tenfold cross-validation was performed five times. Cases with an average identification rate of 0.5 or higher were determined to be a recurrence. RESULTS: The median duration of follow-up was 73.2 months. The results of the performance evaluation showed that the sensitivity, specificity, and accuracy of the proposed method were 0.75, 0.87, and 0.82, respectively. The area under the receiver operating characteristic curve was 0.86. CONCLUSION: We demonstrated the usefulness of DCNN in predicting postoperative recurrence of lung adenocarcinoma using preoperative CT images. Because our proposed method uses only CT images, we believe that it has the advantage of being able to assess postoperative recurrence on an individual patient basis, both preoperatively and noninvasively.

DOI： 10.1007/s11548-022-02694-0

PubMed

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その他リンク： https://link.springer.com/article/10.1007/s11548-022-02694-0/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-022-20748-w

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その他リンク： https://www.nature.com/articles/s41598-022-20748-w

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

The convenience of imaging has improved with digitization; however, there has been no progress in the methods used to prevent human error. Therefore, radiographic incidents and accidents are not prevented. In Japan, image interpretation is conducted for incident prevention; nevertheless, in some cases, incidents are overlooked. Thus, assistance from a computer-aided quality assurance support system is important. This study developed a method to identify hand image direction, which is an elementary technology of a computer-aided quality assurance support system. In total, 14,236 hand X-ray images were used to classify hand directions (upward, downward, rightward, and leftward) commonly evaluated in clinical settings. The accuracy of the conventional classification method using original images, classification method with histogram equation images, and a novel classification method using binarization images for background removal via U-Net segmentation was evaluated. The following classification accuracy rates were achieved: 89.20% if the original image was input, 99.10% if the histogram equation image was input, and 99.70% if binarization images for background removal via U-Net segmentation was input. Our computer-aided quality assurance support system can be used to identify hand direction with high accuracy.

DOI： 10.1007/s12194-022-00675-1

PubMed

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その他リンク： https://link.springer.com/article/10.1007/s12194-022-00675-1/fulltext.html

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE  

DOI： 10.1117/12.2624139

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP Publishing  

Abstract

This study investigates the equivalence or compatibility between U-Net and visual segmentations of fibroglandular tissue regions by mammography experts for calculating the breast density and mean glandular dose (MGD). A total of 703 mediolateral oblique-view mammograms were used for segmentation. Two region types were set as the ground truth (determined visually): (1) one type included only the region where fibroglandular tissue was identifiable (called the ‘dense region’); (2) the other type included the region where the fibroglandular tissue may have existed in the past, provided that apparent adipose-only parts, such as the retromammary space, are excluded (the ‘diffuse region’). U-Net was trained to segment the fibroglandular tissue region with an adaptive moment estimation optimiser, five-fold cross-validated with 400 training and 100 validation mammograms, and tested with 203 mammograms. The breast density and MGD were calculated using the van Engeland and Dance formulas, respectively, and compared between U-Net and the ground truth with the Dice similarity coefficient and Bland–Altman analysis. Dice similarity coefficients between U-Net and the ground truth were 0.895 and 0.939 for the dense and diffuse regions, respectively. In the Bland–Altman analysis, no proportional or fixed errors were discovered in either the dense or diffuse region for breast density, whereas a slight proportional error was discovered in both regions for the MGD (the slopes of the regression lines were −0.0299 and −0.0443 for the dense and diffuse regions, respectively). Consequently, the U-Net and ground truth were deemed equivalent (interchangeable) for breast density and compatible (interchangeable following four simple arithmetic operations) for MGD. U-Net-based segmentation of the fibroglandular tissue region was satisfactory for both regions, providing reliable segmentation for breast density and MGD calculations. U-Net will be useful in developing a reliable individualised screening-mammography programme, instead of relying on the visual judgement of mammography experts.

DOI： 10.1088/2057-1976/ac7ada

PubMed

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その他リンク： https://iopscience.iop.org/article/10.1088/2057-1976/ac7ada/pdf

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Background

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity that predominantly occurs in girls. While skeletal growth and maturation influence the development of AIS, accurate prediction of curve progression remains difficult because the prognosis for deformity differs among individuals. The purpose of this study is to develop a new diagnostic platform using a deep convolutional neural network (DCNN) that can predict the risk of scoliosis progression in patients with AIS.

Methods

Fifty-eight patients with AIS (49 females and 9 males; mean age: 12.5 ± 1.4 years) and a Cobb angle between 10 and 25 degrees (mean angle: 18.7 ± 4.5) were divided into two groups: those whose Cobb angle increased by more than 10 degrees within two years (progression group, 28 patients) and those whose Cobb angle changed by less than 5 degrees (non-progression group, 30 patients). The X-ray images of three regions of interest (ROIs) (lung [ROI1], abdomen [ROI2], and total spine [ROI3]), were used as the source data for learning and prediction. Five spine surgeons also predicted the progression of scoliosis by reading the X-rays in a blinded manner.

Results

The prediction performance of the DCNN for AIS curve progression showed an accuracy of 69% and an area under the receiver-operating characteristic curve of 0.70 using ROI3 images, whereas the diagnostic performance of the spine surgeons showed inferior at 47%. Transfer learning with a pretrained DCNN contributed to improved prediction accuracy.

Conclusion

Our developed method to predict the risk of scoliosis progression in AIS by using a DCNN could be a valuable tool in decision-making for therapeutic interventions for AIS.

DOI： 10.1186/s12891-022-05565-6

PubMed

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その他リンク： https://link.springer.com/article/10.1186/s12891-022-05565-6/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IMEKO International Measurement Confederation  

&lt;p class="Abstract"&gt;&lt;span lang="EN-US"&gt;We investigated the relationship between the spatial-resolution property of soft tissue images and the lesion detection ability using U-net. We aimed to explore the possibility of dose reduction during energy subtraction chest radiography. The correlation between the spatial-resolution property of each dose image and the segmentation accuracy of the tumor area in the four regions where the tumor was placed was evaluated using linear regression analysis. The spatial-resolution property was determined by task-based evaluation, and the task-based modulation transfer function (TTF) was computed as its index. TTFs of the reference dose image and the 75 % dose image showed almost the same frequency characteristics regardless of the location of the tumor, and the Dice coefficient also high. When the tumor was located in the right supraclavicular region and under 50 % dose, the frequency characteristics were significantly reduced, and the Dice coefficient was also low. Our results showed a close relationship between the spatial-resolution property and the segmentation accuracy of tumor area using deep learning in dual-energy subtraction chest radiography. In conclusion, a dose reduction of approximately 25 % compared to the conventional method can be achieved. The limitations are the shape of the simulated mass and the use of chest phantom.&lt;/span&gt;&lt;/p&gt;

DOI： 10.21014/acta_imeko.v11i2.1168

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

This study aimed to determine whether a U-Net-based segmentation method could be used to automatically extract regions of the whole heart and atrioventricular regions from pediatric cardiac computed tomography images with high accuracy. Pediatric cardiac contrast computed tomography images with no abnormalities (n = 20; patient age, 0-13 years; mean 5 years) were used for segmentation of the whole heart and each atrioventricular region using U-Net. Segmentation accuracy was evaluated using the Dice similarity coefficient. The mean Dice similarity coefficient for the whole-heart segmentation was high at 0.95. There were no significant differences between age categories. The median Dice similarity coefficients for segmentation of the atria and ventricles were good (> 0.86). There were significant differences between age categories at some sites. Differences in the Dice similarity coefficient may have occurred because the target diseases and examination procedures differed according to subject age. There was no clear tendency for similar values between subjects of school age, close to adulthood, and newborns; good agreement was obtained in all age categories. These results suggest that U-Net-based segmentation may be useful for automatic extraction of the whole heart and atrioventricular regions from pediatric computed tomography images.

DOI： 10.1007/s12194-022-00657-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.21014/acta_imeko.v11i2.1272

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Head computed tomography (CT) is a commonly used imaging modality in radiology facilities. Since multiplanar reconstruction (MPR) processing can produce different results depending on the medical staff in charge, there is a possibility that the antemortem and postmortem images of the same person could be assessed and identified differently. OBJECTIVE: To propose and test a new automatic MPR method in order to address and overcome this limitation. METHODS: Head CT images of 108 cases are used. We employ the standardized transformation of statistical parametric mapping 8. The affine transformation parameters are obtained by standardizing the captured CT images. Automatic MPR processing is performed by using this parameter. The sphenoidal sinus of the orbitomeatal cross section of the automatic MPR processing of this study and the conventional manual MPR processing are cropped with a matrix size of 128×128, and the value of zero mean normalized correlation coefficient is calculated. RESULTS: The computed zero mean normalized cross-correlation coefficient (Rzncc) of≥0.9, 0.8≤Rzncc <  0.9 and 0.7≤Rzncc <  0.8 are achieved in 105 cases (97.2%), 2 cases (1.9%), and 1 case (0.9%), respectively. The average Rzncc was 0.96±0.03. CONCLUSION: Using the proposed new method in this study, MPR processing with guaranteed accuracy is efficiently achieved.

DOI： 10.3233/XST-221142

PubMed

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記述言語：日本語   出版者・発行元：(公社)日本放射線技術学会  

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その他リンク： https://search.jamas.or.jp/default/link?pub_year=2022&ichushi_jid=J01192&link_issn=&doc_id=20220126400003&doc_link_id=1390853741275705216&url=https%3A%2F%2Fcir.nii.ac.jp%2Fcrid%2F1390853741275705216&type=CiNii&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00003_3.gif

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

PURPOSE: Accurate positioning is essential for radiography, and it is especially important to maintain image reproducibility in follow-up observations. The decision on re-taking radiographs is entrusting to the individual radiological technologist. The evaluation is a visual and qualitative evaluation and there are individual variations in the acceptance criteria. In this study, we propose a method of image evaluation using a deep convolutional neural network (DCNN) for skull X-ray images. METHOD: The radiographs were obtained from 5 skull phantoms and were classified by simple network and VGG16. The discrimination ability of DCNN was verified by recognizing the X-ray projection angle and the retake of the radiograph. DCNN architectures were used with the different input image sizes and were evaluated by 5-fold cross-validation and leave-one-out cross-validation. RESULT: Using the 5-fold cross-validation, the classification accuracy was 99.75% for the simple network and 80.00% for the VGG16 in small input image sizes, and when the input image size was general image size, simple network and VGG16 showed 79.58% and 80.00%, respectively. CONCLUSION: The experimental results showed that the combination between the small input image size, and the shallow DCNN architecture was suitable for the four-category classification in X-ray projection angles. The classification accuracy was up to 99.75%. The proposed method has the potential to automatically recognize the slight projection angles and the re-taking images to the acceptance criteria. It is considered that our proposed method can contribute to feedback for re-taking images and to reduce radiation dose due to individual subjectivity.

DOI： 10.6009/jjrt.780104

PubMed

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.measen.2021.100089

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.measen.2021.100127

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掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE  

DOI： 10.1117/12.2581424

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Public Library of Science (PLoS)  

<sec id="sec001"><title>Objective</title>Despite the high risk of missing lesions in mammography, the missed lesion rate is yet to be clinically established. Further, no breast phantoms with adjustable breast density currently exist. We developed a novel, adjustable-density breast phantom with a composition identical to that of actual breasts, and determined the quantitative relationship between breast density and the missed lesion rate in mammography.

</sec><sec id="sec002"><title>Methods</title>An original breast phantom consisting of adipose- and fibroglandular-equivalent materials was developed, and a receiver operating characteristic (ROC) study was performed. Breast density, which is the fraction by weight of fibroglandular to total tissue, was adjusted to 25%, 50%, and 75% by arbitrarily mixing the two materials. Microcalcification, mass lesions, and spiculated lesions, each with unique characteristics, were inserted into the phantom. For the above-mentioned fibroglandular densities, 50 positive and 50 negative images for each lesion type were used as case samples for the ROC study. Five certified radiological technologists participated in lesion detection.

</sec><sec id="sec003"><title>Results</title>The mass-lesion detection rate, according to the area under the curve, decreased by 18.0% (<italic>p</italic>= 0.0001, 95% Confidence intervals [CI] = 0.1258 to 0.1822) and 37.8% (<italic>p</italic>= 0.0003, 95% CI = 0.2453 to 0.4031) for breast densities of 50% and 75%, respectively, compared to that for a 25% breast density. A similar tendency was observed with microcalcification; however, spiculated lesions did not follow this tendency.

</sec><sec id="sec004"><title>Conclusions</title>We quantified the missed lesion rate in different densities of breast tissue using a novel breast phantom, which is imperative for advancing individualized screening mammography.

</sec>

DOI： 10.1371/journal.pone.0245060

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Bedside radiography has increasingly attracted attention because it allows for immediate image diagnosis after X-ray imaging. Currently, wireless flat-panel detectors (FPDs) are used for digital radiography. However, adjustment of the X-ray tube and FPD alignment are extremely difficult tasks. Furthermore, to prevent a poor image quality caused by scattered X-rays, scatter removal grids are commonly used. In this study, we proposed a scatter-correction processing method to reduce the radiation dose when compared with that required by the X-ray grid for the segmentation of a mass region using deep learning during bedside chest radiography. A chest phantom and an acrylic cylinder simulating the mass were utilized to verify the image quality of the scatter-corrected chest X-rays with a low radiation dose. In addition, we used the peak signal-to-noise ratio and structural similarity to quantitatively assess the quality of the low radiation dose images compared with normal grid images. Furthermore, U-net was used to segment the mass region during the scatter-corrected chest X-ray with a low radiation dose. Our results showed that when scatter correction is used, an image with a quality equivalent to that obtained by grid radiography is produced, even when the imaging dose is reduced by approximately 20%. In addition, image contrast was improved using scatter radiation correction as opposed to using scatter removal grids. Our results can be utilized to further develop bedside chest radiography systems with reduced radiation doses.

DOI： 10.1007/s12194-020-00586-z

PubMed

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その他リンク： http://link.springer.com/article/10.1007/s12194-020-00586-z/fulltext.html

記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：新潟医療福祉学会  

type:論文(Article)
【目的】本研究の目的は coronary computed tomography angiography（CCTA）におけるコンピュータ支援診断システムの要素技術として、石灰化またはステントを有する冠動脈と通常の冠動脈の断面像を高精度に自動分類することである。【方法】49 症例の CCTA 画像から再構成した冠動脈の直交断面画像 72,051 枚（石灰化群 13,035 枚、ステント群 14,382 枚、正常群 44,634 枚）を用いた。Deep convolutional neural network（DCNN）には一般に公開されている VGG-16 から畳み込み層を 6 層増やした VGG-22を使用した。この VGG-22 から全結合層の中間層数を 3層から 5 層と増やした。対象画像のうち 64,846 枚を学習データに、7,205 枚をテスト画像に使用した。Holdout 検証を 7 回行い、各群の的中率を算出し、3 種類のDCNN を比較した。【結果】石灰化群の的中率は 3 層では 95.3％、4 層では95.6％、5 層では 95.9％であった。また、ステント群の的中率は 3 層では 99.2％、4 層では 98.9％、5 層では99.3％であった。【結論】DCNN の全結合層を増やすことにより、CCTAを用いた石灰化とステントの自動分類精度を向上させることができる。本研究結果は、CCTA による冠動脈疾患のトリアージに有効である。
Purpose ： The purpose of this study was to classify coronary arteries with calcifications or stents and normal coronary arteries with high accuracy as a computer-aided diagnosis system in coronary computed tomography angiography (CCTA). Methods ： Altogether, 49 CCTA scans were taken retrospectively. We obtained 72,051 cross-sectional images of coronary arteries (13,035 calcified images, 14,382 stent images, and 44,634 normal images) among CCTA images. For the deep convolutional neural network (DCNN), we used VGG-22 with six additional convolutional layers from the publicly available VGG-16. From VGG-22, the number of intermediate layers in the full connected layers were increased from three to five. On the target images, 64,846 images were used as training data, and 7,205 images were used as test images. We performed hold-out validation at seven times, calculated accuracy and positive predictive value of each group, and compared the three DCNNs. Results ： The positive predictive value of the calcified group was 95.3% for 3 full connected layers, 95.6% for 4 layers, and 95.9% for 5 layers. The positive predictive value of the stent group was 99.2% for 3 layers, 98.9% for 4 layers, and 99.3% for 5 layers. Conclusion ： The accuracy of automatic classification with calcifications and stents using CCTA can be improved by increasing the fully connected layer of DCNN. The results show that DCNN is effective for triage of coronary artery disease using CCTA.
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その他リンク： http://id.ndl.go.jp/bib/031224466

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s11604-020-00986-6

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その他リンク： https://link.springer.com/article/10.1007/s11604-020-00986-6/fulltext.html

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE  

This study is aimed to automatically segment mammary gland region into scattered mammary glands and fatty breasts using deep learning method. Total 433 mediolateral oblique-view mammograms of Japanese women were collected and confirmed for scattered mammary glands or fatty breasts; using BI-RADS's classification. First, manually contoured mammary gland regions were determined for all mammograms as ground truths by three certified radiological technologists. Second, the U-net model was employed to segment the mammary gland region automatically. This model is a type of convolutional neural network (CNN) mainly aimed at medical image segmentation. The segmentation accuracies were assessed based on five criteria, Dice coefficients, breast densities, mean gray values, centroids, and sizes of mammary gland region. The Dice coefficient was 0.915. The mean size of mammary gland regions obtained by the Unet was 8.7% larger than that of the ground truths. The mean centroid coordinates of mammary gland regions by the U-net were shifted 1.6 and 5.4 mm on average in mediolateral and craniocaudal directions, respectively from ground truths. The mean gray value of mammary gland regions obtained by the U-net was only 0.4% higher compared with ground truths. The resultant difference was 0.4% on average in breast densities between ground truths and the segmented mammary gland regions. We found significant similarity in the ground truths and the data generated by deep learning on all the parameters, thereby attesting the efficacy of this method for segmenting the mammary gland regions of not only the dense breasts but also the scattered mammary gland- and fatty- breasts.

DOI： 10.1117/12.2562180

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE  

Receiver operating characteristic (ROC) examination was performed to investigate the effectiveness of high-luminance monitors in digital X-ray mammography. For this purpose, an original breast phantom consisting of adipose and fibroglandular equivalent tissues with an identical X-ray absorption characteristic over the entire mammographic photon energy range was developed. Furthermore, the phantom's fibroglandular density and distribution could be changed arbitrarily. Three types of lesions, microcalcification, mass, and spiculated, were inserted into the breast phantom, and the ROC examination was performed by five radiological technologists certified in screening mammography, to obtain the area under the curve. A liquid crystal display (LCD) monitor with 5 megapixels in a 21-inch display size calibrated to a grayscale standard display function curve was used for the observation. The monitor was set to 600, 900, and 1200 cd/m(2) in maximum luminance. The experimental details were fibroglandular density of 25%, respective 50 positive and negative images, and free observation time and distance. As a result, the dependence on monitor luminance differed according to the lesion type. The detectability of microcalcification increased with the increase in the luminance of the monitor. Spiculated lesions were similar for all luminance changes. The detectability of mass lesions was significantly higher at 900 cd/m(2) than at 600 cd/m(2). There was no significant difference between those at 900 cd/m(2) and 1200 cd/m(2). In conclusion, the maximum luminance of the diagnostic LCD monitor for mammography should be at least 900 cd/m(2) to guarantee stable detectability.

DOI： 10.1117/12.2555276

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s11604-019-00894-4

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記述言語：日本語   出版者・発行元：(公社)日本放射線技術学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

DOI： 10.11318/mii.36.98

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その他リンク： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17K17738/

担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

DOI： 10.11318/mii.36.83

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11318/mii.36.64

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1117/12.2507351

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11409/mit.36.217

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.2018_JSRT_74.11.1286

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その他リンク： http://id.ndl.go.jp/bib/029359646

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.6009/jjrt.2018_JSRT_74.10.1138

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1166/jmihi.2018.2398

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.14923/transinfj.2017IGL0001

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技術学会  

DOI： 10.6009/jjrt.2017_JSRT_73.11.1125

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

DOI： 10.11318/mii.34.92

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その他リンク： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16K09012/

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4236/jbise.2017.103009

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11409/mit.36.32

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

<p>The purpose of this study is to investigate and compare the effectiveness of two previously proposed waveletbased medical image enhancement methods,<i> i.e</i>., exponential-type （E-type） and sigmoid-type （S-type） mapping methods. A total of 30 chest radiographs, CT images and mammograms were evaluated visually by using Scheffe's method for paired comparison. As a visual evaluation, images obtained with and without enhancement processing, or images processed with the two enhancement methods were displayed side by side on a light emitting diode monitor. Two different images, <i>i.e</i>.,original image vs. image processed with E-type mapping method, original image vs. image processed with S-type mapping method, and image processed with E-type mapping method vs. that with S-type mapping method, were then evaluated on a discrete rating scale. The experimental results showed that the images processed with S-type mapping method are significantly better than the original images obtained with the three different modalities in both the visual and quantitative evaluations. In addition, the images processed with E-type mapping method are significantly better than the original images of chest radiographs in both the evaluations. The results demonstrate that the previously proposed image enhancement methods are effective and feasible.</p>

DOI： 10.11318/mii.33.63

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

The purpose of this study is to develop an automated selection method for cross‐sectional images with basal ganglia from brain CT scan. The proposed method includes binarization, morphological operation and labeling techniques. Area was calculated from the labeled region inside the cranial bones. The cross‐sectional images with basal ganglia were automatically selected using the calculated area. The method was applied to 22 cases each with 20 slices. As a result, the sensitivity and the specificity were 0.95 and 0.98 respectively. The proposed method would be a fundamental technique for the development of computer‐aided diagnosis（CAD）system.

DOI： 10.11318/mii.33.16

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Tokyo  

The volume of the temporal horn of the lateral ventricle (THLV) on brain computed tomography (CT) images is important for neurologic diagnosis. Our purpose in this study was to develop a z-score-based semi-quantitative analysis for estimation of the THLV volume by using voxel-based morphometry. The THLV volume was estimated by use of a z-score mapping method that consisted of four main steps: anatomic standardization, construction of a normal reference database, calculation of the z score, and calculation of the mean z score in a volume of interest (VOI). A mean z score of the CT value obtained from a VOI around the THLV was used as an index for the THLV volume. CT scans from 50 subjects were evaluated. For evaluation of the accuracy of this method for estimating the THLV volume, the THLV volume was determined manually by neuroradiologists (serving as the reference volume). A mean z score was calculated from the VOI for each THLV of the 50 subjects by use of the proposed method. The accuracy of this method was evaluated by use of the relationship between the mean z score and the reference volume. The quadratic polynomial regression equation demonstrated a statistically significant correlation between the mean z score and the reference volume of the THLV (R2 = 0.94
P &lt
 0.0001). In 92 of 100 THLVs (92 %), the 95 % prediction interval of the regional mean z score captured the reference volume of the THLV. The z-score-based semi-quantitative analysis has the potential quantitatively to estimate the THLV volume on CT images.

DOI： 10.1007/s12194-015-0335-0

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掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Radiological Technology  

CT perfusion (CTP) is obtained cerebrovascular circulation image for assessment of stroke patients; however, at the expense of increased radiation dose by dynamic scan. Iterative reconstruction (IR) method is possible to decrease image noise, it has the potential to reduce radiation dose. The purpose of this study is to assess the visual effect of IR method by using a digital perfusion phantom. The digital perfusion phantom was created by reconstructed filtered back projection (FBP) method and IR method CT images that had five exposure doses. Various exposure dose cerebral blood flow (CBF) images were derived from deconvolution algorithm. Contrast-to-noise ratio (CNR) and visual assessment were compared among the various exposure dose and each reconstructions. Result of low exposure dose with IR method showed, compared with FBP method, high CNR in severe ischemic area, and visual assessment was significantly improvement. IR method is useful for improving image quality of low-dose CTP.

DOI： 10.6009/jjrt.2015_JSRT_71.11.1063

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4236/jbise.2015.810067

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4236/health.2015.76078.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4236/health.2015.72026

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4236/health.2015.71004

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記述言語：日本語   出版者・発行元：(公社)日本放射線技術学会  

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Radiological Technology  

In this paper, we propose a detection method for blurred regions in radiographs. The method involves edge detection using a Sobel filter, manually determining the region of interest (ROI), feature calculation, and classification using a support vector machine. We applied our method to 14 phantom images (7 normal images, 7 blurred images) and 14 clinical images (12 normal images, 2 blurred images). As a result, the average classification accuracies of ROIs with blurring and ROIs without blurring were 98% and 90% for phantom images and clinical images, respectively.

DOI： 10.6009/jjrt.2014_JSRT_70.3.254

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技師教育学会  

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その他リンク： http://search.jamas.or.jp/link/ui/2014238123

担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Radiological Technology  

Objective evaluation, e.g., using the modulation transfer function (MTF) or the noise power spectrum (NPS) of an X-ray imaging system may not correctly correspond to the subject's evaluation, e.g., when using the receiver operating characteristic (ROC). Moreover, it is difficult to measure MTF or NPS from clinical images. We therefore applied MTF fractal dimension to an X-ray imaging system. The MTF fractal dimension includes the frequency properties of the human eye in addition to quantitative complexity. In this study, we demonstrated a relationship between basic image quality and MTF fractal dimension using simulated and actual X-ray images.

DOI： 10.6009/jjrt.2014_JSRT_70.3.250

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer-Verlag Tokyo  

The hyperdense middle cerebral artery (MCA) dot sign representing a thromboembolus is one of the important computed tomography (CT) findings for acute stroke on unenhanced CT images. Our purpose in this study was to develop an automated method for detection of the MCA dot sign of acute stroke on unenhanced CT images. The algorithm of the method which we developed consisted of 5 major steps: extraction of the sylvian fissure region, initial identification of MCA dots based on the morphologic top-hat transformation, feature extraction of candidates, elimination of false positives (FPs) by use of a rule-based scheme, and classification of candidates using a support vector machine (SVM) classifier with four features. Our database comprised 297 CT images obtained from seven patients with the MCA dot sign. The performance of this scheme for classification of the MCA dot sign was evaluated by means of a leave-one-case out method. The performance of the classification by use of the SVM achieved a maximum sensitivity of 97.5 % (39/40) at a FP rate of 1.28 per image. The sensitivity for detection of the MCA dot sign was 97.5 % (39/40) with a FP rate of 0.5 per hemisphere. The method we developed has the potential to detect the MCA dot sign of acute stroke on unenhanced CT images. © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2013.

DOI： 10.1007/s12194-013-0234-1

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Springer Verlag  

The realities of physical and psychological burden associated with mammography are not fully understood. We have measured the muscle activity and the sympathetic nervous activity of subjects during mammography to estimate the burden. The experimental results suggested that positioning during mammography affects the muscle activity and the sympathetic nervous activity of the body. We carried out another preliminary experiment for decreasing the examinee's burden using humorous video. In the experiment, two groups ("humor group" and "neutral group") underwent mammography. The humor group was shown a humorous video during mammography. As a result, numerical rating scale scores of humor group on pain and experience time were higher than that of neutral group (no significant difference). In conclusion, the physical and psychological burden of mammography examinees could be evaluated by measuring the muscle activity and the sympathetic nervous activity. Humorous video may be effective at increasing pain tolerance of subjects during mammography. © 2014 Springer International Publishing.

DOI： 10.1007/978-3-319-07887-8_71

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記述言語：日本語   出版者・発行元：(公社)日本放射線技術学会  

J-GLOBAL

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4236/health.2013.58181

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

In this work, the authors present an effective denoising method to attempt reducing the noise in mammographic images. The method is based on using hierarchical correlation of the coefficients of discrete stationary wavelet transforms. The features of the proposed technique include iterative use of undecimated multi-directional wavelet transforms at adjacent scales. To validate the proposed method, computer simulations were conducted, followed by its applications to clinical mammograms. Mutual information originating from information theory was used as an evaluation measure for selection of an optimal wavelet basis function. We examined the performance of the proposed method by comparing it with the conventional undecimated discrete wavelet transform (UDWT) method in terms of processing time-consuming and image quality. Our results showed that with the use of the proposed method the computation time can be reduced to approximately 1/10 of the conventional UDWT method consumed. The results of visual assessment indicated that the images processed with the proposed UDWT method showed statistically significant superior image quality over those processed with the conventional UDWT method. Our research results demonstrate the superiority and effectiveness of the proposed approach.

DOI： 10.1007/s10278-012-9555-6

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In this work the authors present an effective denoising method to attempt to reduce the noise in mammographic images. The method is based on using hierarchical correlation of the coefficients of discrete stationary wavelet transforms. The features of the proposed technique include iterative use of undecimated multi-directional wavelet transforms at adjacent scales. To validate the proposed method, computer simulations were conducted, followed by its applications to clinical mammograms. Mutual information originating from information theory was used as an evaluation measure in the present study. Moreover, we conducted a perceptual evaluation of the processed images obtained from the proposed method and other conventional methods for confirmation of the effectiveness of the proposed approach. The experimental results show that our proposed method has the potential to effectively reduce noise while maintaining high-frequency information of original images. © 2013 Springer-Verlag.

DOI： 10.1007/978-3-642-29305-4_229

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人電子情報通信学会  

カメラ画像から胸部単純X線画像の領域を自動検出する一手法を提案する.提案法は,主にSIFT特徴量による検出対象の存在判定処理とハフ変換による検出対象の領域抽出処理で構成される.胸部単純X線画像148枚を撮影したカメラ画像に対する検出率は100%となり,提案法の有用性が示された.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

The purpose of this study was to evaluate the performance of a conventional discrete wavelet transform (DWT) method and a modified undecimated discrete wavelet transform (M-UDWT) method applied to mammographic image denoising. Mutual information, mean square error, and signal to noise ratio were used as image quality measures of images processed by the two methods. We examined the performance of the two methods with visual perceptual evaluation. A two-tailed F test was used to measure statistical significance. The difference between the M-UDWT processed images and the conventional DWT-method processed images was statistically significant (P&lt
0.01). The authors confirmed the superiority and effectiveness of the M-UDWT method. The results of this study suggest the M-UDWT method may provide better image quality as compared to the conventional DWT. © 2013 IEEE.

DOI： 10.1109/EMBC.2013.6610272

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

The amount of radiation dose to the patient from digital radiography is of great concern. In particular, it is important to keep the radiation dose exposure to a minimum for patients in their reproductive period, who frequently undergo repeated radiation exposure during the course of diagnostic imaging and treatment follow-up. However, there is a well-recognized trade-off between image quality and radiation dose. The balancing of dose and image quality should be performed explicitly to ensure that patient doses are kept as low as reasonable achievable, while maintaining a clinically acceptable image quality. In response to this issue, many researchers have conducted extensive studies on developing image processing methods. In this paper, we propose an improved wavelet-transform-based method for offering a possibility to reduce the radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates the advantages of our previously proposed wavelet-coefficient weighted method and the existing BayesShrink thresholding method. To verify the effectiveness of the proposed method, we measured and compared the presampled modulation transfer functions and the noise power spectra (NPS) of the processed computed radiography images. Furthermore, variations of contrast and NPS with respect to radiation dose were also examined. Visual evaluations were also performed by five experienced radiological technologists. Experimental results demonstrated that the proposed method could improve the resolution characteristic while keeping the noise level within an acceptable limit. Our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved with the proposed method in hip joint and lumbar spine radiographs. © 2013 Springer-Verlag.

DOI： 10.1007/978-3-642-29305-4_233

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Improving image quality in digital mammographic images has clinical impact in order to increase accuracy of detection of breast cancer. This study aimed to develop and evaluate a new method for denoising mammographic images. The features of the proposed method include iterative use of undecimated multidirectional wavelet transforms at adjacent scales. In this method, computer-based simulations have been carried out for selecting wavelet basis function based on mutual information metric. Perceptual experiments on clinical mammograms were conducted. This new method was compared with the conventional methods to demonstrate its superiority.

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This study presents an improved wavelet-transform-based method for offering a possibility to reduce the radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates a straightforward extension of our previously proposed wavelet-coefficient weighted method and the existing BayesShrink thresholding method. Experimental results demonstrated that the proposed method could improve the resolution characteristic while keeping the noise level within an acceptable limit. Our visual evaluation also showed that an approximately 40% reduction in exposure dose could be achieved with the proposed method in hip joint and lumbar spine radiographs.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TOHOKU UNIV MEDICAL PRESS  

Mammography has become widespread as a standard method for breast cancer screening. For women undergoing mammography, compression of the breast and special positioning are requested, and they cause the physical burden and pain. However, the reality of the physical burden and subjective pain associated with mammography are not fully understood. We therefore measured the muscle activity of subjects during positioning for mammography screening using surface electromyography to evaluate the physical burden and pain associated with the positioning. The subjects consisted of 15 women (age: 44.4 +/- 6.56 years old, height: 160 +/- 6.7 cm, weight: 55.08 +/- 3.94 kg, and body mass index: 21.4 +/- 2.21). Measurements were performed in the mediolateral oblique position, a standard position for mammography. The target muscles were the sternocleidomastoid, biceps, trapezius and gastrocnemius muscles. A portable multi-purpose bio-amplifier was used for the measurements. Visual analogue scale (VAS), which is a tool for self-assessment of subjective pain, was used for pain measurement. The analysis of variance showed the significant difference in the amounts of muscle activities in all the target muscles between the relaxation phase before mammography positioning and the stress phase during mammography positioning. The sites with the increased muscle activities were consistent with the sites of pain measured with the VAS. These results suggest that positioning during mammography affects the muscle activity and that the increased muscle activity could be related to the pain. Understanding muscle activities during mammography is invaluable in making the pain reduction program for the subjects undergoing mammography.

DOI： 10.1620/tjem.228.53

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

In Japan, radiologists and radiologic technologists are endeavoring to improve the quality of lung CT screening. In particular, preliminary screening by radiologic technologists is expected to decrease radiologists' burden and improve the accuracy of CT screening. We considered that an application of computer-aided detection (CAD) would also be as useful in preliminary screening as in the radiologist's regular reading. Our purpose in this study was to investigate the potential of the application of CAD to preliminary screening. CAD software that we developed was applied to 17 lung CT scans that radiologic technologists had pre-interpreted. A radiologist recognized 29 lung nodules from the CT images, whereas radiologic technologists did not recognize 11 of the 29 nodules at their pre-reading. Our CAD software detected lung nodules at an accuracy of 100% (29/29), with 4.1 false positives per case. The 11 nodules that radiologic technologists did not recognize were included in the CAD-detected nodules. This result suggests that the application of CAD may aid radiologic technologists in their preliminary screening. © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2012.

DOI： 10.1007/s12194-012-0145-6

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

本研究では,ディジタル医用X線画像の画質改善と被ばく線量低減を目的として,ウェーブレット変換に基づく画像処理の一手法を提案する.本提案手法はウェーブレット展開係数変換曲線とBayes Shrink法の組合せによる複合型ウェーブレット変換法である.本提案手法による処理後の画像の物理特性の結果では,画像の解像特性を向上させつつノイズを抑制し,さらに,コントラストをも強調させる特性があり,画質を改善させることを示した.視覚評価の結果から,本提案手法を用いることで,画像の画質を落とさずに,生殖腺近傍の撮影領域に対して,約5割程度の被ばく線量低減効果を認めた.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Our purpose in this study was to develop a computer-aided detection scheme for identification of hypoattenuation of acute stroke on unenhanced CT images to select patients for thrombolysis of acute stroke. This method is based on a z-score mapping method. The algorithm of the developed method consisted of five main steps: anatomic standardization, calculation of the z-score with a normal reference database, extraction of candidate voxels for hypoattenuation, feature extraction, and classification. The territory of the middle cerebral artery was divided into ten specified regions, according to a visually quantitative CT scoring system, the Alberta Stroke Programme Early CT Score (ASPECTS) method. Each of the ASPECTSdefined regions was classified as hypoattenuation or normality by linear discriminate analysis. The method was applied to 26 patients who had hypoattenuation areas (&lt
6 h). The performance of this scheme for classification of hypoattenuation was evaluated using a leave-one-case-out method. As a result, an average sensitivity of 89.7% and an average specificity of 85.2% for automatically classifying hypoattenuation regions in the lentiform nucleus and the insular regions were obtained, and the average accuracy for the classification of hypoattenuation per patient was 84.6% (range 55.6-100%). The newly developed method has the potential accurately to identify hypoattenuation of acute stroke in the ASPECTS-defined regions. © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2011.

DOI： 10.1007/s12194-011-0143-0

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

The purpose of this study was to measure muscle activity in mammography positioning using surface electromyography. The subjects consisted of 15 females in their 30s-50s, and measurement was performed with positioning for mediolateral oblique view and cranio-caudal view. The sternocleidomastoid, biceps brachii, trapezius, and gastrocnemius muscles were evaluated. A multi-purpose, portable bio-amplifier (Polymate AP1000) was used for measurement. As a result, the activities of not only the muscles directly involved in mammography positioning but also those indirectly involved were high as compared with the normal state.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

本研究では,マンモグラムのノイズ低減を目的として,ダウンサンプリングを行わない離散定常ウェーブレット変換を繰り返し,隣接する分解レベル間の各方向における階層的相関関係を利用した手法を提案する.まずは,提案手法の有効性をシミュレーションによって検証する.評価指標には情報理論における相互情報量を用いる.次に臨床マンモ画像へ適用し,視覚評価を行う.これらの実験結果から,本提案法は,高周波信号の劣化を抑制しながらノイズ低減を可能にする手法であることが示唆される.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Radiological Technology  

This study focused on measuring examinees' muscle activities during mammography positioning using surface electromyography. Muscle activities were measured in three women (40–50s) in two-view mammography (MLO: mediolateral oblique, CC: craniocaudal). The muscles measured were the sternocleidomastoid, biceps, trapezius, and gastrocnemius, selected based on the visual analogue scale reported by Sharp et al. We used a multi-purpose portable bio-amplifier (Polymate AP1000) to assess the muscle activities. The results showed that the trapezius in right MLO and sternocleidomastoid in right CC were active in all three subjects. This suggests that the muscles directly related to mammography positioning are highly active. In addition, the gastrocnemius was active throughout the mammography. The biceps and gastrocnemius were also active in at least one of the three women. We believe that quantitative assessment of muscle activities during mammography positioning will contribute to the improvement of pain-reduction programs in mammography.

DOI： 10.6009/jjrt.67.679

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00371775378?from=CiNii

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

In this paper, we investigate the effect of the use of wavelet transform for image processing on radiation dose reduction in computed radiography(CR), by measuring various physical characteristics of the wavelet-transformed images. Moreover, we propose a wavelet-based method for offering a possibility to reduce radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates the advantages of two previously proposed techniques, <i>i.e.</i>, sigmoid-type transfer curve for wavelet coefficient weighting adjustment technique, as well as a wavelet soft-thresholding technique. The former can improve contrast and spatial resolution of CR images, the latter is able to decrease image noise. In the investigation of physical characteristics, we measured and compared the modulation transfer function, noise power spectrum, and contrast-to-noise ratio of CR images obtained by the proposed method and other different methods. Furthermore, visual evaluation was performed using Scheffe's pair comparison method. Experimental results showed that the proposed method could improve overall image quality as compared to other methods. Our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved in hip joint radiography by using the proposed method.

DOI： 10.11318/mii.28.51

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本医用画像工学会  

本論文では，単純CT画像における急性期脳梗塞の脳実質低吸収域の描出を目的としたZスコアマッピング法を紹介する．本手法は，ボクセル統計解析に基づき，入力画像の脳形態の標準化を行い，正常脳データベースを用いてボクセルごとにZスコア値を求め，低吸収域を視覚化する．急性期脳梗塞の患者21人に本手法を適用し，Zスコアを入力値として低吸収領域と正常領域のROC曲線を求めた結果，AUC値は0.834となり，本手法が低吸収域を視覚化できることが示された．さらに，神経放射線診断医による観察者実験を行った結果，画像診断時にZスコアマップを参考にすることによって低吸収域検出に関するAUC値が0.883から0.925に向上した．したがって，単純CT画像における急性期脳梗塞の低吸収領域の検出に関して，本手法が放射線科医の読影診断能力の向上に寄与できることが明確に示された．

DOI： 10.11409/mit.29.17

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Objective: Information about image quality of medical images is important for imaging system assessment in order to promote the development and manufacturing of state-of-the-art imaging systems. In this paper, we present a method for evaluating physical performance of digital medical imaging systems using mutual information which is a concept from information theory. To validate the proposed method, computer simulations were performed, followed by measuring and comparing the performance of two digital imaging systems. The results demonstrate the usefulness of the proposed method for evaluating physical quality of medical imaging systems. © 2011 IEEE.

DOI： 10.1109/BMEI.2011.6098601

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

In this paper, we investigate the effect of the use of wavelet transform for image processing on radiation dose reduction in computed radiography (CR), by measuring various physical characteristics of the wavelet-transformed images. Moreover, we propose a wavelet-based method for offering a possibility to reduce radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates the advantages of a previously proposed technique, i.e., sigmoid-type transfer curve for wavelet coefficient weighting adjustment technique, as well as a wavelet soft-thresholding technique. The former can improve contrast and spatial resolution of CR images, the latter is able to improve the performance of image noise. In the investigation of physical characteristics, modulation transfer function, noise power spectrum, and contrast-to-noise ratio of CR images processed by the proposed method and other different methods were measured and compared. Furthermore, visual evaluation was performed using Scheffe's pair comparison method. Experimental results showed that the proposed method could improve overall image quality as compared to other methods. Our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved in hip joint radiography by using the proposed method.

DOI： 10.1117/12.877740

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

In this paper, we investigate the effect of the use of wavelet transform for image processing on radiation dose reduction in computed radiography (CR), by measuring various physical characteristics of the wavelet-transformed images. Moreover, we propose a wavelet-based method for offering a possibility to reduce radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates the advantages of a previously proposed technique, i.e., sigmoid-type transfer curve for wavelet coefficient weighting adjustment technique, as well as a wavelet soft-thresholding technique. The former can improve contrast and spatial resolution of CR images, the latter is able to improve the performance of image noise. In the investigation of physical characteristics, modulation transfer function, noise power spectrum, and contrast-to-noise ratio of CR images processed by the proposed method and other different methods were measured and compared. Furthermore, visual evaluation was performed using Scheffe's pair comparison method. Experimental results showed that the proposed method could improve overall image quality as compared to other methods. Our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved in hip joint radiography by using the proposed method. © 2011 SPIE.

DOI： 10.1117/12.877740

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY  

Purpose: The objective was to develop and investigate an automated scoring scheme of the American College of Radiology (ACR) mammographic accreditation phantom (RMI 156, Middleton, WI) images.
Methods: The developed method consisted of background subtraction, determination of region of interest, classification of fiber and mass objects by Mahalanobis distance, detection of specks by template matching, and rule-based scoring. Fifty-one phantom images were collected from 51 facilities for this study (one facility provided one image). A medical physicist and two radiologic technologists also scored the images. The human and computerized scores were compared.
Results: In terms of meeting the ACR's criteria, the accuracies of the developed method for computerized evaluation of fiber, mass, and speck were 90%, 80%, and 98%, respectively. Contingency table analysis revealed significant association between observer and computer scores for microcalcifications (p &lt; 5%) but not for masses and fibers.
Conclusions: The developed method may achieve a stable assessment of visibility for test objects in mammographic accreditation phantom image in whether the phantom image meets the ACR's criteria in the evaluation test, although there is room left for improvement in the approach for fiber and mass objects. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3516238]

DOI： 10.1118/1.3516238

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本医用画像工学会  

本稿では，相互情報量（mutual information: MI）による画質評価法を，ノイズ低減策としてwaveletしきい値処理を施したPlanar画像に応用し，最適な画質改善をもたらすwavelet基底関数の選択手法を提案する．MI値は画質改善効果が大きいほど高くなる．最初に既存のwavelet基底関数を8種類，候補にあげる．次に原画像に対しuniversalしきい値法を用いてwavelet縮退によるノイズ低減を施す．最後に逆wavelet変換後画像のMIを計算する．実験に用いる画像は，コンピュータ上で作成する2次元grid pattern像とインクジェットプリンタにより作成する面線源ファントム像である．両種類の画像実験の結果は同じ傾向であり，基底関数にdmey waveletを用いた際のMI値がもっとも高い．また，実験結果による提案手法の妥当性を検証するために，画像の標準偏差率とエッジ傾斜比を求め，これらの指標間の比較を行う．これらの結果から，MIによるwavelet基底関数の選択が有効な手法であること，そして低コントラストのplanar画像に最適な基底関数はdmeyであることが示された．

DOI： 10.11409/mit.28.371

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1097/RCT.0b013e3181e66473

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記述言語：日本語   出版者・発行元：日本医用画像工学会  

核医学画像のノイズを低減するためには、収集カウントを増加させる方法や画像データにフィルタリングを施す方法などがある。本研究では、後者に属するwavelet変換によるノイズ低減の手法に着目する。最初に既存のwavelet基底関数を8種類、候補として選択する。次に原画像に対しuniversalしきい値法を用いてwavelet縮退によるノイズ低減を施す。最後にwavelet逆変換後の画像の関心領域における相互情報量(mutual information:MI)を計算する。そしてMIを画質の単一評価指標として用い、8種類のwavelet基底関数で得た画像間の比較評価を行う。さらに、MI値による評価結果の妥当性を検証するために、画像の標準偏差率と画像のエッジ傾斜比を求め、これらの指標間の比較も行う。実験に用いる画像は、コンピュータ上で作成する2次元grid pattern像とインクジェットプリンタにより作成する面線源ファントム像である。これらの実験結果から、MIにより適切なwavelet基底関数の選択ができることを示す。(著者抄録)

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）  

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

医用X線画像では,照射線量の低減に相反する現象として量子ノイズの問題が常に発生する.ノイズの増加を伴わない撮影線量低減の可能性を実現するために様々な画像処理法が提案されている.これらの提案手法は,主に量子モトルの増加に対しノイズの除去を目的としている.本研究の目的は,CR画像にノイズを縮退させるため,4種類のウェーブレット変換を適用させ,処理後画像の基礎的な物理特性を明らかにし,被ばく線量低減効果を検討することである.基礎物理特性としてMTF,NPS,CNR,および人体ファントムのPSNR計測を行う.また,Scheffeの一対比較法による視覚評価も行う.基礎物理特性から,soft-thresholdingを利用した3種類の基底関数による手法は,大幅なノイズ削減ができる.また,シグモイド関数型係数変換法は解像特性の向上が顕著である.視覚評価の結果,シグモイド関数型の利用により,股関節撮影領域に対し,約4割程度の線量低減効果を認めた.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE INC  

Rationale and Objectives: The purpose of this study was to develop a z-score mapping method on the basis of a voxel-by-voxel analysis to visualize hypoattenuation areas of hyperacute stroke on unenhanced computed tomographic (CT) images.
Materials and Methods: The algorithm of the developed method consisted of five main steps: anatomic standardization, the construction of a normal reference database, calculation of the z scores, the elimination of false-positive areas, and the extraction of hypoattenuation areas. The obtained z-score map was then superimposed on the original CT images for identifying hypoattenuation areas of hyperacute stroke on the unenhanced CT images. The method was applied to 21 patients with infarctions of the middle cerebral artery territory &lt;3 hours after symptom onset. The performance of the method was evaluated using receiver-operating characteristic analysis.
Results: Hypoattenuation regions could be significantly distinguished from normal regions by z-score values (P&lt;.0001). The area under the receiver-operating characteristic curve for distinction between 68 hypoattenuation regions and 142 normal regions was 0.834.
Conclusions: The developed method has the potential to accurately indicate high-signal intensity areas corresponding to hypoattenuation areas on CT images in the hyperacute stage of stroke.

DOI： 10.1016/j.acra.2009.07.011

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IOP PUBLISHING LTD  

In this paper, we investigated the effect of the use of wavelet transform on dose reduction in computed radiography (CR). The physical properties of the processed CR images were measured using the modulation transfer function (MTF), noise power spectrum (NPS), contrast-to-noise ratio, and peak signal-to-noise ratio. Furthermore, visual evaluation was performed by Scheffe's pair comparison method. Experimental results showed that sigmoid-type transfer curves for wavelet coefficient weighting adjustment could improve the MTF, and three soft-threshold methods could improve the NPS at all spatial frequency ranges. Moreover, our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved with the sigmoid-type transfer curve in hip joint radiography.

DOI： 10.1088/1742-6596/238/1/012055

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記述言語：日本語   出版者・発行元：医用画像情報学会  

In this paper, a novel application of computer-aided diagnosis (CAD) system, namely portable CAD, was proposed. As a preliminary study, we investigated differences of feature values of nodules calculated by a CAD algorithm, between original chest radiograph and camera image taken by a digital camera. Sixty cases of chest radiographs were used in the study. These radiographs were initially displayed on the monitor, and then taken by the digital camera. Then, the CAD scheme was applied to the obtained camera images. In the CAD scheme, detection of nodule candidates was performed by using matched and ring filters. Two features, area and circularity, were calculated from nodule candidate regions in radiographs and camera images, and were compared respectively. In conclusion, a close correlation between the features calculated from radiographs and camera images was verified.

DOI： 10.11318/mii.27.29

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Radiological Technology  

Joint photographic experts group(JPEG)and JPEG2000 are widely used as image compression algorithms in medical image database systems. Compressed images have been mainly evaluated by visual assessment on acceptable compression levels in clinical studies. However, to the best of our knowledge, little work has been done to clarify image properties based on physical analysis. In this work, investigations were made to clarify image properties based on physical analysis and to discuss the major causes of degradation related to compression ratios. The physical properties of JPEG2000-compressed and JPEG-compressed images in computed radiography(CR)were compared by measuring the characteristic curve, modulation transfer function(MTF), noise power spectrum(NPS), peak signal-to-noise ratio(PSNR), contrast-to-noise ratio(CNR), and noise equivalent quanta(NEQ). In the MTF measurement, the MTFs of JPEG at high compression ratio showed pronounced degradation at all frequencies. The NPS values of JPEG2000 tend to decrease considerably compared to that of the JPEG at all frequencies with the increase of compression ratio. Furthermore, JPEG2000 images showed higher PSNR, CNR, and NEQ values than JPEG images in the same compression ratio. In these signal-to-noise ratio measurements, good reproducibility of JPEG2000 images was achieved. Overall, JPEG2000 compressed images were far superior to JPEG compressed images. In the physical properties measured, these physical analyses are useful to comprehend physical properties for each irreversible compressed image related to compression ratios in CR.

DOI： 10.6009/jjrt.65.1618

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00346507171?from=CiNii

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.6009/jjrt.65.1313

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：I S & T - SOC IMAGING SCIENCE TECHNOLOGY  

We describe an information-theoretic method for quantifying overall image quality in terms of mutual information (MI). MI is used to express the amount of information that an output image contains about an input object. The more the MI value provides, the better the image quality is. Therefore, the overall quality of an image can be quantitatively evaluated by measuring MI. We demonstrated by way of image simulation that MI increases with increasing contrast and decreases with the increase of noise and blur. We investigated the utility of this method by applying it to evaluate the performance of four imaging plate detectors. We also compared evaluation results in terms of MI against those in terms of the detective quantum efficiency conventionally used for characterizing the efficiency performance of imaging systems. Our results demonstrate that the proposed method is simple to implement and has potential usefulness for evaluation of overall image quality. (C) 2009 SPIE and IS&T. [DOI: 10.1117/1.3206967]

DOI： 10.1117/1.3206967

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：新潟大学  

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その他リンク： http://search.jamas.or.jp/link/ui/2009151083

記述言語：日本語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper presents a computerized scheme to assist MRI operators in accurate and rapid determination of sagittal sections for MRI exam of cervical spinal cord. The algorithm of the proposed scheme consisted of 6 steps: (1) extraction of a cervical vertebra containing spinal cord from an axial localizer image
(2) extraction of spinal cord with sagittal image from the extracted vertebra
(3) selection of a series of coronal localizer images corresponding to various, involved portions of the extracted spinal cord with sagittal image
(4) generation of a composite coronal-plane image from the obtained coronal images
(5) extraction of spinal cord from the obtained composite image
(6) determination of oblique sagittal sections from the detected location and gradient of the extracted spinal cord. Cervical spine images obtained from 25 healthy volunteers were used for the study. A perceptual evaluation was performed by five experienced MRI operators. Good agreement between the automated and manual determinations was achieved. By use of the proposed scheme, average execution time was reduced from 39 seconds/case to 1 second/case. The results demonstrate that the proposed scheme can assist MRI operators in performing cervical spinal cord MRI exam accurately and rapidly. © 2009 Copyright SPIE - The International Society for Optical Engineering.

DOI： 10.1117/12.811082

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IMEKO  

Information on physical image quality of medical images is important for imaging system assessment in order to promote and stimulate the development of state-of-the-art imaging systems. In this paper, we present a method for measuring physical performance of medical imaging systems. In this method, mutual information (MI) which is a concept from information theory was used to measure combined properties of image noise and resolution of an imaging system. In our study, the MI was used as a measure to express the amount of information that an output image contains about an input object. The more the MI value provides, the better the image quality is. To validate the proposed method, computer simulations were first performed to investigate the effects of noise and resolution degradation on the MI. Then experiments were conducted to measure the physical performance of an imaging plate which was used as an image detector. Our simulation and experimental results confirmed that the combined effect of deteriorated blur and noise on the images can be measured and analyzed using the MI metric. The results demonstrate the potential usefulness of the proposed method for measuring physical quality of medical imaging systems.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

Manual determination of an oblique sagittal imaging plane with high accuracy in lumbar spine magnetic resonance imaging(MRI)needs time, experience and expertise. In this paper we present a simple and fast setting system for assisting MRI operators in their routine work to automatically and accurately determine oblique sagittal imaging plane in lumbar spine MRI. The algorithm of the presented method consists of three major steps:(1)extraction of torso region from coronal localizer image by use of histogram analysis,(2)extraction of lumbar vertebra and spinal canal regions by use of minimization and maximization filters as well as density accumulation analysis, and(3)determination of the desired position and angle of sagittal imaging plane using Hough transform. In order to evaluate the performance of our proposed method, positions and angles of the sagittal imaging planes determined by the presented method were evaluated by five radiological technologists. Thirty healthy volunteers participated in this study. All the 5 observers confirmed that the automatically determined imaging planes of all the 30 cases were acceptable for subsequent imaging procedures.

DOI： 10.11318/mii.25.54

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

Pre-processing is important for digital medical images because it can contribute to the improvement of diagnostic accuracy with medical images and computer-aided diagnosis. In this paper, a novel sigmoid-type transfer curve for wavelet coefficient weighting adjustment was proposed to improve contrast of medical images. The proposed method was applied to chest radiographs, mammograms and chest CT images, and then its performance was quantitatively evaluated with contrast improvement ratio. As a result, contrasts of all applied images were obviously improved. Compared with the conventional exponential-type transfer curve, the proposed sigmoid-type transfer curve was more effective with a statistical significance(<i>p</i><0.05).

DOI： 10.11318/mii.25.48

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer New York  

This paper presents a simple and straightforward method for synthetically evaluating digital radiographic images by a single parameter in terms of transmitted information (TI). The features of our proposed method are: (1) simplicity of computation, (2) simplicity of experimentation, and (3) combined assessment of image noise and resolution (blur). Two acrylic step wedges with 0-1-2-3-4-5 mm and 0-2-4-6-8-10 mm in thickness were used as phantoms for experiments. In the present study, three experiments were conducted. First, in order to investigate the relation between the value of TI and image noise, various radiation doses by changing exposure time were employed. Second, we examined the relation between the value of TI and image blurring by shifting the phantoms away from the center of the x-ray beam area toward the cathode end when imaging was performed. Third, we analyzed the combined effect of deteriorated blur and noise on the images by employing three smoothing filters. Experimental results show that the amount of TI is closely related to both image noise and image blurring. The results demonstrate the usefulness of our method for evaluation of physical image quality in medical imaging.

DOI： 10.1007/s10278-007-9044-5

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：新潟大学  

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その他リンク： http://search.jamas.or.jp/link/ui/2008264517

記述言語：英語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：新潟大学  

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その他リンク： http://search.jamas.or.jp/link/ui/2008264516

掲載種別：研究論文（学術雑誌）  

DOI： 10.6009/jjrt.64.881

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC MEDICINE PRESS LTD  

Background: Much attention has been directed toward identifying early signs of cerebral ischemia on computed tomography (CT) images. Hypoattenuation of ischemic brain parenchyma has been found to be the most frequent early sign.
Purpose: To evaluate the effect of a previously proposed adaptive smoothing filter for improving detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images.
Material and Methods: Twenty-six patients with parenchymal hypoattenuation and 49 control subjects without hypoattenuation were retrospectively selected in this study. The adaptive partial median filter (APMF) designed for improving detectability of hypoattenuation areas on unenhanced CT images was applied. Seven radiologists, including four certified radiologists and three radiology residents, indicated their confidence level regarding the presence (or absence) of hypoattenuation on CT images, first without and then with the APMF processed images. Their performances without and with the APMF processed images were evaluated by receiver operating characteristic (ROC) analysis.
Results: The mean areas under the ROC curves (AUC) for all observers increased from 0.875 to 0.929 (P=0.002) when the radiologists observed with the APMF processed images. The mean sensitivity in the detection of hypoattenuation significantly improved, from 69% (126 of 182 observations) to 89% (151 of 182 observations), when employing the APMF (P=0.012). The specificity, however, was unaffected by the APMF (P=0.41).
Conclusion: The APMF has the potential to improve the detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images.

DOI： 10.1080/02841850802126570

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

This paper presents an information-entropy based metric for combined evaluation of resolution and noise properties of radiological images. The metric is expressed by the amount of transmitted information (TI). It is a measure of how much information that one image contains about an object or-an input. Merits of the proposed method are its simplicity of computation and the experimented setup. A computer-simulated step wedge was used for simulation study on the relationship of TI and the degree of blur as well as the noise. Three acrylic step wedges were also manufactured and used as test sample objects for experiments. Two imaging plates for computed radiography were employed as information detectors to record X-ray intensifies. We investigated the effects of noise and resolution degradation on the amount of TI by varying exposure levels. Simulation and experimental results show that the TI value varies when the noise level or the degree of blur is changed. To validate the reasoning and usefulness of the proposed metric, we also calculated and compared the modulation transfer functions and noise power spectra for the employed imaging plates. Results show that the TI has close correlation with both image noise and image blurring, and it may offer the potential to become a simple and generally applicable measure for quality evaluation of medical images.

DOI： 10.1117/12.768324

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper presents an information-entropy based metric for combined evaluation of resolution and noise properties of radiological images. The metric is expressed by the amount of transmitted information (TI). It is a measure of how much information that one image contains about an object or an input. Merits of the proposed method are its simplicity of computation and the experimented setup. A computer-simulated step wedge was used for simulation study on the relationship of TI and the degree of blur as well as the noise. Three acrylic step wedges were also manufactured and used as test sample objects for experiments. Two imaging plates for computed radiography were employed as information detectors to record X-ray intensities. We investigated the effects of noise and resolution degradation on the amount of TI by varying exposure levels. Simulation and experimental results show that the TI value varies when the noise level or the degree of blur is changed. To validate the reasoning and usefulness of the proposed metric, we also calculated and compared the modulation transfer functions and noise power spectra for the employed imaging plates. Results show that the TI has close correlation with both image noise and image blurring, and it may offer the potential to become a simple and generally applicable measure for quality evaluation of medical images.

DOI： 10.1117/12.768324

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER HEIDELBERG  

Purpose: Detection of early CT signs of infarct in non-enhanced CT image is mandatory in patients with acute ischemic stroke. Loss of the gray-white matter interface at the lentiform nucleus or the insular ribbon has been an important early CT sign of acute cerebral infarction, which affects decisions on thrombolytic therapy. However, its detection is difficult, since the principal early CT sign is subtle hypoattenuation. An image processing method to reduce local noise with edges preserved was developed to improve infarct detection.
Rationale: An adaptive partial median filter (APMF) was selected for this application, since the APMF can markedly improve the visibility of the normal gray-white matter interface. APMF should enhance the conspicuity of gray-white matter interface changes due to hypoattenuation that accompanies cerebral infarction.
Method: In a criterion referenced performance study using simulated CT images with gray-white matter interfaces, a total of 14 conventional smoothing filters were also used for comparison to validate the usefulness of the proposed APMF. The APMF indicated the highest performance among the compared methods. Then, observer performance study by receiver operator characteristic (ROC) analysis was performed with 4 radiologist observers using a database with 18 abnormal and 33 normal head CT images.
Results: The average A(z) values of ROC curves for all radiologists increased from 0.876 without the APMF images to 0.926 with the APMF images, and this difference was statistically significant (P = 0.04).
Conclusions: The results from the two observer performance studies demonstrated that APMF has significant potential to improve the diagnosis of acute cerebral infarction using non-enhanced CT images.

DOI： 10.1007/s11548-007-0123-3

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人日本放射線技術学会  

This paper describes an approach to automatically detect the parenchymal hypoattenuation of hyperacute stroke in nonenhanced computed tomography (CT) images. This technique is based on a comparison between the CT values histograms of right and left brains. A subtraction curve that was regarded as an output value was calculated by subtracting the right-hemispherical histogram from the left-hemispherical histogram obtained from one of the region-of-interest (ROI) sets on an image. The output value was used to assess whether hypoattenuation exists on CT images with a threshold value. If judged abnormal, a rectangular region including a whole or partial hypoattenuation area was detected from the ROI. Twenty-six cases with hypoattenuation and 30 cases without hypoattenuation were included in this study. As a result of our experiments, the sensitivity of this method in detecting hypoattenuation was found to be 92%, with approximately 0.16 false-positive per image. Our preliminary experimental results indicated that the proposed technique can be used for the automated detection of parenchymal hypoattenuation of hyperacute stroke on nonenhanced CT images.

DOI： 10.6009/jjrt.63.835

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Purpose. The aim of this study was to evaluate the performance of a novel noise reduction filter for improving the visibility of early computed tomography (CT) signs of hyperacute stroke on nonenhanced CT images. Material and methods. Fourteen patients with a middle cerebral artery occlusion within 4.5 h after onset were evaluated. The signal-to-noise ratio (SNR) of the processed images with the noise reduction filter and that of original images were measured. Two neuroradiologists visually rated all the processed and original images on the visibility of normal and abnormal gray-white matter interfaces. Results. The SNR value of the processed images was approximately eight times as high as that of the original images, and a 87% reduction of noise was achieved using this technique. For the visual assessment, the results showed that the visibility of normal gray-white matter interface and that of the loss of the gray-white matter interface were significantly improved using the proposed method (P &lt
0.05). Conclusion. The noise reduction filter proposed in the present study has the potential to improve the visibility of early CT signs of hyperacute stroke on nonenhanced CT images. © 2007 Japan Radiological Society.

DOI： 10.1007/s11604-007-0129-3

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.6009/jjrt.63.341

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人電子情報通信学会  

Computed tomography (CT)は,急性期脳梗塞の画像診断のための重要な検査法の一つである.本研究では,頭部単純CT画像において急性期脳梗塞の描出能改善を目的した適応型部分メディアンフィルタ(APMF)を提案する.APMFは,選択的に信号成分を保存しながら,ノイズ成分のみを低減させることができる.シミュレーション実験によって,急性期脳梗塞の描出能改善に適したAPMFのパラメータを設定し,臨床画像に適用した.その結果,頭部CT画像上での急性期脳梗塞の描出能に顕著な改善が認められた.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

関心領域内のエッジを選択的に保ちながらノイズ低減を行う適応型部分平均フィルタ（APAF）を提案する．X線CTとファントム画像を用いてシミュレーション実験を行った結果，APAFがエッジの保存率の観点から，単純な移動平均フィルタやメジアンフィルタより優れていることが確認された．

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その他リンク： http://hdl.handle.net/10191/8168

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技術学会  

DOI： 10.6009/jjrt.62.447

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その他リンク： http://hdl.handle.net/10191/4863

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人電子情報通信学会  

肺がんの罹患率は増加傾向にあり, 最近ではCT画像を用いた検診も行われるようになった.しかし, CT画像による診断は多量に発生する画像を読影するために読影医の負担は大きいのが現状である.そこでわれわれは, 肺がんの画像診断を支援するコンピュータ支援診断システム(CAD)の開発を行ってきた.本報告では, 胸壁に接した陰影の検出のために, 胸壁に沿ったテンプレートマッチング法(LWTM)と, 高次局所自己相関特徴を用いたパターン認識手法を用いた検出システムを提案し, 有効性を検討するために胸部X線CT画像への応用を行った.結節状陰影が含まれる35症例に適用した結果, 検出率が86.3%, 偽陽性候補数が症例あたり10.9個という結果を得た.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

Detection of early infarct signs on non-enhanced CT is mandatory in patients with acute ischemic stroke. We present a method for improving the detectability of early infarct signs of acute ischemic stroke. This approach is considered as the first step for computer-aided diagnosis in acute ischemic stroke. Obscuration of the gray-white matter interface at the lentiform nucleus or the insular ribbon has been an important early infarct sign, which affects decisions on thrombolytic therapy. However, its detection is difficult, since the early infarct sign is subtle hypoattenuation. In order to improve the detectability of the early infarct sign, an image processing being able to reduce local noise with edges preserved is desirable. To cope with this issue, we devised an adaptive partial smoothing filter (APSF). Because the APSF can markedly improve the visibility of the normal gray-white matter interface, the detection of conspicuity of obscuration of gray-white matter interface due to hypoattenuation could be increased. The APSF is a specifically designed filter used to perform local smoothing using a variable filter size determined by the distribution of pixel values of edges in the region of interest. By adjusting four parameters of the APSF, an optimal condition for image enhancement can be obtained. In order to determine a major one of the parameters, preliminary simulation was performed by using composite images simulated the gray-white matter. The APSF based on preliminary simulation was applied to several clinical CT scans in hyperacute stroke patients. The results showed that the detectability of early infarct signs is much improved.

DOI： 10.1117/12.654242

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

In this paper we describe a method for assisting radiological technologists in their routine work to automatically determine the imaging plane in lumbar MRI. The method is first to recognize the spinal cord and the intervertebral disk (ID) from the lumbar vertebra 3-plane localizer image, and then the imaging plane is automatically determined according to the recognition results. To determine the imaging plane, the spinal cord and the ID are automatically recognized from the lumbar vertebra 3-plane localizer image with a series of image processing techniques. The proposed method consists of three major steps. First, after removing the air and fat regions from the 3-plane localizer image by use of histogram analysis, the rachis region is specified with Sobel edge detection filter. Second, the spinal cord and the ID were respectively extracted from the specified rachis region making use of global thresholding and the line detection filter. Finally, the imaging plane is determined by finding the straight line between the spinal cord and the ID with the Hough transform. Image data of 10 healthy volunteers were used for investigation. To validate the usefulness of our proposed method, manual determination of the imaging plane was also conducted by five experienced radiological technologists. Our experimental results showed that the concordance rate between the manual setting and automatic determination reached to 90%. Moreover, a remarkable reduction in execution time for imaging-plane determination was also achieved.

DOI： 10.1117/12.652908

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Detection of early infarct signs on non-enhanced CT is mandatory in patients with acute ischemic stroke. We present a method for improving the detectability of early infarct signs of acute ischemic stroke. This approach is considered as the first step for computer-aided diagnosis in acute ischemic stroke. Obscuration of the gray-white matter interface at the lentiform nucleus or the insular ribbon has been an important early infarct sign, which affects decisions on thrombolytic therapy. However, its detection is difficult, since the early infarct sign is subtle hypoattenuation. In order to improve the detectability of the early infarct sign, an image processing being able to reduce local noise with edges preserved is desirable. To cope with this issue, we devised an adaptive partial smoothing filter (APSF). Because the APSF can markedly improve the visibility of the normal gray-white matter interface, the detection of conspicuity of obscuration of gray-white matter interface due to hypoattenuation could be increased. The APSF is a specifically designed filter used to perform local smoothing using a variable filter size determined by the distribution of pixel values of edges in the region of interest. By adjusting four parameters of the APSF, an optimal condition for image enhancement can be obtained. In order to determine a major one of the parameters, preliminary simulation was performed by using composite images simulated the gray-white matter. The APSF based on preliminary simulation was applied to several clinical CT scans in hyperacute stroke patients. The results showed that the detectability of early infarct signs is much improved.

DOI： 10.1117/12.654242

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Verlag  

DOI： 10.1007/s11548-006-0031-y

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

In this paper we describe a method for assisting radiological technologists in their routine work to automatically determine the imaging plane in lumbar MRI. The method is first to recognize the spinal cord and the intervertebral disk (ID) from the lumbar vertebra 3-plane localizer image, and then the imaging plane is automatically determined according to the recognition results. To determine the imaging plane, the spinal cord and the ID are automatically recognized from the lumbar vertebra 3-plane localizer image with a series of image processing techniques. The proposed method consists of three major steps. First, after removing the air and fat regions from the 3-plane localizer image by use of histogram analysis, the rachis region is specified with Sobel edge detection filter. Second, the spinal cord and the ID were respectively extracted from the specified rachis region making use of global thresholding and the line detection filter. Finally, the imaging plane is determined by finding the straight line between the spinal cord and the ID with the Hough transform. Image data of 10 healthy volunteers were used for investigation. To validate the usefulness of our proposed method, manual determination of the imaging plane was also conducted by five experienced radiological technologists. Our experimental results showed that the concordance rate between the manual setting and automatic determination reached to 90%. Moreover, a remarkable reduction in execution time for imaging-plane determination was also achieved.

DOI： 10.1117/12.652908

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技術学会  

Detection of early infarct signs on nonenhanced CT is mandatory in patients with acute ischemic stroke. Loss of the gray-white matter interface at the lentiform nucleus or the insular ribbon has been an important early infact sign, which affects decisions on thrombolytic therapy. However, its detection is difficult, since early infarct sign is of subtle hypoattenuation. To improve the detectability of early infarct sign, image processing that could reduce local noise while preserving edges is desirable. To examine this issue, we devised an adaptive partial smoothing filter(APSF). Since the APSF markedly improves visibility of the normal gray-white matter interface, loss of the gray-white matter interface due to hypoattenuation could be more easily detected. The APSF was applied to clinical CT images in hyperacute stroke patients. Our preliminary results showed that the visibility and detectability of early infarct signs was much improved. To validate the usefulness of the proposed method, two commonly used smoothing filters were also employed for comparison. The results demonstrated the superiority of the APSF. Our proposed APSF can improve the visibility of the gray-white matter interface, thereby enhancing the detectability of early infarct signs.

DOI： 10.6009/jjrt.KJ00004010674

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その他リンク： http://hdl.handle.net/10191/4862

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11409/mit.23.239

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技術学会  

This paper presents an improved adaptive-neighborhood-contrast-enhancemen（t ANCE）method for the improvement of medical image quality. The ANCE method consists of computing the local contrast around each pixel using a variable neighborhood whose size depends on the statistical properties around the given pixel. The obtained contrast image is then transformed into a new contrast image using a contrast enhancement function. Finally, a contrast-enhanced image is obtained by applying inverse contrast transform to the previous step. This technique provides the advantages of enhancing or preserving image contrast while suppressing noise. However, it does have a drawback. The performance of the ANCE method largely depends on how to determine the parameters used in the processing steps. The present study proposes a novel method for optimal and automatic determination of several parameters using entropy. To quantitatively compare the performance of the proposed method with that of the ANCE method, computer-simulated images are generated. The output-to-input SNR level and the mean squared error are used as comparison criteria. Results demonstrated the superiority of the proposed method. Moreover, we have applied our new algorithm to echocardiograms and mammograms. Our results showed that the proposed method has the potential to become useful for improving the image quality of medical images.

DOI： 10.6009/jjrt.KJ00003326665

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その他リンク： http://hdl.handle.net/10191/4861

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

We present an adaptive smoothing filter aiming to improve the visibility and detectability of the obscuration of the lentiform, nucleus, which is one of the early signs of acute cerebral artery infraction, in CT brain images. The proposed method is able to enhance image data by removing noise without significantly blurring the structures in the images. This method is tested both on computer-simulated image data and on clinical CT brain images. Moreover, a comparison of the proposed method to two commonly used techniques is made. Preliminary results demonstrate the superiority of the proposed method and its usefulness for detecting the obscuration of the lentiform nucleus, which could not be detected previously without using the proposed method.

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記述言語：日本語   出版者・発行元：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00004028181

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：I S & T - SOC IMAGING SCIENCE TECHNOLOGY  

In this paper we present a genetic-algorithm-based fuzzy-logic approach for computer-aided diagnosis scheme in medical imaging. The scheme is applied to discriminate myocardial heart disease from echocardiographic images and to detect and classify clustered microcalcifications from mammograms. Unlike the conventional types of membership functions such as trapezoid, triangle, S curve, and singleton used in fuzzy reasoning, Gaussian-distributed fuzzy membership functions (GDMFs) are employed in the present study. The GDMFs are initially generated using various texture-based features obtained from reference images. Subsequently the shapes of GDMFs are optimized by a genetic-algorithm learning process. After optimization, the classifier is used for disease discrimination. The results of our experiments are very promising. We achieve an average accuracy of 96% for myocardial heart disease and accuracy of 88.5% at 100% sensitivity level for micro-calcification on mammograms. The results demonstrated that our proposed genetic-algorithm-based fuzzy-logic approach is an effective method for computer-aided diagnosis in disease classification. 2004, SPIE and IST.

DOI： 10.1117/1.1786607

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：(公社)日本医学物理学会  

多列Multi-slice CTの開発に伴い,これまでのline spread function(LSF)やslice sensitivity profile(SSP)を用いた1次元での検討から,2次元や3次元に拡張しての検討が重要になるが,LSFやSSPとpoint spread function(PSF)の関係について詳細に論ずる報告はみあたらない.そこで,LSFおよびSSPとPSFの関係について理論的に考察し,シミュレーションを加えて,それらの関連を明らか場合,その系のPSF'(x,y,z)はLSSFx(X)とLSFy(Y)およびSSP(z)の積で表すことができ,PSF(x,y)はLSFx(X)とLSFy(Y)の積で表すことができた

DOI： 10.11323/jjmp2000.24.3_115

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その他リンク： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2004&ichushi_jid=J03418&link_issn=&doc_id=20041201260002&doc_link_id=10014056519&url=https%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F10014056519&type=CiNii&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00003_1.gif

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技術学会  

脳血管疾患はわが国の死因のうち悪性新生物,心疾患に続く重篤な疾患である.脳血管疾患は,脳卒中を引き起こす主要因であり,具体的には脳梗塞,脳内出血,くも膜下出血等を示す.脳梗塞は血管の閉塞や狭窄に起因し,血液の流れが妨げられることによって起こる.脳内出血やくも膜下出血は脳動脈瘤や動静脈奇形等の破裂に起因する.近年の診断・治療法の著しい進歩により急性期死亡率は減少してきたが,受療率は高位で推移している.また,たとえ救命されても再発と後遺症のために生活の質が低下することが多いのが現状である.そのため,脳血管疾患の場合には血管病変部の早期発見・診断・治療が特に重要となる. 現在,種々の新しい画像診断法が開発・提唱され脳血管疾患の診断にも応用されている.脳血管疾患の画像診断では,主としてcomputed tomographic angiography(CTA),magnetic resonance angiography(MRA),digital subtraction angiography (DSA)が有用である.そのなかで特に,CTAで得られる画像は,時間分解能や空間分解能の点でMRAより優れており,DSAより侵襲性が低い.脳動脈瘤症例においては.DSAを行わずCTA単独で手術を行う施設もある.また,CTAでは.shaded surface displayやvolume rendering(VR)で構築される三次元画像によって,脳血管や病変部の空間的位置関係が立体的に表示できるようになった.さらに,それらの三次元画像によって,病変部(未破裂性脳動脈瘤など)の微細形態など従来では得られなかった情報が取得できるようになり,3D診断や外科的手術シミュレーションなどに多く利用されつつある.しかしながら,頭部CTAのvolume dataから診断用の三次元脳血管画像(主にVR像)を作成することは,通常,三次元画像解析装置上で医師や診療放射線技師の手作業によって行われている.具体的には,血管が観察できる適当なwindow levelとwindow widthを設定し,その後多角形ツール等を用いて手動で周りの骨を削っていく.これは,頭部CTAでは脳血管とともに必ず骨領域も一緒に写り,さらにCT値も両領域でオーバーラップしていることに起因する.また,三次元画像で脳血管の診断を行うとき,多視点で画像を眺める(VR像を回転させる)ことは診断精度の向上につながる.このとき,頭蓋骨が邪魔になるため,骨領域を削除するのが通常である.しかし,この骨領域を除去する作業は,特に精密に除去する場合,多大な労力を要し,さらに再現性にも乏しいといわれている.そのため,最近はCTA画像から半自動的に骨領域を除去する手法も検討されはじめている.こうした背景を踏まえて,本研究では,頭部CTA画像から自動的に脳血管領域のみを抽出する一手法を提案する.本手法の特徴として,一般的によく用いられる2値化処理,ラベリング処理のほかに,改良したラプラシアン型フィルタを用いること,そして通常の頭部CTAで得られるaxial断面像のほかに,sagittal,coronal断面像を再構成し(Fig.1),それぞれの断面で処理を繰り返すことなどが挙げられる.本稿では,提案手法の詳細とその有効性を検討するために3症例の頭部CTA画像に適用した結果を報告する.

DOI： 10.6009/jjrt.KJ00003174600

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その他リンク： http://search.jamas.or.jp/link/ui/2005025516

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）   出版者・発行元：知的診断支援 総括班  

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

The purpose of this study is to compare four CAD-algorithms under the same condition, and to verify the most effective algorithm for the classification of microcalcifications on mammogram. The four CAD-algorithms are BP-ANN, GA-ANN, FL and GA-FL. BP-ANN is a conventional artificial neural network with back-propagation learning. GA-ANN is an improved ANN based on genetic algorithm to determine the weighting coefficients at ANN. FL is a conventional fuzzy logic algorithm using gaussian-distributed membership functions. GA-FL is an improved FL based on genetic algorithm to optimize the membership functions. Comparison results are indicated by ROC curves. The Az values of the ROC curves for BP-ANN, GA-ANN, FL and GA-FL were 0.86, 0.80, 0.89 and 0.95, respectively. When sensitivity of each algorithm was 100%, specificities of BP-ANN, GA-ANN, FL and GA-FL were 69%, 54%, 31% and 77%, respectively. Therefore, these results show the effectiveness of GA-FL algorithm. GA-FL has a potential to become useful CAD algorithm to classify microcalcifications on mammogram.

DOI： 10.11318/mii.21.122

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掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG BERLIN  

This paper presents an improved adaptive neighborhood contrast enhancement (ANCE) method for improvement of medical image quality. The ANCE method provides the advantages of enhancing or preserving image contrast while suppressing noise. However, it has a drawback. The performance of the ANCE method largely depends on how to determine the parameters used in the processing steps. The present study proposes a novel method for optimal and automatic determination of threshold-value and neighborhood-size parameters using entropy. To quantitatively compare the performance of the proposed method with that of the ANCE method, computer-simulated images are generated. The output-to-input SNR ratio and the mean squared error are used as comparison criteria. Results demonstrate the superiority of the proposed method. Moreover, we have applied our new algorithm to echocardiograms. Our results show that the proposed method has the potential to become useful for improvement of image quality of medical images.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

We previously developed a scheme to automatically detect pulmonary nodules on CT images, as a part of computer-aided diagnosis (CAD) system. The proposed method consisted of two template-matching approaches based on simple models that simulate real nodules. One was a new template-matching technique based on a genetic algorithm (GA) template matching (GATM) for detecting nodules within the lung area. The other one was a conventional template matching along the lung wall [lung wall template matching (LWTM)] for detecting nodules on the lung wall. After the two template matchings, thirteen feature values were calculated and used for eliminating false positives. Twenty clinical cases involving a total of 557 sectional images were applied; 71 nodules out of 98 were correctly detected with the number of false positives at approximately 30.8/case by applying two template matchings (GATM and LWTM) and elimination process of false positives. In this study, five features were newly added, and threshold-values of our previous features were reconsidered for further eliminating false positives. As the result, the number of false positives was decreased to 5.5/case without elimination of true positives.

DOI： 10.1117/12.536162

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

The purpose of this study is to develop a computerized scheme for the discrimination between benign and malignant clustered microcalcifications that would aid radiologists in interpreting mammograms. In our scheme, microcalcifications in regions of interest (ROIs) are detected by using morphological filter. Then, four feature values including the total number, mean area, mean circularity and mean minimum distance of microcalcifications are calculated for classification. Gaussian-distributed membership functions used for fuzzy logic are determined from means and standard deviations of these feature values. Finally, fuzzy logic using the genetic-algorithm for optimization of membership functions is employed to classify clustered microcalcifications in unknown ROI. Our scheme was applied to twenty mammographic images with microcalcifications in the Mammographic Image Analysis Society database, containing thirteen benign and twelve malignant ROIs. Of the images ten each benign and malignant ROIs were used for training in fuzzy logic. The remaining five images were classified as benign or malignant cases by fuzzy logic. All sets of their combinations were employed to obtain the result. As the results, the average accuracy was approximately 88% (sensitivity: 100%, specificity: 77%), and Az value of ROC curve was 0.95.

DOI： 10.1117/12.536274

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記述言語：日本語   出版者・発行元：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00003174512

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：新潟大学医学部保健学科  

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その他リンク： http://search.jamas.or.jp/link/ui/2004194207

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11239/jsmbe2002.41.105

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

An approach to,medical image enhancement is proposed. In this method, non-linear mapping functions are derived for projecting a set of discrete wavelet transform (DWT) coefficients to a new set of DWT coefficients. The mapped coefficients are then inverse wavelet transformed. Applications of the proposed method to the chest x-ray images and mammograms with subtle micro-calcifications are shown. To validate the effectiveness of the proposed method, we compared the results to those obtained by the fast Fourier transform (FFT) and the conventional wavelet-based (CWB) methods. Our preliminary results strongly suggest that the proposed method offers considerably improved enhancement capability over the FFT and CWB methods.

DOI： 10.1109/ICNNSP.2003.1281059

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本放射線技術学会  

The purpose of this study is to develop a technique to detect lacunar infarct regions automatically in brain MR images. Our detection method is based on the definition of lacunar infarcts. After inputted images were binarized, we used feature values such as area, circularities and the center of gravity of candidate regions to extract isolated lacunar infarct regions. We also developed and used a new filter to enhance the signals of lacunar infarcts adjacent to some high intensity regions. 10 cases involving 81 sectional images were applied to our experiment. As a result, the sensitivity was 100％ with approximately 1.77 false-positives per image. Our results are promising on the first stage, although it remains to improve on problems that to eliminate false-positives and automatically establish threshold value.

DOI： 10.6009/jjrt.KJ00001364293

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その他リンク： http://search.jamas.or.jp/link/ui/2002207001

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11239/jsmbe1963.40.86

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SCRIPTA TECHNICA-JOHN WILEY & SONS  

This paper describes a fuzzy-reasoning-based computer-aided diagnosis scheme for automated classification of cardiomyopathy from ultrasonic images. Unlike the conventional types of membership functions such as triangle and trapezoid, Gaussian-distributed membership functions (GDMFs) are employed in the present study. The GDMFs are initially generated using various texture-based features computed from gray-level co-occurrence matrices. Subsequently, the shapes of GDMFs are optimized by a genetic-algorithm learning process. After optimization, the classifier is used to discriminate two sets of echocardiographic images, namely, normal and abnormal cases, which were diagnosed in advance by a highly trained physician. We experimentally evaluate the performance of the proposed method against various methods reported in terms of sensitivity, specificity, and total accuracy. Our results show the promise of the proposed approach in discriminating cardiomyopathy. (C) 2002 Wiley Periodicals, Inc.

DOI： 10.1002/ecjc.10025

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

This paper presents a wavelet-based method for medical image enhancement. In the proposed method, a transfer function is derived for transferring wavelet coefficients at various multiresolution levels with different weighting values. Applications of the rnethod to digital radiographic images of x-ray chest are shown. Moreover, in order to validate the effectiveness of the proposed method, we compare the results obtained using the wavelet analysis method to that using the conventional fast Fourier transform (FFT) method. The results show that the proposed method is superior to the FFT method in terms of image enhancement.

DOI： 10.1109/ICOSP.2002.1181158

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

超音波診断法は，簡便で有用な画像診断法の一つである．この診断法は，心臓疾患の診断にも発揮され，広く用いられてきた．心臓疾患の中で心筋症は比較的よくある病気の一種である．この心筋症をより正確に診断できることは重要である．本論文では，心筋症のコンピュータ支援診断システムの構築を目的とし，ファジィ推論に基づく支援診断の一手法を提案する．提案手法は，従来よく用いられる三角形や台形のようなメンバシップ関数ではなく，ガウス分布形メンバシップ関数を用いることと，メンバシップ関数の形を最適化するためにGAを用いることを特徴としている．提案法の性能を，正確度（正診率），感度（有病正診率）及び特異度（無病正診率）の三つのインデックスで評価した．その結果，本手法が支援診断に有効であることが示唆された．

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その他リンク： http://hdl.handle.net/10191/6555

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11318/mii1984.18.135

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

The purpose of this study is to develop a technique for computer-aided diagnosis (CAD) systems to detect lung nodules in helical X-ray pulmonary computed tomography CT) images. We propose a novel template-matching technique based on a genetic algorithm (GA) template matching (GATM) for detecting nodules existing within the lung area; the GA was used to determine the target position in the observed image efficiently and to select an adequate template image from several reference patterns for quick template matching. In addition, a conventional template matching was employed to detect nodules existing on the lung wall area,lung wall template matching (LWTM), where semicircular models were used as reference patterns; the semicircular models were rotated according to the angle of the target point on the contour of the lung wall. After initial detecting candidates using the two template-matching methods, we extracted a total of 13 feature values and used them to eliminate false-positive findings. Twenty clinical cases involving a total of 557 sectional images were used in this study. 71 nodules out of 98 were correctly detected by our scheme (i,e,, a detection rate of about 72%), with the number of false positives at approximately 1.1/sectional image, Our present results show that our scheme can be regarded as a technique for CAD systems to detect nodules in helical CT pulmonary images.

DOI： 10.1109/42.932744

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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DOI： 10.1118/1.1382823

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

This paper presents a fuzzy-reasoning-based computer-aided diagnosis scheme for automated classification of heart disease from ultrasonic images. Unlike the conventional types of membership functions, Gaussian-distributed membership functions (GDMFs) are employed in the present study. The GDMFs are initially generated using various texture-based features computed from gray-level co-occurrence matrices. Subsequently, the shapes of GDMFs are optimized by genetic-algorithm learning process. After optimization, the classifier is used to discriminate two sets of echocardiographic images, namely, normal and abnormal cases, which were diagnosed in advance by a highly trained physician. We experimentally evaluate the performance of the proposed method against various methods been reported in terms of accuracy, sensitivity, and specificity. Experimental results show that the proposed method has potential utility for computer-aided diagnosis of myocardial heart disease.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：FUDAN UNIV PRESS  

In recent years, considerable and serious efforts have been made toward the development of computer aided diagnosis (CAD) systems in diagnostic radiology. The CAD in radiology is a diagnosis made by a clinician (radiologist) who uses the output from a computerized analysis of medical images as a second opinion. In this paper we describe two CAD systems using artificial neural networks (ANNs). The first system is an application to the segmentation of liver region in computed tomographic images for 3D visualization. The second system is an application to classification of cardiac disease. Results show that the presented systems using the ANNs give considerably satisfactory detection and classification performance.

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記述言語：日本語   出版者・発行元：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00003111315

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11318/mii1984.17.118

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

The purpose of this work is to present some technical approaches of our computer-aided detection (CAD) system for chest radiograms and helical CT scans, and also evaluate that by using three databases. The CAD includes some methods to detect lesions and to eliminate false-positive findings. The detection methods consist of template matching and artificial neural network approaches. A genetic algorithm (GA) was employed in template matching to select a matched image from various reference patterns. Artificial neural networks (ANN) were also applied to eliminate the false-positive candidates. The sensitivity and the number of false-positives were 73% and 11 FP per image on chest radiogram CAD and 77% with 2.6 FP per image on helical CT scan CAD. These preliminary results imply that the GA and ANN-based detection methods may be effective in indicating lesions on chest radiograms and helical CT scans. © 1999 IEEE.

DOI： 10.1109/ICIAP.1999.797688

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

The purpose of this work is to present some technical approaches of our computer-aided diagnosis (CAD) system for chest radiograms and helical CT scans, and also evaluate that by using three databases. The CAD includes some methods to detect lesions and to eliminate false-positive findings. The detective methods consist of template matching and artificial neural network approaches. Genetic Algorithm (GA) was employed in template matching to select a matched image from various reference patterns. Artificial Neural Networks (ANN) were also applied to eliminate the false-positive candidates. The sensitivity and the number of false-positives were 73% and 11FPs per image on chest radiogram CAD and 77% with 2.6 FPs per image on helical CT scan CAD. These preliminary results imply that the GA and ANN based detective methods may be effective to indicate lesions on chest radiograms and helical CT scans.

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記述言語：日本語   出版者・発行元：日本医用画像工学会  

DOI： 10.11409/mit.16.103

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その他リンク： http://search.jamas.or.jp/link/ui/1998177115

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE COMPUTER SOC  

The purpose of this study is to apply a genetic-algorithm (GA) template-matching method to detect lung nodules in chest helical x-ray CT (computed tomography) images. We combined GA and template matching to search the positions of nodules and to calculate adaptation scales of individuals on GA, respectively. We used four simulated nodules created by Gaussian distribution, whose sizes were different each other, as reference patterns in the GA template matching. The GA selected an adequate reference image from four ones and searched adequate positions to template matching. We used cross-correlation as similarity of tmplate matching and as adaptation scales of individuals on GA. It was possible to detect 23 nodules from 45 ones that did not touch lung walls without consideration of their sizes. It was also possible to detect all nodules that touched lung walls by using conventional template matching along lung walls. The total detection rate was approximately 67%. The number of false positives per one slice was over 10. To improve the detection performance and to decrease the number of false positives, we are now working on considering operators and their parameters of GA.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：医用画像情報学会  

We are developing a computer-aided diagnostic system (CAD) which can detect masses and clustered microcalcifications on digital mammograms. In indicating the computer results to the physicians on an ordinary cathode-ray tube monitor, an automated windowing method has been applied to enhance the shadow of mammary glands. The area near the breast skin lines was difficult to evaluate, because most of pixel values in those areas were ignored by the method. Therefore, the improvement of contrast-correction process is required for the CAD. The purpose of this paper is to describe the dynamic-range compression technique which could make observers easier to recognize the regions in high and/or low density area, and is also to apply the method to the display stage of annotated images in our mammogram CAD.

DOI： 10.11318/mii1984.13.78

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総ページ数：153   記述言語：日本語

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総ページ数：1618   記述言語：日本語

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掲載種別：記事・総説・解説・論説等（その他）  

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記述言語：日本語   出版者・発行元：ニューサイエンス社  

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その他リンク： https://search.jamas.or.jp/link/ui/2019264912

記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

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記述言語：日本語   出版者・発行元：電子情報通信学会  

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記述言語：日本語   出版者・発行元：電子情報通信学会  

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記述言語：日本語   出版者・発行元：日本医用画像工学会  

本研究では、CR画像の総合画質改善を目的として、冗長型離散wavelet展開係数の改良処理により、ノイズの軽減とコントラストの向上を、同時に可能とする処理法を提案する。本提案法では、まず、対象画像にレベル2までの冗長型離散wavelet変換を施し、高周波成分の各レベル・各方向ごとの展開係数間で相関を求めた後、相関値にしきい値処理を施しノイズ除去を行う。次に、高周波成分を指数関数的に強調処理させ、画像のコントラスト改善を図る。本提案手法の優位性を検証するため、よく用いられる他の2手法と比較評価する。その結果、視覚的評価及び物理的評価とも、本提案法が優位であることが示され、提案手法がCR画像の画質改善に有効であることを示唆している。(著者抄録)

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

Modulation transfer function (MTF)やnoise power spectrum (NPS)などを用いたX線撮像系の客観的な評価は,receiver operating characteristic (ROC)解析などを用いた主観的な評価と必ずしも一致しない.また,MTFやNPSを臨床画像から求めることはできない.そこで,われわれは,定量的な複雑さのほかにヒトの視覚の周波数特性を含む指標系としてMTFフラクタル次元を医用X線撮像系に導入した.本研究では,淡い模擬腫瘤陰影を付加した胸部X線画像に対してMTFフラクタル次元の測定と観察者実験を実施した.その結果,二つの測定結果は同様の傾向を示した.これによりMTFフラクタル次元が医用X線画像の画質評価の一指標になり得る可能性が示唆されたものと考える.

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その他リンク： http://hdl.handle.net/20.500.12099/53321

記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

本研究では,不鋭な医用X線画像を自動認識する手法を提案する.その手法は,sobelフィルタを用いたエッジ検出,関心領域(ROI)の自動設定,特徴量計算,サポートベクターマシーンによる分類で構成される.本手法を14枚のファントム画像(正常画像7枚,不鋭画像7枚)と14枚の臨床画像(正常画像12枚,不鋭画像2枚)に適用した.その結果,ボケを含む画像とボケを含まない画像間の分類精度は,ファントム画像,臨床画像ともに100%であった.

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記述言語：日本語   出版者・発行元：新潟大学教育・学生支援機構  

平成23年度新潟大学組織的教育プログラム(新潟大学GP)医学部保健学科取組「学生と教員が学び鍛えあう保健学教育」は,医療を支える使命感と能力をもち,チーム医療に対応できる人材の育成をめざす2つの教育プログラムの実質化を進めた.保健学ヘの動機づけを図るプログラム「My confident lecture」では,新規科目「保健学総合」を初年次学生向けに開講し,学生参加型授業などの新しいタイプの授業の試みを行った.「保健学総合」を実践的に展開するプログラム「Our project study」では,少人数型の演習科目「保健学総合演習」の平成24年度開講をめざして模擬授業を試みた.それらの活動内容について,取組の課題とともに紹介する.

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記述言語：日本語   出版者・発行元：日本医用画像工学会  

近年、ウェーブレット変換を用いた医用画像のノイズ除去の諸手法が提案されている。本研究では、マンモグラムを対象として、離散ウェーブレット変換を用いた従来型のノイズ除去ならびに離散定常ウェーブレット変換を用いた2種類(従来型、改良型)のノイズ除去を行い、これら3手法の性能を検証する。使用するウェーブレット基底関数は、シミュレーション実験により物理特性評価で決定する。評価指標には、相互情報量、平均二乗誤差、信号雑音比の3つを用いる。性能の検証には、臨床画像実験による処理時間計測と視覚評価を行う。視覚評価には、シェッフェの一対比較中屋変法を用いる。結果は、演算時間が最速なのは、離散ウェーブレット変換を用いた従来型のノイズ除去法であったが、画質の面では離散定常ウェーブレット変換を用いた改良型ノイズ除去法が最良であった。(著者抄録)

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本医用画像工学会  

単純CTにおける急性期脳梗塞の診断では，虚血によるCT値低下に伴う灰白質と白質の境界の不明瞭化を同定することが重要である．しかし，CT画像上の量子ノイズの影響によって，その同定がしばしば困難となり，急性期脳梗塞の検出率が問題となっている．この問題を解決するために，我々は，適応型部分メディアンフィルタ（adaptive partial median filter: APMF）を提案した．そして，APMFの有用性を検証するため，シミュレーション画像と臨床画像を用いた評価実験を行ってきた．本稿では，APMFの概要とその性能，さらに臨床的有用性について実験結果を基に紹介する．

DOI： 10.11409/mit.30.231

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その他リンク： http://search.jamas.or.jp/link/ui/2013203999

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本放射線技術学会画像分科会  

DOI： 10.18973/cigjsrt.35.2_66

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本放射線技術学会画像分科会  

DOI： 10.18973/cigjsrt.35.1_82

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

コンピュータ支援診断(computer-aided diagnosis : CAD)の応用型のひとつとして自律型CADを提案する.自律型CADは,眼前の医用画像をコンピュータビジョン(computer vision : CV)で取り込み,その画像から異常部位を自動検出し,その結果を実空間へ還元できる独立駆動型のCADシステムである.自律型CADを実現するためには,医用画像中の異常部位の検出法,動画像からの医用画像領域の抽出アルゴリズムなどのいくつかの要素技術が必要である.我々はまずX線画像中の肺結節陰影を自動検出する手法を開発した.その検出法の性能評価のために60枚の胸部X線画像と20症例の胸部CT画像を用いた.これらの画像をモニタに表示しその画面を光学カメラで撮影した(CV画像).そして,原画像とCV画像に肺結節陰影の自動検出法をそれぞれ適用した.その結果,CV画像から肺結節陰影を自動検出した精度と原画像から自動検出した精度にほぼ差はみられなかった.次に我々は視線画像に対応するCV動画像から医用画像を認識する手法を開発した.その手法を30枚の胸部X線画像をシーンに含むCV動画に適用した結果,精度良く胸部X線画像の領域を認識することができた.これらの手法は,将来の自律型CADのための要素技術に発展していくものと考える.

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本医用画像工学会  

本論文では，単純CT画像における急性期脳梗塞の脳実質低吸収域の描出を目的としたZスコアマッピング法を紹介する．本手法は，ボクセル統計解析に基づき，入力画像の脳形態の標準化を行い，正常脳データベースを用いてボクセルごとにZスコア値を求め，低吸収域を視覚化する．急性期脳梗塞の患者21人に本手法を適用し，Zスコアを入力値として低吸収領域と正常領域のROC曲線を求めた結果，AUC値は0.834となり，本手法が低吸収域を視覚化できることが示された．さらに，神経放射線診断医による観察者実験を行った結果，画像診断時にZスコアマップを参考にすることによって低吸収域検出に関するAUC値が0.883から0.925に向上した．したがって，単純CT画像における急性期脳梗塞の低吸収領域の検出に関して，本手法が放射線科医の読影診断能力の向上に寄与できることが明確に示された．

DOI： 10.11409/mit.29.17

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）   出版者・発行元：日本放射線技術学会  

DOI： 10.6009/jjrt.66.1614

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00362227343?from=CiNii

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本放射線技術学会画像分科会  

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記述言語：日本語  

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本放射線技術学会  

抄録はありません．

DOI： 10.6009/jjrt.64.1000

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00317643914?from=CiNii

記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

頭部CT画像における急性期脳梗塞の存在判定アルゴリズムを一提案する.提案法では,適応型部分メジアンフィルタによって白質-灰白質のエッジを極力保ちながらノイズを低減した後,左右の脳実質領域の面積を多重しきい値で比較した.ルールベース,人工ニューラルネットワークで判別を行った結果,ROC曲線のA_z値はそれぞれ0.90,076となった.

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その他リンク： http://search.jamas.or.jp/link/ui/2008298848

記述言語：日本語   出版者・発行元：公益社団法人日本放射線技術学会  

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記述言語：日本語   出版者・発行元：公益社団法人日本放射線技術学会  

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記述言語：日本語   出版者・発行元：公益社団法人日本放射線技術学会  

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本放射線技術学会画像分科会  

DOI： 10.18973/cigjsrt.30.2_68

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本放射線技術学会画像分科会  

DOI： 10.18973/cigjsrt.30.1_79

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記述言語：英語   出版者・発行元：Springer New York  

This paper presents a simple and straightforward method for synthetically evaluating digital radiographic images by a single parameter in terms of transmitted information (TI). The features of our proposed method are: (1) simplicity of computation, (2) simplicity of experimentation, and (3) combined assessment of image noise and resolution (blur). Two acrylic step wedges with 0-1-2-3-4-5 mm and 0-2-4-6-8-10 mm in thickness were used as phantoms for experiments. In the present study, three experiments were conducted. First, in order to investigate the relation between the value of TI and image noise, various radiation doses by changing exposure time were employed. Second, we examined the relation between the value of TI and image blurring by shifting the phantoms away from the center of the x-ray beam area toward the cathode end when imaging was performed. Third, we analyzed the combined effect of deteriorated blur and noise on the images by employing three smoothing filters. Experimental results show that the amount of TI is closely related to both image noise and image blurring. The results demonstrate the usefulness of our method for evaluation of physical image quality in medical imaging.

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記述言語：日本語   出版者・発行元：公益社団法人日本放射線技術学会  

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記述言語：日本語   出版者・発行元：公益社団法人日本放射線技術学会  

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記述言語：日本語   出版者・発行元：公益社団法人日本放射線技術学会  

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記述言語：英語   出版者・発行元：一般社団法人電子情報通信学会  

We have developed a new recognition approach using 2nd order autocorrelation and multi-regression analysis to detect a small (<7mm in diameter) lung nodules in chest 3D CT images. By combining our previous detection method of the template matching based on genetic algorithm, the detection performance was 94% true-positive rate at 2.05 false-positive marks per case using leave-one-out study.

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記述言語：日本語   出版者・発行元：社団法人日本生体医工学会  

The purpose of this study is to develop a computerized scheme that allows discrimination between benign and malignant clustered microcalcifications, thus aiding radiologists to better interpret mammograms. The fuzzy-logic based genetic algorithm (GA-Fuzzy) that we propose is applied for the classification of mammographic microcalcifications. As a preprocess, microcalcification regions are extracted from images using mathematical morphology and other means. Then, four feature values including the number, area, circularity and minimum distance of microcalcifications are calculated for classification using GA-Fuzzy. In the GA-Fuzzy process, Gaussian-distributed membership functions are determined from the means and standard deviations of the feature values calculated from training images. Subsequently, the genetic algorithm optimizes the membership functions, and training is completed. Next, the feature values calculated from unknown images are input into GA-Fuzzy system to classify the image. Our scheme was tested utilizing the database of the Mammographic Image Analysis Society (MIAS), which contains 13 benign and 12 malignant microcalcification cases. Of the images, there are ten of each benign and malignant cases respectively used for training. The remaining five cases were used for classification as unknown images. Various combinations of sets are employed to obtain the results. The average accuracy of the GA-Fuzzy technique was approximately 81% (sensitivity, 85%; specificity, 77%). These results show that our scheme can be regarded as a useful technique to classify microcalcification cases.

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その他リンク： http://search.jamas.or.jp/link/ui/2004017840

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：医用画像情報学会  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：RADIOLOGICAL SOC NORTH AMERICA  

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記述言語：日本語   出版者・発行元：日本エム・イー学会  

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その他リンク： http://search.jamas.or.jp/link/ui/2003037691

記述言語：日本語  

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

われわれは遺伝的アルゴリズム(GA)を画像認識の探索部分に適用することによって, 広範囲な探索領域における濃淡画像のテンプレートマッチングを精度良く高速に行う手法を提案している.今まで用いられた画像はすべて2次元画像であった.そこで, 本稿では, より広範囲な探索領域をもつ医用3次元画像での探素を想定し, 提案している手法に基づいた画像認識アルゴリズムを3次元画像に適用することを検討した.その結果, シミュレーションにより3次元空間内における本手法の有効性を示した.また, その応用例として, 胸部ヘリカルCT画像における腫瘤陰影の検出に本手法を適用し, 良好な結果を得た.

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記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：英語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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