Medical Imaging Technology
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Volume 35 , Issue 2
Showing 1-9 articles out of 9 articles from the selected issue
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Main Topics / Challenges and Prospects for the Industry-Government-Academia Collaboration and the Medicine-Engineering Collaboration
Paper
  • Kazuya ABE, Hideya TAKEO, Yoshifumi KUROKI, Yuuichi NAGAI, Shigeru NAW ...
    Volume 35 (2017) Issue 2 Pages 110-120
    Released: March 27, 2017
    JOURNALS RESTRICTED ACCESS
    Aiming to compensate for the lack of case images in computer-aided diagnosis/detection (CAD) development, efforts have been made to artificially create case images by embedding lesions (such as tumors) into lesion-free images. We provide some examples of the usefulness of such images in liver tumor CAD, verified by judgment equipment that was designed using training data including artificial cases. For this study, we created an artificial case database (DB) made up of different variations, in consideration of practical use, proposing combinations and methods for generating optimal performance enhancement to unknown data in CAD. We created learning data for combinations that emphasized a lesion as the artificial case images with a variety of sizes and contrast changes, and we investigated methods of constructing optimal learning data, based on performance of the judgment equipment that we designed against unknown data, and we confirmed its effectiveness. In order to further confirm the generalizability of this technique with regard to application to other regions, we also confirmed that this is effective when applied to breast cancer tumor CAD. Additionally, we also propose using an artificial case DB as a performance evaluation measure for the various types of CAD. That is, for lesions (such as tumors) of standard size and contrast, we believe we can obtain objective evaluation criteria by comparing detection performance in response to quantitative changes in size and brightness.
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Tutorial
  • Keisuke FUJII
    Volume 35 (2017) Issue 2 Pages 121-125
    Released: March 27, 2017
    JOURNALS RESTRICTED ACCESS
    Various radiation dose quantities have been defined by ICRP (International Commission on Radiological Protection) and ICRU (International Commission on Radiation Units and Measurements) and the dose quantities should be properly used according to the purpose. In radiological practice, modality-specific dose indices are utilized, and the dose indices such as CTDI (computed tomography dose index) and DLP (dose length product) in x-ray CT examinations are used for the evaluation of x-ray output and quality control of CT scanners. The dose quantities such as organ dose and effective dose is used for the dose evaluation for patients in CT examinations. One of the methods of dose evaluation for patients is based on the measurements using small dosimeters implanted in various organ positions within an anthropomorphic phantom. Another method is based on Monte Carlo (MC) simulation of photon interactions within a computational phantom of human body and MC simulation for CT dose estimation requires information on the geometry of a CT scanner, scan parameters, and a computational phantom. This paper describes an outline of radiation dose quantities, dose indices used in CT examinations and methods of dose evaluation for the patients.
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Editors’ Note
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