| Project/Area Number |
17590452
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Medical sociology
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| Research Institution | Osaka University |
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Principal Investigator |
MATSUMOTO Masato Osaka University, Graduate School of Medicine, Associate Professor, 医学系研究科, 助教授 (50149944)
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| Co-Investigator(Kenkyū-buntansha) |
OGATA Yuji Osaka University, Graduate School of Medicine, Assistant, 医学系研究科, 助手 (60281127)
MAEDA Koji Hiroshima International University, Dep.Of Clinical Radiology, Assistant, 保健医療学部, 助手 (20330706)
KUBOTA Hideaki Suzuka Univ.of Medical Science, Dep.Of Medical Engineering, Associate Professor, 医用工学部, 助教授 (30234496)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Digital mammographic x-ray unit / Spectral measurement system / Carbon or acrylic resin scatterer / Digital characteristic curve / Modulation Transfer Function (MTF) / Wiener spectrum / C-D phantom image / Quality control system / ディジタルマンモグラフィシス / CDMAMファントム / 平均乳腺線量 / ディジタル画像の物理特性 / 被曝線量 / 検出能 |
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| Research Abstract |
The analysis of x-ray spectra is important for quality assurance (QA) and quality control (QC) of radiographic systems. The aim of this study is to measure the digital mammographic x-ray spectra under clinical conditions using a high-resolution Schottky, CdTe detector. Under clinical conditions, the direct measurement of a mammographic spectrum is difficult because of the high photon fluence rates that cause significant detector photon pile-up. An alternative way of measuring the output spectra from a tube is first to measure the 90-degree Compton scattered photons from a given sample. With this set-up detector pile-up is not a problem. From the scattered spectrum one can then use an energy correction and the Klein-Nishina function to reconstruct the actual spectrum incident upon the scattering sample. The verification of whether our spectra measured by the Compton method are accurate was accomplished by comparing exposure rates calculated from the reconstructed spectra to those measur
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ed with an ionization chamber. We used aluminum (Al) filtration ranging in thickness from 0 to 0.8 mm. The difference rates to the dosimeter of the half-value layers (HVLs) obtained for a 27 kV beam were 17.5 % for carbon scatterer and 16.5 % for acrylic resin scatterer. For a 32 kV beam we obtained 12.8 % and 11.4 %. The small differences in HVLs obtained by both techniques suggest that Compton scatter spectroscopy with a high-resolution Schottky CdTe detector is suitable for measuring the digital mammographic x-ray spectra and useful for QA and QC of clinical digital mammographic x-ray equipment.
Evaluation standard of phantom images in mammography guideline (second edition) published on March, 2004 including film outcome of digital images was indicated and evaluation of physical imaging properties (digital characteristic curve, modulation transfer function, noise power (Wiener) spectrum, detective quantum efficiency, detectorbility of CDMAM phantom) of digital mammography was explained. Less
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