Study of measuring system of x-ray spectrum for reduction of patient dose at medical x-ray diagnosis.

医学X射线诊断中降低患者剂量的X射线能谱测量系统研究

• 批准号: 08672583
• 负责人: MATSUMOTO Masao
• 金额: $ 1.47万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08672583/
• 关键词: CdTe detector; CdZnTe detector; stripping procedure; diagnostic x-ray spectrum; photon spectrum

(1) Correction of diagnostic x-ray spectra measured with CdTe and CdZnTE detectorsWe have attempted to perform the direct measurement of diagnostic x-ray spectra using low-cost CdTe and CdZnTe detectors, which have been developed recently. Since detected spectra did not coincide with the true photon spectra, a correction by stripping procedure was applied. The results obtained with CdTe detector were less exact than those with a Ge detector, but those with CdZnTe detector agreed with it.We analyzed mammographic x-ray spectra penetrated through 0.03mmMo or 0.025mmRh filter and objects measured using 50-mu m pinhole colimator system at 28kV and 50mAs. The obtainable results with CdZnTe detector agree with mammographic x-ray spectral shape measured using Ge detector published by Bureau of Radiological Health (BRH) in U.S.A..(2) Measurement of scattered x-ray spectraBy using a conical collimator and a lead beam stopper, primary and scattered x-ray photon spectra through an object and an an … More ti-scatter grid (abbreviated as grid, hereafter) were measured separately, varying the irradiation field area. From these results, the effects of grids for removing scattered x-rays were able to estimate.(3) Analysis of optimum radiographic factorsWe proposed a new method for determining the optimum tube voltage of a chest radiograph using psychophysical analysis. An optimum tube voltage, by which the highest density in the lung-field and the lowest density in the mediastin just covered the optimum density range, was obtained using x-ray photon spectrum and sensitivity spectrum of the screen.(4) Analysis of image quality (MTF,granularity) of a screen-film systemWe have obtained the tube voltage dependence of the modulation transfer function (MTF) of a rate-erath screen-film system. The values of the MTFs for the front and back sides at spatial frequencies of less than 3mm^<-1> decreased with the tube voltage. We showed that to explain this phenomenon, not only K-x rays but coherent and incoherent scattered x-ray photons yielded in the screens had to be taken into consideration.The value of psychophysical Wiener spectrum at a frequency of 2.0mm^<-1> can be used for the evaluation of radiographic mottle instead of the psychophysical RMS granularity. The time to obtain the psychophysical Wiener spectrum can be reduced more than it to obtain the psychophysical RMS granularity. Less

(1)用CdTe和CdZnTe探测器测量的诊断X射线光谱的校正我们尝试使用最近开发的低成本的CdTe和CdZnTe探测器直接测量诊断X射线光谱。由于检测到的光谱与真实的光子光谱不一致，采用了剥离过程进行修正。分析了用0.03 mm Mo或0.025 mm Rh滤光片和50 mA针孔测量仪测量的乳腺X-射线能谱。(2)用锥形准直器和铅束阻挡器测量物体和…中的初级和散射X射线能谱分别测量了更多的钛散射栅格(以下简称栅格)，改变照射野面积。根据这些结果，可以估计网格对去除散射X射线的效果。(3)最佳摄影因素分析我们提出了一种新的方法来确定胸片的最佳管压。利用X射线光子能谱和屏幕的灵敏度谱，得到了一个最佳的管电压，在该电压下，肺野的最高密度和介质中的最低密度正好覆盖了最佳密度范围。(4)屏幕-胶片系统的图像质量(MTF，粒度)分析我们得到了速率-速度-屏幕-胶片系统的调制传递函数(MTF)与管电压的关系。在空间频率小于3 mm^~(-1)~(-1)的情况下，正反面的MTF值随管电压的增大而减小。结果表明，为了解释这一现象，不仅要考虑K-x射线，还必须考虑屏幕中产生的相干和非相干散射x射线光子。在2.0 mm的频率下，心理物理Wiener谱值可以代替心理物理均方根粒度来评估射线斑点。获得心理物理维纳谱的时间比获得心理物理均方根粒度的时间要少得多。较少

项目成果

A.Takigawa: "Effects of anti-scatter grids on x-ray spectrum and radiographic contrast" Journal of Photographic Science. 44-3. 93-98 (1996)

A.Takikawa：“抗散射网格对 X 射线光谱和射线照相对比度的影响”摄影科学杂志。

H.Arimura: "Tube voltage dependence of modulation transfer function for a rare-earth screen-film system" Journal of The Society of Photographic Science and Technology of Japan. 60-3. 177-181 (1997)

H.Arimura：“稀土屏幕胶片系统的调制传递函数的管电压依赖性”日本摄影科学技术学会杂志。

Y.Asai: "Optimum tube voltage of chest radiographs obtained by psychophysical analysis" Journal of The Society of Photographic Science and Technology of Japan. 60-3. 189-195 (1997)

Y.Asai：“通过心理物理学分析获得的胸部X光照片的最佳管电压”日本摄影科学技术学会杂志。

有村秀孝、松本政雄他6名: "X-ray tube voltage dependence of Wiener spectra of guantum mottle obtained by determining detective guantum efficiencies of a screen" Optical Engineering. 35・4. 926-937 (1996)

Hidetaka Arimura、Masao Matsumoto 等 6 人：“通过确定屏幕的检测量子效率获得的量子斑点的维纳光谱的 X 射线管电压依赖性”光学工程 35・4（1996）。

尾崎吉明: "検出能と撮影能率を考慮した軟X線写真の最適撮影条件" 日本写真学会誌. 60・3. 189-195 (1997)

Yoshiaki Ozaki：“考虑检测能力和成像效率的软X射线摄影的最佳成像条件”日本摄影学会杂志60・3（1997）。