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Active utilization of scatter for reducing patient dose in x-ray diagnosis

X射线诊断中积极利用散射减少患者剂量

基本信息

批准号：
02680184
负责人：
KANAMORI Hitoshi
金额：
$ 1.15万
依托单位：
Kyoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02680184/
关键词：
medical x-rays patient dose scattered x-rays x-ray spectrum lead collimator 鉛コリメ-タ

项目摘要

(1)Primary X-Ray Spectra and Their Effects Electron energy distribution was computed by the Monte-Carlo technique, and Bremsstrahlung spectra were calculated using quantum theory. The results coincided well with the results of the Birch-Marshall model. An efficient measurement method of x-ray spectra emitted by a self-rectified generator was performed. When an x-ray tube voltage ripple exceeded 60 %, the beam quality was hardened and the beam quantity increased, contrary to expectation. From these results it was found that the patient dose decreased as the tube current increased when a 2-pulse x-ray generator was used.(2)Measurement of Scattered X-Ray Spectrum An accurate measurement method of x-ray focal position was performed by using a pin-hole. As a result, accurate scatter spectra were obtained by using a conical lead collimator and beam stoppers.(3)Contrast-Dose Diagram Effects of the scattered x-rays upon the image quality were investigated by measuring the radiographic contrasts of aluminium square-wave chart images, with various scatter fractions. As a result, a contrast-dose diagram was proposed. This diagram is very useful to determine exposure conditions, balancing of high image quality and low patient dose in clinical radiography. This diagram was successfully applied in radiographing a pituitry fossa.

用蒙特-卡罗方法计算了电子的能量分布，用量子理论计算了韧致辐射谱。计算结果与Birch-Marshall模型的计算结果吻合较好。提出了一种有效的自整流发生器X射线能谱测量方法。当X射线管电压涟漪超过60%时，与预期相反，射束质量变硬并且射束量增加。从这些结果中发现，当使用2脉冲X射线发生器时，患者剂量随着管电流的增加而减少。（2）散射X射线光谱的测量采用针孔法对X射线焦点位置进行了精确测量。结果表明，使用锥形铅准直器和束流阻挡器获得了精确的散射光谱。（3）对比度-剂量图通过测量不同散射分数的铝方波图图像的对比度，研究散射X射线对图像质量的影响。据此，提出了一个对比剂量图。该图对于确定曝光条件、平衡高图像质量和低患者剂量非常有用。此图已成功地应用于垂体窝的X线摄影。