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Effects of scattered X-rays on diagnostic X-ray images

散射 X 射线对诊断 X 射线图像的影响

基本信息

批准号：
12650058
负责人：
TAKIGAWA Atsushi
金额：
$ 1.09万
依托单位：
Hiroshima Prefectural College of Health Sciences
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650058/
关键词：
scattered X-rays image sharpness anti-scatter grid air-gap method patient dose

项目摘要

We studied three subjects. Firstly, we evaluated the effect of scattered X-rays on the sharpness of X-ray image. Secondly, we compared the elimination efficiency of scattered X-rays for air-gap method and anti-scatter grid method. Thirdly, we evaluated the performance of dosimeter for measuring patient dose.1. It has been said that the response function of scattered X-rays agree with the primary fraction, when scattered X-rays incident in wide area of the image receptor. However, no report which confirmed the fact has been published as long as we know. We conducted the experiment using square wave chart. As a result, we confirmed the fact.2. Air-gap method and anti-grid method are often used to eliminate scattered X-rays. However, it is nots clear that which method should be used in radiography. We measured scatter fraction, radiographic contrast and surface dose, changing the thickness of the object, field area, distance of air-gap and anti-scatter grid. As a result, it is clarified that air-gap method is useful when the field area is small enough, nevertheless we must consider how wide the field area is required for diagnosis.3. Patient dose due to X-ray fluorography has been increased according to the rise in the number of patients who are treated with interventional radiology. For measuring patient surface dose including scattered X-rays in fluorography, some dosimeters have been developed. Skin dose monitor is one of them. We evaluated the performance of the skin dose monitor. It underestimates surface dose when short period fluorography is repeated comparing to one continuous exposure, even total exposure time is the same. We cannot measure surface dose correctly, when X-rays get in the detector in large angle. However, skin dose monitor is very useful to measure surface dose in real time, we hope it will be improved in the near future.

我们学习了三门科目。首先，我们评估了散射x射线对x射线图像清晰度的影响。其次，比较了气隙法和反散射网格法对散射x射线的消除效率。第三，对剂量计测量患者剂量的性能进行了评价。已经说过，当散射x射线入射在图像受体的宽区域时，散射x射线的响应函数与初级分数一致。然而，据我们所知，没有任何报道证实这一事实。我们用方波图进行了实验。结果，我们证实了事实。消除散射x射线常采用气隙法和反栅格法。然而，目前尚不清楚放射照相应采用哪种方法。通过改变物体的厚度、场面积、气隙距离和防散射网格，测量散射分数、x线造影剂和表面剂量。结果表明，当场面积足够小时，气隙法是有用的，但我们必须考虑诊断所需的场面积有多宽。随着接受介入放射治疗的患者数量的增加，x线透视的患者剂量也随之增加。为了测量病人的表面剂量，包括在荧光摄影中的散射x射线，研制了一些剂量计。皮肤剂量监测仪就是其中之一。我们评估了皮肤剂量监测仪的性能。与一次连续照射相比，即使总照射时间相同，重复短周期荧光照相也会低估表面剂量。当x射线以大角度进入探测器时，我们无法正确测量表面剂量。然而，皮肤剂量监测仪是非常有用的，可以实时测量表面剂量，我们希望在不久的将来改进它。