DR实际光野外影像成因的研究

目的:研究DR原始图像光野外的影像成因,减少患者辐射剂量,实现放射防护最优化。方法:分析原始图像光野外影像成因及射线来源,比较指示野与实际射线光野是否一致,外加遮线器以增加遮线器厚度减少漏线,使用自制可调手动遮线器对身体附近射线进行遮挡实验。结果:DR原始图像光野外影像是直射线方向产生的散射线照射到患者后在探测器形成的影像。结论:DR原始图像实际光野外影像是原发射线方向上的散射线照射到患者后,由于探测器(FD)比较灵敏,使患者肢体在探测器实际射线光野外形成的污渍影像,符合散射线"污渍效应"成像。

Factors Caused Image Outside of Actual Radiation Field in Digital Radiography

Objective To investigate the factors of the image outside of the actual radiation field in digital radiography and reduce the dose patient received, and to carry out the optimization of radiation protection. Factors caused image outside of actual radiation field in digital radiography and the source of X-ray were studied, and the uniformity between the direction field and the actual radiation field was compared. With additional light chopper, the thickness of the light chopper was increased to reduce the X-ray leakage. The self-made adjustable light chopper was used for the X-ray shielded experiment. The image outside of the actual radiation field was neither the signal which remained in the FPD after the last exposure, nor the result of the X-ray leakage from mismatched collimator. The image outside of the actual radiation field was the product of scattered radiation. The image outside of the actual X-ray field is produced by the scattered radiation that is in the same direction of primary radiation detected by the high sensitive FPD. With the self-made adjustable light chopper closed to the patients, the scattered X-ray can be shielded, the dose patient received can be reduced, and the image outside of the actual X-ray field can be reduced.