乳腺计算机X射线摄影自动曝光模式的校正

Studies on the calibration of mammography automatic exposure mode with computed radiology

目的 通过参照乳腺屏一片系统摄影自动曝光控制模式,对乳腺CR摄影自动曝光进行校正,从而实现影像质量与辐射剂量的最优化.方法 应用屏-片组合,28 kV条件下,对40 mm厚的有机玻璃进行自动曝光,以此所得曝光量（mAs）为基准,分10档分别采用±10 mAs的曝光量用CR进行曝光,选取LgM=2.0的曝光量作为基准,对CR的自动曝光模式进行校正.采用经校正后的CR自动曝光模式,分别采用26、28和30 kV对Fluke NA 18-220乳腺模体进行摄影,模体采用自动曝光控制（AEC）模式进行摄影,记录曝光量数值（mAs）,对CR影像进行处理.同时CR采用相同的kV和照射野及不同的曝光量对模体进行摄影.CR影像经后处理后请4位放射医师进行双盲阅片,按照美国放射学会（ACR）的评分标准评价打分.结果 采用稍高于传统屏-片组合的曝光量作为cR自动曝光校正基准值,可实现乳腺CR摄影自动曝光模式的校正,经校正后模体测试影像的评分均高于ACR的评分标准.结论 乳腺CR摄影自动曝光模式可根据CR特点进行校正,经校正后的乳腺CR摄影的自动曝光控制模式应用于临床既町明显降低病人辐射剂量,又可得到满足临床诊断需求的优质乳腺影像.

Objective To realize the optimization of image quality and radiation dose by correcting mammography automatic exposure,according to automatic exposure controlled mode of mammography film-screen system . Methods The film-screen system（28 kV） was applied to perform automatic exposure of plexiglass（40 mm） and get the standard dose of exposure, the exposure mode of CR base on LgM =2.0 was rectified, which was divided into 10 steps. Mammary glands pattern（Fluke NA18-220） were examined with CR（ 26,28, and 30 kV ） by the automatic exposure mode corrected. The exposure values（mAs） were recorded. CR image was diagnosed and evaluated in double blind way by 4 radiologists according to American Collage of Radiology（ACR） standard. Results Based on the standard of CR automatic exposure with the dose higher than the traditional exposure of film-screen system, the calibration of mammography automatic exposure was accomplished. The test results of the calibrated mode was better than the scoring system of ACR. Conclusions Comparative study showed improvement in acquiring high-quality image and reduction of radiation dose. The corrected mammography automatic exposure mode might be a better method for clinical use.