摘要
目的评价计算机摄影(CR)系统和普通屏-片系统两种方法拍摄直线加速器验证片的图像质量。方法自制透过率为6.45%的铅模体,用影像板(IP)和 X 线胶片分别拍摄放射治疗验证图片,利用刃边法绘制各自的调制传递函数(MTF)曲线。分别用 IP 和屏-片系统拍摄40例鼻咽癌患者的验证片,由2名相同年资的医师来判断每幅验证片岩骨破坏的程度,根据结果分别绘制2名医师关于 CR 照片和普通照片的受试者操作特性曲线(ROC)。结果 CR 系统和屏-片系统的鉴别频率分别为1.159和0.806 Lp/mm。医师1 CR 照片和普通照片 ROC 曲线下的面积(Az)值为0.802和0.742,医师2 CR 照片和普通照片 ROC 的 Az 值为0.751和0.600。CR 的 MTF 曲线和 ROC 曲线均高于屏-片系统。结论利用 CR 技术拍摄直线加速器射野验证片的图像质量优于屏-片系统,在临床上具有很大推广价值。
Objective To evaluate the quality of the portal images acquired by computed radiography （CR） system and conventional, screen-film system, respectively. Methods Imaging plates （IP） and X-ray films of a home-devised lead phantom with a leakage of 6. 45% were acquired, and modulation transfer function （MTF） curves of the both images were measured using edge method. Portal images of 40 nasopharyngeal cancer patients were acquired by IP and screen-film system respectively. Two doctors with similar experience evaluated the damage degree of petrosal bone, the receiver operating characteristic （ ROC ） curve of CR images and general images were drawn according to two doctors evaluation results. Results The identification frequency of CR system and screen-film system were 1. 159 and 0. 806 Lp/mm respectively. For doctor one, the area under ROC curve of CR images and general images were 0. 802 and 0. 742 respectively. For doctor two, the area under ROC curve of CR images and general images were 0. 751 and 0. 600 respectively. The MTF curve and ROC curve of CR are both better than those of screen-film system. Conclusion The image quality of CR portal imaging is much better than that of screen-film system. The utility of CR in linear accelerator for portal imaging is premising in clinic.
出处
《中华放射学杂志》
CAS
CSCD
北大核心
2007年第2期128-130,共3页
Chinese Journal of Radiology
