辐射着色胶片XR-RV3和EDR2的剂量学性能比较

Comparison of dosimetric characteristics of two radiochromic films （XR-RV3 and EDR2）

目的 比较两种用于介入放射学程序中患者峰值皮肤剂量测量的胶片性能,包括胶片的灰度随时间变化、灵敏度、能量响应、剂量响应等特性.方法 分别在60、80、100、120和140 kV5档管电压下自由空气中照射GafChromic XR-RV3胶片和KODAK EDR2胶片800 mGy剂量,测量结果归一到80 kV分析胶片的能量响应.在模体上用80 kV管电压分别照射两种胶片0.025～10 Gy剂量,分析胶片的灵敏度和剂量响应.采用Epson V750平板扫描仪对两种胶片进行扫描分析,分另测量图像的红、绿、蓝3色通道的像素值.结果 在灰度随时间变化上,XR-RV3胶片在照射后的24 h内灰度的变化为2％,在72 h内为4％,在6周内为6％；低剂量时EDR2胶片比XR-RV3胶片更灵敏；能量响应方面,在放射诊断能量范围内,XR-RV3胶片的能量响应在9％以内,EDR2胶片的能量响应在23％以内；在0.025 ～10 Gy的剂量范围内,对于XR-RV3胶片,红光通道随剂量的变化曲线的响应最明显.对于EDR2胶片,3种颜色通道的像素值曲线重合,EDR2胶片在接受剂量超过500 mGy时达到饱和.结论 XR-RV3胶片在灰度变化、能量响应、剂量响应等方面要优于EDR2胶片,非常适和用于介入放射学程序中患者峰值皮肤剂量的测量和分析.

Objective To study the dosimetric characteristics of two different radiochromic films used to estimate peak skin dose（PSD） of patients.The characteristics of these two films were investigated and compared after exposure to ionizing radiation in the diagnostic energy range,including post-exposure gray growth,sensitivity,energy dependence and dose response.Methods GafChromic XR-RV3 film and KODAK EDR2 film were exposed to air kerma 800 mGy free-in-air using five X-ray beam qualities （60,80,100,120 and 140 kVp） in a SSDL.The measurement for each energy was normalized to 80 kV to analyze energy dependence of films.The films were calibrated to different dose level （0.025-10 Gy） onphantom by 80 kV X-rays.The response curve were plotted to analyze sensitivity and dose response.The films were scanned with Epson V750 commercial flatbed scanner.Color channel analysis was performed.Results The post-exposure gray growth of XR-RV3 film was found to be fairly stable.The change were 2％,4％,6％ at 24 h,72 h and 6 weeks after exposure respectively.EDR2 film was found to be more sensitivity than XR-RV3 film in low dose.The energy response of the XR-RV3 film and EDR2 film were within 9％ and 23％ over the clinical diagnostic x-ray energies,respectively.In the dose range of 0.025-10 Gy,for the XR-RV3 film,the red channel with the dose response curve was most obvious.For EDR2 film,the pixel value of three color channels was coincident.The EDR2 film appeared to be saturated when receiving doses greater than 500 mGy.Conclusions The XR-RV3 film is superior to EDR2 film in gray growth,energy dependence,dose-response and other aspects.This film is very suitable for measuring and analyzing PSD of patients in interventional radiology procedures.