多层放射性铬胶片剂量验证系统的研制

目的：采用放射性铬胶片（RCF）快速准确地验证调强放射治疗（IMRT）形成的复杂剂量分布，研制多层RCF剂量验证系统。方法：以RCF为载体，利用测量模体、RCF、胶片扫描仪及验证软件的剂量验证系统实施测量及分析；模体模拟人体外形，包含多种专用模块，软件包含二维、三维无标记点配准及验证分析功能。结果：模体凸凹槽结构结合软件无标记点自动定位功能，可快速完成胶片的固定及其与计划数据的配准以及RCF的免冲洗自动显影，减少了调强放射治疗测量和分析的不确定因素，减少物理师工作量。患者调强验证以剂量偏差3%和3 mm距离偏差为控制标准，6个临床病例的伽马分析通过率均＞90%。结论：多层RCF剂量验证系统是调强适形放射治疗剂量验证和常规质量保证的多用途工具，具有方便、准确、真实、海量信息及多用途等特点，可用于对直线加速器、伽玛刀、射波刀、后装机及粒子植入等放射治疗设备质量验证和调强治疗患者剂量的二维、三维验证。

Development of multi-layer radiochromic film dose verification system

Objective： Multifilm QA（Quality Assurance） system is developed to guarantee the quality of radiotherapy, and verify the dose distribution of IMRT more accurately. Methods：Radiochromic film is used as carrier and the dose analysis system is composed of phantom, radiochromic film, film scanner and analysis software. The phantom is shaped as human body, and it consists of appropriative modules for ionization chamber, film and MOSFET dosimeters and inhomogeneous module containing lung and bone density inserts. Software provides unique functions in 2D and 3D registering and analyzing, facilitates plan verifications and routine quality assurance programs. Results：The tongue and groove joint and the automatic register function make the film fixing and register convenient. Combined with the self-developed radiochromic film, the uncertainties in measurement and analysis are reduced, and physicist＆#39;s workload is also diminished. The gamma index passing rate for 6 cases are all over 90%with 3% dose difference and 3mm DTA criteria. The system can be used for the machine QA, such as linear accelerator, gamma knife, cyber knife, afterloading unit, interstitial brachytherapy as well as the patient specific 2D and 3D IMRT plan QA. Conclusion：Multifilm QA system is a versatile tool for IMRT dose verification and regular quality assurance. It is convenient, accurate, authentic, huge amounts of information and multi-purpose, etc. It can be used in the dose verification for VMAT and IMRT plan besides daily quality assurance of accelerator.