EBT3胶片在重离子质量控制中的应用  

Application of EBT3 Film in Heavy Ion Quality Control

作　　者：王紫珩 马霄云 叶延程 张雁山 寇海瑞 吴晓思 WANG Ziheng;MA Xiaoyun;YE Yancheng;ZHANG Yanshan;KOU Hairui;WU Xiaosi(Department of Medical Physics,Gansu Wuwei Tumor Hospital,Wuwei Gansu 733000,China;Department of Radiation Oncology,Gansu Wuwei Tumor Hospital,Wuwei Gansu 733000,China)

机构地区：[1]甘肃省武威肿瘤医院放射治疗物理室,甘肃武威733000 [2]甘肃省武威肿瘤医院放射治疗科,甘肃武威733000

出　　处：《中国医疗设备》2024年第12期39-45,共7页China Medical Devices

基　　金：中央引导地方科技发展资金项目(22ZY1QH001);武威市青年科技基金项目(WW2202RPQ041)。

摘　　要：目的分析EBT3胶片对重离子射束的响应特性,探索其在重离子质量控制中的应用。方法对EBT3胶片分别使用6 MV光子与不同能量重离子束进行刻度,引入标准净光密度分析方法,研究EBT3胶片对重离子射束的剂量响应。使用EBT3胶片对重离子射野、束斑以及重离子峰位、虚拟源轴距进行测量,并将结果与PTW 1500XDR电离室矩阵以及电离室测量结果进行对比。结果使用净光密度分析法对EBT3胶片进行剂量刻度,重离子线性能量传递(Linear Energy Transfer,LET)值范围为12.660~19.071 keV/μm,胶片净光密度范围为0.05~0.40,胶片对碳离子束剂量响应为光子的85.71%~95.62%。在射程测量中,相较于PTW 34070-34080电离室,剂量响应为39.43%~85.88%。在射野平坦度测量中,相较于PTW 1500XDR电离室矩阵,矩阵偏差为-0.50%±1.13%,射野大小偏差为4.1 mm。结论研究结果显示,碳离子束的胶片剂量响应受LET值的影响,仅能在特定条件下应用于绝对剂量的测量,多数情形下仅可用于相对值与强度的测量。然而,鉴于胶片结果具有直观性和极高的空间分辨率,部分测量结果更具参考意义。在重离子设备的质量控制过程中,合理运用该测量结果能够显著提升工作效率与准确性。Objective To analyze the response characteristics of EBT3 film to heavy ion beam and explore its application in heavy ion quality control.Methods The EBT3 film was irradiated by 6 MV photons and heavy ion beams of various energies.The net optical density analysis method was introduced to explore the dose-response of the EBT3 film to heavy ion beams.The EBT3 film was utilized to measure the heavy ion field,beam spot,heavy ion peak position and virtual source wheelbase,and the results were compared with PTW 1500XDR ionization chamber matrix and Markus ionization chamber.Results Dose calibration of EBT3 film was performed using net optical density analysis.The range of heavy ion linear energy transfers(LET)was 12.660-19.071 keV/μm,and the range of film net optical density was 0.05-0.40.The dose response of the film to carbon ion beam was 85.71%-95.62%of photons.In the range measurement,compared with PTW 34070-34080 ionization chamber,the dose response was 39.43%-85.88%.In the measurement of field flatness,compared with the PTW 1500XDR ionization chamber,the matrix deviation was-0.50%±1.13%,and the deviation of field size was 4.1 mm.Conclusion The study reveals that the EBT3 film dose-response of carbon ion beams is affected by the LET value and can only be used for absolute dose measurement under specific conditions.In most cases,the EBT3 film can only be used for the measurement of intensities and relative values.However,considering the intuitive nature and high spatial resolution of film results,some of the measurement results are more useful for reference,and it can be employed in the quality control of heavy ion facilities to enhance work efficiency and accuracy.

关 键 词：EBT3胶片 净光密度 重离子 剂量响应 线性能量传递(LET) 质量控制 

分 类 号：R197.39[医药卫生—卫生事业管理] R318.6[医药卫生—公共卫生与预防医学]