Advanced Radiochromic Film Based Dosimetry Techniques in Radiation Therapy and Diagnostic Radiology

放射治疗和诊断放射学中基于先进放射变色胶片的剂量测定技术

• 批准号: RGPIN-2015-04382
• 负责人: Devic, Slobodan
• 金额: $ 2.04万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612931
• 关键词: Advanced; Radiochromic; Film; Based; Dosimetry

Film dosimetry was developed into a powerful tool for radiotherapy treatment verification and quality assurance. Introduction of radiochromic film having all advantages of film dosimetry without the need for wet processors make this film type an important dosimetric tool. The EBT film model has been introduced as a more sensitive alternative to the earlier MD-55 model. Active layer of subsequent EBT2 model contains a yellow marker dye added by manufacturer to correct for subtle differences in active layer thickness. During previously NSERC funded grant we have substantially improved the energy response of the latest EBT3 radiochromic film model, which also has a symmetric structure and embedded anti-Newton rings feature within protecting polyester layers. As part of future projects, we will extend the use of various radiochromic film models to currently emerging advanced applications. XR-QA film model (sensitive layer with high atomic Z materials) provided promising initial results for eventual in vivo and reference dosimetry at low kVp energy range photons used in diagnostic radiology. The latest XR-QA2 film model exhibits significant energy dependent dose response even in relatively narrow range of beam qualities used in diagnostic radiology. Following our success in improving energy dependent dose response of the EBT3 film model, we will investigate possible changes in chemical composition of the XR-QA2 film model sensitive layer to decrease its energy dependence. We will also focus on the use of radiochromic film strips for CTDI measurements. In contrast to pencil type ionization chamber measurements, proposed method requires only one exposure and does not need stem effect correction. Also, we will make radiochromic film based CTDI measurements part of QA program in both radiotherapy and diagnostic radiology departments in our hospital. Third objective will focus on the development and clinical applications of the EBT3 film model for both machine and patient-specific based QA in brachytherapy. Lack of clinical measurements and patient-specific QA procedures (similar to those in IMRT) in high dose rate brachytherapy are tempted to be developed in order to improve both the QA program and patient safety during brachytherapy procedures. As a result of this project, we are hoping to conclude on DD/DTA parameters that can be recommended for brachytherapy QA. Finally, we will concentrate on establishment of radiochromic film dosimetry protocols in low energy proton beams (using HD-V2 film model) for radio-biological experiments (cell and small animal irradiations), proton based intraoperative radiotherapy and for treatment of skin diseases (Melanomas, Eczema, Infectious Acne). Reference dosimetry film measurements (based on cross-calibration with graphite calorimeter) will be used to measure setup specific output measurements for radiobiological irradiations.

胶片剂量测定已发展成为放射治疗验证和质量保证的强大工具。放射变色薄膜的引入具有薄膜剂量测定的所有优点，无需湿处理机，使这种薄膜类型成为重要的剂量测定工具。 EBT 胶片型号已推出，作为早期 MD-55 型号的更灵敏的替代品。后续 EBT2 模型的活性层包含制造商添加的黄色标记染料，以纠正活性层厚度的细微差异。在之前的 NSERC 资助期间，我们大幅改进了最新 EBT3 放射变色薄膜模型的能量响应，该模型还具有对称结构，并在保护聚酯层内嵌入了反牛顿环功能。 作为未来项目的一部分，我们将把各种放射变色薄膜模型的使用扩展到当前新兴的高级应用。 XR-QA 胶片模型（具有高原子 Z 材料的敏感层）为诊断放射学中使用的低 kVp 能量范围光子的最终体内和参考剂量测定提供了有希望的初步结果。即使在诊断放射学中使用的相对较窄的光束质量范围内，最新的 XR-QA2 胶片模型也表现出显着的能量依赖性剂量响应。在我们成功改善 EBT3 薄膜模型的能量依赖性剂量响应之后，我们将研究 XR-QA2 薄膜模型敏感层的化学成分可能发生的变化，以减少其能量依赖性。 我们还将重点关注放射变色胶片条在 CTDI 测量中的使用。与铅笔型电离室测量相比，所提出的方法仅需要一次曝光，并且不需要干效应校正。此外，我们还将把基于放射性变色胶片的 CTDI 测量作为我们医院放射治疗和诊断放射科 QA 计划的一部分。 第三个目标将重点关注 EBT3 胶片模型的开发和临床应用，用于近距离放射治疗中基于机器和患者特定的 QA。为了改善近距离放射治疗过程中的 QA 计划和患者安全，高剂量率近距离放射治疗中缺乏临床测量和患者特定的 QA 程序（类似于 IMRT 中的那些），因此很容易被开发出来。作为该项目的结果，我们希望得出可推荐用于近距离放射治疗 QA 的 DD/DTA 参数。 最后，我们将集中精力建立低能质子束放射变色胶片剂量测定方案（使用 HD-V2 胶片模型），用于放射生物学实验（细胞和小动物照射）、基于质子的术中放疗和皮肤病（黑色素瘤、湿疹、传染性痤疮）的治疗。参考剂量测定胶片测量（基于与石墨量热计的交叉校准）将用于测量放射生物辐射的设置特定输出测量。