Division of Radiation Oncology, National Cancer Centre Singapore, Singapore, Singapore.
Department of Oncology, University of Cambridge, UK.
Technol Cancer Res Treat. 2024 Jan-Dec;23:15330338241262610. doi: 10.1177/15330338241262610.
A daily quality assurance (QA) check in proton therapy is ensuring that the range of each proton beam energy in water is accurate to 1 mm. This is important for ensuring that the tumor is adequately irradiated while minimizing damage to surrounding healthy tissue. It is also important to verify the total charge collected against the beam model. This work proposes a time-efficient method for verifying the range and total charge of proton beams at different energies using a multilayer Faraday collector (MLFC).
We used an MLFC-128-250 MeV comprising 128 layers of thin copper foils separated by thin insulating Kapton layers. Protons passing through the collector induce a charge on the metallic foils, which is integrated and measured by a multichannel electrometer. The charge deposition on the foils provides information about the beam range.
Our results show that the proton beam range obtained using MLFC correlates closely with the range obtained from commissioning water tank measurements for all proton energies. Upon applying a range calibration factor, the maximum deviation is 0.4 g/cm. The MLFC range showed no dependence on the number of monitor units and the source-to-surface distance. Range measurements collected over multiple weeks exhibited stability. The total charge collected agrees closely with the theoretical charge from the treatment planning system beam model for low- and mid-range energies.
We have calibrated and commissioned the use of the MLFC to easily verify range and total charge of proton beams. This tool will improve the workflow efficiency of the proton QA.
质子治疗中的日常质量保证 (QA) 检查是确保每个质子束能量在水中的射程准确到 1 毫米。这对于确保肿瘤得到充分照射，同时最大限度地减少对周围健康组织的损伤非常重要。验证与束模型相对应的总收集电荷量也很重要。这项工作提出了一种使用多层法拉第收集器 (MLFC) 验证不同能量质子束射程和总电荷量的高效方法。
我们使用了一个由 128 层薄铜箔组成的 MLFC-128-250 MeV，这些铜箔通过薄的绝缘 Kapton 层隔开。穿过收集器的质子会在金属箔上产生电荷，这些电荷被多通道静电计积分和测量。箔片上的电荷沉积提供了关于束射程的信息。
我们的结果表明，使用 MLFC 获得的质子束射程与使用 commissioned water tank 测量获得的所有质子能量的射程密切相关。应用射程校准因子后，最大偏差为 0.4 g/cm。MLFC 射程与监测单位数量和源皮距无关。在多个星期内收集的射程测量结果表现出稳定性。收集的总电荷量与治疗计划系统束模型的理论电荷量非常吻合，适用于低能和中能。
我们已经校准并委托使用 MLFC 来轻松验证质子束的射程和总电荷量。该工具将提高质子 QA 的工作流程效率。
