Bobić Mislav, Christensen Jeppe B, Lee Hoyeon, Choulilitsa Evangelia, Czerska Katarzyna, Togno Michele, Safai Sairos, Yukihara Eduardo G, Winey Brian A, Lomax Antony J, Paganetti Harald, Albertini Francesca, Nesteruk Konrad P
Department of Physics, ETH Zurich, Zurich, Switzerland.
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.
Front Oncol. 2024 Jan 8;13:1333039. doi: 10.3389/fonc.2023.1333039. eCollection 2023.
To demonstrate the suitability of optically stimulated luminescence detectors (OSLDs) for accurate simultaneous measurement of the absolute point dose and dose-weighted linear energy transfer (LET) in an anthropomorphic phantom for experimental validation of daily adaptive proton therapy.
A clinically realistic intensity-modulated proton therapy (IMPT) treatment plan was created based on a CT of an anthropomorphic head-and-neck phantom made of tissue-equivalent material. The IMPT plan was optimized with three fields to deliver a uniform dose to the target volume covering the OSLDs. Different scenarios representing inter-fractional anatomical changes were created by modifying the phantom. An online adaptive proton therapy workflow was used to recover the daily dose distribution and account for the applied geometry changes. To validate the adaptive workflow, measurements were performed by irradiating AlO:C OSLDs inside the phantom. In addition to the measurements, retrospective Monte Carlo simulations were performed to compare the absolute dose and dose-averaged LET (LET) delivered to the OSLDs.
The online adaptive proton therapy workflow was shown to recover significant degradation in dose conformity resulting from large anatomical and positioning deviations from the reference plan. The Monte Carlo simulations were in close agreement with the OSLD measurements, with an average relative error of 1.4% for doses and 3.2% for LET. The use of OSLDs for LET determination allowed for a correction for the ionization quenched response.
The OSLDs appear to be an excellent detector for simultaneously assessing dose and LET distributions in proton irradiation of an anthropomorphic phantom. The OSLDs can be cut to almost any size and shape, making them ideal for in-phantom measurements to probe the radiation quality and dose in a predefined region of interest. Although we have presented the results obtained in the experimental validation of an adaptive proton therapy workflow, the same approach can be generalized and used for a variety of clinical innovations and workflow developments that require accurate assessment of point dose and/or average LET.
证明光激励发光探测器（OSLD）适用于在人体模型中准确同时测量绝对点剂量和剂量加权线能量转移（LET），以对每日自适应质子治疗进行实验验证。
基于由组织等效材料制成的人体头颈部模型的CT创建临床实际的调强质子治疗（IMPT）治疗计划。IMPT计划通过三个射野进行优化，以向覆盖OSLD的靶区递送均匀剂量。通过修改模型创建代表分次间解剖结构变化的不同场景。使用在线自适应质子治疗工作流程来恢复每日剂量分布并考虑所应用的几何变化。为了验证自适应工作流程，通过照射模型内的AlO:C OSLD进行测量。除了测量之外，还进行了回顾性蒙特卡罗模拟，以比较递送至OSLD的绝对剂量和剂量平均LET（LET）。
在线自适应质子治疗工作流程显示可恢复因与参考计划存在较大解剖结构和定位偏差而导致的剂量适形性显著下降。蒙特卡罗模拟与OSLD测量结果密切一致，剂量的平均相对误差为1.4%，LET的平均相对误差为3.2%。使用OSLD进行LET测定可对电离猝灭响应进行校正。
OSLD似乎是用于同时评估人体模型质子照射中剂量和LET分布的出色探测器。OSLD可以切割成几乎任何尺寸和形状，使其非常适合在模型内测量，以探测预定义感兴趣区域内的辐射质量和剂量。尽管我们展示了在自适应质子治疗工作流程的实验验证中获得的结果，但相同的方法可以推广并用于各种需要准确评估点剂量和/或平均LET的临床创新和工作流程开发。
