Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.
Med Phys. 2024 Mar;51(3):2200-2209. doi: 10.1002/mp.16796. Epub 2023 Nov 6.
The continued development of new radiotherapy techniques requires dosimetry systems that satisfy increasingly rigorous requirements, such as high sensitivity, wide dose range, and high spatial resolution. An emerging requirement is the ability to read out doses in three dimensions (3D) with high precision and spatial resolution. A few dosimetry systems with 3D capabilities are available, but their application in a clinical workflow is limited for various reasons, primarily originating from their chemical nature. The search for a 3D dosimetry system with potential for clinical implementation is thus ongoing.
To demonstrate the capabilities of a novel optically-stimulated-luminescence (OSL)-based 3D dosimetry system capable of measuring radiation doses in clinically relevant volumes.
A laser-based readout system was used to measure dose distributions delivered by both photons and protons, utilizing the OSL from a mm YSO:Ce crystal. A homogeneous treatment plan consisting of two opposing photon fields was used to establish an inhomogeneity correction map of the crystal response and demonstrated the accuracy and precision of the system. The crystal was additionally irradiated with a photon treatment plan consisting of three overlapping mm fields delivered from different angles, and a proton treatment plan consisting of four pencil beams with energies 90 MeV ( ), 115 MeV, and 140 MeV. The system abilities were quantified by comparing the 3D-resolved measurements to Monte Carlo simulations.
The dose map reproducibility of the system was found to be within 2% including both statistical and systematic errors. The measurements yielded integrated doses from a volume of mm with voxel volumes of just mm . An excellent agreement between the 3D-resolved measurements and the simulations was found for both photon- and proton-irradiation.
The capabilities of the devised system for measuring clinically relevant fields of photons and proton pencil beams within a clinically relevant volume were demonstrated. The system poses as a promising candidate for clinical applications, and enables future research in the field of OSL-based tissue-equivalent 3D dosimetry.
新放疗技术的不断发展需要满足越来越严格要求的剂量测量系统，例如高灵敏度、宽剂量范围和高空间分辨率。一个新兴的要求是能够以高精度和空间分辨率读取三维（3D）剂量。有一些具有 3D 能力的剂量测量系统，但由于各种原因，其在临床工作流程中的应用受到限制，主要源于其化学性质。因此，正在寻找一种具有临床应用潜力的 3D 剂量测量系统。
展示一种新型基于光激励发光（OSL）的 3D 剂量测量系统的能力，该系统能够测量临床相关体积内的辐射剂量。
使用基于激光的读出系统，利用 mm YSO:Ce 晶体的 OSL，测量光子和质子传输的剂量分布。使用两个相反的光子场组成的均匀治疗计划来建立晶体响应的不均匀性校正图，并演示系统的准确性和精度。此外，还使用由来自不同角度的三个重叠 mm 射野组成的光子治疗计划和由四个能量为 90 MeV（ ）、115 MeV 和 140 MeV 的铅笔束组成的质子治疗计划对晶体进行辐照。通过将 3D 分辨测量值与蒙特卡罗模拟进行比较，来量化系统的能力。
系统的剂量图重现性被发现包括统计和系统误差在内均在 2%以内。该测量方法能够测量 mm 体积的积分剂量，体素体积仅为 mm 。在光子和质子辐照下，3D 分辨测量值与模拟值之间存在极好的一致性。
所设计的系统在临床相关体积内测量光子和质子铅笔束的临床相关场的能力得到了证明。该系统有望成为临床应用的候选者，并为基于 OSL 的组织等效 3D 剂量测量领域的未来研究提供支持。
