Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, QST, Japan.
Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.
Phys Med Biol. 2021 Feb 9;66(4):045017. doi: 10.1088/1361-6560/abd66f.
In this study, the survival fraction (SF) and relative biological effectiveness (RBE) of pancreatic cancer cells exposed to spread-out Bragg peak helium, carbon, oxygen, and neon ion beams are estimated from the measured microdosimetric spectra using a microdosimeter and the application of the microdosimetric kinetic (MK) model. To measure the microdosimetric spectra, a 3D mushroom silicon-on-insulator microdosimeter connected to low noise readout electronics (MicroPlus probe) was used. The parameters of the MK model were determined for pancreatic cancer cells such that the calculated SFs reproduced previously reported in vitro SF data. For a cuboid target of 10 × 10 × 6 cm, treatment plans of helium, carbon, oxygen, and neon ion beams were designed using in-house treatment planning software (TPS) to achieve a 10% SF of pancreatic cancer cells throughout the target. The physical doses and microdosimetric spectra of the planned fields were measured at different depths in polymethyl methacrylate phantoms. The biological effects, such as SF, RBE, and RBE-weighted dose at different depths along the fields were predicted from the measurements. The predicted SFs at the target region were generally in good agreement with the planned SF from the TPS in most cases.
在这项研究中，使用微剂量计和微剂量动力学 (MK) 模型，从测量的微剂量谱估计暴露于扩展布拉格峰氦、碳、氧和氖离子束的胰腺癌细胞的存活分数 (SF) 和相对生物效应 (RBE)。为了测量微剂量谱，使用了连接到低噪声读出电子设备（MicroPlus 探头）的 3D 蘑菇硅绝缘体微剂量计。为胰腺癌细胞确定了 MK 模型的参数，使得计算出的 SF 再现了先前报道的体外 SF 数据。对于 10×10×6 厘米的长方体靶标，使用内部治疗计划软件 (TPS) 设计了氦、碳、氧和氖离子束的治疗计划，以在整个靶标中实现 10% 的胰腺癌细胞 SF。在聚甲基丙烯酸甲酯体模的不同深度测量计划场的物理剂量和微剂量谱。从测量结果预测了不同深度的生物学效应，如 SF、RBE 和 RBE 加权剂量。在大多数情况下，目标区域的预测 SF 与 TPS 计划的 SF 大致吻合。
