School of Physics, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
Thailand Center of Excellence in Physics, Ministry of Higher Education, Science, Research and Innovation, Bangkok, Thailand.
Int J Radiat Biol. 2023;99(3):488-498. doi: 10.1080/09553002.2022.2110318. Epub 2022 Aug 15.
In this study, we performed biological verification measurements of cell survival of a C ion irradiation plan employing a high-resolution 3D culture setup. This allowed, in particular, to access the cell inactivation in the low-dose regions close to the target area.
We established the protocol for a 3D culture setup where xrs-5 cells were grown inside a layered matrigel structure in 384-well plates. Their radiosensitivity to conventional and C ion radiation was evaluated by irradiating them either with 250 kV X-rays at GSI or with monoenergetic C beams of 110 MeV/u at MIT, and compared with those of monolayers. A treatment plan for a rectangular target was prepared using the GSI research treatment planning system TRiP98. xrs-5 cells were seeded in the matrigel-based setup and irradiated in dose fall-off regions using active scanning C ion beams. In addition, film dosimetry utilizing radiochromic EBT3 film has been performed to assess the field homogeneity downstream of 384-well V-bottom plates with or without additional agarose coating of the well plate bottom.
Dose response curves following X-ray and C ion irradiation had linear shape and showed a significant decrease in survival fraction at even moderate doses. Survival measurements in the low-dose regions of the plan for the extended target showed good agreement to the predicted survival fraction. The irradiated film profiles yielded a flat dose distribution without apparent artifacts or inhomogeneities for well plates both with and without agarose coating, confirming the suitability of the experimental setup.
We conclude that the V-bottom 384-well plates in combination with the radiation-sensitive xrs-5 cell line constitute a suitable radiobiological verification tool which can be used especially for low doses. Furthermore, the measured survival of xrs-5 cells show a good agreement with the expected survival in the low-dose out-of-field regions, both laterally and downstream of the target.
在这项研究中，我们对使用高分辨率 3D 培养装置的 C 离子辐照计划的细胞存活进行了生物学验证测量。这特别允许接近靶区的低剂量区域中的细胞失活。
我们建立了一种 3D 培养装置的方案，其中 xrs-5 细胞在 384 孔板中的分层基质胶结构中生长。通过用 GSI 的 250kV X 射线或用 MIT 的 110MeV/u 的单能 C 束照射它们，评估了它们对常规和 C 离子辐射的辐射敏感性，并与单层的辐射敏感性进行了比较。使用 GSI 研究治疗计划系统 TRiP98 制备了矩形靶的治疗计划。将 xrs-5 细胞播种在基于基质胶的装置中，并使用主动扫描 C 离子束在剂量下降区域进行照射。此外，还利用放射性染色 EBT3 胶片进行了胶片剂量测量，以评估具有或不具有孔板底部额外琼脂糖涂层的 384 孔 V 底平板下游的场均匀性。
X 射线和 C 离子照射后的剂量响应曲线呈线性形状，并且即使在中等剂量下，存活分数也显著降低。对于扩展靶的计划的低剂量区域中的存活测量与预测的存活分数吻合良好。照射的胶片轮廓显示出平坦的剂量分布，没有明显的伪影或不均匀性，无论是带有还是不带有琼脂糖涂层的孔板，都证实了实验装置的适用性。
我们得出结论，V 底 384 孔板与辐射敏感的 xrs-5 细胞系结合构成了一种合适的放射生物学验证工具，特别是对于低剂量。此外，xrs-5 细胞的测量存活与靶区横向和下游低剂量场外区域的预期存活吻合良好。
