Biological effects of passive scattering and spot scanning proton beams at the distal end of the spread-out Bragg peak in single cells and multicell spheroids
Biological effects of passive scattering and spot scanning proton beams at the distal end of the spread-out Bragg peak in single cells and multicell spheroids
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DOI：
10.1080/09553002.2021.1889704
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发表时间：
2021-02-15
影响因子：
2.6
通讯作者：
Shibamoto, Yuta
中科院分区：
文献类型：
--
作者：
Nomura, Kento;Iwata, Hiromitsu;Shibamoto, Yuta
目的
本研究利用单细胞和多细胞球体研究了在扩展布拉格峰（SOBP）远端区域点扫描和被动散射质子治疗的生物学效应。
材料与方法
使用Geant4蒙特卡罗模拟计算被动散射束和点扫描束中的线性能量传递（LET）值。通过将在6Gy和15Gy照射下存活的分数分别代入剂量 - 存活曲线并读取相应剂量，利用EMT6单细胞和0.6mm的V79球体研究了在SOBP远端区域不同点的两种束流选择的生物剂量。
结果
在SOBP的入口区域，两种束流选择的LET值相似，在SOBP的远端区域LET值增加，其中点扫描束的LET值高于被动散射束。在单细胞和球体中类似地观察到在远端区域生物学效应的增加；在远端后2 - 10mm处，被动散射束和点扫描束的生物剂量分别比物理剂量高4.5 - 57%和5.7 - 86%，且点扫描束的生物剂量高于被动散射束（p < 0.05）。
结论
在单细胞和球体中，质子照射在SOBP远端的效应比根据测量的物理剂量所预期的更强，并且与LET值的增加相关。
PurposeThe present study investigated the biological effects of spot scanning and passive scattering proton therapies at the distal end region of the spread-out Bragg peak (SOBP) using single cell and multicell spheroids.Materials and methodsThe Geant4 Monte Carlo simulation was used to calculate linear energy transfer (LET) values in passive scattering and spot scanning beams. The biological doses of the two beam options at various points of the distal end region of SOBP were investigated using EMT6 single cells and 0.6-mm V79 spheroids irradiated with 6 and 15 Gy, respectively, by inserting the fractions surviving these doses onto dose-survival curves and reading the corresponding dose.ResultsLET values in the entrance region of SOBP were similar between the two beam options and increased at the distal end region of SOBP, where the LET value of spot scanning beams was higher than that of passive scattering beams. Increases in biological effects at the distal end region were similarly observed in single cells and spheroids; biological doses at 2-10 mm behind the distal end were 4.5-57% and 5.7-86% higher than physical doses in passive scattering and spot scanning beams, respectively, with the biological doses of spot scanning beams being higher than those of passive scattering beams (p < .05).ConclusionsIn single cells and spheroids, the effects of proton irradiation were stronger than expected from measured physical doses at the distal end of SOBP and were correlated with LET increases.