Dose compensation based on biological effectiveness due to interruption time for photon radiation therapy
Dose compensation based on biological effectiveness due to interruption time for photon radiation therapy
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DOI：
10.1259/bjr.20200125
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发表时间：
2020-01-01
影响因子：
2.6
通讯作者：
Nagata, Yasushi
中科院分区：
文献类型：
--
作者：
Kawahara, Daisuke;Nakano, Hisashi;Nagata, Yasushi
目的：目的：评价光子辐射治疗中剂量与中断时间的关系，并提出基于生物学效应的剂量补偿方法。方法：采用蒙特卡罗模拟方法，计算了人体涎腺肿瘤的线能量分布。生物剂量（D-bio）估计使用微剂量学动力学模型。推导了有无中断时D-bio差异的物理剂量补偿因子（Delta）。中断时间（tau）变化为0.1、0.2、0.3、0.4、0.5、1、2、3、4、5、10、20、30、40、50、75和120 min。每次剂量和剂量率分别变化为2 - 8戈伊和0.1 - 24戈伊/min。当中断发生在剂量的一半时，出现1戈伊/min的最大Delta。在1戈伊/min剂量的一半时，tau >= 20 min持续2戈伊、tau = 10 min持续5戈伊和tau = 10 min持续8戈伊的Delta超过3%。剂量率引起的Delta的最大差异在2和5戈伊时在3%以内，在8戈伊时达到4.0%。剂量补偿因子是较大的每部分和高剂量率beams.Conclusion：生物学效应的损失发生由于中断。我们的建议方法可以纠正的中断时间所造成的生物学效果的意外下降。知识的进展：对于光子放射治疗，中断引起的亚致死损伤修复。本研究提出了剂量补偿方法，以减少中断的生物效应。
Objective: To evaluate the biological effectiveness of dose associated with interruption time; and propose the dose compensation method based on biological effectiveness when an interruption occurs during photon radiation therapy.Methods: The lineal energy distribution for human salivary gland tumor was calculated by Monte Carlo simulation using a photon beam. The biological dose (D-bio) was estimated using the microdosimetric kinetic model. The dose compensating factor with the physical dose for the difference of the D-bio with and without interruption (Delta) was derived. The interruption time (tau) was varied to 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 75, and 120 min. The dose per fraction and dose rate varied from 2 to 8 Gy and 0.1 to 24 Gy/min, respectively.Results: The maximum Delta with 1 Gy/min occurred when the interruption occurred at half the dose. The Delta with 1 Gy/min at half of the dose was over 3% for tau >= 20 min for 2 Gy, tau = 10 min for 5 Gy, and tau = 10 min for 8 Gy. The maximum difference of the Delta due to the dose rate was within 3% for 2 and 5 Gy, and achieving values of 4.0% for 8 Gy. The dose compensating factor was larger with a high dose per fraction and high-dose rate beams.Conclusion: A loss of biological effectiveness occurs due to interruption. Our proposal method could correct for the unexpected decrease of the biological effectiveness caused by interruption time.Advances in knowledge: For photon radiotherapy, the interruption causes the sublethal damage repair. The current study proposed the dose compensation method for the decrease of the biological effect by the interruption.