Evaluation of therapeutic gain for fractionated carbon-ion radiotherapy using the tumor growth delay and crypt survival assays
Evaluation of therapeutic gain for fractionated carbon-ion radiotherapy using the tumor growth delay and crypt survival assays
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DOI：
10.1016/j.radonc.2015.09.027
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发表时间：
2015-11-01
影响因子：
5.7
通讯作者：
Nakano, Takashi
中科院分区：
文献类型：
--
作者：
Yoshida, Yukari;Ando, Koichi;Nakano, Takashi
背景和目的：本研究的目的是评估的治疗增益的碳离子（C-离子）放射治疗使用小鼠model.Materials和方法：移植纤维肉瘤（NFSa）生长在C3 H/He小鼠和小鼠小肠用290 MeV/核子C-离子束（C-离子）照射1-12分4小时分开。结果：X射线和20 keV/μ m C离子照射后，细胞存活和肿瘤生长延迟（TGD）的等效剂量随照射次数的增加而增加，而77 keV/μ m C离子照射后的TGD则随照射次数的增加而降低。隐窝表现出更强的LET依赖性增加的α项比肿瘤，而β项依赖于LET不考虑组织。治疗增益因子，即，77 keV/μ m C-离子的肿瘤RBE与隐窝RBE之比在任何剂量下都大于1，而20 keV/μ m C-离子的肿瘤RBE与隐窝RBE之比随着每部分剂量的增加而增加。这些具体数据意味着，从治疗增益的角度来看，无论LET如何，每次使用大剂量都适合C离子放射治疗，虽然高LET辐射的小剂量/分次降低了肿瘤的总剂量。(C)2015爱思唯尔爱尔兰有限公司版权所有。
Background and purpose: The aim of the study was to evaluate the therapeutic gain of carbon ion (C-ion) radiotherapy using a mouse model.Materials and methods: Transplanted fibrosarcoma (NFSa) growing in C3H/He mice and murine small intestine were irradiated with 290 MeV/nucleon C-ion beams (C-ions) in 1-12 fractions separated by 4 h. The cell killing efficiencies of C-ions were measured using jejunum crypt survival and tumor growth delay (TGD) assays.Results: The equieffect dose for crypt survival and TGD increased with increasing number of fractions after X-rays and 20 keV/mu m C-ions, whereas TGD after 77 keV/mu m C-ions rather decreased. Crypts showed stronger LET-dependent increase in a terms than the tumor while beta terms less depended on LET irrespective of tissues. Therapeutic gain factor, i.e., a ratio of tumor RBE over crypt RBE, of 77 keV/mu m C-ions was more than unity at any doses while that of 20 keV/mu m C-ions increased with an increase in dose per fraction.Conclusions: These specific data imply that use of large dose per fraction would be suitable for C-ion radiotherapy irrespective of LET from the point of view of therapeutic gain, though small dose per fraction by high-LET radiation decreases total dose for tumor. (C) 2015 Elsevier Ireland Ltd. All rights reserved.