非常规分割放疗的生物等效剂量学优势分析

An analysis of the advantage of biologically equivalent dose of unconventionally fractionatedradiotherapy

目的 采用计算生物等效剂量（BED）值的方法,对头颈部肿瘤非常规分割放疗方案进行分析,从BED值变化规律的角度来分析各种不同分割治疗方法的优劣.方法 针对Cochrane协作网在2010年公布的一项关于头颈部肿瘤非常规分割治疗的调查报告中所列举的常规分割和非常规分割治疗方案,使用L-Q模型计算BED值,分析不同治疗方案的BED值随时间的累积变化规律.结果 在总剂量统一为70 Gy的前提下,常规分割方案尤其是超分割治疗方案,可以在较短时间内集中给予肿瘤组织较大的BED值；超分割治疗可以有效地降低晚反应组织累计的BED值；分段超分割治疗方案在保证肿瘤组织获得较大BED值的同时,可以有效地降低早反应组织在治疗过程中累计的BED值.结论 使用L-Q模型计算BED值的方法对不同治疗方案进行分析,观察BED值随治疗过程的变化规律,通过数学模型评价不同的放疗分割方案,对临床选择肿瘤治疗方案起到指导作用.

Objective To analyze the advantage of altered fractionation radiotherapy by calculating the accumulative effects of daily biologically effective dose （BED） to find out the difference between conventional fractionated radiotherapy and altered fractionation radiotherapy. Methods The data in the report of hyperfractionated or accelerated radiotherapy for head and neck cancer published by Cochrane Collaboration in 2010 was analyzed. Based on the radiotherapy processes mentioned in this report, the accumulative effects of daily BED were calculated and compared in different radiotherapy processes by using linear-quadratic mode. The variation of BED in different radiotherapy processes was find out. Results In total dose of unity as the premise of 70 Gy, altered fractionation especially the hyperfractionated accelerated radiotherapy could give a higher BED to the tumor during a shorter period, hyperfractionated radiotherapy could give a lower BED to normal tissues, and hyperfractionated radiotherapy with split course could give higher BED to the tumor while lower BED to normal tissues. Conclusions The variation of BED in different radiotherapy processes can be shown clearly by linear-quadratic mode. It can be simple and shortcut through mathematical models for the evaluation of different radiotherapy plan, on clinical symptomatic selection play a guiding role in tumor therapy.