Wambersie A, Hendry J H, Andreo P, DeLuca P M, Gahbauer R, Menzel H, Whitmore G
International Commission on Radiation Units and Measurements, Bethesda, Maryland, USA.
Radiat Prot Dosimetry. 2006;122(1-4):463-70. doi: 10.1093/rpd/ncl447. Epub 2007 Jan 17.
This paper summarises the conclusions of a working group established jointly by the International Atomic Energy Agency (IAEA) and the International Commission on Radiation Units and Measurements (ICRU) to address some of the relative biological effectiveness (RBE) issues encountered in ion-beam therapy. Special emphasis is put on the selection and definition of the involved quantities and units. The isoeffective dose, as introduced here for radiation therapy applications, is the dose that delivered under reference conditions would produce the same clinical effects as the actual treatment in a given system, all other conditions being identical. It is expressed in Gy. The reference treatment conditions are: photon irradiation, 2 Gy per fraction, 5 daily fractions a week. The isoeffective dose D(IsoE) is the product of the physical quantity absorbed dose D and a weighting factor W(IsoE). W(IsoE) is an inclusive weighting factor that takes into account all factors that could influence the clinical effects like dose per fraction, overall time, radiation quality (RQ), biological system and effects. The numerical value of W(IsoE) is selected by the radiation-oncology team for a given patient (or treatment protocol). It is part of the treatment prescription. Evaluation of the influence of RQ on W(IsoE) raises complex problems because of the clinically significant RBE variations with biological effect (late vs. early) and position in depth in the tissues which is a problem specific to ion-beam therapy. Comparison of the isoeffective dose with the equivalent dose frequently used in proton- and ion-beam therapy is discussed.
本文总结了国际原子能机构（IAEA）和国际辐射单位与测量委员会（ICRU）联合成立的一个工作组的结论，该工作组旨在解决离子束治疗中遇到的一些相对生物效应（RBE）问题。特别强调了相关量和单位的选择与定义。本文引入的用于放射治疗应用的等效剂量，是指在参考条件下给予的剂量，在给定系统中会产生与实际治疗相同的临床效果，其他所有条件均相同。它以戈瑞（Gy）表示。参考治疗条件为：光子照射，每次分割剂量2 Gy，每周5次分割。等效剂量D（IsoE）是物理量吸收剂量D与加权因子W（IsoE）的乘积。W（IsoE）是一个综合加权因子，它考虑了所有可能影响临床效果的因素，如每次分割剂量、总治疗时间、辐射质量（RQ）、生物系统和效应。W（IsoE）的数值由放射肿瘤学团队为特定患者（或治疗方案）选定。它是治疗处方的一部分。由于RQ对W（IsoE）的影响评估会引发复杂问题，因为临床上RBE会因生物效应（晚期与早期）以及在组织中的深度位置而有显著变化，这是离子束治疗特有的问题。本文还讨论了等效剂量与质子和离子束治疗中常用的当量剂量的比较。
