目的 建立一个定性比较同一病人的同一“并联器官”毒副反应的数学模型,解决在评价治疗计划时比较Vx(V5、V10、V20等)和MLD的困难.方法 基于LQ模型,推导出一个“并联器官”接受照射治疗后细胞存活数目的公式,理论上它能将两个计划的照射剂量转化为两个计划中“并联器官”内各自的细胞存活数,判定细胞存活数的定性关系,即能得到两个计划的优劣.随机选择1例肺癌病人,采用ELEKTA precise 2.12系统设计两个达到临床要求的治疗计划,并用该模型对其进行比较来说明该过程;随机选取45例病人分别设计两个计划,分别计算该模型(WB模型)与LKB模型在选取计划时的结果差异,同时将其与分别单独采用Vx(V5、V10、V20等)和MLD选取计划中的结果进行对比分析.结果 采用WB模型选取计划获得了与采用LKB模型选取计划时一样的结果,无统计学差异(P＞0.05);采用WB模型选取计划与分别单独采用V5、V10、V20和MLD选取计划在统计学上无差异(P＞0.05).结论 WB模型在并联器官评价选出最优计划时是有效的,能避开比较Vx(V5,V10,V20等)和MLD方法的局限;V5,V10,V20和MLD是放射性并发症发生的重要预后因素.%Objective To develop a new bio-mathematical model named which better model (WB model), which can overcome the limitation of using Vx(V5, V20, V50.etc. ), to rank radiotoxicity of the same "paralled organ" of the same patient. Methods "Paralled organ" is consisted of FSUs (function subunits) , and each FSU is equal and respective in functional status . The previous studies shown that FSU afunction was attributed to some kind of cells damaged. Based on the linear-quadratic(LQ) model, with the consideration of parallel organ architecture, we derived a new parallel organ bio-mathematical model to calculate cell survival number for radiation dose (D) response. Then we compared cell survival number of a "parallel organ" for ranking treatment plans for the same patient. Ninety 3D plans for forty-five randomly selected chest cancer patients generated using ELEKTA precise 2.12 system, the validity of WB model was tested by LKB model which universal in clinic. SPSS 17. 0 software was used for statistical analysis. Results WB model could overcome the limitation of using Vx (V5, V20, V50, etc. ) for plan ranking. Ranking plans by WB model and LKB model respectively, there was no statistically difference between them (P = 0. 475). Ranking plans by Vx, MLD and LKB model, there was no statistically difference among V5, V10, V20 and MLD(P>0. 05). Conclusions WB model proposed for parallel organ is useful for ranking plans for the same patient. V5, V10, V20 and MLD play an important role in ranking plans.
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