三维适形放疗治疗复发子宫颈癌的剂量学研究

目的 比较常规放疗和三维适形放疗(3DCRT)治疗复发子宫颈癌靶区(PTV)和危及器官(OAR)的剂量分布,为3DCRT在复发子宫颈癌中的应用提供依据.方法 选取2007年5月至8月间就诊于山西省肿瘤医院的13例复发的子宫颈癌患者,CT模拟定位后,影像资料输入拓能(Topslane)三维治疗计划系统,由同一物理师对每一患者分别进行传统前后对穿野和五野三维适形计划设计,处方剂量均为50 Gy,比较二者PTV和OAR的剂量分布.结果 在相同的处方剂量(50 Gy),普通放疗(CRT)(AP/PA)和3DCRT的OAR(直肠、膀胱、小肠)最大受照剂量间差异无统计学意义(P>0.05),而二者PTV的最大受照剂量间差异有统计学意义(P<0.001),比较PTV的平均剂量则无统计学意义(P>0.05).表明CRT(AP/PA)和3DCRT二者有着同样的PTV覆盖.经比较PTV的均匀性,在CRT(AP/PA)和3DCRT间差异有统计学意义(P<0.001).比较CRT(AP/PA)和3DCRT的各OAR高剂量区(>40 Gv)的受照体积(V40)后,二者各OAR的V40间差异有统计学意义(P<0.01),3DCRT的V40在直肠、膀胱、小肠比CRT(AP/PA)分别平均减少53.31 ml(90.69%)、124.00 ml(79.47%)、655.16 ml(92.22%).结论 3DCRT治疗的PTV剂量均匀性劣于CRT,而OAR的受照体积明显少于CRT,从而有望减少OAR放疗并发症发生率(NTCP).

Dosimetry study of three-dimension conformal radiation therapy(3DCRT) in treating cervical cancer recurred in pelvis

Objective To eompare the dose distribution of three-dimension conformal radiation therapy(3DCRT) and common radiation therapy (CRT) of the planning target volume(PTV) and organ at risk (OAR) in recurred cervical cancer treatment planning. Methods Thirteen patients,who had cervical cancer recurred in pelvis treated with 3DCRT in Shanxi Cancer Hospital from May to August 2007, were selected. After CT simulation, the CT images were transferred into Topslane treatment system. The same physicist designed 3DCRT plan and common radiation therapy plan for every patient,total dose 50 Gy, 90 % is dose covered PTV, then compared the dose distribution of PTV and OAR.Results At the same prescribed dose of 50Gy,there were no significant differences on OAR maximum dose between 3DCRT plans and common radiation therapy plans(P >0.05), however, there was significant differences on PTV maximum dose(P <0.01). The difference of PTV uniformity were significant between 3DCRT plans and common radiation therapy plans (P <0.001). Compared the high dose region of OAR(V40), the difference was significant (P <0.001). Between 3DCRT plans and common radiation therapy plans, they showed 53.31 ml (90.69 %), 124.00 ml (79.47 %), 655.16 m1(92.22 %) median reduction in the V40 of rectum, bladder, intestine, respectively. Conclusion At the same PTV coverage of the prescribed dose, 3DCRT plans showed worse dose uniformity, however, the radiation volume to organs at risk in 3DCRT plans were smaller than common radiation therapy plans. So patients with cervical cancer recurred in pelvis received 3DCRT may be potentially diminish the Normal Tissue Complications Probability(NTCP).