宫颈癌盆腔组织校正对放疗剂量学影响的研究

Study on the Impact of Correction or Non-correction for Pelvic Cavity Tissue on Dosimetry in Cervical Carcinoma Patients

目的比较不均匀盆腔组织校正对宫颈癌患者的肿瘤靶区、正常组织及重要器官放疗剂量分布的影响。方法选择9例经病理证实为原发性宫颈癌的患者,每例患者同时设计两组治疗计划,模拟常规放疗不校正不均匀盆腔组织计划(计划1)、三维适形放疗(3DCRT)校正不均匀盆腔组织计划(计划2)。计划1为前后左右对穿照射50 Gy,通过调节剂量权重使处方剂量与常规放疗的相同;射野大小、其他参数与常规放疗的相同,此时得到计划1的剂量分布就是常规不校正不均匀盆腔组织在患者体内的实际分布。计划2为3DCRT照射50 Gy。将计划1与计划2进行比较。结果计划2 PTV的Dmax和Dmean均较计划1高(P<0.05);计划2均匀性指数(HI)、适形度指数(CI)值均较计划1大(P<0.05);计划2膀胱、直肠、小肠、左右侧股骨头的Dmean均较计划1低(P<0.05)。结论 3DCRT校正不均匀盆腔组织更合理。

Objective To explore the impact of correction for non-uniform pelvic cavity tissue on the dose distribution of gross tumor target,normal tissue and organs at risk of patients with cervical carcinoma. Methods Night cases of cervical carcinoma were enrolled in the study. Two radiotherapy plans were designed for each case：plan of non-correction in routine radiotherapy for non-uniform pelvic cavity tissue （Plan 1 ）, plan of correction in 3-dimensional conformal radiotherapy （3DCRT） for non-uniform pelvic cavity tissue（Plan 2）. Plan 1 included 50 Gy irradiation for anterior and posterior fields, making prescription dose same as that of the routine radiotherapy by adjusting the dose weight, and the irradiation field size and other parameters same as those of the routine radiotherapy. Then the dose distribution of Plan 1 was the actual distribution in the patient＇s body at the moment. Plan 2 included 50 Gy irradiation of 3DCRT. The dose distributions of Plan 1 and Plan 2 were compared. Results Dmax and Dmean of PTV of Plan 2 were higher than those of Plan 1 （P 〈 0.05 ）. Values of homogeneity index（HI） and conformity index（CI） of Plan 2 were larger than those of Plan 1 （P 〈 0.05 ）. Dmeans of bladder, small intestine, left and right thiqhbone of Plan 2 were lower than those of Plan 1 （P 〈 0.05）. Conclusion Correction in 3DCRT is more reasonable for non-uniform pelvic cavity tissue.