CT引导徒手腔内联合插植自适应后装与传统A点后装治疗宫颈癌剂量比较

目的 探讨CT引导徒手腔内联合插植实现影像引导自适应后装(IGABT)相较于传统A点二维后装(CP)剂量学优势,明确其在宫颈癌治疗中的价值。方法 选取在中山大学肿瘤医院行全量放疗的宫颈癌患者 26例,每例患者行4次后装治疗。治疗时先徒手置入宫腔管及2根插植针,后增加插植针数量并调整方向、深度,分别行CT扫描获得2套图像。勾画高危临床靶区(HRCTV),A点和危及器官(直肠、膀胱及乙状结肠)。在2套图像上分别行CP和IGABT计划设计,并配对t检验、Wilcoxon检验两者剂量参数差异。结果 以CP计划的覆盖指数(CI)进行分组,A组(CI≥0.90)包含20个CP和对应IGABT计划,B组(CI<0.90)包含84个CP和对应IGABT计划。A组的HRCTV体积及肿瘤直径明显小于B组(46.7cm³∶62.1cm³,P<0.001及3.1cm∶4.4cm,P<0.0001)。IGABT显著提高所有及B组D90%及覆盖指数,降低膀胱剂量,减少A组乙状结肠剂量,并改善剂量适形度及均匀性。结论 IGABT能提高靶区覆盖、剂量适形度和均匀性,保护危及器官,且对肿瘤较大的患者仍有优势。

Dosimetric comparison between CT-guided free-hand intracavity/interstitial adaptive brachytherapy and conventional point-A brachytherapy in the treatment of cervical cancer

Objective To analyze the dosimetric differences between CT-guided free-hand intracavity/interstitial brachytherapy[image-guided adaptive brachytherapy (IGABT)] and conventional point-A plan (CP) in the treatment of cervical cancer. Methods Twenty-six cervical cancer patients who received four cycles of IGABT in Sun Yat-sen University Cancer Center were enrolled in this study. Two sets of CT images were obtained before and after applicator adjustment to aid in the design of CP and IGABT plans. The high-risk clinical target volume (HRCTV), point A, and organs at risk (bladder, rectum, and sigmoid colon) were defined on CT images. CP and IGABT plans were designed on CT images. Parameter differences between CP and IGABT plans were analyzed with paired t-test and Wilcoxon test. Results According to the coverage index (CI) of CP, plans were divided into two groups:in group A (CI≥0.90), 20 CP and corresponding IGABT plans were included, and 84 CP and corresponding IGABT plans in group B (CI<0.90). The mean volume of HRCTV and mean tumor diameter in group A were significantly smaller than those in group B (46.7 cm³ vs. 62.1 cm³, P<0.001 and 3.1 cm vs. 4.4 cm, P<0.001). Compared with CP, IGABT significantly improved the value of D90% in all plans and group B, whereas lowered the bladder dose. IGABT also reduced the dose of sigmoid colon in group A. IGABT significantly improved conformal index and dose homogeneity index. Conclusions IGABT can significantly improve the target coverage, conformal index and dose homogeneity index, protect organs at risk. Compared with CP, IGABT has advantages in the treatment of patients with bulky tumor.