宫颈癌三维后装治疗插植针路径优化的可行性研究

目的 比较宫颈癌腔内结合插植后装治疗(IC/IS BT)时徒手方式插针计划与虚拟优化插针计划的剂量学差异,探讨现有插植后装计划的改善空间。方法 回顾性分析18例宫颈癌高剂量率放疗计划,利用Nucletron Oncentra三维近距离治疗计划系统在已实施的徒手方式插植后装治疗计划(Treatment-Plan)的基础上,再为每例患者设计一个虚拟优化插植后装治疗计划(Optimized-Plan)。运用剂量体积直方图评估两种计划的高危临床靶区剂量分布、危及器官受量及计划执行效率。结果 两种计划相比较,Optimized-Plan显示出更适形的靶区覆盖和更均匀的剂量分布(P=0.000、0.008)。膀胱、直肠、乙状结肠和小肠的D0.01 cm³、D1 cm³、D2 cm³和D5 cm³差异均有统计学意义(P<0.05),Optimized-Plan可以降低危及器官受量,膀胱、直肠、乙状结肠、小肠D2 cm³分别减小60.41、36.43、27.53、12.43 cGy。计划执行时间上,Treatment-Plan为(857.92±243.39) s,Optimized-Plan为(804.53±239.13) s,平均缩短53.39s (P<0.001)。结论 虚拟优化插针计划比徒手方式插针计划显示出更适形的靶区覆盖和更均匀的剂量分布,同时各危及器官受量都有不同程度降低,计划执行时间缩短。

Study of the feasibility of needle path optimization in 3D brachytherapy for cervical cancer

Objective To compare the dosimetric differences between free-hand method and virtually optimized method for implanting needles in intracavitary and interstitial combined brachytherapy (IC/IS BT) of cervical cancer, and to explore the improvement space of the existing interstitial brahcytherapy plan. Methods High-dose-rate cervical cancer IC/IS BT plans (short for Treatment-Plan) of 18 cases were retrospectively analyzed. For each treatment plan, Nucletron Oncentra 3D brachytherapy planning system was utilized to redesign the virtually optimized insertion method IC/IS BT plan (short for Optimized-Plan). Dose volume histogram was adopted to evaluate the dose distribution in high-risk clinical target areas and exposure dose to organ at risk (OAR). The plan execution efficiency between two plans was also assessed. Results Comparing these two plans, the differences in conformity and uniformity of dose distribution of the target area were statistically significant (P=0.000,0.008). The differences of D0.01 cm³, D1 cm³, D2 cm³ and D5 cm³ in bladder, rectum, sigmoid and small bowel were all statistically significant (all P<0.05). Optimized-Plan could reduce the D2 cm³ of bladder, rectum, sigmoid and small bowel by 60.41, 36.43, 27.53 and 12.43 cGy, respectively. The execution time for the Treatment-Plan and Optimized-Plan were (857.92±243.39) s and (804.53±239.13) s with statistical significance (P<0.001). Conclusions Compared with the free-hand method, virtually optimized method yields more conformable coverage of the target area and more uniform dose distribution. At the same time, the doses of each OAR are reduced to different degrees and the execution time of the plan is also shortened.