非共面IMRT在宫颈癌放疗计划中保护卵巢的可行性探讨

目的:探讨非共面IMRT在宫颈癌放疗计划中保护卵巢的可行性。方法:选取17例保卵巢宫颈癌放疗病例,按统一标准分别设计两组IMRT计划:共面IMRT保卵巢组(A组)和非共面IMRT保卵巢组(B组);收集两组计划评估参数,并验证两组计划γ通过率,并进行统计学分析。结果:两组计划均满足临床要求。B组的卵巢最大受量小于A组(P<0.05)。对于计划靶区,B组计划的适形指数、均匀指数优于A组计划(P<0.05),A组D 5高于B组(P<0.05),B组D 95高于A组(P<0.05)。对于危及器官,A组在膀胱的V_(40)、直肠的D_(mean)、小肠的D max、左侧股骨头的V_(20)大于B组(P<0.05)。A组和B组在膀胱的V_(20)、V_(30)、D_(mean),直肠的V_(30)、V_(40),小肠的V_(40),右侧股骨头的V_(10)、V_(20)、V_(30),左侧股骨头的V_(10)、V_(30)和骨髓的D max上均无明显差异(P>0.05)。A组的总跳数小于B组(P<0.05);在3%/2 mm,低剂量阈值10%的标准下,A组γ通过率高于B组(P<0.05)。结论:两种计划均能实现对卵巢的保护,非共面IMRT计划表现更佳,靶区剂量分布更优,对危及器官影响更小。

Dosimetric Study of Coplanar and Non-Coplanar Intensity-Modulated Radiation Therapy Planning for Esophageal Carcinoma

Purpose: To compare the dosimetric impact of coplanar intensity modulated radiation therapy (IMRT) and non-coplanar IMRT for the esophageal carcinoma. Methods: There are forty-five esophageal carcinoma patients, fifteen of whom were cervical and upper thoracic (Group 1) and thirty were middle and lower thoracic (Group 2). Gross tumor volume (GTV), clinical target volume (CTV), and organs at risk (OAR) were contoured by the chief physician in the CMS-XiO treatment planning system. For each patient, one coplanar plan and two non-coplanar plans have been created using the same physical objective function. A detailed dose-volume histogram (DVH) comparison among three plans was then carried out in a tabulated format. Results: 1) In Group 1 patients with PTV volume less than 100cc, the mean dose and dose gradient of non-coplanar plan were much better than those in coplanar plan. 2) In Group 2 patients, the conformity index (CI) for coplanar and two non-coplanar plans were 0.69 ± 0.13, 0.41 ± 0.13, and 0.68 ± 0.15, respectively. The V5, V10, V20, and the mean dose to the lung were lower in the non-coplanar plans compared to ones in coplanar plan. However, the non-coplanar plans resulted in an increase in a dose to the heart, but the dose was still within heart toxicity tolerance. Conclusion: For Group 1 patients, the non-coplanar IMRT plan had less dose gradient and better mean dose than the coplanar IMRT plan. For Group 2 patients, the non-coplanar IMRT could the decrease dose to the lung tissue, thus lowering the probability of radiation pneumonia to esophageal cancer patients. The drawback of non-coplanar IMRT is that, even within toxicity tolerance, it could deliver a higher dose to the heart and spinal cord compared to the coplanar plan. Therefore, for patients with cardiology and neurology concern, non-coplanar IMRT should be used with caution.

转床角度对中上段食管癌非共面调强计划的影响

目的:探讨转床角度对中上段食管癌非共面调强计划的影响。方法:选择15名中上段食管癌病例先设计5野的共面调强计划,然后在共面调强计划的基础上,改变机架角330°和30°的床转角,旋转床角度从10°到90°,每10°设计一个计划。比较10组计划的靶区适形度(CI),剂量均匀性(HI),全肺的体积剂量V5、V20、V30、平均剂量(Dmean),心脏的体积剂量V30、V40、平均剂量(Dmean),脊髓的最大值(Dmax)。用SPSS软件的配对t检验方法统计靶区和危及器官的剂量学参数。结果:以折线图表示10个计划的CI和HI以及全肺、心脏和脊髓的体积剂量参数,然后对比转床角度90°和80°的非共面计划与0°的共面计划。80°计划时全肺的V5、V20为最低,分别为(45.93±7.72)%、(21.90±4.67)%,与0°计划相比,分别降低了17.92%、8.94%(P<0.05);心脏的V40、Dmean随转床角度的增加,呈逐渐上升趋势,在80°分别为V40=(10.94±6.36)%,Dmean=(2196.36±458.09)cGy,与0°计划相比,分别增加了20.62%、28.52%(P<0.05),转床角度的增加在减少全肺受照剂量的同时,也增加了心脏的受照剂量,虽然心脏受照剂量涨幅较大,但由于其基数较小,所以实际增加并不大。80°计划与90°计划相比较,全肺V20降低了4.6%(P<0.05),其余数据包括靶区适形度CI、均匀性HI、全肺V5、V30、Dmean和心脏V30、V40、脊髓Dmax,两者之间均无统计学差异(P>0.05)。脊髓最大值整体变化趋势平稳。结论:转床角度对中上食管癌计划确有明显影响,在设计食管癌非共面计划时,应充分考虑转床角度的因素,以寻求更有质量的治疗计划。

胃癌调强放疗中非共面锁野计划与共面锁野计划的剂量学比较

目的:通过比较胃癌调强放疗中共面锁野计划与非共面锁野计划的剂量学差异,为临床放疗方案的选择提供参考依据。方法:选取10例胃癌患者分别制定9野的共面锁野调强和9野非共面锁野调强的治疗计划,比较机器跳数、靶区和危及器官等参数的剂量学差异。结果:两种计划均满足临床需求。非共面计划相比锁野计划仅小肠的V20显著降低且差异具有统计学意义。对于右肾脏、肝脏、脊髓和小肠的Dmean,非共面计划略低于共面锁野计划,但参数差异均无统计学意义。结论:非共面技术相比与锁野技术在9野胃癌放疗中并未取得明显优势,从技术层面考虑,非共面技术需要转床可能会引入一些误差,所以笔者建议使用共面锁野技术。