An assessment of PTV margin based on actual accumulated dose for prostate cancer radiotherapy.
An assessment of PTV margin based on actual accumulated dose for prostate cancer radiotherapy.
复制标题
基于前列腺癌放疗实际累积剂量的 PTV 裕度评估。
DOI：
10.1088/0031-9155/58/21/7733
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发表时间：
2013
影响因子：
3.5
通讯作者：
Chetty,IndrinJ
中科院分区：
文献类型：
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作者：
Wen,Ning;Kumarasiri,Akila;Nurushev,Teamour;Burmeister,Jay;Xing,Lei;Liu,Dezhi;Glide-Hurst,Carri;Kim,Jinkoo;Zhong,Hualiang;Movsas,Benjamin;Chetty,IndrinJ
这项工作的目的是介绍一项涉及累积剂量分布的剂量学和放射生物学评估的边缘减少研究的结果，该评估使用基于图像引导的自适应放射治疗框架进行计算。8例前列腺癌患者接受7~9、6 MV调强放射治疗(IMRT)。工作流程包括基于锥束CT(CBCT)的定位、CBCT到模拟CT图像数据集(SIM-CT)的可变形图像配准、SIM-CT上的剂量重建和剂量累积，以及使用放射生物学模型进行计划评估。对于每个患者，生成了三个IMRT计划，并对CTV应用了不同的边际。原计划的PTV边缘在前列腺/直肠前壁交界处分别为10 mm和6 mm(10/6 mm)，缩小为：(A)5/3 mm，(B)均匀3 mm。在10/6 mm、5/3 mm和3 mm的均匀边缘下，累积(实际)计划中的预测肿瘤控制概率(TCP)与原始计划相比平均下降了0.4%、0.7%和11.0%。与平均边缘为10/6、5/3和3 mm的静态计划相比，实际计划预测的2/3级直肠出血的正常组织并发症概率(NTCP)分别增加3.5%、2.8%和2.4%。对于实际剂量分布，当边缘从10/6 mm减少到5/3 mm时，预测的晚期直肠出血的NTP平均减少3.6%，当边缘减少到3 mm时，预测的晚期直肠出血的NTP平均减少1.0%。与10/6、5/3和3 mm的原始计划相比，实际计划的无并发症肿瘤控制概率(P+)平均降低了3.7%、2.4%和13.6%。在具有3 mm边际的实际计划中，Tcp和P+的显著降低来自一个异常值，其中通过基于生物模型的边际适应来个体化患者治疗计划可能产生更高质量的治疗。
The purpose of this work is to present the results of a margin reduction study involving dosimetric and radiobiologic assessment of cumulative dose distributions, computed using an image guided adaptive radiotherapy based framework. Eight prostate cancer patients, treated with 7–9, 6 MV, intensity modulated radiation therapy (IMRT) fields, were included in this study. The workflow consists of cone beam CT (CBCT) based localization, deformable image registration of the CBCT to simulation CT image datasets (SIM-CT), dose reconstruction and dose accumulation on the SIM-CT, and plan evaluation using radiobiological models. For each patient, three IMRT plans were generated with different margins applied to the CTV. The PTV margin for the original plan was 10 mm and 6 mm at the prostate/anterior rectal wall interface (10/6 mm) and was reduced to:(a) 5/3 mm, and (b) 3 mm uniformly. The average percent reductions in predicted tumor control probability (TCP) in the accumulated (actual) plans in comparison to the original plans over eight patients were 0.4%, 0.7% and 11.0% with 10/6 mm, 5/3 mm and 3 mm uniform margin respectively. The mean increase in predicted normal tissue complication probability (NTCP) for grades 2/3 rectal bleeding for the actual plans in comparison to the static plans with margins of 10/6, 5/3 and 3 mm uniformly was 3.5%, 2.8% and 2.4% respectively. For the actual dose distributions, predicted NTCP for late rectal bleeding was reduced by 3.6% on average when the margin was reduced from 10/6 mm to 5/3 mm, and further reduced by 1.0% on average when the margin was reduced to 3 mm. The average reduction in complication free tumor control probability (P+) in the actual plans in comparison to the original plans with margins of 10/6, 5/3 and 3 mm was 3.7%, 2.4% and 13.6% correspondingly. The significant reduction of TCP and P+ in the actual plan with 3 mm margin came from one outlier, where individualizing patient treatment plans through margin adaptation based on biological models, might yield higher quality treatments.