Knudtsen Ingerid Skjei, Svestad Jørund Graadal, Skaug Sande Erlend Peter, Rekstad Bernt Louni, Rødal Jan, van Elmpt Wouter, Öllers Michel, Hole Eli Olaug, Malinen Eirik
Department of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo, Norway. Department of Medical Physics, Oslo University Hospital, P.O. Box 4953 Nydalen, N-0424 Oslo, Norway.
Phys Med Biol. 2016 Mar 21;61(6):2243-54. doi: 10.1088/0031-9155/61/6/2243. Epub 2016 Feb 25.
Biologic image guided radiotherapy (RT) with escalated doses to tumour sub volumes challenges today's RT dose planning and delivery systems. In this phantom study, we verify the capability of a clinical dose planning and delivery system to deliver an 18F-FDG-PET based dose painted treatment plan to a lung tumour. Furthermore, we estimate the uncertainties of the dose painted treatment compared to conventional RT plans. An anthropomorphic thorax phantom of polystyrene and polyurethane was constructed based on CT images of a lung cancer patient. 101 EPR/alanine dosimeters were placed in separate cavities within the phantom. IMRT and VMAT plans were generated in Eclipse (version 10.0, Analytical Anisotropic Algorithm version 10.2.28, Varian Medical Systems, Inc.) for 6 and 15 MV photons, based on 18F-FDG-PET/CT images of the patient. A boost dose of 3.8 Gy/fraction was given to the 18F-FDG-avid region (biological planning volume; BTV), whereas 3.1 Gy/fraction was planned to the planning target volume (PTV, excluding the BTV). For the homogenous plans, 3.2 Gy/fraction was given to the PTV. Irradiation of the phantom was carried out at a Varian Trilogy linear accelerator (Varian Medical Systems, Inc.). Uncertainties involved in treatment planning and delivery were estimated from portal dosimetry gamma evaluation. Measured and calculated doses were compared by Bland-Altmann analysis. For all treatment plans, all dose-volume objectives could be achieved in the treatment planning system. The mean absolute differences between calculated and measured doses were small (<0.1 Gy) for BTV, PTV-BTV, lung and soft tissue. The estimated uncertainty of the planned doses was less than 3% for all plans, whereas the estimated uncertainty in the measured doses was less 2.3%. Our results show that planning and delivery of dose escalated lung cancer treatment on a clinical dose planning and delivery system has high dosimetric accuracy. The uncertainties associated with the dose escalated treatment plans are comparable to the conventional plans.
对肿瘤亚体积进行剂量递增的生物图像引导放射治疗（RT）对当今的RT剂量规划和输送系统提出了挑战。在这项体模研究中，我们验证了一种临床剂量规划和输送系统向肺肿瘤输送基于18F-FDG-PET的剂量描绘治疗计划的能力。此外，我们估计了与传统RT计划相比剂量描绘治疗的不确定性。基于一名肺癌患者的CT图像构建了一个由聚苯乙烯和聚氨酯制成的人体胸部体模。101个电子顺磁共振/丙氨酸剂量计被放置在体模内的单独腔室中。基于患者的18F-FDG-PET/CT图像，在Eclipse（版本10.0，分析各向异性算法版本10.2.28，瓦里安医疗系统公司）中为6和15MV光子生成调强放疗（IMRT）和容积调强弧形治疗（VMAT）计划。对18F-FDG摄取区域（生物规划体积；BTV）给予3.8Gy/分次的增敏剂量，而对计划靶体积（PTV，不包括BTV）计划给予3.1Gy/分次。对于均匀计划，对PTV给予3.2Gy/分次。在瓦里安Trilogy直线加速器（瓦里安医疗系统公司）上对体模进行照射。通过射野剂量学伽马评估估计治疗计划和输送中涉及的不确定性。通过Bland-Altmann分析比较测量剂量和计算剂量。对于所有治疗计划，在治疗计划系统中所有剂量体积目标均可实现。BTV、PTV-BTV、肺和软组织的计算剂量与测量剂量之间的平均绝对差异较小（<0.1Gy）。所有计划的计划剂量估计不确定性小于3%，而测量剂量的估计不确定性小于2.3%。我们的结果表明，在临床剂量规划和输送系统上进行剂量递增的肺癌治疗的规划和输送具有高剂量学准确性。与剂量递增治疗计划相关的不确定性与传统计划相当。
