Department of Radiation Oncology (MAASTRO), Maastricht University Medical Centre, The Netherlands.
Radiother Oncol. 2010 Feb;94(2):188-94. doi: 10.1016/j.radonc.2009.12.024. Epub 2010 Jan 18.
To implement a 3D dose verification procedure, based on in-room cone-beam CT imaging and portal dosimetry, for lung cancer patients treated with stereotactic body radiotherapy (SBRT).
MV cone-beam CT scans were made for patient positioning and calibrated for dose calculation purposes. Prior to treatment, the treatment fields were captured using a calibrated electronic portal imaging device (EPID). A Monte Carlo dose reconstruction model was used to estimate the 3D dose delivered to the patient inside the cone-beam CT images. The planned and delivered dose distributions were compared for 4 patients and 10 treatment fractions using dose-volume histograms and gamma analysis.
The gamma analysis showed a good agreement between the planned and delivered dose distributions for patients without changes in anatomy. The delivered mean dose per fraction inside the target volume deviated on average 1.1+/-1.4% from the planned dose. For the critical organs, only minor differences were observed between the reconstructed and planned dose.
A method was presented that allows verification of the dose delivered in 3D for lung cancer patients treated with SBRT. The procedure is independent of the treatment planning system and uses in-room MV cone-beam CT imaging and portal dosimetry.
基于术中锥形束 CT 成像和射野影像装置剂量学，为接受立体定向体部放疗（SBRT）的肺癌患者实施 3D 剂量验证程序。
对患者进行 MV 锥形束 CT 扫描以进行定位，并进行剂量计算校准。在治疗前，使用经过校准的电子射野影像装置（EPID）采集治疗野。使用蒙特卡罗剂量重建模型来估算锥形束 CT 图像中患者内部的 3D 剂量分布。使用剂量-体积直方图和伽马分析，对 4 名患者和 10 个治疗分次的计划剂量分布和实际剂量分布进行了比较。
对于解剖结构无变化的患者，伽马分析显示计划剂量分布与实际剂量分布具有良好的一致性。靶区内每个分次的实际平均剂量比计划剂量平均偏差 1.1+/-1.4%。对于关键器官，重建剂量与计划剂量之间仅观察到较小的差异。
本文提出了一种可用于验证接受 SBRT 的肺癌患者 3D 剂量分布的方法。该方法不依赖于治疗计划系统，而是使用术中 MV 锥形束 CT 成像和射野影像装置剂量学。
