Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Radiother Oncol. 2010 Feb;94(2):181-7. doi: 10.1016/j.radonc.2009.12.020. Epub 2010 Jan 19.
To demonstrate the feasibility of back-projection portal dosimetry for accurate 3D dosimetric verification of volumetric-modulated arc therapy (VMAT), pre-treatment as well as in vivo.
Several modifications to our existing approach were implemented to make the method applicable to VMAT: (i) gantry angle-resolved data acquisition, (ii) calculation of the patient transmission, (iii) compensation for detector 'flex' and (iv) 3D dose reconstruction and evaluation.
Planned and EPID-(Electronic Portal Image Detector)-reconstructed dose distributions show good agreement for pre-treatment verification of two prostate, a stereotactic lung and a head-and-neck VMAT plan and for in vivo verification of VMAT treatments of prostate and lung cancer. Averaged over pre-treatment verifications, planned and measured isocentre dose ratios were -1.2% (range [-4.7%,1.8%]). 3D gamma analysis (3% maximum dose, 3mm) revealed mean gamma gamma(mean)=0.37 [0.34,0.39], maximum 1% gamma gamma(1%)=0.72 [0.66,0.81] and percentage of points with gamma1 P(gamma)(1)=99% [97%,100%]. For in vivo verification, the average isocentre dose ratio was -1.2% [-0.8%,-1.7%], gamma(mean)=0.52 [0.40,0.64], gamma(1%)=0.92 [0.76,1.08] and P(gamma)(1)=96% [93%,100%].
Our portal dosimetry method was successfully adapted for verification of VMAT treatments, pre-treatment as well as in vivo.
为了展示逆向投影门控剂量学在体模和治疗前阶段对容积调强弧形治疗（VMAT）的精确 3D 剂量验证的可行性。
对我们现有的方法进行了几项修改，使其适用于 VMAT：（i）采集机架角度分辨数据，（ii）计算患者透射，（iii）补偿探测器“弯曲”，以及（iv）3D 剂量重建和评估。
对两个前列腺、一个立体定向肺和一个头颈部 VMAT 计划的治疗前验证以及前列腺和肺癌 VMAT 治疗的在体验证，计划和 EPID（电子射野影像系统）重建剂量分布显示出良好的一致性。在治疗前验证中，平均计划和测量等中心剂量比为-1.2%（范围为[-4.7%，1.8%]）。3D 伽马分析（3%最大剂量，3mm）显示平均γγ（mean）=0.37 [0.34，0.39]，最大 1%γγ（1%）=0.72 [0.66，0.81]和 99%[97%，100%]点的γ1 P（γ）（1）。对于在体验证，平均等中心剂量比为-1.2%[-0.8%，-1.7%]，γ（mean）=0.52 [0.40，0.64]，γ（1%）=0.92 [0.76，1.08]和 P（γ）（1）=96%[93%，100%]。
我们的门控剂量方法成功地适应了 VMAT 治疗的验证，包括治疗前和在体阶段。
