Dimitriadis Alexis, Tsang Yatman, Thomas Russell A S, Palmer Antony L, Eaton David, Lee Jonathan, Patel Rushil, Silvestre Patallo Ileana, Gouldstone Clare, Snaith Julia A D, Kirkby Karen J, Nisbet Andrew, Clark Catharine H
Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK; Radiation Dosimetry Group, National Physical Laboratory, Teddington, UK; Department of Medical Physics, Royal Surrey County Hospital NHS Foundation Trust, Guildford, UK.
Radiotherapy Trials Quality Assurance Group, Mount Vernon Hospital, London, UK.
Radiother Oncol. 2020 Jun;147:153-161. doi: 10.1016/j.radonc.2020.05.024. Epub 2020 May 20.
Assessment of dosimetric accuracy of radiosurgery on different treatment platforms.
Thirty-three single fraction treatment plans were assessed at thirty centres using an anthropomorphic head phantom with target and brainstem structures. The target being a single irregular shaped target, ~8 cc, 10 mm from the brainstem. The phantom was "immobilised", scanned, planned and treated following the local protocols. EBT-XD films and alanine pellets were used to measure absolute dose, inside both the target and the brainstem, and compared with TPS predicted dose distributions.
PTV alanine measurements from gantry-based linacs showed a median percentage difference to the TPS of 0.65%. Cyberknife (CK) had the highest median difference of 2.3% in comparison to the other platforms. GammaKnife (GK) showed the smallest median of 0.3%. Similar trends were observed in the OAR with alanine measurements showing median percentage differences of1.1%, 2.0% and 0.4%, for gantry-based linacs, CK and GK respectively. All platforms showed comparable gamma passing rates between axial and sagittal films.
This comparison has highlighted the dosimetric variation between measured and TPS calculated dose for each delivery platform. The results suggest that clinically acceptable agreement with the predicted dose distributions is achievable by all treatment delivery systems.
评估不同治疗平台上放射外科手术的剂量准确性。
在30个中心使用带有靶区和脑干结构的人体头部模型对33个单次分割治疗计划进行评估。靶区为单个不规则形状的靶区，体积约8立方厘米，距脑干10毫米。按照当地方案对模型进行“固定”、扫描、计划和治疗。使用EBT-XD胶片和丙氨酸剂量计测量靶区和脑干内的绝对剂量，并与治疗计划系统（TPS）预测的剂量分布进行比较。
基于龙门式直线加速器的PTV丙氨酸测量值与TPS的中位百分比差异为0.65%。与其他平台相比，射波刀（CK）的中位差异最高，为2.3%。伽玛刀（GK）的中位差异最小，为0.3%。在危及器官（OAR）中也观察到类似趋势，丙氨酸测量显示基于龙门式直线加速器、CK和GK的中位百分比差异分别为1.1%、2.0%和0.4%。所有平台在轴向和矢状面胶片之间显示出相当的伽马通过率。
本次比较突出了每个输送平台测量剂量与TPS计算剂量之间的剂量差异。结果表明，所有治疗输送系统都能在临床上实现与预测剂量分布的可接受一致性。
