METHODS: Twenty-five patients treated in a 0.35T MR-Linac (MRidian, ViewRay) for locally-advanced pancreatic cancer were enrolled. For each patient, a nominal dose distribution was optimized on the planning MRI. Each plan was daily re-optimized if needed to match the anatomy and exported from MRIdian-TPS (ViewRay Inc.) to Eclipse-TPS (Siemens-Varian). A comparison between the two TPSs was performed considering the PTV and OARs volumes (cc), as well as dose coverages and clinical constraints.
RESULTS: From the twenty-five enrolled patients, 139 plans were included in the data comparison. The median values of percentage PTV volume variation are 10.8 % for each fraction, while percentage differences of PTV coverage have a mean value of -1.4 %. The median values of the percentage OARs volume variation are 16.0 %, 7.0 %, 10.4 % and 8.5 % for duodenum, stomach, small and large bowel, respectively. The percentage variations of the dose constraints are 41.0 %, 52.7 % and 49.8 % for duodenum, stomach and small bowel, respectively.
CONCLUSIONS: This study has demonstrated a non-negligible variation in size and dosimetric parameters when datasets are transferred between TPSs. Such variations should be clinically considered. Investigations are focused on DICOM structure algorithm employed by the TPSs during the transfer to understand the cause of such variations.
方法:25例患者接受0.35TMR-Linac(MRidian,ViewRay)用于局部晚期胰腺癌。对于每个病人来说,在计划MRI上优化了标称剂量分布.如果需要,每个计划每天重新优化以匹配解剖结构,并从MRIdian-TPS(ViewRayInc.)导出到Eclipse-TPS(Siemens-Varian)。考虑到PTV和OARs体积(cc),对两个TP进行了比较。以及剂量覆盖范围和临床限制。
结果:从25名入选患者中,139个计划纳入数据比较。每个部分的百分比PTV体积变化的中值为10.8%,而PTV覆盖率的百分比差异的平均值为-1.4%。OARs体积变化百分比的中值为16.0%,7.0%,十二指肠10.4%和8.5%,胃,小肠和大肠,分别。剂量限制的百分比变化为41.0%,十二指肠52.7%和49.8%,胃和小肠,分别。
结论:这项研究表明,当数据集在TPC之间转移时,大小和剂量学参数的变化不可忽略。这种变化应该在临床上考虑。研究的重点是在传输过程中由TPP采用的DICOM结构算法,以了解这种变化的原因。