Department of Radiation Oncology, Sir Charles Gairdner Hospital, Hospital Ave, Nedlands, WA, Australia.
School of Physics, Mathematics and Computing, University of Western Australia, Crawley, WA, Australia.
Phys Eng Sci Med. 2024 Jun;47(2):455-463. doi: 10.1007/s13246-023-01374-w. Epub 2024 Jan 29.
Single plan techniques for multiple brain targets (MBT) stereotactic radiosurgery (SRS) are now routine. Patient specific quality assurance (QA) for MBT poses challenges due to the limited capabilities of existing QA tools which necessitates several plan redeliveries. This study sought to develop an SRS QA phantom that enables flexible MBT patient specific QA in a single delivery, along with complex SRS commissioning. PLA marble and PLA StoneFil materials were selected based on the literature and previous research conducted in our department. The HU numbers were investigated to determine the appropriate percentage infill for skull and soft-tissue equivalence. A Prusa MK3S printer in conjunction with the above-mentioned filaments were used to print the SRS QA phantom. Quality control (QC) was performed on the printed skull, film inserts and plugs for point dose measurements. EBT3 film and point dose measurements were performed using a CC04 ionisation chamber. QC demonstrated that the SRS QA phantom transverse, coronal and sagittal film planes were orthogonal within 0.5°. HU numbers for the skull, film inserts and plugs were 858 ± 20 and 35 ± 12 respectively. Point and EBT3 film dose measurements were within 2.5% and 3%/2 mm 95% gamma pass rate, respectively except one Gross Tumour Volume (GTV) that had a slightly lower gamma pass rate. Dose distributions to five GTVs were measured with EBT3 film in a single plan delivery on CyberKnife. In conclusion, an SRS QA phantom was designed, and 3D printed and its use for performing complex MBT patient specific QA in a single delivery was demonstrated.
现在，多脑靶区（MBT）立体定向放射外科（SRS）的单次计划技术已成为常规。由于现有 QA 工具的功能有限，MBT 的患者特定质量保证（QA）存在挑战，因此需要多次重新交付计划。本研究旨在开发一种 SRS QA 体模，使其能够在单次交付中实现灵活的 MBT 患者特定 QA，并进行复杂的 SRS 委托。根据文献和我们部门之前进行的研究，选择 PLA 大理石和 PLA StoneFil 材料。研究了 HU 数，以确定颅骨和软组织等效物的适当填充百分比。使用 Prusa MK3S 打印机和上述灯丝打印 SRS QA 体模。对颅骨、胶片插入物和插件进行点剂量测量的打印质量控制（QC）。使用 CC04 电离室进行 EBT3 胶片和点剂量测量。QC 表明，SRS QA 体模的横切面、冠状面和矢状面胶片平面在 0.5°以内正交。颅骨、胶片插入物和插件的 HU 数分别为 858±20 和 35±12。点和 EBT3 胶片剂量测量的误差分别在 2.5%和 3%/2mm 95%伽马通过率范围内，除一个 GTV 略有较低的伽马通过率。在 CyberKnife 上，使用 EBT3 胶片在单次计划交付中测量了五个 GTV 的剂量分布。总之，设计并 3D 打印了 SRS QA 体模，并展示了其在单次交付中进行复杂 MBT 患者特定 QA 的用途。
