Vatnitsky S M, Schulte R W, Galindo R, Meinass H J, Miller D W
Department of Radiation Medicine, Loma Linda University Medical Center, CA 92354, USA.
Phys Med Biol. 1997 Oct;42(10):1887-98. doi: 10.1088/0031-9155/42/10/003.
In this work we studied the feasibility of radiochromic film for dosimetry verification of proton Bragg peak stereotactic radiosurgery with multiple beams. High-sensitivity MD-55 radiochromic film was calibrated for proton beam irradiation and the RIT 113 system was employed for film evaluation. Simulated stereotactic radiosurgery with a special phantom arrangement for film dosimetry was performed, following the same procedure as for a patient undergoing treatment. Five-beam irradiation was developed using a 3D treatment planning system. This plan was then delivered to the phantom in a one-day experiment. Planned and measured composite dose distributions were compared. Spatial accuracy of dose delivery to a region containing a simulated critical structure was evaluated for a single portal. Radiochromic film dosimetry validated the prescribed dose delivery within +/- 5%, one standard deviation, by comparing calculated doses with measured values. The alignment of apertures and boluses, as well as the alignment of the phantom with respect to the isocentre, was confirmed. Spatial accuracy of the method would have been able to detect possible misalignments greater than +/- 2 mm. We have demonstrated how radiochromic film dosimetry can be used to measure complex dose distributions in an irradiated phantom, thus enabling us to verify planned dose delivery of proton Bragg peak stereotactic radiosurgery with multiple beams. We assume that the dosimetric agreement between planned and measured dose distributions for the reported simulations will apply to patient treatments.
在本研究中，我们探讨了使用放射变色薄膜对多束质子布拉格峰立体定向放射外科手术进行剂量验证的可行性。对高灵敏度MD - 55放射变色薄膜进行质子束照射校准，并采用RIT 113系统对薄膜进行评估。按照与患者治疗相同的程序，使用特殊的模体装置进行模拟立体定向放射外科手术的薄膜剂量测定。利用三维治疗计划系统设计五束照射方案。然后在一天的实验中将该方案应用于模体。比较计划和测量的复合剂量分布。评估单个射野向包含模拟关键结构的区域进行剂量传递的空间精度。通过将计算剂量与测量值进行比较，放射变色薄膜剂量测定法验证了规定剂量传递在±5%（一个标准差）范围内。确认了限光筒和填充物的对准情况以及模体相对于等中心的对准情况。该方法的空间精度能够检测出大于±2 mm的可能对准偏差。我们已经证明了放射变色薄膜剂量测定法如何用于测量受照模体中的复杂剂量分布，从而使我们能够验证多束质子布拉格峰立体定向放射外科手术的计划剂量传递。我们假定所报告模拟中计划和测量剂量分布之间的剂量学一致性适用于患者治疗。
