Witek Matthew, Vahknenko Yelena, Siglin Joshua, Harrison Amy, Xiao Ying, Lui Haison, Andrews David, Shi Wenyin
Department of Radiation Oncology, Thomas Jefferson University Hospital, Philadelphia, USA.
Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, USA.
Int J Med Phys Clin Eng Radiat Oncol. 2014 Aug;3(3):176-182. doi: 10.4236/ijmpcero.2014.33023.
We evaluated the feasibility of combined hippocampal- and scalp-sparing intensity-modulated radiotherapy (IMRT) plans. This study included 7 patients who received conventional palliative whole brain radiation treatment (WBRT) for brain metastasis. The brain, hippocampus, and scalp were contoured and replanned with intensity modulated radiation therapy. The prescription dose was 30 Gray (Gy) in 10 fractions with hippocampus and normal structure constraints per the Radiation Therapy Oncology Group (RTOG) 0933 protocol. Further planning was done to minimize the scalp dose while maintaining the dose constraints for the hippocampus. Dose volume histograms were obtained from conventional opposed lateral fields, IMRT and compared. Planning target volume (PTV) coverage for all plans fell within the RTOG 0933 critical structure acceptable variation category. When compared to traditional opposed lateral fields, the IMRT plan with combined hippocampal- and scalp-sparing constraints was able to significantly reduce the max and mean scalp dose as well as the percentage of scalp receiving 10 and 20 Gy by 46% and 35%, respectively, while maintaining acceptable RTOG 0933 hippocampal dose variations. We conclude that acceptable PTV coverage and sparing of the scalp and hippocampus can be accomplished using a 9-field non-coplanar IMRT plan. Prospective study is warranted to understand the impact on radiation induced alopecia.
我们评估了海马区和头皮保护调强放射治疗（IMRT）联合计划的可行性。本研究纳入了7例因脑转移接受传统姑息性全脑放射治疗（WBRT）的患者。对脑、海马区和头皮进行轮廓勾画，并采用调强放射治疗重新规划。根据放射肿瘤学组（RTOG）0933方案，处方剂量为30格雷（Gy），分10次给予，同时对海马区和正常结构进行限制。进一步规划以在维持海马区剂量限制的同时尽量减少头皮剂量。从传统对侧野、IMRT获取剂量体积直方图并进行比较。所有计划的计划靶区（PTV）覆盖均在RTOG 0933关键结构可接受变异范围内。与传统对侧野相比，具有海马区和头皮保护联合限制的IMRT计划能够分别显著降低头皮的最大剂量和平均剂量以及接受10 Gy和20 Gy的头皮百分比，降幅分别为46%和35%，同时维持RTOG 0933可接受的海马区剂量变异。我们得出结论，使用9野非共面IMRT计划可以实现可接受的PTV覆盖以及对头皮和海马区的保护。有必要进行前瞻性研究以了解其对放射性脱发的影响。
