Kato Takahiro, Fuwa Nobukazu, Murakami Masao
Department of Radiation Physics and Technology, Southern Tohoku Proton Therapy Center, Fukushima, Japan.
Department of Radiation Oncology, Ise Red Cross Hospital, Mie, Japan.
Int J Part Ther. 2020 Nov 23;7(2):42-50. doi: 10.14338/IJPT-20-00008.1. eCollection 2020 Fall.
To clarify the dose distribution characteristics for early-stage glottic cancer by comparing the dose distribution between intensity-modulated radiation therapy (IMRT) and passive scattering proton therapy (PSPT) and to examine the usefulness of PSPT for early-stage glottic cancer.
Computed tomography datasets of 8 patients with T1-2 glottic cancer who had been treated by PSPT were used to create an IMRT plan in Eclipse with 7 fields and a PSPT plan in XiO-M with 2 fields. Organs at risk (OARs) included the carotid arteries, arytenoids, inferior constrictor muscles, strap muscles, thyroid cartilage, cricoid cartilage, and spinal cord. The prescription dose was 66 GyRBE in 33 fractions to the planning target volume (PTV). All plans were optimized such that 95% of the PTV received 90% of the prescription dose considering that the skin was slightly spared.
The superiority of the PSPT was confirmed in all OARs. In the PSPT, the dose to the contralateral carotid artery and the spinal cord, which is slightly distant from the PTV, was dramatically reduced while maintaining the dose distribution uniformity of the PTV by comparison with IMRT.
PSPT for early-stage glottic cancer resulted in good target dose homogeneity and significantly spared the OARs as compared with the IMRT. PSPT is expected to be effective in reducing late effects and particularly useful for young people.
通过比较调强放射治疗（IMRT）和被动散射质子治疗（PSPT）的剂量分布，阐明早期声门癌的剂量分布特征，并检验PSPT对早期声门癌的有效性。
使用8例接受PSPT治疗的T1-2期声门癌患者的计算机断层扫描数据集，在Eclipse中创建7野IMRT计划，在XiO-M中创建2野PSPT计划。危及器官（OARs）包括颈动脉、杓状软骨、咽下缩肌、带状肌、甲状软骨、环状软骨和脊髓。处方剂量为66 GyRBE，分33次给予计划靶体积（PTV）。所有计划均进行了优化，考虑到皮肤稍有 sparing，使95%的PTV接受90%的处方剂量。
在所有OARs中均证实了PSPT的优势。与IMRT相比，在PSPT中，与PTV稍有距离的对侧颈动脉和脊髓的剂量显著降低，同时保持了PTV的剂量分布均匀性。
与IMRT相比，早期声门癌的PSPT导致了良好的靶区剂量均匀性，并显著 sparing 了OARs。PSPT有望有效减少晚期效应，对年轻人尤其有用。
