Kai Yudai, Toya Ryo, Saito Tetsuo, Kuraoka Akiko, Shimohigashi Yoshinobu, Nakaguchi Yuji, Maruyama Masato, Murakami Ryuji, Yamashita Yasuyuki, Oya Natsuo
Department of Radiological Technology, Kumamoto University Hospital, Kumamoto, Japan.
Department of Radiation Oncology, Kumamoto University Hospital, Kumamoto, Japan.
J Med Radiat Sci. 2018 Mar;65(1):39-47. doi: 10.1002/jmrs.239. Epub 2017 Jul 29.
Due to its spherical surface, scalp angiosarcoma requires careful consideration for radiation therapy planning and dose delivery. Herein, we investigated whether volumetric modulated arc therapy (VMAT) is superior to intensity modulated radiation therapy (IMRT) in terms of the plan quality and delivery time.
Three different coplanar treatment plans were created for four patients, comprising a two-arc VMAT plan as well as 5-field and 9-field IMRT plans with 6 MV beams. The X-ray Voxel Monte Carlo algorithm was employed for dose calculation. A radiation therapy dose of 60 Gy was prescribed to the planning target volume (PTV) in 30 fractions. The homogeneity indexes (HIs) and conformity indexes (CIs) of the PTV, organs at risk (OARs) doses and delivery times were calculated and compared.
For the VMAT, 5-field and 9-field IMRT plans, the mean HIs were 0.14, 0.16 and 0.15; CIs were 0.63, 0.61 and 0.64; CIs were 0.72, 0.66 and 0.70 and CIs were 0.74, 0.67 and 0.71 respectively. All mean dose parameters of the VMAT and 9-field IMRT plans for the brain were equal to or lower than those of the 5-field IMRT plan. For the 5-field IMRT plan, the dose constraints for the left lens were not satisfied in two patients. The mean delivery times were 3.3, 11.1 and 14.7 min for the VMAT, 5-field and 9-field IMRT plans respectively.
The VMAT plan quality is comparable to that of 9-field IMRT, with a reduced delivery time. Therefore, VMAT represents a valuable, sophisticated irradiation technique for treating scalp angiosarcoma.
由于头皮血管肉瘤的表面呈球形，在放射治疗计划制定和剂量输送方面需要仔细考虑。在此，我们研究了容积调强弧形放疗（VMAT）在计划质量和输送时间方面是否优于调强放射治疗（IMRT）。
为4例患者制定了三种不同的共面治疗计划，包括一个双弧VMAT计划以及5野和9野IMRT计划，使用6兆伏的射线束。采用X射线体素蒙特卡罗算法进行剂量计算。计划靶区（PTV）的放射治疗剂量规定为60 Gy，分30次给予。计算并比较了PTV的均匀性指数（HIs）和适形指数（CIs）、危及器官（OARs）剂量和输送时间。
对于VMAT、5野和9野IMRT计划，平均HIs分别为0.14、0.16和0.15；CIs分别为0.63、0.61和0.64；CIs分别为0.72、0.66和0.70，以及CIs分别为0.74、0.67和0.71。VMAT和9野IMRT计划对脑的所有平均剂量参数均等于或低于5野IMRT计划。对于5野IMRT计划，两名患者的左眼晶状体剂量限制未得到满足。VMAT、5野和9野IMRT计划的平均输送时间分别为3.3分钟、11.1分钟和14.7分钟。
VMAT计划质量与9野IMRT相当，且输送时间缩短。因此，VMAT是治疗头皮血管肉瘤的一种有价值的、先进的照射技术。
