Narita Memorial Proton Center, Toyohashi, Aichi, Japan.
38386Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan.
Technol Cancer Res Treat. 2021 Jan-Dec;20:15330338211060170. doi: 10.1177/15330338211060170.
Cognitive decline and alopecia after radiotherapy are challenging problems. We aimed to compare whole brain radiotherapy (WBRT) plans reducing radiation dose to the hippocampus and scalp between helical tomotherapy (HT) and intensity-modulated proton therapy (IMPT). We conducted a planning study of WBRT for 10 patients. The clinical target volume was defined as the whole brain excluding the hippocampus avoidance (HA) region. The prescribed dose was 30 Gy in 10 fractions to cover 95% of the target. Constraint goals were defined for the target and organs at risk (OAR). Both techniques met the dose constraints for the target and OAR. However, the coverage of the target (dose covering 95% [D95%] and 98% [D98%] of the volume) were better in IMPT than HT (HT vs IMPT: D95%, 29.9 Gy vs 30.0 Gy, < .001; D98%, 26.7 Gy vs 28.1 Gy, = .002). The homogeneity and conformity of the target were also better in IMPT than HT (HT vs IMPT: homogeneity index, 1.50 vs 1.28, < .001; conformity index, 1.30 vs 1.14, < .001). IMPT reduced the D100% of the hippocampus by 59% (HT vs IMPT: 9.3 Gy vs 3.8 Gy, < .001) and reduced the Dmean of the hippocampus by 37% (HT vs IMPT: 11.1 Gy vs 7.0 Gy, < .001) compared with HT. The scalp IMPT reduced the percentage of the volume receiving at least 20 Gy (V20Gy) and V10Gy compared with HT (HT vs IMPT: V20Gy, 56.7% vs 6.6%, < .001; V10Gy, 90.5% vs 37.1%, < .001). Both techniques provided acceptable target dose coverage. Especially, IMPT achieved excellent hippocampus- and scalp-sparing. HA-WBRT using IMPT is a promising treatment to prevent cognitive decline and alopecia.
放疗后认知能力下降和脱发是具有挑战性的问题。我们旨在比较螺旋断层放疗（HT）和强度调制质子治疗（IMPT）降低海马体和头皮放射剂量的全脑放疗（WBRT）计划。我们对 10 例患者进行了 WBRT 计划研究。临床靶区定义为全脑，不包括海马体回避（HA）区域。处方剂量为 30 Gy，分 10 次给予，以覆盖 95%的靶区。为靶区和危及器官（OAR）定义了约束目标。两种技术均满足靶区和 OAR 的剂量限制。然而，与 HT 相比，IMPT 更好地覆盖了靶区（目标覆盖 95%[D95%]和 98%[D98%]的体积）（HT 与 IMPT：D95%，29.9 Gy 与 30.0 Gy，<.001；D98%，26.7 Gy 与 28.1 Gy，=.002）。IMPT 也更好地改善了靶区的均匀性和适形性（HT 与 IMPT：均匀性指数，1.50 与 1.28，<.001；适形性指数，1.30 与 1.14，<.001）。与 HT 相比，IMPT 降低了海马体 D100%剂量 59%（HT 与 IMPT：9.3 Gy 与 3.8 Gy，<.001），降低了海马体 Dmean 剂量 37%（HT 与 IMPT：11.1 Gy 与 7.0 Gy，<.001）。与 HT 相比，头皮 IMPT 降低了至少 20 Gy（V20Gy）和 10 Gy（V10Gy）的体积百分比（HT 与 IMPT：V20Gy，56.7%与 6.6%，<.001；V10Gy，90.5%与 37.1%，<.001）。两种技术均提供了可接受的靶区剂量覆盖。特别是，IMPT 实现了优异的海马体和头皮保护。使用 IMPT 的 HA-WBRT 是预防认知能力下降和脱发的一种有前途的治疗方法。
