Henjum Helge, Mo Feten Karoline, Hartvigsen Erlend, S Ytre-Hauge Kristian, Boer Camilla G, H Stokkevåg Camilla
Department of Physics and Technology, University of Bergen, Bergen, Norway.
Department of Physics and Technology, University of Bergen.
Acta Oncol. 2025 May 12;64:654-660. doi: 10.2340/1651-226X.2025.42001.
Proton Arc Therapy (PAT) is an emerging proton therapy treatment modality with the potential to reduce radiation exposure to healthy tissues compared to conventional Intensity-Modulated Proton Therapy (IMPT) with fewer beams. This is an attractive option for treating pediatric patients, who are vulnerable to radiation-induced side effects. There is, however, a need to investigate the redistribution of dose to the target volume and organs at risk. In this study, we therefore explored the potential of PAT in proton therapy of pediatric ependymoma.
Three-field IMPT and PAT treatment plans for 10 pediatric ependymoma patients were optimized using the Eclipse treatment planning system. The PAT plans consisted of 8 fields, spanning 170 degrees. Both modalities were robustly optimized with a ± 2 mm isocenter shift and a ± 3% range uncertainty.
PAT showed improved CTV coverage compared to three-field IMPT, with a distinct increase in D98%. A clear dose reduction was found for the cochleae, with median values of 9.32 Gy(Relative Biological Effectiveness [RBE]) [0.76 - 30.40 Gy(RBE)] and 18.30 Gy(RBE) [1.24 - 29.75 Gy(RBE)] for PAT and IMPT, respectively, for the right cochlea. For the left cochlea, the respective doses were 12.34 Gy(RBE) [2.81 - 30.94 Gy(RBE)] and 18.49 Gy(RBE) [4.27 - 31.97 Gy(RBE)]. No significant difference for the brain integral dose was found between the two modalities.
PAT can improve the dosimetric outcome of proton therapy in pediatric ependymoma patients. Organs at risk dose varied on a patient-to-patient basis; thus, individual treatment plan comparisons are recommended.
质子弧形治疗（PAT）是一种新兴的质子治疗方式，与传统的少束流调强质子治疗（IMPT）相比，它有可能减少对健康组织的辐射暴露。对于易受辐射诱导副作用影响的儿科患者而言，这是一个有吸引力的选择。然而，有必要研究靶区体积和危及器官的剂量重新分布情况。因此，在本研究中，我们探讨了PAT在儿科室管膜瘤质子治疗中的潜力。
使用Eclipse治疗计划系统为10例儿科室管膜瘤患者优化了三野IMPT和PAT治疗计划。PAT计划由8个野组成，覆盖170度。两种方式均在等中心±2mm移位和±3%射程不确定性的情况下进行了稳健优化。
与三野IMPT相比，PAT显示出更好的临床靶区（CTV）覆盖，D98%有明显增加。发现耳蜗的剂量明显降低，右侧耳蜗PAT和IMPT的中位值分别为9.32 Gy（相对生物效应[RBE]）[0.76 - 30.40 Gy（RBE）]和18.30 Gy（RBE）[1.24 - 29.75 Gy（RBE）]。左侧耳蜗的相应剂量分别为12.34 Gy（RBE）[2.81 - 30.94 Gy（RBE）]和18.49 Gy（RBE）[4.27 - 31.97 Gy（RBE）]。两种方式之间脑积分剂量未发现显著差异。
PAT可改善儿科室管膜瘤患者质子治疗的剂量学结果。危及器官的剂量因患者而异；因此，建议进行个体治疗计划比较。
