de Jong Bas, Maring Anneke, Werkman Chimène, Sundström Johan, Cannavò Daniele, van der Schaaf Arjen, Scandurra Daniel, Engwall Erik, Korevaar Erik W, Janssens Guillaume, Langendijk Johannes A, Both Stefan
Department of Radiation Oncology, University of Groningen, Hanzeplein 1, Groningen, 9700 RB, NETHERLANDS.
Department of Radiation Oncology, University of Groningen, Hanzeplein 1, Groningen, 9700 AB, NETHERLANDS.
Phys Med Biol. 2025 Apr 25. doi: 10.1088/1361-6560/add103.
Radiotherapy (RT) in nasopharyngeal cancer (NPC) patients presents challenges due to proximity of many anatomical structures to the target volume. Furthermore, inter-fractional changes must be considered to assure target coverage. Proton arc therapy (PAT) potentially reduces healthy tissue dose compared to IMPT and VMAT. The impact of PAT on dose to organs-at-risk (OARs), predicted acute- and late radiation toxicities and robust target coverage to inter-fraction changes in NPC patients were investigated. Approach: Robustly optimized PAT plans were compared to clinical VMAT and IMPT plans for 10 NPC patients treated with 70.00 Gy to the primary target (CTV 7000) and 54.25 Gy to the prophylactic lymph nodal area (CTV 5425). Integral body dose and mean and max in 0.03cc dose (Dmean and max D0.03cc) in OARs were compared. Normal tissue complication probability (NTCP) values for 22 acute and late radiation-induced toxicities were evaluated. A PAT "base approach" and nine PAT planning approaches to improve PAT inter-fraction robust target coverage were investigated. Target coverage was evaluated on in total 54 weekly repeated CT images (rCTs). Main Results: PAT integral dose reduced by on average 55% and 15% compared with clinical VMAT and IMPT, respectively. Compared to IMPT, average Dmean and max D0.03cc were significantly reduced in all evaluated neurological structures. Compared to IMPT, in the PAT plans Dmean was reduced most in the arytenoids, PCM medius and brainstem by on average 8.0 Gy, 6.4 Gy and 6.1 Gy, respectively and all evaluated NTCP's for both acute and late timepoint were significantly reduced. Compared with IMPT, PAT base approach target coverage on rCTs was worse. Approaches to improve PAT inter-fraction target coverage were successful, while maintaining the reduction in NTCP compared to IMPT. Significance: Compared to IMPT and VMAT, PAT reduces healthy tissue dose and subsequent estimated toxicity risks in NPC patients. PAT planning approaches to improve inter-fraction robustness were employed successfully, while NTCP benefits of PAT were maintained.
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由于许多解剖结构与鼻咽癌（NPC）患者的靶区相邻，因此鼻咽癌患者的放射治疗（RT）面临挑战。此外，必须考虑分次间的变化以确保靶区覆盖。与调强质子治疗（IMPT）和容积旋转调强放疗（VMAT）相比，质子弧形治疗（PAT）可能会降低健康组织的剂量。研究了PAT对NPC患者危及器官（OARs）剂量、预测的急性和晚期放射毒性以及对分次间变化的稳健靶区覆盖的影响。
将10例NPC患者的稳健优化PAT计划与临床VMAT和IMPT计划进行比较，这些患者的原发靶区（CTV 7000）接受70.00 Gy照射，预防性淋巴引流区（CTV 5425）接受54.25 Gy照射。比较了OARs中的总体积剂量以及0.03cc剂量中的平均值和最大值（Dmean和max D0.03cc）。评估了22种急性和晚期放射诱导毒性的正常组织并发症概率（NTCP）值。研究了一种PAT“基础方法”和九种改善PAT分次间稳健靶区覆盖的PAT计划方法。在总共54张每周重复的CT图像（rCTs）上评估靶区覆盖情况。
与临床VMAT和IMPT相比，PAT的总体积剂量分别平均降低了55%和15%。与IMPT相比，所有评估的神经结构中的平均Dmean和max D0.03cc均显著降低。与IMPT相比，在PAT计划中，杓状软骨、内侧翼状肌和脑干中的Dmean平均分别降低了8.0 Gy、6.4 Gy和6.1 Gy，并且所有评估的急性和晚期时间点的NTCP均显著降低。与IMPT相比，PAT基础方法在rCTs上的靶区覆盖较差。改善PAT分次间靶区覆盖的方法是成功的，同时与IMPT相比保持了NTCP的降低。
与IMPT和VMAT相比，PAT降低了NPC患者的健康组织剂量以及随后估计的毒性风险。成功采用了改善分次间稳健性的PAT计划方法，同时保持了PAT的NTCP益处。
