Assessing proton plans with three different beam delivery systems versus photon plans for head and neck tumors

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING Journal of Applied Clinical Medical Physics Pub Date : 2025-02-17 DOI:10.1002/acm2.70013

Tara Gray, Chieh-Wen Liu, Saeed Ahmed, Anna Maria Kolano, Jeremy Donaghue, Shlomo Koyfman, Neil Woody, Shauna R. Campbell, Jonathan B. Farr, Ping Xia

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Abstract

Purpose

To compare plan quality among photon volumetric modulated arc therapy (VMAT) and intensity-modulated proton therapy (IMPT) with robustness using three different proton beam delivery systems with various spot size (σ) ranges: cyclotron-generated proton beams (CPBs) (σ: 2.7–7.0 mm), linear accelerator proton beams (LPBs) (σ: 2.9–5.5 mm), and linear accelerator proton mini beams (LPMBs) (σ: 0.8–3.9 mm) for the treatment of head and neck (HN) cancer with bilateral neck irradiation.

Methods

Ten patients treated for oropharynx cancer with bilateral neck irradiation were planned using CPBs, LPBs, LPMBs, and VMAT. The homogeneity index (HI), mean body dose, and defined volumetric doses for selected critical organs-at-risk (OARs) were compared. Set-up uncertainties of ±3 mm and ± 3.5% range uncertainties were included in robust evaluation using V_95%Rx> 95% (Volume that covers 95% of the target volume at 95% of the prescription (Rx) dose) to high dose and low dose CTV volumes (CTV_70 Gy and CTV_56 Gy). VMAT and proton plans were compared in terms of OAR doses and mean body dose only. Homogeneity Indices were compared among IMPT plans in addition to OAR doses. The Wilcoxon signed-rank test was used to evaluate statistical differences between evaluation metrics for VMAT plans and all proton plan types.

Results

OAR dose metrics were improved by 2% to 30% from CPB plans to LPB or LPMB plans. Compared to photon VMAT plans, all OAR doses except for mandible dose metrics were improved by 2% to 53% for all proton plans. The mean body dose was also improved by 7.5% from CPB to LPB and by 10.8% from CPB to LPMB. In addition, the mean body dose was also improved by 44% from VMAT to CPB, by 48% from VMAT to LPB, and by 50% from VMAT to LPMB plans. Compared to CPB plans, HI was significantly better (p < 0.05) for the LPB and LPMB plans. HI also improved considerably from VMAT to CPB, LPB, and LPMB. For both CTV_70 Gy and CTV_56 Gy, average robust evaluation across all worst-case scenarios was slightly better for CPB plans, with an average of V_95%Rx of the CTV_70 Gy of 97.6% ± 1.22%, followed by 97.2% ± 1.31% and 97.2% ± 1.35% for LPB and LPMB plans, respectively. Robustness for CTV_56 Gy showed comparable robustness across all proton plan types, with an average V_95%Rx of 97.4% ± 0.87% for CPB, 97.4% ± 1.21%, and 97.5% ± 1.08% for CPB, LPB, and LPMB plans, respectively.

Conclusion

With decreased spot size, the LPB and LPMB are excellent alternatives to VMAT and CPB therapy and can significantly reduce the dose to normal tissue.

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头颈部肿瘤的三种不同光束传输系统的质子计划与光子计划的评估。

目的：比较光子体积调制电弧治疗（VMAT）和强度调制质子治疗（IMPT）在双侧颈部放射治疗头颈部癌时，使用三种不同光斑大小（σ）范围的质子束输送系统：回旋产生质子束（CPBs）（σ: 2.7 ~ 7.0 mm）、直线加速器质子束（LPBs）（σ: 2.9 ~ 5.5 mm）和直线加速器质子微束（LPMBs）（σ: 0.8 ~ 3.9 mm），在鲁棒性方面的计划质量。方法：对10例双侧颈部放射治疗口咽癌患者分别采用CPBs、LPBs、LPMBs和VMAT进行治疗。比较了均匀性指数（HI）、平均体剂量和选定关键危险器官（OARs）的定义体积剂量。使用V95%Rx > 95%（在95%处方（Rx）剂量下覆盖95%目标体积的体积）到高剂量和低剂量CTV体积（CTV_70 Gy和CTV_56 Gy）进行稳健评估时，设置不确定度为±3 mm和±3.5%范围不确定度。VMAT和质子计划仅在OAR剂量和平均体剂量方面进行比较。除了OAR剂量外，还比较了IMPT计划之间的均匀性指数。采用Wilcoxon符号秩检验来评价VMAT计划和所有质子计划类型评估指标之间的统计学差异。结果：从CPB计划到LPB或LPMB计划，OAR剂量指标提高了2%至30%。与光子VMAT计划相比，除了下颌骨剂量指标外，所有质子计划的所有OAR剂量都提高了2%至53%。从CPB到LPB的平均体剂量也提高了7.5%，从CPB到LPMB的平均体剂量提高了10.8%。此外，VMAT计划到CPB计划的平均体剂量也提高了44%，VMAT计划到LPB计划提高了48%，VMAT计划到LPMB计划提高了50%。与CPB计划相比，HI计划的CTV_70 Gy的p 95%Rx为97.6%±1.22%，LPB和LPMB计划分别为97.2%±1.31%和97.2%±1.35%。CTV_56 Gy的稳健性在所有质子计划类型中表现出相当的稳健性，CPB计划的平均V95%Rx为97.4%±0.87%，CPB， LPB和LPMB计划的V95%Rx分别为97.4%±1.21%和97.5%±1.08%。结论：LPB和LPMB是VMAT和CPB治疗的较好替代方案，可显著降低对正常组织的剂量。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Applied Clinical Medical Physics 医学-核医学

CiteScore

3.60

自引率

19.00%

发文量

331

审稿时长

3 months

期刊介绍： Journal of Applied Clinical Medical Physics is an international Open Access publication dedicated to clinical medical physics. JACMP welcomes original contributions dealing with all aspects of medical physics from scientists working in the clinical medical physics around the world. JACMP accepts only online submission. JACMP will publish: -Original Contributions: Peer-reviewed, investigations that represent new and significant contributions to the field. Recommended word count: up to 7500. -Review Articles: Reviews of major areas or sub-areas in the field of clinical medical physics. These articles may be of any length and are peer reviewed. -Technical Notes: These should be no longer than 3000 words, including key references. -Letters to the Editor: Comments on papers published in JACMP or on any other matters of interest to clinical medical physics. These should not be more than 1250 (including the literature) and their publication is only based on the decision of the editor, who occasionally asks experts on the merit of the contents. -Book Reviews: The editorial office solicits Book Reviews. -Announcements of Forthcoming Meetings: The Editor may provide notice of forthcoming meetings, course offerings, and other events relevant to clinical medical physics. -Parallel Opposed Editorial: We welcome topics relevant to clinical practice and medical physics profession. The contents can be controversial debate or opposed aspects of an issue. One author argues for the position and the other against. Each side of the debate contains an opening statement up to 800 words, followed by a rebuttal up to 500 words. Readers interested in participating in this series should contact the moderator with a proposed title and a short description of the topic