Burlile Jessica F, Shiraishi Satomi, Gunn Heather J, Bradt Jennifer L, Kroeplin Haley M, Lang Karen G, Cimmiyotti Jenna K, Depauw Nicolas, Chang Connie Y, Brom Kevin M, Sonnicksen Cassandra L, Vu Anhmai, Jimenez Rachel B, Corbin Kimberly S
Mayo Clinic Department of Radiation Oncology, Rochester, MN, USA.
Mayo Clinic Department of Medical Physics, Rochester, MN, USA.
Acta Oncol. 2024 Oct 1;63:755-762. doi: 10.2340/1651-226X.2024.40084.
Regional nodal irradiation (RNI) for breast cancer delivers radiation in proximity to the shoulder and torso, and radiation exposure may contribute to long-term upper extremity and postural morbidity. To date, no studies have assessed the differential dosimetric impact of proton versus photon radiation on shoulder and torso anatomy. This study examined clinically relevant musculoskeletal (MSK) structures and assessed the dose delivered with each modality.
PATIENTS/MATERIAL AND METHODS: Ten MSK structures were contoured on IMPT (intensity-modulated proton therapy) and VMAT (volumetric modulated arc therapy) plans for 30 patients receiving RNI. Relevant dose metrics were compared for each of the structures. Intensity-modulated proton therapy dose was calculated using the relative biological effective value of 1.1. Hypo-fractionated plans were scaled to the equivalent dose in 2 Gy fractions (EQD2) using an alpha/beta ratio of four. Wilcoxon signed rank sum tests compared doses. Select three-dimensional and optimised VMAT plans were also informally compared.
Each of the 10 structures received a statistically significantly lower dose with the use of IMPT compared with VMAT. Differences were greatest for posterior structures, including the trapezius, latissimus dorsi and glenohumeral joint. Mean absolute differences were as great as 23 Gy (supraspinatus D5cc) and up to 30-fold dose reductions were observed (deltoid D50cc). An average 3.7-fold relative dose reduction existed across all structures. Measures of low/intermediate dose (V15Gy and D50cc) showed the largest differences. Intensity-modulated proton therapy results in statistically lower radiation exposure to relevant shoulder and torso anatomy compared to photon radiation for patients requiring RNI. Prospective study is needed to correlate functional outcomes with radiation dose.
乳腺癌区域淋巴结照射（RNI）时，辐射靠近肩部和躯干，辐射暴露可能导致长期上肢和姿势性疾病。迄今为止，尚无研究评估质子与光子辐射对肩部和躯干解剖结构的剂量差异影响。本研究检查了临床相关的肌肉骨骼（MSK）结构，并评估了每种方式所给予的剂量。
患者/材料与方法：在30例接受RNI的患者的调强质子治疗（IMPT）和容积调强弧形治疗（VMAT）计划上勾勒出10个MSK结构。比较每个结构的相关剂量指标。使用相对生物效应值1.1计算调强质子治疗剂量。使用α/β比值为四，将大分割计划缩放到2 Gy分次的等效剂量（EQD2）。采用Wilcoxon符号秩和检验比较剂量。还对选定的三维和优化VMAT计划进行了非正式比较。
与VMAT相比，使用IMPT时10个结构中的每一个所接受的剂量在统计学上均显著降低。后位结构差异最大，包括斜方肌、背阔肌和盂肱关节。平均绝对差异高达23 Gy（冈上肌D5cc），观察到剂量降低高达30倍（三角肌D50cc）。所有结构的平均相对剂量降低3.7倍。低/中剂量测量值（V15Gy和D50cc）显示差异最大。对于需要RNI的患者而言，与光子辐射相比，调强质子治疗导致相关肩部和躯干解剖结构的辐射暴露在统计学上更低。需要进行前瞻性研究以将功能结果与辐射剂量相关联。
