Jessica F Burlile, Satomi Shiraishi, Heather J Gunn, Jennifer L Bradt, Haley M Kroeplin, Karen G Lang, Jenna K Cimmiyotti, Nicolas Depauw, Connie Y Chang, Kevin M Brom, Cassandra L Sonnicksen, Anhmai Vu, Rachel B Jimenez, Kimberly S Corbin
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引用次数: 0
Abstract
Background and purpose: 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.
Results and interpretation: 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.
期刊介绍:
Acta Oncologica is a journal for the clinical oncologist and accepts articles within all fields of clinical cancer research. Articles on tumour pathology, experimental oncology, radiobiology, cancer epidemiology and medical radio physics are also welcome, especially if they have a clinical aim or interest. Scientific articles on cancer nursing and psychological or social aspects of cancer are also welcomed. Extensive material may be published as Supplements, for which special conditions apply.