Skin dose effects of postmastectomy chest wall radiation therapy using brass mesh as an alternative to a bolus.

Abstract

157 Background: The use of brass mesh as an alternative to a bolus is relatively uncommon in post-mastectomy chest wall radiation therapy (PMRT). This study aimed to characterize the skin dose effects of using 2mm fine brass mesh as an alternative to the traditional tissue-equivalent bolus during chest wall PMRT. Methods: Data was collected from patients who received PMRT using brass mesh at UC Davis Medical Center’s Department of Radiation Oncology between January 2008 and June 2011. Several patient characteristics including age, body habitus, and ethnicity were analyzed along with several disease and treatment characteristics to determine whether or not they had an impact on the skin reaction observed during radiation treatment. In addition to assessing skin toxicity visually using standardized National Cancer Institute scores (NCIS), surface doses were measured for 16 of the 48 patients (33%) to quantify radiation exposure to the chest wall. Results: 48 female patients aged 28-83 received PMRT using brass mesh. As expected, the severity of skin toxicity increased with subsequent doses of radiation with all patients beginning treatment with no skin reaction (NCIS = 0) and the majority of patients completing treatment with either faint to moderate erythema (N = 19, 40%, NCIS = 1) or moderate to brisk erythema (N = 23, 48%, NCIS = 2). In vivo dosimetry analysis revealed surface doses between 81% and 110% of the prescribed dose, with an average of 99% of the prescribed radiation dose being delivered and a standard deviation of 10%. Conclusions: For post-mastectomy chest wall radiation therapy, brass mesh is an effective alternative to the tissue-equivalent bolus. The brass mesh achieved moderate erythema in the majority of patients at the end of treatment and the surface dose was validated using in vivo dosimetry.