EXaSkin: A novel high-density bolus for 6MV X-rays radiotherapy. (December 2020)

• Record Type: Journal Article
• Authors: Al-sudani, Taghreed A.; Biasi, Giordano; Wilkinson, Dean; Davis, Jeremy A.; Kearnan, Royce; Matar, Fatima S.; Cutajar, Dean L.; Metcalfe, Peter; Rosenfeld, Anatoly B.
• Is Part Of: Physica medica. Volume 80(2021)
• Page Start: 42
• Page End: 46
• Publication Date: 2020-12
• Subjects: eXaSkin bolus -- VMAT -- Skin dose -- Head and neck; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2020.09.002
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: Evaluation of a novel high-density bolus alternative to tissue-equivalent Superflab. eXaSkin, the novel bolus, had superior adaptation to the skin surface. eXaSkin allowed for accurate positioning and reproducibility of set-up conditions. eXaSkin provided sufficient build-up to achieve full skin dose with less material. Abstract: Purpose: To evaluate eXaSkin, a novel high-density bolus alternative to commercial tissue-equivalent Superflab, for 6MV photon-beam radiotherapy. Materials and methods: We delivered a 10 × 10 cm 2 open field at 90° and head-and-neck clinical plan, generated with the volumetric modulated arc therapy (VMAT) technique, to an anthropomorphic phantom in three scenarios: with no bolus on the phantom's surface, with Superflab, and with eXaSkin. In each scenario, we measured dose to a central planning target volume (PTV) in the nasopharynx region with an ionization chamber, and we measured dose to the skin, at three different positions within the vicinity of a neck lymph node PTV, with MO Skin ™, a semiconductor dosimeter. Measurements were compared against calculations with the treatment planning system (TPS). Results: For the static field, MO Skin results underneath the eXaSkin were in agreement with calculations to within 1.22%; for VMAT, to within 5.68%. Underneath Superflab, those values were 3.36% and 11.66%. The inferior agreement can be explained by suboptimal adherence of Superflab to the phantom's surface as well as difficulties in accurately reproducing its placement between imaging and treatment session. In all scenarios, dose measured at the central target agreed to within 1% with calculations. Conclusions: eXaSkin was shown to have superior adaptation to the phantom's surface, producing minimal air gaps between the skin surface and bolus, allowing for accurate positioning and reproducibility of set-up conditions. eXaSkin with its high density material provides sufficient build-up to achieve full skin dose with less material thickness than Superflab.