Benefit of replacing the Sigma-60 by the Sigma-Eye applicator: A Monte Carlo-based uncertainty analysis

Background and purpose To investigate the clinical benefit of replacing the BSD-2000 Sigma-60 with the Sigma-Eye applicator, taking into account effects of uncertainties in tissue and water bolus parameters. Patients and methods For 20 patients, specific absorption rate (SAR) and temperature distributions were calculated and optimized, based on computed tomography (CT) scans in treatment position. The impact of uncertainties on predicted distributions was studied using a Monte Carlo uncertainty assessment. Results Replacing the Sigma-60 by the Sigma-Eye applicator resulted in a higher SAR in the tumor [on average a decrease of the hotspot tumor quotient (HTQ) by 24%; p