Monte Carlo simulations and radiation dosimetry measurements of peripherally applied HDR I 192 r breast brachytherapy D‐shaped applicators

Conformal dose coverage for accelerated partial breast irradiation or radiotherapy boost can be obtained with AccuBoost® D‐shaped brachytherapy applicators using a flattened surface positioned near the patient. Three D‐shaped applicators (D45/D53/D60) were dosimetrically characterized using Monte Carlo methods (MCNP5), air ionization chambers (Farmer and Markus), and radiochromic film (GafChromic EBT) in polystyrene and ICRU 44 breast tissue. HDRI192 r source dwell times were either constant or optimized to improve skin dose uniformity. Scatter dose decreased as depth decreased. 10 mm beyond the applicator aperture, dose reductions of 90% and 51% were observed at depths of 0 and 30 mm, respectively. Similarly, planar dose uniformity improved as depth decreased and was also due to scatter and applicator geometry. Dose uniformity inside the applicator aperture was approximately 11% and 15% for all three applicators at the skin and 30 mm deep, respectively. Depth dose measurements in polystyrene using ion chamber and radiochromic film agreed with Monte Carlo results within 2%. Discrepancies between film and Monte Carlo dose profiles at 30 mm depth were within 1%.