Monte Carlo assessment of a treatment planning system for intraoperative radiotherapy in the presence of tissue heterogeneities
Aurora Corso, F. Javier Jimenez‐Albericio, Michele Avanzo, Pablo Ortega‐Pardina, Roberto Cirio, Daniel Vera‐Tena, Elena Gonzalez‐Gonzalez, Alejandro Garcia‐RomeroAbstract
Background
Radiance is a Monte Carlo−based treatment planning software integrated into the Intrabeam system for 50‐kVp X‐rays intraoperative radiotherapy (IORT).
Purpose
This study evaluates Radiance accuracy in calculating absorbed dose in IORT of the breast including the effect of tissue heterogeneities.
Methods
Dose distributions from IORT were calculated in 88 virtual phantoms of different tissue‐equivalent materials. Dose was calculated independently using the penEasy code for the PENELOPE Monte Carlo engine and compared to Radiance. Depth dose curves (DDCs) were compared through gamma analysis using 5%/0.5 mm and 3%/0.5 mm criteria.
Results
When comparing Radiance vs penEasy all passing rates were above 95%. Notable differences from dose to water emerged for some tissues: cortical bone absorbed about four times more than water, while adipose tissue received about 45% less. These variations were affected by atomic number more than density.
Conclusion
Radiance results show strong agreement with penEasy simulations. Furthermore, it was observed that IORT absorbed doses can fluctuate by ± 50% due to heterogeneities surrounding the applicator. This highlights that the prescribed dose and the absorbed dose in the applicator surface do not necessarily coincide in non‐water tissues, emphasizing the critical need to account for specific tissue characteristics during treatment planning.