Scientific visitor PT 3D dose mapping
The use of proton therapy (PT) techniques is highly recommended in paediatric patients since they allow for a more localized dose deposition compared to other techniques, resulting in a reduction of the undesired dose to surrounding healthy tissues. However, secondary neutrons are generated as byproducts of proton reactions with the beam line components and the patient itself, contributing to the total dose received by the patient. Although doses due to neutrons are low compared to the primary proton dose, they increase the risks of suffering from induced cancers in the future—especially in children—becoming an issue of major concern and justifying the need to better understand the interaction of the generated neutrons with both the patient and the treatment room components. To properly characterize these neutron interactions and their dosimetric impact, experimental and computational procedures are required. Experimental measurements in anthropomorphic phantoms are required to assess neutron doses at relevant positions and to validate Monte Carlo simulations. Since these measurements provide dose information only at discrete locations, validated Monte Carlo models are essential to obtain detailed organ dose distributions. Once validated, these models can provide 3D dose mapping of the most exposed organs and enable more personalized dosimetric assessments adapted to specific treatment conditions.
The main objective of the research stay is to assess 3D organ dose distributions during paediatric brain PT.
To this aim, the following objectives will be addressed.
- Create a Monte Carlo beam model for a specific paediatric brain PT case, namely the HARMONIC patient case irradiated in IBA ProteusPlus (Essen, Germany) within both TOPAS and MCNP.
- Load the five-year-old anthropomorphic phantom geometry including detector and organ segmentation maps.
- Calculate the doses in the detector positions and comparison to experimental measurements, evaluating whether the designed Monte Carlo model reproduces the neutron and non-neutron doses.
- Calculate 3D organ doses, within the five-year-old anthropomorphic phantom as well as in ICRP phantoms of similar and different age groups.