A team has carried out a dosimetric evaluation and optimised beam energy for proton therapy in the treatment of Hodgkin's lymphoma using a Monte Carlo simulation framework built on GATE, the radiation transport simulation code developed on top of Geant4. The work addresses the need to characterise dose deposition accurately in proton therapy treatments targeting mediastinal regions, where the proximity of critical organs such as the heart and lungs demands tight control of the dose profile.

Proton therapy offers a physical advantage over photon radiotherapy thanks to the Bragg peak, which concentrates most of the released energy at a well-defined depth and reduces the dose deposited in healthy tissue. That advantage, however, depends critically on beam energy, which sets the depth at which protons come to rest inside the patient's body. Optimising that energy for each clinical case is therefore an essential step in treatment planning.

The method relies on GATE to simulate proton transport through the patient's anatomy, reproducing particle interactions with tissue and calculating the three-dimensional distribution of deposited dose. This Monte Carlo approach allows both the beam and the heterogeneity of the traversed media to be modelled realistically, something particularly relevant in the thoracic region, where density changes between lung, bone and soft tissue alter the range of the protons.

The resulting dosimetric evaluation allows the dose distribution obtained to be compared with the clinical objectives of the treatment and the beam energy to be adjusted to maximise coverage of the target volume while minimising irradiation of healthy structures. The proposed framework is presented as a tool for the planning and verification of proton therapy plans in Hodgkin's lymphoma, with potential to extend to other tumour types in which dosimetric precision is decisive.