Dosimetry in radiotherapy

Dosimetry is the step in which a dosimetrist or a medical physicist calculates how to deliver the dose prescribed by the radiation oncologist (e.g. radiation beam energy, number of beams etc.) The aim of dosimetry is to calculate how the ionizing radiation (photons, electrons, protons) will be delivered to the region of interest The aim of dosimetry is to calculate how the ionizing radiation (photons, electrons, protons) will be delivered to the region of interest (i.e. the tumor located in the irradiation field), while sparing healthy tissues as much as possible. Mathematical algorithms (such as the “Monte Carlo” method) are used to simulate the energy deposited (i.e. the radiation dose) in

the various areas (tumor, organs at risk) identified and delineated by the physician on the images acquired during the CT simulation scan. This dosimetric calculation will be adjusted until the desired dose values are obtained for the different tissues (i.e. highest dose for the tumor without exceeding the maximum doses for the healthy tissues). The dosimetric plan will then be validated by the radiation oncologist before treatment initiation.