Estudo do perfil de feixe de fótons em LINAC

Abstract

This study aimed to evaluate potential deviations in the flatness and symmetry of the photon beam produced by a Precise linear accelerator manufactured by Elekta, installed at the Fundação de Beneficência Hospital de Cirurgia (FBHC). Due to the unavailability of the automatic scanning system, tests were performed manually by measuring dose point by point using an ionization chamber immersed in a water-filled phantom. Fields of 10 × 10 cm² and 30 × 30 cm² were analyzed, with beam energies of 6 MeV and 10 MeV, following the guidelines of the manufacturer’s manual (Elekta) and the recommendations of the International Atomic Energy Agency (IAEA). The measured results were compared with those generated by the MONACO V6.3.3 treatment planning system, in order to ensure the reliability of the clinical parameters. The measurements allowed for the construction of dose profiles, through which beam uniformity was evaluated. The results showed no significant deviations in flatness and symmetry, with all values remaining within the recommended tolerance limits, according to both the Elekta manual and IAEA guidelines. Additionally, beam penetration quality tests confirmed that the beam maintains adequate depth-dose characteristics, which are essential for therapeutic effectiveness. However, discrepancies were observed between the measured data and the treatment planning system results, indicating a need for technical improvements, such as the use of CT images with thinner slices, to increase dose calculation accuracy. Nevertheless, these differences did not compromise the beam profile, which remained within acceptable limits. It is therefore concluded that the dose distribution delivered to the target volume is consistent with the planned values, ensuring the quality and safety of radiotherapy treatments.