Dose profile evaluation of a 6 MV beam in a field of 5 x 5 cm²

Radiotherapy is a treatment of malignant tumors aiming at their elimination or the inhibition of their growth, using irradiation techniques increasingly collimated. There are innovations in conformation methodologies, with the objective of greater preservation of healthy tissues surrounding tumor tissues. In this work, the dose distribution of an X-ray beam was recorded using a solid water phantom, for an irradiation field with 5 x 5 cm². The 6 MV X-ray beam was generated in a linear accelerator model Synergy from the manufacturer Elekta, and radiochromic film sheets were used to record dose profiles inside a solid water phantom. The solid water phantom loaded with radiochromic film was positioned 1 m away from the X-ray beam's focus. The longitudinal profile of absorbed dose obtained presented the maximum dose value at 1.09 cm of depth, inside the phantom. For depth of 2.6 cm the dose was still 95% of the maximum dose value, and at 10 cm depth the absorbed dose corresponds to 59.83%. The axial dose profiles were recorded at 1 cm depth, and presented dose values in the plateau region of 98.02 ± 1.02 % for the X axis and 98.22 ± 1.44 % for the Y axis, considering the maximum dose value. In radiotherapy procedures, small-sized fields can modify the dose deposition profiles and this understanding should be considered. The obtained profiles allowed to verify disturbances present in the exposures, considering the dosimetry of small fields and the impacts on the planning of local dose deposition. (Author)