Serviço de física médica
: contribuições para a garantia da qualidade em radioterapia

  • Ana Catarina Lopes Ramos (Student)

Student thesis: Master's Thesis


This internship report is based on the curricular internship carried out during four months at the Instituto Português de Oncologia do Porto Francisco Gentil, E.P.E. (IPOP), in the Medical Physics service, in order to obtain a Masters degree as part of the Master's in Biomedical Engineering at the Universidade Católica Portuguesa do Porto. The report aimed to present a theoretical framework in the area of Radiotherapy and Medical Physics and explain the main activities developed as a trainee. Radiotherapy is defined as a medical specialty focused on cancer treatment through the use of ionizing radiation to treat almost all types of cancer. Medical physics is a specialty of physics that focuses on the application of physical principles and techniques in the field of medicine. The activities reported in the work are related to the quality control of linear accelerators and the main parameters evaluated: mechanical tests, dose profiles, homogeneity and symmetry, quality index, dose rate, LINACHEK and verification of parameters of photon beams of energies 6MV and 15 MV and electrons of energies 6MeV, 9MeV and 12 MeV in the Varian DHX model equipment, according to the TRS 398 protocol. After analysing the results, it was found that all parameters were in accordance with the established tolerances and the accelerator would be ready for use. The second practical work consisted of quality control of the patient treatment plans, using two different methods: through EPID or the ionization chamber array. Dosimetry of radiochromic films consisted of determining calibration curves using energies of 6MeV and 9MeV, and irradiating GAFChromic EBT-3 films in a 10x10cm field with 100cm SSD and then scanning and determining the optical densities, using DoseLab-Pro software and finally determining the dose present in the radiosensitive films. Finally, in the last practical work, 34 different types of dressings were analysed, exposed to energies of 6MeV and 9MeV, evaluating and quantifying the dose and the effect it could have on the patient's skin. It is concluded that unsaturated dressings have a higher attenuation than saturated ones, and that the dose deposited in the radiosensitive film is higher in the presence of saturated dressings.
Date of Award4 Sept 2023
Original languagePortuguese
Awarding Institution
  • Universidade Católica Portuguesa
SupervisorJoana Borges Lencart e Silva (Supervisor)


  • Radiotherapy
  • Linear accelerator
  • Quality assurance
  • GAFChromic EBT-3


  • Mestrado em Engenharia Biomédica

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