Clinical Electron Beam Dosimetry Investigations

Abstract

Radiotherapy is one of the most effective treatment modalities for cancer, together with surgery and chemotherapy. The aims of curative radiation treatment are to increase tumour control probability (TCP) and minimize normal tissue complication probability (NTCP). This study considers the parameter which can affect the absorbed dose of electron beam in linear accelerator. The linac (ELEKTA Model) in Radiation and Isotopes center Khartoum (RICK) being used to treat the tumor cancer, with multi energy beams, of photon 6MV and electron that ranges from 6 MeV up to 15 MeV. The linac device is a highly efficient but sensitive to temperature and pressure. The absorbed dose was measured in water for electron beam energies (15, 9, and 6 MeV). Measurements were performed every day for 4 weeks. At 2 hours interval per day. The doses were measured using PPC 05 and FCC65 ion chambers and water phantom. The deviation between the absorbed dose to water obtained and the reference dose from the result obtained is 0.8%-1.1%. This value is within the recommendation of IAEA TRS-398 protocol. Which accept absorbed dose to water in depth of maximum within 2.5% From the result obtained, it can be noticed that there is no deviation between the doses, due to the variations of temperature and pressure. This will confirm the stability of linac system during the day, and the importance having good air conditions system in the linac room.