The Program of Quality Assurance (QA program) in Ionizing Radiation Therapy (RT) addresses the most important problems of assuring the quality of RT utilization in the treatment of patients with neoplasm. In this context, the RT value grows considerably, hence the implementation of QA program is of great importance. This study concentrates on a detailed description of the QA program as concerns the activity involving RT devices applied in the RT departments (rooms) of public medical/sanitary institutions, science research institutions etc., where RT is employed using technogenic sources and ionizing radiation generators. In the study, annual statistics reports about the activity of the RT, and data of Cancer Registry of the Oncologic Institute of the Republic of Moldova were analyzed. The work also included an in-depth description of the personnel categories involved in QA program, possible errors in radiotherapy, the responsibilities of the medical physicist in this program, importance of source calibration, the impact of the quality control in QA program, the role of topometric training, the interaction between the medical and technical personnel and the patient. Optimization of RT is very important and necessary in the Republic of Moldova. QA program incontestable contributes to reducing specialist’s errors in planning correct treatment. It dictates the need of team work, duty of medical physicist, the influence of quality control of profile installations etc.