[en] This dissertation aimed to identify the minimum clinical information necessary for medical justification in the request of imaging exams with the use of ionizing radiation. Providing adequate clinical information in order to perform imaging tests can improve the imaging process, increase the accuracy with which medical radiologists interpret images, and reduce the number of diagnoses lost. The justification of the imaging tests that require ionizing radiation is mandatory by Federal Ordinance No. 453 of 1998. It should be a communication channel between the assisting teams and radiology, if it were used focusing on the patient - adding value and reducing time to diagnosis and treatment. Many factors may influence the entire imaging cycle - from the clinical evaluation by the attending physician, the need for the imaging exam, the execution of the images by the radiologist, the evaluation of the images by the radiologist and the delivery of the results in the medical record of the patient. The study sought to identify the factors that are influenced by the provision of clinical information throughout the process of the imaging cycle through the theory of Dynamic Systems. The quality of the clinical information provided in the context of a public teaching hospital was analyzed, as well as the influence of the clinical information on the choice of imaging protocols, the quality of the results and the degree of satisfaction of the radiologist with the result of the examination. The exploratory descriptive field study carried out a qualitative research in four stages, using historical data analysis, a questionnaire and a group focused as instruments of data collection. Among the main results, it was possible to construct a Causal Loop Diagram and to identify factors of influence in the provision of clinical information such as the knowledge of the importance of justification by the requesting physician; the time of release of the report and the need for complementary examinations. Among the minimum clinical information required, the main ones were the presence of a diagnostic hypothesis with a question to be answered; signs and symptoms of the patient and anatomical changes due to patent surgery. (author)