OBJECTIVE: To assess the non-radiologist physicians' knowledge on the use of ionizing radiation in imaging. MATERIALS AND METHODS: Cross-sectional study utilizing an anonymous questionnaire responded by physicians in clinical and surgical specialties, divided into two parts as follows: one including questions about the physicians' characteristics, frequency of imaging studies requests and participation in professional updating events, and another part including multiple choice questions approaching general knowledge about radiation, optimization principles and radioprotection. RESULTS: From a total of 309 questionnaires, 120 (38.8%) were responded, 50% by physicians in surgical specialties and 50% in clinical specialties; respectively 45% and 2.5% of physicians responded that magnetic resonance imaging and ultrasonography use ionizing radiation. Overall, the average grade was higher for surgical specialists with no significant difference, except for the question about exposure in pregnant women (p = 0.047). Physicians who are professionally updated, particularly those attending clinical meetings (p = 0.050) and participating in teaching activities (p = 0.047), showed statistically superior knowledge about ionizing radiation as compared with others. CONCLUSION: The non-radiologist physicians' knowledge is heterogeneous and in some points needs to be improved. Multidisciplinary clinical meetings and teaching activities are important ways to disseminate information on the subject.

Keywords: Ionizing radiation; Knowledge; Physicians; Imaging diagnosis; Radiation protection; Questionnaire.