Evaluation of personal doses associated with the use of mobile X-rays in a Brazilian hospital.

In Brazilian public hospitals, the number of patients needing assistance is often much greater than the capacity of the hospital. In such situations, medical procedures are performed as quickly as possible, and mobile X-ray equipment is used intensively. This equipment is used for several types of examination, in different areas of the hospital. During the examination procedure, apart from the radiology technicians involved, there are always other people in the room who are also exposed to the radiation scattered by the patient. The objective of this study was to determine the exposure, due to the use of mobile X-ray equipment, of hospital personnel, divided into two categories named 'monitored' and 'non-monitored'. Evaluation of 413 radiographies was performed, the vast majority of them being chest examinations (75 %). During the procedures, specific information was collected to allow measurement in simulated situations. Air kerma rates were measured at different distances from the mobile X-ray equipment using an ionisation chamber and an acrylic phantom with dimensions of 30×30×15 cm(3). From the results, it was possible to estimate the personal dose equivalent received by the individuals in the room during the procedure and to determine the dose maps associated with the use of the mobile X-ray equipment. The results obtained in this study were in accordance with dose limits, but some observed situations were considered critical.