[Accidental exposure to X-ray from a diffractometer].

The patients's clinical pictures, characterized by an erythema preceding the skin manifestations, their aspect and the occupational histories, made the diagnosis of a radiation accident possible before its dosimetric identification. Doses evaluations using thermoluminescence dosimeters and ionizing chambers correlated well with the clinical estimations. The immediate cause of the accident was poor maintenance of the device that caused its back window to be permanently open, but lack of adequate information on the biological effects of ionizing radiation and on the correct operational procedures were contributory facts. The description of this accident is relevant in virtue of the misconception that such equipment have "virtually no occupational risk". The patients's medical evolutions have had a favorable course, specially because the low energy of the X-ray and its low penetrating capacity. This accident highlights the need for the adequate training of workers on the handling of radiation devices.