Regulation No. 0-34, on radiation protection from medical 300 kVp X-rays

The regulation applies to any X-ray room and machine in Bulgaria, and covers design, construction, instrumentation, and operation requirements. A glossary of concepts, terms, dimensions, and units used is given. The maximum permissible exposures and exposure rates specified comply with radiation safety standards established for the country. An occupancy factor for a particular type of room and a X-ray unit utilization factor are introduced. Utilization time per working shift is of 210 min for therapeutic units and of 150 min for diagnostic units. Requirements are listed relating the room lay-out and X-ray unit positioning for therapy, fluoroscopy, subscreen films, and films. Any type of X-ray unit has to be provided with shielding constructional parts and additional protective appliances, including: protective jacket, interchangeable tube set or limiting diaphragms, beam outlet shutter, control board alarm system, radiation timer, centering device, protective gloves and aprons, radiation filters, protective shields, chairs, distinctors, adaptation eyeglasses, protective cabins, casette holders. The safety rules for work with each particular type of X-ray unit are given in a separate chapter. Protection monitoring requirements are specified with regard to instruments, techniques, and procedures to be used. Documents to be available at each X-ray room or department are listed, such as the licence issued, a radiation safety plan, staff certificates, personnel-monitoring and operational data records, maintenance revision books. (G.G.)