The use of afterloading equipment for brachytherapy purposes may expose patients to danger if the equipment fails to deliver the required dose to the patient, or if the equipment design does not satisfy standards of electrical and mechanical safety. The equipment may also cause danger to persons in the vicinity if the equipment itself fails to contain the radioactive source(s) adequately within the storage container(s) and/or if there are inadequacies in the design of the treatment room.This Particular Standard establishes requirements to be complied with by manufacturers in the design and construction of afterloading equipment for use in temporary brachytherapy procedures. Its purpose is to identify those features of design that are regarded, at the present time, as essential for the safe operation of such equipment. It places limits on the degradation of equipment performance beyond which it can be presumed that a fault condition exists and where an interlock then operates to return the radioactive source(s) to the storage container(s) and afterwards to prevent continued operation of the equipment.