Working rules are essential to ensure that all types of x-ray analysis (XRA) equipment are used with a high standard of safety.
Section 6 of the Code of Practice for Protection Against Ionizing Radiation Emitted from X-ray Analysis Equipment (NHMRC 1984), details the main procedures and check lists which are appropriate for both fully and partially enclosed XRA units. The Code specifies the following working rules which are common to all XRA machines:
- Exposure to the primary x-ray beam must be avoided at all times.
- The unit must not be operated if any of the warning lights are not operational.
- No x-ray tube may be energised:
- while outside its protective tube housing, or
- with an unshielded aperture in the tube head or protective barrier
- No sample, collimator or analysing crystal shall be changed or adjusted whilst a primary x-ray beam passes through that collimator or is incident on that sample or crystal unless:
- the sample, collimator or crystal, during and after the change or adjustment is within a shielded enclosure, and
- the change or adjustment is performed by remote means from outside the enclosure
- Immediate measures must be taken to remove potentially hazardous situations arising from x-ray beams that may be emitted due to an equipment defect, misalignment or any other reason.
- Additional working rules, specific for each XRA unit must, where necessary, be documented to ensure the safe operation of the unit.
- XRA equipment must not be operated by inexperienced persons unless under the direct supervision of an experienced operator.
- Visual alignments or adjustments must not be carried out while the x-ray tube is energised, unless a viewing system is used which is shielded or designed to prevent exposure of the eye or other parts of the body to the primary beam.
- XRA equipment is not to be operated with interlocks inactivated without prior approval from the statutory authority, which in WA is the Radiological Council.
- If prior approval has been granted then:
- The number of people who carry out the alignment or alterations while the x-ray tube is energised must be restricted to the minimum necessary to carry out the operation safely.
- An experienced person not engaged in the operation must observe the procedure and warn each operator of any action that might lead to an exposure.
- Physical barriers and a warning sign at each entrance must prevent access of non-essential personnel.
- Users of x-ray analysis machines must hold a x-ray analysis users' licence or be under the supervision of a licence holder.
- Accidents and incidents must be reported to Safety and Health.
- The School Radiation Safety Officer.
- Service may only be carried out by a service technician with a suitable Radiological Council licence.