iaea human health series publications - SEDIM

iopsies are performed, a sink is of higher priority. Cleaning supplies for the compression paddles and tabletopshould be easily accessible and used frequently (after each client). Check with the manufacturer of themammography unit for recommended cleaning products and instructions specific to the unit.I.7.ELECTRICAL SERVICES REQUIREDMost current digital mammography units operate from standard single phase AC circuits with a power drawof around 10 kVA instantaneous (for up to 6 s) and a standby draw of 1.5 kVA. Most units are configurable toregional power and operate on either 50 or 60 Hz. A mains isolator switch or circuit breaker fused at 25 A for200–240V is normally required in the room. Additional line voltage receptacles for the acquisition workstation maybe required if the workstation is not directly connected to the mammography unit.I.8.ENVIRONMENTAL SERVICES REQUIREDSince most mammography rooms are very small and the door remains closed during the procedure, there areoften problems with environmental control. The mammography unit dissipates a considerable amount of heat, withthe maximum specified being 3 kW. Often there is also a computer and monitor producing another 400 W. This heatshould be considered in addition to that from the two people occupying the room for the entire day.Digital detectors are very sensitive to temperature extremes, sometimes more so when they are notoperational. Any detector that has a cooling fluid cannot tolerate freezing temperatures and may be completelydestroyed if the coolant freezes inside the detector. For selenium based systems, if the room or detector temperaturerises above 38°C, the detector may degrade irreversibly. If the room temperature drops below or rises above ‘thecomfort zone’ (16–28°C), a significant length of time may be required until the operation of the detector stabilizes.Cooling units require that the room temperature be in the comfort zone, and may not be able to maintain systemstability if that limit is exceeded. Always check carefully with the manufacturer for the exact requirements, asreplacement detectors are expensive and are not covered by the warranty if environmental condition requirementshave been exceeded.There is a requirement for fresh make-up air as well as a cold-air return within the room. The fresh-air diffusershould not be directly in the centre of the room (over the client), as it is sometimes very uncomfortable to have airblown on a bare back and shoulders. The room should have independent heat and air conditioning control. Thereshould be adequate humidity regulation so that there is reduced static build-up in the room. This is both for clientcomfort (to reduce contact static discharge) and to prevent static attraction of dust to the compression paddles andstatic artefacts on the films.I.9.GENERAL INSTALLATIONAs dedicated digital mammography systems are often of freestanding design, it should be verified that theentire system is properly installed in the examination room and is stable. Floor loading for the gantry can be up to400 kg, concentrated on the area of the base plate of 0.33 m 2 . The control unit (up to 150 kg) should be level, andthere should be convenient access for service and maintenance. There should be no obstruction that hinders therange of mechanical motions provided by the system. It should be ensured that the mechanical stops and magneticlocks are properly set and adjusted to prevent accidental motion or collision against other mechanical parts or theclient.I.10. RADIATION SHIELDING AND REGULATORY APPROVALSThe International Basic Safety Standards for the Protection against Ionizing Radiation and for the Safety ofRadiation Sources (the BSS) [72] establish the requirement that all practices using ionizing radiation should beauthorized. The radiology installations require, accordingly, authorization granted by the applicable regulatory138