The calculated scattered radiation dose to persons in the proximitiy of patients receiving a chest x-ray from mobile xray units assuming the following typical operating conditions
- 85 kVp, 2 mAs, 3mm Al filtration
- 180 cm FFD
- 35cm x 43cm CR image receptor
- Proximity of the nearest person on either side of patient is around 1 metre or more,and the primary beam is completely intercepted by the receptor and not directed towards other patients or staff.
Under these conditions the entrance exposure (air kerma) to the patient is calculated to be 52 micrograys, and the scattered radiation at one metre to either side around 0.2 micrograys. To place this in perspective it should be borne in mind that the dose from natural background radiation (to which everyone is exposed) is of the order of 2400 micrograys per year; the scattered radiation from a mobile CXR at a distance of 1 metre is therefore less than that received from one hour of natural background radiation. This is an extremely small radiation exposure and the resultant risk to staff and patients is negligible.
These calculations were performed by the
Chief Medical Scientist at Flinders Medical Centre
Radiation Safety Officer
Division of Medical Imaging
Further reading
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