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Radiological Protection of Patients |
Pregnancy and radiation protection in DXA
Although the increased risks to both mother and foetus are small (see below) they are not zero. Thus the policy followed should be based on that for radiological examination of women of childbearing age that is generally followed in the region. Central to this is the policy that justification of the scan must take account of the presence of and the risk to the foetus. The clinical benefits of the DXA scan must clearly outweigh the risks, and (perhaps more significantly) the psychological of worry about radiation risks. No single answer can be given and the justification process must be undertaken for each patient. The value of deferring the examination should be considered, as it is seldom urgent. Alternative methods, not involving ionizing radiation, of obtaining the information should be assessed. The possibility that foetal tissue may overlie the area of interest in, for example, a lumbar spine DXA and introduce errors may confuse the measurement. In this situation, there might be little or no benefit from the scan, and hence it would not be justified. Finally, in pregnancy, the option of DXA of the heel should be considered.
Should a woman be inadvertently irradiated during pregnancy, she should be counselled by an experienced person expert in the area. The doses and risks involved are generally very low and sufficiently small that consideration of a termination would not arise. It is important to establish the pregnancy status of a woman of childbearing age prior to the scan, so that the justification process includes consideration of the risks to the foetus. For extensive coverage of pregnancy, Details ».
There are no reports as yet of the dose to the foetus from newer generations of DXA systems. However, they are bound to be less than the entrance surface dose (ESD) to the mother. This is dependent on both the technology used and the technique employed. However, it is generally well under 1 mGy, which is the dose limit for the foetus. If the uterus lies outside the irradiated area the foetal dose will be less than this, whereas if the uterus lies within the irradiated area, the foetal dose is expected to be about half of the ESD.
If DXA scan has been performed, the assumed foetal dose is too low to lead to effects such as organ malformation or a significant loss of IQ [ICRP 84]. It is small by comparison to doses from common radiographic examinations of the abdominal area of the mother. All radiation doses carry a finite risk of inducing cancer or genetic disorders in the foetus. The DXA doses are such that these risks are small by comparison with the natural incidence of these conditions. Details ».
See question 7 in the Staff Radiation Protection section.