Radiation protection of pregnant women during DXA

» Can DXA scan be performed on a pregnant woman?

Although the increased risks to both mother and foetus are small they are not zero. The policy to be 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. 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.

» How should one deal with possible pregnancy in DXA BMD measurement?

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. 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. 

» What are the typical foetal doses in a DXA scan? 

So far, there are no reports 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. 

» What are the risks to the foetus if a DXA scan is performed on a pregnant woman?

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. 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. 

Read more:

  • INTERNATIONAL COMISSION ON RADIOLOGICAL PROTECTION, Pregnancy and Medical Radiation, Annals of the ICRP, Publication 84, Pergamon Press, Oxford (2000).