Authored By:
Little et al.This paper reviewed studies on cancer risk from medical diagnostic radiation exposure in utero, and postnatal stages of life where radiation quantitative dose estimates were not available. The type of procedure (e.g. fluoroscopy, CT scan, X-ray etc.) gives a general indication of the likely dose involved but this is not as informative as studies that include data on the actual doses received. The literature search identified 89 eligible studies that were included in this review and meta-analyses were conducted. This review found multiple studies that yielded statistically significant excess cancer risks due to in utero and postnatal exposure to medical diagnostic radiation. Significantly higher risk estimates were found for leukaemia, lymphoma, central nervous system (CNS) tumours and any other cancer in the meta-analysis for in utero exposure. This is mainly due to earlier studies which found more significant excess risk than later studies. The reduced excess risk in later studies could be explained by the progressive decrease in foetal dose per X-ray examination due to advances in radiographic technology. For postnatal exposure, significant excess risks were more apparent in later studies, particularly CT scan studies. The postnatal meta-analysis found statistically significant excess risks for leukaemia, CNS tumours and any other cancer outcomes. This data strengthens the evidence for a carcinogenic effect of low dose radiation exposure in utero. However, the interpretation of the postnatal exposure findings is more difficult due to the possibilities of reverse causation (i.e. conditions predisposing to cancer lead to an increase of radiation imaging) biasing the results. Subsequently, this reduces the strength of a causal interpretation for postnatal exposure.
Published In:
Science of the Total EnvironmentIn Australia, the system for radiological protection draws on international best practice, particularly, the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA). Special concern in relation to radiation protection is afforded to children, and women of child-bearing age. Most diagnostic radiology procedures pose little risk to the mother or foetus. However, interventional radiology procedures, and CT scans of the abdomen or pelvis may result in an elevated foetal dose, and an increased risk of cancer. With the continuing advancement of the use of ionising radiation in medicine, it is important that safety guidance represents contemporary best practice. The Code for Radiation Protection in Medical Exposure (2019) (RPS C-5) sets out the Australian requirements for the protection of patients, including pregnant women and children, relating to their exposure to ionising radiation. It is ARPANSA’s goal to ensure that the highest standard of protection is made available through the implementation of the relevant Codes and Safety Guides. These safety materials give practitioners in diagnostic and interventional radiology a best practice approach to their day-to-day clinical work. While the (Little et al) study’s meta-analysis supports a statistically significant increase in cancer risk, the increase is very small and the risks should be assessed against the benefits of having the procedure. ARPANSA advises parents concerned about their children’s exposure from radiological procedures to talk to the doctor requesting the radiological procedure. The child’s doctor and the staff at the radiology facility should work together on which tests are required and evaluate the risks and benefits in each child’s individual circumstances. If there are still questions at the radiology facility, these can be raised with the radiology team during the consent process before the imaging proceeds.
