Medical Radiation Examinations Affect Women Of Child Bearing Age

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Pregnant women should not undergo some types of medical examination that involve high doses of radiation to the foetus because of the small increased risk of causing childhood cancer, according to guidance developed by the Health Protection Agency, The Royal College of Radiologists and the College of Radiographers.

The guidance published today recommends that pregnant women should not be given ionising radiation examinations in which the foetus receives a dose of more than a few milligrays1 (mGy) - for example CT scans of the lower abdomen. It is recognised, however, that such examinations may sometimes be clinically justified by an overriding benefit to the health of the mother. If such examinations have taken place, the risk of causing childhood cancer would still be relatively small and termination of pregnancy would not be considered necessary.

The guidance stresses that most medical examinations that use ionising radiation - which include X-rays, dental X-rays, CT scans and nuclear medicine scans - involve foetal doses of less than, and often very much less than, 1 mGy. For these examinations the associated risks of childhood cancer are very low (less than 1 in 10,000) and much lower than the natural rate of childhood cancer (1 in 500). The guidance also indicates that the foetal radiation doses from all current medical examinations are too small to cause foetal death, malformation, retarded growth or impair the mental development of the unborn child.

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The report updates 1998 advice by the former National Radiological Protection Board, now part of the Health Protection Agency (HPA), The Royal College of Radiologists and the College of Radiographers. It is aimed at hospital staff working in radiology and nuclear medicine departments and includes clear practical guidance on how to avoid inadvertent exposures of pregnant patients that could lead to significant risks for the unborn child.

Even though the risk to the unborn child is much lower in the first few weeks of pregnancy - when a woman may not realise she is pregnant - the guidance recommends that certain very high dose examinations where the foetal embryo could receive a dose of more than 10 mGy should not be carried out on early unrecognised pregnancies. One way of preventing this is to restrict such examinations to the first 10 days of the menstrual cycle, when the woman is unlikely to have conceived.

Roger Cox, Director of the HPA's Centre for Radiation, Chemical and Environmental Hazards said: "While most medical examinations using ionising radiation are considered extremely safe, a small number of procedures could result in the foetus receiving relatively high doses of radiation. The HPA's advice gives clear clinical guidance on how best to protect pregnant women and their unborn child during these medical examinations."

Maria Murray, spokeswoman for the College of Radiographers, said: "Diagnostic Radiographers are pivotal to the safe use of ionising radiations in diagnostic imaging services. This publication provides significant updated scientific knowledge and practical guidance and is essential reading for all Radiographers practising in the UK."

Dr Bob Bury, spokesman for The Royal College of Radiologists, added: "It is important to prevent inadvertent exposure of the foetus and have straightforward guidance for staff booking and carrying out examinations. It is also important to keep the risks of radiation in proportion, and give clear advice to patients if inadvertent exposures do occur. The RCR supports this revised guidance, which helps hospital staff responsible for the protection of patients and the unborn child."

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