In diagnostic radiology examinations there is a benefit that the patient derives from the resulting diagnosis. Given that so many examinations are performed each year, it is inevitable that there will be occasions when an examination(s) may be inadvertently performed on pregnant patients or occasionally it may become clinically necessary to perform an examination(s) on a pregnant patient. In all these circumstances it is necessary to request an estimation of the foetal dose and risk. We initiated a study to investigate fetal doses from different countries. Exposure techniques on 367 foetuses from 414 examinations were collected and investigated. The FetDoseV4 program was used for all dose and risk estimations. The radiation doses received by the 367 foetuses ranges: <0.001–21.9？mGy depending on examination and technique. The associated probability of induced hereditary effect ranges: <1 in 200000000 ( ) to 1 in 10000 ( ) and the risk of childhood cancer ranges <1 in 12500000 ( ) to 1 in 500 ( ). The data indicates that foetal doses from properly conducted diagnostic radiology examinations will not result in any deterministic effect and a negligible risk of causing radiation induced hereditary effect in the descendants of the unborn child. 1. Introduction In diagnostic radiology examinations, there is a benefit that the patient derives from the resulting diagnosis, provided that they are fully justified. However, given that so many examinations are performed each year, it is inevitable that there will be occasions when an examination will be performed on a woman who subsequently discovers that she was pregnant at the time of her examination(s). It may also occasionally become clinically necessary to perform a radiological examination(s) on a woman who is known to be pregnant. In the later case, there must be rigorous justification of the examination and the procedure itself must be optimized to minimise the foetal dose [1–3]. In order to avoid the former, some special rules have been developed to apply to the exposure of potentially pregnant women (who are or who may be pregnant) in which radiological examinations of such women are restricted to a certain period following menstruation [4–7]. For the protection of the foetus from occupational exposure of the pregnant worker, the International Commission on Radiological Protection (ICRP) [1, 2] considers that if a female worker has declared (i.e., notified her employer) that she is pregnant, additional controls have to be considered to protect the embryo/foetus. It is the Commission’s policy that the
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