Foetal dose estimation in the medical exposure of pregnant women

The research is a retrospective study considering female patients of adolescent age and older. A total of 90 patients were involved with their mean age of 32.2 years ranging from 19.0-50.0 years old. The research considered examinations that had the uterus in the field of exposure (abdomen, lumbar spine, pelvis and hip joint) and the uterus outside the field of exposure (chest and thoracic spine). The FetDose software was used to estimate the foetal doses and the risks associated with it to each of the assumed foetuses. Combining doses from all the three hospitals, the mean dose for AP pelvis was approximately 1.36 mGy and the AP abdomen was 0.57 mGy for 8-15 weeks of pregnancy. Risk factors per mGy for severe mental retardation and loss of IQ points associated with these mean foetal doses were 5.84 x 10-4 and 4.07 x 10-2 for AP pelvis and 2.46 x 10-4 and 1.72 X 10-2 for AP abdomen respectively assuming there is no threshold for the occurrence of these effects. Risk of hereditary effects, fatal leukaemia and fatal cancer per mGy were estimated as 3.26 x 10-5, 1.70 X 10-5 and 2.38 x 10-5 for AP pelvis and 1.37 x 10-5, 7.15 x 10-6 and 1.00 x 10-5 for AP abdomen examinations respectively. The radiation risk due to X-ray exposures to the foetus from plain radiographic examinations is negligible for all the examinations studied except the AP pelvis examination with mean foetal dose much higher than that published in the National Radiological Protection Board report of 1998 (au).