Maternal and Foetal Radiation Dosage during Obstetric Radiographic Examinations

Tissue equivalent phantoms have been used to estimate the dose to various parts of the foetus and to the maternal ovaries during obstetric radiography at 100 to 120 kVp. These phantoms were made by taking plaster casts of pregnant women at term. An estimate has been made, for each projection, of the dose delivered to the foetal gonads in the average case. An estimate has also been made of the value of the dose averaged over the whole foetus, for each projection. The inlet projection is found to give rise to by far the highest radiation levels. A short investigation was made of the various factors which influence the doses delivered in radiography and some recommendations are given on methods of keeping the doses to a minimum.