Evaluation of radiation risks during CT brain procedures for adults

The purpose of this study is to evaluate the patients’ radiation dose in three different modalities of CT scanners (64, 16 and 2 slices) and the biological effects during CT brain examinations.

A total of 60 patients were examined in three different hospitals in Morocco. The data were collected from CT Brain examinations at of 20 CT scans per hospital. For each examination, we have reported CT acquisition parameters including the number of series, use of contrast medium; tube kV, tube current and rotation time, slice thickness as well as the displayed CT dose index (CTDI_vol) and the Dose Length Product (DLP). Cancer and biological heredity risks were estimated using the International Commission on Radiological Protection (ICRP) conversion factors.

The average dose values for CT brain for 2 slices was 305 ± 112 mGy.cm. The mean dose value for 16 slices was 716 ± 179 mGy.cm, while the average dose for 64 slices was 1136 ± 708 mGy.cm. The patient cancer risks per procedure ranged between 4 and 13 per 10⁵ CT procedures. This risk is 4, 8 and 13 per 10⁵ CT procedures for 2 slices, 16 slices and 64 slices respectively. The patient heredity risks varied between 1 and 5 per million CT procedures. It is 1, 3 and 5 for 2 slices, 16 slices and 64 slices respectively.

Dual slice scanner delivered the least effective dose while 16 and 64 slice scanners delivered the highest effective dose. The dose values of this study were comparable to the international reference levels of CT examination. CT dose optimization protocol is not implemented in the Moroccan hospitals. These values could be used as our hospital's Dose Reference Levels (DRL) until a more detailed study survey can be conducted in Morocco for the establishment of the country's reference levels.