Optimization of Radiation Dose in CT Chest Examination

Abstract

Computed tomography (CT) examinations can involve relatively high doses to patients. The doses can often approach or exceed levels known with certainty to increase the probability of cancer. Therefore, optimisation of patient dose is crucial. The objectives of this study were to: (i) measure the radiation dose for patient during 64 slices CT Chest scan, (ii) optimize the radiation dose and (iii) estimate the lifetime attributable to risk of cancer. A total of 50 patient divided into two groups one as control group (A) (38 patients) and optimization group (B) (12 patients).Group A were performed with the own department protocol using 64 slice CT Scan (Toshiba, Aquilion) in Al-Amal national Hospital, Khartoum North, and group (B) the optimized group were performed by the optimized technique increasing the pitch factor. Data were collected to study the effects of patient-related parameters, exposure-related parameters. The organ dose conversion factor f (organ, z) was obtained from the NRPB datasets (NRPB-SR279) based on the Monte Carlo simulations. The mean CTDIvol was 21.17 mGy and DLP was 839 mGy. cm for group A and CTDI vol was 8.3 mGy and DLP was 239.67 in group (B). The effective dose for group A was 14.6 mSv and for group B was 5.7 mSv. The probability of overall cancer risk was estimated to be 267 per million The relative high dose in group( A) may be due to many factors such as operators and practitioners are insufficiently educated in newly emerging technology, or patient related factors. The mean organ doses in this study were mostly comparable (group B) to and slightly higher (group A) than reported values from the developed countries. Proper justification of examinations, use of the appropriate technical parameters during examinations, proper quality control, and application of diagnostic reference levels of dose as appropriate would reduce the patient radiation during CT examination