Assessment of Typical (DRL) Values, Size-Specific Dose Estimates, Organ Doses and Effective Doses of Adult Patients undergoing Computed Tomography Examinations in a University Hospital in Brazzaville, Congo Republic.

The present paper aimed to assess typical values, size specific dose estimates, organ doses and effective doses of adult patients undergoing computed tomography (CT) examinations in a university hospital in Brazzaville, Congo Republic. The study involved 308 adult patients of which 51% were female patients and 49% were male patients. The age varied from 17 to 96 years with an overall average of 55 years. Median values of the distribution of dose-length product (DLP) and volume CT dose index (CTDIvol) for each CT examination type were defined as typical values in agreement with the International Commission of Radiological Protection (ICRP) publication 135. Size-Specific Dose Estimates (SSDE) were calculated using the American Association of Physicists in Medicine (AAPM) methodology. Organ doses were computed following a methodology that uses dose coefficients and CTDIvol. Effective doses were derived using the calculated organ dose values and tissue weighting factors given in ICRP publication 103. Overall typical CTDIvol values determined were 57 mGy, 2.7 mGy, 3.2 mGy and 3.2 mGy for head, chest, abdomen-pelvis (AP), and chest-abdomen-pelvis (CAP) scans, respectively. Overall typical DLP values determined were 1172.2 mGy cm, 158.3 mGy cm, 163.2 mGy cm, and 203.6 mGy cm for head, chest, AP and CAP scans, respectively. The overall SSDE median values were 4.3 mGy, 4.5 mGy and 4.7 mGy for chest, AP and CAP scans, respectively. Typical values, size-specific dose estimates, organ doses and effective doses determined for female patients were greater than those determined for male patients. The study also showed that the CAP and AP scans were associated with the highest effective dose (2.4 mSv and 2.2 mSv, respectively) while the head scan was associated with the lowest effective dose (1.3 mSv). The overall dose values determined in this study were significantly lower than those reported in selected studies reported in the literature.