RADIATION DOSE TO PATIENTS UNDERGOING CHEST RADIOGRAPH AND BRAIN CT SCAN IN THE RADIOLOGY DEPARTMENT OF FEDERAL MEDICAL CENTRE KATSINA

This study presents a comparative analysis of radiation dose indices across two diagnostic modalities: conventional projection radiography and computed tomography (CT), utilizing data from two distinct patient cohorts (N=20 each). The primary objective was to evaluate the relationship between technical exposure parameters—specifically tube voltage (kVp), tube current-time product (mAs), and exposure time—and the resulting radiation dose markers, including estimated dose for radiography and CTDIvol and DLP for CT. For the radiography cohort, patient ages ranged from 29 to 55 years. Analysis revealed that dose levels were highly sensitive to fluctuations in kVp (70–76 kVp) and mAs (9–12 mAs), with estimated doses remaining within a low-level safety margin of 0.17 to 0.22 mGy. The findings suggest a high level of protocol standardization in conventional imaging, where adjustments are minimal and primarily driven by anatomical requirements while maintaining a narrow dose variance of only 0.05 mGy. In contrast, the CT cohort (ages 29–54) demonstrated the implementation of a fixed-voltage protocol (120 kVp), with dose modulation achieved exclusively through mAs variations (225–265 mAs). This resulted in CTDIvol values ranging from 53 to 61 mGy and DLP values between 910 and 1040 mGy·cm. The direct correlation between mAs and dose indices in CT highlights the clinical significance of current modulation as a tool for dose optimization. While CT doses are naturally orders of magnitude higher than those in projection radiography, both modalities exhibited a trend toward precision and consistency. The results underscore the importance of technical parameter selection in adhering to the ALARA (As Low As Reasonably Achievable) principle. The uniformity in kVp for CT scans suggests that peak energy is often standardized for specific diagnostic tasks, while mAs serves as the primary variable for adjusting to individual patient characteristics. Conversely, radiography protocols involve more frequent adjustments to both voltage and current, though the absolute dose variation remains small.