Computed Tomography Organ dose determination using ImPACT simulation software: Our findings in South-West Nigeria

Objectives: The aim of this study was to estimate mean organ dose using the imPACT software, and to determine if dose vary significantly for similar organ among the 7 Computed Tomography (CT) units and to compare and correlate our findings with international studies with similar software. Methods: Seven CT units denoted as A-G was randomly selected. An imPACT Patient Dosimetry Calculator Software was used to determine organ dose to the head, chest, abdomen and pelvic region from 210 patients' CT parameters retrieved from the CT monitor. Data analysis was done using SPSS 16.0 (SPSS Inc, Chicago, IL, USA). Results: The mean dose to organs in the head (brain and eye lens) was 27.87±9.58 and 55.27±22.34mGy; chest (lungs, breast, thyroid and heart) was 30.63±8.21, 26.41±6.76, 10.21±7.00 and 29.93±9.65mGy; Abdomen (stomach and liver) was 34±12.8 and 33.05±9.93mGy and Pelvis (bladder and uterus) was 32.44±13.8 and 28.97±7.14mGy respectively. Similar organ show statistically significant difference: for brain (p<0.001), eye lens (p=0.001), lungs (p<0.001), breast (p<0.001), thyroid (p=0.008), heart (p<0.001), stomach (p<0.001), liver (p=0.001), bladder (p<0.001) and uterus (p=0.002) among the 7 CT units. There was no correlation in organ dose for this study and those of Tanzania, Turkey, Japan and Thailand. Conclusion: Significant differences exist in similar organ doses among the 7 CT units in Lagos indicating that there was lack of harmonization in CT protocols.