Assessing the Status of Quality Control Parameters of Four Computed Tomography Scanners in Ibadan

Background: Quality control (QC) of computed tomography (CT) scanners is important to evaluate succinctly quality image and radiation dose obtainable in a clinical environment. The aim of this study was to evaluate the quality of images generated by CT scanners used at some diagnostic facilities in Ibadan, Nigeria.

Materials and Methods: A cross sectional design was employed in this study, four centers were studied, one government hospital and three private hospitals. The head CT phantom was used to verify the accomplishment of the CT scanners performance to the international quality requirements. Regions of interest were selected at the center of the image and at the periphery to obtain results for the CT number for water test, uniformity test, noise, and artifact test.

Results: The mean CT number for water across the centers ranged from –0.12 HU to –2.2 HU which were within ±3 HU recommended by the equipment manufacturer. Values of standard deviation of the mean CT number ranged from 2.41 to 5.77 HU which to a little extent exceeded the set ±5 HU tolerance range. Similarly, the presence of streak artifact was observed in the images obtained at one center.

Conclusion: Two out of the four computed tomography scanners assessed passed the four tests performed. Noise and artifact were the problem observed at centers B and C respectively. There was however no likelihood of periodic performance of these basic quality control tests at two of the centers in this study. Adequate records of quality control data should be kept regularly to allow in-depth analysis of failure rates of different tests, changes occurring during equipment lifetime and comparisons among CT scanners.