Results of Daily Quality Control in Computed Tomography

Regular quality control in computed tomography (CT) in Bosnia and Herzegovina is made mandatory by national regulations. Conducting daily quality control (QC) tests is the responsibility of radiographers, also known as radiological technologists. Basic tests prescribed by the Ordinance are: Image noise, and CT number uniformity and accuracy. The purpose of this paper is to perform analysis of daily image QC tests and to compare the results of different imaging methods and reconstruction on CT devices, as well as to evaluate more complex image quality parameters, such as noise power spectrum (NPS). This research was conducted as a retrospective-prospective study done within 4-month period at the Clinical center of the University of Sarajevo. A 100 scans with 3 different CT devices were included in the study. Image noise analysis with standard deviation and NPS, as well as CT number uniformity and accuracy was performed using different scanning parameters and reconstructions utilizing the standard water phantom. All results conformed the criteria from regulations. Overall, the results of this study showed stability over time for all image quality tests that indicates the regularity of CT imaging systems. Image quality tests are very important in accepting operation of any CT device after installation and during maintenance to confirm that the image parameters are acceptable by using the phantom. This research can serve as a guideline for advanced daily image quality control tests for computerized tomography devices, using modern image quality metrics.