Continual technical development of CT scanners has increased its complexity and clinical application. Therefore, proper monitoring is required to optimize procedures for diagnostic quality and patient dose. Thus, to ensure that the system is fulfilling its technical specifications, a routine quality assurance program is necessary to detect drifting or degradation of system performance overtime. The main goal of this study was to evaluate the stability and reproducibility of essential image quality parameters of seven scanners from four vendors over time.

Phantoms Catphan 500 and 600 (The Phantom Laboratory, Salem, NY, USA) designed for assessing various CT image quality parameters were used in this study [1]. The phantoms consist of 4/5 test modules enclosed in 20 cm housing. In this study, sensitometry(CTP401/CTP404), image uniformity (CTP486), low contrast (CTP515) and high resolution (CTP528) moduleswere used. The sensitometry module in Catphan 500 (CTP401) consist of air, teflon, acrylic, and low-density polyethylene (LDPE) inserts [1]. In addition to the above-mentioned inserts, the CTP404 module in Catphan 600 has delrin,...

CT number Time averaged CT numbers for each sensitometric inserts are displaced in Table 2 . HU of different materials showed a linear relationship (R2 = 0.9985) with their respective attenuation coefficients over time (Fig. 2A). Data from the same scanner revealed minor drifts (≤ 8%) from baseline values for all inserts with the exception of polystyrene, where the deviations (13% for scanner A and -12% for scanner E) were outside the recommended limits [5] (Fig. 2B). Comparedto theoretical values, there was a drift in...

All image quality parameters measuredfor the seven scanners over a four year period of time were stable independent of vendor and scanner model. However, a drift in HU was seen in some of the sensitometric inserts for the same scanner over time and also between the different scanners. This implies that the use of HU for quantification and characterization of tissues should be used with care.

H. K. Andersen; Oslo/NO - Other at Oslo university hospital has an institutional research agreement with GE Healthcare M. Afadzi; Oslo/NO - Other at Oslo university hospital has an institutional research agreement with GE Healthcare B. H. Østerås; Oslo/NO - Other at Oslo university hospital has an institutional research agreement with GE Healthcare K. Jensen; Oslo/NO - Other at Oslo university hospital has an institutional research agreement with GE Healthcare I. H. R. Hauge; Oslo/NO - Other at Oslo university hospital has an institutional research...

The Phantom Laboratory 2006 Catphan®500 and 600 Manual (salem, NY, USA). Available via www.phantomlab.com. Accessed13th January 2020. International standard IEC 61223-2-6. Evaluation and Routine Testing in Medical Imaging Departments - Part 3-5 : AcceptanceTests - ImagingPerformance of Computered Tomography X-ray Equipment.IEC 61223-3-5.1st ed. Geneva: IEC; 2004 International standard IEC 61223-2-6. Evaluation and Routine Testing in Medical Imaging Departments-Part2-6: Constancy Tests-Imaging Performance of Computered Tomography X-ray Equipment. IEC 61223-2-6.2nd ed. Geneva: IEC; 2006 American Association of Physicists in Medicine (AAPM). Quality Control in Diagnostic Radiology. AAPM...