Assessment of water CT number, field uniformity and noise in diagnostics computed tomography scanners in Urmia metropolis, Iran

Since the dose received by patients should be minimized in computed tomography scan, the quality control of the
scanners is one of the main concerns. For this reason, quality control tests (water CT number, field uniformity and
noise) should be carried out regularly.The design used for this study was descriptive and cross-sectional. One private
radio-diagnostic center (A) and one government hospital (B) were selected for this study. Two CT scanners were
tested in the selected centers, one from center A, and one from center B. The phantoms used for the experiments were
head CT water phantom and we chose one ROI in the center of the image and four ROI’s at the periphery of the
image, then we recorded the mean values of the CT number and standard deviation that reported by the system for
these ROIs.Philips 64 slices scanner in center A has passed CT number for water, field uniformity and noise tests
because the values are within the acceptable limit and the Siemens 6 slices scanner has passed CT number for water,
field uniformity tests but don’t pass noise test because the measured values are out of the acceptable limit.CT scanners
in Urmia have passed the CT number for water and field uniformity tests, but the Siemens 6 slices scanner doesn’t
pass the standard deviation test