الفهرس 
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Abstract
Since its inception in 1973, Magnetic Resonance Imaging (MRI) has largely been utilized for qualitative diagnosis of diseases. Physicians or radiologists inspected nuclear magnetic resonance (NMR) images looking for signs of abnormality. However, more recently, health practitioners are concerned with the quantitative aspects that MRI can contribute to the diagnosis. As when any system is quantified, repeatability and comparison of measurements are motivating factors.For this reason, institutions like the American College of Radiology (ACR) developed accreditation programs for MRI scanners as well as for devices corresponding to other imaging modalities. The ACR MRI accreditation program requires facilities to submit clinical and phantom images for an assessment of scan quality. The ACR also recommends that sites carry out daily quality assurance (QA) testing and they provide a QA procedure that is similar to their accreditation program. However, if the actual accreditation program is used as a daily QA procedure, sites would have very high probability of attaining accreditation on the first trial. The QA procedure could serve to pre-qualify images before submission to the ACR for accreditation.Of primary interest in the ACR accreditation program is the phantom image assessment portion. The ACR provides a physical phantom to participating facilities that provides ground truth measurements for various tests. This phantom is imaged according to a pre-defined protocol and the images are to be sent in for the ACR to perform the various associated tests. With the ACR accreditation program being utilized for daily QA, the images can also be analyzed on site.There are two issues of concern with this procedure. First, the accreditation program procedure involves individuals performing manual tests. That is, someone views the images and performs the associated tests using various on-screen measurement tools. As one can imagine, this is a very tedious task, which deters site employees from carrying out the QA testing on a daily basis.Secondly, it has been shown that human testing by visual inspection is not objective since factors such as fatigue and visual perception variation come into play.The ACR accreditation program uses information obtained from clinical and phantom images to assess overall image quality of a scanner.The 1.5 Tesla MRI scanner (Signa Horizon LX Echo Echospeed, General Electric Healthcare, Milwaukee, WI, USA) and a standard head coil were used besides the ACR phantom in this work. Seven necessary estimations of MRI image quality (Geometric accuracy, High-contrast spatial resolution, Slice thickness accuracy, Slice position accuracy, Image intensity uniformity, Percent-signal ghosting, Low-contrast object detectability) were tested using the ACR phantom. Our results show seven necessary estimations of NMR image quality were tested and showed that for the Geometric accuracy test seven measurements were made which was accepted with the tolerance value. For the High-contrast spatial resolution test we can in visual evaluation differentiate holes with the diameter of 1.0 mm at least. For the Slice thickness accuracy test the two special signal ramps lengths were measured. For the Slice position accuracy test the length difference of special bars in two slices was measured which was considered within tolerance value. For the Image intensity uniformity, the PIU was 96.2% which is more than or equal to 87.5% with field strengths less than 3 T for the MRI systems. For the Percent-signal ghosting the ghosting ratio was calculated 0.0002 which was less than or equal to 0/025. For the Low-contrast object detectability test the sum of spoke was 30, this means the low-contrast objects images were discernible. Finally, All the ACR MRI quality assurance tests were performed successfully. We recommend that image quality test for MRI must be performed in other Egyptian and African centers, because image quality tests are very important tests in acceptance of any MRI scanner after installation and during maintenance to approve that the image parameters are accepted by using ACR phantom.