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Iranian Journal of Medical Physics، جلد ۲، شماره ۳، صفحات ۱-۸
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عنوان انگلیسی Assessment of Reproducibility of Geometric Distortion in MRI using Phantom Measurements
چکیده انگلیسی مقاله Introduction: Image distortion is one of the major problems of magnetic resonance imaging (MRI) for use in 3DMRI, velocity MRI, FMRI and radiotherapy treatment planning (RTTP). It is widely known that the most obvious effect of the inhomogenity of the magnetic fields and the nonlinearity of the gradient is the Geometric Distortion of MR tomograms. In this study, the accuracy of MR images was considered by the phantom study and the reproducibility of images was evaluated by repeating the phantom measurements. Materials and Methods: MRI scans of the phantom with grid pattern inside it were performed using head coil in two 1.5 Tesla MRI systems (Picker VISTA TM HPQ, USA & GE Signa Echo Speed, USA). For the Geometric Distortion reproducibility evaluation the T1W, T2W and PDW SE protocols were repeated three times. The Geometric Distortion was measured by an edge detection program in MATLAB. Results: The geometric distortion in the peripheral area of the images tends to be generally larger than it in the central area in all images. The average displacement in Picker MRI was 3 pixels in the y and 1 pixel in the x direction and in GE MRI it was 1 pixel in both x and y direction for 24 cm FOV (pixel = 0.9 mm). Discussion and Conclusions: Since the positional variation was within 1 to 3 pixels for the head coil, it will be possible to use this MR system in 3DMRI, velocity MRI, FMRI and RTTP. To decrease the geometric distortion the use of suitable coil and protocol are expected.
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نویسندگان مقاله m ashkanmehr | m. ashkanmehr
m.sc. in nuclear engineering dept., islamic azad university, tehran, iran.

سازمان اصلی تایید شده: دانشگاه آزاد اسلامی علوم و تحقیقات (Islamic azad university science and research branch)

n ریاحی عالم | n riyahi alam
associate professor, physics and biomedical engineering, tehran university of medical sciences, tehran, iran. research center for science amp;amp; technology in medicine, imam khomeini hospital, tehran. iran.

سازمان اصلی تایید شده: دانشگاه علوم پزشکی تهران (Tehran university of medical sciences)

محمدعلی عقابیان | m a oghabian
associate professor, physics and biomedical engineering, tehran university of medical sciences, tehran, iran. research center for science amp;amp; technology in medicine, imam khomeini hospital, tehran. iran.

سازمان اصلی تایید شده: دانشگاه علوم پزشکی تهران (Tehran university of medical sciences)

a قاسم زاده | a. ghasemzadeh
m. sc. in research center for science amp;amp; technology in medicine, imam khomeini hospital, tehran. iran.


m بختیاری | m. bakhtiary
m. sc. in research center for science amp;amp; technology in medicine, imam khomeini hospital, tehran. iran.


h قناعتی | h. ghanaati
associate professor, radiology dept., medical imaging center, imam khomeini hospital, tehran university of medical sciences , tehran, iran.

سازمان اصلی تایید شده: دانشگاه علوم پزشکی تهران (Tehran university of medical sciences)

h هاشمی | h. hashemi
assistant professor, radiology dept., medical imaging center, imam khomeini hospital, tehran university of medical sciences , tehran, iran.

سازمان اصلی تایید شده: دانشگاه علوم پزشکی تهران (Tehran university of medical sciences)

m پاکروان | m. pakravan
b. sc. in medical imaging center, imam khomeini hospital, tehran university of medical sciences, tehran, iran.

سازمان اصلی تایید شده: دانشگاه علوم پزشکی تهران (Tehran university of medical sciences)

n شاکری | n. shakeri
m. sc. in research center for science amp;amp; technology in medicine, imam khomeini hospital, tehran. iran.
نشانی اینترنتی http://ijmp.mums.ac.ir/article_8116.html
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