الفهرس 
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Abstract
Gamma camera is the mainly device in the nuclear medicine, so it is necessary to ensure that this device works at high efficiency, from this point of veiw the quality control is utilized to exploit the optimum parameters which lead to high efficiency images.
The present study investigates some parameters affecting planar and SPECT such as :
1- count rate with resolution .
2- relation between activity and count rate .
3- effect of distance on resolution.
-In SPECT we study the following parameters :
1-effect of type of collimator on the resolution .
2-effect of the number of veiw on resolution .
3-effect of the time per veiw on resolution .
4- effect of the window width on resolution .
5- effect of the matrix size on resolution.
6- effect of the count rate on resolution .
And the experimental results demonstrats that;
1- with respect to the relation between resolution and count rate the optimum range for this version of gamma camera is between 26.3 Kcps and 44.3 Kcps.
2- with respect to the relation activity and count rate it was found that count rate is increased as the activity increased until it reachs to maximum value and then it decreases, and this is due to the dead time and it was calculated by using the two source method and it equal to 3.4 s.
3- with respect to the relation between distance and resolution it was found that resolution gets worse as the distance is increased and this is due to the divergence of the beam.
4- with respect to the relation type of collimator and resolution it was found that , ultra high-resolution collimator, rather than high-resolution collimator, is recommended in order to provide good spatial resolution. Although the changing to higher resolution collimator leads to a decrease in the number of counts, this decrease could be compromised by other parameter such as increasing the number of veiw or time per veiw.
On the other hand patiant motion during data aquasition in SPECT could couse serious reconstruction artifacts. A cine display is recommended to identify movement artifacts.
5- the icrease in the number of veiw leads to good defination of the SPECT images. In our sudy 60 NOV gave the best image quality, rather than 20 or 30 veiw . In clinical applications, approximatly 60 veiw is adequate for the most clinical studies.
6- The longer the acquisition time per veiw TPV, the more event are obtained, but at the expense of possible artifacts from patiant movement. So, we could go down to 30 or 20 s TPV without much loss of image quality. We have to consider the whole time of acquisition to be suitable to patiant stability, whenever we plan the acquisition parameters.
7- In the case of energy window width, it was noticed that , the resolution improved and the total count decreased when decreasing the energy window width. This improvement in resolution due to scatter reduction in the case of 15% energy window compred with the standard 20% symmetric energy window around 140 KeV photopeak of Tc 99m.
8- In the case of matrix size, the results obtained show that there is a great difference between images obtained with a 64x64 image matrix and that using a 128x128 matrix. That difference concentrated around the image resolution.Matrix size 128x128 give the best resolution than matrix 64x64. smallar pixel size 128x128 could display more image details than 64x64.
9- In the case of count rate with contrast it was foun that the optimum range of count rate for good contrast is btween 43 Kcps and 62 Kcps.