The aim of this work is to measure the collimator’s quality with system uniformity parameter. According to the NEMA standards publication (No. NU 1-1994)

four low energy general purpose parallel hole collimators and four low energy high resolution parallel hole collimators had been measured for the system flood field uniformity

the system spatial resolution and system planar sensitivity

and then all of the results were analysed. Results showed that the system spatial resolution and system planar sensitivity parameters of the same type collimators were almost close to each other

but the uniformity parameters were greatly different (when the collimators have quality defect)

three of the eight collimators with which the system integral uniformity and differential uniformity exceed by 6% and 3% were proved to be detective in quality. This indicated that the performance of collimator can be reflected quantitatively and qualitatively by the uniformity measurement

and the quality of collimator can be found through it effectively.