A Comparison between Two Methods of Performing the Daily Intrinsic Uniformity Quality Control Test for Gamma Camera

Abstract

Field flood uniformity is a fundamental prerequisite for using the gamma camera in clinical routine. Different techniques are available for evaluating the intrinsic flood uniformity of dual head gamma camera during the daily quality control. Some manufacturers recommend a simultaneous acquisition (manufacturer method) using the two detectors and others use a single detector method (conventional method). A comparison of the two methods is questioned to determine how much difference might be seen if one of the two methods is applied routinely. Two methods were used to evaluate the intrinsic uniformity of a commercially available gamma camera (Siemens ECAM, Dual head) applying the following acquisition parameters: number of acquired counts, count rates, source volume, offset center x-axis, offset center y-axis and source-tocamera distance. One method uses the two detectors simultaneously (denoted by A) while the other method uses a one detector at a time (denoted by B). The integral and differential uniformity for the central and useful field of view were calculated and recorded for comparison. The acquisition parameters that achieved the optimal uniformity values are tabulated below. Method A demonstrated better uniformity values over that yielded by the conventional method B with respect to all acquisition parameters considered (p<0.05). Using the tabulated results, a daily routine of flood uniformity will take approximately a time of 7-10 min if method A is used while a time of 10-12 min is taken if the conventional single detector method is used.