The influence of acquisition parameters on the extrinsic uniformity on SPECT/CT gamma camera

Abstract

Author(s): Urška Šprajcer, Janez Žibert, Sebastijan Rep

Purpuse: The SPECT/CT gamma camera is the most commonly used imaging device in nuclear medicine. It is used to detect photons emanating from radioactive material. For its proper functioning, it is necessary to perform quality control tests regularly. One of the most important tests is extrinsic uniformity, which must be performed every day before starting work. We wanted to determine how extrinsic uniformity varies if we change the number of counts and the matrix size.

Methods: The measurements were carried out on SPECT/CT, where we placed a cobalt flood source between the two detectors. We used the protocol for uniformity where we used the different number of counts (3 million, 4.5 million, and 10 million) and different matrix sizes. Uniformity was calculated with the IAEA application in the program Image.

Results: The uniformity values are improved if we increase the number of counts (p<0.01). In most cases was determined that the matrix size does not affect uniformity (p>0.01). An exception was shown at integral uniformity with the useful field of view on detector one (p<0.01) and detector two (p<0.01).

Conclusion: By increasing the number of counts, the uniformity of the detector system improves. The matrix size does not have a significant effect on the uniformity of the detector system.

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