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Performance characterization of a portable pixelated CdTe miniature gamma camera

¹ Imaging Physics, UT MD Anderson Cancer Center, Houston, Texas

1687

Objectives: To develop and perform characterization tests on a small, solid state gamma camera [MGC500, PreXion, San Mateo CA] that uses a 32 by 32 pixelated cadmium telluride detector array with a 44.8x44.8 mm useful field-of-view (FOV).

Methods: Tests were adapted from standards documents and the literature to evaluate energy resolution, rotational uniformity, extrinsic spatial resolution, sensitivity, intrinsic count rate performance, intrinsic uniformity, and relative spatial count rate dependency using Tc99m or Co57 as appropriate. Also, measurements of the diverging collimator FOV size were performed.

Results: Energy resolution was estimated to be 5.5%. Integral uniformity changed by more than 5% over the range of detector orientations tested. Extrinsic spatial resolution in scatter-free conditions was observed to be 3.2 mm for parallel hole and 2.8 mm for the diverging collimator. Camera sensitivity was measured with Tc-99m (20% energy window) to be 707 cpm/uCi with the standard collimator and 109 cpm/uCi using the high resolution collimator. The maximum intrinsic count rate observed at 5 FOV from the detector was 15.2 Mcpm using 101 mCi of Tc-99m and 8.4 mm of Cu attenuator. Positioning two sources of similar activity at various spatial locations in the field of view produced little effect on the observed count rate. The daily intrinsic integral uniformity had a mean value of 12.9% and standard deviation of 1.3%. The complete FOV for the diverging collimator using a source-to-collimator distance of 30 cm was 19x19 cm. Significant gamma ray leakage through the sides and back of the detector assembly was observed.

Conclusions: This small field of view gamma camera demonstrates good spatial resolution, energy resolution and count rate performance, but would benefit from better shielding and higher sensitivity.

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Lofton, B. Articles by Wendt, R. PubMed Articles by Lofton, B. Articles by Wendt, R.