Comparison of partial intrinsic performance of SPECT with two different crystal thickness

Objective: To explore the influence of changing probe crystal thickness on the performance of single photon emission computed tomography (SPECT), so as to achieve quantitative improvements and in-depth analyses of the related reasons and to provide effective measures in improving the image quality of SPECTs. Methods: Both 12 SPECT units each of 1 inch (1 inch = 2.54 cm) thick crystal and 35 SPECT units each of 3/8 inch thick crystal were chosen. Both intrinsic uniformity and intrinsic spatial resolution were measured according to the National Electrical Manufacturers Association (NEMA) standard. The performance was compared between SPECT units with 1 inch thick probe and 3/8 inch thick crystal. Results: The intrinsic uniformity measured for 1 inch thick probe and 3/8 inch thick crystal were (3.22 ± 0.83)% and (2.51 ± 0.65)%. The difference between the two groups was statistically significant (t = -3.601, P < 0.05). Intrinsic spatial resolutions of 1 inch thick probe and 3/8 inch thick crystal were (4.60 ± 0.14) and (3.70 ± 0.35) mm, with statistical significance between the two groups (t = -13.03, P < 0.05). Conclusions: The crystal thickness is a significant factor influencing SPECT's intrinsic uniformity and intrinsic spatial resolution. It is recommended that effective measures be taken to compensate the declined image quality due to crystal thickness change, to make sure the equipment is qualified for clinical use. (authors)