Experimental evaluation of the GE NM/CT 870 CZT clinical SPECT system equipped with WEHR and MEHRS collimator

Abstract

Purpose A high‐energy‐resolution whole‐body SPECT‐CT device (NM/CT 870 CZT; C‐SPECT) equipped with a CZT detector has been developed and is being used clinically. A MEHRS collimator has also been developed recently, with an expected improvement in imaging accuracy using medium‐energy radionuclides. The objective of this study was to compare and analyze the accuracies of the following devices: a WEHR collimator and the MEHRS collimator installed on a C‐SPECT, and a NaI scintillation detector‐equipped Anger‐type SPECT (A‐SPECT) scanner, with a LEHR and LMEGP. Methods A line phantom was used to measure the energy resolutions including collimator characteristics in the planar acquisition of each device using 99mTc and 123I. We also measured the system's sensitivity and high‐contrast resolution using a lead bar phantom. We evaluated SPECT spatial resolution, high‐contrast resolution, radioactivity concentration linearity, and homogeneity, using a basic performance evaluation phantom. In addition, the effect of scatter correction was evaluated by varying the sub window (SW) employed for scattering correction. Results The energy resolution with 99mTc was 5.6% in C‐SPECT with WEHR and 9.9% in A‐SPECT with LEHR. Using 123I, the results were 9.1% in C‐SPECT with WEHR, 5.5% in C‐SPECT with MEHRS, and 10.4% in A‐SPECT with LMEGP. The planar spatial resolution was similar under all conditions, but C‐SPECT performed better in SPECT acquisition. High‐contrast resolution was improved in C‐SPECT under planar condition and SPECT. The sensitivity and homogeneity were improved by setting the SW for scattering correction to 3% of the main peak in C‐SPECT. Conclusion C‐SPECT demonstrates excellent energy resolution and improved high‐contrast resolution for each radionuclide. In addition, when using 123I, careful attention should be paid to SW for scatter correction. By setting the appropriate SW, C‐SPECT with MEHRS has an excellent scattered ray removal effect, and highly homogenous imaging is possible while maintaining the high‐contrast resolution.

Satisfied quantitative value can be acquired by short-time bone SPECT/CT using a whole-body cadmium–zinc–telluride gamma camera

“…Tracers with more complex kinetics, such as 99m Tc-sestamibi or even new radiopharmaceuticals, could be evaluated. In addition to 99m Tc labeled tracer, the development of new collimators of wide-energy high-resolution or medium-energy high-resolution can acquire images of other radionuclides, including 123 I or 177 Lu, that can apply for the dosimetry of radionuclide therapy 27 .…”

New Radionuclides and Technological Advances in SPECT and PET Scanners

“… GE Discovery: CZT SPECT device. Figure from [ 11 ]. Representation of the detector arrangement for a general-purpose CZT device.…”

“…This was subsequently overcome with the development of cadmium-zinc-telluride (CZT) crystals [10]. Due to the large size of the band gap in the CZT detector, it can be used at room temperature, and the high atomic number of CZT assists in efficient photoelectric absorption, leading to an improved system sensitivity compared with that of the sodium iodine (NaI) detector [11]. The first clinical CZT devices that were introduced were anatomically specific for cardiac examinations [12][13][14][15][16][17][18][19].…”

Monte Carlo modelling of a compact CZT-based gamma camera with application to 177Lu imaging

“…[ 1 , 3 , 6 ]). The two major vendors for clinical CZT cameras are GE Healthcare and Spectrum Dynamics Medical, that offer SPECT systems like the Discovery NM530c [ 1 ], D-SPECT [ 2 ], Discovery 870 CZT [ 5 ], Veriton [ 6 ] and StarGuide [ 7 ]. CZT-based cameras do, however, typically present undesirable spectrum features known as low-energy tails, which result from poor charge carrier transport properties (low mobilities or short lifetimes), particularly for holes, an issue prevalent among compound semiconductors [ 8 ].…”

“…This is a system centred around a single CZT-module [ 25 ], whose specifications are identical or similar to modules found in full-size gamma cameras (e.g. [ 1 , 2 , 4 , 5 ]), and the developed model should therefore be relevant for such systems as well (personal communication, Aharon Peretz, General Electric, retired).…”