Tomographic image quality of rotating slat versus parallel hole-collimated SPECT

Abstract

Abstract. Parallel and converging hole collimators are most frequently used in nuclear medicine. Less common is the use of rotating slat collimators for Single Photon Emission Computed Tomography (SPECT). The higher photon collection efficiency, inherent to the geometry of rotating slat collimators results in much lower noise in the data. However, plane integrals contain spatial information in only one direction, whereas line integrals provide two-dimensional information. It is not a trivial question whether the initial gain in efficiency will compensate for the lower information content in the plane integrals. Therefore, a comparison of the performance of parallel hole and rotating slat collimation is needed. This study compares SPECT with rotating slat and parallel hole collimation in combination with MLEM reconstruction with accurate system modeling and correction for scatter and attenuation. A contrast-to-noise study revealed an improvement of a factor 2 to 3 for hot lesions and more than a factor of 4 for cold lesion. Furthermore, a clinically relevant case of heart lesion detection is simulated for rotating slat and parallel hole collimators. In this case, rotating slat collimators outperform the traditional parallel hole collimators. We conclude that rotating slat collimators are a valuable alternative for parallel hole collimators.

Parallel Hole and Rotating Slat Collimators: Comparative Study Using Digital Contrast Phantoms

“…However, in volume imaging, the gain of using the RS collimator in our study is very different from that proposed in [12], where it was found that the RS collimator is 2-3 times better than the PH in hot spot imaging, and more than 4 times better in cold spot imaging. One of the main reasons is that the collimator apertures in [11], [12] were the same for both collimators, whereas in our study we applied the optimal collimator aperture for each system to ensure a fair comparison. The discrepancy could also be partially explained by the influence of photon scatter, which was modelled in [12] but not in this paper.…”

“…One of the main reasons is that the collimator apertures in [11], [12] were the same for both collimators, whereas in our study we applied the optimal collimator aperture for each system to ensure a fair comparison. The discrepancy could also be partially explained by the influence of photon scatter, which was modelled in [12] but not in this paper. The dimensions of the phantom used in this study were relatively small compared to the human size.…”

“…They applied the same type of detector with the same dimension, and used Monte Carlo simulations for accurate system modeling. The two collimator systems were compared in planar imaging [11] and volume imaging [12], respectively, using the maximum likelihood expectation maximization (MLEM) reconstruction. The conclusion was that for planar imaging, the PH collimator only outperforms RS for cold lesions in a very large warm background, whereas in tomographic imaging, the RS always outperforms the PH system.…”