Implementation of an analytically based scatter correction in SPECT reconstructions

Abstract

Photon scattering is one of the main effects contributing to the degradation of image quality and to quantitative inaccuracy in nuclear imaging. We have developed a scatter correction based on a simplified version of the analytic photon distribution (APD) method, and have implemented it in an iterative image reconstruction algorithm. The scatter distributions generated using this approach were compared to those obtained using the original APD method. Reconstructions were performed using computer simulations, phantom experiments, and patient data. Images corrected for scatter, attenuation, and collimator blurring were compared to images corrected only for attenuation and collimator blurring. In the simulation studies, results were compared to an ideal situation in which only the primary (unscattered) photon data were reconstructed. Results showed that in all cases, the scatter-corrected images demonstrated substantially improved image contrast relative to no scatter correction. For simulated data, scatter-corrected images had very similar contrast and noise properties to the primary-only reconstructions. Additional work is required to further reduce the computation times to clinically viable amounts.Index Terms-Compton scatter, image reconstruction, Klein-Nishina formula, scatter correction, single photon emission computed tomography (SPECT).

Patient-Specific Radiation Dosimetry of 99mTc-HYNIC-Tyr3-Octreotide in Neuroendocrine Tumors

“…In all cases, the reconstruction used 6 iterations and 10 subsets and included resolution recovery and CT-based attenuation and analytic scatter corrections (15,16). A calibration experiment was performed to determine the sensitivity of the camera (in cpm/ kBq) so that counts in the reconstructed images could be translated into absolute activity.…”

A multi-center phantom study comparing image resolution from three state-of-the-art SPECT-CT systems

“…Our SC uses an analytical APD method (based on the Klein-Nishina formula), which calculates the distributions of scattered photons and incorporates them into the forward projection step of OSEM. 12 As the MIRG software is very flexible, allowing us to use any combination of these corrections for a given reconstruction, we tested the resulting MWT measurements for a series of different reconstructions: OSEM ? AC, OSEM ?…”

“…However, two of the SC techniques that are implemented in clinical systems are based on rather simple approaches, such as the dual energy window (DEW) technique which is utilized by Siemens and GE, 8 while the effective scatter source estimation (ESSE) 9 has been employed by Philips. More sophisticated approaches, which include Monte Carlo based methods 10 and analytical photon distribution (APD) techniques, 11,12 offer improved quantitative accuracy but continue to require extensive calculation times, making them currently impractical for clinical use.…”

An investigation of potential sources of artifacts in SPECT-CT myocardial perfusion studies

“…As the details of the GE reconstruction algorithms are largely unknown, in parallel, all datasets were reconstructed using the OSEM-based proprietary Medical Imaging Research Group (MIRG) reconstruction qSPECT software. [13][14][15][16] This approach allowed us to maintain full control and understanding of the parameters used in the reconstructions. In this case, three different software configurations were used: (a) NC, (b) with CT-based AC, and (c) with AC and 3D resolution recovery (RR).…”