Abstract

Aim

To evaluate the effect of combining positron range correction (PRC) with point-spread-function (PSF) correction and to compare different methods of implementation into iterative image reconstruction for 124I-PET imaging.

Materials and methods

Uniform PR blurring kernels of 124I were generated using the GATE (GEANT4) framework in various material environments (lung, water, and bone) and matched to a 3D matrix. The kernels size was set to 11 × 11 × 11 based on the maximum PR in water and the voxel size of the PET system. PET image reconstruction was performed using the standard OSEM algorithm, OSEM with PRC implemented before the forward projection (OSEM+PRC simplified) and OSEM with PRC implemented in both forward- and back-projection steps (full implementation) (OSEM+PRC). Reconstructions were repeated with resolution recovery, point-spread function (PSF) included. The methods and kernel variation were validated using different phantoms filled with 124I acquired on a Siemens mCT PET/CT system. The data was evaluated for contrast recovery and image noise.

Results

Contrast recovery improved by 2–10% and 4–37% with OSEM+PRC simplified and OSEM+PRC, respectively, depending on the sphere size of the NEMA IQ phantom. Including PSF in the reconstructions further improved contrast by 4–19% and 3–16% with the PSF+PRC simplified and PSF+PRC, respectively. The benefit of PRC was more pronounced within low-density material. OSEM-PRC and OSEM-PSF as well as OSEM-PSF+PRC in its full- and simplified implementation showed comparable noise and convergence. OSEM-PRC simplified showed comparably faster convergence but at the cost of increased image noise.

Conclusions

The combination of the PSF and PRC leads to increased contrast recovery with reduced image noise compared to stand-alone PSF or PRC reconstruction. For OSEM-PRC reconstructions, a full implementation in the reconstruction is necessary to handle image noise. For the combination of PRC with PSF, a simplified PRC implementation can be used to reduce reconstruction times.

Details

Title
Positron range in combination with point-spread-function correction: an evaluation of different implementations for [124I]-PET imaging
Author
Kertész, Hunor 1   VIAFID ORCID Logo  ; Conti, Maurizio 2 ; Panin, Vladimir 2 ; Cabello, Jorge 2 ; Bharkhada, Deepak 2 ; Beyer, Thomas 1 ; Papp, Laszlo 1 ; Jentzen, Walter 3 ; Cal-Gonzalez, Jacobo 4 ; Herraiz, Joaquín L. 5 ; López-Montes, Alejandro 6 ; Rausch, Ivo 1 

1  Medical University of Vienna, QIMP Team, Center for Medical Physics and Biomedical Engineering, Vienna, Austria (GRID:grid.22937.3d) (ISNI:0000 0000 9259 8492) 
2  Siemens Medical Solutions USA, Inc., Knoxville, USA (GRID:grid.22937.3d) 
3  University Hospital Essen, Clinic for Nuclear Medicine, Essen, Germany (GRID:grid.410718.b) (ISNI:0000 0001 0262 7331) 
4  Medical University of Vienna, QIMP Team, Center for Medical Physics and Biomedical Engineering, Vienna, Austria (GRID:grid.22937.3d) (ISNI:0000 0000 9259 8492); Protontherapy Center Quironsalud, Ion Beam Applications, Madrid, Spain (GRID:grid.22937.3d) 
5  University Complutense of Madrid, Nuclear Physics Group and IPARCOS, Faculty of Physical Sciences, Madrid, Spain (GRID:grid.4795.f) (ISNI:0000 0001 2157 7667); Health Research Institute of the Hospital Clínico San Carlos, Madrid, Spain (GRID:grid.414780.e) 
6  University Complutense of Madrid, Nuclear Physics Group and IPARCOS, Faculty of Physical Sciences, Madrid, Spain (GRID:grid.4795.f) (ISNI:0000 0001 2157 7667) 
Publication year
2022
Publication date
Dec 2022
Publisher
Springer Nature B.V.
e-ISSN
21977364
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1186/s40658-022-00482-y
ProQuest document ID
2704123096
Copyright
© The Author(s) 2022. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.