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A Whole Body Dosimetry Protocol for Peptide-Receptor Radionuclide Therapy PRRT: 2D Planar Image and Hybrid 2D+3D SPECT/CT Image Methods
Published on: April 24, 2020
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Activity concentration measurements using a conjugate gradient (Siemens xSPECT) reconstruction algorithm in SPECT/CT.
Ian S Armstrong1, Sandra A Hoffmann
1aDepartment of Nuclear Medicine, Central Manchester University Hospitals, Manchester bDepartment of Nuclear Medicine, Salford Royal NHS Foundation, Salford, UK.
Nuclear Medicine Communications
|August 9, 2016
Summary
This study evaluates the accuracy of Siemens Healthcare's xSPECT algorithm for quantitative single photon emission computed tomography (SPECT). The xSPECT algorithm shows potential for accurate activity concentration measurements, with or without a cross-calibration factor (CCF).
Area of Science:
- Medical Imaging
- Nuclear Medicine
- Quantitative Imaging
Background:
- Quantitative single photon emission computed tomography (SPECT) is gaining interest for clinical applications.
- Vendors are developing software and hardware for 'SUV-SPECT' to align with positron emission tomography (PET) metrics.
- Accurate activity concentration measurements are crucial for quantitative SPECT analysis.
Purpose of the Study:
- To assess the accuracy of activity concentration measurements using Siemens Healthcare's new xSPECT algorithm.
- To evaluate the performance of xSPECT with manufacturer-defined presets.
- To determine the necessity and impact of a cross-calibration factor (CCF) on quantitative SPECT accuracy.
Main Methods:
- SPECT/CT data acquired from a uniform cylinder and a NEMA image quality phantom.
- Phantom spheres contained an 8:1 activity concentration ratio.
- Reconstructions performed using xSPECT algorithm with manufacturer presets.
- Dose calibrator-camera cross-calibration factor (CCF) derived from uniform phantom data.
Main Results:
- Positive bias observed in uniform phantom images (4-6%).
- CCF derived as 0.96 from higher-count uniform data.
- Negative bias in NEMA spheres, with positive bias in the four largest spheres.
- Gibbs edge enhancement suggested by non-monotonic recovery curves.
Conclusions:
- The xSPECT algorithm can achieve sufficiently accurate activity concentration measurements without a CCF.
- Using a CCF is likely to further improve quantitative accuracy.
- Manual conversion to Standardized Uptake Value (SUV) is feasible with accurate patient data.
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