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Instrumentation & Data Analysis: Image GenerationImage Generation Posters |
1 Molecular and Medical Pharmacology, UCLA, Los Angeles, California
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1642
Objectives: Several studies have investigated attenuation correction methods for respiratory gated positron emission tomography (PET) and its role in misalignment of tumor volumes between the emission data and attenuation map. The aim of this study was to investigate the impact of scatter and attenuation corrections on lesion quantification in respiratory gated PET.
Methods: The NCAT phantom was simulated to have a spherical lung lesion located in either the middle or base of the right lung. The lesion had a contrast ratio of 5:1 or 10:1 and either a 1 cm or 2 cm diameter. Data were binned into 16 gates and were forward projected to produce sinograms. Scatter distributions for each gate were generated using the Watson single scatter technique. Peak exhale sinograms were reconstructed using attenuation and scatter maps from different respiratory phases. Regions of interest were placed around the centroid of each lesion and the maximum lesion signal was measured.
Results: Reconstructing the peak exhale emission data with either the average or peak inhale scatter distribution did not affect lesion quantification with respect to lesion size, contrast or location. However, reconstructing the peak exhale emission data with the average and peak inhale attenuation map underestimated the maximum signal by 30-68% and overestimated the maximum signal by 6-42%, respectively. In the case of the 10:1 lesion contrast, the maximum signal was severely underestimated by 84% and 46% when using the average and peak inhale attenuation maps, respectively.
Conclusions: These results show that the scatter distribution across all respiratory phases is consistent and does not significantly affect image quality or quantification of respiratory gated data. Additionally, using a mismatched or temporally averaged attenuation map can significantly distort image quality and lesion quantification.
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