An integrated PET/CT simulation framework for virtual imaging trials and quantitative performance evaluation

The purpose of this study was to demonstrate the use of integrated PET/CT virtual imaging trials (VITs) for evaluating PET/CT acquisition protocols and clinically relevant sources of PET quantification variability under controlled, repeatable conditions.

An integrated PET/CT simulation framework was developed by combining SimSET for PET and DukeSim for CT, enabling concordant multi-modality simulations from a single human model input, including CT-derived attenuation correction. Geometric concordance was verified using an in-silico PET/CT coregistration test. Validation employed a NEMA IEC body phantom by comparing simulated PET/CT images with clinical scans using standard uptake value (SUV) and contrast recovery coefficient (CRC) metrics. Application studies assessed respiratory phase mismatch between PET and CT acquisitions, the impact of CT protocol selection on attenuation correction for free-breathing PET, and CT dose-reduction strategies for attenuation correction.

Geometric concordance was achieved with a maximum PET/CT centroid difference of 1.83 mm. Phantom validation demonstrated agreement between simulated and clinical PET quantification, with SUV measurements within 6% using CT-derived attenuation correction and within 12% using an ideal attenuation map. Application studies revealed that respiratory phase mismatch and CT protocol selection can produce clinically significant differences in PET quantification metrics. Dose-reduction studies showed minimal sensitivity of PET quantification to ultra-low-dose CT attenuation correction, with CRC deviations ≤ 0.23% across CT conditions for the same sphere size.

The integrated PET/CT simulation framework enables virtual imaging trials for controlled and reproducible investigations of PET/CT protocols, supporting multi-modality imaging optimization and quantitative performance evaluation under clinically relevant conditions.