Validation of a Monte Carlo simulated cardiac phantom for planar and SPECT studies

This work aimed to validate Monte Carlo (MC) simulated cardiac phantoms for the evaluation of planar- and SPECT-gated-blood-pool (GBP-P and GBP-S) studies.

A comparison of gamma camera system performance criteria measurements (energy resolution, spatial resolution, sensitivity) with MC simulations was conducted. Furthermore, the accuracy of measured and simulated volumes of two stereolithography-printed cardiac phantoms (based on 4D-XCAT phantoms) was assessed. Finally, the simulated GBP-P and GBP-S XCAT studies were validated by comparing calculated left ventricular ejection fraction (LVEF) and ventricle volume values with known parameters.

The simulated performance criteria compared well with measured values (energy resolution difference: 0.1 ± 0.10%; spatial resolution (full width at half maximum) difference ≤ 0.5 ± 0.8 mm and system sensitivity difference ≤ 6.2 ± 0.62cps/MBq). The measured and simulated cardiac phantoms were in good agreement; the left anterior oblique views compared well. This is supported by line profiles through these phantoms and on average, simulated counts were 5.8% lower than measured counts. The LVEF values calculated from the GBP-P and GBP-S simulated data differ from known values (2.8 ± 0.64% and 0.8 ± 0.52%). The differences between the known XCAT LV volumes and simulated GBP-S calculated volumes were -1.2 ± 1.91 ml and -1.5 ± 0.96 ml for the end-diastolic and end-systolic volumes.

The MC-simulated cardiac phantom has been validated successfully. Stereolithography-printing allows researchers to create clinically realistic organ phantoms and is a valuable tool for validating MC simulations and clinical software. By conducting GBP simulation studies with various XCAT models, the user will be able to generate GBP-P and GBP-S databases for future software evaluation.