Development and Validation of a Complete GATE Model of the Siemens Inveon Trimodal Imaging Platform

This article presents and validates a newly developed GATE model of the Siemens Inveon trimodal imaging platform. Fully incorporating the positron emission tomography (PET), single-photon emission computed tomography (SPECT), and computed tomography (CT) data acquisition subsystems, this model enables feasibility studies of new imaging applications, the development of reconstruction and correction algorithms, and the creation of a baseline against which experimental results for real data can be compared. Model validation was based on comparing simulation results against both empirical and published data. The PET modality was validated using the NEMA NU-4 standard. Validations of SPECT and CT modalities were based on assessment of model accuracy compared to published and empirical data on the platform. Validation results show good agreement between simulation and empirical data of approximately ± 5%

GATE Validation of Standard Dual Energy Corrections in Small Animal SPECT-CT

<div><p>This paper addresses ¹²³I and ¹²⁵I dual isotope SPECT imaging, which can be challenging because of spectrum overlap in the low energy spectrums of these isotopes. We first quantify the contribution of low-energy photons from each isotope using GATE-based Monte Carlo simulations for the MOBY mouse phantom. We then describe and analyze a simple, but effective method that uses the ratio of detected low and high energy ¹²³I activity to separate the mixed low energy ¹²³I and ¹²⁵I activities. Performance is compared with correction methods used in conventional tissue biodistribution techniques. The results indicate that the spectrum overlap effects can be significantly reduced, if not entirely eliminated, when attenuation and scatter is either absent or corrected for using standard methods. In particular, we show that relative activity levels of the two isotopes can be accurately estimated for a wide range of organs and provide quantitative validation that standard methods for spectrum overlap correction provide reasonable estimates for reasonable corrections in small-animal SPECT/CT imaging.</p></div

Stacked bar plots of energy ratios and relative activity measurements.

<p>a). Low-to-high energy ratio e123 under different imaging conditions. b). Total ¹²³I activity in both high and low-energy windows.</p

Relative estimation error for three different imaging conditions: Ideal (no scatter medium), scatter and attenuation medium without corrections, and scatter and attenuation medium with corrections.

<p>Relative estimation error for three different imaging conditions: Ideal (no scatter medium), scatter and attenuation medium without corrections, and scatter and attenuation medium with corrections.</p

Illustrations of model components.

<p>a). GATE model of Siemens Inveon SPECT system configured with two MGP collimators. b). MWB collimator. c). MOBY attenuation phantom.</p

Estimated low-to-high energy (e123) ratios for selected organs in different sized mice.

<p>Estimated low-to-high energy (e123) ratios for selected organs in different sized mice.</p

Energy spectra of ¹²³I and ¹²⁵I for the MGP collimator.

<p>Energy spectra of ¹²³I and ¹²⁵I for the MGP collimator.</p

Comparison of real and simulated data.

<p>The top row shows real data for the uncorrected low energy window, high energy window, and the corrected low energy window. The bottom row shows the same information but for the simulated MOBY phantom data.</p

Development and Validation of a Complete GATE Model of the Siemens Inveon Trimodal Imaging Platform

This article presents and validates a newly developed GATE model of the Siemens Inveon trimodal imaging platform. Fully incorporating the positron emission tomography (PET), single-photon emission computed tomography (SPECT), and computed tomography (CT) data acquisition subsystems, this model enables feasibility studies of new imaging applications, the development of reconstruction and correction algorithms, and the creation of a baseline against which experimental results for real data can be compared. Model validation was based on comparing simulation results against both empirical and published data. The PET modality was validated using the NEMA NU-4 standard. Validations of SPECT and CT modalities were based on assessment of model accuracy compared to published and empirical data on the platform. Validation results show good agreement between simulation and empirical data of approximately ± 5%