Monte Carlo Modeling of Gamma Cameras for I-131 Imaging in Targeted Radiotherapy

Autret, D.; Bitar, A; Ferrer, Ludovic; Lisbona, A.; Bardiès, Manuel

doi:10.1089/cbr.2005.20.77

Cited by 51 publications

(31 citation statements)

References 13 publications

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“…Camera geometry and features: The GATE simulator allows any gamma camera simulation, provided that an accurate description of the system is given. 6,7 Model-specific gamma camera information is stored in the 'Camera' database (see figure 1). …”

Section: Simulation Of Spect Imagesmentioning

confidence: 99%

TestDose: a SPECT image generator for clinical dosimetry studies

Sarkissian¹,

McKay²,

Ferrer³

et al. 2013

Medical Imaging 2013: Physics of Medical Imaging

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Patient-specific dosimetry in nuclear medicine relies on activity quantification in volumes of interest from scintigraphic imaging. Clinical dosimetry protocols have to be benchmarked against results computed from test phantoms. The design of an adequate model is a crucial step for the validation of image-based activity quantification. We propose a computing platform to automatically generate simulated SPECT images from a dynamic phantom for arbitrary scintigraphic image protocols. As regards the image generation, we first use the open-source NCAT phantom code to generate an anatomical model and 3D activity maps for different source compartments. This information is used as input for an image simulator and each source is modelled separately. Then, a compartmental model is designed, which describes interactions between different functional compartments. As a result, we can derive time-activity curves for each compartment with sampling time determined from real image acquisition protocols. Finally, to get an image at a given time after radionuclide injection, the resulting projections are aggregated by scaling the compartment contribution using the specific pharmacokinetics and corrupted by Poisson noise. Our platform consists of many software packages, either in-house developments or open-source codes. In particular, an important part of our work has been to integrate the GATE simulator in our platform, in order to generate automatically the command files needed to run a simulation. Furthermore, some developments were added in the GATE code, to optimize the generation of projections with multiple energy windows in a minimum computation time.

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Section: Simulation Of Spect Imagesmentioning

confidence: 99%

TestDose: a SPECT image generator for clinical dosimetry studies

Sarkissian¹,

McKay²,

Ferrer³

et al. 2013

Medical Imaging 2013: Physics of Medical Imaging

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“…Autret et al (2005) showed the impact of the scattered and septal penetration photons in the projection images by means of Monte Carlo simulations.…”

Section: System Matrix Pmentioning

confidence: 99%

System matrix computation for iterative reconstruction algorithms in SPECT based on direct measurements

Borys

Szczucka-Borys

Gorczewski

2011

International Journal of Applied Mathematics and Computer Science

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A method for system matrix calculation in the case of iterative reconstruction algorithms in SPECT was implemented and tested. Due to a complex mathematical description of the geometry of the detector set-up, we developed a method for system matrix computation that is based on direct measurements of the detector response. In this approach, the influence of the acquisition equipment on the image formation is measured directly. The objective was to obtain the best quality of reconstructed images with respect to specified measures. This is indispensable in order to be able to perform reliable quantitative analysis of SPECT images. It is also especially important in non-hybrid gamma cameras, where not all physical processes that disturb image acquisition can be easily corrected. Two experiments with an 131 I point source placed at different distances from the detector plane were performed allowing the detector response to be acquired as a function of the point source distance. An analytical Gaussian function was fitted to the acquired data in both the one-and the two-dimensional case. A cylindrical phantom filled with a water solution of 131 I containing a region of "cold" spheres as well as a uniform solution (without any spheres) was used to perform algorithm evaluation. The reconstructed images obtained by using four different of methods system matrix computation were compared with those achieved using reconstruction software implemented in the gamma camera. The contrast of the spheres and uniformity were compared for each reconstruction result and also with the ranges of those values formulated by the AAPM (American Association of Physicists in Medicine). The results show that the implementation of the OSEM (Ordered Subsets Expectation Maximization) algorithm with a one-dimensional fit to the Gaussian CDR (Collimator-Detector Response) function provides the best results in terms of adopted measures. However, the fit of the two-dimensional function also gives satisfactory results. Furthermore, the CDR function has the potential to be applied to a fully 3D OSEM implementation. The lack of the CDR in system matrix calculation results in a very noisy image that cannot be used for diagnostic purposes.

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“…Currently, this is often done using scintigraphic wholebody planar images. For a limited number of agents (mostly 131 I), radiation produced by the isotope can be used for imaging, but the images obtained with single photon emission computed tomography (SPECT) scanners are often of poor quality for a variety of reasons [2,3].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional positron emission tomography imaging with 124I and 86Y

Vandenberghe¹

2006

Nuclear Medicine Communications

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3-D PET images of 124I and 86Y have lower spatial resolution. For PET scanners used for humans the difference is not as important as for scanners used for animals. The limited positron decay fraction of both isotopes can be compensated by increasing the imaging time by a factor of 3-5 (same activity). A short coincidence window limits the contamination from other decay modes. Good energy resolution allows setting a selective upper energy threshold to limit the effect of spurious coincidences. With an appropriate setting of the energy window it should be possible to obtain good image quality in a relatively short time because of the high sensitivity of 3-D PET scanners.

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Monte Carlo Modeling of Gamma Cameras for I-131 Imaging in Targeted Radiotherapy

Cited by 51 publications

References 13 publications

TestDose: a SPECT image generator for clinical dosimetry studies

TestDose: a SPECT image generator for clinical dosimetry studies

System matrix computation for iterative reconstruction algorithms in SPECT based on direct measurements

Three-dimensional positron emission tomography imaging with 124I and 86Y

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