Maximum-Likelihood Deconvolution in the Spatial and Spatial-Energy Domain for Events With Any Number of Interactions

Wang, Weiyi; Wahl, Christopher G.; Jaworski, Jason M.; He, Zhong

doi:10.1109/tns.2012.2183384

Cited by 15 publications

(6 citation statements)

References 8 publications

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“…[29]), which takes into account the different γ-ray spectra between neutron capture events in the sample and neutron-induced γ-ray backgrounds from the surroundings. Also very promising energy-imaging spectral deconvolution algorithms have been developed recently [30,31]. However, in this first demonstration stage, a more simple approach is followed using an analytic back-projection method [32] in combination with the fact, that the geometry of the set-up (sample position, size and distance to the i-TED detector) is known by construction.…”

Section: Compton Imaging Analysis Methodsmentioning

confidence: 99%

i-TED: A novel concept for high-sensitivity (n,γ) cross-section measurements

Domingo‐Pardo

2016

Nuclear Instruments and Methods in Physics Research Section A:

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Section: Compton Imaging Analysis Methodsmentioning

confidence: 99%

i-TED: A novel concept for high-sensitivity (n,γ) cross-section measurements

Domingo‐Pardo

2016

Nuclear Instruments and Methods in Physics Research Section A:

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“…In contrast to that work, we are interested in inferring the four-dimensional (spatial and spectral) PG emission distribution in a volume close to the telescope. As a consequence, some of the approximations done in Wang et al (2012) do not hold in our case. Notably, we cannot assume that the distance between the PG source and the 3-CT is much larger than the detector plane size, i.e.…”

Section: Introductionmentioning

confidence: 83%

“…In this work we are interested in developing a detailed analytical model for three interaction events, which does not rely on final gamma-ray absorption and provides a well defined expression for its associated sensitivity. A similar approach is followed in Wang et al (2012). In contrast to that work, we are interested in inferring the four-dimensional (spatial and spectral) PG emission distribution in a volume close to the telescope.…”

Section: Introductionmentioning

confidence: 99%

Image reconstruction for a multi-layer Compton telescope: an analytical model for three interaction events

Röser¹,

Muñoz²,

Barrientos³

et al. 2020

Phys. Med. Biol.

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Compton Cameras are electronically collimated photon imagers suitable for sub-MeV to few MeV gamma-ray detection. Such features are desirable to enable in vivo range verification in hadron therapy, through the detection of secondary Prompt Gammas. A major concern with this technique is the poor image quality obtained when the incoming gamma-ray energy is unknown. Compton Cameras with more than two detector planes (multi-layer Compton Cameras) have been proposed as a solution, given that these devices incorporate more signal sequences of interactions to the conventional two interaction events. In particular, three interaction events convey more spectral information as they allow inferring directly the incident gamma-ray energy. A three-layer Compton Telescope based on continuous Lanthanum (III) Bromide crystals coupled to Silicon Photomultipliers is being developed at the IRIS group of IFIC-Valencia. In a previous work we proposed a spectral reconstruction algorithm for two interaction events based on an analytical model for the formation of the signal. To fully exploit the capabilities of our prototype, we present here an extension of the model for three interaction events. Analytical expressions of the sensitivity and the System Matrix are derived and validated against Monte Carlo simulations. Implemented in a List Mode Maximum Likelihood Expectation Maximization algorithm, the proposed model allows us to obtain four-dimensional (energy and position) images by using exclusively three interaction events. We are able to recover the correct spectrum and spatial distribution of gamma-ray sources when ideal data are employed. However, the uncertainties associated to experimental measurements result in a degradation when real data from complex structures are employed. Incorrect estimation of the incident gamma-ray interaction positions, and missing deposited energy associated with escaping secondaries, have been identified as the causes of such degradation by means of a detailed Monte Carlo study. As expected, our current experimental resolution and efficiency to three interaction events prevents us from correctly recovering complex structures of radioactive sources. However, given the better spectral information conveyed by three interaction events, we expect an improvement of the image quality of conventional Compton imaging when including such events. In this regard, future development includes the incorporation of the model assessed in this work to the two interaction events model in order to allow using simultaneously two and three interaction events in the image reconstruction.

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“…Semiconductors can also attain finer resolution in positioning than even their own pixel dimensions by using the timing information, or the signal ratio of different electrodes (i.e., charge-sharing characteristics), which improves the angular resolution of the reconstructed Compton image. There have been several research investigations on Compton cameras using one or more CdZnTe detectors, mostly with detectors relying on single-crystal geometry [18]- [20].…”

Section: Introductionmentioning

confidence: 99%

Mini Compton Camera Based on an Array of Virtual Frisch-Grid CdZnTe Detectors

Lee

Bolotnikov

Lee

et al. 2016

IEEE Trans. Nucl. Sci.

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We constructed a mini Compton camera based on an array of CdZnTe detectors and assessed its spectral and imaging properties. The entire array consisted of Frisch-grid CdZnTe detectors, each with a size of mm. Since it is easier and more practical to grow small CdZnTe crystals rather than large monolithic ones, constructing a mosaic array of parallelepiped crystals can be an effective way to build a more efficient, large-volume detector. With the fully operational CdZnTe array, we measured the energy spectra for , ,-radiation sources; we also located these sources using a Compton imaging approach. Although the Compton camera was small enough to hand-carry, its intrinsic efficiency was several orders higher than those generated in previous researches using spatially separated arrays, because our camera measured the interactions inside the CZT detector array, wherein the detector elements were positioned very close to each other. The performance of our camera was compared with that based on a pixelated detector.

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Maximum-Likelihood Deconvolution in the Spatial and Spatial-Energy Domain for Events With Any Number of Interactions

Cited by 15 publications

References 8 publications

i-TED: A novel concept for high-sensitivity (n,γ) cross-section measurements

i-TED: A novel concept for high-sensitivity (n,γ) cross-section measurements

Image reconstruction for a multi-layer Compton telescope: an analytical model for three interaction events

Mini Compton Camera Based on an Array of Virtual Frisch-Grid CdZnTe Detectors

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