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Integrated ultrasound and gamma imaging probe for medical diagnosis

JOURNAL OF INSTRUMENTATION 2016年第3期11卷 C03037-C03037页

作者： Pani, R. Pellegrini, R. Cinti, M. N. Polito, C. Orlandi, C. Fabbri, A. De Vincentis, G. Univ Roma La Sapienza Dept Sci & Med & Surg Biotechnol Rome Italy Ist Nazl Fis Nucl Roma Sect 1 Rome Italy Univ Roma La Sapienza Dept Mol Med Rome Italy Univ Roma La Sapienza SAIMLAL Dept Doctorate Sch Biol & Mol Med Morphogenesis & Tissue EngnCurriculum Cell & Tis Rome Italy Bambino Gesu Pediat Hosp Dept Med Phys Enterprise Risk Management Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Anat Pathol Rome Italy

In the last few years, integrated multi-modality systems have been developed, aimed at improving the accuracy of medical diagnosis correlating information from different imaging techniques. In this contest, a novel dual modality probe is proposed, based on an ultrasound detector integrated with a small field of view single photon emission gamma camera. The probe, dedicated to visualize small organs or tissues located at short depths, performs dual modality images and permits to correlate morphological and functional information. The small field of view gamma camera consists of a continuous NaI:Tl scintillation crystal coupled with two multi-anode photomultiplier tubes. Both detectors were characterized in terms of position linearity and spatial resolution performances in order to guarantee the spatial correspondence between the ultrasound and the gamma images. Finally, dual-modality images of custom phantoms are obtained highlighting the good co-registration between ultrasound and gamma images, in terms of geometry and image processing, as a consequence of calibration procedures.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software Multi-modality systems

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Combined SRCT & FXCT - The next steps

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JOURNAL OF INSTRUMENTATION 2016年第3期11卷 C03048-C03048页

作者： Hall, C. Acres, R. G. Winnett, A. Wang, F. Australian Synchrotron Imaging & Med Beamline Clayton Vic 3168 Australia Swinburne Univ Dept Chem & Biotechnol Hawthorn Vic 3122 Australia

One of the goals in developing synchrotron radiation x-ray computed tomography (SRCT) for biomedical specimens, is allowing particular tissues and cell types to be marked in the images. This is equivalent to the staining in histology, which enables researchers to visualise and measure tissue structure and biochemical processes within the specimen. Some progress in this direction for SRCT is being made, using a variety of contrast agents that alter the natural x-ray attenuation of the marked tissue [1]. However there are limits to the usefulness of these attenuation altering techniques. Often high concentrations of potentially disruptive chemicals are required with reduced compatibility for in-vivo studies. Another image highlighting technique which might prove more sensitive is x-ray fluorescence imaging. In this case usually endogenous elemental markers are visualised. We would like to develop a lower resolution, but wider field of view means of three-dimensional (3-D) fluorescence imaging compatible with SRCT. We have previously proposed a technique in which x-ray fluorescence CT (FXCT) and SRCT data can be collected simultaneously [3]. This work resulted in proof of concept modelling, and a simple experiment test system. We show data here which demonstrate a two-dimensional (2-D) reconstruction of an iodine fluorescence map from a phantom. Measurements were performed with a fixed beam modulating mask using the Imaging and medical beam line (IMBL) at the Australian Synchrotron. Fluorescence data was obtained during a CT scan using a single point detector, while transmission data was simultaneously collected using an area detector. A maximum likelihood expectation maximisation (MLEM) iterative algorithm was used to reconstruct the fluorescence map. We report on technique development and now believe compressive sensing (CS) imaging techniques suit SRCT and may overcome the issues encountered so far in combining SRCT and FXCT.

关键词： X-ray fluorescence (XRF) systems medical-image reconstruction methods and algorithms, computer-aided software Simulation methods and programs

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Simulation of novel scintillator crystals for brain PET

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JOURNAL OF INSTRUMENTATION 2020年第5期15卷

作者： Ozsahin, I. Ozsahin, D. Uzun Makarov, P. A. Musa, M. S. Mok, G. S. P. Univ Macau Fac Sci & Technol Dept Elect & Comp Engn Biomed Imaging Lab Macau Peoples R China Near East Univ Fac Engn Dept Biomed Engn Mersin 10 TRNC TR-99138 Nicosia Turkey Near East Univ DESAM Inst Mersin 10 TRNC TR-99138 Nicosia Turkey Near East Univ Innovat & Informat Technol Ctr Mersin 10 TRNC TR-99138 Nicosia Turkey Univ Macau Fac Hlth Sci Macau Peoples R China

In the last decade, different positron emission tomography (PET) crystals have been proposed for brain PET detectors. Brain PET cameras with restricted field of view to a smaller size to cover the brain can both exhibit significantly higher performance and lower the cost when compared to conventional whole-body PET scanners. The existing designs based on scintillation crystals employ the most commonly known materials such as lutetium oxyorthosilicate and bismuth germanate. This is due to their relatively good parameters such as high light yield and density. The main drawback of using scintillation crystals is that they have a modest energy resolution. In this study, a brain PET scanner was designed and simulated using a Geant4 Application for Tomographic Emission (GATE) toolkit. The performances of five crystals, namely strontium hafnate, gadolinium aluminium gallium garnet, gadolinium yttrium gallium aluminium garnet, gadolinium lutetium gallium aluminium garnet, and lutetium oxyorthosilicate for comparison, were evaluated in terms of sensitivity, spatial resolution, and count rate. The performance evaluation results showed that among the suggested scintillators, strontium hafnate can be considered as a promising alternative detector for high performance brain PET systems.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided diagnosis medical-image reconstruction methods and algorithms, computer-aided software Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators)

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Development of correction methods for variable pinhole single-photon emission computed tomography

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JOURNAL OF INSTRUMENTATION 2016年第2期11卷 C02060-C02060页

作者： Bae, S. Bae, J. Lee, H. Lee, K. Korea Univ Dept Bioconvergence Engn 145 Anam Ro Seoul South Korea Korea Univ Res Inst Global Hlth Technol 145 Anam Ro Seoul South Korea Korea Univ Sch Biomed Engn 145 Anam Ro Seoul South Korea

We propose a novel pinhole collimator in which the pinhole shape can be changed in real-time, and a new single-photon emission computed tomography (SPECT) system that utilizes this variable pinhole (VP) collimator. The acceptance angle and distance between the collimator and the object of VP SPECT are varied so that the optimum value of the region-of-interest (ROI) can be obtained for each rotation angle. Because of these geometrical variations, new correction methods are required for image reconstruction. In this study, we developed two correction methods. The first is the sensitivity-correction algorithm, which minimizes the variation of a system matrix caused by varying the acceptance angle for each rotation angle. The second is the acquisition-time-correction method, which reduces the variation of uniformity caused by varying the distance between the collimator and the object for each rotation angle. A 3D maximum likelihood expectation maximization (MLEM) algorithm was applied to image reconstruction, and two digital phantoms were studied to evaluate the resolution and sensitivity of the images obtained using the proposed methods. The images obtained by using the proposed correction methods show higher uniformity and resolution than those obtained without using these methods. In particular, the results of the resolution phantom study show that hot rods (0.8-mm-diameter) can be clearly distinguished using the proposed correction methods. A quantitative analysis of the ROI phantom revealed that the mean square error (MSE) was 0.42 without the acquisition-time-correction method, and 0.04 with the acquisition-time-correction method. The MSEs of the resolution phantom without and with the acquisition-time-correction method were calculated as 55.14 and 14.69, respectively.

关键词： Data processing methods Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software

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Position algorithm for monolithic scintillation crystals based on charge projection readout

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JOURNAL OF INSTRUMENTATION 2016年第1期11卷 C01061-C01061页

作者： Pani, R. Bettiol, M. Preziosi, E. Cinti, M. N. Borrazzo, C. Pellegrini, R. Di Castro, E. Fabbri, A. Univ Roma La Sapienza Dept Sci & Med & Surg Biotechnol Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Dept Mol Med Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Morphofunct Sci Biophys Doctorate Sch Biol & Mol Med SAIMLAL Dept Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Post Grad Sch Med Phys Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Pathol Piazzale Aldo Moro 5 I-00185 Rome Italy

Nuclear medicine imaging devices commonly use multi-element photo detection systems, composed of an array of N x N elements, each one providing an individual signal. Many strategies have been developed to reduce the number of readout channels, one of the main approaches is the Rows and Columns (R/C) projection logic. In this paper we proposed a modified version of Raised To the Power (RTP) algorithm adapted to R/C logic. In order to validate its efficiency a linear scanning irradiation on two 49 x 49 mm(2) LaBr3:Ce (0.5%) crystals with different thickness (4 mm and 10 mm) was carried out. Imaging performance analysis was made in terms of position linearity, Field-of-View (FoV) enlargement and spatial resolution. Imaging results from Anger Logic, RTP algorithm based on single element readout and RTP algorithm based on R/C readout were compared. A notable advantage of using RTP algorithms instead of Anger Logic was found: the FoV widens from about 30% to more than 70% of the detector area whereas the spatial resolution is highly improved, especially for off-center interactions, both for 4 mm-thick and 10 mm-thick crystals. Furthermore, imaging performance with the R/C readout is just slightly different from the single element one (FoV reduction less than 7% and SR worsening less than 10%). The R/C adapted RTP algorithm opens doors to high imaging performance with a substantial reduction of complexity and cost in the readout electronics.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software

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Signal to Noise Ratio optimization for extended sources with a new kind of MURA masks

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JOURNAL OF INSTRUMENTATION 2020年第1期15卷

作者： Kaissas, I. Papadimitropoulos, C. Clouvas, A. Potiriadis, C. Lambropoulos, C. P. Greek Atom Energy Commiss Patriarchou Grigoriou & Neapoleos Attiki 15341 Greece Aristotle Univ Thessaloniki Sch Elect & Comp Engn Univ Campus Thessaloniki 54124 Greece Natl & Kapodistrian Univ Athens Athens Greece

Using coded aperture, for localization of radioactive hot-spots, results in enhanced efficiency and under certain configurations wide Field of View (FOV). We present a coded aperture assembly technique which can be restructured easily, as well as the reduction of the intrinsic noise of coded apertures constructed with this technique, when they localize spatially extended gamma-emitters. Specifically, Modified-Uniformly-Redundant-Array (MURA) coded apertures are structured by embedding lead spheres in a matrix of positions machined inside a transparent medium such as acrylic glass, resulting in an advantageous transparent to opaque area ratio and thus an improved detection efficiency. This configuration also induces a systematic, element-wise, noise on the Point-Spread-Function (PSF) of the correlation matrix. When imaging with these apertures extended hot-spots, a penumbra phenomenon occurrs and reduces this intrinsic noise, in the way a kernel filter does. Fast-Fourier-Transform (FFT) is used to analyze the effect of this phenomenon on the correlation matrix and to explain the maximization of its Signal-to-Noise Ratio (SNR) for certain extent of the hot-spots. Simulations have been used for the detailed study of the SNR dependence on the dimensions of the hot-spot, while experiments with two Tc-99m cylindrical sources with 11mm and 24mm diameter, respectively and 1.5MBq activity each, confirm the reduction of the intrinsic noise. The results define the way of optimization of the imaging setup for the detection of extended hot-spots. Such an optimization could be useful for example in the case of lymph nodes or thyroid remnant imaging in nuclear medicine. Finally, we propose a kernel filter, derived by the Auto-Correlation-Function (ACF), to be applied on PSFs with high intrinsic noise, in order to eliminate it.

关键词： image filtering Intra-operative probes medical-image reconstruction methods and algorithms, computer-aided software Search for radioactive and fissile materials

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Development of correction methods for variable pinhole single-photon emission computed tomography

Development of correction methods for variable pinhole singl...

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17th International Workshop on Radiation Imaging Detectors

关键词： Data processing methods Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software

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Development of a novel gamma probe for detecting radiation direction

Development of a novel gamma probe for detecting radiation d...

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17th International Workshop on Radiation Imaging Detectors

作者： Pani, R. Pellegrini, R. Cinti, M. N. Longo, M. Donnarumma, R. D'Alessio, A. Borrazzo, C. Pergola, A. Ridolfi, S. De Vincentis, G. Univ Roma La Sapienza Dept Sci & Med & Surg Biotechnol Piazzale Aldo Moro 5 I-00185 Rome Italy Ist Nazl Fis Nucl Sez Roma Piazzale Aldo Moro 2 I-00185 Roma Rome Italy Univ Roma La Sapienza Dept Mol Med Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Postgrad Sch Med Phys Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Piazzale Aldo Moro 5 I-00185 Rome Italy Ars Mensurae Via Vincenzo Comparini 101 I-00188 Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Anat Pathol Piazzale Aldo Moro 5 I-00185 Rome Italy

Spatial localization of radioactive sources is currently a main issue interesting different fields, including nuclear industry, homeland security as well as medical imaging. It is currently achieved using different systems, but the development of technologies for detecting and characterizing radiation is becoming important especially in medical imaging. In this latter field, radiation detection probes have long been used to guide surgery, thanks to their ability to localize and quantify radiopharmaceutical uptake even deep in tissue. Radiolabelled colloid is injected into, or near to, the tumor and the surgeon uses a hand-held radiation detector, the gamma probe, to identify lymph nodes with radiopharmaceutical uptkake. The present work refers to a novel scintigraphic goniometric probe to identify gamma radiation and its direction. The probe incorporates several scintillation crystals joined together in a particular configuration to provide data related to the position of a gamma source. The main technical characteristics of the gamma locator prototype, i.e. sensitivity, spatial resolution and detection efficiency, are investigated. Moreover, the development of a specific procedure applied to the images permits to retrieve the source position with high precision with respect to the currently used gamma probes. The presented device shows a high sensitivity and efficiency to identify gamma radiation taking a short time (from 30 to 60 s). Even though it was designed for applications in radio-guided surgery, it could be used for other purposes, as for example homeland security.

关键词： Intra-operative probes Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software

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Simulation of novel scintillator crystals for brain PET

Simulation of novel scintillator crystals for brain PET

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15th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD)

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Evaluation of list-mode ordered subset expectation maximization image reconstruction for pixelated solid-state compton gamma camera with large number of channels

Evaluation of list-mode ordered subset expectation maximizat...

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15th International Workshop on Radiation Imaging Detectors

作者： Kolstein, M. De Lorenzo, G. Chmeissani, M. Univ Autonoma Barcelona IFAE E-08193 Bellaterra Spain

The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated solid-state technology for nuclear medicine applications. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 10(6)). For Compton camera, especially with a large number of readout channels, image reconstruction presents a big challenge. In this work, results are presented for the List-Mode Ordered Subset Expectation Maximization (LM-OSEM) image reconstruction algorithm on simulated data with the VIP Compton camera design. For the simulation, all realistic contributions to the spatial resolution are taken into account, including the Doppler broadening effect. The results show that even with a straight-forward implementation of LM-OSEM, good images can be obtained for the proposed Compton camera design. Results are shown for various phantoms, including extended sources and with a distance between the field of view and the first detector plane equal to 100 mm which corresponds to a realistic nuclear medicine environment.

关键词： image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software Compton imaging

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