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Preliminary evaluation of a monolithic detector module for integrated PET/MRI scanner with high spatial resolution

JOURNAL OF INSTRUMENTATION 2015年第6期10卷 2015 JINST 10 C06006-2015 JINST 10 C06006页

作者： Pani, R. Gonzalez, A. J. Bettiol, M. Fabbri, A. Cinti, M. N. Preziosi, E. Borrazzo, C. Conde, P. Pellegrini, R. Di Castro, E. Majewski, S. Univ Roma La Sapienza Dept Mol Med I-00185 Rome Italy CSIC I3M Valencia 46022 Spain Univ Roma La Sapienza Postgrad Sch Med Phys I-00185 Rome Italy Univ Roma La Sapienza SAIMLAL Dept Doctorate Sch Biol & Mol Med Morphofunct Sci Biophys I-00185 Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Pathol I-00185 Rome Italy W Virginia Univ Dept Radiol Ctr Adv Imaging Morgantown WV 26506 USA

The proposal of Mindview European Project concerns with the development of a very high resolution and high efficiency brain dedicated PET scanner simultaneously working with a Magnetic Resonance scanner, that expects to visualize neurotransmitter pathways and their disruptions in the quest to better diagnose schizophrenia. On behalf of this project, we propose a low cost PET module for the first prototype, based on monolithic crystals, suitable to be integrated with a head Radio Frequency (RF) coil. The aim of the suggested module is to achieve high performances in terms of efficiency, planar spatial resolution (expected about 1 mm) and discrimination of gamma Depth Of Interaction (DOI) in order to reduce the parallax error. Our preliminary results are very promising: a DOI resolution of about 3 mm, a spatial resolution ranging from about 1 to 1.5 mm and a good position linearity.

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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Evaluation of the Intel Xeon Phi Co-processor to accelerate the sensitivity map calculation for PET imaging

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JOURNAL OF INSTRUMENTATION 2015年第7期10卷

作者： Dey, T. Rodrigue, P. Philips Res Oncol Solut NL-5656 AE Eindhoven Netherlands

We aim to evaluate the Intel Xeon Phi coprocessor for acceleration of 3D Positron Emission Tomography (PET) image reconstruction. We focus on the sensitivity map calculation as one computational intensive part of PET image reconstruction, since it is a promising candidate for acceleration with the Many Integrated Core (MIC) architecture of the Xeon Phi. The computation of the voxels in the field of view (FoV) can be done in parallel and the 10(3) to 10(4) samples needed to calculate the detection probability of each voxel can take advantage of vectorization. We use the ray tracing kernels of the Embree project to calculate the hit points of the sample rays with the detector and in a second step the sum of the radiological path taking into account attenuation is determined. The core components are implemented using the Intel single instruction multiple data compiler (ISPC) to enable a portable implementation showing efficient vectorization either on the Xeon Phi and the Host platform. On the Xeon Phi, the calculation of the radiological path is also implemented in hardware specific intrinsic instructions (so-called 'intrinsics') to allow manually-optimized vectorization. For parallelization either OpenMP and ISPC tasking (based on pthreads) are evaluated. Our implementation achieved a scalability factor of 0.90 on the Xeon Phi coprocessor (model 5110P) with 60 cores at 1 GHz. Only minor differences were found between parallelization with OpenMP and the ISPC tasking feature. The implementation using intrinsics was found to be about 12% faster than the portable ISPC version. With this version, a speedup of 1.43 was achieved on the Xeon Phi coprocessor compared to the host system (HP SL250s Gen8) equipped with two Xeon (E5-2670) CPUs, with 8 cores at 2.6 to 3.3 GHz each. Using a second Xeon Phi card the speedup could be further increased to 2.77. No significant differences were found between the results of the different Xeon Phi and the Host implementations. The examina

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software Computing (architecture, farms, GRID for recording, storage, archiving, and distribution of data)

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A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect: a simulation study

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JOURNAL OF INSTRUMENTATION 2014年第10期9卷 P10004-P10004页

作者： Yang, Renhuan Song, Aiguo Li, Xiao Dong Lu, Yang Yan, Ruqiang Xu, Baoguo Li, Xu Jinan Univ Coll Informat & Technol Guangzhou 510632 Guangdong Peoples R China Southeast Univ Sch Instrument Sci & Engn Nanjing 210096 Jiangsu Peoples R China Johns Hopkins Univ Dept Radiol & Radiol Sci Baltimore MD 21205 USA

A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect by deconvolution is proposed for noninvasive imaging of biological tissue. Compared with ultrasound current source density imaging, ultrasound Joule heat density tomography doesn't require any priori knowledge of conductivity distribution and lead fields, so it can gain better imaging result, more adaptive to environment and with wider application scope. For a general 3D volume conductor with broadly distributed current density field, in the AE equation the ultrasound pressure can't simply be separated from the 3D integration, so it is not a common modulation and basebanding (heterodyning) method is no longer suitable to separate Joule heat density from the AE signals. In the proposed method the measurement signal is viewed as the output of Joule heat density convolving with ultrasound wave. As a result, the internal 3D Joule heat density can be reconstructed by means of Wiener deconvolution. A series of computer simulations set for breast cancer imaging applications, with consideration of ultrasound beam diameter, noise level, conductivity contrast, position dependency and size of simulated tumors, have been conducted to evaluate the feasibility and performance of the proposed reconstruction method. The computer simulation results demonstrate that high spatial resolution 3D ultrasound Joule heat density imaging is feasible using the proposed method, and it has potential applications to breast cancer detection and imaging of other organs.

关键词： image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided diagnosis Multi-modality systems medical-image reconstruction methods and algorithms, computer-aided software

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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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Sub-millimeter nuclear medical imaging with high sensitivity in positron emission tomography using β⁺γ coincidences

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JOURNAL OF INSTRUMENTATION 2014年第1期9卷 P01008-P01008页

作者： Lang, C. Habs, D. Parodi, K. Thirolf, P. G. Univ Munich Fak Phys LS Med Phys D-85748 Garching Germany Max Planck Inst Quantum Opt D-84748 Garching Germany

We present a nuclear medical imaging technique, employing triple-g trajectory intersections from beta(+)-gamma coincidences, able to reach sub-millimeter spatial resolution in 3 dimensions with a reduced requirement of reconstructed intersections per voxel compared to a conventional PET reconstruction analysis. This 'gamma-PET' technique draws on specific beta(+)-decaying isotopes, simultaneously emitting an additional photon. Exploiting the triple coincidence between the positron annihilation and the third photon, it is possible to separate the reconstructed 'true' events from background. In order to characterize this technique, Monte-Carlo simulations and image reconstructions have been performed. The achievable spatial resolution has been found to reach ca. 0.4 mm (FWHM) in each direction for the visualization of a Na-22 point source. Only 40 intersections are sufficient for a reliable sub-millimeter image reconstruction of a point source embedded in a scattering volume of water inside a voxel volume of about 1 mm(3) ('high-resolution mode'). Moreover, starting with an injected activity of 400 MBq for Br-76, the same number of only about 40 reconstructed intersections are needed in case of a larger voxel volume of 2 x 2 x 3 mm(3) ('high-sensitivity mode'). Requiring such a low number of reconstructed events significantly reduces the required acquisition time for image reconstruction (in the above case to about 140 s) and thus may open up the perspective for a quasi real-time imaging.

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

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Simulation and evaluation of a high resolution VIP PEM system with a dedicated LM-OSEM algorithm

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JOURNAL OF INSTRUMENTATION 2014年第5期9卷 C05011-C05011页

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

Over the last two decades there have been a growing number of designs for positron emission tomography (PET) cameras optimized to image the breast. These devices, commonly known as positron emission mammography (PEM) cameras allow much more spatial resolution by putting the photon detectors directly on the breast. PEM cameras have a compact geometry with a restricted field of view (FOV) thus exhibiting higher performance and lower cost than large whole body PET scanners. Typical PEM designs are based on scintillators such as bismuth germanate (BGO), lutetium oxorthosilicate (LSO) or lutetium yttrium orthosicilate (LYSO), and characterized by large parallax error due to deficiency of the depth of interaction (DOI) information from crystals. In the case of parallel geometry PEM, large parallax error results in poor image resolution along the vertical axis. In the framework of the Voxel Imaging PET (VIP) pathfinder project, we propose a high resolution PEM scanner based on pixelated solid-state CdTe detectors. The pixel PEM device with a millimeter-size pixel pitch provides an excellent spatial resolution in all directions 8 times better than standard commercial devices with a point spread function (PSF) of 1mm full width at half maximum (FWHM) and excellent energy resolution of down to 1.6% FWHM at 511 keV photons at room temperature. The system is capable to detect down to 1mm diameter hot spheres in warm background.

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

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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

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JOURNAL OF INSTRUMENTATION 2014年第4期9卷

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

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

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Analysis of femur head microstructure in ovariectomized rats

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JOURNAL OF INSTRUMENTATION 2013年第7期8卷 C07007-C07007页

作者： Andrade, C. B. V. Nogueira, L. P. Salata, C. da Silva, C. M. Ferreira-Machado, S. C. de Almeida, C. E. Almeida, A. P. Colaco, M. V. Alessio, R. C. P. V. Braz, D. Tromba, G. Barroso, R. C. Univ Estado Rio de Janeiro Lab Ciencias Radiol BR-20550011 Rio De Janeiro Brazil Univ Estado Rio de Janeiro Lab Fis Med BR-20550011 Rio De Janeiro Brazil Univ Fed Fluminense Dept Biol Geral Niteroi RJ Brazil COPPE Univ Fed Rio de Janeiro BR-21945970 Rio De Janeiro Brazil Sincrotrone Trieste ScpA I-34012 Trieste Italy

It is well accepted that rat ovariectomy (OVX) is a model of estrogen deficiency. OVX played a very important role in the initiating and developing of osteoporosis and it has been shown to be a major risk factor for the development of postmenopausal osteoporosis in women. In this work we used synchrotron radiation computed microtomography to investigate the skeletal effects in femoral head of femaleWistar rats after bilateral ovariectomy surgery. The CT system was set up at the SYRMEP beamline in the synchrotron radiation facility ELETTRA (Trieste, Italy). Micro-CT images provided 3D information on precise trabecular microstructure by the reconstruction of multiple 2D images with almost 2 mu m resolution. Our aim was to use histomorphometric analysis to reveal the effect of OVX on the three-dimensional (3D) trabecular bone microarchitecture. Evaluated morphometric parameters were trabecular bone volume-tissue volume ratio (BV/TV), trabecular number (Tb.N), trabecular separation (***) and trabecular thickness (***). OVX group presented noticeable reduction in the Tb.N and *** when compared with control group (P < 0.01). However, trabecular micro-CT parameters showed that BV/TV and *** were slightly lower in the OVX animals than that of the control group during the experimental period, which was not significantly different (P > 0.05). Our data may help to gain more insight into the potential mechanism of osteoporotic femoral head fractures.

关键词： computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided software

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Optimal contrast enhancement achieved by the synthetic method for bone and tissue separation based on a dual-energy radiographic system

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JOURNAL OF INSTRUMENTATION 2013年第07期8卷 P07009-P07009页

作者： Kim, D. -H. Lee, Y. -J. Jeon, P. -H. Jo, B. -D. Kim, H. -J. Yonsei Univ Dept Radiol Sci Wonju 220710 Gangwon South Korea Yonsei Univ Res Inst Hlth Sci Wonju 220710 Gangwon South Korea

In dual-energy digital radiography (DEDR), the energy subtraction and equivalent thickness methods have been used for detecting thorax lesions. However, the image contrast of the energy subtraction method is low in comparion with that of the equivalent thickness and synthetic methods. Therefore, we applied the equivalent thickness and synthetic methods to material separation to enhance the bone and tissue contrast, and these results were compared with the results of the energy subtraction method in a chest DEDR system. The purpose of this work was to evaluate the image quality of the energy subtraction, equivalent thickness, and synthetic methods. In the energy subtraction method, the optimal weighting factors were selected for bone and tissue visualization, respectively. The equivalent thickness was obtained with a calibration procedure by using combinations of aluminum and polymethyl methacrylate (PMMA) blocks. The synthetic images were acquired with the known equation from the results of the equivalent thickness method. According to these results, the contrast-to-noise-ratio (CNR) values using the equivalent thickness and synthetic methods were improved than those obtained with the energy subtraction method in both aluminum and PMMA enhancement trial. In a cylindrical phantom study, the equivalent thickness and the synthetic method improved the contrast better than energy subtraction method. The synthetic method supplements the air shadows shown in the equivalent thickness method. We compared the enhanced images of bone and tissue with the energy subtraction, equivalent thickness, and synthetic methods. Our results showed that the effects of the synthetic method can improve the image contrast on both bone and tissue and overcome the bone shadows in tissue images in a DEDR system.

关键词： X-ray radiography and digital radiography (DR) medical-image reconstruction methods and algorithms, computer-aided software

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Study of position reconstruction of a LaBr3: Ce continuous scintillation crystal for medical applications

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JOURNAL OF INSTRUMENTATION 2013年第12期8卷 P12010-P12010页

作者： Fabbri, A. Sacco, D. Bennati, P. Baroncelli, A. Galasso, M. Cinti, M. N. Pellegrini, R. Pani, R. Cencelli, V. O. Univ Rome Roma Tre Dept Phys Rome Italy Univ Roma La Sapienza Dept Mol Med I-00185 Rome Italy Ist Nazl Fis Nucl Sez Roma Uno Rome Italy Ist Nazl Fis Nucl Sez Roma Tre Rome Italy INAIL Rome Italy

Many modern molecular imaging techniques, based on radiopharmaceuticals, can take advantage of sophisticated devices but are still based on the scintillation detector mechanism proposed by Anger. These devices can perform with millimeter spatial resolution and high detection efficiency, but the final performance is strongly affected by the algorithm used for the scintillation position detection. In this work, a detailed comparison of the effect on the imaging performances of three new position detection algorithms, in terms of spatial resolution, detection linearity and useful Field of View is performed on a prototype gamma detector. The detector, built by the authors, is based on a continuous LaBr3: Ce scintillation crystal coupled to an Hamamatsu MA-PMT H8500 and a single anode readout electronics. The experimental data are obtained scanning the detector surface with a Tc99m collimated source (0.4mm f) at 1.5mm step. The overall imaging performances of the device are also tested by mean of a bar phantom. We conclude that the Anger-like algorithms give a 50% uFoV with a 1.30mm +/- 0.05mm spatial resolution while the proposed algorithms give a 80% uFoV and 1.10mm +/- 0.06mm spatial resolution.

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

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