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17th International Workshop on Radiation Imaging Detectors

作者： Kolstein, M. Chmeissani, M. Barcelona Inst Sci & Technol IFAE Campus UAB E-08193 Bellaterra Barcelona Spain

The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 x 1 x 2mm(3) guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using beta(+)-gamma emitting isotopes with a Compton-PET scanner. When the beta(+) annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

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

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Experimental results of use of triple-energy X-ray beam with K-edge filter in multi-energy imaging

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JOURNAL OF INSTRUMENTATION 2016年第4期11卷 P04009-P04009页

作者： Kim, D. Lee, S. Jeon, P. -H. Eulji Univ Dept Radiol Sci 553 Sanseong Daero Songnam Gyeonggi South Korea Konyang Univ Dept Radiol Sci 158 Gwanjeodong Ro Daejoen South Korea Yonsei Univ Dept Radiol Sci 1 Yonseidae Gil Wonju Gangwon South Korea

Multi-energy imaging is useful for contrast enhancement of lesions, quantitative analysis of specific materials and material separation in the human body. Generally, dual-energy methods are applied to discriminating two materials, but this method cannot discriminate more than two materials. Photon-counting detectors provide spectral information from polyenergetic X-rays using multiple energy bins. In this work, we developed triple-energy X-ray beams using a filter with K-edge energy and applied them experimentally. The energy spectra of triple-energy X-ray beams were assessed by using a spectrometer. The designed triple-energy X-ray beams were validated by measuring quantitative evaluations with mean energy ratio (MER), contrast variation ratio (CVR) and exposure efficiency (EE). Then, triple-energy X-ray beams were used to extract density map of three materials, iodine (I), aluminum (Al) and polymethyl methacrylate (PMMA). The results of the thickness density maps obtained with the developed triple-energy X-ray beams were compared to those acquired using the photon-counting method. As a result, it was found experimentally that the proposed triple-energy X-ray beam technique can separate the three materials as well as the photon-counting method.

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

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A feasibility study for anatomical noise reduction in dual-energy chest digital tomosynthesis

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JOURNAL OF INSTRUMENTATION 2016年第1期11卷 P01016-P01016页

作者： Lee, D. Kim, Y. -s. Choi, S. Lee, H. Choi, S. Kim, H. -J. Yonsei Univ Coll Hlth Sci Dept Radiat Convergence Engn 1 Yonseidae Gil Wonju 220710 Gangwon South Korea Yonsei Univ Dept Radiol Sci 1 Yonseidae Gil Wonju 220710 Gangwon South Korea Yonsei Univ Res Inst Hlth Sci 1 Yonseidae Gil Wonju 220710 Gangwon South Korea

Lung cancer is the leading cause of cancer death worldwide. Thus, early diagnosis is of considerable importance. For early screening of lung cancer, computed tomography (CT) has been used as the gold standard. Chest digital tomosynthesis (CDT) is a recently introduced modality for lung cancer screening with a relatively low radiation dose compared to CT. The dual energy material decomposition method has been proposed for better detection of pulmonary nodules by means of reducing anatomical noise. In this study, the possibility of material decomposition in CDT was tested by both a simulation study and an experimental study using a CDT prototype. The Geant4 application for tomographic emission (GATE) v6 and tungsten anode spectral model using interpolating polynomials (TASMIP) codes were used for the simulation study to create simulated phantom shapes consisting of five inner cylinders filled with different densities of bone and airequivalent materials. Furthermore, the CDT prototype system and human phantom chest were used for the experimental study. CDT scan in both the simulation and experimental studies was performed with linear movement and 21 projection images were obtained over a 30 degree angular range with a 1.5 degree angular interval. To obtain materialselective images, a projectionbased energy subtraction technique was applied to high and low energy images. The resultant simulation images showed that dual-energy reconstruction could achieve an approximately 32% higher contrast to noise ratio (CNR) in images and the difference in CNR value according to bone density was significant compared to single energy CDT. Additionally, image artifacts were effectively corrected in dual energy CDT simulation studies. Likewise the experimental study with dual energy produced clear images of lung fields and bone structure by removing unnecessary anatomical structures. Dual energy tomosynthesis is a new technique;therefore, there is little guidance regarding its integrati

关键词： X-ray radiography and digital radiography (DR) computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided diagnosis medical-image reconstruction methods and algorithms, computer-aided software

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Improvement of material decomposition and image quality in dual-energy radiography by reducing image noise

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JOURNAL OF INSTRUMENTATION 2016年第8期11卷 T08003-T08003页

作者： Lee, D. Kim, Y. -s. Choi, S. Lee, H. Choi, S. Jo, B. D. Jeon, P. -H. Kim, H. Kim, D. Kim, H. Kim, H. -J. Yonsei Univ Coll Hlth Sci Dept Radiat Convergence Engn 1 Yonseidae Gil Wonju 220710 Gangwon South Korea Yonsei Univ Dept Radiol Sci 1 Yonseidae Gil Wonju 220710 Gangwon South Korea Yonsei Univ Res Inst Hlth Sci 1 Yonseidae Gil Wonju 220710 Gangwon South Korea

Although digital radiography has been widely used for screening human anatomical structures in clinical situations, it has several limitations due to anatomical overlapping. To resolve this problem, dual-energy imaging techniques, which provide a method for decomposing overlying anatomical structures, have been suggested as alternative imaging techniques. Previous studies have reported several dual-energy techniques, each resulting in different image qualities. In this study, we compared three dual-energy techniques: simple log subtraction (SLS), simple smoothing of a high-energy image (SSH), and anti-correlated noise reduction (ACNR) with respect to material thickness quantification and image quality. To evaluate dual-energy radiography, we conducted Monte Carlo simulation and experimental phantom studies. The Geant 4 Application for Tomographic Emission (GATE) v 6.0 and tungsten anode spectral model using interpolation polynomials (TASMIP) codes were used for simulation studies and digital radiography, and human chest phantoms were used for experimental studies. The results of the simulation study showed improved image contrast-to-noise ratio (CNR) and coefficient of variation (COV) values and bone thickness estimation accuracy by applying the ACNR and SSH methods. Furthermore, the chest phantom images showed better image quality with the SSH and ACNR methods compared to the SLS method. In particular, the bone texture characteristics were well-described by applying the SSH and ACNR methods. In conclusion, the SSH and ACNR methods improved the accuracy of material quantification and image quality in dual-energy radiography compared to SLS. Our results can contribute to better diagnostic capabilities of dual-energy images and accurate material quantification in various clinical situations.

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

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Online image corrections applied to a dedicated breast PET

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JOURNAL OF INSTRUMENTATION 2016年第3期11卷 C03035-C03035页

作者： Moliner, L. Gonzalez, A. J. Correcher, C. Benlloch, J. M. Univ Politecn Valencia CSIC Inst Instrumentat Mol Imaging I3M Cami Vera S-N E-46022 Valencia Spain Prince Felipe Res Ctr Oncovis Eduardo Primo Yufera 3 Valencia Spain

In this work, we present the online implementation of attenuation, scatter and random corrections using the LMEM algorithm for the dedicated breast PET named MAMMI. The attenuation correction is based on image segmentation, the random correction is derived from the rate estimation of single photon events and the scatter correction is determined by the dual energy window method. These three corrections are estimated and implemented in the reconstruction process without almost increasing the reconstruction time. The image quality is evaluated in terms of image uniformity and contrast using the reconstructed images of two custom-designed phantoms. When we apply the three corrections, the measured uniformity in the whole field of view is (10 +/- 1)% compared to (17 +/- 1)% without corrections. The adapted recovery contrast coefficients (normalized to 1) are approximately (0.80 +/- 0.02) in hot areas, improving the value of (0.66 +/- 0.07) obtained without corrections. The reconstruction processing time is also studied, finding an increment of around 7% when the three corrections are simultaneously included. Finally, 25 breast image datasets are also analyzed. The average acquisition time per patient is around 1200 seconds and the reconstruction times with corrections vary from 100 to 400 seconds using (1x1x1) mm(3) voxel size and from 300 to 1800 seconds using (0.5x0.5x0.5) mm(3) voxel size. These reconstructions are performed with a virtual pixel size of (1.6x1.6) mm(2) and twelve iterations.

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

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reconstruction method for grating-based x-ray phase-contrast images without knowledge of the grating positions

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JOURNAL OF INSTRUMENTATION 2015年第12期10卷 P12017-P12017页

作者： Pelzer, G. Rieger, J. Hauke, C. Horn, F. Michel, T. Seifert, M. Anton, G. Univ Erlangen Nurnberg Erlangen Ctr Astroparticle Phys Erwin Rommel Str 1 D-91058 Erlangen Germany

To retrieve the phase information of x-rays using a Talbot-Lau interferometer, the knowledge of the grating positions is mandatory. Transferring the interferometer technique from the laboratory to a conventional x-ray imaging system, this requirement is no longer guaranteed. This is due to distortions and vibrations which are coupled into the interferometer. Therefore, we applied a principal-component analysis to Talbot-Lau x-ray phase-contrast data. In experiments we compared this alternative approach for image reconstruction to the conventional procedure. As a result, a superior robustness of the principal-component analysis against imperfect phase-stepping data was found. Furthermore, using the proposed method, the reconstruction of x-ray phase-contrast images from randomly distributed phase-step positions is possible.

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

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Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

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JOURNAL OF INSTRUMENTATION 2016年第1期11卷

作者： Kolstein, M. Chmeissani, M. Barcelona Inst Sci & Technol IFAE Campus UAB E-08193 Bellaterra Barcelona Spain

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

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Development of a novel gamma probe for detecting radiation direction

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JOURNAL OF INSTRUMENTATION 2016年第1期11卷 C01002-C01002页

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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Development of a proton Computed Tomography detector system

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JOURNAL OF INSTRUMENTATION 2016年第2期11卷 C02012-C02012页

作者： Naimuddin, Md. Coutrakon, G. Blazey, G. Boi, S. Dyshkant, A. Erdelyi, B. Hedin, D. Johnson, E. Krider, J. Rukalin, V. Uzunyan, S. A. Zutshi, V. Fordt, R. Sellberg, G. Rauch, J. E. Roman, M. Rubinov, P. Wilson, P. Univ Delhi Dept Phys & Astrophys Delhi 110007 India No Illinois Univ Dept Phys De Kalb IL 60115 USA Fermilab Natl Accelerator Lab POB 500 Batavia IL 60510 USA

computer tomography is one of the most promising new methods to image abnormal tissues inside the human body. Tomography is also used to position the patient accurately before radiation therapy. Hadron therapy for treating cancer has become one of the most advantegeous and safe options. In order to fully utilize the advantages of hadron therapy, there is a necessity of performing radiography with hadrons as well. In this paper we present the development of a proton computed tomography system. Our second-generation proton tomography system consists of two upstream and two downstream trackers made up of fibers as active material and a range detector consisting of plastic scintillators. We present details of the detector system, readout electronics, and data acquisition system as well as the commissioning of the entire system. We also present preliminary results from the test beam of the range detector.

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

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

Preliminary evaluation of a monolithic detector module for i...

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16th International Workshop on Radiation Imaging Detectors

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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