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19th International Workshop on Radiation Imaging Detectors (IWORID)

作者： Trojanova, E. Jakubek, J. Turecek, D. Sykora, V. Francova, P. Kolarova, V. Sefc, L. ADVACAM Sro U Pergamenky 12 Prague Czech Republic Charles Univ Prague CAPI Fac Med 1 Salmovska 3 Prague Czech Republic

The imaging method of SPECT (Single Photon Emission Computed Tomography) is used in nuclear medicine for diagnostics of various diseases or organs malfunctions. The distribution of medically injected, inhaled, or ingested radionuclides (radiotracers) in the patient body is imaged using gamma-ray sensitive camera with suitable imaging collimator. The 3D image is then calculated by combining many images taken from different observation angles. Most of SPECT systems use scintillator based cameras. These cameras do not provide good energy resolution and do not allow efficient suppression of unwanted signals such as those caused by Compton scattering. The main goal of this work is evaluation of Timepix3 detector properties for SPECT method for functional imaging of small animals during preclinical studies. Advantageous Timepix3 properties such as energy and spatial resolution are exploited for significant image quality improvement. Preliminary measurements were performed on specially prepared plastic phantom with cavities filled by radioisotopes and then repeated with in vivo mouse sample.

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

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Noise-reduction approaches to single-shot dual-energy imaging with a multilayer detector

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JOURNAL OF INSTRUMENTATION 2019年第1期14卷

作者： Kim, D. W. Park, J. Kim, J. Kim, H. K. Pusan Natl Univ Sch Mech Engn Busandaehak Ro 63Beon Gil Busan 46241 South Korea Pusan Natl Univ Ctr Adv Med Engn Busandaehak Ro 63Beon Gil Busan 46241 South Korea

The single-shot dual-energy (DE) method using a sandwich-like multilayer detector generally suffers from noise in the resultant DE images due to the poor quantum noise in images obtained from the rear detector layer and its amplification due to the subtraction operation in DE reconstruction. The use of interlayer metal filter can further increase noise in DE images by increasing the rear-detector quantum noise. We have adopted several noise-reduction algorithms to the single-shot DE reconstruction, which included the Gaussian-filtering noise reduction (GNR), the median-filtering noise reduction (MNR), and the anti-correlated noise reduction (ANR). We assessed the effectiveness of noise-reduction methods by investigating noise and dose-normalized contrast-to-noise ratio for a mouse-mimicking phantom consisting of aluminum bone and polyurethane soft tissues. Noise-power spectrum was also measured to investigate correlation noise. Overall, the ANR showed the best performance. At some extreme imaging technique conditions, such as a lower tube voltages and a larger spectral energy separation using thick copper sheets between the front and rear detector layers, the MNR outperformed the ANR. The performance of GNR was nearly similar to that of MNR. The results were well reflected into demonstration bone images obtained for a postmortem mouse. Although the ANR was effective to reduce noise in the single-shot DE imaging using the sandwich detector, multivariate optimization of ANR parameters with respect to imaging tasks and imaging techniques is remained as a future study.

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

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Mixture model based joint-MAP reconstruction of attenuation and activity maps in TOF-PET

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JOURNAL OF INSTRUMENTATION 2018年第6期13卷 P06005-P06005页

作者： Hemmati, H. Kamali-Asl, A. Ghafarian, P. Ay, M. R. Shahid Beheshti Univ Dept Med Radiat Engn Tehran Iran Shahid Beheshti Univ Med Sci NRITLD Chron Resp Dis Res Ctr Tehran Iran Shahid Beheshti Univ Med Sci Masih Daneshvari Hosp PET CT Tehran Iran Shahid Beheshti Univ Med Sci Masih Daneshvari Hosp Cyclotron Ctr Tehran Iran Univ Tehran Med Sci Res Ctr Mol & Cellular Imaging Tehran Iran

A challenge to have quantitative positron emission tomography (PET) images is to provide an accurate and patient-specific photon attenuation correction. In PET/MR scanners, the nature of MR signals and hardware limitations have led to a real challenge on the attenuation map extraction. Except for a constant factor, the activity and attenuation maps from emission data on TOF-PET system can be determined by the maximum likelihood reconstruction of attenuation and activity approach (MLAA) from emission data. The aim of the present study is to constrain the joint estimations of activity and attenuation approach for PET system using a mixture model prior based on the attenuation map histogram. This novel prior enforces non-negativity and its hyperparameters can be estimated using a mixture decomposition step from the current estimation of the attenuation map. The proposed method can also be helpful on the solving of scaling problem and is capable to assign the predefined regional attenuation coefficients with some degree of confidence to the attenuation map similar to segmentation-based attenuation correction approaches. The performance of the algorithm is studied with numerical and Monte Carlo simulations and a phantom experiment and was compared with MLAA algorithm with and without the smoothing prior. The results demonstrate that the proposed algorithm is capable of producing the cross-talk free activity and attenuation images from emission data. The proposed approach has potential to be a practical and competitive method for joint reconstruction of activity and attenuation maps from emission data on PET/MR and can be integrated on the other methods.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided diagnosis Attenuation map Maximum a Posteriori

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Assessment of the effects of different sample perfusion procedures on phase-contrast tomographic images of mouse spinal cord

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JOURNAL OF INSTRUMENTATION 2018年第3期13卷 C03027-C03027页

作者： Stefanutti, E. Sierra, A. Miocchi, P. Massimi, L. Brun, F. Maugeri, L. Bukreeva, I. Nurmi, A. Provinciali, G. Begani Tromba, G. Grohn, O. Giove, F. Cedola, A. Fratini, M. IRCCS Fdn Santa Lucia Via Ardeatina 306-354 I-00142 Rome Italy Univ Eastern Finland Biomed Imaging Unit AI Virtanen Inst Mol Sci Neulaniementie 2 FIN-70211 Kuopio Finland Sapienza Univ CNR Inst Nanotechnol Phys Dept Piazzale Aldo Moro 2 I-00185 Rome Italy Charles River Discovery Serv Microkatu 1 Kuopio 70210 Finland Sapienza Univ Phys Dept Piazzale Aldo Moro 2 I-00185 Rome Italy Elettra Synchrotron Radiat Trieste SCpA Area Sci Pk I-34149 Trieste Italy Museo Stor Fis Ctr Fermi Piazza Viminale 1 I-00184 Rome Italy Ctr Studi & Ric Enrico Fermi Piazza Viminale 1 I-00184 Rome Italy

Synchrotron X-ray Phase Contrast micro-Tomography (SXrPC mu T) is a powerful tool in the investigation of biological tissues, including the central nervous system (CNS), and it allows to simultaneously detect the vascular and neuronal network avoiding contrast agents or destructive sample preparations. However, specific sample preparation procedures aimed to optimize the achievable contrast-and signal-to-noise ratio (CNR and SNR, respectively) are required. Here we report and discuss the effects of perfusion with two different fixative agents (ethanol and paraformaldehyde) and with a widely used contrast medium (MICROFIL (R)) on mouse spinal cord. As a main result, we found that ethanol enhances contrast at the grey/white matter interface and increases the contrast in correspondence of vascular features and fibres, thus providing an adequate spatial resolution to visualise the vascular network at the microscale. On the other hand, ethanol is known to induce tissue dehydration, likely reducing cell dimensions below the spatial resolution limit imposed by the experimental technique. Nonetheless, neurons remain well visible using either perfused paraformaldehyde or MICROFIL (R) compound, as these latter media do not affect tissues with dehydration effects. Paraformaldehyde appears as the best compromise: it is not a contrast agent, like MICROFIL (R), but it is less invasive than ethanol and permits to visualise well both cells and blood vessels. However, a quantitative estimation of the relative grey matter volume of each sample has led us to conclude that no significant alterations in the grey matter extension compared to the white matter occur as a consequence of the perfusion procedures tested in this study.

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

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3D map of theranostic nanoparticles distribution in mice brain and liver by means of X-ray Phase Contrast Tomography

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JOURNAL OF INSTRUMENTATION 2018年第1期13卷 C01049-C01049页

作者： Longo, E. Bravin, A. Brun, F. Bukreeva, I. Cedola, A. Fratini, M. Le Guevel, X. Massimi, L. Sancey, L. Tillement, O. Zeitoun, P. de la Rochefoucauld, O. Univ Paris Saclay Ecole Polytech Lab Opt Appl UMR7639 ENSTACNRS 181 Chemin Huniere & Joncherettes F-91762 Palaiseau France European Synchrotron Radiat Facil 71 Ave Martyrs F-38043 Grenoble France CNR Inst Nanotechnol Rome Unit Piazzale Aldo Moro 5 I-00185 Rome Italy Santa Lucia Fdn MARBLab Via Ardeatina 306-354 I-00142 Rome Italy Inst Adv Biosci U1209 UMR5309 UGA Allee Alpes Site Sante F-38700 Grenoble France Univ Claude Bernard Lyon1 CNRS UMR5306 Inst Lumiere Mat F-69622 Villeurbanne France Imagine Opt Rue Francois Mitterrand F-33400 Talence France

The word "theranostic" derives from the fusion of two terms: therapeutic and diagnostic. It is a promising research field that aims to develop innovative therapies with high target specificity by exploiting the therapeutic and diagnostic properties, in particular for metal-based nanoparticles (NPs) developed to erase cancer. In the framework of a combined research program on low dose X-ray imaging and theranostic nanoparticles (NPs), high resolution Phase-Contrast Tomography images of mice organs injected with gadolinium and gold-NPs were acquired at the European Synchrotron Radiation Facility (ESRF). Both compounds are good X-ray contrast agents due to their high attenuation coefficient with respect to biological tissues, especially immediately above K-edge energy. X-ray tomography is a powerful non-invasive technique to image the 3D vasculature network in order to detect abnormalities. Phase contrast methods provide more detailed anatomical information with higher discrimination among soft tissues. We present the images of mice liver and brain injected with gold and gadolinium NPs, respectively. We discuss different image processing methods used aiming at enhancing the accuracy on localizing nanoparticles.

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

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Evaluation of Timepix3 based CdTe photon counting detector for fully spectroscopic small animal SPECT imaging

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JOURNAL OF INSTRUMENTATION 2018年第1期13卷 C01001-C01001页

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

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Semi-analytic off-axis X-ray source model

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JOURNAL OF INSTRUMENTATION 2017年第10期12卷

作者： Shamshad, M. Anjomrouz, M. Smithies, D. J. Largeau, A. Lu, G. Atharifard, A. Broeke, L. Vanden Aamir, R. Panta, R. K. Walsh, M. F. Goulter, B. P. Healy, J. L. Bheesette, S. Bell, S. T. Bateman, C. J. Butler, A. P. H. Butler, P. H. Univ Otago Dept Radiol 2 Riccarton Ave Christchurch 8140 New Zealand Univ Canterbury Dept Biol Private Bag 4800 Christchurch 8140 New Zealand MARS Bioimaging Ltd 29a Clyde Rd Christchurch New Zealand Univ Canterbury Dept Phys & Astron Private Bag 4800 Christchurch 8140 New Zealand European Org Nucl Res CERN Geneva Switzerland Univ Strasbourg Telecom Phys Strasbourg 300 Bd Sebastien Brant Strasbourg France

Spectral computed tomography (CT) systems are employed with energy-resolving photon counting detectors. Incorporation of a spectrally accurate x-ray beam model in image reconstruction helps to improve material identification and quantification by these systems. Using an inaccurate x-ray model in spectral reconstruction can lead to severe image artifacts, one of the extreme cases of this is the well-known beam-hardening artifacts. An often overlooked spectral feature of x-ray beams in spectral reconstruction models is the angular dependence of the spectrum with reference to the central beam axis. To address these factors, we have developed a parameterized semi-analytical x-ray source model in the diagnostic imaging range (30-120 kVp) by applying regression techniques to data obtained from Monte Carlo simulations (EGSnrc). This x-ray beam model is generalized to describe the off-axis spectral information within +/- 17 degrees along theta (vertical direction), +/- 5 degrees along phi (horizontal direction) of the central axis, and can be parameterized for specific x-ray tube models. Comparisons of our model with those generated by SpekCalc, TOPAS, and IPEM78 at central axis show good agreement (within 2%). We have evaluated the model with experimental data collected with a small animal spectral scanner.

关键词： medical-image reconstruction methods and algorithms, computer-aided diagnosis Models and simulations Radiation calculations X-ray generators and sources

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Cerenkov luminescence imaging guided selective-reconstruction for a flexible dual-head PET

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JOURNAL OF INSTRUMENTATION 2017年第4期12卷 P04005-P04005页

作者： Yang, D. Chen, X. Zhang, C. Wan, L. Meng, F. Xie, Q. Liang, J. Xidian Univ Engn Res Ctr Mol 266 Xinglong Sect Xifeng Rd Xian 710071 Shaanxi Peoples R China Xidian Univ Neuro Imaging Minist Educ 266 Xinglong Sect Xifeng Rd Xian 710071 Shaanxi Peoples R China Xidian Univ Sch Life Sci & Technol 266 Xinglong Sect Xifeng Rd Xian 710071 Shaanxi Peoples R China Hangzhou Dianzi Univ Inst Informat & Control Xiasha Higher Educ Zone Hangzhou 310018 Zhejiang Peoples R China Huazhong Univ Sci & Technol Sch Life Sci & Technol 1037 Luoyu Rd Wuhan 430074 Hubei Peoples R China

Dual-head PET can simply and flexibilly adjust its architecture to fit the size of the imaging object, making it great potential for simultaneous multi-modality molecular imaging. In this paper, we proposed conceptally dual-modality imaging system of distance-adjustable dual-head PET and Cerenkov luminescence imaging (CLI), and implemented a CLI guided selectivere-construction method. In the selective-reconstruction, we reconstructed the information inside a predefined region of interest using a fine voxel, whereas reconstructed other regions using a coarse voxel. We used CLI data as a priori information to outline the predefined region of interest. Simultaneously, for reducing the computaion burden, an attenuation map with a coarse voxel size was used for the attenuation correction. We demonstrated the feasibility and effectiveness of our proposed method with Monte Carlo based simulations by reconstructing phantom consisted of two hot rods. Experiment results show that an most improved efficiency over 70 times speedup with an MSE of 5.2235.

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

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A crystal identification method for monolithic phoswich detectors based on scintillation light distribution

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JOURNAL OF INSTRUMENTATION 2016年第12期11卷 12009-12009页

作者： Preziosi, E. Pani, R. Trigila, C. Polito, C. Bettiol, M. Borrazzo, C. Cinti, M. N. Fabbri, A. Pellegrini, R. Pani, R. Sapienza Univ Rome Sch Biol & Mol Med Morphofunct Sci Biophys SAIMLAL Dept Rome Italy Sapienza Univ Rome Dept Phys Rome Italy Sapienza Univ Rome SAIMLAL Dept Morphogenesis & Tissue Engn Rome Italy Campus Biomed Univ Dept Radiotherapy Rome Italy Sapienza Univ Rome Dept Mol Med Rome Italy Sapienza Univ Rome Postgrad Sch Med Phys Rome Italy Sapienza Univ Rome Dept Medicosurg Sci & Biotechnol Rome Italy

Phoswich detectors based on scintillation crystals are widely diffused for both PET and SPECT applications. In order to separate the signals arising from different layers many methods have been proposed in literature. Separation of the layers commonly relies on time discrimination or pulse height discrimination. In this work, by means of experimental measurement on a phoswich detector based on Lanthanum Bromide and Lutetium Fine Silicate monolithic crystals, a novel method allowing to separate signals coming from different layers has been evaluated. The main feature of this method, specifically developed for phoswich based on monolithic scintillation crystals, is the discrimination capability based on the scintillation light distribution shape. For this reason, the findings that will be shown could be easily extended to whatever combination of scintillator, independently from their decay time or light yield.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) Gamma detectors (scintillators, CZT, HPG, HgI etc) medical-image reconstruction methods and algorithms, computer-aided diagnosis

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Analytic signal extraction approach based on 2D Grating Interferometer and systematic comparison between 2D GI and 1D case

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JOURNAL OF INSTRUMENTATION 2016年第3期11卷 C03031-C03031页

作者： Ju, Z. Wang, Y. Li, P. Zhu, Z. Zhang, K. Huang, W. Yuan, Q. Wu, Z. Zhu, P. Chinese Acad Sci Inst High Energy Phys Yuquan Rd Beijing Peoples R China Univ Sci & Technol China Natl Synchrotron Radiat Lab Hefei 230026 Peoples R China

X-ray imaging method based on 2D grating interferometer was proposed and studied recently, to overcome the limitations in signal extraction and phase retrieval when using 1D grating interferometer. In this paper, the concept of angle-signal response function is proposed, and different surfaces of different 2D setups under the condition of parallel coherent light are calculated and depicted with Matlab. Based on this concept, performance of 2D grating interferometer is systematically analyzed and an analytic 2D signal extraction approach is theoretically proposed. Besides, signal extraction, phase retrieval and feasibility of using conventional source are also briefly discussed and compared between 2D grating interferometer and 1D case.

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

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