Refraction-compensated motion tracking of unrestrained small animals in positron emission tomography.

Science.gov (United States)

Kyme, Andre; Meikle, Steven; Baldock, Clive; Fulton, Roger

2012-08-01

Motion-compensated radiotracer imaging of fully conscious rodents represents an important paradigm shift for preclinical investigations. In such studies, if motion tracking is performed through a transparent enclosure containing the awake animal, light refraction at the interface will introduce errors in stereo pose estimation. We have performed a thorough investigation of how this impacts the accuracy of pose estimates and the resulting motion correction, and developed an efficient method to predict and correct for refraction-based error. The refraction model underlying this study was validated using a state-of-the-art motion tracking system. Refraction-based error was shown to be dependent on tracking marker size, working distance, and interface thickness and tilt. Correcting for refraction error improved the spatial resolution and quantitative accuracy of motion-corrected positron emission tomography images. Since the methods are general, they may also be useful in other contexts where data are corrupted by refraction effects. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Technology challenges in small animal PET imaging

International Nuclear Information System (INIS)

Lecomte, Roger

2004-01-01

Positron Emission Tomography (PET) is a non-invasive nuclear imaging modality allowing biochemical processes to be investigated in vivo with sensitivity in the picomolar range. For this reason, PET has the potential to play a major role in the emerging field of molecular imaging by enabling the study of molecular pathways and genetic processes in living animals non-invasively. The challenge is to obtain a spatial resolution that is appropriate for rat and mouse imaging, the preferred animal models for research in biology, while achieving a sensitivity adequate for real-time measurement of rapid dynamic processes in vivo without violating tracer kinetic principles. An overview of the current state of development of dedicated small animal PET scanners is given, and selected applications are reported and discussed with respect to performance and significance to research in biology

Automated analysis of small animal PET studies through deformable registration to an atlas

NARCIS (Netherlands)

Gutierrez, Daniel F.; Zaidi, Habib

This work aims to develop a methodology for automated atlas-guided analysis of small animal positron emission tomography (PET) data through deformable registration to an anatomical mouse model. A non-rigid registration technique is used to put into correspondence relevant anatomical regions of

Experimental results and first 22Na source image reconstruction by two prototype modules in coincidence of a liquid xenon positron emission tomograph for small animal imaging

International Nuclear Information System (INIS)

Gallin-Martel, M.-L.; Grondin, Y.; Gac, N.; Carcagno, Y.; Gallin-Martel, L.; Grondin, D.; Marton, M.; Muraz, J.-F; Rossetto, O.; Vezzu, F.

2012-01-01

A detector with a very specific design using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Two prototype modules equipped with Position Sensitive Photo Multiplier Tubes (PSPMTs) operating in the VUV range (178 nm) and at 165 K were built and studied in coincidence. This paper reports on energy, time and spatial resolution capabilities of this experimental test bench. Furthermore, these experimental results were used to perform the first image reconstruction of a 22 Na source placed in the experimental setup.

Non-Invasive in vivo Imaging in Small Animal Research

Directory of Open Access Journals (Sweden)

V. Koo

2006-01-01

Full Text Available Non-invasive real time in vivo molecular imaging in small animal models has become the essential bridge between in vitro data and their translation into clinical applications. The tremendous development and technological progress, such as tumour modelling, monitoring of tumour growth and detection of metastasis, has facilitated translational drug development. This has added to our knowledge on carcinogenesis. The modalities that are commonly used include Magnetic Resonance Imaging (MRI, Computed Tomography (CT, Positron Emission Tomography (PET, bioluminescence imaging, fluorescence imaging and multi-modality imaging systems. The ability to obtain multiple images longitudinally provides reliable information whilst reducing animal numbers. As yet there is no one modality that is ideal for all experimental studies. This review outlines the instrumentation available together with corresponding applications reported in the literature with particular emphasis on cancer research. Advantages and limitations to current imaging technology are discussed and the issues concerning small animal care during imaging are highlighted.

Experimental results and first {sup 22}Na source image reconstruction by two prototype modules in coincidence of a liquid xenon positron emission tomograph for small animal imaging

Energy Technology Data Exchange (ETDEWEB)

Gallin-Martel, M.-L., E-mail: mlgallin@lpsc.in2p3.fr [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 avenue des Martyrs 38026 Grenoble Cedex (France); Grondin, Y. [Laboratoire TIMC/IMAG, CNRS et Universite Joseph Fourier, Pavillon Taillefer 38706 La Tronche Cedex (France); Gac, N. [Laboratoire L2S, UMR 8506 CNRS - SUPELEC - Univ Paris-Sud, Gif sur Yvette F-91192 (France); Carcagno, Y.; Gallin-Martel, L.; Grondin, D.; Marton, M.; Muraz, J.-F; Rossetto, O.; Vezzu, F. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 avenue des Martyrs 38026 Grenoble Cedex (France)

2012-08-01

A detector with a very specific design using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Two prototype modules equipped with Position Sensitive Photo Multiplier Tubes (PSPMTs) operating in the VUV range (178 nm) and at 165 K were built and studied in coincidence. This paper reports on energy, time and spatial resolution capabilities of this experimental test bench. Furthermore, these experimental results were used to perform the first image reconstruction of a {sup 22}Na source placed in the experimental setup.

Techniques necessary for multiple tracer quantitative small-animal imaging studies

International Nuclear Information System (INIS)

Sharp, Terry L.; Dence, Carmen S.; Engelbach, John A.; Herrero, Pilar; Gropler, Robert J.; Welch, Michael J.

2005-01-01

Introduction: An increasing number and variety of studies on rodent models are being conducted using small-animal positron emission tomography scanners. We aimed to determine if animal handling techniques could be developed to perform routine animal imaging in a timely and efficient manner and with minimal effect on animal physiology. These techniques need to be reproducible in the same animal while maintaining hemodynamic and physiological stability. Methods: The necessary techniques include (a) the use of inhalant anesthesia, (b) arterial and venous cannulation for multiple tracer administrations and blood sampling, (c) development of small-volume analytic columns and techniques and (d) measurement of the physiological environment during the imaging session. Results: We provide an example of a cardiac imaging study using four radiotracers ( 15 O-water, 1-[ 11 C]-acetate, 1-[ 11 C]-palmitate and 1-[ 11 C]-glucose) injected into normal rats. Plasma substrates, CO 2 production and total metabolites were measured. The animals remained anesthetized over the entire imaging session, and their physiological state was maintained. Conclusion: The intrastudy stability of the physiological measurements and substrate levels and interstudy reproducibility of the measurements are reported

Open-Source Medical Devices (OSMD) Design of a Small Animal Radiotherapy System

Science.gov (United States)

Prajapati, S.; Mackie, T. R.; Jeraj, R.

2014-03-01

Open-Source Medical Devices (OSMD) was initiated with the goal of facilitating medical research by developing medical technologies including both hardware and software on an open-source platform. Our first project was to develop an integrated imaging and radiotherapy device for small animals that includes computed tomography (CT), positron emission tomography (PET) and radiation therapy (RT) modalities for which technical specifications were defined in the first OSMD conference held in Madison, Wisconsin, USA in December 2011. This paper specifically focuses on the development of a small animal RT (micro-RT) system by designing a binary micro multileaf collimator (bmMLC) and a small animal treatment planning system (SATPS) to enable intensity modulated RT (IMRT). Both hardware and software projects are currently under development and their current progresses are described. After the development, both bmMLC and TPS will be validated and commissioned for a micro-RT system. Both hardware design and software development will be open-sourced after completion.

Design of an advanced positron emission tomography detector system and algorithms for imaging small animal models of human disease

Science.gov (United States)

Foudray, Angela Marie Klohs

Detecting, quantifying and visualizing biochemical mechanism in a living system without perturbing function is the goal of the instrument and algorithms designed in this thesis. Biochemical mechanisms of cells have long been known to be dependent on the signals they receive from their environment. Studying biological processes of cells in-vitro can vastly distort their function, since you are removing them from their natural chemical signaling environment. Mice have become the biological system of choice for various areas of biomedical research due to their genetic and physiological similarities with humans, the relatively low cost of their care, and their quick breeding cycle. Drug development and efficacy assessment along with disease detection, management, and mechanism research all have benefited from the use of small animal models of human disease. A high resolution, high sensitivity, three-dimensional (3D) positioning positron emission tomography (PET) detector system was designed through device characterization and Monte Carlo simulation. Position-sensitive avalanche photodiodes (PSAPDs) were characterized in various packaging configurations; coupled to various configurations of lutetium oxyorthosilicate (LSO) scintillation crystals. Forty novelly packaged final design devices were constructed and characterized, each providing characteristics superior to commercially available scintillation detectors used in small animal imaging systems: ˜1mm crystal identification, 14-15% of 511 keV energy resolution, and averaging 1.9 to 5.6 ns coincidence time resolution. A closed-cornered box-shaped detector configuration was found to provide optimal photon sensitivity (˜10.5% in the central plane) using dual LSO-PSAPD scintillation detector modules and Monte Carlo simulation. Standard figures of merit were used to determine optimal system acquisition parameters. A realistic model for constituent devices was developed for understanding the signals reported by the

New detector developments for high resolution positron emission tomography

International Nuclear Information System (INIS)

Ziegler, S.I.; Pichler, B.; Lorenz, E.

1998-01-01

The strength of quantitative, functional imaging using positron emission tomography, specially in small animals, is limited due to the spatial resolution. Therefore, various tomograph designs employing new scintillators, light sensors, or coincidence electronic are investigated to improve resolution without losses in sensitivity. Luminous scintillators with short light decay time in combination with novel readout schemes using photomultipliers or semiconductor detectors are currently tested by several groups and are implemented in tomographs for small animals. This review summarises the state of development in high resolution positron emission tomography with a detailed description of a system incorporating avalanche photodiode arrays and small scintillation crystals. (orig.) [de

Positron-attachment to small molecules: Vibrational enhancement of positron affinities with configuration interaction level of multi-component molecular orbital approach

Energy Technology Data Exchange (ETDEWEB)

Tachikawa, Masanori [Quantum Chemistry Division, Graduate School of NanoBioScience, Yokohama City University, 22-2 Seto, Kanazawa, Yokohama 236-0027 (Japan)

2015-12-31

To theoretically demonstrate the binding of a positron to small polarized molecules, we have calculated the vibrational averaged positron affinity (PA) values along the local vibrational contribution with the configuration interaction level of multi-component molecular orbital method. This method can take the electron-positron correlation contribution into account through single electronic - single positronic excitation configurations. The PA values are enhanced by including the local vibrational contribution from vertical PA values due to the anharmonicity of the potential.

Development of a SiPM-based PET imaging system for small animals

International Nuclear Information System (INIS)

Lu, Yanye; Yang, Kun; Zhou, Kedi; Zhang, Qiushi; Pang, Bo; Ren, Qiushi

2014-01-01

Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development

Development of a SiPM-based PET imaging system for small animals

Energy Technology Data Exchange (ETDEWEB)

Lu, Yanye [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Yang, Kun, E-mail: yangkun9999@hotmail.com [Department of Control Technology and Instrumentation, College of Quality and Technical Supervision, Hebei University, Baoding, 071000 (China); Zhou, Kedi; Zhang, Qiushi; Pang, Bo [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Ren, Qiushi, E-mail: renqsh@coe.pku.edu.cn [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

2014-04-11

Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development.

Evaluation of the P-glycoprotein- and breast cancer resistance protein-mediated brain penetration of 11C-labeled topotecan using small-animal positron emission tomography

International Nuclear Information System (INIS)

Yamasaki, Tomoteru; Fujinaga, Masayuki; Kawamura, Kazunori; Hatori, Akiko; Yui, Joji; Nengaki, Nobuki; Ogawa, Masanao; Yoshida, Yuichiro; Wakizaka, Hidekatsu; Yanamoto, Kazuhiko; Fukumura, Toshimitsu; Zhang Mingrong

2011-01-01

Introduction: Topotecan (TPT) is a camptothecin derivative and is an anticancer drug working as a topoisomerase-I-specific inhibitor. But TPT cannot penetrate through the blood-brain barrier. In this study, we synthesized a new positron emission tomography (PET) probe, [ 11 C]TPT, to evaluate the P-glycoprotein (Pgp)- and breast cancer resistance protein (BCRP)-mediated brain penetration of [ 11 C]TPT using small-animal PET. Methods: [ 11 C]TPT was synthesized by the reaction of a desmethyl precursor with [ 11 C]CH 3 I. In vitro study using [ 11 C]TPT was carried out in MES-SA and doxorubicin-resistant MES-SA/Dx5 cells in the presence or absence of elacridar, a specific inhibitor for Pgp and BCRP. The biodistribution of [ 11 C]TPT was determined using small-animal PET and the dissection method in mice. Results: The transport of [ 11 C]TPT to the extracellular side was determined in MES-SA/Dx5 cells exhibiting the expressions of Pgp and BCRP at high levels. This transport was inhibited by coincubation with elacridar. In Mdr1a/b -/- Bcrp1 -/- mice, PET results indicated that the brain uptake of [ 11 C]TPT was about two times higher than that in wild-type mice. Similarly, the brain penetration of [ 11 C]TPT in wild-type mice was increased by treatment with elacridar. The radioactivity in the brain of elacridar-treated mice was maintained at a certain level after the injection of [ 11 C]TPT, although the radioactivity in the blood decreased with time. Conclusions: We demonstrated the increase of brain penetration of [ 11 C]TPT by deficiency and inhibition of Pgp and BCRP functions using small-animal PET in mice.

Simulation of time curves in small animal PET using GATE

International Nuclear Information System (INIS)

Simon, Luc; Strul, Daniel; Santin, Giovanni; Krieguer, Magalie; Morel, Christian

2004-01-01

The ClearPET project of the Crystal Clear Collaboration (CCC) is building spin-off technology for high resolution small animal Positron Emission Tomography (PET). Monte Carlo simulation is essential for optimizing the specifications of these systems with regards to their most important characteristics, such as spatial resolution, sensitivity, or count rate performance. GATE, the Geant4 Application for Tomographic Emission simulates the passing of time during real acquisitions, allowing to handle dynamic systems such as decaying source distributions or moving detectors. GATE output is analyzed on an event-by-event basis. The time associated with each single event allows to sort coincidences and to model dead-time. This leads to the study of time curves for a prospective small animal PET scanner design. The count rates of true, and random coincidences are discussed together with the corresponding Noise Equivalent Count (NEC) rates as a function of some PET scanner specifications such as detector dead time, or coincidence time window

Multi-modality image reconstruction for dual-head small-animal PET

International Nuclear Information System (INIS)

Huang, Chang-Han; Chou, Cheng-Ying

2015-01-01

The hybrid positron emission tomography/computed tomography (PET/CT) or positron emission tomography/magnetic resonance imaging (PET/MRI) has become routine practice in clinics. The applications of multi-modality imaging can also benefit research advances. Consequently, dedicated small-imaging system like dual-head small-animal PET (DHAPET) that possesses the advantages of high detection sensitivity and high resolution can exploit the structural information from CT or MRI. It should be noted that the special detector arrangement in DHAPET leads to severe data truncation, thereby degrading the image quality. We proposed to take advantage of anatomical priors and total variation (TV) minimization methods to reconstruct PET activity distribution form incomplete measurement data. The objective is to solve the penalized least-squares function consisted of data fidelity term, TV norm and medium root priors. In this work, we employed the splitting-based fast iterative shrinkage/thresholding algorithm to split smooth and non-smooth functions in the convex optimization problems. Our simulations studies validated that the images reconstructed by use of the proposed method can outperform those obtained by use of conventional expectation maximization algorithms or that without considering the anatomical prior information. Additionally, the convergence rate is also accelerated.

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Eiji [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)]. E-mail: rush@nirs.go.jp; Kitamura, Keishi [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Kimura, Yuichi [Tokyo Metropolitan Institute of Gerontology, Nakamachi 1-1 Itabashi-ku, Tokyo 173-0022 (Japan); Nishikido, Fumihiko [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Shibuya, Kengo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Yamaya, Taiga [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Murayama, Hideo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)

2007-02-01

In a conventional positron emission tomography (PET) detector, detected events are projected onto a 2D position histogram by an Anger calculation for crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in the entire detector. Peaks which are projected for each crystal in the histogram are blurred, and this causes ICS mispositioning. A depth-of-interaction (DOI) detector has been developed for the small animal PET scanner jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) which was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm{sup 3}. The FP-PMT has a large detective area (49x49 mm{sup 2}) and a small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident {gamma} rays in the crystals including ICS event. We, therefore, propose a novel method for ICS estimation using a statistical pattern recognition algorithm based on a support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using a Monte Carlo calculation. The success rate for ICS event identification is about 78% for non-training data. The SVM can achieve a true subtraction of ICS events from measured events, and it is also useful for random correction in PET.

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal positron emission tomography

International Nuclear Information System (INIS)

Yoshida, Eiji; Kitamura, Keishi; Kimura, Yuichi; Nishikido, Fumihiko; Shibuya, Kengo; Yamaya, Taiga; Murayama, Hideo

2007-01-01

In a conventional positron emission tomography (PET) detector, detected events are projected onto a 2D position histogram by an Anger calculation for crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in the entire detector. Peaks which are projected for each crystal in the histogram are blurred, and this causes ICS mispositioning. A depth-of-interaction (DOI) detector has been developed for the small animal PET scanner jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) which was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm 3 . The FP-PMT has a large detective area (49x49 mm 2 ) and a small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident γ rays in the crystals including ICS event. We, therefore, propose a novel method for ICS estimation using a statistical pattern recognition algorithm based on a support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using a Monte Carlo calculation. The success rate for ICS event identification is about 78% for non-training data. The SVM can achieve a true subtraction of ICS events from measured events, and it is also useful for random correction in PET

Evaluation of the P-glycoprotein- and breast cancer resistance protein-mediated brain penetration of {sup 11}C-labeled topotecan using small-animal positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Yamasaki, Tomoteru; Fujinaga, Masayuki; Kawamura, Kazunori; Hatori, Akiko; Yui, Joji [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Nengaki, Nobuki; Ogawa, Masanao; Yoshida, Yuichiro [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); SHI Accelerator Service, Ltd., Tokyo 141-8686 (Japan); Wakizaka, Hidekatsu [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Yanamoto, Kazuhiko [Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka 565-0871 (Japan); Fukumura, Toshimitsu [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Zhang Mingrong, E-mail: zhang@nirs.go.jp [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

2011-07-15

Introduction: Topotecan (TPT) is a camptothecin derivative and is an anticancer drug working as a topoisomerase-I-specific inhibitor. But TPT cannot penetrate through the blood-brain barrier. In this study, we synthesized a new positron emission tomography (PET) probe, [{sup 11}C]TPT, to evaluate the P-glycoprotein (Pgp)- and breast cancer resistance protein (BCRP)-mediated brain penetration of [{sup 11}C]TPT using small-animal PET. Methods: [{sup 11}C]TPT was synthesized by the reaction of a desmethyl precursor with [{sup 11}C]CH{sub 3}I. In vitro study using [{sup 11}C]TPT was carried out in MES-SA and doxorubicin-resistant MES-SA/Dx5 cells in the presence or absence of elacridar, a specific inhibitor for Pgp and BCRP. The biodistribution of [{sup 11}C]TPT was determined using small-animal PET and the dissection method in mice. Results: The transport of [{sup 11}C]TPT to the extracellular side was determined in MES-SA/Dx5 cells exhibiting the expressions of Pgp and BCRP at high levels. This transport was inhibited by coincubation with elacridar. In Mdr1a/b{sup -/-}Bcrp1{sup -/-} mice, PET results indicated that the brain uptake of [{sup 11}C]TPT was about two times higher than that in wild-type mice. Similarly, the brain penetration of [{sup 11}C]TPT in wild-type mice was increased by treatment with elacridar. The radioactivity in the brain of elacridar-treated mice was maintained at a certain level after the injection of [{sup 11}C]TPT, although the radioactivity in the blood decreased with time. Conclusions: We demonstrated the increase of brain penetration of [{sup 11}C]TPT by deficiency and inhibition of Pgp and BCRP functions using small-animal PET in mice.

The motivations and methodology for high-throughput PET imaging of small animals in cancer research

Energy Technology Data Exchange (ETDEWEB)

Aide, Nicolas [Francois Baclesse Cancer Centre, Nuclear Medicine Department, Caen Cedex (France); Caen University, BioTICLA team, EA 4656, IFR 146, Caen (France); Visser, Eric P. [Radboud University Nijmegen Medical Center, Nuclear Medicine Department, Nijmegen (Netherlands); Lheureux, Stephanie [Caen University, BioTICLA team, EA 4656, IFR 146, Caen (France); Francois Baclesse Cancer Centre, Clinical Research Unit, Caen (France); Heutte, Natacha [Francois Baclesse Cancer Centre, Clinical Research Unit, Caen (France); Szanda, Istvan [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Hicks, Rodney J. [Peter MacCallum Cancer Centre, Centre for Molecular Imaging, East Melbourne (Australia)

2012-09-15

Over the last decade, small-animal PET imaging has become a vital platform technology in cancer research. With the development of molecularly targeted therapies and drug combinations requiring evaluation of different schedules, the number of animals to be imaged within a PET experiment has increased. This paper describes experimental design requirements to reach statistical significance, based on the expected change in tracer uptake in treated animals as compared to the control group, the number of groups that will be imaged, and the expected intra-animal variability for a given tracer. We also review how high-throughput studies can be performed in dedicated small-animal PET, high-resolution clinical PET systems and planar positron imaging systems by imaging more than one animal simultaneously. Customized beds designed to image more than one animal in large-bore small-animal PET scanners are described. Physics issues related to the presence of several rodents within the field of view (i.e. deterioration of spatial resolution and sensitivity as the radial and the axial offsets increase, respectively, as well as a larger effect of attenuation and the number of scatter events), which can be assessed by using the NEMA NU 4 image quality phantom, are detailed. (orig.)

Application of position-sensitive detectors to positron imaging

International Nuclear Information System (INIS)

Yamashita, Takaji; Uchida, Hiroshi; Watanabe, Mitsuo; Omura, Tomohide

1994-01-01

Positron imaging including positron emission tomography (PET) is expected to be a promising tool for basic and clinical research, because it makes possible the study of regional chemistry within multiple organs of the body in living human beings and experimental animals. New schemes of high resolution block detectors have been developed to improve the performance of positron imaging systems, which employ small segments of bismuth germanate (BGO) arrays and position-sensitive photomultiplier tubes (PS-PMT). The coincidence detector resolution of less than 2.0 mm in full width at half maximum was achieved with the detectors, which is very close to the theoretical resolution limit in positron imaging. (author)

Development of a New Positron Emission Tomography Tracer for Targeting Tumor Angiogenesis: Synthesis, Small Animal Imaging, and Radiation Dosimetry

Directory of Open Access Journals (Sweden)

David S. Lalush

2013-05-01

Full Text Available Angiogenesis plays a key role in cancer progression and correlates with disease aggressiveness and poor clinical outcomes. Affinity ligands discovered by screening phage display random peptide libraries can be engineered to molecularly target tumor blood vessels for noninvasive imaging and early detection of tumor aggressiveness. In this study, we tested the ability of a phage-display-selected peptide sequence recognizing specifically bone marrow- derived pro-angiogenic tumor-homing cells, the QFP-peptide, radiolabeled with 64Cu radioisotope to selectively image tumor vasculature in vivo by positron emission tomography (PET. To prepare the targeted PET tracer we modified QFP-phage with the DOTA chelator and radiolabeled the purified QFP-phage-DOTA intermediate with 64Cu to obtain QFP-targeted radioconjugate with high radiopharmaceutical yield and specific activity. We evaluated the new PET tracer in vivo in a subcutaneous (s.c. Lewis lung carcinoma (LLC mouse model and conducted tissue distribution, small animal PET/CT imaging study, autoradiography, histology, fluorescence imaging, and dosimetry assessments. The results from this study show that, in the context of the s.c. LLC immunocompetent mouse model, the QFP-tracer can target tumor blood vessels selectively. However, further optimization of the biodistribution and dosimetry profile of the tracer is necessary to ensure efficient radiopharmaceutical applications enabled by the biological specificity of the QFP-peptide.

Positron emission tomography of incidentally detected small pulmonary nodules

DEFF Research Database (Denmark)

Fischer, B M; Mortensen, J; Dirksen, A

2004-01-01

The aim of this study was to assess the value of fluorodeoxyglucose positron emission tomography (FDG PET) imaging of small pulmonary nodules incidentally detected by spiral computed tomography (CT) in a high-risk population. Ten patients (five females, five males, aged 54-72 years) were recruited...

Programmable electronics for low-cost small animal PET/SPECT imaging

International Nuclear Information System (INIS)

Guerra, Pedro; Rubio, Jose L.; Kontaxakis, Georgios; Ortuno, Juan E.; Ledesma, Maria J.; Santos, Andres

2006-01-01

This work describes and characterizes the detector module of a novel positron/single photon emission (PET/SPECT) scanner for small animals. This detector consists of a YAP/LSO phoswich, a photomultiplier and acquisition front-end, and will be used as building block of a low-cost hybrid tomograph. The front-end processes data sampled at a fixed frequency, where a state-of-the-art programmable device estimates scintillation pulse parameters by means of digital algorithms. Finally, the estimated properties of the proposed detector module are used to model a rotating four-head scanner. The performance of the proposed PET/SPECT scanner is estimated and first results are promising in both modalities, deserving further research and optimization

Position-Sensitive Detector with Depth-of-Interaction Determination for Small Animal PET

CERN Document Server

Fedorov, A; Kholmetsky, A L; Korzhik, M V; Lecoq, P; Lobko, A S; Missevitch, O V; Tkatchev, A

2002-01-01

Crystal arrays made of LSO and LuAP crystals 2x2x10 mm pixels were manufactured for evaluation of detector with depth-of-interaction (DOI) determination capability intended for small animal positron emission tomograph. Position-sensitive LSO/LuAP phoswich DOI detector based on crystal 8x8 arrays and HAMAMATSU R5900-00-M64 position-sensitive multi-anode photomultiplier tube was developed and evaluated. Time resolution was found to be not worse than 1.0 ns FWHM for both layers, and spatial resolution mean value was 1.5 mm FWHM for the center of field-of-view.

SiliPET: Design of an ultra-high resolution small animal PET scanner based on stacks of semi-conductor detectors

International Nuclear Information System (INIS)

Cesca, N.; Auricchio, N.; Di Domenico, G.; Zavattini, G.; Malaguti, R.; Andritschke, R.; Kanbach, G.; Schopper, F.

2007-01-01

We studied with Monte Carlo simulations, using the EGSnrc code, a new scanner for small animal positron emission tomography (PET), based on stacks of double-sided semiconductor detectors. Each stack is composed of planar detectors with dimension 70x60x1 mm 3 and orthogonal strips on both sides with 500 μm pitch to read the two interaction coordinates, the third being the detector number in the stack. Multiple interactions in a stack are discarded. In this way, we achieve a precise determination of the first interaction point of the two 511 keV photons. The reduced dimensions of the scanner also improve the solid angle coverage resulting in a high sensitivity. Preliminary results of scanners based on Si planar detectors are presented and the initial tomographic reconstructions demonstrate very good spatial resolution limited only by the positron range. This suggests that, this is a promising new approach for small animal PET imaging. We are testing some double-sided silicon detectors, equipped with 128 orthogonal p and n strips on opposite sides using VATAGP3 ASIC by IDEAS

Advances in SPECT Instrumentation (Including Small Animal Scanners). Chapter 4

International Nuclear Information System (INIS)

Di Domenico, G.; Zavattini, G.

2009-01-01

Fundamental major efforts have been devoted to the development of positron emission tomography (PET) imaging modality over the last few decades. Recently, a novel surge of interest in single photon emission computed tomography (SPECT) technology has occurred, particularly after the introduction of the hybrid SPECT-CT imaging system. This has led to a flourishing of investigations in new types of detectors and collimators, and to more accurate refinement of reconstruction algorithms. Along with SPECT-CT, new, fast gamma cameras have been developed for dedicated cardiac imaging. The existing gap between PET and SPECT in sensitivity and spatial resolution is progressively decreasing, and this trend is particularly apparent in the field of small animal imaging where the most important advances have been reported in SPECT tomographs. An outline of the basic features of SPECT technology, and of recent developments in SPECT instrumentation for both clinical applications and basic biological research on animal models is described. (author)

Experience with a small animal hyperthermia ultrasound system (SAHUS): report on 83 tumours

International Nuclear Information System (INIS)

Novak, P; Moros, E G; Parry, J J; Rogers, B E; Myerson, R J; Zeug, A; Locke, J E; Rossin, R; Straube, W L; Singh, A K

2005-01-01

An external local ultrasound (US) system was developed to induce controlled hyperthermia of subcutaneously implanted tumours in small animals (e.g., mice and rats). It was designed to be compatible with a small animal positron emission tomography scanner (microPET) to facilitate studies of hyperthermia-induced tumour re-oxygenation using a PET radiopharmaceutical, but it is applicable for any small animal study requiring controlled heating. The system consists of an acrylic applicator bed with up to four independent 5 MHz planar disc US transducers of 1 cm in diameter, a four-channel radiofrequency (RF) generator, a multiple thermocouple thermometry unit, and a personal computer with custom monitoring and controlling software. Although the system presented here was developed to target tumours of up to 1 cm in diameter, the applicator design allows for different piezoelectric transducers to be exchanged and operated within the 3.5-6.5 MHz band to target different tumour sizes. Temperature feedback control software was developed on the basis of a proportional-integral-derivative (PID) approach when the measured temperatures were within a selectable temperature band about the target temperature. Outside this band, an on/off control action was applied. Perfused tissue-mimicking phantom experiments were performed to determine optimum controller gain constants, which were later employed successfully in animal experiments. The performance of the SAHUS (small animal hyperthermia ultrasound system) was tested using several tumour types grown in thighs of female nude (nu/nu) mice. To date, the system has successfully treated 83 tumours to target temperatures in the range of 41-43 deg. C for periods of 65 min on average

A small animal holding fixture system with positional reproducibility for longitudinal multimodal imaging

Energy Technology Data Exchange (ETDEWEB)

Kokuryo, Daisuke; Kimura, Yuichi; Obata, Takayuki; Yamaya, Taiga; Kawamura, Kazunori; Zhang, Ming-Rong; Kanno, Iwao; Aoki, Ichio, E-mail: ukimura@ieee.or [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)

2010-07-21

This study presents a combined small animal holding fixture system, termed a 'bridge capsule', which provides for small animal re-fixation with positional reproducibility. This system comprises separate holding fixtures for the head and lower body and a connecting part to a gas anesthesia system. A mouse is fixed in place by the combination of a head fixture with a movable part made from polyacetal resin, a lower body fixture made from vinyl-silicone and a holder for the legs and tail. For re-fixation, a similar posture could be maintained by the same holding fixtures and a constant distance between the head and lower body fixtures is maintained. Artifacts caused by the bridge capsule system were not observed on magnetic resonance (MRI) and positron emission tomography (PET) images. The average position differences of the spinal column and the iliac body before and after re-fixation for the same modality were approximately 1.1 mm. The difference between the MRI and PET images was approximately 1.8 mm for the lower body fixture after image registration using fiducial markers. This system would be useful for longitudinal, repeated and multimodal imaging experiments requiring similar animal postures.

Prompt gamma-ray imaging for small animals

Science.gov (United States)

Xu, Libai

Small animal imaging is recognized as a powerful discovery tool for small animal modeling of human diseases, which is providing an important clue to complete understanding of disease mechanisms and is helping researchers develop and test new treatments. The current small animal imaging techniques include positron emission tomography (PET), single photon emission tomography (SPECT), computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US). A new imaging modality called prompt gamma-ray imaging (PGI) has been identified and investigated primarily by Monte Carlo simulation. Currently it is suggested for use on small animals. This new technique could greatly enhance and extend the present capabilities of PET and SPECT imaging from ingested radioisotopes to the imaging of selected non-radioactive elements, such as Gd, Cd, Hg, and B, and has the great potential to be used in Neutron Cancer Therapy to monitor neutron distribution and neutron-capture agent distribution. This approach consists of irradiating small animals in the thermal neutron beam of a nuclear reactor to produce prompt gamma rays from the elements in the sample by the radiative capture (n, gamma) reaction. These prompt gamma rays are emitted in energies that are characteristic of each element and they are also produced in characteristic coincident chains. After measuring these prompt gamma rays by surrounding spectrometry array, the distribution of each element of interest in the sample is reconstructed from the mapping of each detected signature gamma ray by either electronic collimations or mechanical collimations. In addition, the transmitted neutrons from the beam can be simultaneously used for very sensitive anatomical imaging, which provides the registration for the elemental distributions obtained from PGI. The primary approach is to use Monte Carlo simulation methods either with the specific purpose code CEARCPG, developed at NC State University or with the general purpose

Positron Emission Tomography: Principles, Technology, and Recent Developments

Science.gov (United States)

Ziegler, Sibylle I.

2005-04-01

Positron emission tomography (PET) is a nuclear medical imaging technique for quantitative measurement of physiologic parameters in vivo (an overview of principles and applications can be found in [P.E. Valk, et al., eds. Positron Emission Tomography. Basic Science and Clinical Practice. 2003, Springer: Heidelberg]), based on the detection of small amounts of posi-tron-emitter-labelled biologic molecules. Various radiotracers are available for neuro-logical, cardiological, and oncological applications in the clinic and in research proto-cols. This overview describes the basic principles, technology, and recent develop-ments in PET, followed by a section on the development of a tomograph with ava-lanche photodiodes dedicated for small animal imaging as an example of efforts in the domain of high resolution tomographs.

New design of a quasi-monolithic detector module with DOI capability for small animal pet

International Nuclear Information System (INIS)

Chung, Yong Hyun; Lee, Seung-Jae; Baek, Cheol-Ha; Choi, Yong

2008-01-01

We report a new design of a detector module with depth of interaction (DOI) based on a quasi-monolithic LSO crystal, a multi-channel sensor, and maximum-likelihood position-estimation (MLPE) algorithm. Light transport and detection were modeled in a quasi-monolithic crystal using DETECT2000 code, with lookup tables (LUTs) built by simulation. Events were well separated by applying the MLPE method within 2.0 mm spatial resolution in both trans-axial and DOI directions. These results demonstrate that the proposed detector provides dependable positioning capability for small animal positron emission tomography (PET)

Evaluation of 3D reconstruction algorithms for a small animal PET camera

International Nuclear Information System (INIS)

Johnson, C.A.; Gandler, W.R.; Seidel, J.

1996-01-01

The use of paired, opposing position-sensitive phototube scintillation cameras (SCs) operating in coincidence for small animal imaging with positron emitters is currently under study. Because of the low sensitivity of the system even in 3D mode and the need to produce images with high resolution, it was postulated that a 3D expectation maximization (EM) reconstruction algorithm might be well suited for this application. We investigated four reconstruction algorithms for the 3D SC PET camera: 2D filtered back-projection (FBP), 2D ordered subset EM (OSEM), 3D reprojection (3DRP), and 3D OSEM. Noise was assessed for all slices by the coefficient of variation in a simulated uniform cylinder. Resolution was assessed from a simulation of 15 point sources in the warm background of the uniform cylinder. At comparable noise levels, the resolution achieved with OSEM (0.9-mm to 1.2-mm) is significantly better than that obtained with FBP or 3DRP (1.5-mm to 2.0-mm.) Images of a rat skull labeled with 18 F-fluoride suggest that 3D OSEM can improve image quality of a small animal PET camera

Small animal simultaneous PET/MRI: initial experiences in a 9.4 T microMRI

Energy Technology Data Exchange (ETDEWEB)

Maramraju, Sri Harsha; Ravindranath, Bosky; Vaska, Paul; Schlyer, David J [Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY (United States); Smith, S David; Schulz, Daniela [Medical Department, Brookhaven National Laboratory, Upton, NY (United States); Junnarkar, Sachin S; Rescia, Sergio [Instrumentation Division, Brookhaven National Laboratory, Upton, NY (United States); Stoll, Sean; Purschke, Martin L; Woody, Craig L [Physics Department, Brookhaven National Laboratory, Upton, NY (United States); Southekal, Sudeepti [Brigham and Women' s Hospital, Boston, MA (United States); Pratte, Jean-Francois, E-mail: schlyer@bnl.gov [Universite de Sherbrooke, Sherbrooke, Quebec (Canada)

2011-04-21

We developed a non-magnetic positron-emission tomography (PET) device based on the rat conscious animal PET that operates in a small-animal magnetic resonance imaging (MRI) scanner, thereby enabling us to carry out simultaneous PET/MRI studies. The PET detector comprises 12 detector blocks, each being a 4 x 8 array of lutetium oxyorthosilicate crystals (2.22 x 2.22 x 5 mm{sup 3}) coupled to a matching non-magnetic avalanche photodiode array. The detector blocks, housed in a plastic case, form a 38 mm inner diameter ring with an 18 mm axial extent. Custom-built MRI coils fit inside the positron-emission tomography (PET) device, operating in transceiver mode. The PET insert is integrated with a Bruker 9.4 T 210 mm clear-bore diameter MRI scanner. We acquired simultaneous PET/MR images of phantoms, of in vivo rat brain, and of cardiac-gated mouse heart using [{sup 11}C]raclopride and 2-deoxy-2-[{sup 18}F]fluoro-d-glucose PET radiotracers. There was minor interference between the PET electronics and the MRI during simultaneous operation, and small effects on the signal-to-noise ratio in the MR images in the presence of the PET, but no noticeable visual artifacts. Gradient echo and high-duty-cycle spin echo radio frequency (RF) pulses resulted in a 7% and a 28% loss in PET counts, respectively, due to high PET counts during the RF pulses that had to be gated out. The calibration of the activity concentration of PET data during MR pulsing is reproducible within less than 6%. Our initial results demonstrate the feasibility of performing simultaneous PET and MRI studies in adult rats and mice using the same PET insert in a small-bore 9.4 T MRI.

A prototype high-resolution animal positron tomograph with avalanche photodiode arrays and LSO crystals

International Nuclear Information System (INIS)

Ziegler, S.I.; Pichler, B.J.; Rafecas, M.; Schwaiger, M.

2001-01-01

To fully utilize positron emission tomography (PET) as a non-invasive tool for tissue characterization, dedicated instrumentation is being developed which is specially suited for imaging mice and rats. Semiconductor detectors, such as avalanche photodiodes (APDs), may offer an alternative to photomultiplier tubes for the readout of scintillation crystals. Since the scintillation characteristics of lutetium oxyorthosilicate (LSO) are well matched to APDs, the combination of LSO and APDs seems favourable, and the goal of this study was to build a positron tomograph with LSO-APD modules to prove the feasibility of such an approach. A prototype PET scanner based on APD readout of small, individual LSO crystals was developed for tracer studies in mice and rats. The tomograph consists of two sectors (86 mm distance), each comprising three LSO-APD modules, which can be rotated for the acquisition of complete projections. In each module, small LSO crystals (3.7 x 3.7 x 12 mm 3 ) are individually coupled to one channel within matrices containing 2 x 8 square APDs (2.6 x 2.6 mm 2 sensitive area per channel). The list-mode data are reconstructed with a penalized weighted least squares algorithm which includes the spatially dependent line spread function of the tomograph. Basic performance parameters were measured with phantoms and first experiments with rats and mice were conducted to introduce this methodology for biomedical imaging. The reconstructed field of view covers 68 mm, which is 80% of the total detector diameter. Image resolution was shown to be 2.4 mm within the whole reconstructed field of view. Using a lower energy threshold of 450 keV, the system sensitivity was 350 Hz/MBq for a line source in air in the centre of the field of view. In a water-filled cylinder of 4.6 cm diameter, the scatter fraction at the centre of the field of view was 16% (450 keV threshold). The count rate was linear up to 700 coincidence counts per second. In vivo studies of anaesthetized

Small-angle scattering of swift electrons and positrons in a crystal

International Nuclear Information System (INIS)

Kudrin, V.V.; Vorobiev, S.A.

1975-01-01

Features of small-angle scattering of charged particles by the crystal structure and two-dimensional angular distribution are studied on the basis of Monte-Carlo calculations of 20 MeV electron and positron transmission through a MgO single crystal. An accurate method for calculation of the charged particle scattering in a heterogeneous electron gas in the crystal is proposed. The analytical conditions under which the string-effect influences the small-angle scattering are derived and comparison is carried out with well-known experimental data. (author)

Development of computational small animal models and their applications in preclinical imaging and therapy research.

Science.gov (United States)

Xie, Tianwu; Zaidi, Habib

2016-01-01

The development of multimodality preclinical imaging techniques and the rapid growth of realistic computer simulation tools have promoted the construction and application of computational laboratory animal models in preclinical research. Since the early 1990s, over 120 realistic computational animal models have been reported in the literature and used as surrogates to characterize the anatomy of actual animals for the simulation of preclinical studies involving the use of bioluminescence tomography, fluorescence molecular tomography, positron emission tomography, single-photon emission computed tomography, microcomputed tomography, magnetic resonance imaging, and optical imaging. Other applications include electromagnetic field simulation, ionizing and nonionizing radiation dosimetry, and the development and evaluation of new methodologies for multimodality image coregistration, segmentation, and reconstruction of small animal images. This paper provides a comprehensive review of the history and fundamental technologies used for the development of computational small animal models with a particular focus on their application in preclinical imaging as well as nonionizing and ionizing radiation dosimetry calculations. An overview of the overall process involved in the design of these models, including the fundamental elements used for the construction of different types of computational models, the identification of original anatomical data, the simulation tools used for solving various computational problems, and the applications of computational animal models in preclinical research. The authors also analyze the characteristics of categories of computational models (stylized, voxel-based, and boundary representation) and discuss the technical challenges faced at the present time as well as research needs in the future.

Development of computational small animal models and their applications in preclinical imaging and therapy research

Energy Technology Data Exchange (ETDEWEB)

Xie, Tianwu [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva 4 CH-1211 (Switzerland); Zaidi, Habib, E-mail: habib.zaidi@hcuge.ch [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva 4 CH-1211 (Switzerland); Geneva Neuroscience Center, Geneva University, Geneva CH-1205 (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen 9700 RB (Netherlands)

2016-01-15

The development of multimodality preclinical imaging techniques and the rapid growth of realistic computer simulation tools have promoted the construction and application of computational laboratory animal models in preclinical research. Since the early 1990s, over 120 realistic computational animal models have been reported in the literature and used as surrogates to characterize the anatomy of actual animals for the simulation of preclinical studies involving the use of bioluminescence tomography, fluorescence molecular tomography, positron emission tomography, single-photon emission computed tomography, microcomputed tomography, magnetic resonance imaging, and optical imaging. Other applications include electromagnetic field simulation, ionizing and nonionizing radiation dosimetry, and the development and evaluation of new methodologies for multimodality image coregistration, segmentation, and reconstruction of small animal images. This paper provides a comprehensive review of the history and fundamental technologies used for the development of computational small animal models with a particular focus on their application in preclinical imaging as well as nonionizing and ionizing radiation dosimetry calculations. An overview of the overall process involved in the design of these models, including the fundamental elements used for the construction of different types of computational models, the identification of original anatomical data, the simulation tools used for solving various computational problems, and the applications of computational animal models in preclinical research. The authors also analyze the characteristics of categories of computational models (stylized, voxel-based, and boundary representation) and discuss the technical challenges faced at the present time as well as research needs in the future.

Development of computational small animal models and their applications in preclinical imaging and therapy research

International Nuclear Information System (INIS)

Xie, Tianwu; Zaidi, Habib

2016-01-01

The development of multimodality preclinical imaging techniques and the rapid growth of realistic computer simulation tools have promoted the construction and application of computational laboratory animal models in preclinical research. Since the early 1990s, over 120 realistic computational animal models have been reported in the literature and used as surrogates to characterize the anatomy of actual animals for the simulation of preclinical studies involving the use of bioluminescence tomography, fluorescence molecular tomography, positron emission tomography, single-photon emission computed tomography, microcomputed tomography, magnetic resonance imaging, and optical imaging. Other applications include electromagnetic field simulation, ionizing and nonionizing radiation dosimetry, and the development and evaluation of new methodologies for multimodality image coregistration, segmentation, and reconstruction of small animal images. This paper provides a comprehensive review of the history and fundamental technologies used for the development of computational small animal models with a particular focus on their application in preclinical imaging as well as nonionizing and ionizing radiation dosimetry calculations. An overview of the overall process involved in the design of these models, including the fundamental elements used for the construction of different types of computational models, the identification of original anatomical data, the simulation tools used for solving various computational problems, and the applications of computational animal models in preclinical research. The authors also analyze the characteristics of categories of computational models (stylized, voxel-based, and boundary representation) and discuss the technical challenges faced at the present time as well as research needs in the future

Positron Emission Tomography imaging with the SmartPET system

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool, Liverpool, Merseyside L69 7ZE (United Kingdom)], E-mail: cooperrj@ornl.gov; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P.; Mather, A.R. [Department of Physics, University of Liverpool, Liverpool, Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom)

2009-07-21

The Small Animal Reconstruction Tomograph for Positron Emission Tomography (SmartPET) project is the development of a small animal Positron Emission Tomography (PET) demonstrator based on the use of High-Purity Germanium (HPGe) detectors and state of the art digital electronics. The experimental results presented demonstrate the current performance of this unique system. By performing high precision measurements of one of the SmartPET HPGe detectors with a range of finely collimated gamma-ray beams the response of the detector as a function of gamma-ray interaction position has been quantified, facilitating the development of parametric Pulse Shape Analysis (PSA) techniques and algorithms for the correction of imperfections in detector performance. These algorithms have then been applied to data from PET imaging measurements using two such detectors in conjunction with a specially designed rotating gantry. In this paper we show how the use of parametric PSA approaches allows over 60% of coincident events to be processed and how the nature and complexity of an event has direct implications for the quality of the resulting image.

Small animal radiotherapy research platforms

Energy Technology Data Exchange (ETDEWEB)

Verhaegen, Frank; Granton, Patrick [Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Tryggestad, Erik, E-mail: frank.verhaegen@maastro.nl [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21231 (United States)

2011-06-21

Advances in conformal radiation therapy and advancements in pre-clinical radiotherapy research have recently stimulated the development of precise micro-irradiators for small animals such as mice and rats. These devices are often kilovolt x-ray radiation sources combined with high-resolution CT imaging equipment for image guidance, as the latter allows precise and accurate beam positioning. This is similar to modern human radiotherapy practice. These devices are considered a major step forward compared to the current standard of animal experimentation in cancer radiobiology research. The availability of this novel equipment enables a wide variety of pre-clinical experiments on the synergy of radiation with other therapies, complex radiation schemes, sub-target boost studies, hypofractionated radiotherapy, contrast-enhanced radiotherapy and studies of relative biological effectiveness, to name just a few examples. In this review we discuss the required irradiation and imaging capabilities of small animal radiation research platforms. We describe the need for improved small animal radiotherapy research and highlight pioneering efforts, some of which led recently to commercially available prototypes. From this, it will be clear that much further development is still needed, on both the irradiation side and imaging side. We discuss at length the need for improved treatment planning tools for small animal platforms, and the current lack of a standard therein. Finally, we mention some recent experimental work using the early animal radiation research platforms, and the potential they offer for advancing radiobiology research. (topical review)

Small animal radiotherapy research platforms

Science.gov (United States)

Verhaegen, Frank; Granton, Patrick; Tryggestad, Erik

2011-06-01

Advances in conformal radiation therapy and advancements in pre-clinical radiotherapy research have recently stimulated the development of precise micro-irradiators for small animals such as mice and rats. These devices are often kilovolt x-ray radiation sources combined with high-resolution CT imaging equipment for image guidance, as the latter allows precise and accurate beam positioning. This is similar to modern human radiotherapy practice. These devices are considered a major step forward compared to the current standard of animal experimentation in cancer radiobiology research. The availability of this novel equipment enables a wide variety of pre-clinical experiments on the synergy of radiation with other therapies, complex radiation schemes, sub-target boost studies, hypofractionated radiotherapy, contrast-enhanced radiotherapy and studies of relative biological effectiveness, to name just a few examples. In this review we discuss the required irradiation and imaging capabilities of small animal radiation research platforms. We describe the need for improved small animal radiotherapy research and highlight pioneering efforts, some of which led recently to commercially available prototypes. From this, it will be clear that much further development is still needed, on both the irradiation side and imaging side. We discuss at length the need for improved treatment planning tools for small animal platforms, and the current lack of a standard therein. Finally, we mention some recent experimental work using the early animal radiation research platforms, and the potential they offer for advancing radiobiology research.

Small animal radiotherapy research platforms

International Nuclear Information System (INIS)

Verhaegen, Frank; Granton, Patrick; Tryggestad, Erik

2011-01-01

Advances in conformal radiation therapy and advancements in pre-clinical radiotherapy research have recently stimulated the development of precise micro-irradiators for small animals such as mice and rats. These devices are often kilovolt x-ray radiation sources combined with high-resolution CT imaging equipment for image guidance, as the latter allows precise and accurate beam positioning. This is similar to modern human radiotherapy practice. These devices are considered a major step forward compared to the current standard of animal experimentation in cancer radiobiology research. The availability of this novel equipment enables a wide variety of pre-clinical experiments on the synergy of radiation with other therapies, complex radiation schemes, sub-target boost studies, hypofractionated radiotherapy, contrast-enhanced radiotherapy and studies of relative biological effectiveness, to name just a few examples. In this review we discuss the required irradiation and imaging capabilities of small animal radiation research platforms. We describe the need for improved small animal radiotherapy research and highlight pioneering efforts, some of which led recently to commercially available prototypes. From this, it will be clear that much further development is still needed, on both the irradiation side and imaging side. We discuss at length the need for improved treatment planning tools for small animal platforms, and the current lack of a standard therein. Finally, we mention some recent experimental work using the early animal radiation research platforms, and the potential they offer for advancing radiobiology research. (topical review)

Positron emission tomography

International Nuclear Information System (INIS)

Iio, Masahiro

1982-01-01

Utilization of positron emission tomography was reviewed in relation to construction and planned construction of small-size medical cyclotrons, planned construction of positron cameras and utilization of short-lived radionuclides. (Chiba, N.)

Anesthesia condition for 18F-FDG imaging of lung metastasis tumors using small animal PET

International Nuclear Information System (INIS)

Woo, Sang-Keun; Lee, Tae Sup; Kim, Kyeong Min; Kim, June-Youp; Jung, Jae Ho; Kang, Joo Hyun; Cheon, Gi Jeong; Choi, Chang Woon; Lim, Sang Moo

2008-01-01

Small animal positron emission tomography (PET) with 18 F-FDG has been increasingly used for tumor imaging in the murine model. The aim of this study was to establish the anesthesia condition for imaging of lung metastasis tumor using small animal 18 F-FDG PET. Methods: To determine the impact of anesthesia on 18 F-FDG distribution in normal mice, five groups were studied under the following conditions: no anesthesia, ketamine and xylazine (Ke/Xy), 0.5% isoflurane (Iso 0.5), 1% isoflurane (Iso 1) and 2% isoflurane (Iso 2). The ex vivo counting, standard uptake value (SUV) image and glucose SUV of 18 F-FDG in various tissues were evaluated. The 18 F-FDG images in the lung metastasis tumor model were obtained under no anesthesia, Ke/Xy and Iso 0.5, and registered with CT image to clarify the tumor region. Results: Blood glucose concentration and muscle uptake of 18 F-FDG in the Ke/Xy group markedly increased more than in the other groups. The Iso 2 group increased 18 F-FDG uptake in heart compared with the other groups. The Iso 0.5 anesthesized group showed the lowest 18 F-FDG uptake in heart and chest wall. The small size of lung metastasis tumor (2 mm) was clearly visualized by 18 F-FDG image with the Iso 0.5 anesthesia. Conclusion: Small animal 18 F-FDG PET imaging with Iso 0.5 anesthesia was appropriate for the detection of lung metastasis tumor. To acquire 18 F-FDG PET images with small animal PET, the type and level of anesthetic should be carefully considered to be suitable for the visualization of target tissue in the experimental model

Energy resolution of a four-layer depth of interaction detector block for small animal PET

International Nuclear Information System (INIS)

Tsuda, Tomoaki; Kawai, Hideyuki; Orita, Narimichi; Murayama, Hideo; Yoshida, Eiji; Inadama, Naoko; Yamaya, Taiga; Omura, Tomohide

2004-01-01

We are now planning to develop a positron emission tomograph dedicated to small animals such as rats and mice which meets the demand for higher sensitivity. We proposed a new depth of interaction (DOI) detector arrangement to obtain DOI information by using a four-layer detector with all the same crystal elements. In this DOI detector, we control the behavior of scintillation photons by inserting the reflectors between crystal elements so that the DOI information of four layers can be extracted from one two-dimensional (2D) position histogram made by Anger-type calculation. In this work, we evaluate the energy resolution of this four-layer DOI detector. (author)

Anesthesia condition for {sup 18}F-FDG imaging of lung metastasis tumors using small animal PET

Energy Technology Data Exchange (ETDEWEB)

Woo, Sang-Keun; Lee, Tae Sup; Kim, Kyeong Min; Kim, June-Youp; Jung, Jae Ho; Kang, Joo Hyun [Division of Nuclear Medicine and RI Application, Korea Institute of Radiological and Medical Sciences (KIRAMS), Nowon-Gu, Seoul 139-706 (Korea, Republic of); Cheon, Gi Jeong [Division of Nuclear Medicine and RI Application, Korea Institute of Radiological and Medical Sciences (KIRAMS), Nowon-Gu, Seoul 139-706 (Korea, Republic of); Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences (KIRAMS), Nowon-Gu, Seoul 139-706 (Korea, Republic of)], E-mail: larry@kcch.re.kr; Choi, Chang Woon; Lim, Sang Moo [Division of Nuclear Medicine and RI Application, Korea Institute of Radiological and Medical Sciences (KIRAMS), Nowon-Gu, Seoul 139-706 (Korea, Republic of); Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences (KIRAMS), Nowon-Gu, Seoul 139-706 (Korea, Republic of)

2008-01-15

Small animal positron emission tomography (PET) with {sup 18}F-FDG has been increasingly used for tumor imaging in the murine model. The aim of this study was to establish the anesthesia condition for imaging of lung metastasis tumor using small animal {sup 18}F-FDG PET. Methods: To determine the impact of anesthesia on {sup 18}F-FDG distribution in normal mice, five groups were studied under the following conditions: no anesthesia, ketamine and xylazine (Ke/Xy), 0.5% isoflurane (Iso 0.5), 1% isoflurane (Iso 1) and 2% isoflurane (Iso 2). The ex vivo counting, standard uptake value (SUV) image and glucose SUV of {sup 18}F-FDG in various tissues were evaluated. The {sup 18}F-FDG images in the lung metastasis tumor model were obtained under no anesthesia, Ke/Xy and Iso 0.5, and registered with CT image to clarify the tumor region. Results: Blood glucose concentration and muscle uptake of {sup 18}F-FDG in the Ke/Xy group markedly increased more than in the other groups. The Iso 2 group increased {sup 18}F-FDG uptake in heart compared with the other groups. The Iso 0.5 anesthesized group showed the lowest {sup 18}F-FDG uptake in heart and chest wall. The small size of lung metastasis tumor (2 mm) was clearly visualized by {sup 18}F-FDG image with the Iso 0.5 anesthesia. Conclusion: Small animal {sup 18}F-FDG PET imaging with Iso 0.5 anesthesia was appropriate for the detection of lung metastasis tumor. To acquire {sup 18}F-FDG PET images with small animal PET, the type and level of anesthetic should be carefully considered to be suitable for the visualization of target tissue in the experimental model.

Small animal imaging. Basics and practical guide

Energy Technology Data Exchange (ETDEWEB)

Kiessling, Fabian [Aachen Univ. (RWTH) (Germany). Chair of Experimental Molecular Imaging; Pichler, Bernd J. (eds.) [Tuebingen Univ. (Germany). Lab. for Preclinical Imaging and Imaging Technology of the Werner Siemens-Foundation

2011-07-01

Small animal imaging has been recognized as an important tool in preclinical research. Nevertheless, the results of non-invasive imaging are often disappointing owing to choice of a suboptimal imaging modality and/or shortcomings in study design, experimental setup, and data evaluation. This textbook is a practical guide to the use of non-invasive imaging in preclinical research. Each of the available imaging modalities is discussed in detail, with the assistance of numerous informative illustrations. In addition, many useful hints are provided on the installation of a small animal unit, study planning, animal handling, and the cost-effective performance of small animal imaging. Cross-calibration methods, data postprocessing, and special imaging applications are also considered in depth. This is the first book to cover all the practical basics in small animal imaging, and it will prove an invaluable aid for researchers, students, and technicians. (orig.)

Small animal imaging. Basics and practical guide

International Nuclear Information System (INIS)

Kiessling, Fabian; Pichler, Bernd J.

2011-01-01

Small animal imaging has been recognized as an important tool in preclinical research. Nevertheless, the results of non-invasive imaging are often disappointing owing to choice of a suboptimal imaging modality and/or shortcomings in study design, experimental setup, and data evaluation. This textbook is a practical guide to the use of non-invasive imaging in preclinical research. Each of the available imaging modalities is discussed in detail, with the assistance of numerous informative illustrations. In addition, many useful hints are provided on the installation of a small animal unit, study planning, animal handling, and the cost-effective performance of small animal imaging. Cross-calibration methods, data postprocessing, and special imaging applications are also considered in depth. This is the first book to cover all the practical basics in small animal imaging, and it will prove an invaluable aid for researchers, students, and technicians. (orig.)

High-resolution SPECT for small-animal imaging

International Nuclear Information System (INIS)

Qi Yujin

2006-01-01

This article presents a brief overview of the development of high-resolution SPECT for small-animal imaging. A pinhole collimator has been used for high-resolution animal SPECT to provide better spatial resolution and detection efficiency in comparison with a parallel-hole collimator. The theory of imaging characteristics of the pinhole collimator is presented and the designs of the pinhole aperture are discussed. The detector technologies used for the development of small-animal SPECT and the recent advances are presented. The evolving trend of small-animal SPECT is toward a multi-pinhole and a multi-detector system to obtain a high resolution and also a high detection efficiency. (authors)

Positron range in PET imaging: an alternative approach for assessing and correcting the blurring

DEFF Research Database (Denmark)

Jødal, Lars; Le Loirec, Cindy; Champion, Christophe

2012-01-01

Background: Positron range impairs resolution in PET imaging, especially for high-energy emitters and for small-animal PET. De-blurring in image reconstruction is possible if the blurring distribution is known. Further, the percentage of annihilation events within a given distance from the point...... on allowed-decay isotopes. Methods: It is argued that blurring at the detection level should not be described by positron range r, but instead the 2D-projected distance δ (equal to the closest distance between decay and line-of-response). To determine these 2D distributions, results from a dedicated positron...... is important for improved resolution in PET imaging. Relevant distributions for positron range have been derived for seven isotopes. Distributions for other allowed-decay isotopes may be estimated with the above formulas....

Glucose metabolism in small subcortical structures in Parkinson's disease

DEFF Research Database (Denmark)

Borghammer, Per; Hansen, Søren B; Eggers, Carsten

2012-01-01

Evidence from experimental animal models of Parkinson's disease (PD) suggests a characteristic pattern of metabolic perturbation in discrete, very small basal ganglia structures. These structures are generally too small to allow valid investigation by conventional positron emission tomography (PE...

Use of scanner characteristics in iterative image reconstruction for high-resolution positron emission tomography studies of small animals

Energy Technology Data Exchange (ETDEWEB)

Brix, G. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany); Doll, J. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany); Bellemann, M.E. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany); Trojan, H. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany); Haberkorn, U. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany); Schmidlin, P. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany); Ostertag, H. [Research Program ``Radiological Diagnostics and Therapy``, German Cancer Research Center (DKFZ), Heidelberg (Germany)

1997-07-01

The purpose of this work was to improve of the spatial resolution of a whole-body PET system for experimental studies of small animals by incorporation of scanner characteristics into the process of iterative image reconstruction. The image-forming characteristics of the PET camera were characterized by a spatially variant line-spread function (LSF), which was determined from 49 activated copper-64 line sources positioned over a field of view (FOV) of 21.0 cm. During the course of iterative image reconstruction, the forward projection of the estimated image was blurred with the LSF at each iteration step before the estimated projections were compared with the measured projections. Moreover, imaging studies of a rat and two nude mice were performed to evaluate the imaging properties of our approach in vivo. The spatial resolution of the scanner perpendicular to the direction of projection could be approximated by a one-dimensional Gaussian-shaped LSF with a full-width at half-maximum increasing from 6.5 mm at the centre to 6.7 mm at a radial distance of 10.5 cm. The incorporation of this blurring kernel into the iteration formula resulted in a significantly improved spatial resolution of about 3.9 mm over the examined FOV. As demonstrated by the phantom and the animal experiments, the high-resolution algorithm not only led to a better contrast resolution in the reconstructed emission scans but also improved the accuracy for quantitating activity concentrations in small tissue structures without leading to an amplification of image noise or image mottle. The presented data-handling strategy incorporates the image restoration step directly into the process of algebraic image reconstruction and obviates the need for ill-conditioned ``deconvolution`` procedures to be performed on the projections or on the reconstructed image. In our experience, the proposed algorithm is of special interest in experimental studies of small animals. (orig./AJ). With 9 figs.

Use of scanner characteristics in iterative image reconstruction for high-resolution positron emission tomography studies of small animals

International Nuclear Information System (INIS)

Brix, G.; Doll, J.; Bellemann, M.E.; Trojan, H.; Haberkorn, U.; Schmidlin, P.; Ostertag, H.

1997-01-01

The purpose of this work was to improve of the spatial resolution of a whole-body PET system for experimental studies of small animals by incorporation of scanner characteristics into the process of iterative image reconstruction. The image-forming characteristics of the PET camera were characterized by a spatially variant line-spread function (LSF), which was determined from 49 activated copper-64 line sources positioned over a field of view (FOV) of 21.0 cm. During the course of iterative image reconstruction, the forward projection of the estimated image was blurred with the LSF at each iteration step before the estimated projections were compared with the measured projections. Moreover, imaging studies of a rat and two nude mice were performed to evaluate the imaging properties of our approach in vivo. The spatial resolution of the scanner perpendicular to the direction of projection could be approximated by a one-dimensional Gaussian-shaped LSF with a full-width at half-maximum increasing from 6.5 mm at the centre to 6.7 mm at a radial distance of 10.5 cm. The incorporation of this blurring kernel into the iteration formula resulted in a significantly improved spatial resolution of about 3.9 mm over the examined FOV. As demonstrated by the phantom and the animal experiments, the high-resolution algorithm not only led to a better contrast resolution in the reconstructed emission scans but also improved the accuracy for quantitating activity concentrations in small tissue structures without leading to an amplification of image noise or image mottle. The presented data-handling strategy incorporates the image restoration step directly into the process of algebraic image reconstruction and obviates the need for ill-conditioned ''deconvolution'' procedures to be performed on the projections or on the reconstructed image. In our experience, the proposed algorithm is of special interest in experimental studies of small animals. (orig./AJ). With 9 figs

High resolution positron tomography

International Nuclear Information System (INIS)

Brownell, G.L.; Burnham, C.A.

1982-01-01

The limits of spatial resolution in practical positron tomography are examined. The four factors that limit spatial resolution are: positron range; small angle deviation; detector dimensions and properties; statistics. Of these factors, positron range may be considered the fundamental physical limitation since it is independent of instrument properties. The other factors are to a greater or lesser extent dependent on the design of the tomograph

A small animal PET prototype based on Silicon Photomultipliers

International Nuclear Information System (INIS)

Marcatili, S; Belcari, N.; Bisogni, M.G.; Del Guerra, A.; Collazuol, G.; Pedreschi, E.; Spinella, F.; Sportelli, G.; Marzocca, C.

2011-01-01

Next generation PET scanners should full fill very high requirements in terms of spatial, energy and timing resolution. Modern scanner performances are inherently limited by the use of standard photomultiplier tubes. The use of Silicon Photomultiplier (Si P M) matrices is proposed for the construction of a small animal PET system consisting of two detector heads based on Lyso continuos crystals. The use of large area multi-pixel Silicon Photomultiplier (Si P M) detectors requires the development of a multichannel Digital Acquisition system (DAQ) as well as of a dedicated front-end in order not to degrade the intrinsic detector capabilities. At the University of Pisa and INFN Pisa we developed a DAQ board for the read-out of 2 64-pixel Si P M matrices in time coincidence for Positron Emission Tomography (PET) applications. The proof of principles is based on 64-pixel detectors, but the whole system has been conceived to be easily scalable to a higher number of channels. Here we describe the Group-V INFN DASi P M 2 (Development and Application of Si P M) project and related results.

Effects of quantum chemistry models for bound electrons on positron annihilation spectra for atoms and small molecules

International Nuclear Information System (INIS)

Wang Feng; Ma Xiaoguang; Selvam, Lalitha; Gribakin, Gleb; Surko, Clifford M

2012-01-01

The Doppler-shift spectra of the γ-rays from positron annihilation in molecules were determined by using the momentum distribution of the annihilation electron–positron pair. The effect of the positron wavefunction on spectra was analysed in a recent paper (Green et al 2012 New J. Phys. 14 035021). In this companion paper, we focus on the dominant contribution to the spectra, which arises from the momenta of the bound electrons. In particular, we use computational quantum chemistry models (Hartree–Fock with two basis sets and density functional theory (DFT)) to calculate the wavefunctions of the bound electrons. Numerical results are presented for noble gases and small molecules such as H 2 , N 2 , O 2 , CH 4 and CF 4 . The calculations reveal relatively small effects on the Doppler-shift spectra from the level of inclusion of electron correlation energy in the models. For atoms, the difference in the full-width at half-maximum of the spectra obtained using the Hartree–Fock and DFT models does not exceed 2%. For molecules the difference can be much larger, reaching 8% for some molecular orbitals. These results indicate that the predicted positron annihilation spectra for molecules are generally more sensitive to inclusion of electron correlation energies in the quantum chemistry model than the spectra for atoms are. (paper)

Small Animal [18F]FDG PET Imaging for Tumor Model Study

International Nuclear Information System (INIS)

Woo, Sang Keun; Kim, Kyeong Min; Cheon, Gi Jeong

2008-01-01

PET allows non-invasive, quantitative and repetitive imaging of biological function in living animals. Small animal PET imaging with [ 18 F]FDG has been successfully applied to investigation of metabolism, receptor, ligand interactions, gene expression, adoptive cell therapy and somatic gene therapy. Experimental condition of animal handling impacts on the biodistribution of [ 18 F]FDG in small animal study. The small animal PET and CT images were registered using the hardware fiducial markers and small animal contour point. Tumor imaging in small animal with small animal [ 18 F]FDG PET should be considered fasting, warming, and isoflurane anesthesia level. Registered imaging with small animal PET and CT image could be useful for the detection of tumor. Small animal experimental condition of animal handling and registration method will be of most importance for small lesion detection of metastases tumor model

Positron emitter labeled enzyme inhibitors

International Nuclear Information System (INIS)

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.; Langstrom, B.

1990-01-01

This invention involves a new strategy for imagining and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography

Is the positron a light proton. Contrasts of positron/proton analogies in small molecules

International Nuclear Information System (INIS)

Cade, P.E.; Kao, C.-M.

1982-01-01

The nature of positron behavior in [M - :e + ] systems is explored. Here M - is a molecular anion which combines with a proton to form a stable system, HM. The sharp distinction between the positron and proton dynamics does not entirely remove common characteristics of these systems. Examples are given for HM versus [M - :e + ] systems with M - = (H - , SH - , CN - , and N 3- ). In addition, the possibilities of a 'positronium' bond versus a hydrogen bond are discussed. (Auth.)

Advanced Small Animal Conformal Radiation Therapy Device.

Science.gov (United States)

Sharma, Sunil; Narayanasamy, Ganesh; Przybyla, Beata; Webber, Jessica; Boerma, Marjan; Clarkson, Richard; Moros, Eduardo G; Corry, Peter M; Griffin, Robert J

2017-02-01

We have developed a small animal conformal radiation therapy device that provides a degree of geometrical/anatomical targeting comparable to what is achievable in a commercial animal irradiator. small animal conformal radiation therapy device is capable of producing precise and accurate conformal delivery of radiation to target as well as for imaging small animals. The small animal conformal radiation therapy device uses an X-ray tube, a robotic animal position system, and a digital imager. The system is in a steel enclosure with adequate lead shielding following National Council on Radiation Protection and Measurements 49 guidelines and verified with Geiger-Mueller survey meter. The X-ray source is calibrated following AAPM TG-61 specifications and mounted at 101.6 cm from the floor, which is a primary barrier. The X-ray tube is mounted on a custom-made "gantry" and has a special collimating assembly system that allows field size between 0.5 mm and 20 cm at isocenter. Three-dimensional imaging can be performed to aid target localization using the same X-ray source at custom settings and an in-house reconstruction software. The small animal conformal radiation therapy device thus provides an excellent integrated system to promote translational research in radiation oncology in an academic laboratory. The purpose of this article is to review shielding and dosimetric measurement and highlight a few successful studies that have been performed to date with our system. In addition, an example of new data from an in vivo rat model of breast cancer is presented in which spatially fractionated radiation alone and in combination with thermal ablation was applied and the therapeutic benefit examined.

Thermoacoustic Molecular Imaging of Small Animals

Directory of Open Access Journals (Sweden)

Robert A. Kruger

2003-04-01

Full Text Available We have designed, constructed, and tested a thermoacoustic computed tomography (TCT scanner for imaging optical absorption in small animals in three dimensions. The device utilizes pulsed laser irradiation (680–1064 nm and a unique, 128-element transducer array. We quantified the isotropic spatial resolution of this scanner to be 0.35 mm. We describe a dual-wavelength subtraction technique for isolating optical dyes with TCT. Phantom experiments demonstrate that we can detect 5 fmol of a near-infrared dye (indocyanine green, ICG in a 1-ML volume using dual-wavelength subtraction. Initial TCT imaging in phantoms and in two sacrificed mice suggests that three-dimensional, optical absorption patterns in small animals can be detected with an order of magnitude better spatial resolution and an order of magnitude better low-contrast detectability in small animals when compared to fluorescence imaging or diffusion optical tomography.

Animals In Synchrotrons: Overcoming Challenges For High-Resolution, Live, Small-Animal Imaging

International Nuclear Information System (INIS)

Donnelley, Martin; Parsons, David; Morgan, Kaye; Siu, Karen

2010-01-01

Physiological studies in small animals can be complicated, but the complexity is increased dramatically when performing live-animal synchrotron X-ray imaging studies. Our group has extensive experience in high-resolution live-animal imaging at the Japanese SPring-8 synchrotron, primarily examining airways in two-dimensions. These experiments normally image an area of 1.8 mmx1.2 mm at a pixel resolution of 0.45 μm and are performed with live, intact, anaesthetized mice.There are unique challenges in this experimental setting. Importantly, experiments must be performed in an isolated imaging hutch not specifically designed for small-animal imaging. This requires equipment adapted to remotely monitor animals, maintain their anesthesia, and deliver test substances while collecting images. The horizontal synchrotron X-ray beam has a fixed location and orientation that limits experimental flexibility. The extremely high resolution makes locating anatomical regions-of-interest slow and can result in a high radiation dose, and at this level of magnification small animal movements produce motion-artifacts that can render acquired images unusable. Here we describe our experimental techniques and how we have overcome several challenges involved in performing live mouse synchrotron imaging.Experiments have tested different mouse strains, with hairless strains minimizing overlying skin and hair artifacts. Different anesthetics have also be trialed due to the limited choices available at SPring-8. Tracheal-intubation methods have been refined and controlled-ventilation is now possible using a specialized small-animal ventilator. With appropriate animal restraint and respiratory-gating, motion-artifacts have been minimized. The animal orientation (supine vs. head-high) also appears to affect animal physiology, and can alter image quality. Our techniques and image quality at SPring-8 have dramatically improved and in the near future we plan to translate this experience to the

Cardiac positron tomography

International Nuclear Information System (INIS)

Geltmann, E.M.; Roberts, R.; Sobel, B.E.

1980-01-01

Positron emission tomography (PET) performed after the administration of the positron-emitting radionuclides carbon-11 ( 11 C), nitrogen-13 ( 13 N), oxygen-15 ( 15 O) and fluorine-18 ( 18 F) has permitted the improved noninvasive assessment of the regional myocardial metabolism of normal physiologic substrates and intermediates and their cogeners. In experimental animals, the rate of oxidation of 11 C-palmitate correlates closely with other indexes of oxygen consumption, and the extraction of 11 C-palmitate (like that of 18 F-fatty acids and 18 F-fluoredoxyglucose) ist markedly diminished in regions of myocardial ischemia. In both experimental animals and in patients, myocardial infarct site and size, determined by positron emission tomography after the intravenous injection of 11 C-palmitate, correlate closely with the electrocardiographic infarct locus and enzymatically estimated infarct size as well as with the location and extent of regional left ventricular wall motion abnormalities. PET offers promise for assessment of flow as well despite the complexities involved. PET with 13 NH 3 appears to provide one useful qualitative index, although this tracer ist actively metabolized. Because of the quantitative capabilities of positron emission tomography and the rapid progress which is being made in the development of fast scan, multi-slice, and gated instrumentation, this technique is likely to facilitate improved understanding and characterization of regional myocardial metabolism and blood flow in man under physiological and pathophysiological conditions. (orig.) [de

The role of positron emission tomography in mediastinal staging of patients with non-small cell lung cancer.

Science.gov (United States)

d'Amico, Andrea; Turska-d'Amico, Maria; Jarzab, Barbara; Zielinski, Marcin

2015-01-01

To examine the diagnostic accuracy of positron emission tomography/computed tomography in evaluating the mediastinum of patients with non-small cell lung cancer compared to histopathology results. The prospective study was conducted at the Department of Thoracic Surgery of the Pulmonary Hospital in Zakopane, Poland, from September 2008 to August 2012 and comprised patients with radiologically-suspected lung cancer. All patients underwent histological verification by either mediastinoscopy alone or thoracotomy with mediastinal lymphanedectomy. Computed tomography and positron emission tomography/computed tomography data sets were compared with the results of the histopathology examinations. There were 80 patients in the study. In the diagnosis of mediastinal lymph nodes, computed tomography was able to detect 9(11.25%) true-positive, 17(21.25%) false-positive, 40(50%) true-negative and 14(17.5%) false-negative cases. The sensitivity, specificity and accuracy of the method were found to be 39%, 70% and 61% respectively, while the positive and negative predictive values were 35% and 74%. Positron emission tomography/computed tomography yielded 15(18.75%) true-positive, 12(15%) false-positive, 46(57.5%) true-negative and 7(8.75%) false-negative cases. Sensitivity was 68% while specificity was 79%. The accuracy was 96%, and the positive and negative predictive values were 55% and 87% respectively. Positron emission tomography/computed tomography had higher diagnostic accuracy than computed tomography in assessing mediastinal lymph nodes of patients with non-small cell lung cancer. However, a positive test requires histopathology confirmation.

Test–retest repeatability of quantitative cardiac 11C-meta-hydroxyephedrine measurements in rats by small animal positron emission tomography

International Nuclear Information System (INIS)

Thackeray, James T.; Renaud, Jennifer M.; Kordos, Myra; Klein, Ran; Kemp, Robert A. de; Beanlands, Rob S.B.; DaSilva, Jean N.

2013-01-01

Introduction: The norepinephrine analogue 11 C-meta-hydroxyephedrine (HED) has been used to interrogate sympathetic neuronal reuptake in cardiovascular disease. Application for longitudinal studies in small animal models of disease necessitates an understanding of test–retest variability. This study evaluated the repeatability of multiple quantitative cardiac measurements of HED retention and washout and the pharmacological response to reuptake blockade and enhanced norepinephrine levels. Methods: Small animal PET images were acquired over 60 min following HED administration to healthy male Sprague Dawley rats. Paired test and retest scans were undertaken in individual animals over 7 days. Additional HED scans were conducted following administration of norepinephrine reuptake inhibitor desipramine or continuous infusion of exogenous norepinephrine. HED retention was quantified by retention index, standardized uptake value (SUV), monoexponential and one-compartment washout. Plasma and cardiac norepinephrine were measured by high performance liquid chromatography. Results: Test retest variability was lower for retention index (15% ± 12%) and SUV (19% ± 15%) as compared to monoexponential washout rates (21% ± 13%). Desipramine pretreatment reduced myocardial HED retention index by 69% and SUV by 85%. Chase treatment with desipramine increased monoexponential HED washout by 197% compared to untreated controls. Norepinephrine infusion dose-dependently reduced HED accumulation, reflected by both retention index and SUV, with a corresponding increase in monoexponential washout. Plasma and cardiac norepinephrine levels correlated with HED quantitative measurements. Conclusion: The repeatability of HED retention index, SUV, and monoexponential washout supports its suitability for longitudinal PET studies in rats. Uptake and washout of HED are sensitive to acute increases in norepinephrine concentration

Clinical aspects of toxoplasmosis in small animal

Directory of Open Access Journals (Sweden)

André Luiz Baptista Galvão

2014-02-01

Full Text Available Toxoplasmosis, a zoonosis of worldwide distribution, has importance in human and veterinary medicine. Animals can be direct or indirect source of infection to man, and this intermediate host, the disease may be responsible for encephalitis and deaths due to congenital form as coinfection in neonates and patients with acquired immunodeficiency syndrome. The man and animals can acquire the disease by eating undercooked meat or cures, infected with tissue cysts, as well as food and water contaminated with oocysts. Iatrogenic, such as, blood transfusion and organ transplantation are other less frequent routes of transmission. The causative agent of this disease is Toxoplasma gondii, a protozoan obligate intracellular coccidian. In small animals, the infection has been reported in several countries, promoting varied clinical manifestations and uncommon but severe and fatal, which is a challenge in the clinical diagnosis of small animals, especially when the nervous system involvement. Thus, constitute the purpose of this review address the participation of small animals in the spread of the disease, clinical aspects related to it, as well as discuss methods of diagnosis, therapeutic measures, prophylaxis and control of this disease.

Small Animal Models for Evaluating Filovirus Countermeasures.

Science.gov (United States)

Banadyga, Logan; Wong, Gary; Qiu, Xiangguo

2018-05-11

The development of novel therapeutics and vaccines to treat or prevent disease caused by filoviruses, such as Ebola and Marburg viruses, depends on the availability of animal models that faithfully recapitulate clinical hallmarks of disease as it is observed in humans. In particular, small animal models (such as mice and guinea pigs) are historically and frequently used for the primary evaluation of antiviral countermeasures, prior to testing in nonhuman primates, which represent the gold-standard filovirus animal model. In the past several years, however, the filovirus field has witnessed the continued refinement of the mouse and guinea pig models of disease, as well as the introduction of the hamster and ferret models. We now have small animal models for most human-pathogenic filoviruses, many of which are susceptible to wild type virus and demonstrate key features of disease, including robust virus replication, coagulopathy, and immune system dysfunction. Although none of these small animal model systems perfectly recapitulates Ebola virus disease or Marburg virus disease on its own, collectively they offer a nearly complete set of tools in which to carry out the preclinical development of novel antiviral drugs.

Efficient system modeling for a small animal PET scanner with tapered DOI detectors

International Nuclear Information System (INIS)

Zhang, Mengxi; Zhou, Jian; Yang, Yongfeng; Qi, Jinyi; Rodríguez-Villafuerte, Mercedes

2016-01-01

A prototype small animal positron emission tomography (PET) scanner for mouse brain imaging has been developed at UC Davis. The new scanner uses tapered detector arrays with depth of interaction (DOI) measurement. In this paper, we present an efficient system model for the tapered PET scanner using matrix factorization and a virtual scanner geometry. The factored system matrix mainly consists of two components: a sinogram blurring matrix and a geometrical matrix. The geometric matrix is based on a virtual scanner geometry. The sinogram blurring matrix is estimated by matrix factorization. We investigate the performance of different virtual scanner geometries. Both simulation study and real data experiments are performed in the fully 3D mode to study the image quality under different system models. The results indicate that the proposed matrix factorization can maintain image quality while substantially reduce the image reconstruction time and system matrix storage cost. The proposed method can be also applied to other PET scanners with DOI measurement. (paper)

Dose evaluation of three-dimensional small animal phantom with film dosimetry

International Nuclear Information System (INIS)

Han, Su Chul; Park, Seung Woo

2017-01-01

The weight of small animal dosimetry has been continuously increased in pre-clinical studies using radiation in small animals. In this study, three-dimensional(3D) small animal phantom was fabricated using 3D printer which has been continuously used and studied in the various fields. The absorbed dose of 3D animal phantom was evaluated by film dosimetry. Previously, the response of film was obtained from the materials used for production of 3D small animal phantom and compared with the bolus used as the tissue equivalent material in the radiotherapy. When irradiated with gamma rays from 0.5 Gy to 6 Gy, it was confirmed that there was a small difference of less than 1% except 0.5 Gy dose. And when small animal phantom was irradiated with 5 Gy, the difference between the irradiated dose and calculated dose from film was within 2%. Based on this study, it would be possible to increase the reliability of dose in pre-clinical studies using irradiation in small animals by evaluating dose of 3D small animal phantom

Dose evaluation of three-dimensional small animal phantom with film dosimetry

Energy Technology Data Exchange (ETDEWEB)

Han, Su Chul [Div. of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Park, Seung Woo [Radilogcial and Medico-Oncological Sciences, University of Sciences and Technology, Daejeon (Korea, Republic of)

2017-03-15

The weight of small animal dosimetry has been continuously increased in pre-clinical studies using radiation in small animals. In this study, three-dimensional(3D) small animal phantom was fabricated using 3D printer which has been continuously used and studied in the various fields. The absorbed dose of 3D animal phantom was evaluated by film dosimetry. Previously, the response of film was obtained from the materials used for production of 3D small animal phantom and compared with the bolus used as the tissue equivalent material in the radiotherapy. When irradiated with gamma rays from 0.5 Gy to 6 Gy, it was confirmed that there was a small difference of less than 1% except 0.5 Gy dose. And when small animal phantom was irradiated with 5 Gy, the difference between the irradiated dose and calculated dose from film was within 2%. Based on this study, it would be possible to increase the reliability of dose in pre-clinical studies using irradiation in small animals by evaluating dose of 3D small animal phantom.

Positron implantation profile in kapton

International Nuclear Information System (INIS)

Plotkowski, K.; Panek, T.J.; Kansj, J.

1988-01-01

Measurements of positrons' implantation profile were made with geometry as in the majority of PAT experiments, making use of the difference in values of mean lifetimes of positrons in the absorber and in the detector. The function describing the absorption of positrons in the absorber taking into account measurement geometry was fitted to the experimental data. The correction to the exponential relation occurring in this function is the dominating factor for small thicknesses of the absorber. In this analysis various values of positrons' backscatter coefficients of the nickel and of the kapton were also taken into account

SmartPET: Applying HPGe and pulse shape analysis to small-animal PET

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool (United Kingdom)], E-mail: rjc@ns.ph.liv.ac.uk; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G. [Department of Physics, University of Liverpool (United Kingdom); Hall, C.J.; Lazarus, I. [CCLRC Daresbury Laboratory, Warrington, Cheshire (United Kingdom); Berry, A.; Beveridge, T.; Gillam, J.; Lewis, R.A. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia)

2007-08-21

The SmartPET project is the development of a prototype small-animal imaging system based on the use of Hyperpure Germanium (HPGe) detectors. The use of digital electronics and application of Pulse Shape Analysis (PSA) techniques provide fine spatial resolution, while the excellent intrinsic energy resolution of HPGe detectors makes the system ideal for multi-nuclide imaging. As a result, the SmartPET system has the potential to function as a dual modality imager, operating as a dual-head Positron Emission Tomography (PET) camera or in a Compton Camera configuration for Single Photon Emission Computed Tomography (SPECT) imaging. In this paper, we discuss how the use of simple PSA techniques greatly improves the position sensitivity of the detector yielding improved spatial resolution in reconstructed images. The PSA methods presented have been validated by comparison to data from high-precision scanning of the detectors. Results from this analysis are presented along with initial images from the SmartPET system, which demonstrates the impact of these techniques on PET images.

Cyclotrons and positron emitting radiopharmaceuticals

International Nuclear Information System (INIS)

Wolf, A.P.; Fowler, J.S.

1984-01-01

The state of the art of Positron Emission Tomography (PET) technology as related to cyclotron use and radiopharmaceutical production is reviewed. The paper discusses available small cyclotrons, the positron emitters which can be produced and the yields possible, target design, and radiopharmaceutical development and application. 97 refs., 12 tabs

Cyclotrons and positron emitting radiopharmaceuticals

Energy Technology Data Exchange (ETDEWEB)

Wolf, A.P.; Fowler, J.S.

1984-01-01

The state of the art of Positron Emission Tomography (PET) technology as related to cyclotron use and radiopharmaceutical production is reviewed. The paper discusses available small cyclotrons, the positron emitters which can be produced and the yields possible, target design, and radiopharmaceutical development and application. 97 refs., 12 tabs. (ACR)

Development of positron emitting radionuclides for imaging with improved positron detectors

International Nuclear Information System (INIS)

Yano, Y.

1976-10-01

Recent advances in positron cameras and positron ring detectors for transverse section reconstruction have created renewed interest in positron emitting radionuclides. This paper reports on: generator-produced 82 Rb; cyclotron-produced 62 Zn; and reactor-produced 64 Cu. Investigation of the 82 Sr (25 d)-- 82 Rb (75 s) generator determined the elution characteristics for Bio-Rex 70, a weakly acidic carboxylic cation exchanger, using 2% NaCl as the eluent. The yield of 82 Rb and the breakthrough of 82 Sr were determined for newly prepared columns and for long term elution conditions. Spallation-produced 82 Sr was used to charge a compact 82 Rb generator to obtain multi-millicurie amounts of 82 Rb for myocardial imaging. Zinc accumulates in the islet cells of the pancreas and in the prostate. Zinc-62 was produced by protons on Cu foil and separated by column chromatography. Zinc-62 was administered as the amino acid chelates and as the ZnCl 2 to tumor and normal animals. Tissue distribution was determined for various times after intravenous injection. Pancreas-liver images of 62 Zn-histidine uptake were obtained in animals with the gamma camera and the liver uptake of /sup 99m/Tc sulfur colloid was computer subtracted to image the pancreas alone. The positron camera imaged uptake of 62 Zn-histidine in the prostate of a dog at 20 h. 64 Cu was chelated to asparagine, a requirement of leukemic cells, and administered to lymphoma mice. Uptake in tumor and various tissues was determined and compared with the uptake of 67 Ga citrate under the same conditions. 64 Cu-asparagine had better tumor-to-soft tissue ratios than 67 Ga-citrate

Positron emission tomography

International Nuclear Information System (INIS)

Yamamoto, Y.L.; Thompson, C.J.; Diksic, M.; Meyer, E.; Feindel, W.H.

1984-01-01

One of the most exciting new technologies introduced in the last 10 yr is positron emission tomography (PET). PET provides quantitative, three-dimensional images for the study of specific biochemical and physiological processes in the human body. This approach is analogous to quantitative in-vivo autoradiography but has the added advantage of permitting non-invasive in vivo studies. PET scanning requires a small cyclotron to produce short-lived positron emitting isotopes such as oxygen-15, carbon-11, nitrogen-13 and fluorine-18. Proper radiochemical facilities and advanced computer equipment are also needed. Most important, PET requires a multidisciplinary scientific team of physicists, radiochemists, mathematicians, biochemists and physicians. The most recent trends are reviewed in the imaging technology, radiochemistry, methodology and clinical applications of positron emission tomography. (author)

Role of radiotracer in animal science

International Nuclear Information System (INIS)

Sivaprasad, N.

2015-01-01

Radiotracers have been used as radiopharmaceuticals for diagnosis and treatment of animal diseases in cattle and pet animals. In fact the veterinary nuclear medicine based on radiotracer as radiopharmaceuticals is established medical technique for functional studies and imaging of vital organs such as heart, lung, brain, spleen, liver, kidney etc for diagnosis as well as treatment of diseases such as cancers in animal. Besides, radiation from radioisotopes has been in use for radiation therapy of cancers in animals. The nuclear imaging using positron emitting radiotracer is gaining importance in the evolution of drug in small animals. In this respect, small animals have also contributed significantly in the development of radiopharmaceuticals particularly for biodistribution and bioscan studies. In fact, the quality control of radiopharmaceuticals in animals to test the safety is a mandatory requirement in the production of radiopharmaceuticals. In brief the animal science has contributed in various areas and facets of radiotracer techniques and its application vice versa the radiotracer techniques have contributed towards the progress of animal science. The animal science in combination with radiotracer has also contributed to the progress of other basic and applied sciences. Thus there exists a bond between radiotracer techniques and animal science. Some aspects of mutual dependence of animal science and radiotracer are elaborated

Intrinsic respiratory gating in small-animal CT

International Nuclear Information System (INIS)

Bartling, Soenke H.; Dinkel, Julien; Kauczor, Hans-Ulrich; Stiller, Wolfram; Semmler, Wolfhard; Grasruck, Michael; Madisch, Ijad; Gupta, Rajiv; Kiessling, Fabian

2008-01-01

Gating in small-animal CT imaging can compensate artefacts caused by physiological motion during scanning. However, all published gating approaches for small animals rely on additional hardware to derive the gating signals. In contrast, in this study a novel method of intrinsic respiratory gating of rodents was developed and tested for mice (n=5), rats (n=5) and rabbits (n=2) in a flat-panel cone-beam CT system. In a consensus read image quality was compared with that of non-gated and retrospective extrinsically gated scans performed using a pneumatic cushion. In comparison to non-gated images, image quality improved significantly using intrinsic and extrinsic gating. Delineation of diaphragm and lung structure improved in all animals. Image quality of intrinsically gated CT was judged to be equivalent to extrinsically gated ones. Additionally 4D datasets were calculated using both gating methods. Values for expiratory, inspiratory and tidal lung volumes determined with the two gating methods were comparable and correlated well with values known from the literature. We could show that intrinsic respiratory gating in rodents makes additional gating hardware and preparatory efforts superfluous. This method improves image quality and allows derivation of functional data. Therefore it bears the potential to find wide applications in small-animal CT imaging. (orig.)

Prevalence and pattern of small animal orthopaedic conditions at ...

African Journals Online (AJOL)

Small animal orthopaedic case records of a 20-year period were surveyed to obtain the prevalence and pattern of orthopaedic conditions presented to the Veterinary Teaching Hospital (VTH), University of Ibadan, Nigeria, with the objective of providing data for planning on small animal healthcare facilities, policy ...

Small amplitude Kinetic Alfven waves in a superthermal electron-positron-ion plasma

Science.gov (United States)

Adnan, Muhammad; Mahmood, Sahahzad; Qamar, Anisa; Tribeche, Mouloud

2016-11-01

We are investigating the propagating properties of coupled Kinetic Alfven-acoustic waves in a low beta plasma having superthermal electrons and positrons. Using the standard reductive perturbation method, a nonlinear Korteweg-de Vries (KdV) type equation is derived which describes the evolution of Kinetic Alfven waves. It is found that nonlinearity and Larmor radius effects can compromise and give rise to solitary structures. The parametric role of superthermality and positron content on the characteristics of solitary wave structures is also investigated. It is found that only sub-Alfvenic and compressive solitons are supported in the present model. The present study may find applications in a low β electron-positron-ion plasma having superthermal electrons and positrons.

Frequency domain fluorescence diffuse tomography of small animals

Science.gov (United States)

Orlova, Anna G.; Turchin, Ilya V.; Kamensky, Vladislav A.; Plehanov, Vladimir I.; Balalaeva, Irina V.; Sergeeva, Ekaterina A.; Shirmanova, Marina V.; Kleshnin, Michail S.

2007-05-01

Fluorescent compounds for selective cancer cell marking are used for development of novel medical diagnostic methods, investigation of the influence of external factors on tumor growth, regress and metastasis. Only special tools for turbid media imaging, such as optical diffusion tomography permit noninvasive monitoring of fluorescent-labeled tumor alterations deep in animal tissue. In this work, the results of preliminary experiments utilizing frequency-domain fluorescent diffusion tomography (FD FDT) experimental setup in small animal are presented. Low-frequency modulated light (1 kHz) from Nd:YAG laser with second harmonic generation at the wavelength of 532 nm was used in the setup. The transilluminative planar configuration was used in the setup. A series of model experiments has been conducted and show good agreement between theoretical and experimental fluorescence intensity. Models of deep tumors were created by two methods: (1) glass capsules containing fluorophore solution were inserted into esophagus of small animals to simulate marked tumors; (2) a suspension of transfected HEΚ293-Turbo-RFP cells was subcutaneously injected to small animal. The conducted experiments have shown that FD FDT allows one to detect the presence of labeled tumor cells in small animals, to determine the volume of an experimental tumor, to perform 3D tumor reconstruction, as well as to conduct monitoring investigations. The obtained results demonstrate the potential capability of the FD FDT method for noninvasive whole-body imaging in cancer studies, diagnostics and therapy.

Metabolic and hemodynamic evaluation of brain metastases from small cell lung cancer with positron emission tomography

DEFF Research Database (Denmark)

Lassen, U; Andersen, P; Daugaard, G

1998-01-01

for studies of metabolic and hemodynamic features. This study was performed to determine regional cerebral metabolic rate of glucose (rCMRglu), regional cerebral blood flow (rCBF), and regional cerebral blood volume (rCBV) in brain metastases from small cell lung cancer and the surrounding brain. Tumor r......Brain metastases from small cell lung cancer respond to chemotherapy, but response duration is short and the intracerebral concentration of chemotherapy may be too low because of the characteristics of the blood-brain barrier. Positron emission tomography has been applied in a variety of tumors...

A small animal PET based on GAPDs and charge signal transmission approach for hybrid PET-MR imaging

Energy Technology Data Exchange (ETDEWEB)

Kang, Jihoon; Choi, Yong; Hong, Key Jo; Hu, Wei; Jung, Jin Ho; Huh, Yoonsuk [Department of Electronic Engineering, Sogang University, 1 Shinsu-Dong, Mapo-Gu, Seoul 121-742 (Korea, Republic of); Kim, Byung-Tae, E-mail: ychoi.image@gmail.com [Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-Dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of)

2011-08-15

Positron emission tomography (PET) employing Geiger-mode avalanche photodiodes (GAPDs) and charge signal transmission approach was developed for small animal imaging. Animal PET contained 16 LYSO and GAPD detector modules that were arranged in a 70 mm diameter ring with an axial field of view of 13 mm. The GAPDs charge output signals were transmitted to a preamplifier located remotely using 300 cm flexible flat cables. The position decoder circuits (PDCs) were used to multiplex the PET signals from 256 to 4 channels. The outputs of the PDCs were digitized and further-processed in the data acquisition unit. The cross-compatibilities of the PET detectors and MRI were assessed outside and inside the MRI. Experimental studies of the developed full ring PET were performed to examine the spatial resolution and sensitivity. Phantom and mouse images were acquired to examine the imaging performance. The mean energy and time resolution of the PET detector were 17.6% and 1.5 ns, respectively. No obvious degradation on PET and MRI was observed during simultaneous PET-MRI data acquisition. The measured spatial resolution and sensitivity at the CFOV were 2.8 mm and 0.7%, respectively. In addition, a 3 mm diameter line source was clearly resolved in the hot-sphere phantom images. The reconstructed transaxial PET images of the mouse brain and tumor displaying the glucose metabolism patterns were imaged well. These results demonstrate GAPD and the charge signal transmission approach can allow the development of high performance small animal PET with improved MR compatibility.

Positron lifetime technique with applications in materials science

International Nuclear Information System (INIS)

Vries, J. de.

1987-01-01

This thesis deals with the positron lifetime technique as a method to measure extremely low concentrations of extremely small cavities in materials. The method is based upon the fact that the positron lieftime decreases as the electron density increases and upon the fact that a positron preferably annihilates in cavity-like defects in lattices. The theory of positron behaviour in materials and technical aspects of measuring positron liefetimes are described in ch.'s 2 and 3 respectively. Three methods for increasing the time resolution are discussed and some positron sources are described (ch.4). Some applications of the positron lifetime technique and experimental results are shown in chapter 5. 125 refs.; 61 figs.; 18 tabs

Theory, development, and applications of the scanning positron microbeam and positron reemission microscope

International Nuclear Information System (INIS)

Brandes, G.R.

1990-01-01

The theory, design, development, and applications of two new imaging instruments, the scanning positron microbeam (SPM) and positron reemission microscope (PRM), are discussed. The SPM consists of a sectored lens which focuses and rasters the positrons from the beam across the sample. The results of rastering the 10μm x 50μm beam across a test grid demonstrate the SPM's ability to scan a 500μm diameter region and to resolve features with ∼ 5μm resolution. The SPM was used to examine the location of defects in a Si-on-SiO 2 sample. Possible applications to three dimensional defect spectroscopy and the observation of small samples are considered. In the PRM, the positrons from the brightness-enhanced beam are focused at 5keV to an 8/Am diameter spot (FWHM) onto a thin metal single crystal. An image of the opposing side of the film is formed by accelerating and focusing the reemitted thermalized positrons with a cathode lens objective and a projector lens. The final image (real) is a record of the thermal positron emission intensity versus position. Images of surface and subsurface defect structures, taken at magnifications up to 4400x and with a resolution up to 80nm, are presented and discussed. The ultimate resolution capabilities and possible applications of the PRM are examined. The implantation and diffusion process of positrons was studied with the PRM by examining the positron emission profile of 3-9keV positrons implanted into a 2200 angstrom thick Ni single crystal

A new generation of PET scanners for small animal studies

International Nuclear Information System (INIS)

Hegyesi, G.; Imrek, J.; Kalinka, G.; Molnar, J.; Novak, D.; Valastyan, I.; Balkay, L.; Emri, M.; Kis, S.; Tron, L.

2008-01-01

Complete text of publication follows. Research on small animal PET scanners has been a hot topic in recent years. These devices are used in the preclinical phases of drug tests and during the development of new radiopharmaceuticals. They also provide a cost efficient way to test new materials, new design concepts and new technologies that later can be used to build more efficient human medical imaging devices. The development of a PET scanner requires expertise on different fields, therefore a consortium was formed that brought together Hungarian academic and industrial partners: the Nuclear Research Institute (which has experience in the development of nuclear detectors and data acquisition systems), the PET Center of the University of Debrecen (which has clinical experience in the application of nuclear imaging devices and background in image processing software), Mediso Ltd. (which has been developing, manufacturing, selling and servicing medical imaging devices since 1990) and other academic partners. This consortium has been working together since 2003: the knowledge base acquired during the development of our small animal PET scanners (miniPET-I and miniPET-II) is now being utilized to build a commercial multimodal human PET scanner. The operation of a PET scanner is based on the simultaneous detection ('coincidence') of two gamma photons originating from a positron annihilation. In traditional PET scanners coincidence is detected by a central unit during the measurement. In our system there is no such central module: all detected single gamma events are recorded (list mode data acquisition), and the list of events are processed using a computer cluster (built from PCs). The usage of independent detector modules and commercial components reduce both development and maintenance costs. Also, this mode of data acquisition is more suitable for development purposes, since once the data is collected and stored it can be used many times to test different signal

A simulation study of a method to reduce positron annihilation spread distributions using a strong magnetic field in positron emission tomography

International Nuclear Information System (INIS)

Iida, H.; Kanno, I.; Miura, S.; Murakami, M.; Takahashi, V.; Kemura, K.

1986-01-01

The positron trajectories have been three-dimensionally simulated using a Monte-Carlo method under various strength of the magnetic field. More than 5 tesla of the field confined the positrons effectively, resulting in increase of the probability of the annihilation within a limited small region, hence the higher spatial resolution in positron emission tomography

Production of slow positron beam with small diameter using electron linac in Osaka University

Energy Technology Data Exchange (ETDEWEB)

Honda, Yoshihide; Sawada, Junichi; Yamada, Masaki; Maekawa, Masaki; Okuda, Shuichi; Yoshida, Yoichi; Isoyama, Goro; Tagawa, Seiichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Yamamoto, Takayoshi

1997-03-01

A slow positron facility using an electron linac was designed and constructed. The specifications were mainly decided by numerical calculations. The slow positrons are transported along magnetic field line. The cross sectional size of slow positron beam is 1-2cm and the maximum conversion rate from electron to positron is about 1.5 x 10{sup -6}. This value is about 1/4 of ideal case in our system. Extraction of slow positron beam from magnetic field region was made and preliminary brightness enhancement experiment was also performed. (author)

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

Science.gov (United States)

Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S.; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

2015-01-01

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm2 and the total size of the detector head is 47.8 × 46.3 mm2. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

International Nuclear Information System (INIS)

Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S.; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

2015-01-01

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm 2 and the total size of the detector head is 47.8 × 46.3 mm 2 . Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can

High-resolution tomography of positron emitters with clustered pinhole SPECT

Energy Technology Data Exchange (ETDEWEB)

Goorden, Marlies C; Beekman, Freek J [Section of Radiation Detection and Medical Imaging, Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)], E-mail: m.c.goorden@tudelft.nl

2010-03-07

State-of-the-art small-animal single photon emission computed tomography (SPECT) enables sub-half-mm resolution imaging of radio-labelled molecules. Due to severe photon penetration through pinhole edges, current multi-pinhole SPECT is not suitable for high-resolution imaging of photons with high energies, such as the annihilation photons emitted by positron emitting tracers (511 keV). To deal with this edge penetration, we introduce here clustered multi-pinhole SPECT (CMP): each pinhole in a cluster has a narrow opening angle to reduce photon penetration. Using simulations, CMP is compared with (i) a collimator with traditional pinholes that is currently used for sub-half-mm imaging of SPECT isotopes (U-SPECT-II), and (ii), like (i) but with collimator thickness adapted to image high-energy photons (traditional multi-pinhole SPECT, TMP). At 511 keV, U-SPECT-II is able to resolve the 0.9 mm rods of an iteratively reconstructed Jaszczak-like capillary hot rod phantom, and while TMP only leads to small improvements, CMP can resolve rods as small as 0.7 mm. Using a digital tumour phantom, we show that CMP resolves many details not assessable with standard USPECT-II and TMP collimators. Furthermore, CMP makes it possible to visualize uptake of positron emitting tracers in sub-compartments of a digital mouse striatal brain phantom. This may open up unique possibilities for analysing processes such as those underlying the function of neurotransmitter systems. Additional potential of CMP may include (i) the imaging of other high-energy single-photon emitters (e.g. I-131) and (ii) localized imaging of positron emitting tracers simultaneously with single photon emitters, with an even better resolution than coincidence PET.

Development of small-diameter lead-glass-tube matrices for gamma-ray conversion in positron emission tomography

International Nuclear Information System (INIS)

Schwartz, G.M.

1985-05-01

A gamma-ray converter for a multiwire proportional chamber (MWPC) positron emission tomograph is described. The converter is made of small-diameter (0.48 mm inner diameter, 0.06 mm wall thickness) lead-oxide-glass tubes fused to form a honeycomb matrix. The surfaces of the tubes are reduced in a hydrogen atmosphere to provide the drift electric field for detection of the conversion electrons. The detection efficiency for a 10 mm thick converter is 6.65%, with a time resolution of 160 ns (FWHM). A scheme which will improve the spatial resolution of the tomograph by use of the self quenching streamer mode of chamber operation is described. Details of construction of the converters and the MWPC are presented, as well as the design performance of a high spatial resolution positron emission tomograph (HISPET). 40 refs., 22 figs

Small animal SPECT and its place in the matrix of molecular imaging technologies

International Nuclear Information System (INIS)

Meikle, Steven R; Kench, Peter; Kassiou, Michael; Banati, Richard B

2005-01-01

Molecular imaging refers to the use of non-invasive imaging techniques to detect signals that originate from molecules, often in the form of an injected tracer, and observe their interaction with a specific cellular target in vivo. Differences in the underlying physical principles of these measurement techniques determine the sensitivity, specificity and length of possible observation of the signal, characteristics that have to be traded off according to the biological question under study. Here, we describe the specific characteristics of single photon emission computed tomography (SPECT) relative to other molecular imaging technologies. SPECT is based on the tracer principle and external radiation detection. It is capable of measuring the biodistribution of minute ( -10 molar) concentrations of radio-labelled biomolecules in vivo with sub-millimetre resolution and quantifying the molecular kinetic processes in which they participate. Like some other imaging techniques, SPECT was originally developed for human use and was subsequently adapted for imaging small laboratory animals at high spatial resolution for basic and translational research. Its unique capabilities include (i) the ability to image endogenous ligands such as peptides and antibodies due to the relative ease of labelling these molecules with technetium or iodine (ii) the ability to measure relatively slow kinetic processes (compared with positron emission tomography, for example) due to the long half-life of the commonly used isotopes and (iii) the ability to probe two or more molecular pathways simultaneously by detecting isotopes with different emission energies. In this paper, we review the technology developments and design tradeoffs that led to the current state-of-the-art in SPECT small animal scanning and describe the position SPECT occupies within the matrix of molecular imaging technologies. (topical review)

Production and applications of positron microbeams

International Nuclear Information System (INIS)

Brandes, G.R.; Canter, K.F.; Horsky, T.N.; Lippel, P.H.; Mills, A.P. Jr.

1989-01-01

The production of a positron microbeam using the high-brightness beam developed at Brandeis University and possible applications of this microbeam to spatially resolved defect studies and positron microscopy are reviewed. The high-brightness beam consists of a W(110) primary moderator and two remoderation stages which provide a 500-fold increase in brightness. With this brightness increase and microbeam optics, we are able to form a 12 μm FWHM beam (48 mrad pencil half-angle) at 5 keV beam energy. The well characterised small-diameter beam is particularly adaptable for determining defect concentration and structure, both laterally and in a depth-profiling mode. In the case of a transmission positron microscope or a positron re-emission microscope operating in a high-magnification mode, efficient image formation requires the use of a microbeam to maximise the number of positrons in the area being imaged. Results of the scanning microbeam tests and the application of a microbeam to positron microscopy and defect studies are reviewed. (author)

Design of a superconducting accelerator for positron annihilation spectroscopy

International Nuclear Information System (INIS)

Oshima, Nagayasu; Kuroda, Ryunosuke; Suzuki, Ryoichi; Kinomura, Atsushi; Ohdaira, Toshiyuki; Hayashizaki, Noriyosu; Hattori, Toshiyuki

2008-01-01

A design of a superconducting accelerator for a positron beam with energy of ∼1 MeV for positron annihilation spectroscopy is proposed. The total system can be extremely small with an application of superconducting technology. Both a miniaturization and easy maintenance of the accelerator can be achieved by usage of a small liquidless refrigerator for cooling of a superconducting RF cavity. Moreover, operation duty cycle of the superconducting cavity is ∼100%. The required RF power to drive the system is only ∼10 W, therefore a large-size klystron is not necessary. The designed system including a slow positron source is small (∼2 m 3 ) enough to be used in a general laboratory. (author)

Estimation of organ motion for gated PET imaging in small animal using artificial tumor

Energy Technology Data Exchange (ETDEWEB)

Woo, Sang Keun; Yu, Jung Woo; Lee, Yong Jin [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2011-10-15

The image quality is lowered by reducing of contrast and signal due to breathing and heart motion when acquire Positron Emission Tomography (PET) image of small animal tumor. Therefore motion correction is required for betterment of quantitative estimation of tumor. The gated PET using external monitoring device is commonly used for motion correction. But that method has limitation by reason of detection from the outside. Therefore, we had devised the in-vivo motion assessment. In-vivo motion has been demonstrated in lung, liver and abdomen region of rats by coated molecular sieve. In PET image analysis, count and SNR were drawn in the target region. The motion compensation PET image for optimal gate number was confirmed by FWHM. Artificial motion evaluation of tumor using molecular sieve suggests possibility of motion correction modeling without external monitoring devices because it estimates real internal motion of lung, liver, and abdomen. The purpose of this study was to assess the optimal gates number for each region and to improve quantitative estimation of tumor

Evaluation of New Inorganic Scintillators for Application in a Prototype Small Animal PET Scanner

CERN Document Server

Kuntner, C

2003-01-01

In the study of new pharmaceuticals as well as brain and genetic research, Positron Emission Tomography (PET) is a useful method. It has also recently entered the clinical domain in cardiology and particularly in oncology. Small animals such as mice, are often used to validate sophisticated models of human disease. High spatial resolution PET instrumentation is therefore necessary due to the reduced dimensions of the organs. Inorganic scintillators are employed in most of the diagnostic imaging devices. The ultimate performance of the PET scanner is tightly bound to the scintillation properties of the crystals. In the last years there has been an effort to develop new scintillating materials characterized by high light output, high detection efficiency and fast decay time. The most studied systems are mainly Ce3+-doped crystals such as LSO:Ce, YAP:Ce, LuAP:Ce, and recently also mixed Lux(RE3+)1-xAlO3:Ce crystals. These crystals are very attractive for medical application because of their high density (with th...

Semiautomated analysis of small-animal PET data.

Science.gov (United States)

Kesner, Adam L; Dahlbom, Magnus; Huang, Sung-Cheng; Hsueh, Wei-Ann; Pio, Betty S; Czernin, Johannes; Kreissl, Michael; Wu, Hsiao-Ming; Silverman, Daniel H S

2006-07-01

The objective of the work reported here was to develop and test automated methods to calculate biodistribution of PET tracers using small-animal PET images. After developing software that uses visually distinguishable organs and other landmarks on a scan to semiautomatically coregister a digital mouse phantom with a small-animal PET scan, we elastically transformed the phantom to conform to those landmarks in 9 simulated scans and in 18 actual PET scans acquired of 9 mice. Tracer concentrations were automatically calculated in 22 regions of interest (ROIs) reflecting the whole body and 21 individual organs. To assess the accuracy of this approach, we compared the software-measured activities in the ROIs of simulated PET scans with the known activities, and we compared the software-measured activities in the ROIs of real PET scans both with manually established ROI activities in original scan data and with actual radioactivity content in immediately harvested tissues of imaged animals. PET/atlas coregistrations were successfully generated with minimal end-user input, allowing rapid quantification of 22 separate tissue ROIs. The simulated scan analysis found the method to be robust with respect to the overall size and shape of individual animal scans, with average activity values for all organs tested falling within the range of 98% +/- 3% of the organ activity measured in the unstretched phantom scan. Standardized uptake values (SUVs) measured from actual PET scans using this semiautomated method correlated reasonably well with radioactivity content measured in harvested organs (median r = 0.94) and compared favorably with conventional SUV correlations with harvested organ data (median r = 0.825). A semiautomated analytic approach involving coregistration of scan-derived images with atlas-type images can be used in small-animal whole-body radiotracer studies to estimate radioactivity concentrations in organs. This approach is rapid and less labor intensive than are

State-of-the-art of small animal imaging with high-resolution SPECT

International Nuclear Information System (INIS)

Nikolaus, S.; Wirrwar, A.; Antke, C.; Kley, K.; Mueller, H.W.

2005-01-01

During the recent years, in vivo imaging of small animals using SPECT has become of growing relevance. Along with the development of dedicated high-resolution small animal SPECT cameras, an increasing number of conventional clinical scanners has been equipped with single or multipinhole collimators. This paper reviews the small animal tomographs, which are operating at present and compares their performance characteristics. Furthermore, we describe the in vivo imaging studies, which have been performed so far with the individual scanners and survey current approaches to optimize molecular imaging with small animal SPECT. (orig.)

Evaluation of nigrostriatal damage and its change over weeks in a rat model of Parkinson's disease: small animal positron emission tomography studies with [11C]β-CFT

International Nuclear Information System (INIS)

Liu Limin; Wang Yong; Li Bo; Jia Jun; Sun Zuoli; Zhang Jinming; Tian Jiahe; Wang Xiaomin

2009-01-01

Introduction: The cardinal pathological feature of Parkinson's disease (PD) is progressive loss of dopaminergic neurons. Since dopamine transporter (DAT) is a protein located presynaptically on dopaminergic nerve terminals, radioligands that bind to these sites are promising radiopharmaceuticals for evaluation of the integrity of the dopamine system. This study using positron emission tomography (PET) tracers, [ 11 C]-2β-carbomethoxy-3β-(4-fluorophenyl)-tropane ([ 11 C]β-CFT, radioligand for DAT), was aimed at evaluating the degree of nigrostriatal damage and its change over weeks in a rat model of PD. Methods: The brains of these rats were unilaterally lesioned by mechanical transection of the nigrostriatal dopamine pathway at the medial forebrain bundle (MFB). Behavioral studies were carried out by apomorphine (APO) challenge prior to and 1, 2 and 4 weeks after MFB axotomy. Small animal PET scans were performed 2 days after the behavioral test. Immunohistochemistry was conducted 4 days after the last PET scan. Results: Compared with the contralateral intact side, a progressively decreased [ 11 C]β-CFT binding was observed on the lesioned side which correlated inversely with the APO-induced rotations. Postmortem immunohistochemical studies confirmed the loss of both striatal dopamine fibers and nigral neurons on the lesioned side. Conclusion: These findings not only demonstrate that the neuronal degeneration in this model is relatively slow, but also suggest [ 11 C]β-CFT is a sensitive marker to monitor the degree of nigrostriatal damage and its change over weeks. This marker can be used prospectively to study the progression of the disease, thereby making detection of early phases of PD possible.

Assessing Glomerular Filtration in Small Animals Using [68Ga]DTPA and [68Ga]EDTA with PET Imaging.

Science.gov (United States)

Gündel, Daniel; Pohle, Ulrike; Prell, Erik; Odparlik, Andreas; Thews, Oliver

2018-06-01

Determining the glomerular filtration rate (GFR) is essential for clinical medicine but also for pre-clinical animal studies. Functional imaging using positron emission tomography (PET) allows repetitive almost non-invasive measurements. The aim of the study was the development and evaluation of easily synthesizable PET tracers for GFR measurements in small animals. Diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) were labeled with Ga-68. The binding to blood cells and plasma proteins was tested in vitro. The distribution of the tracers in rats was analyzed by PET imaging and ex vivo measurements. From the time-activity-curve of the blood compartment (heart) and the total tracer mass excreted by the kidney, the GFR was calculated. These values were compared directly with the inulin clearance in the same animals. Both tracers did not bind to blood cells. [ 68 Ga]DPTA but not [ 68 Ga]EDTA showed strong binding to plasma proteins. For this reason, [ 68 Ga]DPTA stayed much longer in the blood and only 30 % of the injected dose was eliminated by the kidney within 60 min whereas the excretion of [ 68 Ga]EDTA was 89 ± 1 %. The calculated GFR using [ 68 Ga]EDTA was comparable to the measured inulin clearance in the same animal. Using [ 68 Ga]-DPTA, the measurements led to values which were 80 % below the normal GFR. The results also revealed that definition of the volume of interest for the blood compartment affects the calculation and may lead to a slight overestimation of the GFR. [ 68 Ga]EDTA is a suitable tracer for GFR calculation from PET imaging in small animals. It is easy to be labeled, and the results are in good accordance with the inulin clearance. [ 68 Ga]DTPA led to a marked underestimation of GFR due to its strong binding to plasma proteins and is therefore not an appropriate tracer for GFR measurements.

Positron range in tissue-equivalent materials: experimental microPET studies

Science.gov (United States)

Alva-Sánchez, H.; Quintana-Bautista, C.; Martínez-Dávalos, A.; Ávila-Rodríguez, M. A.; Rodríguez-Villafuerte, M.

2016-09-01

In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with 18F, 13N or 68Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

Ultrarelativistic electron and positron radiation in planar channeling

International Nuclear Information System (INIS)

Kalashnikov, N.P.; Olchack, A.S.

1980-01-01

The coherent electromagnetic radiation from channeling electrons and positrons is given by similar expression. However for the channeling positrons the close collisions are suppressed due to the fact that the positron wave function is exponentially small near the atoms of the crystal lattice. It follows that the coherent bremsstrahlung decreases for the channeling positrons. We have investigated the ultrarelativistic channeling electron and positron radiations, connected with the electromagnetic transitions from the continuum spectrum states to the quasi-bound spectrum states and between the different quasi-bound spectrum states. The radiation probabilities are calculated by using the model continuum planar potential. It is shown that the radiation from the channeling electrons is several orders of magnitude larger than the positron radiation, while the electron and positron radiation have similar characteristics such as frequency limitation and angular distribution of the radiation. (orig.)

Positron range in PET imaging: an alternative approach for assessing and correcting the blurring

Science.gov (United States)

Jødal, L.; Le Loirec, C.; Champion, C.

2012-06-01

Positron range impairs resolution in PET imaging, especially for high-energy emitters and for small-animal PET. De-blurring in image reconstruction is possible if the blurring distribution is known. Furthermore, the percentage of annihilation events within a given distance from the point of positron emission is relevant for assessing statistical noise. This paper aims to determine the positron range distribution relevant for blurring for seven medically relevant PET isotopes, 18F, 11C, 13N, 15O, 68Ga, 62Cu and 82Rb, and derive empirical formulas for the distributions. This paper focuses on allowed-decay isotopes. It is argued that blurring at the detection level should not be described by the positron range r, but instead the 2D projected distance δ (equal to the closest distance between decay and line of response). To determine these 2D distributions, results from a dedicated positron track-structure Monte Carlo code, Electron and POsitron TRANsport (EPOTRAN), were used. Materials other than water were studied with PENELOPE. The radial cumulative probability distribution G2D(δ) and the radial probability density distribution g2D(δ) were determined. G2D(δ) could be approximated by the empirical function 1 - exp(-Aδ2 - Bδ), where A = 0.0266 (Emean)-1.716 and B = 0.1119 (Emean)-1.934, with Emean being the mean positron energy in MeV and δ in mm. The radial density distribution g2D(δ) could be approximated by differentiation of G2D(δ). Distributions in other media were very similar to water. The positron range is important for improved resolution in PET imaging. Relevant distributions for the positron range have been derived for seven isotopes. Distributions for other allowed-decay isotopes may be estimated with the above formulas.

Optimization and performance evaluation of the microPET II scanner for in vivo small-animal imaging

International Nuclear Information System (INIS)

Yang Yongfeng; Tai Yuanchuan; Siegel, Stefan; Newport, Danny F; Bai, Bing; Li, Quanzheng; Leahy, Richard M; Cherry, Simon R

2004-01-01

MicroPET II is a newly developed PET (positron emission tomography) scanner designed for high-resolution imaging of small animals. It consists of 17 640 LSO crystals each measuring 0.975 x 0.975 x 12.5 mm 3 , which are arranged in 42 contiguous rings, with 420 crystals per ring. The scanner has an axial field of view (FOV) of 4.9 cm and a transaxial FOV of 8.5 cm. The purpose of this study was to carefully evaluate the performance of the system and to optimize settings for in vivo mouse and rat imaging studies. The volumetric image resolution was found to depend strongly on the reconstruction algorithm employed and averaged 1.1 mm (1.4 μl) across the central 3 cm of the transaxial FOV when using a statistical reconstruction algorithm with accurate system modelling. The sensitivity, scatter fraction and noise-equivalent count (NEC) rate for mouse- and rat-sized phantoms were measured for different energy and timing windows. Mouse imaging was optimized with a wide open energy window (150-750 keV) and a 10 ns timing window, leading to a sensitivity of 3.3% at the centre of the FOV and a peak NEC rate of 235 000 cps for a total activity of 80 MBq (2.2 mCi) in the phantom. Rat imaging, due to the higher scatter fraction, and the activity that lies outside of the field of view, achieved a maximum NEC rate of 24 600 cps for a total activity of 80 MBq (2.2 mCi) in the phantom, with an energy window of 250-750 keV and a 6 ns timing window. The sensitivity at the centre of the FOV for these settings is 2.1%. This work demonstrates that different scanner settings are necessary to optimize the NEC count rate for different-sized animals and different injected doses. Finally, phantom and in vivo animal studies are presented to demonstrate the capabilities of microPET II for small-animal imaging studies

Theoretical considerations on maximum running speeds for large and small animals.

Science.gov (United States)

Fuentes, Mauricio A

2016-02-07

Mechanical equations for fast running speeds are presented and analyzed. One of the equations and its associated model predict that animals tend to experience larger mechanical stresses in their limbs (muscles, tendons and bones) as a result of larger stride lengths, suggesting a structural restriction entailing the existence of an absolute maximum possible stride length. The consequence for big animals is that an increasingly larger body mass implies decreasing maximal speeds, given that the stride frequency generally decreases for increasingly larger animals. Another restriction, acting on small animals, is discussed only in preliminary terms, but it seems safe to assume from previous studies that for a given range of body masses of small animals, those which are bigger are faster. The difference between speed scaling trends for large and small animals implies the existence of a range of intermediate body masses corresponding to the fastest animals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tomographic evaluation of a dual-head positron emission tomography system

International Nuclear Information System (INIS)

Efthimiou, N; Maistros, S; Tripolitis, X; Panayiotakis, G; Samartzis, A; Loudos, G

2011-01-01

In this paper we present the performance evaluation results, in the planar and tomographic modes, of a low-cost positron emission tomography camera dedicated to small-animal imaging. The system consists of two pixelated Lu 2 SiO 5 crystals, two Hamamatsu H8500 position sensitive photomultiplier tubes, fast amplification electronics and an FPGA-USB-based read-out system. The parameters that have been studied are (i) saturation as a function of the head distance and photon acceptance angle, (ii) effect of the number of projections and half or complete head's rotation, (iii) spatial resolution as a function of the head distance, (iv) spatial resolution as a function of acceptance angle, (v) system's sensitivity as a function of these parameters and (vi) performance in small mice imaging. Image reconstruction has been carried out using open source software developed by our group (QSPECT), which is designed mainly for SPECT imaging. The results indicate that the system has a linear response for activities up to at least 2 MBq, which are typical in small-animal imaging. Best tomographic spatial resolution was measured to be ∼2 mm. The system has been found suitable for imaging of small mice both in the planar and tomographic modes

Treatment planning for a small animal using Monte Carlo simulation

International Nuclear Information System (INIS)

Chow, James C. L.; Leung, Michael K. K.

2007-01-01

The development of a small animal model for radiotherapy research requires a complete setup of customized imaging equipment, irradiators, and planning software that matches the sizes of the subjects. The purpose of this study is to develop and demonstrate the use of a flexible in-house research environment for treatment planning on small animals. The software package, called DOSCTP, provides a user-friendly platform for DICOM computed tomography-based Monte Carlo dose calculation using the EGSnrcMP-based DOSXYZnrc code. Validation of the treatment planning was performed by comparing the dose distributions for simple photon beam geometries calculated through the Pinnacle3 treatment planning system and measurements. A treatment plan for a mouse based on a CT image set by a 360-deg photon arc is demonstrated. It is shown that it is possible to create 3D conformal treatment plans for small animals with consideration of inhomogeneities using small photon beam field sizes in the diameter range of 0.5-5 cm, with conformal dose covering the target volume while sparing the surrounding critical tissue. It is also found that Monte Carlo simulation is suitable to carry out treatment planning dose calculation for small animal anatomy with voxel size about one order of magnitude smaller than that of the human

Advances in endoscopic surgery for small animal reproduction.

Science.gov (United States)

Katic, N; Dupré, G

2016-09-01

Although endoscopic surgery entered its "golden era" in the mid-1980s, it is still advancing at a tremendous pace. Novel surgical techniques and devices are continuously developed and applied, and new indications (and/or contraindications) for the use of endoscopic surgery are routinely reported in the literature and subjected to systematic assessments. Although endoscopic surgery (laparoscopy in particular) has already become established as the gold standard in human medicine, it has yet to be proven as a viable alternative to open surgery in the field of veterinary medicine. The advantages of minimally invasive surgery include better intra-operative visualization, reduced postoperative pain, reduced scar formation and increased postoperative mobility. Therefore, it is reasonable to expect that the application of this will continue to expand. Small animal reproduction, a field within the broad discipline of veterinary medicine, has already recognized and begun to reap the benefits of endoscopic surgery. Herein, we retrospectively review the most recent successful novel applications of endoscopic surgery in the small animal reproduction system to provide small animal reproductive surgeons with important knowledge to help improve their own veterinarian medical practice. © 2016 Blackwell Verlag GmbH.

Antimicrobial stewardship in small animal veterinary practice

DEFF Research Database (Denmark)

Guardabassi, Luca; Prescott, John F

2015-01-01

Despite the increasing recognition of the critical role for antimicrobial stewardship in preventing the spread of multidrug-resistant bacteria, examples of effective antimicrobial stewardship programs are rare in small animal veterinary practice. This article highlights the basic requirements...

Modality comparison for small animal radiotherapy: A simulation study

Energy Technology Data Exchange (ETDEWEB)

Bazalova, Magdalena, E-mail: bazalova@stanford.edu; Nelson, Geoff; Noll, John M.; Graves, Edward E. [Department of Radiation Oncology, Molecular Imaging Program at Stanford, Stanford University, Stanford, California 94305 (United States)

2014-01-15

Purpose: Small animal radiation therapy has advanced significantly in recent years. Whereas in the past dose was delivered using a single beam and a lead shield for sparing of healthy tissue, conformal doses can be now delivered using more complex dedicated small animal radiotherapy systems with image guidance. The goal of this paper is to investigate dose distributions for three small animal radiation treatment modalities. Methods: This paper presents a comparison of dose distributions generated by the three approaches—a single-field irradiator with a 200 kV beam and no image guidance, a small animal image-guided conformal system based on a modified microCT scanner with a 120 kV beam developed at Stanford University, and a dedicated conformal system, SARRP, using a 220 kV beam developed at Johns Hopkins University. The authors present a comparison of treatment plans for the three modalities using two cases: a mouse with a subcutaneous tumor and a mouse with a spontaneous lung tumor. A 5 Gy target dose was calculated using the EGSnrc Monte Carlo codes. Results: All treatment modalities generated similar dose distributions for the subcutaneous tumor case, with the highest mean dose to the ipsilateral lung and bones in the single-field plan (0.4 and 0.4 Gy) compared to the microCT (0.1 and 0.2 Gy) and SARRP (0.1 and 0.3 Gy) plans. The lung case demonstrated that due to the nine-beam arrangements in the conformal plans, the mean doses to the ipsilateral lung, spinal cord, and bones were significantly lower in the microCT plan (2.0, 0.4, and 1.9 Gy) and the SARRP plan (1.5, 0.5, and 1.8 Gy) than in single-field irradiator plan (4.5, 3.8, and 3.3 Gy). Similarly, the mean doses to the contralateral lung and the heart were lowest in the microCT plan (1.5 and 2.0 Gy), followed by the SARRP plan (1.7 and 2.2 Gy), and they were highest in the single-field plan (2.5 and 2.4 Gy). For both cases, dose uniformity was greatest in the single-field irradiator plan followed by

Positron annihilation study in La2CuO4

International Nuclear Information System (INIS)

Kubo, Y.; Asano, S.

1992-01-01

The positron annihilation study for La 2 CuO 4 are performed using the full-potential linearized augmented-plane-wave(FLAPW) calculated electron and positron densities. The electron-positron momentum density(EPMD) is computed, and the well known Lock-Crisp-West(LCW) zone folding of the EPMD is produced. In the LCW analysis, small residual variations of order about 3 % are observed. The calculations show that the relative weights of the Fermi surface discontinuities are substantially altered due to the positron preferentially sampling the Cu-O plane region

On the surveillance for animal diseases in small herds

DEFF Research Database (Denmark)

Greiner, Matthias; Dekker, Aldo

2005-01-01

Small herds may present a problem in surveillance for infectious animal diseases because typical levels of a within-herd design prevalence are not directly applicable. We suggest a definition of small herds as those smaller than 2/(within-herd design prevalence) on the basis that such herds would...... be expected to have less than two (i.e. only one) infected animals. Consequently, the probability of detecting small herds cannot be improved by choosing a larger sample size within the herd. We derive necessary sample sizes of herds and the probability ("confidence") of detecting disease within a stratum...... conservative (lower) estimates of the confidence for a given sample size and should therefore be preferred....

Small animal MRI: clinical MRI as an interface to basic biomedical research

International Nuclear Information System (INIS)

Pinkernelle, J.G.; Stelter, L.; Hamm, B.; Teichgraeber, U.

2008-01-01

The demand for highly resolved small animal MRI for the purpose of biomedical research has increased constantly. Dedicated small animal MRI scanners working at ultra high field strengths from 4.7 to 7.0 T and even above are MRI at its best. However, using high resolution RF coils in clinical scanners up to 3.0 T, small animal MRI can achieve highly resolved images showing excellent tissue contrast. In fact, in abundant experimental studies, clinical MRI is used for small animal imaging. Mostly clinical RF coils in the single-loop design are applied. In addition, custom-built RF coils and even gradient inserts are used in a clinical scanner. For the reduction of moving artifacts, special MRI-compatible animal ECG und respiration devices are available. In conclusion, clinical devices offer broad availability, are less expense in combination with good imaging performance and provide a translational nature of imaging results. (orig.)

Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

International Nuclear Information System (INIS)

Frohwein, Lynn J.; Schäfers, Klaus P.; Hoerr, Verena; Faber, Cornelius

2015-01-01

Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

Energy Technology Data Exchange (ETDEWEB)

Frohwein, Lynn J., E-mail: frohwein@uni-muenster.de; Schäfers, Klaus P. [European Institute for Molecular Imaging, University of Münster, Münster 48149 (Germany); Hoerr, Verena; Faber, Cornelius [Department of Clinical Radiology, University Hospital of Münster, Münster 48149 (Germany)

2015-07-15

Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

Positron Emission Tomography/Computed Tomography-Guided Intensity-Modulated Radiotherapy for Limited-Stage Small-Cell Lung Cancer

International Nuclear Information System (INIS)

Shirvani, Shervin M.; Komaki, Ritsuko; Heymach, John V.; Fossella, Frank V.; Chang, Joe Y.

2012-01-01

Purpose: Omitting elective nodal irradiation from planning target volumes does not compromise outcomes in patients with non–small-cell lung cancer, but whether the same is true for those with limited-stage small-cell lung cancer (LS-SCLC) is unknown. Therefore, in the present study, we sought to determine the clinical outcomes and the frequency of elective nodal failure in patients with LS-SCLC staged using positron emission tomography/computed tomography and treated with involved-field intensity-modulated radiotherapy. Methods and Materials: Between 2005 and 2008, 60 patients with LS-SCLC at our institution underwent disease staging using positron emission tomography/computed tomography before treatment using an intensity-modulated radiotherapy plan in which elective nodal irradiation was intentionally omitted from the planning target volume (mode and median dose, 45 Gy in 30 fractions; range, 40.5 Gy in 27 fractions to 63.8 Gy in 35 fractions). In most cases, concurrent platinum-based chemotherapy was administered. We retrospectively reviewed the clinical outcomes to determine the overall survival, relapse-free survival, and failure patterns. Elective nodal failure was defined as recurrence in initially uninvolved hilar, mediastinal, or supraclavicular nodes. Survival was assessed using the Kaplan-Meier method. Results: The median age of the study patients at diagnosis was 63 years (range, 39–86). The median follow-up duration was 21 months (range, 4–58) in all patients and 26 months (range, 4–58) in the survivors. The 2-year actuarial overall survival and relapse-free survival rate were 58% and 43%, respectively. Of the 30 patients with recurrence, 23 had metastatic disease and 7 had locoregional failure. We observed only one isolated elective nodal failure. Conclusions: To our knowledge, this is the first study to examine the outcomes in patients with LS-SCLC staged with positron emission tomography/computed tomography and treated with definitive

Positron Emission Tomography/Computed Tomography-Guided Intensity-Modulated Radiotherapy for Limited-Stage Small-Cell Lung Cancer

Energy Technology Data Exchange (ETDEWEB)

Shirvani, Shervin M.; Komaki, Ritsuko [Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Heymach, John V.; Fossella, Frank V. [Department of Thoracic/Head and Neck Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Chang, Joe Y., E-mail: jychang@mdanderson.org [Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States)

2012-01-01

Purpose: Omitting elective nodal irradiation from planning target volumes does not compromise outcomes in patients with non-small-cell lung cancer, but whether the same is true for those with limited-stage small-cell lung cancer (LS-SCLC) is unknown. Therefore, in the present study, we sought to determine the clinical outcomes and the frequency of elective nodal failure in patients with LS-SCLC staged using positron emission tomography/computed tomography and treated with involved-field intensity-modulated radiotherapy. Methods and Materials: Between 2005 and 2008, 60 patients with LS-SCLC at our institution underwent disease staging using positron emission tomography/computed tomography before treatment using an intensity-modulated radiotherapy plan in which elective nodal irradiation was intentionally omitted from the planning target volume (mode and median dose, 45 Gy in 30 fractions; range, 40.5 Gy in 27 fractions to 63.8 Gy in 35 fractions). In most cases, concurrent platinum-based chemotherapy was administered. We retrospectively reviewed the clinical outcomes to determine the overall survival, relapse-free survival, and failure patterns. Elective nodal failure was defined as recurrence in initially uninvolved hilar, mediastinal, or supraclavicular nodes. Survival was assessed using the Kaplan-Meier method. Results: The median age of the study patients at diagnosis was 63 years (range, 39-86). The median follow-up duration was 21 months (range, 4-58) in all patients and 26 months (range, 4-58) in the survivors. The 2-year actuarial overall survival and relapse-free survival rate were 58% and 43%, respectively. Of the 30 patients with recurrence, 23 had metastatic disease and 7 had locoregional failure. We observed only one isolated elective nodal failure. Conclusions: To our knowledge, this is the first study to examine the outcomes in patients with LS-SCLC staged with positron emission tomography/computed tomography and treated with definitive intensity

Channeling crystals for positron production

International Nuclear Information System (INIS)

Decker, F.J.

1991-05-01

Particles traversing at small angles along a single crystal axis experience a collective scattering force of many crystal atoms. The enormous fields can trap the particles along an axis or plane, called channeling. High energy electrons are attracted by the positive nuclei and therefore produce strongly enhanced so called coherent bremsstrahlung and pair production. These effects could be used in a positron production target: A single tungsten crystal is oriented to the incident electron beam within 1 mrad. At 28 GeV/c the effective radiation length is with 0.9 mm about one quarter of the amorphous material. So the target length can be shorter, which yields a higher conversion coefficient and a lower emittance of the positron beam. This makes single crystals very interesting for positron production targets. 18 refs., 2 figs

Evaluation of attenuation and scatter correction requirements in small animal PET and SPECT imaging

Science.gov (United States)

Konik, Arda Bekir

Positron emission tomography (PET) and single photon emission tomography (SPECT) are two nuclear emission-imaging modalities that rely on the detection of high-energy photons emitted from radiotracers administered to the subject. The majority of these photons are attenuated (absorbed or scattered) in the body, resulting in count losses or deviations from true detection, which in turn degrades the accuracy of images. In clinical emission tomography, sophisticated correction methods are often required employing additional x-ray CT or radionuclide transmission scans. Having proven their potential in both clinical and research areas, both PET and SPECT are being adapted for small animal imaging. However, despite the growing interest in small animal emission tomography, little scientific information exists about the accuracy of these correction methods on smaller size objects, and what level of correction is required. The purpose of this work is to determine the role of attenuation and scatter corrections as a function of object size through simulations. The simulations were performed using Interactive Data Language (IDL) and a Monte Carlo based package, Geant4 application for emission tomography (GATE). In IDL simulations, PET and SPECT data acquisition were modeled in the presence of attenuation. A mathematical emission and attenuation phantom approximating a thorax slice and slices from real PET/CT data were scaled to 5 different sizes (i.e., human, dog, rabbit, rat and mouse). The simulated emission data collected from these objects were reconstructed. The reconstructed images, with and without attenuation correction, were compared to the ideal (i.e., non-attenuated) reconstruction. Next, using GATE, scatter fraction values (the ratio of the scatter counts to the total counts) of PET and SPECT scanners were measured for various sizes of NEMA (cylindrical phantoms representing small animals and human), MOBY (realistic mouse/rat model) and XCAT (realistic human model

WE-H-206-02: Recent Advances in Multi-Modality Molecular Imaging of Small Animals

Energy Technology Data Exchange (ETDEWEB)

Tsui, B. [Johns Hopkins University (United States)

2016-06-15

to biomedical research during the past decade. The initial development was an extension of clinical PET/CT and SPECT/CT from human to small animals and combine the unique functional information obtained from PET and SPECT with anatomical information provided by the CT in registered multi-modality images. The requirements to image a mouse whose size is an order of magnitude smaller than that of a human have spurred advances in new radiation detector technologies, novel imaging system designs and special image reconstruction and processing techniques. Examples are new detector materials and designs with high intrinsic resolution, multi-pinhole (MPH) collimator design for much improved resolution and detection efficiency compared to the conventional collimator designs in SPECT, 3D high-resolution and artifact-free MPH and sparse-view image reconstruction techniques, and iterative image reconstruction methods with system response modeling for resolution recovery and image noise reduction for much improved image quality. The spatial resolution of PET and SPECT has improved from ∼6–12 mm to ∼1 mm a few years ago to sub-millimeter today. A recent commercial small animal SPECT system has achieved a resolution of ∼0.25 mm which surpasses that of a state-of-art PET system whose resolution is limited by the positron range. More recently, multimodality SA PET/MRI and SPECT/MRI systems have been developed in research laboratories. Also, multi-modality SA imaging systems that include other imaging modalities such as optical and ultrasound are being actively pursued. In this presentation, we will provide a review of the development, recent advances and future outlook of multi-modality molecular imaging of small animals. Learning Objectives: To learn about the two major multi-modality molecular imaging techniques of small animals. To learn about the spatial resolution achievable by the molecular imaging systems for small animal today. To learn about the new multi

WE-H-206-02: Recent Advances in Multi-Modality Molecular Imaging of Small Animals

International Nuclear Information System (INIS)

Tsui, B.

2016-01-01

to biomedical research during the past decade. The initial development was an extension of clinical PET/CT and SPECT/CT from human to small animals and combine the unique functional information obtained from PET and SPECT with anatomical information provided by the CT in registered multi-modality images. The requirements to image a mouse whose size is an order of magnitude smaller than that of a human have spurred advances in new radiation detector technologies, novel imaging system designs and special image reconstruction and processing techniques. Examples are new detector materials and designs with high intrinsic resolution, multi-pinhole (MPH) collimator design for much improved resolution and detection efficiency compared to the conventional collimator designs in SPECT, 3D high-resolution and artifact-free MPH and sparse-view image reconstruction techniques, and iterative image reconstruction methods with system response modeling for resolution recovery and image noise reduction for much improved image quality. The spatial resolution of PET and SPECT has improved from ∼6–12 mm to ∼1 mm a few years ago to sub-millimeter today. A recent commercial small animal SPECT system has achieved a resolution of ∼0.25 mm which surpasses that of a state-of-art PET system whose resolution is limited by the positron range. More recently, multimodality SA PET/MRI and SPECT/MRI systems have been developed in research laboratories. Also, multi-modality SA imaging systems that include other imaging modalities such as optical and ultrasound are being actively pursued. In this presentation, we will provide a review of the development, recent advances and future outlook of multi-modality molecular imaging of small animals. Learning Objectives: To learn about the two major multi-modality molecular imaging techniques of small animals. To learn about the spatial resolution achievable by the molecular imaging systems for small animal today. To learn about the new multi

Combination of radiological and nuclear medical imaging in animals: an overview about the today's possibilities

International Nuclear Information System (INIS)

Behe, M.; Keil, B.; Kiessling, A.; Heverhagen, J.T.; Alfke, H.; Boehm, I.; Gotthardt, M.

2007-01-01

Molecular imaging of small animals has made considerable progress in the last years. Various research fields are interested in imaging small animals due to the lower numbers of animals per experiment. This has advantages with respect to financial, ethical and research aspects. Non-invasive imaging allows examination of one animal several times during the same experiment. This makes it possible to follow a pathological process in the same animal over time. However, the radiological methods used such as magnetic resonance imaging or computed tomography as well as the nuclear medicine methods such as single photon emission computed tomography or positron emission tomography suffer from disadvantages. Molecular aspects are limited in the radiological methods while anatomical localization is difficult in nuclear medicine. The fusion of these methods leads to additional information. This review shows today's possibilities with their advantages as well as disadvantages. (orig.)

Scanning multiple mice in a small-animal PET scanner: Influence on image quality

International Nuclear Information System (INIS)

Siepel, Francoise J.; Lier, Monique G.J.T.B. van; Chen Mu; Disselhorst, Jonathan A.; Meeuwis, Antoi P.W.; Oyen, Wim J.G.; Boerman, Otto C.; Visser, Eric P.

2010-01-01

To achieve high throughput in small-animal positron emission tomography (PET), it may be advantageous to scan more than one animal in the scanner's field of view (FOV) at the same time. However, due to the additional activity and increase of Poisson noise, additional attenuating mass, extra photon scattering, and radial or axial displacement of the animals, a deterioration of image quality can be expected. In this study, the NEMA NU 4-2008 image quality (NU4IQ) phantom and up to three FDG-filled cylindrical 'mouse phantoms' were positioned in the FOV of the Siemens Inveon small-animal PET scanner to simulate scans with multiple mice. Five geometrical configurations were examined. In one configuration, the NU4IQ phantom was scanned separately and placed in the center of the FOV (1C). In two configurations, a mouse phantom was added with both phantoms displaced radially (2R) or axially (2A). In two other configurations, the NU4IQ phantom was scanned along with three mouse phantoms with all phantoms displaced radially (4R), or in a combination of radial and axial displacement (2R2A). Images were reconstructed using ordered subset expectation maximization in 2 dimensions (OSEM2D) and maximum a posteriori (MAP) reconstruction. Image quality parameters were obtained according to the NEMA NU 4-2008 guidelines. Optimum image quality was obtained for the 1C geometry. Image noise increased by the addition of phantoms and was the largest for the 4R configuration. Spatial resolution, reflected in the recovery coefficients for the FDG-filled rods, deteriorated by radial displacement of the NU4IQ phantom (2R, 2R2A, and 4R), most strongly for OSEM2D, and to a smaller extent for MAP reconstructions. Photon scatter, as indicated by the spill-over ratios in the non-radioactive water- and air-filled compartments, increased by the addition of phantoms, most strongly for the 4R configuration. Application of scatter correction substantially lowered the spill-over ratios, but caused an

Studies on micro-domain structure in segmented polyether polyurethane-ureas by positron annihilation lifetime and small-angle X-ray scattering

International Nuclear Information System (INIS)

Yin Chuanyuan; Gu Qingchao

1997-01-01

The micro-domain structure of segmented polyether polyurethane-ureas is investigated by means of positron annihilation lifetime spectroscopy, small-angle X-ray scattering and differential scanning calorimetry. The experimental results show that the decrease in the domain volume and free volume results from the increase in the hard segment (polyurethane-urea segment) contents as the number-average molecular weight M n -bar of the soft segments (polyethylene glycol segments) is the same, and that the increase in domain volume and free volume result from the increase in the M n -bar of the soft segments when the hard segment content is the same or nearly the same. These results demonstrate that positron annihilation lifetime spectroscopy is a sensitive technique to probe the micro-domain structure in polymers

Attenuation correction for freely moving small animal brain PET studies based on a virtual scanner geometry

International Nuclear Information System (INIS)

Angelis, G I; Kyme, A Z; Ryder, W J; Fulton, R R; Meikle, S R

2014-01-01

Attenuation correction in positron emission tomography brain imaging of freely moving animals is a very challenging problem since the torso of the animal is often within the field of view and introduces a non negligible attenuating factor that can degrade the quantitative accuracy of the reconstructed images. In the context of unrestrained small animal imaging, estimation of the attenuation correction factors without the need for a transmission scan is highly desirable. An attractive approach that avoids the need for a transmission scan involves the generation of the hull of the animal’s head based on the reconstructed motion corrected emission images. However, this approach ignores the attenuation introduced by the animal’s torso. In this work, we propose a virtual scanner geometry which moves in synchrony with the animal’s head and discriminates between those events that traversed only the animal’s head (and therefore can be accurately compensated for attenuation) and those that might have also traversed the animal’s torso. For each recorded pose of the animal’s head a new virtual scanner geometry is defined and therefore a new system matrix must be calculated leading to a time-varying system matrix. This new approach was evaluated on phantom data acquired on the microPET Focus 220 scanner using a custom-made phantom and step-wise motion. Results showed that when the animal’s torso is within the FOV and not appropriately accounted for during attenuation correction it can lead to bias of up to 10% . Attenuation correction was more accurate when the virtual scanner was employed leading to improved quantitative estimates (bias < 2%), without the need to account for the attenuation introduced by the extraneous compartment. Although the proposed method requires increased computational resources, it can provide a reliable approach towards quantitatively accurate attenuation correction for freely moving animal studies. (paper)

Positron emission tomography (PET) study of the alterations in brain pharmacokinetics of methamphetamine in methamphetamine sensitized animals

International Nuclear Information System (INIS)

Nakamura, Hitoshi

2001-01-01

I investigated the differences in brain pharmacokinetics of [ 11 C]methamphetamine ([ 11 C]MAP) in normal and MAP sensitized animals using positron emission tomography (PET). [ 11 C]MAP was synthesized by an automated on-line [ 11 C]methylation system. I newly produced MAP sensitized dog and monkey by repeated MAP treatment. The maximal level of accumulation of [ 11 C]MAP in the sensitized dog brain was 1.4 times higher than that in the control. This result suggests the changes in the pharmacokinetic profile of MAP in the brain affect the development or expression of MAP-induced behavioral sensitization. However, the overaccumulation of [ 11 C]MAP in the sensitized monkey brain was not observed due to the influence of anesthesia. (author)

Positron emission tomography (PET) study of the alterations in brain pharmacokinetics of methamphetamine in methamphetamine sensitized animals

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Hitoshi [Tohoku Univ., Sendai (Japan). Hospital

2001-08-01

I investigated the differences in brain pharmacokinetics of [{sup 11}C]methamphetamine ([{sup 11}C]MAP) in normal and MAP sensitized animals using positron emission tomography (PET). [{sup 11}C]MAP was synthesized by an automated on-line [{sup 11}C]methylation system. I newly produced MAP sensitized dog and monkey by repeated MAP treatment. The maximal level of accumulation of [{sup 11}C]MAP in the sensitized dog brain was 1.4 times higher than that in the control. This result suggests the changes in the pharmacokinetic profile of MAP in the brain affect the development or expression of MAP-induced behavioral sensitization. However, the overaccumulation of [{sup 11}C]MAP in the sensitized monkey brain was not observed due to the influence of anesthesia. (author)

An integrated multimodality image-guided robot system for small-animal imaging research

International Nuclear Information System (INIS)

Hsu, Wen-Lin; Hsin Wu, Tung; Hsu, Shih-Ming; Chen, Chia-Lin; Lee, Jason J.S.; Huang, Yung-Hui

2011-01-01

We design and construct an image-guided robot system for use in small-animal imaging research. This device allows the use of co-registered small-animal PET-MRI images to guide the movements of robotic controllers, which will accurately place a needle probe at any predetermined location inside, for example, a mouse tumor, for biological readouts without sacrificing the animal. This system is composed of three major components: an automated robot device, a CCD monitoring mechanism, and a multimodality registration implementation. Specifically, the CCD monitoring mechanism was used for correction and validation of the robot device. To demonstrate the value of the proposed system, we performed a tumor hypoxia study that involved FMISO small-animal PET imaging and the delivering of a pO 2 probe into the mouse tumor using the image-guided robot system. During our evaluation, the needle positioning error was found to be within 0.153±0.042 mm of desired placement; the phantom simulation errors were within 0.693±0.128 mm. In small-animal studies, the pO 2 probe measurements in the corresponding hypoxia areas showed good correlation with significant, low tissue oxygen tensions (less than 6 mmHg). We have confirmed the feasibility of the system and successfully applied it to small-animal investigations. The system could be easily adapted to extend to other biomedical investigations in the future.

Instrumentation for positron emission tomography

International Nuclear Information System (INIS)

Budinger, T.F.; Derenzo, S.E.; Huesman, R.H.

1984-01-01

Positron emission tomography with a spatial resolution of 2 mm full width at half maximum for quantitation in regions of interest 4 mm in diameter will become possible with the development of detectors that achieve ultrahigh resolution. Improved resolution will be possible using solid-state photodetectors for crystal identification or photomultiplier tubes with many small electron multipliers. Temporal resolution of 2 seconds and gating of cyclic events can be accomplished if statistical requirements are met. The major physical considerations in achieving high-resolution positron emission tomography are the degradation in resolution resulting from positron range, emission angle, parallax error, detector sampling density, the sensitivity of various detector materials and packing schemes, and the tradeoff between temporal resolution and statistical accuracy. The accuracy of data required for physiological models depends primarily on the fidelity of spatial sampling independent of statistical constraints

Positron-molecule interactions and corresponding positron attachment to molecules. As a basis for positron emission tomography (PET)

International Nuclear Information System (INIS)

Tachikawa, Masanori; Kimura, Mineo; Pichl, Lukas

2007-01-01

Through positron and electron interactions, they annihilate emitting primarily two gamma rays with 180-degree opposite directions. Positron spectroscopy using the characteristics of these gamma rays has been employed for analyzing various properties of material as well as for positron emission tomography (PET). However, its fundamental physics of positron-electron interactions and resulting features of emitting gamma rays are not well understood. By obtaining better understanding of positron interactions, it should become possible to provide the firm bases for positron spectroscopy in finer accuracy and quality. Here, we propose a significant mechanism for positron annihilation through positron attachment process, which may help increase the quality of positron spectroscopy. (author)

Positron annihilation characterization of nanostructured ferritic alloys

International Nuclear Information System (INIS)

Alinger, M.J.; Glade, S.C.; Wirth, B.D.; Odette, G.R.; Toyama, T.; Nagai, Y.; Hasegawa, M.

2009-01-01

Nanostructured ferritic alloys (NFAs) were produced by mechanically alloying Fe-14Cr-3W-0.4Ti and 0.25Y 2 O 3 (wt%) powders followed by hot isostatic pressing consolidation at 850, 1000 and 1150 deg. C. Positron annihilation lifetime and orbital momentum spectroscopy measurements are in qualitative agreement with small angle neutron scattering, transmission electron microscopy and atom probe tomography observations, indicating that up to 50% of the annihilations occur at high densities of Y-Ti-O enriched nm-scale features (NFs). Some annihilations may also occur in small cavities. In Y-free control alloys, that do not contain NFs, positrons primarily annihilate in the Fe-Cr matrix and at features such as dislocations, while a small fraction annihilate in large cavities or Ar bubbles.

Implementation of immobilization accessories for positioning of small animals for radiation therapy

International Nuclear Information System (INIS)

Vettorato, M.C.; Girotto, C.H.; Fogaça, J.L.; Vulcano, L.C.; Fernandes, M.A.R.

2017-01-01

Radiation therapy is a modality that is presenting great advances in veterinary medicine worldwide. In Brazil, this therapeutic option is underachieved. The success of this method depends on several factors, including the use of appropriate accessories for protection and immobilization of patients. For the immobilization of small animals during treatment, in addition to sedation and anesthesia, immobilizing accessories, similar to those used in human radiotherapy, are used. This study aimed to present proposals for immobilizing accessories adapted to the positioning of small animals in order to be used in radiotherapy planning. In order to achieve results, accessories were made and tested in a living animal simulating a radiotherapy planning, which proved to be favorable to use in positioning small animals undergoing radiotherapy and for implementation processes. (author)

Implementation of immobilization accessories for positioning of small animals for radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Vettorato, M.C.; Girotto, C.H.; Fogaça, J.L.; Vulcano, L.C.; Fernandes, M.A.R., E-mail: m_vettorato@hotmail.com [Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Botucatu, SP (Brazil)

2017-11-15

Radiation therapy is a modality that is presenting great advances in veterinary medicine worldwide. In Brazil, this therapeutic option is underachieved. The success of this method depends on several factors, including the use of appropriate accessories for protection and immobilization of patients. For the immobilization of small animals during treatment, in addition to sedation and anesthesia, immobilizing accessories, similar to those used in human radiotherapy, are used. This study aimed to present proposals for immobilizing accessories adapted to the positioning of small animals in order to be used in radiotherapy planning. In order to achieve results, accessories were made and tested in a living animal simulating a radiotherapy planning, which proved to be favorable to use in positioning small animals undergoing radiotherapy and for implementation processes. (author)

Positron emission tomography imaging of gene expression

International Nuclear Information System (INIS)

Tang Ganghua

2001-01-01

The merging of molecular biology and nuclear medicine is developed into molecular nuclear medicine. Positron emission tomography (PET) of gene expression in molecular nuclear medicine has become an attractive area. Positron emission tomography imaging gene expression includes the antisense PET imaging and the reporter gene PET imaging. It is likely that the antisense PET imaging will lag behind the reporter gene PET imaging because of the numerous issues that have not yet to be resolved with this approach. The reporter gene PET imaging has wide application into animal experimental research and human applications of this approach will likely be reported soon

The biological application of small animal PET imaging

International Nuclear Information System (INIS)

Myers, Ralph

2001-01-01

The short history of small animal PET is reviewed in the context of its application in the laboratory. Early work has demonstrated a role for the technique in both drug development and in the in vivo monitoring of neuroreceptor function with time. As spatial resolution approaches 1 mm, challenges in quantification remain. However, the ability to carry out animal PET studies that are analogous to human PET will form an important bridge between laboratory and clinical sciences

Pre-clinical research in small animals using radiotherapy technology. A bidirectional translational approach

International Nuclear Information System (INIS)

Tillner, Falk; Buetof, Rebecca; Krause, Mechthild; Enghardt, Wolfgang; Helmholtz-Zentrum Dresden-Rossendorf, Dresden; Technische Univ. Dresden; Helmholtz-Zentrum Dresden-Rossendorf, Dresden

2014-01-01

For translational cancer research, pre-clinical in-vivo studies using small animals have become indispensable in bridging the gap between in-vitro cell experiments and clinical implementation. When setting up such small animal experiments, various biological, technical and methodical aspects have to be considered. In this work we present a comprehensive topical review based on relevant publications on irradiation techniques used for pre-clinical cancer research in mice and rats. Clinical radiotherapy treatment devices for the application of external beam radiotherapy and brachytherapy as well as dedicated research irradiation devices are feasible for small animal irradiation depending on the animal model and the experimental goals. In this work, appropriate solutions for the technological transfer of human radiation oncology to small animal radiation research are summarised. Additionally, important information concerning the experimental design is provided such that reliable and clinically relevant results can be attained.

Pre-clinical research in small animals using radiotherapy technology. A bidirectional translational approach

Energy Technology Data Exchange (ETDEWEB)

Tillner, Falk; Buetof, Rebecca [Technische Univ. Dresden (Germany). OncoRay - National Center for Radiation Research in Oncology; Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Univ. Dresden (Germany). Dept. of Radiation Oncology; Thute, Prasad [Technische Univ. Dresden (Germany). OncoRay - National Center for Radiation Research in Oncology; Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Krause, Mechthild [Technische Univ. Dresden (Germany). OncoRay - National Center for Radiation Research in Oncology; Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Univ. Dresden (Germany). Dept. of Radiation Oncology; German Cancer Consortium (DKTK), Dresden (Germany); German Cancer Research Center (DKFZ), Heidelberg (Germany); Enghardt, Wolfgang [Technische Univ. Dresden (Germany). OncoRay - National Center for Radiation Research in Oncology; Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Univ. Dresden (Germany). Dept. of Radiation Oncology; Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Radiooncology

2014-07-01

For translational cancer research, pre-clinical in-vivo studies using small animals have become indispensable in bridging the gap between in-vitro cell experiments and clinical implementation. When setting up such small animal experiments, various biological, technical and methodical aspects have to be considered. In this work we present a comprehensive topical review based on relevant publications on irradiation techniques used for pre-clinical cancer research in mice and rats. Clinical radiotherapy treatment devices for the application of external beam radiotherapy and brachytherapy as well as dedicated research irradiation devices are feasible for small animal irradiation depending on the animal model and the experimental goals. In this work, appropriate solutions for the technological transfer of human radiation oncology to small animal radiation research are summarised. Additionally, important information concerning the experimental design is provided such that reliable and clinically relevant results can be attained.

Slow positron beam production by a 14 MeV C.W. electron accelerator

Science.gov (United States)

Begemann, M.; Gräff, G.; Herminghaus, H.; Kalinowsky, H.; Ley, R.

1982-10-01

A 14 MeV c.w. electron accelerator is used for pair production in a tungsten target of 0.7 radiation lengths thickness. A small fraction of the positrons is thermalized and diffuses out of the surface ofsurface of a well annealed tungsten foil coated with MgO which is positioned immediately behind the target. The slow positrons are extracted from the target region and magnetically guided over a distance of 10 m onto a channelplate multiplier at the end of an S-shaped solenoid. The positrons are identified by their annihilation radiation using two NaI-detectors. The intensity of the slow positrons is proportional to the accelerator electron beam current. The maximum intensity of 2.2 × 10 5 slow positrons per second reaching thedetector at an accelerator current of 15 μA was limited by the power deposited in the uncooled target. The energy of the positrons is concentrated in a small region at about 1 eV and clearly demonstrates the emission of thermal positrons.

Slow positron beam production by a 14 MeV c.w. electron accelerator

International Nuclear Information System (INIS)

Begemann, M.; Graeff, G.; Herminghaus, H.; Kalinowsky, H.; Ley, R.

1982-01-01

A 14 MeV c.w. electron accelerator is used for pair production in a tungsten target of 0.7 radiation lengths thickness. A small fraction of the positrons is thermalized and diffuses out of the surface of a well annealed tungsten foil coated with MgO which is positioned immediately behind the target. The slow positrons are extracted from the target region and magnetically guided over a distance of 10 m onto a channelplate multiplier at the end of an S-shaped solenoid. The positrons are identified by their annihilation radiation using two Nal-detectors. The intensity of the slow positrons is proportional to the accelerator electron beam current. The maximum intensity of 2.2 x 10 5 slow positrons per second reaching the detector at an accelerator current of 15 μA was limited by the power deposited in the uncooled target. The energy of the positrons is concentrated in a small region at about 1 eV and clearly demonstrates the emission of thermal positrons. (orig.)

New positron annihilation spectroscopy techniques for thick materials

International Nuclear Information System (INIS)

Selim, F.A.; Wells, D.P.; Harmon, J.F.; Kwofie, J.; Erikson, G.; Roney, T.

2003-01-01

The Idaho Accelerator Center (IAC) has developed new techniques for positron annihilation spectroscopy (PAS) by using highly penetrating γ-rays to create positrons inside the material via pair production. Two sources of γ-rays have been employed. Bremsstrahlung beams from small-electron linacs (6 MeV) were used to generate positrons inside the material to perform Doppler-broadening spectroscopy. A 2 MeV proton beam was used to obtain coincident γ-rays from 27 Al target and enable lifetime and Doppler-broadening spectroscopy. This technique successfully measured stress/strain in thick samples, and showed promise to extend PAS into a variety of applications

Development of a data acquisition architecture with distributed synchronization for a Positron Emission Tomography system with integrated front-end.

OpenAIRE

Aliaga Varea, Ramón José

2016-01-01

[EN] Positron Emission Tomography (PET) is a non-invasive nuclear medical imaging modality that makes it possible to observe the distribution of metabolic substances within a patient's body after marking them with radioactive isotopes and arranging an annular scanner around him in order to detect their decays. The main applications of this technique are the detection and tracing of tumors in cancer patients and metabolic studies with small animals. The Electronic Design for Nuclear Applic...

Management of occupational health risks in small-animal veterinary practices.

Science.gov (United States)

D'Souza, Eva; Barraclough, Richard; Fishwick, David; Curran, Andrew

2009-08-01

Small-animal work is a major element of veterinary practice in the UK and may be hazardous, with high levels of work-related injuries and ill-health reported in Australia and USA. There are no studies addressing the management of occupational health risks arising from small-animal work in the UK. To investigate the sources of health and safety information used and how health and safety and 12 specific occupational health risks are managed by practices. A cross-sectional postal survey of all small-animal veterinary practices in Hampshire. A response was mandatory as this was a Health & Safety Executive (HSE) inspection activity. A total of 118 (100%) practices responded of which 93 were eligible for inclusion. Of these, 99 and 86%, respectively, were aware of the Royal College of Veterinary Surgeons (RCVS) practice standards and had British Small Animal Veterinary Association (BSAVA) staff members, while only 51% had previous contact with HSE (publications, advice and visit). Ninety per cent had health and safety policies, but only 31% had trained responsible staff in health and safety. Specific health hazards such as occupational allergens and computer use were relatively overlooked both by practices and the RCVS/BSAVA guidance available in 2002. Failings in active health risk management systems could be due to a lack of training to ensure competence in those with responsibilities. Practices rely on guidance produced by their professional bodies. Current RCVS guidance, available since 2005, has remedied some previous omissions, but further improvements are recommended.

Pre-clinical research in small animals using radiotherapy technology--a bidirectional translational approach.

Science.gov (United States)

Tillner, Falk; Thute, Prasad; Bütof, Rebecca; Krause, Mechthild; Enghardt, Wolfgang

2014-12-01

For translational cancer research, pre-clinical in-vivo studies using small animals have become indispensable in bridging the gap between in-vitro cell experiments and clinical implementation. When setting up such small animal experiments, various biological, technical and methodical aspects have to be considered. In this work we present a comprehensive topical review based on relevant publications on irradiation techniques used for pre-clinical cancer research in mice and rats. Clinical radiotherapy treatment devices for the application of external beam radiotherapy and brachytherapy as well as dedicated research irradiation devices are feasible for small animal irradiation depending on the animal model and the experimental goals. In this work, appropriate solutions for the technological transfer of human radiation oncology to small animal radiation research are summarised. Additionally, important information concerning the experimental design is provided such that reliable and clinically relevant results can be attained. Copyright © 2014. Published by Elsevier GmbH.

Positron-containing systems and positron diagnostics

International Nuclear Information System (INIS)

1978-01-01

The results of the experimental and theoretical investigations are presented. Considered are quantum-mechanical calculations of wave functions describing the states of positron-containing atomic systems and of cross-sections of the processes characterizing different interactions, and also the calculations of the behaviour of positrons in gases in the presence of an electric field. The results of experimental tests are presented by the data describing the behaviour of positrons and positronium in liquids, polymers and elastomers, complex oxides and in different solids. New equipment and systems developed on the basis of current studies are described. Examined is a possibility of applying the methods of model and effective potentials for studying the bound states of positron systems and for calculating cross-sections of elementary processes of elastic and inelastic collisions with a positron involved. The experimental works described indicate new possibilities of the positron diagnosis method: investigation of thin layers and films of semiconductor materials, defining the nature of chemical bonds in semiconductors, determination of the dislocation density in deformed semiconductors, derivation of important quantitative information of the energy states of radiation defects in them

Polarization Study for NLC Positron Source Using EGS4

Energy Technology Data Exchange (ETDEWEB)

Liu, James C

2000-09-20

SLAC is exploring a polarized positron source to study new physics for the NLC project. The positron source envisioned in this paper consists of a polarized electron source, a 50-MeV electron accelerator, a thin target less-than-or-equal-to 0.2 radiation length for positron production, and a capture system for high-energy, small angular divergence positrons. The EGS4 code was used to study the yield, energy spectra, emission-angle distribution, and the mean polarization of the positrons emanating from W-Re and Ti targets hit by longitudinally polarized electron and photon beams. To account for polarization within the EGS4 code a method devised by Flottmann was used, which takes into account polarization transfer for pair production, bremsstrahlung, and Compton interactions. A mean polarization of 0.85 for positrons with energies greater than 25 MeV was obtained. Most of the high-energy positrons were emitted within a forward angle of 20 degrees. The yield of positrons above 25 MeV per incident photon was 0.034, which was about 70 times higher than that obtained with an electron beam.

Hyperpolarized singlet NMR on a small animal imaging system

DEFF Research Database (Denmark)

Laustsen, Christoffer; Pileio, Giuseppe; Tayler, Michael C. D.

2012-01-01

Nuclear spin hyperpolarization makes a significant advance toward overcoming the sensitivity limitations of in vivo magnetic resonance imaging, particularly in the case of low-gamma nuclei. The sensitivity may be improved further by storing the hyperpolarization in slowly relaxing singlet...... populations of spin- 1/2 pairs. Here, we report hyperpolarized 13C spin order transferred into and retrieved from singlet spin order using a small animal magnetic resonance imaging scanner. For spins in sites with very similar chemical shifts, singlet spin order is sustained in high magnetic field without...... requiring strong radiofrequency irradiation. The demonstration of robust singlet-to-magnetization conversion, and vice versa, on a small animal scanner, is promising for future in vivo and clinical deployments....

Marketing small animal theriogenology services--one perspective.

Science.gov (United States)

Barber, J A

2007-08-01

Once a decision is made to add small animal theriogenology services to a practice, marketing strategies must be developed and implemented to attract clients to the new services. Marketing strategies for the niche market of theriogenology include start-up marketing methods, referral programs, internal marketing, and continued marketing. Marketing theriogenology services is a dynamic, ongoing process that never ends.

Bremsstrahlung Based Positron Annihilation Spectroscopy for Material Defect Analysis

International Nuclear Information System (INIS)

Selim, F.A.; Wells, D.P.; Harmon, F.; Kwofie, J.; Lancaster, G.; Jones, J.L.

2003-01-01

The Idaho Accelerator Center (IAC) has developed new techniques for Positron Annihilation Spectroscopy (PAS) using highly penetrating γ-rays to create positrons inside the material via pair production. γ-Ray induced positron annihilation spectroscopy can provide highly penetrating probes for material characterization and defect analysis. Bremsstrahlung beams from small, pulsed electron Linacs (6 MeV) have been used to bombard the materials to generate positrons, which annihilate with the material electrons emitting 511 keV radiation. We have also synchronized bremsstrahlung pulses with laser irradiation pulses to study dynamic structural changes in material. In addition, we have developed another method using (p,γ) reactions from a 2 MeV proton beam, which induce coincident γ-rays to perform positron life-time spectroscopy. We have showed the feasibility of extending PAS into thick samples and a wide variety of materials and industrial applications

Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks

Science.gov (United States)

Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

2005-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel, and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. New simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. Furthermore, the nonlinear fluctuation amplitudes of densities, currents, and electric and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper at a comparable simulation time. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. In addition, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by tine Weibel instability scale proportionally to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform, small-scale magnetic fields, which contribute to the electron s (positron s) transverse deflection behind the jet head. This

Simulation of channeling and radiation of 855 MeV electrons and positrons in a small-amplitude short-period bent crystal

Energy Technology Data Exchange (ETDEWEB)

Korol, Andrei V., E-mail: korol@mbnexplorer.com [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); Bezchastnov, Victor G. [A.F. Ioffe Physical-Technical Institute, Politechnicheskaya Str. 26, 194021 St. Petersburg (Russian Federation); Peter the Great St. Petersburg Polytechnic University, Politechnicheskaya 29, 195251 St. Petersburg (Russian Federation); Sushko, Gennady B.; Solov’yov, Andrey V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany)

2016-11-15

Channeling and radiation are studied for the relativistic electrons and positrons passing through a Si crystal periodically bent with a small amplitude and a short period. Comprehensive analysis of the channeling process for various bending amplitudes is presented on the grounds of numerical simulations. The features of the channeling are highlighted and elucidated within an analytically developed continuous potential approximation. The radiation spectra are computed and discussed.

Progress on dedicated animal PET

International Nuclear Information System (INIS)

Liu Wei

2002-01-01

Positron emission tomography, as the leading technology providing molecular imaging of biological processes, is widely used on living laboratory animals. High-resolution dedicated animal PET scanners have been developed. Although the dedicated animal PET faces obstacles and challenges, this advanced technology would play an important role in molecular biomedicine researches, such as diseases study, medicine development, and gene therapy

Hyperspectral small animal fluorescence imaging: spectral selection imaging

Science.gov (United States)

Leavesley, Silas; Jiang, Yanan; Patsekin, Valery; Hall, Heidi; Vizard, Douglas; Robinson, J. Paul

2008-02-01

Molecular imaging is a rapidly growing area of research, fueled by needs in pharmaceutical drug-development for methods for high-throughput screening, pre-clinical and clinical screening for visualizing tumor growth and drug targeting, and a growing number of applications in the molecular biology fields. Small animal fluorescence imaging employs fluorescent probes to target molecular events in vivo, with a large number of molecular targeting probes readily available. The ease at which new targeting compounds can be developed, the short acquisition times, and the low cost (compared to microCT, MRI, or PET) makes fluorescence imaging attractive. However, small animal fluorescence imaging suffers from high optical scattering, absorption, and autofluorescence. Much of these problems can be overcome through multispectral imaging techniques, which collect images at different fluorescence emission wavelengths, followed by analysis, classification, and spectral deconvolution methods to isolate signals from fluorescence emission. We present an alternative to the current method, using hyperspectral excitation scanning (spectral selection imaging), a technique that allows excitation at any wavelength in the visible and near-infrared wavelength range. In many cases, excitation imaging may be more effective at identifying specific fluorescence signals because of the higher complexity of the fluorophore excitation spectrum. Because the excitation is filtered and not the emission, the resolution limit and image shift imposed by acousto-optic tunable filters have no effect on imager performance. We will discuss design of the imager, optimizing the imager for use in small animal fluorescence imaging, and application of spectral analysis and classification methods for identifying specific fluorescence signals.

[F18]-FDG imaging of experimental animal tumours using a hybrid gamma-camera

International Nuclear Information System (INIS)

Lausson, S.; Maurel, G.; Kerrou, K.; Montravers, F.; Petegnief, Y.; Talbot, J.N.; Fredelizi, D.

2001-01-01

Positron emission tomography (PET) has been widely used in clinical studies. This technology permits detection of compounds labelled with positron emitting radionuclides and in particular, [F18]-fluorodeoxyglucose ([F18]-FDG).[F18]-FDG uptake and accumulation is generally related to malignancy; some recent works have suggested the usefulness of PET camera dedicated to small laboratory animals (micro-PET). Our study dealt with the feasibility of [F18]-FDG imaging of malignant tumours in animal models by means of an hybrid camera dedicated for human scintigraphy. We evaluated the ability of coincidence detection emission tomography (CDET) using this hybrid camera to visualize in vivo subcutaneous tumours grafted to mice or rats. P815 murine mastocytoma grafted in syngeneic DBA/2 mice resulted with foci of very high FDG uptake. Tumours with a diameter of only 3 mm were clearly visualized. Medullary thyroid cancer provoked by rMTC 6/23 and CA77 lines in syngeneic Wag/Rij rat was also detected. The differentiated CA77 tumours exhibited avidity for [F18]-FDG and a tumour, which was just palpable (diameter lower than 2 mm), was identified. In conclusion, CDET-FDG is a non-invasive imaging tool which can be used to follow grafted tumours in the small laboratory animal, even when their size is smaller than 1 cm. It has the potential to evaluate experimental anticancer treatments in small series of animals by individual follow-up. It offers the opportunity to develop experimental PET research within a nuclear medicine or biophysics department, the shift to a dedicated micro-PET device being subsequently necessary. It is indeed compulsory to strictly follow the rules for non contamination and disinfection of the hybrid camera. (authors)

Positron emission tomographic imaging of cardiac sympathetic innervation and function

International Nuclear Information System (INIS)

Goldstein, D.S.; Chang, P.C.; Eisenhofer, G.; Miletich, R.; Finn, R.; Bacher, J.; Kirk, K.L.; Bacharach, S.; Kopin, I.J.

1990-01-01

Sites of uptake, storage, and metabolism of [ 18 F]fluorodopamine and excretion of [ 18 F]fluorodopamine and its metabolites were visualized using positron emission tomographic (PET) scanning after intravenous injection of the tracer into anesthetized dogs. Radioactivity was concentrated in the renal pelvis, heart, liver, spleen, salivary glands, and gall bladder. Uptake of 18F by the heart resulted in striking delineation of the left ventricular myocardium. Pretreatment with desipramine markedly decreased cardiac positron emission, consistent with dependence of the heart on neuronal uptake (uptake-1) for removal of circulating catecholamines. In reserpinized animals, cardiac positron emission was absent within 30 minutes after injection of [ 18 F]-6-fluorodopamine, demonstrating that the emission in untreated animals was from radioactive labeling of the sympathetic storage vesicles. Decreased positron emission from denervated salivary glands confirmed that the tracer was concentrated in sympathetic neurons. Radioactivity in the gall bladder and urinary system depicted the hepatic and renal excretion of the tracer and its metabolites. Administration of tyramine or nitroprusside increased and ganglionic blockade with trimethaphan decreased the rate of loss of myocardial radioactivity. The results show that PET scanning after administration of [ 18 F]fluorodopamine can be used to visualize sites of sympathetic innervation, follow the metabolism and renal and hepatic excretion of catecholamines, and examine cardiac sympathetic function

Positron Emission Tomography: Current Challenges and Opportunities for Technological Advances in Clinical and Preclinical Imaging Systems

Science.gov (United States)

Vaquero, Juan José; Kinahan, Paul

2017-01-01

Positron emission tomography (PET) imaging is based on detecting two time-coincident high-energy photons from the emission of a positron-emitting radioisotope. The physics of the emission, and the detection of the coincident photons, give PET imaging unique capabilities for both very high sensitivity and accurate estimation of the in vivo concentration of the radiotracer. PET imaging has been widely adopted as an important clinical modality for oncological, cardiovascular, and neurological applications. PET imaging has also become an important tool in preclinical studies, particularly for investigating murine models of disease and other small-animal models. However, there are several challenges to using PET imaging systems. These include the fundamental trade-offs between resolution and noise, the quantitative accuracy of the measurements, and integration with X-ray computed tomography and magnetic resonance imaging. In this article, we review how researchers and industry are addressing these challenges. PMID:26643024

Positron Emission Tomography: Current Challenges and Opportunities for Technological Advances in Clinical and Preclinical Imaging Systems.

Science.gov (United States)

Vaquero, Juan José; Kinahan, Paul

2015-01-01

Positron emission tomography (PET) imaging is based on detecting two time-coincident high-energy photons from the emission of a positron-emitting radioisotope. The physics of the emission, and the detection of the coincident photons, give PET imaging unique capabilities for both very high sensitivity and accurate estimation of the in vivo concentration of the radiotracer. PET imaging has been widely adopted as an important clinical modality for oncological, cardiovascular, and neurological applications. PET imaging has also become an important tool in preclinical studies, particularly for investigating murine models of disease and other small-animal models. However, there are several challenges to using PET imaging systems. These include the fundamental trade-offs between resolution and noise, the quantitative accuracy of the measurements, and integration with X-ray computed tomography and magnetic resonance imaging. In this article, we review how researchers and industry are addressing these challenges.

Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

International Nuclear Information System (INIS)

Wirth, B D; Asoka-Kumar, P; Howell, R H; Odette, G R; Sterne, P A

2001-01-01

Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs and VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime (∼500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs

Small Animal Massage Therapy: A Brief Review and Relevant Observations.

Science.gov (United States)

Formenton, Maira Rezende; Pereira, Marco Aurélio Amador; Fantoni, Denise Tabacchi

2017-12-01

Massage therapy is becoming increasingly popular in human and animal physiotherapy and rehabilitation. Wider application of the technique led to research efforts aimed at providing scientific support to anecdotal beneficial effects, particularly pain relief. Recent studies have shown that massage therapy alters dopamine and serotonin levels, decreases noradrenaline levels, and modulates the immune system. Psychological effects such as reduction of stress and anxiety, with improvement of depressive patients, have been reported in humans. This article set out to review the major aspects of massage therapy based on recent publications on the topic, and to extrapolate concepts and practical aspects described in human physiotherapy to the veterinary patient, particularly the applicability of different techniques in Small Animal Medicine. Indications of massage therapy in small animals include pain relief, orthopedic rehabilitation, Canine Sports Medicine, intensive care, and management of nonspecific edema. Techniques described in this article were originally intended for use in humans and scientific data supporting anecdotal, beneficial effects in domestic animals are still lacking; this fruitful area for research is therefore open to veterinary professionals. Copyright © 2017 Elsevier Inc. All rights reserved.

Preliminary study for small animal preclinical hadrontherapy facility

Energy Technology Data Exchange (ETDEWEB)

Russo, G. [Institute of Molecular Bioimaging and Physiology, IBFM CNR-LATO, Cefalú (Italy); Pisciotta, P., E-mail: pietro.pisciotta@ibfm.cnr.it [Institute of Molecular Bioimaging and Physiology, IBFM CNR-LATO, Cefalú (Italy); National Institute for Nuclear Physics, Laboratori Nazionali del Sud, INFN-LNS, Catania (Italy); Cirrone, G.A.P.; Romano, F. [National Institute for Nuclear Physics, Laboratori Nazionali del Sud, INFN-LNS, Catania (Italy); Cammarata, F.; Marchese, V.; Forte, G.I.; Lamia, D.; Minafra, L.; Bravatá, V. [Institute of Molecular Bioimaging and Physiology, IBFM CNR-LATO, Cefalú (Italy); Acquaviva, R. [University of Catania, Catania (Italy); Gilardi, M.C. [Institute of Molecular Bioimaging and Physiology, IBFM CNR-LATO, Cefalú (Italy); Cuttone, G. [National Institute for Nuclear Physics, Laboratori Nazionali del Sud, INFN-LNS, Catania (Italy)

2017-02-21

Aim of this work is the study of the preliminary steps to perform a particle treatment of cancer cells inoculated in small animals and to realize a preclinical hadrontherapy facility. A well-defined dosimetric protocol was developed to explicate the steps needed in order to perform a precise proton irradiation in small animals and achieve a highly conformal dose into the target. A precise homemade positioning and holding system for small animals was designed and developed at INFN-LNS in Catania (Italy), where an accurate Monte Carlo simulation was developed, using Geant4 code to simulate the treatment in order to choose the best animal position and perform accurately all the necessary dosimetric evaluations. The Geant4 application can also be used to realize dosimetric studies and its peculiarity consists in the possibility to introduce the real target composition in the simulation using the DICOM micro-CT image. This application was fully validated comparing the results with the experimental measurements. The latter ones were performed at the CATANA (Centro di AdroTerapia e Applicazioni Nucleari Avanzate) facility at INFN-LNS by irradiating both PMMA and water solid phantom. Dosimetric measurements were performed using previously calibrated EBT3 Gafchromic films as a detector and the results were compared with the Geant4 simulation ones. In particular, two different types of dosimetric studies were performed: the first one involved irradiation of a phantom made up of water solid slabs where a layer of EBT3 was alternated with two different slabs in a sandwich configuration, in order to validate the dosimetric distribution. The second one involved irradiation of a PMMA phantom made up of a half hemisphere and some PMMA slabs in order to simulate a subcutaneous tumour configuration, normally used in preclinical studies. In order to evaluate the accordance between experimental and simulation results, two different statistical tests were made: Kolmogorov test and

Preliminary study for small animal preclinical hadrontherapy facility

Science.gov (United States)

Russo, G.; Pisciotta, P.; Cirrone, G. A. P.; Romano, F.; Cammarata, F.; Marchese, V.; Forte, G. I.; Lamia, D.; Minafra, L.; Bravatá, V.; Acquaviva, R.; Gilardi, M. C.; Cuttone, G.

2017-02-01

Aim of this work is the study of the preliminary steps to perform a particle treatment of cancer cells inoculated in small animals and to realize a preclinical hadrontherapy facility. A well-defined dosimetric protocol was developed to explicate the steps needed in order to perform a precise proton irradiation in small animals and achieve a highly conformal dose into the target. A precise homemade positioning and holding system for small animals was designed and developed at INFN-LNS in Catania (Italy), where an accurate Monte Carlo simulation was developed, using Geant4 code to simulate the treatment in order to choose the best animal position and perform accurately all the necessary dosimetric evaluations. The Geant4 application can also be used to realize dosimetric studies and its peculiarity consists in the possibility to introduce the real target composition in the simulation using the DICOM micro-CT image. This application was fully validated comparing the results with the experimental measurements. The latter ones were performed at the CATANA (Centro di AdroTerapia e Applicazioni Nucleari Avanzate) facility at INFN-LNS by irradiating both PMMA and water solid phantom. Dosimetric measurements were performed using previously calibrated EBT3 Gafchromic films as a detector and the results were compared with the Geant4 simulation ones. In particular, two different types of dosimetric studies were performed: the first one involved irradiation of a phantom made up of water solid slabs where a layer of EBT3 was alternated with two different slabs in a sandwich configuration, in order to validate the dosimetric distribution. The second one involved irradiation of a PMMA phantom made up of a half hemisphere and some PMMA slabs in order to simulate a subcutaneous tumour configuration, normally used in preclinical studies. In order to evaluate the accordance between experimental and simulation results, two different statistical tests were made: Kolmogorov test and

Preliminary study for small animal preclinical hadrontherapy facility

International Nuclear Information System (INIS)

Russo, G.; Pisciotta, P.; Cirrone, G.A.P.; Romano, F.; Cammarata, F.; Marchese, V.; Forte, G.I.; Lamia, D.; Minafra, L.; Bravatá, V.; Acquaviva, R.; Gilardi, M.C.; Cuttone, G.

2017-01-01

Aim of this work is the study of the preliminary steps to perform a particle treatment of cancer cells inoculated in small animals and to realize a preclinical hadrontherapy facility. A well-defined dosimetric protocol was developed to explicate the steps needed in order to perform a precise proton irradiation in small animals and achieve a highly conformal dose into the target. A precise homemade positioning and holding system for small animals was designed and developed at INFN-LNS in Catania (Italy), where an accurate Monte Carlo simulation was developed, using Geant4 code to simulate the treatment in order to choose the best animal position and perform accurately all the necessary dosimetric evaluations. The Geant4 application can also be used to realize dosimetric studies and its peculiarity consists in the possibility to introduce the real target composition in the simulation using the DICOM micro-CT image. This application was fully validated comparing the results with the experimental measurements. The latter ones were performed at the CATANA (Centro di AdroTerapia e Applicazioni Nucleari Avanzate) facility at INFN-LNS by irradiating both PMMA and water solid phantom. Dosimetric measurements were performed using previously calibrated EBT3 Gafchromic films as a detector and the results were compared with the Geant4 simulation ones. In particular, two different types of dosimetric studies were performed: the first one involved irradiation of a phantom made up of water solid slabs where a layer of EBT3 was alternated with two different slabs in a sandwich configuration, in order to validate the dosimetric distribution. The second one involved irradiation of a PMMA phantom made up of a half hemisphere and some PMMA slabs in order to simulate a subcutaneous tumour configuration, normally used in preclinical studies. In order to evaluate the accordance between experimental and simulation results, two different statistical tests were made: Kolmogorov test and

Technical note - Considerations for MR imaging of small animals

International Nuclear Information System (INIS)

Baker, Martin A.

2011-01-01

Routine clinical veterinary use of MR scanning is becoming more common. This article addresses the major technical considerations for radiographers performing MR examinations on small animals and provides practical advice for scanning techniques.

Dry coupling for whole-body small-animal photoacoustic computed tomography

Science.gov (United States)

Yeh, Chenghung; Li, Lei; Zhu, Liren; Xia, Jun; Li, Chiye; Chen, Wanyi; Garcia-Uribe, Alejandro; Maslov, Konstantin I.; Wang, Lihong V.

2017-04-01

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using a whole-body small-animal ring-shaped photoacoustic computed tomography system. Dry coupling was found to provide image quality comparable to that of conventional water coupling.

Planned Positron Factory project

International Nuclear Information System (INIS)

Okada, Sohei

1990-01-01

The Japan Atomic Energy Research Institute, JAERI, has started, drafting a construction plan for the 'Positron Factory', in which intense energy-controllable monoenergetic positron beams are produced from pair-production reactions caused by high-energy electrons from a linac. The JAERI organized a planning committee to provide a basic picture for the Positron Factory. This article presents an overview of the interactions of positrons, intense positron sources and the research program and facilities planned for the project. The interactions of positrons and intense positron sources are discussed focusing on major characteristics of positrons in different energy ranges. The research program for the Positron Factory is then outlined, focusing on advanced positron annihilation techniques, positron spectroscopy (diffraction, scattering, channeling, microscopy), basic positron physics (exotic particle science), and positron beam technology. Discussion is also made of facilities required for the Positron Factory. (N.K.)

Positron sources

International Nuclear Information System (INIS)

Chehab, R.

1989-01-01

A tentative survey of positron sources is given. Physical processes on which positron generation is based are indicated and analyzed. Explanation of the general features of electromagnetic interactions and nuclear β + decay makes it possible to predict the yield and emittance for a given optical matching system between the positron source and the accelerator. Some kinds of matching systems commonly used - mainly working with solenoidal fields - are studied and the acceptance volume calculated. Such knowledge is helpful in comparing different matching systems. Since for large machines, a significant distance exists between the positron source and the experimental facility, positron emittance has to be preserved during beam transfer over large distances and methods used for that purpose are indicated. Comparison of existing positron sources leads to extrapolation to sources for future linear colliders

Positron-acoustic waves in an electron-positron plasma with an electron beam

International Nuclear Information System (INIS)

Nejoh, Y.N.

1996-01-01

The nonlinear wave structures of large-amplitude positron-acoustic waves are studied in an electron-positron plasma in the presence of an electron beam with finite temperature and hot electrons and positrons. The region where positron-acoustic waves exist is presented by analysing the structure of the pseudopotential. The region depends sensitively on the positron density, the positron temperature and the electron beam temperature. It is shown that the maximum amplitude of the wave decreases as the positron temperature increases, and the region of positron-acoustic waves spreads as the positron temperature increases. 11 refs., 5 figs

Ab initio calculation of positron distribution, ACAR and lifetime in TTF-TCNQ

International Nuclear Information System (INIS)

Ishibashi, Shoji; Kohyama, Masanori

2000-01-01

We have performed ab initio calculations of positron distribution, ACAR and lifetime in the quasi-one-dimensional organic conductor TTF-TCNQ. The electronic structure is obtained within the LDA, while the positron state is calculated either with the LDA or with the GGA. Except the positron lifetime, differences between the LDA and GGA results are rather small. The obtained results are compared with our previous experiments and calculations.

Electrostatic solitons in unmagnetized hot electron-positron-ion plasmas

International Nuclear Information System (INIS)

Mahmood, S.; Ur-Rehman, H.

2009-01-01

Linear and nonlinear electrostatic waves in unmagnetized electron-positron-ion (e-p-i) plasmas are studied. The electrons and positrons are assumed to be isothermal and dynamic while ions are considered to be stationary to neutralize the plasma background only. It is found that both upper (fast) and lower (slow) Langmuir waves can propagates in such a type of pair (e-p) plasma in the presence of ions. The small amplitude electrostatic Korteweg-de Vries (KdV) solitons are also obtained using reductive perturbation method. The electrostatic potential hump structures are found to exist when the temperature of the electrons is larger than the positrons, while the electrostatic potential dips are obtained in the reverse temperature conditions for electrons and positrons in e-p-i plasmas. The numerical results are also shown for illustration. The effects of different ion concentration and temperature ratios of electrons and positrons, on the formation of nonlinear electrostatic potential structures in e-p-i plasmas are also discussed.

Positron sources

International Nuclear Information System (INIS)

Chehab, R.

1994-01-01

A tentative survey of positron sources is given. Physical processes on which positron generation is based are indicated and analyzed. Explanation of the general features of electromagnetic interactions and nuclear β + decay makes it possible to predict the yield and emittance for a given optical matching system between the positron source and the accelerator. Some kinds of matching systems commonly used - mainly working with solenoidal field - are studied and the acceptance volume calculated. Such knowledge is helpful in comparing different matching systems. Since for large machines, a significant distance exists between the positron source and the experimental facility, positron emittance has to be preserved during beam transfer over large distances and methods used for that purpose are indicated. Comparison of existing positron sources leads to extrapolation to sources for future linear colliders. Some new ideas associated with these sources are also presented. (orig.)

Transmission positron microscopes

International Nuclear Information System (INIS)

Doyama, Masao; Kogure, Yoshiaki; Inoue, Miyoshi; Kurihara, Toshikazu; Yoshiie, Toshimasa; Oshima, Ryuichiro; Matsuya, Miyuki

2006-01-01

Immediate and near-future plans for transmission positron microscopes being built at KEK, Tsukuba, Japan, are described. The characteristic feature of this project is remolding a commercial electron microscope to a positron microscope. A point source of electrons kept at a negative high voltage is changed to a point source of positrons kept at a high positive voltage. Positional resolution of transmission microscopes should be theoretically the same as electron microscopes. Positron microscopes utilizing trapping of positrons have always positional ambiguity due to the diffusion of positrons

Application of MOSFET detectors for dosimetry in small animal radiography using short exposure times.

Science.gov (United States)

De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G Allan; Yoshizumi, Terry T

2008-08-01

Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies.

Precise image-guided irradiation of small animals: a flexible non-profit platform

International Nuclear Information System (INIS)

Tillner, Falk; Thute, Prasad; Löck, Steffen; Dietrich, Antje; Fursov, Andriy; Haase, Robert; Lukas, Mathias; Krause, Mechthild; Baumann, Michael; Bütof, Rebecca; Enghardt, Wolfgang; Rimarzig, Bernd; Sobiella, Manfred

2016-01-01

Preclinical in vivo studies using small animals are essential to develop new therapeutic options in radiation oncology. Of particular interest are orthotopic tumour models, which better reflect the clinical situation in terms of growth patterns and microenvironmental parameters of the tumour as well as the interplay of tumours with the surrounding normal tissues. Such orthotopic models increase the technical demands and the complexity of preclinical studies as local irradiation with therapeutically relevant doses requires image-guided target localisation and accurate beam application. Moreover, advanced imaging techniques are needed for monitoring treatment outcome. We present a novel small animal image-guided radiation therapy (SAIGRT) system, which allows for precise and accurate, conformal irradiation and x-ray imaging of small animals. High accuracy is achieved by its robust construction, the precise movement of its components and a fast high-resolution flat-panel detector. Field forming and x-ray imaging is accomplished close to the animal resulting in a small penumbra and a high image quality. Feasibility for irradiating orthotopic models has been proven using lung tumour and glioblastoma models in mice. The SAIGRT system provides a flexible, non-profit academic research platform which can be adapted to specific experimental needs and therefore enables systematic preclinical trials in multicentre research networks. (paper)

Performance evaluation of a rotatory dual-head PET system with 90o increments for small animal imaging

Science.gov (United States)

Meng, F.; Zhu, S.; Li, L.; Wang, J.; Cao, X.; Cao, X.; Chen, X.; Liang, J.

2017-09-01

A rotatory dual-head positron emission tomography (PET) system with 90o increments has been built up by our lab. In this study, a geometric calibration phantom was designed and then used to calibrate the geometric offset of the system. With the geometric calibration, the artifacts in the reconstructed images were greatly eliminated. Then, we measured the imaging performance including resolution, sensitivity and image quality. The results showed that the full width at half maximum (FWHMs) of the point source were about 1.1 mm in three directions. The peak absolute sensitivity in the center of the field of view varied from 5.66% to 3.17% when the time window was fixed to 10 ns and the energy window was changed from 200-800 keV to 350-650 keV. The recovery coefficients ranged from 0.13 with a standard deviation of 17.5% to 0.98 with a standard deviation of 15.76%. For the air-filled and water-filled chamber, the spill-over ratio was 14.48% and 15.38%, respectively. The in vivo mouse experiment was carried out and further demonstrated the potential of our system in small animal studies.

Performance evaluation of a rotatory dual-head PET system with 90o increments for small animal imaging

International Nuclear Information System (INIS)

Meng, F.; Zhu, S.; Li, L.; Wang, J.; Cao, X.; Cao, X.; Chen, X.; Liang, J.

2017-01-01

A rotatory dual-head positron emission tomography (PET) system with 90 o increments has been built up by our lab. In this study, a geometric calibration phantom was designed and then used to calibrate the geometric offset of the system. With the geometric calibration, the artifacts in the reconstructed images were greatly eliminated. Then, we measured the imaging performance including resolution, sensitivity and image quality. The results showed that the full width at half maximum (FWHMs) of the point source were about 1.1 mm in three directions. The peak absolute sensitivity in the center of the field of view varied from 5.66% to 3.17% when the time window was fixed to 10 ns and the energy window was changed from 200-800 keV to 350–650 keV. The recovery coefficients ranged from 0.13 with a standard deviation of 17.5% to 0.98 with a standard deviation of 15.76%. For the air-filled and water-filled chamber, the spill-over ratio was 14.48% and 15.38%, respectively. The in vivo mouse experiment was carried out and further demonstrated the potential of our system in small animal studies.

Euthanasia of Small Animals with Nitrogen; Comparison with Intravenous Pentobarbital

OpenAIRE

Quine, John P.; Buckingham, William; Strunin, Leo

1988-01-01

Intravenous pentobarbital (with or without addition of saturated potassium chloride) was compared with nitrogen gas exposure for euthanasia of small animals (dogs, cats, and rabbits) in a humane society environment. Initially, electrocardiographic) and electroencephalographic monitoring were used to establish the time of death in presedated animals given either pentobarbital or exposed to nitrogen; later, nitrogen euthanasia alone was studied. Sedation with acepromazine delayed the effects of...

In vivo small animal imaging: Current status and future prospects

International Nuclear Information System (INIS)

Kagadis, George C.; Loudos, George; Katsanos, Konstantinos; Langer, Steve G.; Nikiforidis, George C.

2010-01-01

The use of small animal models in basic and preclinical sciences constitutes an integral part of testing new pharmaceutical agents prior to commercial translation to clinical practice. Whole-body small animal imaging is a particularly elegant and cost-effective experimental platform for the timely validation and commercialization of novel agents from the bench to the bedside. Biomedical imaging is now listed along with genomics, proteomics, and metabolomics as an integral part of biological and medical sciences. Miniaturized versions of clinical diagnostic modalities, including but not limited to microcomputed tomography, micromagnetic resonance tomography, microsingle-photon-emission tomography, micropositron-emission tomography, optical imaging, digital angiography, and ultrasound, have all greatly improved our investigative abilities to longitudinally study various experimental models of human disease in mice and rodents. After an exhaustive literature search, the authors present a concise and critical review of in vivo small animal imaging, focusing on currently available modalities as well as emerging imaging technologies on one side and molecularly targeted contrast agents on the other. Aforementioned scientific topics are analyzed in the context of cancer angiogenesis and innovative antiangiogenic strategies under-the-way to the clinic. Proposed hybrid approaches for diagnosis and targeted site-specific therapy are highlighted to offer an intriguing glimpse of the future.

Variable-energy positron-beam studies of Ni implanted with He

International Nuclear Information System (INIS)

Lynn, K.G.; Chen, D.M.; Nielsen, B.; Pareja, R.; Myers, S.

1986-01-01

Variable-energy positron-beam studies have been made on well-annealed polycrystalline Ni samples implanted with 30-, 90-, and 180-keV 4 He ions. The positron-annihilation characteristics were measured with a solid-state Ge detector at a number of different incident-positron energies and after isochronal annealing at various temperatures. The Doppler broadening of the annihilation photons was found to be strongly influenced by the 4 He implantations. The data indicate that trapping of the positrons occurred predominantly at small He bubbles. The variation of the broadening with incident-positron energy was sensitive to the depth distribution of the traps. A diffusion model assuming a square concentration-defect profile was developed and analytically fitted to the parametrized momentum data. These fitted results were compared to Monte Carlo range calculations for 4 He in Ni, and fairly good agreement was found. This investigation demonstrates the capabilities of positron annihilation for nondestructive depth profiling in ion-implanted systems. In addition, it establishes parallels between the trapping behavior of positrons and that reported elsewhere for hydrogen, thereby augmenting the present level of understanding of the technologically important trapping of hydrogen by the bubbles

Integration of optical imaging with a small animal irradiator

International Nuclear Information System (INIS)

Weersink, Robert A.; Ansell, Steve; Wang, An; Wilson, Graham; Shah, Duoaud; Lindsay, Patricia E.; Jaffray, David A.

2014-01-01

Purpose: The authors describe the integration of optical imaging with a targeted small animal irradiator device, focusing on design, instrumentation, 2D to 3D image registration, 2D targeting, and the accuracy of recovering and mapping the optical signal to a 3D surface generated from the cone-beam computed tomography (CBCT) imaging. The integration of optical imaging will improve targeting of the radiation treatment and offer longitudinal tracking of tumor response of small animal models treated using the system. Methods: The existing image-guided small animal irradiator consists of a variable kilovolt (peak) x-ray tube mounted opposite an aSi flat panel detector, both mounted on a c-arm gantry. The tube is used for both CBCT imaging and targeted irradiation. The optical component employs a CCD camera perpendicular to the x-ray treatment/imaging axis with a computer controlled filter for spectral decomposition. Multiple optical images can be acquired at any angle as the gantry rotates. The optical to CBCT registration, which uses a standard pinhole camera model, was modeled and tested using phantoms with markers visible in both optical and CBCT images. Optically guided 2D targeting in the anterior/posterior direction was tested on an anthropomorphic mouse phantom with embedded light sources. The accuracy of the mapping of optical signal to the CBCT surface was tested using the same mouse phantom. A surface mesh of the phantom was generated based on the CBCT image and optical intensities projected onto the surface. The measured surface intensity was compared to calculated surface for a point source at the actual source position. The point-source position was also optimized to provide the closest match between measured and calculated intensities, and the distance between the optimized and actual source positions was then calculated. This process was repeated for multiple wavelengths and sources. Results: The optical to CBCT registration error was 0.8 mm. Two

Molecular model for annihilation rates in positron complexes

Energy Technology Data Exchange (ETDEWEB)

Assafrao, Denise [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O. Box 702, 30123-970 Belo Horizonte, MG (Brazil); Department of Applied Mathematics and Theoretical Physics, Queen' s University of Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Walters, H.R. James [Department of Applied Mathematics and Theoretical Physics, Queen' s University of Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Mohallem, Jose R. [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O. Box 702, 30123-970 Belo Horizonte, MG (Brazil); Department of Applied Mathematics and Theoretical Physics, Queen' s University of Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)], E-mail: rachid@fisica.ufmg.br

2008-02-15

The molecular approach for positron interaction with atoms is developed further. Potential energy curves for positron motion are obtained. Two procedures accounting for the nonadiabatic effective positron mass are introduced for calculating annihilation rate constants. The first one takes the bound-state energy eigenvalue as an input parameter. The second is a self-contained and self-consistent procedure. The methods are tested with quite different states of the small complexes HPs, e{sup +}He (electronic triplet) and e{sup +}Be (electronic singlet and triplet). For states yielding the positronium cluster, the annihilation rates are quite stable, irrespective of the accuracy in binding energies. For the e{sup +}Be states, annihilation rates are larger and more consistent with qualitative predictions than previously reported ones.

Molecular model for annihilation rates in positron complexes

International Nuclear Information System (INIS)

Assafrao, Denise; Walters, H.R. James; Mohallem, Jose R.

2008-01-01

The molecular approach for positron interaction with atoms is developed further. Potential energy curves for positron motion are obtained. Two procedures accounting for the nonadiabatic effective positron mass are introduced for calculating annihilation rate constants. The first one takes the bound-state energy eigenvalue as an input parameter. The second is a self-contained and self-consistent procedure. The methods are tested with quite different states of the small complexes HPs, e + He (electronic triplet) and e + Be (electronic singlet and triplet). For states yielding the positronium cluster, the annihilation rates are quite stable, irrespective of the accuracy in binding energies. For the e + Be states, annihilation rates are larger and more consistent with qualitative predictions than previously reported ones

Non-invasive imaging of acute renal allograft rejection in rats using small animal F-FDG-PET.

Directory of Open Access Journals (Sweden)

Stefan Reuter

Full Text Available BACKGROUND: At present, renal grafts are the most common solid organ transplants world-wide. Given the importance of renal transplantation and the limitation of available donor kidneys, detailed analysis of factors that affect transplant survival are important. Despite the introduction of new and effective immunosuppressive drugs, acute cellular graft rejection (AR is still a major risk for graft survival. Nowadays, AR can only be definitively by renal biopsy. However, biopsies carry a risk of renal transplant injury and loss. Most important, they can not be performed in patients taking anticoagulant drugs. METHODOLOGY/PRINCIPAL FINDINGS: We present a non-invasive, entirely image-based method to assess AR in an allogeneic rat renal transplantation model using small animal positron emission tomography (PET and (18F-fluorodeoxyglucose (FDG. 3 h after i.v. injection of 30 MBq FDG into adult uni-nephrectomized, allogeneically transplanted rats, tissue radioactivity of renal parenchyma was assessed in vivo by a small animal PET-scanner (post operative day (POD 1,2,4, and 7 and post mortem dissection. The mean radioactivity (cps/mm(3 tissue as well as the percent injected dose (%ID was compared between graft and native reference kidney. Results were confirmed by histological and autoradiographic analysis. Healthy rats, rats with acute CSA nephrotoxicity, with acute tubular necrosis, and syngeneically transplanted rats served as controls. FDG-uptake was significantly elevated only in allogeneic grafts from POD 1 on when compared to the native kidney (%ID graft POD 1: 0.54+/-0.06; POD 2: 0.58+/-0.12; POD 4: 0.81+/-0.06; POD 7: 0.77+/-0.1; CTR: 0.22+/-0.01, n = 3-28. Renal FDG-uptake in vivo correlated with the results obtained by micro-autoradiography and the degree of inflammatory infiltrates observed in histology. CONCLUSIONS/SIGNIFICANCE: We propose that graft FDG-PET imaging is a new option to non-invasively, specifically, early detect, and follow

Coded Aperture Nuclear Scintigraphy: A Novel Small Animal Imaging Technique

Directory of Open Access Journals (Sweden)

Dawid Schellingerhout

2002-10-01

Full Text Available We introduce and demonstrate the utility of coded aperture (CA nuclear scintigraphy for imaging small animals. CA imaging uses multiple pinholes in a carefully designed mask pattern, mounted on a conventional gamma camera. System performance was assessed using point sources and phantoms, while several animal experiments were performed to test the usefulness of the imaging system in vivo, with commonly used radiopharmaceuticals. The sensitivity of the CA system for 99mTc was 4.2 × 103 cps/Bq (9400 cpm/μCi, compared to 4.4 × 104 cps/Bq (990 cpm/μCi for a conventional collimator system. The system resolution was 1.7 mm, as compared to 4–6 mm for the conventional imaging system (using a high-sensitivity low-energy collimator. Animal imaging demonstrated artifact-free imaging with superior resolution and image quality compared to conventional collimator images in several mouse and rat models. We conclude that: (a CA imaging is a useful nuclear imaging technique for small animal imaging. The advantage in signal-to-noise can be traded to achieve higher resolution, decreased dose or reduced imaging time. (b CA imaging works best for images where activity is concentrated in small volumes; a low count outline may be better demonstrated using conventional collimator imaging. Thus, CA imaging should be viewed as a technique to complement rather than replace traditional nuclear imaging methods. (c CA hardware and software can be readily adapted to existing gamma cameras, making their implementation a relatively inexpensive retrofit to most systems.

UTIs in small animal patients: part 1: etiology and pathogenesis.

Science.gov (United States)

Smee, Nicole; Loyd, Kimberly; Grauer, Greg

2013-01-01

Understanding how urinary tract infections (UTIs) can occur and how to classify them can help the practitioner to make a plan for treatment. This review summarizes the etiology, pathogenesis, and host defense mechanisms associated with bacterial UTIs in dogs and cats. UTIs in Small Animal Patients: Part 2: Diagnosis, Treatment, and Complications will appear in the March/April 2013 issue of the Journal of the American Animal Hospital Association.

Accuracy and reproducibility of tumor positioning during prolonged and multi-modality animal imaging studies

International Nuclear Information System (INIS)

Zhang Mutian; Huang Minming; Le, Carl; Zanzonico, Pat B; Ling, C Clifton; Koutcher, Jason A; Humm, John L; Claus, Filip; Kolbert, Katherine S; Martin, Kyle

2008-01-01

Dedicated small-animal imaging devices, e.g. positron emission tomography (PET), computed tomography (CT) and magnetic resonance imaging (MRI) scanners, are being increasingly used for translational molecular imaging studies. The objective of this work was to determine the positional accuracy and precision with which tumors in situ can be reliably and reproducibly imaged on dedicated small-animal imaging equipment. We designed, fabricated and tested a custom rodent cradle with a stereotactic template to facilitate registration among image sets. To quantify tumor motion during our small-animal imaging protocols, 'gold standard' multi-modality point markers were inserted into tumor masses on the hind limbs of rats. Three types of imaging examination were then performed with the animals continuously anesthetized and immobilized: (i) consecutive microPET and MR images of tumor xenografts in which the animals remained in the same scanner for 2 h duration, (ii) multi-modality imaging studies in which the animals were transported between distant imaging devices and (iii) serial microPET scans in which the animals were repositioned in the same scanner for subsequent images. Our results showed that the animal tumor moved by less than 0.2-0.3 mm over a continuous 2 h microPET or MR imaging session. The process of transporting the animal between instruments introduced additional errors of ∼0.2 mm. In serial animal imaging studies, the positioning reproducibility within ∼0.8 mm could be obtained.

Monte Carlo simulation of small field electron beams for small animal irradiation

International Nuclear Information System (INIS)

Lee, Chung-Chi; Chen, Ai-Mei; Tung, Chuan-Jong; Chao, Tsi-Chian

2011-01-01

The volume effect of detectors in the dosimetry of small fields for photon beams has been well studied due to interests in radiosurgery and small beamlets used in IMRT treatments; but there is still an unexplored research field for small electron beams used in small animal irradiation. This study proposes to use the BEAM Monte Carlo (MC) simulation to assess characteristics of small electron beams (4, 6, 14, 30 mm in diameter) with the kinetic energies of 6 and 18 MeV. Three factors influencing beam characteristics were studied (1) AE and ECUT settings, (2) photon jaw settings and (3) simulation pixel sizes. Study results reveal that AE/ECUT settings at 0.7 MeV are adequate for linear accelerator treatment head simulation, while 0.521 MeV is more favorable to be used for the phantom study. It is also demonstrated that voxel size setting at 1/4 of the simulation field width in all directions is sufficient to achieve accurate results. As for the photon jaw setting, it has great impact on the absolute output of different field size setting (i.e. output factor) but with minimum effect on the relative lateral distribution.

Small-animal dark-field radiography for pulmonary emphysema evaluation

Science.gov (United States)

Yaroshenko, Andre; Meinel, Felix G.; Hellbach, Katharina; Bech, Martin; Velroyen, Astrid; Müller, Mark; Bamberg, Fabian; Nikolaou, Konstantin; Reiser, Maximilian F.; Yildirim, Ali Ã.-.; Eickelberg, Oliver; Pfeiffer, Franz

2014-03-01

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide and emphysema is one of its main components. The disorder is characterized by irreversible destruction of the alveolar walls and enlargement of distal airspaces. Despite the severe changes in the lung tissue morphology, conventional chest radiographs have only a limited sensitivity for the detection of mild to moderate emphysema. X-ray dark-field is an imaging modality that can significantly increase the visibility of lung tissue on radiographic images. The dark-field signal is generated by coherent, small-angle scattering of x-rays on the air-tissue interfaces in the lung. Therefore, morphological changes in the lung can be clearly visualized on dark-field images. This is demonstrated by a preclinical study with a small-animal emphysema model. To generate a murine model of pulmonary emphysema, a female C57BL/6N mouse was treated with a single orotracheal application of porcine pancreatic elastase (80 U/kg body weight) dissolved in phosphate-buffered saline (PBS). Control mouse received PBS. The mice were imaged using a small-animal dark-field scanner. While conventional x-ray transmission radiography images revealed only subtle indirect signs of the pulmonary disorder, the difference between healthy and emphysematous lungs could be clearly directly visualized on the dark-field images. The dose applied to the animals is compatible with longitudinal studies. The imaging results correlate well with histology. The results of this study reveal the high potential of dark-field radiography for clinical lung imaging.

Positron annihilation lifetime study of oxide dispersion strengthened steels

International Nuclear Information System (INIS)

Krsjak, V.; Szaraz, Z.; Hähner, P.

2012-01-01

A comparative positron annihilation lifetime study has been performed on various commercial ferritic and ferritic/martensitic oxide dispersion strengthened (ODS) steels. Both as-extruded and recrystallized materials were investigated. In the materials with recrystallized coarse-grained microstructures, only the positron trapping at small vacancy clusters and yttria nanofeatures was observed. Materials which had not undergone recrystallization treatment clearly showed additional positron trapping which is associated with dislocations. Dislocation densities were calculated from a two-component decomposition of the positron lifetime spectra by assuming the first component to be a superposition of the bulk controlled annihilation rate and the dislocation controlled trapping rate. The second component (which translates into lifetimes of 240–260 ps) was found to be well separated in all those ODS materials. This paper presents the potentialities and limitations of the positron annihilation lifetime spectroscopy, and discusses the results of the experimental determination of the defect concentrations and sensitivity of this technique to the material degradation due to thermally induced precipitation of chromium-rich α′ phases.

LIL-W: Positron conversion target and solenoid (pictures 01 and 04).

CERN Multimedia

Laurent Guiraud

1997-01-01

In the direction of the beam, from right to left: a steering dipole (DHZ.25); the arm, at 45 deg, of a wire scanner which measures beam size; the conversion target, housed in the small tank with a window, where positrons are produced; immediately afterwards, invisible inside the vacuum chamber, is a pulsed solenoid to focus the emerging positrons; finally, a large solenoid, consisting of 3 pancakes, further focuses the positrons. Towards the left, the linac LIL-W, its accelerating structure hidden under a continuous outer solenoid mantle.

Performance evaluation of a mouse-sized camera for dynamic studies in small animals

International Nuclear Information System (INIS)

Loudos, George; Majewski, Stan; Wojcik, Randy; Weisenberger, Andrew; Sakellios, Nicolas; Nikita, Konstantina; Uzunoglu, Nikolaos; Bouziotis, Penelope; Varvarigou, Alexandra

2007-01-01

A mouse sized camera has been built in terms of collaboration between the presenting institutions. The system is used for the performance of dynamic studies in small animals, in order to evaluate novel radiopharmaceuticals. The active area of the detector is approximately 48x96 mm allowing depiction of the entire mouse in a single view. The system is based on two flat-panel Hamamatsu H8500 position sensitive photomultiplier tubes (PSPMT), a pixellated NaI(Tl) scintillator and a copper-beryllium (CuBe) parallel-hole collimator. In this work, the evaluation results of the system are presented, using phantoms and small animals injected with conventional radiophrmaceuticals. Average resolution was ∼1.6 mm on the collimator surface and increased to ∼4.1 mm in 12 cm distance from the detector. The average energy resolution was measured and found to be ∼15.6% for Tc 99m . Results from imaging thin capillaries demonstrated system's high resolution and sensitivity in activity variations was shown. Initial dynamic studies have been carried out in small animals injected with Tc 99m -DTPA and Tc 99m -MDP. The results show system's ability to perform kinetic imaging in small animals

Development of Optical Molecular Imaging System for the Acquisition of Bioluminescence Signals from Small Animals

International Nuclear Information System (INIS)

Lee, Byeong Il; Kim, Hyeon Sik; Jeong, Hye Jin; Lee, Hyung Jae; Moon, Seung Min; Kwon, Seung Young; Jeong, Shin Young; Bom, Hee Seung; Min, Jung Joon; Choi, Eun Seo

2009-01-01

Optical imaging is providing great advance and improvement in genetic and molecular imaging of animals and humans. Optical imaging system consists of optical imaging devices, which carry out major function for monitoring, tracing, and imaging in most of molecular in-vivo researches. In bio-luminescent imaging, small animals containing luciferase gene locally irradiate light, and emitted photons transmitted through skin of the small animals are imaged by using a high sensitive charged coupled device (CCD) camera. In this paper, we introduced optical imaging system for the image acquisition of bio-luminescent signals emitted from small animals. In the system, Nikon lens and four LED light sources were mounted at the inside of a dark box. A cooled CCD camera equipped with a control module was used. We tested the performance of the optical imaging system using effendorf tube and light emitting bacteria which injected intravenously into CT26 tumor bearing nude mouse. The performance of implemented optical imaging system for bio-luminescence imaging was demonstrated and the feasibility of the system in small animal imaging application was proved. We anticipate this system could be a useful tool for the molecular imaging of small animals adaptable for various experimental conditions in future

New Developments in Positron Scintigraphy and the Application of Cyclotron-Produced Positron Emitters

Energy Technology Data Exchange (ETDEWEB)

Brownell, G. L.; Burnham, C. A.; Wilensky, S.; Aronow, S.; Kazemi, H.; Strieder, D. [Massachusetts General Hospital. Boston, MA (United States)

1969-01-15

The use of positron-emitting radioisotopes offers unique advantages inscintigraphy and dynamic function studies. The detection of the two annihilation quanta provides, in principle, the possibility of utilization of all the positron annihilations with good resolution. In practice, very high efficiencies can be achieved with large area annihilation quanta detectors. The use of multi-detector matrices as large area detectors permits high levels o f activity and yields very high data acquisition rates. The independence of attenuation with depth of a source offers marked advantages for quantitative measurement. The use of time-of-flight techniques opens the possibility of true three-dimensional visualization. Finally, a number of very short-lived positron emitting radioisotopes such as {sup 15}O, {sup 19}N and {sup 11}C are available. A hybrid positron scanner has been constructed and is undergoing tests for brain tumour localization using {sup 74}As. The scanner uses two rows of detectors each containing 9 Nal scintillators and phototubes. The detector array moves continuously in the horizontal direction and in steps in the vertical direction, producing a scintigram with no line structure. The data is recorded on tape for replay or for computer processing. In either case, the plane of best focus can be positioned at will. The techniques developed for the hybrid scanner will be used in a stationary device employing two two-dimensional arrays of detectors. The design will emphasize the very rapid collection of data and the sequential production of scintigrams. The advantages and techniques of positron annihilation detection are also applicable to devices for study of dynamic function. We have constructed and are testing a fast six-detector coincidence system for pulmonary function studies. The measurement of time-of-flight offers the possibility of three-dimensional visualization of a distribution of positron-emitting radioisotope. We a re studying systems with

[Application of paramunity inducers in small animal practice].

Science.gov (United States)

Proksch, A L; Hartmann, K

2016-01-01

Paramunity inducers have been used to treat small animals for decades. Paramunity inducers are based on attenuated and inactivated poxviruses (avipox virus and parapox virus). Their applications include both therapeutic and prophylactic use in various diseases. Despite their wide and variable use, only a very small number of placebo-controlled studies has been published. Positive effects in preventing kitten mortality and in treating feline stomatitis have been reported, however, no statistically significant effect of their therapeutic use in canine parvovirus infection, feline leukemia infection virus infection or canine papillomavirus infection could be demonstrated. For these infectious diseases, paramunity inducers do not appear to be effective.

Development of an Electron-Positron Source for Positron Annihilation Lifetime Spectroscopy

Science.gov (United States)

2009-12-19

REPORT Development of an electron- positron source for positron annihilation lifetime spectroscopy : FINAL REPORT 14. ABSTRACT 16. SECURITY...to generate radiation, to accelerate particles, and to produce electrons and positrons from vacuum. From applications using existing high-repetition...theoretical directions. This report reviews work directed toward the application of positron generation from laser interaction with matter 1. REPORT DATE

Recommendations on vaccination for Asian small animal practitioners: a report of the WSAVA Vaccination Guidelines Group.

Science.gov (United States)

Day, M J; Karkare, U; Schultz, R D; Squires, R; Tsujimoto, H

2015-02-01

In 2012 and 2013, the World Small Animal Veterinary Association (WSAVA) Vaccination Guidelines Group (VGG) undertook fact-finding visits to several Asian countries, with a view to developing advice for small companion animal practitioners in Asia related to the administration of vaccines to dogs and cats. The VGG met with numerous first opinion practitioners, small animal association leaders, academic veterinarians, government regulators and industry representatives and gathered further information from a survey of almost 700 veterinarians in India, China, Japan and Thailand. Although there were substantial differences in the nature and magnitude of the challenges faced by veterinarians in each country, and also differences in the resources available to meet those challenges, overall, the VGG identified insufficient undergraduate and postgraduate training in small companion animal microbiology, immunology and vaccinology. In most of the countries, there has been little academic research into small animal infectious diseases. This, coupled with insufficient laboratory diagnostic support, has limited the growth of knowledge concerning the prevalence and circulating strains of key infectious agents in most of the countries visited. Asian practitioners continue to recognise clinical infections that are now considered uncommon or rare in western countries. In particular, canine rabies virus infection poses a continuing threat to animal and human health in this region. Both nationally manufactured and international dog and cat vaccines are variably available in the Asian countries, but the product ranges are small and dominated by multi-component vaccines with a licensed duration of immunity (DOI) of only 1 year, or no description of DOI. Asian practitioners are largely unaware of current global trends in small animal vaccinology or of the WSAVA vaccination guidelines. Consequently, most practitioners continue to deliver annual revaccination with both core and non

A coupled channel study on a binding mechanism of positronic alkali atoms

International Nuclear Information System (INIS)

Kubota, Yoshihiro; Kino, Yasushi

2008-01-01

In order to investigate the binding mechanism of weakly bound states of positronic alkali atoms, we calculate the energies and wavefunctions using the Gaussian expansion method (GEM) where a positronium (Ps)-alkali ion channel and a positron-alkali atom channel are explicitly introduced. The energies of the bound states are updated using a model potential that reproduces well the observed energy levels of alkali atoms. The binding mechanism of the positronic alkali atom is analyzed by the wavefunctions obtained. The structure of the positronic alkali atom has been regarded as a Ps cluster orbiting the alkali ion, which is described by the Ps-alkali ion channel. We point out that the fraction having the positron-alkali atom configuration is small but plays an indispensable role for the weakly bound system

Carriage of methicillin-resistant Staphylococcus pseudintermedius in small animal veterinarians

DEFF Research Database (Denmark)

Paul, Narayan Chandra; Moodley, Arshnee; Ghibaudo, G.

2011-01-01

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is increasingly reported in small animals and cases of human infections have already been described despite its recent emergence in veterinary practice. We investigated the prevalence of MRSP and methicillin-resistant Staphylococcus...... aureus (MRSA) among small animal dermatologists attending a national veterinary conference in Italy. Nasal swabs were obtained from 128 veterinarians, seven of which harboured MRSP (n = 5; 3.9%) or MRSA (n = 2; 1.6%). A follow-up study of two carriers revealed that MRSP persisted for at least 1 month...... by spa typing. Methicillin-resistant isolates were further typed by antimicrobial susceptibility testing, SCCmec and multi-locus sequence typing. Two lineages previously associated with pets were identified among the five MRSP isolates; the European epidemic clone ST71-SCCmec II-III and ST106-SCCmec IV...

Multi-institutional MicroCT image comparison of image-guided small animal irradiators

Science.gov (United States)

Johnstone, Chris D.; Lindsay, Patricia; E Graves, Edward; Wong, Eugene; Perez, Jessica R.; Poirier, Yannick; Ben-Bouchta, Youssef; Kanesalingam, Thilakshan; Chen, Haijian; E Rubinstein, Ashley; Sheng, Ke; Bazalova-Carter, Magdalena

2017-07-01

To recommend imaging protocols and establish tolerance levels for microCT image quality assurance (QA) performed on conformal image-guided small animal irradiators. A fully automated QA software SAPA (small animal phantom analyzer) for image analysis of the commercial Shelley micro-CT MCTP 610 phantom was developed, in which quantitative analyses of CT number linearity, signal-to-noise ratio (SNR), uniformity and noise, geometric accuracy, spatial resolution by means of modulation transfer function (MTF), and CT contrast were performed. Phantom microCT scans from eleven institutions acquired with four image-guided small animal irradiator units (including the commercial PXi X-RAD SmART and Xstrahl SARRP systems) with varying parameters used for routine small animal imaging were analyzed. Multi-institutional data sets were compared using SAPA, based on which tolerance levels for each QA test were established and imaging protocols for QA were recommended. By analyzing microCT data from 11 institutions, we established image QA tolerance levels for all image quality tests. CT number linearity set to R 2  >  0.990 was acceptable in microCT data acquired at all but three institutions. Acceptable SNR  >  36 and noise levels  1.5 lp mm-1 for MTF  =  0.2) was obtained at all but four institutions due to their large image voxel size used (>0.275 mm). Ten of the eleven institutions passed the set QA tolerance for geometric accuracy (2000 HU for 30 mgI ml-1). We recommend performing imaging QA with 70 kVp, 1.5 mA, 120 s imaging time, 0.20 mm voxel size, and a frame rate of 5 fps for the PXi X-RAD SmART. For the Xstrahl SARRP, we recommend using 60 kVp, 1.0 mA, 240 s imaging time, 0.20 mm voxel size, and 6 fps. These imaging protocols should result in high quality images that pass the set tolerance levels on all systems. Average SAPA computation time for complete QA analysis for a 0.20 mm voxel, 400 slice Shelley phantom microCT data set

Positron deep-level transient spectroscopy in semi-insulating-GaAs using the positron velocity transient method

International Nuclear Information System (INIS)

Tsia, M.; Fung, S.; Beling, C.D.

2001-01-01

Recently a new semiconductor defect spectroscopy, namely positron deep level transient spectroscopy (PDLTS) has been proposed that combines the energy selectivity of deep level transient spectroscopy with the structural sensitivity of positron annihilation spectroscopy. This paper focuses on one variant of PDLTS, namely positron velocity PDLTS, which has no sensitivity towards vacancy defects but nevertheless is useful in studying deep levels in semi-insulators. In the present study the electric field within the depletion region of semi-insulating GaAs is monitored through the measurement of the small Doppler shift in the annihilation radiation that comes from this region as a result of positron drift. The drift is the result of an increasing electric field produced by space charge building up from ionizing deep level defects. Doppler shift transients are measured between 50-300 K. The EL2 level emission transients are clearly seen at temperatures around 300 K that yield E C -0.78±0.08eV for the energy of EL2. The EL2 electron capture rate is found to have an activation energy of 0.61±0.08eV which most probably arises from freeze out of conduction electrons. We find the surprising result that emission and capture transients can be seen at temperatures below 200 K. Possible reasons for these transients are discussed. (orig.)

Computer-aided pulmonary image analysis in small animal models

Energy Technology Data Exchange (ETDEWEB)

Xu, Ziyue; Mansoor, Awais; Mollura, Daniel J. [Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, Maryland 32892 (United States); Bagci, Ulas, E-mail: ulasbagci@gmail.com [Center for Research in Computer Vision (CRCV), University of Central Florida (UCF), Orlando, Florida 32816 (United States); Kramer-Marek, Gabriela [The Institute of Cancer Research, London SW7 3RP (United Kingdom); Luna, Brian [Microfluidic Laboratory Automation, University of California-Irvine, Irvine, California 92697-2715 (United States); Kubler, Andre [Department of Medicine, Imperial College London, London SW7 2AZ (United Kingdom); Dey, Bappaditya; Jain, Sanjay [Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 (United States); Foster, Brent [Department of Biomedical Engineering, University of California-Davis, Davis, California 95817 (United States); Papadakis, Georgios Z. [Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, Maryland 32892 (United States); Camp, Jeremy V. [Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky 40202 (United States); Jonsson, Colleen B. [National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, Tennessee 37996 (United States); Bishai, William R. [Howard Hughes Medical Institute, Chevy Chase, Maryland 20815 and Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 (United States); Udupa, Jayaram K. [Medical Image Processing Group, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2015-07-15

Purpose: To develop an automated pulmonary image analysis framework for infectious lung diseases in small animal models. Methods: The authors describe a novel pathological lung and airway segmentation method for small animals. The proposed framework includes identification of abnormal imaging patterns pertaining to infectious lung diseases. First, the authors’ system estimates an expected lung volume by utilizing a regression function between total lung capacity and approximated rib cage volume. A significant difference between the expected lung volume and the initial lung segmentation indicates the presence of severe pathology, and invokes a machine learning based abnormal imaging pattern detection system next. The final stage of the proposed framework is the automatic extraction of airway tree for which new affinity relationships within the fuzzy connectedness image segmentation framework are proposed by combining Hessian and gray-scale morphological reconstruction filters. Results: 133 CT scans were collected from four different studies encompassing a wide spectrum of pulmonary abnormalities pertaining to two commonly used small animal models (ferret and rabbit). Sensitivity and specificity were greater than 90% for pathological lung segmentation (average dice similarity coefficient > 0.9). While qualitative visual assessments of airway tree extraction were performed by the participating expert radiologists, for quantitative evaluation the authors validated the proposed airway extraction method by using publicly available EXACT’09 data set. Conclusions: The authors developed a comprehensive computer-aided pulmonary image analysis framework for preclinical research applications. The proposed framework consists of automatic pathological lung segmentation and accurate airway tree extraction. The framework has high sensitivity and specificity; therefore, it can contribute advances in preclinical research in pulmonary diseases.

Small-Animal Imaging Using Diffuse Fluorescence Tomography.

Science.gov (United States)

Davis, Scott C; Tichauer, Kenneth M

2016-01-01

Diffuse fluorescence tomography (DFT) has been developed to image the spatial distribution of fluorescence-tagged tracers in living tissue. This capability facilitates the recovery of any number of functional parameters, including enzymatic activity, receptor density, blood flow, and gene expression. However, deploying DFT effectively is complex and often requires years of know-how, especially for newer mutlimodal systems that combine DFT with conventional imaging systems. In this chapter, we step through the process of using MRI-DFT imaging of a receptor-targeted tracer in small animals.

Comparison SPECT-CT with PET-CT in several applications of small-animal models

International Nuclear Information System (INIS)

Pan Yifan; Song Shaoli; Huang Gang

2009-01-01

With the development of medical science, monitoring dynamic biologic processes in small-animal models of diseases has become one of the most important approaches in medical studies. Important physiologic parameters that traditionally have been characterized by nuclear medicine imaging include blood flow, biochemical metabolism, and cellular receptors. Recently, nuclear medicine has been greatly facilitated by the newer development of dual-modality integrated imaging systems (SPECT-CT and PET-CT), which provide functional and anatomical images in the same scanning session, with the acquired images co-registered by means of the hardware. The purpose of this review is to compare SPECT-CT with PET-CT in several applications of small-animal models. Conclusicn: PET-CT for small animal modes in nledical research in the applications has great advantages, but SPECT-CT is still a very important role, and research low cost. (authors)

Positron annihilation lifetime study of low temperature irradiated metals

Energy Technology Data Exchange (ETDEWEB)

Kuramoto, Eiichi [Kyushu Univ., Kasuga, Fukuoka (Japan). Research Inst. for Applied Mechanics

1997-11-01

Positron annihilation lifetime measurements have been made for electron and neutron irradiated Fe, Fe-Cr, Fe-Cu, Fe-Si, Fe-16Cr-17Ni specimens, and isochronal annealing behaviors were obtained for these metals and alloys. It was found that vacancies start to migrate at about 200 K in Fe and form microvoids, but by the addition of small amount of alloying elements this behavior was changed depending on the alloying elements. Positron lifetime calculations were made to explain the experimental results using EAM (embedded atom method) type potential for the lattice relaxation and the atomic superposition method for the lifetime calculation. Fairly good agreements were obtained for the positron lifetime in a vacancy in Fe and other alloys. (author)

Prototype design of singles processing unit for the small animal PET

Science.gov (United States)

Deng, P.; Zhao, L.; Lu, J.; Li, B.; Dong, R.; Liu, S.; An, Q.

2018-05-01

Position Emission Tomography (PET) is an advanced clinical diagnostic imaging technique for nuclear medicine. Small animal PET is increasingly used for studying the animal model of disease, new drugs and new therapies. A prototype of Singles Processing Unit (SPU) for a small animal PET system was designed to obtain the time, energy, and position information. The energy and position is actually calculated through high precison charge measurement, which is based on amplification, shaping, A/D conversion and area calculation in digital signal processing domian. Analysis and simulations were also conducted to optimize the key parameters in system design. Initial tests indicate that the charge and time precision is better than 3‰ FWHM and 350 ps FWHM respectively, while the position resolution is better than 3.5‰ FWHM. Commination tests of the SPU prototype with the PET detector indicate that the system time precision is better than 2.5 ns, while the flood map and energy spectra concored well with the expected.

GePEToS: A Geant4 Monte Carlo simulation package for positron emission tomography

International Nuclear Information System (INIS)

Jan, Sebastien; Collot, Johann; Gallin-Martel, Marie-Laure; Martin, Philippe; Mayet, Frederic; Tournefier, Edwige

2003-01-01

GePEToS is a simulation framework developed over the last few years for assessing the instrumental performance of future PET scanners. It is based on Geant4, written in Object- Oriented C++ and runs on Linux platforms. The validity of GePEToS has been tested on the well-known Siemens ECAT EXACT HR+ camera. The results of two application examples are presented: the design optimization of a liquid Xe μPET camera dedicated to small animal imaging as well as the evaluation of the effect of a strong axial magnetic field on the image resolution of a Concorde P4 μPET camera. Index Terms-Positron Emission Tomography, Monte Carlo Simulation, Geant 4. (authors)

Blended learning in the small animal clinic

DEFF Research Database (Denmark)

Langebæk, Rikke

2011-01-01

At the Department of Small Animal Clinical Sciences, Basic Surgical Skills are taught in groups of 30-35 students in the first year of the master program (4th year students). The eight day course is an example of ‘blended learning’ in which students use our e-learning-material (Step 1) to prepare...... for the practical part of the course (Step 2, 3 and 4). From their home computers, students log on to the e-learning platform of Copenhagen University: https://absalon.ku.dk and go to the Basic Surgical Skills course, which consist of a line of chapters concerning a variety of surgical subjects. Each subject...... the implementation of these new teaching methods (e-learning and Skills Lab), teachers have ascertained a more satisfactory level of preparation, students that seem more focused and live-animal surgery that is conducted at a more ‘professional’ level than before. Finally, our research in this field shows...

Current concepts in oncologic surgery in small animals.

Science.gov (United States)

Matz, Brad M

2015-05-01

Surgical oncology is experiencing rapid transition in veterinary medicine. Mast cell tumors and soft tissue sarcomas are two of the most common neoplasms in small animal patients. Clinicians should be familiar with the need for staging and the procedures involved in treating patients with these tumors. Clinicians should be comfortable with available adjuvant therapies and when to use them in certain patients. Copyright © 2015 Elsevier Inc. All rights reserved.

Scalable Electrophysiology in Intact Small Animals with Nanoscale Suspended Electrode Arrays

OpenAIRE

Gonzales, Daniel L.; Badhiwala, Krishna N.; Vercosa, Daniel G.; Avants, Ben W.; Liu, Zheng; Zhong, Weiwei; Robinson, Jacob T.

2017-01-01

Electrical measurements from large populations of animals would help reveal fundamental properties of the nervous system and neurological diseases. Small invertebrates are ideal for these large-scale studies; however, patch-clamp electrophysiology in microscopic animals typically requires low-throughput and invasive dissections. To overcome these limitations, we present nano-SPEARs: suspended electrodes integrated into a scalable microfluidic device. Using this technology, we have made the fi...

Investigation of positron moderator materials for electron-linac-based slow positron beamlines

International Nuclear Information System (INIS)

Suzuki, Ryoichi; Ohdaira, Toshiyuki; Uedono, Akira

1998-01-01

Positron re-emission properties were studied on moderator materials in order to improve the positron moderation system of electron-linac-based intense slow positron beamlines. The re-emitted positron fraction was measured on tungsten, SiC, GaN, SrTiO 3 , and hydrogen-terminated Si with a variable-energy pulsed positron beam. The results suggested that tungsten is the best material for the primary moderator of the positron beamlines while epitaxially grown n-type 6H-SiC is the best material for the secondary moderator. Defect characterization by monoenergetic positron beams and surface characterization by Auger electron spectroscopy were carried out to clarify the mechanism of tungsten moderator degradation induced by high-energy electron irradiation. The characterization experiments revealed that the degradation is due to both radiation-induced vacancy clusters and surface carbon impurities. For the restoration of degraded tungsten moderators, oxygen treatment at ∼900degC is effective. Furthermore, it was found that oxygen at the tungsten surface inhibits positronium formation; as a result, it can increase the positron re-emission fraction. (author)

Partial body irradiation of small laboratory animals with an industrial X-ray tube

International Nuclear Information System (INIS)

Frenzel, Thorsten; Kruell, Andreas; Grohmann, Carsten; Schumacher, Udo

2014-01-01

Dedicated precise small laboratory animal irradiation sources are needed for basic cancer research and to meet this need expensive high precision radiation devices have been developed. To avoid such expenses a cost efficient way is presented to construct a device for partial body irradiation of small laboratory animals by adding specific components to an industrial X-ray tube. A custom made radiation field tube was added to an industrial 200 kV X-ray tube. A light field display as well as a monitor ionization chamber were implemented. The field size can rapidly be changed by individual inserts of MCP96 that are used for secondary collimation of the beam. Depth dose curves and cross sectional profiles were determined with the use of a custom made water phantom. More components like positioning lasers, a custom made treatment couch, and a commercial isoflurane anesthesia unit were added to complete the system. With the accessories described secondary small field sizes down to 10 by 10 mm 2 (secondary collimator size) could be achieved. The dosimetry of the beam was constructed like those for conventional stereotactical clinical linear accelerators. The water phantom created showed an accuracy of 1 mm and was well suited for all measurements. With the anesthesia unit attached to the custom made treatment couch the system is ideal for the radiation treatment of small laboratory animals like mice. It was feasible to shrink the field size of an industrial X-ray tube from whole animal irradiation to precise partial body irradiation of small laboratory animals. Even smaller secondary collimator sizes than 10 by 10 mm 2 are feasible with adequate secondary collimator inserts. Our custom made water phantom was well suited for the basic dosimetry of the X-ray tube.

State of the art in both in vitro and in vivo aspects of small animal imaging

International Nuclear Information System (INIS)

Maziere, B.; Lebars, D.

2002-01-01

Full text: In vivo imaging for small animals is dramatically expanding due to the coincidence of mainly three technical factors: 1. the explosion in computer power 2. the enhancement in image processing 3. the accessibility and affordability of digital autoradiography systems and small-animal scanners. Among these imaging techniques let us mention the anatomical imaging techniques such as ultrasonography, X-rays and IRM and the functional imaging radioisotopic techniques SPECT and TEP. The main advantage of the first group of imaging techniques is essentially linked to the high resolution of the anatomical images (with the drawback of the necessity of putting the animal at rest using anaesthesia). The main advantages of SPECT and PET are their high sensitivity and the vast number of functions or metabolism they allow to image. The applications for isotopic functional imaging in small animals are increasing rapidly. Factors contributing to this dramatic expansion include the three previous technical factors plus, at least, three methodological factors: 1. the drug discovery process based on receptor / mechanism of action 2. the increasing number of rodent models of human diseases (SCID mice implanted with human tumors, gene knock-out mice, transgene mice) 3. the advances in isotope and validated tracer availability performances Small animal radioisotopic functional imaging for drug development. In vivo quantification of biological processes to measure the mechanism of action of a potential drug and its concentration at the site of action has become mandatory for developing a drug. Rational and efficient means of confirming mechanisms of action are required. For this purpose, PET and/or SPECT functional - biochemical - molecular imaging in small animals are tools of choice for economical reasons (in the domain of drug development, industry is suffering huge opportunity costs by failing to weed out non-performing new active substances until late phases II and III) and

Study and development of a high resolution tomograph for the γ radio-imagery in vivo of small animals

International Nuclear Information System (INIS)

Valda Ochoa, A.

1995-01-01

By the use of molecular radio-labelled tracers, molecular biology can reveal some aspects of the functional organisation of the brain. Non invasive in vivo brain research on small laboratory animals, like mice or rats, require analysis of structures of some cubic millimeters present in a brain of the order of a cubic centimeter. Since imaging performances of positron emission tomography (PET) and single photon emission tomography (SPECT) fail in this research field, we present here a high resolution tomograph (TOHR) based on an original principle that allows to overcome the compromise between detection efficiency and spatial resolution. TOHR is a radiation counter device having a large solid angle focusing collimator. By the use of radio-tracers decaying by a cascade of two photons, coincidence detection offers an accurate delimitation of the analysed region and improves spatial resolution. TOHR acts as a scanner, so the image is built voxel by voxel by moving the animal relative to the detector. A numerical feasibility study of such a system shows that a sub millimeter spatial resolution can be achieved. We show that the chemical etching technique is well suited for manufacturing a multi-module focusing collimator by building and testing two such modules. Finally a numerical simulation exhibits TOHR's performance in a neuro-pharmacological experiment on a rat. From these results, other application of TOHR are envisaged, such as oncology (in vivo evolution of tumours) or gene therapy (distribution of viral particles in the brain). (author). 51 refs., 73 figs., 3 tabs

Development of positron emitting radionuclides for imaging with improved positron detectors. [/sup 82/Rb, /sup 62/Zn, /sup 64/Cu, /sup 67/Ga

Energy Technology Data Exchange (ETDEWEB)

Yano, Y.

1976-10-01

Recent advances in positron cameras and positron ring detectors for transverse section reconstruction have created renewed interest in positron emitting radionuclides. This paper reports on: generator-produced /sup 82/Rb; cyclotron-produced /sup 62/Zn; and reactor-produced /sup 64/Cu. Investigation of the /sup 82/Sr (25 d)--/sup 82/Rb (75 s) generator determined the elution characteristics for Bio-Rex 70, a weakly acidic carboxylic cation exchanger, using 2% NaCl as the eluent. The yield of /sup 82/Rb and the breakthrough of /sup 82/Sr were determined for newly prepared columns and for long term elution conditions. Spallation-produced /sup 82/Sr was used to charge a compact /sup 82/Rb generator to obtain multi-millicurie amounts of /sup 82/Rb for myocardial imaging. Zinc accumulates in the islet cells of the pancreas and in the prostate. Zinc-62 was produced by protons on Cu foil and separated by column chromatography. Zinc-62 was administered as the amino acid chelates and as the ZnCl/sub 2/ to tumor and normal animals. Tissue distribution was determined for various times after intravenous injection. Pancreas-liver images of /sup 62/Zn-histidine uptake were obtained in animals with the gamma camera and the liver uptake of /sup 99m/Tc sulfur colloid was computer subtracted to image the pancreas alone. The positron camera imaged uptake of /sup 62/Zn-histidine in the prostate of a dog at 20 h. /sup 64/Cu was chelated to asparagine, a requirement of leukemic cells, and administered to lymphoma mice. Uptake in tumor and various tissues was determined and compared with the uptake of /sup 67/Ga citrate under the same conditions. /sup 64/Cu-asparagine had better tumor-to-soft tissue ratios than /sup 67/Ga-citrate.

Positron astrophysics and areas of relation to low-energy positron physics

Science.gov (United States)

Guessoum, Nidhal

2014-05-01

I briefly review our general knowledge of positron astrophysics, focusing mostly on the theoretical and modelling aspects. The experimental/observational aspects of the topic have recently been reviewed elsewhere [E. Churazov et al., Mon. Nat. R. Astron. Soc. 411, 1727 (2011); N. Prantazos et al., Rev. Mod. Phys. 83, 1001 (2011)]. In particular, I highlight the interactions and cross sections of the reactions that the positrons undergo in various cosmic media. Indeed, these must be of high interest to both the positron astrophysics community and the low-energy positron physics community in trying to find common areas of potential collaboration for the future or areas of research that will help the astrophysics community make further progress on the problem. The processes undergone by positrons from the moments of their birth to their annihilation (in the interstellar medium or other locations) are thus examined. The physics of the positron interactions with gases and solids (dust grains) and the physical conditions and characteristics of the environments where the processes of energy loss, positronium formation, and annihilation take place, are briefly reviewed. An explanation is given about how all the relevant physical information is taken into account in order to calculate annihilation rates and spectra of the 511 keV emission in the ISM; special attention is paid to positron interactions with dust and with polycyclic aromatic hydrocarbons. In particular, an attempt is made to show to what extent the interactions between positrons and interstellar dust grains are similar to laboratory experiments in which beams of low-energy positrons impinge upon solids and surfaces. Sample results are shown for the effect of dust grains on positron annihilation spectra in some phases of the ISM which, together with high resolution spectra measured by satellites, can be used to infer useful knowledge about the environment where the annihilation is predominantly taking place

Comparison of Diagnostic Performance of Three-Dimensional Positron Emission Mammography versus Whole Body Positron Emission Tomography in Breast Cancer

Directory of Open Access Journals (Sweden)

Dong Dai

2017-01-01

Full Text Available Objective. To compare the diagnostic performance of three-dimensional (3D positron emission mammography (PEM versus whole body positron emission tomography (WBPET for breast cancer. Methods. A total of 410 women with normal breast or benign or highly suspicious malignant tumors were randomized at 1 : 1 ratio to undergo 3D-PEM followed by WBPET or WBPET followed by 3D-PEM. Lumpectomy or mastectomy was performed on eligible participants after the scanning. Results. The sensitivity and specificity of 3D-PEM were 92.8% and 54.5%, respectively. WBPET showed a sensitivity of 95.7% and specificity of 56.8%. After exclusion of the patients with lesions beyond the detecting range of the 3D-PEM instrument, 3D-PEM showed higher sensitivity than WBPET (97.0% versus 95.5%, P = 0.913, particularly for small lesions (<1 cm (72.0% versus 60.0%, P = 0.685. Conclusions. The 3D-PEM appears more sensitive to small lesions than WBPET but may fail to detect lesions that are beyond the detecting range. This study was approved by the Ethics Committee (E2012052 at the Tianjin Medical University Cancer Institute and Hospital (Tianjin, China. The instrument positron emission mammography (PEMi was approved by China State Food and Drug Administration under the registration number 20153331166.

Positron-atom collisions

International Nuclear Information System (INIS)

Drachman, R.J.

1984-01-01

The past decade has seen the field of positron-atom collisions mature into an important sub-field of atomic physics. Increasingly intense positron sources are leading towards a situation in which electron and positron collision experiments will be on almost an equal footing, challenging theory to analyze their similarities and differences. The author reviews the advances made in theory, including dispersion theory, resonances, and inelastic processes. A survey of experimental progress and a brief discussion of astrophysical positronics is also included. (Auth.)

Positron astrophysics and areas of relation to low-energy positron physics

International Nuclear Information System (INIS)

Guessoum, N.

2014-01-01

I briefly review our general knowledge of positron astrophysics, focusing mostly on the theoretical and modelling aspects. The experimental/observational aspects of the topic have recently been reviewed elsewhere [E. Churazov et al., Mon. Nat. R. Astron. Soc. 411, 1727 (2011); N. Prantazos et al., Rev. Mod. Phys. 83, 1001 (2011)]. In particular, I highlight the interactions and cross sections of the reactions that the positrons undergo in various cosmic media. Indeed, these must be of high interest to both the positron astrophysics community and the low-energy positron physics community in trying to find common areas of potential collaboration for the future or areas of research that will help the astrophysics community make further progress on the problem. The processes undergone by positrons from the moments of their birth to their annihilation (in the interstellar medium or other locations) are thus examined. The physics of the positron interactions with gases and solids (dust grains) and the physical conditions and characteristics of the environments where the processes of energy loss, positronium formation, and annihilation take place, are briefly reviewed. An explanation is given about how all the relevant physical information is taken into account in order to calculate annihilation rates and spectra of the 511 keV emission in the ISM; special attention is paid to positron interactions with dust and with polycyclic aromatic hydrocarbons. In particular, an attempt is made to show to what extent the interactions between positrons and interstellar dust grains are similar to laboratory experiments in which beams of low-energy positrons impinge upon solids and surfaces. Sample results are shown for the effect of dust grains on positron annihilation spectra in some phases of the ISM which, together with high resolution spectra measured by satellites, can be used to infer useful knowledge about the environment where the annihilation is predominantly taking place

Plasma Wakefield Acceleration of an Intense Positron Beam

Energy Technology Data Exchange (ETDEWEB)

Blue, B

2004-04-21

The Plasma Wakefield Accelerator (PWFA) is an advanced accelerator concept which possess a high acceleration gradient and a long interaction length for accelerating both electrons and positrons. Although electron beam-plasma interactions have been extensively studied in connection with the PWFA, very little work has been done with respect to positron beam-plasma interactions. This dissertation addresses three issues relating to a positron beam driven plasma wakefield accelerator. These issues are (a) the suitability of employing a positron drive bunch to excite a wake; (b) the transverse stability of the drive bunch; and (c) the acceleration of positrons by the plasma wake that is driven by a positron bunch. These three issues are explored first through computer simulations and then through experiments. First, a theory is developed on the impulse response of plasma to a short drive beam which is valid for small perturbations to the plasma density. This is followed up with several particle-in-cell (PIC) simulations which study the experimental parameter (bunch length, charge, radius, and plasma density) range. Next, the experimental setup is described with an emphasis on the equipment used to measure the longitudinal energy variations of the positron beam. Then, the transverse dynamics of a positron beam in a plasma are described. Special attention is given to the way focusing, defocusing, and a tilted beam would appear to be energy variations as viewed on our diagnostics. Finally, the energy dynamics imparted on a 730 {micro}m long, 40 {micro}m radius, 28.5 GeV positron beam with 1.2 x 10{sup 10} particles in a 1.4 meter long 0-2 x 10{sup 14} e{sup -}/cm{sup 3} plasma is described. First the energy loss was measured as a function of plasma density and the measurements are compared to theory. Then, an energy gain of 79 {+-} 15 MeV is shown. This is the first demonstration of energy gain of a positron beam in a plasma and it is in good agreement with the predictions

High Dose MicroCT Does Not Contribute Toward Improved MicroPET/CT Image Quantitative Accuracy and Can Limit Longitudinal Scanning of Small Animals

Directory of Open Access Journals (Sweden)

Wendy A. McDougald

2017-10-01

Full Text Available Obtaining accurate quantitative measurements in preclinical Positron Emission Tomography/Computed Tomography (PET/CT imaging is of paramount importance in biomedical research and helps supporting efficient translation of preclinical results to the clinic. The purpose of this study was two-fold: (1 to investigate the effects of different CT acquisition protocols on PET/CT image quality and data quantification; and (2 to evaluate the absorbed dose associated with varying CT parameters.Methods: An air/water quality control CT phantom, tissue equivalent material phantom, an in-house 3D printed phantom and an image quality PET/CT phantom were imaged using a Mediso nanoPET/CT scanner. Collected data was analyzed using PMOD software, VivoQuant software and National Electric Manufactures Association (NEMA software implemented by Mediso. Measured Hounsfield Unit (HU in collected CT images were compared to the known HU values and image noise was quantified. PET recovery coefficients (RC, uniformity and quantitative bias were also measured.Results: Only less than 2 and 1% of CT acquisition protocols yielded water HU values < −80 and air HU values < −840, respectively. Four out of 11 CT protocols resulted in more than 100 mGy absorbed dose. Different CT protocols did not impact PET uniformity and RC, and resulted in <4% overall bias relative to expected radioactive concentration.Conclusion: Preclinical CT protocols with increased exposure times can result in high absorbed doses to the small animals. These should be avoided, as they do not contributed toward improved microPET/CT image quantitative accuracy and could limit longitudinal scanning of small animals.

Positron annihilation and electron microscopy study in the early stage of fatigue of polycrystalline copper

International Nuclear Information System (INIS)

Diaz, L.; Pareja, R.; Pedrosa, M.A.; Gonzalez, R.

1985-01-01

Positron annihilation and transmission electron microscopy are used to study the early stage of fatigue in polycrystalline copper cyclically deformed at various temperatures. The concentration of positron traps is correlated to the cumulative plastic strain and to the work done during deformation. The average lifetimes of the trapped positrons are (177 +- 4) and (186 +- 3) ps for samples fatigued at T 15 s -1 for the samples deformed at T <= 293 K. Vacancy clusters like small dislocation loops, are proposed as the main defects responsible for the positron trapping. (author)

High-resolution short-exposure small-animal laboratory x-ray phase-contrast tomography

Science.gov (United States)

Larsson, Daniel H.; Vågberg, William; Yaroshenko, Andre; Yildirim, Ali Önder; Hertz, Hans M.

2016-12-01

X-ray computed tomography of small animals and their organs is an essential tool in basic and preclinical biomedical research. In both phase-contrast and absorption tomography high spatial resolution and short exposure times are of key importance. However, the observable spatial resolutions and achievable exposure times are presently limited by system parameters rather than more fundamental constraints like, e.g., dose. Here we demonstrate laboratory tomography with few-ten μm spatial resolution and few-minute exposure time at an acceptable dose for small-animal imaging, both with absorption contrast and phase contrast. The method relies on a magnifying imaging scheme in combination with a high-power small-spot liquid-metal-jet electron-impact source. The tomographic imaging is demonstrated on intact mouse, phantoms and excised lungs, both healthy and with pulmonary emphysema.

Characterization of dual layer phoswich detector performance for small animal PET using Monte Carlo simulation

International Nuclear Information System (INIS)

Chung, Yong Hyun; Choi, Yong; Cho, Gyuseong; Choe, Yearn Seong; Lee, Kyung-Han; Kim, Byung-Tae

2004-01-01

A positron emission tomograph dedicated to small animal imaging should have high spatial resolution and sensitivity, and dual layer scintillators have been developed for this purpose. In this study, simulations were performed to optimize the order and the length of each crystal of a dual layer phoswich detector, and to evaluate the possibility of measuring signals from each layer of the phoswich detector. A simulation tool GATE was used to estimate the sensitivity and resolution of a small PET scanner. The proposed scanner is based on dual layer phoswich detector modules arranged in a ring of 10 cm diameter. Each module is composed of 8 x 8 arrays of phoswich detectors consisting of LSO and LuYAP with a 2 mm x 2 mm sensitive area coupled to a Hamamatsu R7600-00-M64 PSPMT. The length of the front layer of the phoswich detector varied from 0 to 10 mm at 1 mm intervals, and the total length (LSO + LuYAP) was fixed at 20 mm. The order of the crystal layers of the phoswich detector was also changed. Radial resolutions were kept below 3.4 mm and 3.7 mm over 8 cm FOV, and sensitivities were 7.4% and 8.0% for LSO 5 mm-LuYAP 15 mm, and LuYAP 6 mm-LSO 14 mm phoswich detectors, respectively. Whereas, high and uniform resolutions were achieved by using the LSO front layer, higher sensitivities were obtained by changing the crystal order. The feasibilities for applying crystal identification methods to phoswich detectors consisting of LSO and LuYAP were investigated using simulation and experimentally derived measurements of the light outputs from each layer of the phoswich detector. In this study, the optimal order and lengths of the dual layer phoswich detector were derived in order to achieve high sensitivity and high and uniform radial resolution

Positrons and positronium

International Nuclear Information System (INIS)

Jean, Y.C.; Lambrecht, R.M.

1988-01-01

This bibliography includes articles, proceedings, abstracts, reports and patents published between 1930 and 1984 on the subject of positrons, positron annihilation and positronium. The subject covers experimental and theoretical results in the areas of physics and chemistry of low and intermediate energy (< 0.6 MeV) positrons and positronium. The topics of interest are: fundamental properties, interactions with matter, nuclear technology, the history and philosophy of antimatter, the theory of the universe, and the applications of positrons in the chemical, physical, and biomedical sciences

The proposed INEL intense slow positron source, beam line, and positron microscope facility

International Nuclear Information System (INIS)

Makowitz, H.; Denison, A.B.; Brown, B.

1993-01-01

A program is currently underway at the Idaho National Engineering Laboratory (INEL) to design and construct an Intense Slow Positron Beam Facility with an associated Positron Microscope. Positron beams have been shown to be valuable research tools and have potential application in industrial processing and nondestructive evaluation (microelectronics, etc.). The limit of resolution or overall usefulness of the technique has been limited because of lack of sufficient intensity. The goal of the INEL positron beam is ≥ 10 12 slow e+/s over a 0.03 cm diameter which represents a 10 3 to 10 4 advancement in beam current over existing beam facilities. The INEL is an ideal site for such a facility because of the nuclear reactors capable of producing intense positron sources and the personnel and facilities capable of handling high levels of radioactivity. A design using 58 Co with moderators and remoderators in conjunction with electrostatic positron beam optics has been reached after numerous computer code studies. Proof-of-principle electron tests have demonstrated the feasibility of the large area source focusing optics. The positron microscope development is occurring in conjunction with the University of Michigan positron microscope group. Such a Beam Facility and associated Intense Slow Positron Source (ISPS) can also be utilized for the generation and study of positron, and positron electron plasmas at ≤ 10 14 particles/cm 3 with plasma temperatures ranging from an eV to many keV, as well as an intense x-ray source via positron channeling radiation. The possibility of a tunable x-ray laser based on channeling positron radiation also exists. In this discussion the authors will present a progress report on various activities associated with the INEL ISPS

Development of in-vivo micro CT system for small animals

Energy Technology Data Exchange (ETDEWEB)

Nam, Ki Yong; Lim, Jong Hyeok; Jeong, Young Jo; Park, Jeong Gwon [Institute for Radiological Imaging Science, Iksan (Korea, Republic of); Park, Jung Bung [DRGEM Corp., Seoul (Korea, Republic of); Yoon, Kwon Ha [Institute for Radiological Imaging Science and Medical School of Radiology, Iksan (Korea, Republic of)

2005-07-01

Computed tomography system with the spatial resolution of {approx}25 {mu}m has been developed for the application to small animals. This system is designed by gantry-rotation type for minimizing animal movement. To get image with micro-spatial resolution, system characteristic such as geometry between main components of source, specimen and detector, field of view, etc., is described in this paper. The requirements of x-ray spot size and CCD pixel size to approach the resolution are discussed. In-vivo imaging test for mouse is also presented as a result.

Development of in-vivo micro CT system for small animals

International Nuclear Information System (INIS)

Nam, Ki Yong; Lim, Jong Hyeok; Jeong, Young Jo; Park, Jeong Gwon; Park, Jung Bung; Yoon, Kwon Ha

2005-01-01

Computed tomography system with the spatial resolution of ∼25 μm has been developed for the application to small animals. This system is designed by gantry-rotation type for minimizing animal movement. To get image with micro-spatial resolution, system characteristic such as geometry between main components of source, specimen and detector, field of view, etc., is described in this paper. The requirements of x-ray spot size and CCD pixel size to approach the resolution are discussed. In-vivo imaging test for mouse is also presented as a result

Accessories for detention and protection used in small animals radiation therapy

International Nuclear Information System (INIS)

Vettorato, Michel Campos; Vulcano, Luiz Carlos; Fernandes, Marco Antonio Rodrigues

2016-01-01

Radiation therapy is a medical method well established in the treatment of cancer in veterinary medicine worldwide. The radiotherapy protocols applied in animals vary according to several factors. In most procedures require sedation or anesthesia of the animal and this fact imposes the use of immobilization accessories specially developed for the different species of animals and treated as their specified procedures. Therefore, this study aims to describe the types of accessories used for immobilization and for the protection of small animals undergoing radiotherapy. For its development a literature search was performed by search sites like Google Scholar, Scielo, Bireme, PubMed, and consultations in books campus library Botucatu UNESP. Despite the limitations of each accessory rated this review, it was possible to identify the use of each and how this can be advantageous for the treatment of animals undergoing radiation therapy. (author)

Computed tomography of the central nervous system in small animals

International Nuclear Information System (INIS)

Tipold, A.; Tipold, E.

1991-01-01

With computed tomography in 44 small animals some well defined anatomical structures and pathological processes of the central nervous system are described. Computed tomography is not only necessary for the diagnosis of tumors; malformations, inflammatory, degenerative and vascular diseases and traumas are also visible

Positron emission tomography

International Nuclear Information System (INIS)

Reivich, M.; Alavi, A.

1985-01-01

This book contains 24 selections. Some of the titles are: Positron Emission Tomography Instrumentation, Generator Systems for Positron Emitters, Reconstruction Algorithms, Cerebral Glucose Consumption: Methodology and Validation, Cerebral Blood Flow Tomography Using Xenon-133 Inhalation: Methods and Clinical Applications, PET Studies of Stroke, Cardiac Positron Emission Tomography, and Use of PET in Oncology

Design of a multimodal fibers optic system for small animal optical imaging.

Science.gov (United States)

Spinelli, Antonello E; Pagliazzi, Marco; Boschi, Federico

2015-02-01

Small animals optical imaging systems are widely used in pre-clinical research to image in vivo the bio-distribution of light emitting probes using fluorescence or bioluminescence modalities. In this work we presented a set of simulated results of a novel small animal optical imaging module based on a fibers optics matrix, coupled with a position sensitive detector, devoted to acquire bioluminescence and Cerenkov images. Simulations were performed using GEANT 4 code with the GAMOS architecture using the tissue optics plugin. Results showed that it is possible to image a 30 × 30 mm region of interest using a fiber optics array containing 100 optical fibers without compromising the quality of the reconstruction. The number of fibers necessary to cover an adequate portion of a small animal is thus quite modest. This design allows integrating the module with magnetic resonance (MR) in order to acquire optical and MR images at the same time. A detailed model of the mouse anatomy, obtained by segmentation of 3D MRI images, will improve the quality of optical 3D reconstruction. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Preliminary Experience with Small Animal SPECT Imaging on Clinical Gamma Cameras

Directory of Open Access Journals (Sweden)

P. Aguiar

2014-01-01

Full Text Available The traditional lack of techniques suitable for in vivo imaging has induced a great interest in molecular imaging for preclinical research. Nevertheless, its use spreads slowly due to the difficulties in justifying the high cost of the current dedicated preclinical scanners. An alternative for lowering the costs is to repurpose old clinical gamma cameras to be used for preclinical imaging. In this paper we assess the performance of a portable device, that is, working coupled to a single-head clinical gamma camera, and we present our preliminary experience in several small animal applications. Our findings, based on phantom experiments and animal studies, provided an image quality, in terms of contrast-noise trade-off, comparable to dedicated preclinical pinhole-based scanners. We feel that our portable device offers an opportunity for recycling the widespread availability of clinical gamma cameras in nuclear medicine departments to be used in small animal SPECT imaging and we hope that it can contribute to spreading the use of preclinical imaging within institutions on tight budgets.

Cardiac positron emission tomography

International Nuclear Information System (INIS)

Eftekhari, M.; Ejmalian, G.

2003-01-01

Positron emission tomography is an intrinsically tool that provide a unique and unparalleled approach for clinicians and researchers to interrogate the heart noninvasively. The ability to label substances of physiological interest with positron-emitting radioisotopes has permitted insight into normal blood flow and metabolism and the alterations that occur with disease states. Positron emission tomography of the heart has evolved as a unique, noninvasive approach for the assessment of myocardial perfusion, metabolism, and function. Because of the intrinsic quantitative nature of positron emission tomography measurements as well as the diverse compounds that can be labeled with positron- emitting radioisotopes, studies with positron emission tomography have provided rich insight into the physiology of the heart under diverse conditions

SU-E-T-124: Anthropomorphic Phantoms for Confirmation of Linear Accelerator Based Small Animal Irradiation

Energy Technology Data Exchange (ETDEWEB)

Perks, J; Benedict, S [UC Davis Cancer Center, Sacramento, CA (United States); Lucero, S [UC Davis, Davis, CA (United States)

2015-06-15

Purpose: To document the support of radiobiological small animal research by a modern radiation oncology facility. This study confirms that a standard, human use linear accelerator can cover the range of experiments called for by researchers performing animal irradiation. A number of representative, anthropomorphic murine phantoms were made. The phantoms confirmed the small field photon and electron beams dosimetry validated the use of the linear accelerator for rodents. Methods: Laser scanning a model, CAD design and 3D printing produced the phantoms. The phantoms were weighed and CT scanned to judge their compatibility to real animals. Phantoms were produced to specifically mimic lung, gut, brain, and othotopic lesion irradiations. Each phantom was irradiated with the same protocol as prescribed to the live animals. Delivered dose was measured with small field ion chambers, MOS/FETs or TLDs. Results: The density of the phantom material compared to density range across the real mice showed that the printed material would yield sufficiently accurate measurements when irradiated. The whole body, lung and gut irradiations were measured within 2% of prescribed doses with A1SL ion chamber. MOSFET measurements of electron irradiations for the orthotopic lesions allowed refinement of the measured small field output factor to better than 2% and validated the immunology experiment of irradiating one lesion and sparing another. Conclusion: Linacs are still useful tools in small animal bio-radiation research. This work demonstrated a strong role for the clinical accelerator in small animal research, facilitating standard whole body dosing as well as conformal treatments down to 1cm field. The accuracy of measured dose, was always within 5%. The electron irradiations of the phantom brain and flank tumors needed adjustment; the anthropomorphic phantoms allowed refinement of the initial output factor measurements for these fields which were made in a large block of solid water.

BEPC II positron source

International Nuclear Information System (INIS)

Pei Guoxi; Sun Yaolin; Liu Jintong; Chi Yunlong; Liu Yucheng; Liu Nianzong

2006-01-01

BEPC II-an upgrade project of the Beijing Electron Positron Collider (BEPC) is a factory type of e + e - collider. The fundamental requirements for its injector linac are the beam energy of 1.89 GeV for on-energy injection and a 40 mA positron beam current at the linac end with a low beam emittance of 1.6 μm and a low energy spread of ±0.5% so as to guarantee a higher injection rate (≥50 mA/min) to the storage ring. Since the positron flux is proportional to the primary electron beam power on the target, the authors will increase the electron gun current from 4A to 10A by using a new electron gun system and increase the primary electron energy from 120 MeV to 240 MeV. The positron source itself is an extremely important system for producing more positrons, including a positron converter target chamber, a 12kA flux modulator, the 7m focusing module with DC power supplies and the support. The new positron production linac from the electron gun to the positron source has been installed into the tunnel. In what follows, the authors will emphasize the positron source design, manufacture and tests. (authors)

Positron Scanning of Liver and Pancreas; Exploration de Foie et du Pancreas par les Positrons; Pozitronoskopiya pecheni i podzheludochnoj zhelezy; Exploracion del higado y del pancreas mediante positrones

Energy Technology Data Exchange (ETDEWEB)

Aronow, S; Thors, R; Brownell, G L [Physics Research Laboratory and Department of Surgery, Massachusetts General Hospital, Boston, MA (United States)

1959-07-01

The success of the positron scanning technique in the localization of brain tumors has suggested its application to other organs. Zinc-62 is used in an attempt to delineate the pancreas and copper-64 in various forms is used to delineate the liver. The problem of visualizing the pancreas is particularly difficult because of its small size and the presence of large organs in the vicinity which concentrate zinc. Several approaches to this problem are discussed. Copper-64 in simple ionic form and in the form of copper versenate concentrate to a marked degree in the liver. Positron scans of the liver would seem to offer considerable promise for successful 'diagnosis of various liver disorders. Data is presented on the distribution of several isotopes and compounds in animals. (author) [French] Devant le succes avec lequel la technique de detection par les positrons a ete utilisee pour la localisation des tumeurs du cerveau, on a ete amene a l'appliquer a d'autres organes. On s'est servi de zinc-62 pour tenter de determiner le contour du pancreas, et de cuivre-64, sous diverses formes, pour le contour du foie. Il est particulieremen t difficile de rendre visible le pancreas en raison de sa petite taille et de la presence d'organes voisins de grandes dimensions, qui concentrent le zinc. Les auteurs etudient plusieurs procedes par lesquels on s'est efforce de resoudre ce probleme. Le cuivre-64 sous forme ionique simple et sous forme de sel de l'acide ethylene-diamino-tetra-acetique se ooncentre fortement dans le foie. L'exploration du foie a l'aide des positrons parait devoir faciliter considerablemen t le diagnostic de differents troubles hepatiques. Les auteurs donnent des indications sur la repartition de plusieurs isotopes et composes chez des animaux. (author) [Spanish] El exito de la tecnica de exploracion mediante positrones en la localization de tumores cerebrales aconseja su aplicacion a otros organos. El zinc-62 y el cobre-64 en diferentes formas se utilizan

Positron annihilation studies on bulk metallic glass and high intensity positron beam developments

International Nuclear Information System (INIS)

Asoka-Kumar, P.; Stoeffl, W.

2003-01-01

Positron annihilation spectroscopy is an ideal probe to examine atomic scale open-volume regions in materials. Below, we summarize the recent results on studies of open-volume regions of a multicomponent Zr-Ti-Ni-Cu-Be bulk metallic glass. Our studies establish two types of open-volume regions, one group that is too shallow to trap positrons at room temperature and becomes effective only at low temperatures and the other group that localizes positrons at room temperature and is large enough to accommodate hydrogen. The second half of the paper will concentrate on the high intensity positron program at Lawrence Livermore National Laboratory. A new positron production target is under development and we are constructing two experimental end stations to accommodate a pulsed positron microprobe and an experiment on positron diffraction and holography. Important design considerations of these experiments will be described. (author)

Positron annihilation studies of high dose Sb implanted silicon

International Nuclear Information System (INIS)

Schut, H.; Eijt, S.W.H.; Beling, C.D.; Ho, K.; Takamura, Y.

2005-01-01

The formation and evolution of vacancies and precipitates created by implantation of 60 keV, 2 x 10 16 cm -2 Sb + in pre-amorphized (0 0 1) Cz-Si is studied using the Doppler broadening (DB) and two-dimensional angular correlation of annihilation radiation (2D-ACAR) positron beam techniques. After implantation, samples were laser annealed (LTA) and subsequently thermal annealed at temperatures ranging from 400 to 1000 deg. C. Implantation-induced vacancy-type defects were detected up to a depth of 280 nm. After LTA, positron annihilation related to both Sb and remaining defects is observed in the first 100 nm below the surface. The deeper region only shows positron trapping at vacancy-type defects with strong reduced concentration. Complete removal is obtained after 600 deg. C anneal. At this temperature, the positron data for the upper region reveals trapping at Sb and Si sites only. With increasing annealing time (at 600 deg. C) or increasing temperature (up to 1000 deg. C) positron annihilation at Sb-sites associated with neighboring vacancies becomes apparent. Results are correlated with the observed Sb electrical deactivation above 600 deg. C, the shift from small Sb aggregates to precipitates and out-diffusion of Sb from the implantation region at higher temperatures

On the average luminosity of electron positron collider and positron-producing energy

International Nuclear Information System (INIS)

Xie Jialin

1985-01-01

In this paper, the average luminosity of linac injected electron positron collider is investigated from the positron-producing energy point of view. When the energy of the linac injector is fixed to be less than the operating energy of the storage ring, it has been found that there exists a positron-producing energy to give optimum average luminosity. Two cases have been studied, one for an ideal storage ring with no single-beam instability and the other for practical storage ring with fast head-tail instability. The result indicates that there is a positron-producing energy corresponding to the minimum injection time, but this does not correspond to the optimum average luminosity for the practical storage rings. For Beijing Electron Positron Collider (BEPC), the positron-producing energy corresponding to the optimum average luminosity is about one tenth of the total injector energy

Characterization of a high-purity germanium detector for small-animal SPECT.

Science.gov (United States)

Johnson, Lindsay C; Campbell, Desmond L; Hull, Ethan L; Peterson, Todd E

2011-09-21

We present an initial evaluation of a mechanically cooled, high-purity germanium double-sided strip detector as a potential gamma camera for small-animal SPECT. It is 90 mm in diameter and 10 mm thick with two sets of 16 orthogonal strips that have a 4.5 mm width with a 5 mm pitch. We found an energy resolution of 0.96% at 140 keV, an intrinsic efficiency of 43.3% at 122 keV and a FWHM spatial resolution of approximately 1.5 mm. We demonstrated depth-of-interaction estimation capability through comparison of pinhole acquisitions with a point source on and off axes. Finally, a flood-corrected flood image exhibited a strip-level uniformity of less than 1%. This high-purity germanium offers many desirable properties for small-animal SPECT.

Positron emission tomography

International Nuclear Information System (INIS)

Paans, A.M.J.

1981-01-01

Positron emitting radiopharmaceuticals have special applications in in-vivo studies of biochemical processes. The combination of a cyclotron for the production of radionuclides and a positron emission tomograph for the registration of the distribution of radioactivity in the body enables the measurement of local radioactivity concentration in tissues, and opens up new possibilities in the diagnosis and examination of abnormalities in the metabolism. The principles and procedures of positron emission tomography are described and the necessary apparatus considered, with emphasis on the positron camera. The first clinical applications using 55 Co bloemycine for tumor detection are presented. (C.F.)

Study of a positron source generated by photons from ultrarelativistic channeled particles

International Nuclear Information System (INIS)

Chehab, R.; Couchot, F.; Nyaiesh, A.R.; Richard, F.; Artru, X.

1989-03-01

Radiation by channeled electrons in Germanium and Silicon crystals along the axis is studied as a very promising photon source of small angular divergence for positron generation in amorphous targets. Radiation rates for different crystal lengths - from some tenths of mm to 10 mm - and two electron incident energies, 5 and 20 GeV, are considered and a comparison between the two crystals is presented. Thermic behaviour of the crystal under incidence of bunches of 10 10 electrons is also examined. The corresponding positron yields for tungsten amorphous converters - of 0.5 and 1 X o thickness - are calculated considering the case of a Germanium photon generator. Assuming a large acceptance optical matching system as the adiabatic device of the SLC, accepted positrons are evaluated and positron yields larger than 1 e + /e - are obtained

Development of a Magnetoencephalograph System for Small Animals

International Nuclear Information System (INIS)

Kim, J. E.; Kim, I. S.; Kang, C. S.; Kwon, H.; Kim, J. M.; Lee, Y. H.; Kim, K.

2011-01-01

We developed a four-channel first order gradiometer system to measure magnetoencephalogram for mice. We used double relaxation oscillation SQUID (DROS). The diameter of the pickup coil is 4 mm and the distance between the coils is 5 mm. Coil distance was designed to have good spatial resolution for a small mouse brain. We evaluated the current dipole localization confidence region for a mouse brain, using the spherical conductor model. The white noise of the measurement system was about 30 fT/Hz 1/2 /cm when measured in a magnetically shielded room. We measured magnetic signal from a phantom having the same size of a mouse brain, which was filled with 0.9% saline solution. The results suggest that the developed system has a feasibility to study the functions of brain of small animals.

Improvement of semi-quantitative small-animal PET data with recovery coefficients: a phantom and rat study.

Science.gov (United States)

Aide, Nicolas; Louis, Marie-Hélène; Dutoit, Soizic; Labiche, Alexandre; Lemoisson, Edwige; Briand, Mélanie; Nataf, Valérie; Poulain, Laurent; Gauduchon, Pascal; Talbot, Jean-Noël; Montravers, Françoise

2007-10-01

To evaluate the accuracy of semi-quantitative small-animal PET data, uncorrected for attenuation, and then of the same semi-quantitative data corrected by means of recovery coefficients (RCs) based on phantom studies. A phantom containing six fillable spheres (diameter range: 4.4-14 mm) was filled with an 18F-FDG solution (spheres/background activity=10.1, 5.1 and 2.5). RCs, defined as measured activity/expected activity, were calculated. Nude rats harbouring tumours (n=50) were imaged after injection of 18F-FDG and sacrificed. The standardized uptake value (SUV) in tumours was determined with small-animal PET and compared to ex-vivo counting (ex-vivo SUV). Small-animal PET SUVs were corrected with RCs based on the greatest tumour diameter. Tumour proliferation was assessed with cyclin A immunostaining and correlated to the SUV. RCs ranged from 0.33 for the smallest sphere to 0.72 for the largest. A sigmoidal correlation was found between RCs and sphere diameters (r(2)=0.99). Small-animal PET SUVs were well correlated with ex-vivo SUVs (y=0.48x-0.2; r(2)=0.71) and the use of RCs based on the greatest tumour diameter significantly improved regression (y=0.84x-0.81; r(2)=0.77), except for tumours with important necrosis. Similar results were obtained without sacrificing animals, by using PET images to estimate tumour dimensions. RC-based corrections improved correlation between small-animal PET SUVs and tumour proliferation (uncorrected data: Rho=0.79; corrected data: Rho=0.83). Recovery correction significantly improves both accuracy of small-animal PET semi-quantitative data in rat studies and their correlation with tumour proliferation, except for largely necrotic tumours.

New techniques of positron annihilation

International Nuclear Information System (INIS)

1983-02-01

Studies on new techniques of positron annihilation and its application to various fields are presented. First, production of slow positron and its characteristic features are described. The slow positron can be obtained from radioisotopes by using a positron moderator, proton beam bombardment on a boron target, and pair production by using an electron linear accelerator. Bright enhancement of the slow positron beam is studied. Polarized positron beam can be used for the study of the momentum distribution of an electron in ferromagnetic substances. Production of polarized positrons and measurements of polarization are discussed. Various phases of interaction between slow positrons and atoms (or molecules) are described. A comparative study of electron scavenging effects on luminescence and on positronium formation in cyclohexane is presented. The positron annihilation phenomena are applicable for the surface study. The microscopic information on the surface of porous material may be obtained. The slow positrons are also useful for the surface study. Production and application of slow muon (positive and negative) are presented in this report. (Kato, T.)

Solvated Positron Chemistry - Positron Reactions with Pseudo-Halide Ions in Water

DEFF Research Database (Denmark)

Mogensen, O. E.; Pedersen, Niels Jørgen; Andersen, Jan Rud

1982-01-01

The hydrated positron e+aq reactions with SCN−, OCN−, CN−, S2− were studied by means of the angular correlation technique. The positron forms bound states with SCN−, CN−, and S2− but not with OCN−. Apparently, the e+aq reaction with SH− results in a positron bound state with S2−. It was difficult...

Dynamic positron emission tomography in man using small bismuth germanate crystals

International Nuclear Information System (INIS)

Derenzo, S.E.; Budinger, T.F.; Huesman, R.H.; Cahoon, J.L.

1982-04-01

Primary considerations for the design of positron emission tomographs for medical studies in humans are the need for high imaging sensitivity, whole organ coverage, good spatial resolution, high maximum data rates, adequate spatial sampling with minimum mechanical motion, shielding against out of plane activity, pulse height discrimination against scattered photons, and timing discrimination against accidental coincidences. We discuss the choice of detectors, sampling motion, shielding, and electronics to meet these objectives

SiliPET: An ultra-high resolution design of a small animal PET scanner based on stacks of double-sided silicon strip detector

International Nuclear Information System (INIS)

Di Domenico, Giovanni; Zavattini, Guido; Cesca, Nicola; Auricchio, Natalia; Andritschke, Robert; Schopper, Florian; Kanbach, Gottfried

2007-01-01

We investigated with Monte Carlo simulations, using the EGSNrcMP code, the capabilities of a small animal PET scanner based on four stacks of double-sided silicon strip detectors. Each stack consists of 40 silicon detectors with dimension of 60x60x1 mm 3 and 128 orthogonal strips on each side. Two coordinates of the interaction are given by the strips, whereas the third coordinate is given by the detector number in the stack. The stacks are arranged to form a box of 5x5x6 cm 3 with minor sides opened; the box represents the minimal FOV of the scanner. The performance parameters of the SiliPET scanner have been estimated giving a (positron range limited) spatial resolution of 0.52 mm FWHM, and an absolute sensitivity of 5.1% at the center of system. Preliminary results of a proof of principle measurement done with the MEGA advanced Compton imager using a ∼1 mm diameter 22 Na source, showed a focal ray tracing FWHM of 1 mm

Measurement of flow velocity fields in small vessel-mimic phantoms and vessels of small animals using micro ultrasonic particle image velocimetry (micro-EPIV).

Science.gov (United States)

Qian, Ming; Niu, Lili; Wang, Yanping; Jiang, Bo; Jin, Qiaofeng; Jiang, Chunxiang; Zheng, Hairong

2010-10-21

Determining a multidimensional velocity field within microscale opaque fluid flows is needed in areas such as microfluidic devices, biofluid mechanics and hemodynamics research in animal studies. The ultrasonic particle image velocimetry (EchoPIV) technique is appropriate for measuring opaque flows by taking advantage of PIV and B-mode ultrasound contrast imaging. However, the use of clinical ultrasound systems for imaging flows in small structures or animals has limitations associated with spatial resolution. This paper reports on the development of a high-resolution EchoPIV technique (termed as micro-EPIV) and its application in measuring flows in small vessel-mimic phantoms and vessels of small animals. Phantom experiments demonstrate the validity of the technique, providing velocity estimates within 4.1% of the analytically derived values with regard to the flows in a small straight vessel-mimic phantom, and velocity estimates within 5.9% of the computationally simulated values with regard to the flows in a small stenotic vessel-mimic phantom. Animal studies concerning arterial and venous flows of living rats and rabbits show that the micro-EPIV-measured peak velocities within several cardiac cycles are about 25% below the values measured by the ultrasonic spectral Doppler technique. The micro-EPIV technique is able to effectively measure the flow fields within microscale opaque fluid flows.

Measurement of flow velocity fields in small vessel-mimic phantoms and vessels of small animals using micro ultrasonic particle image velocimetry (micro-EPIV)

International Nuclear Information System (INIS)

Qian Ming; Niu Lili; Jiang Bo; Jin Qiaofeng; Jiang Chunxiang; Zheng Hairong; Wang Yanping

2010-01-01

Determining a multidimensional velocity field within microscale opaque fluid flows is needed in areas such as microfluidic devices, biofluid mechanics and hemodynamics research in animal studies. The ultrasonic particle image velocimetry (EchoPIV) technique is appropriate for measuring opaque flows by taking advantage of PIV and B-mode ultrasound contrast imaging. However, the use of clinical ultrasound systems for imaging flows in small structures or animals has limitations associated with spatial resolution. This paper reports on the development of a high-resolution EchoPIV technique (termed as micro-EPIV) and its application in measuring flows in small vessel-mimic phantoms and vessels of small animals. Phantom experiments demonstrate the validity of the technique, providing velocity estimates within 4.1% of the analytically derived values with regard to the flows in a small straight vessel-mimic phantom, and velocity estimates within 5.9% of the computationally simulated values with regard to the flows in a small stenotic vessel-mimic phantom. Animal studies concerning arterial and venous flows of living rats and rabbits show that the micro-EPIV-measured peak velocities within several cardiac cycles are about 25% below the values measured by the ultrasonic spectral Doppler technique. The micro-EPIV technique is able to effectively measure the flow fields within microscale opaque fluid flows.

Positron-Induced Luminescence

Science.gov (United States)

Stenson, E. V.; Hergenhahn, U.; Stoneking, M. R.; Pedersen, T. Sunn

2018-04-01

We report on the observation that low-energy positrons incident on a phosphor screen produce significantly more luminescence than electrons do. For two different wide-band-gap semiconductor phosphors (ZnS:Ag and ZnO:Zn), we compare the luminescent response to a positron beam with the response to an electron beam. For both phosphors, the positron response is significantly brighter than the electron response, by a factor that depends strongly on incident energy (0-5 keV). Positrons with just a few tens of electron-volts of energy (for ZnS:Ag) or less (for ZnO:Zn) produce as much luminescence as is produced by electrons with several kilo-electron-volts. We attribute this effect to valence band holes and excited electrons produced by positron annihilation and subsequent Auger processes. These results demonstrate a valuable approach for addressing long-standing questions about luminescent materials.

Geo-PET: A novel generic organ-pet for small animal organs and tissues

Science.gov (United States)

Sensoy, Levent

Reconstructed tomographic image resolution of small animal PET imaging systems is improving with advances in radiation detector development. However the trend towards higher resolution systems has come with an increase in price and system complexity. Recent developments in the area of solid-state photomultiplication devices like silicon photomultiplier arrays (SPMA) are creating opportunities for new high performance tools for PET scanner design. Imaging of excised small animal organs and tissues has been used as part of post-mortem studies in order to gain detailed, high-resolution anatomical information on sacrificed animals. However, this kind of ex-vivo specimen imaging has largely been limited to ultra-high resolution muCT. The inherent limitations to PET resolution have, to date, excluded PET imaging from these ex-vivo imaging studies. In this work, we leverage the diminishing physical size of current generation SPMA designs to create a very small, simple, and high-resolution prototype detector system targeting ex-vivo tomographic imaging of small animal organs and tissues. We investigate sensitivity, spatial resolution, and the reconstructed image quality of a prototype small animal PET scanner designed specifically for imaging of excised murine tissue and organs. We aim to demonstrate that a cost-effective silicon photomultiplier (SiPM) array based design with thin crystals (2 mm) to minimize depth of interaction errors might be able to achieve sub-millimeter resolution. We hypothesize that the substantial decrease in sensitivity associated with the thin crystals can be compensated for with increased solid angle detection, longer acquisitions, higher activity and wider acceptance energy windows (due to minimal scatter from excised organs). The constructed system has a functional field of view (FoV) of 40 mm diameter, which is adequate for most small animal specimen studies. We perform both analytical (3D-FBP) and iterative (ML-EM) methods in order to

Quantum chemical approach for positron annihilation spectra of atoms and molecules beyond plane-wave approximation

Science.gov (United States)

Ikabata, Yasuhiro; Aiba, Risa; Iwanade, Toru; Nishizawa, Hiroaki; Wang, Feng; Nakai, Hiromi

2018-05-01

We report theoretical calculations of positron-electron annihilation spectra of noble gas atoms and small molecules using the nuclear orbital plus molecular orbital method. Instead of a nuclear wavefunction, the positronic wavefunction is obtained as the solution of the coupled Hartree-Fock or Kohn-Sham equation for a positron and the electrons. The molecular field is included in the positronic Fock operator, which allows an appropriate treatment of the positron-molecule repulsion. The present treatment succeeds in reproducing the Doppler shift, i.e., full width at half maximum (FWHM) of experimentally measured annihilation (γ-ray) spectra for molecules with a mean absolute error less than 10%. The numerical results indicate that the interpretation of the FWHM in terms of a specific molecular orbital is not appropriate.

Control of positive end-expiratory pressure (PEEP for small animal ventilators

Directory of Open Access Journals (Sweden)

Leão Nunes Marcelo V

2010-07-01

Full Text Available Abstract Background The positive end-expiratory pressure (PEEP for the mechanical ventilation of small animals is frequently obtained with water seals or by using ventilators developed for human use. An alternative mechanism is the use of an on-off expiratory valve closing at the moment when the alveolar pressure is equal to the target PEEP. In this paper, a novel PEEP controller (PEEP-new and the PEEP system of a commercial small-animal ventilator, both based on switching an on-off valve, are evaluated. Methods The proposed PEEP controller is a discrete integrator monitoring the error between the target PEEP and the airways opening pressure prior to the onset of an inspiratory cycle. In vitro as well as in vivo experiments with rats were carried out and the PEEP accuracy, settling time and under/overshoot were considered as a measure of performance. Results The commercial PEEP controller did not pass the tests since it ignores the airways resistive pressure drop, resulting in a PEEP 5 cmH2O greater than the target in most conditions. The PEEP-new presented steady-state errors smaller than 0.5 cmH2O, with settling times below 10 s and under/overshoot smaller than 2 cmH2O. Conclusion The PEEP-new presented acceptable performance, considering accuracy and temporal response. This novel PEEP generator may prove useful in many applications for small animal ventilators.

Positron scattering and annihilation from hydrogenlike ions

International Nuclear Information System (INIS)

Novikov, S.A.; Bromley, M.W.J.; Mitroy, J.

2004-01-01

The Kohn variational method is used with a configuration-interaction-type wave function to determine the J=0 and J=1 phase shifts and annihilation parameter Z eff for positron-hydrogenic ion scattering. The phase shifts are within 1-2% of the best previous calculations. The values of Z eff are small and do not exceed unity for any of the momenta considered. At thermal energies Z eff is minute with a value of order 10 -50 occurring for He + at k=0.05a 0 -1 . In addition to the variational calculations, analytic expressions for the phase shift and annihilation parameters within the Coulomb wave Born approximation are derived and used to help elucidate the dynamics of positron collisions with positive ions

Coil concepts for rapid and motion-compensated MR-Imaging of small animals

International Nuclear Information System (INIS)

Korn, Matthias

2009-01-01

In this work radiofrequency-coils for the imaging of small animals in clinical whole-body MRI-systems were developed. Therefore in a first step single-channel solenoids were designed and characterized. The solenoids had two and three windings respectively, which were implemented as double wires to increase the homogeneity of the receive profile. These coils allow the acquisition of whole-body images of mice with high signal-to-noise ratio and homogeneity over a distance of at least 6.3 cm. Since many imaging experiments require rapid image acquisition, in the next step a novel coil concept was developed, which, due to its geometry, enables parallel imaging in arbitrary directions. A prototype was assembled and tested on phantom and small-animal experiments. With an accelerating factor of R=2, the difference of the SNR in all directions from the theoretical maximum, was less than 1%. In order to compensate physiological motion by the self-gating technique, in this work a coil is presented for the first time, which selectively amplifies the self-gating signal, while - due to a optical detuning technique - preserving the homogeneous illumination of the image. In vivo experiments on a small animal show an amplification of the self-gating signal by at least 40%. (orig.)

Reaction-based small-molecule fluorescent probes for dynamic detection of ROS and transient redox changes in living cells and small animals.

Science.gov (United States)

Lü, Rui

2017-09-01

Dynamic detection of transient redox changes in living cells and animals has broad implications for human health and disease diagnosis, because intracellular redox homeostasis regulated by reactive oxygen species (ROS) plays important role in cell functions, normal physiological functions and some serious human diseases (e.g., cancer, Alzheimer's disease, diabetes, etc.) usually have close relationship with the intracellular redox status. Small-molecule ROS-responsive fluorescent probes can act as powerful tools for dynamic detection of ROS and redox changes in living cells and animals through fluorescence imaging techniques; and great advances have been achieved recently in the design and synthesis of small-molecule ROS-responsive fluorescent probes. This article highlights up-to-date achievements in designing and using the reaction-based small-molecule fluorescent probes (with high sensitivity and selectivity to ROS and redox cycles) in the dynamic detection of ROS and transient redox changes in living cells and animals through fluorescence imaging. Copyright © 2017. Published by Elsevier Ltd.

Enclosure for small animals during awake animal imaging

Science.gov (United States)

Goddard, Jr., James S

2013-11-26

An enclosure or burrow restrains an awake animal during an imaging procedure. A tubular body, made from a radiolucent material that does not attenuate x-rays or gamma rays, accepts an awake animal. A proximal end of the body includes an attachment surface that corresponds to an attachment surface of an optically transparent and optically uniform window. An anti-reflective coating may be applied to an inner surface, an outer surface, or both surfaces of the window. Since the window is a separate element of the enclosure and it is not integrally formed as part of the body, it can be made with optically uniform thickness properties for improved motion tracking of markers on the animal with a camera during the imaging procedure. The motion tracking information is then used to compensate for animal movement in the image.

Importance of Attenuation Correction (AC) for Small Animal PET Imaging

DEFF Research Database (Denmark)

El Ali, Henrik H.; Bodholdt, Rasmus Poul; Jørgensen, Jesper Tranekjær

2012-01-01

was performed. Methods: Ten NMRI nude mice with subcutaneous implantation of human breast cancer cells (MCF-7) were scanned consecutively in small animal PET and CT scanners (MicroPETTM Focus 120 and ImTek’s MicroCATTM II). CT-based AC, PET-based AC and uniform AC methods were compared. Results: The activity...

Positron Factory project

Energy Technology Data Exchange (ETDEWEB)

Okada, Sohei; Sunaga, Hiromi; Kaneko, Hirohisa; Kawasuso, Atsuo; Masuno, Shin-ichi; Takizawa, Haruki; Yotsumoto, Keiichi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1997-03-01

We have started drafting a construction program for the Positron Factory, in which linac-based intense monoenergetic positron beams are planned to be applied for materials science, biotechnology and basic physics and chemistry. A technical survey study confirmed the feasibility of manufacturing a dedicated electron linac of 100 kW class with a beam energy of 100 MeV, which will produce a world-highest monoenergetic positron beam of more than 10{sup 10}/sec in intensity. A self-driven rotating converter (electrons to positrons and photons) suitable for the high power electron beam was devised and successfully tested. The practicability of simultaneous extraction of multi-channel monoenergetic positron beams with multiple moderator assemblies, which had been originated on the basis of a Monte Carlo simulation, was demonstrated by an experiment using an electron linac. An efficient moderator structure, which is composed of honeycomb-like assembled moderator foils and reflectors, is also proposed. (author)

Dynamic 11C-methionine PET analysis has an additional value for differentiating malignant tumors from granulomas: an experimental study using small animal PET

International Nuclear Information System (INIS)

Zhao, Songji; Zhao, Yan; Kuge, Yuji; Hatano, Toshiyuki; Yi, Min; Kohanawa, Masashi; Magota, Keiichi; Tamaki, Nagara; Nishijima, Ken-ichi

2011-01-01

We evaluated whether the dynamic profile of L- 11 C-methionine ( 11 C-MET) may have an additional value in differentiating malignant tumors from granulomas in experimental rat models by small animal positron emission tomography (PET). Rhodococcus aurantiacus and allogenic rat C6 glioma cells were inoculated, respectively, into the right and left calf muscles to generate a rat model bearing both granulomas and tumors (n = 6). Ten days after the inoculations, dynamic 11 C-MET PET was performed by small animal PET up to 120 min after injection of 11 C-MET. The next day, after overnight fasting, the rats were injected with 18 F-2-deoxy-2-fluoro-D-glucose ( 18 F-FDG), and dynamic 18 F-FDG PET was performed up to 180 min. The time-activity curves, static images, and mean standardized uptake value (SUV) in the lesions were calculated. 11 C-MET uptake in the granuloma showed a slow exponential clearance after an initial distribution, while the uptake in the tumor gradually increased with time. The dynamic pattern of 11 C-MET uptake in the granuloma was significantly different from that in the tumor (p 11 C-MET, visual assessment and SUV analysis could not differentiate the tumor from the granuloma in all cases, although the mean SUV in the granuloma (1.48 ± 0.09) was significantly lower than that in the tumor (1.72 ± 0.18, p 18 F-FDG in the granuloma were similar to those in the tumor (p = NS). Dynamic 11 C-MET PET has an additional value for differentiating malignant tumors from granulomatous lesions, which deserves further elucidation in clinical settings. (orig.)

Monitoring of small laboratory animal experiments by a designated web-based database.

Science.gov (United States)

Frenzel, T; Grohmann, C; Schumacher, U; Krüll, A

2015-10-01

Multiple-parametric small animal experiments require, by their very nature, a sufficient number of animals which may need to be large to obtain statistically significant results.(1) For this reason database-related systems are required to collect the experimental data as well as to support the later (re-) analysis of the information gained during the experiments. In particular, the monitoring of animal welfare is simplified by the inclusion of warning signals (for instance, loss in body weight >20%). Digital patient charts have been developed for human patients but are usually not able to fulfill the specific needs of animal experimentation. To address this problem a unique web-based monitoring system using standard MySQL, PHP, and nginx has been created. PHP was used to create the HTML-based user interface and outputs in a variety of proprietary file formats, namely portable document format (PDF) or spreadsheet files. This article demonstrates its fundamental features and the easy and secure access it offers to the data from any place using a web browser. This information will help other researchers create their own individual databases in a similar way. The use of QR-codes plays an important role for stress-free use of the database. We demonstrate a way to easily identify all animals and samples and data collected during the experiments. Specific ways to record animal irradiations and chemotherapy applications are shown. This new analysis tool allows the effective and detailed analysis of huge amounts of data collected through small animal experiments. It supports proper statistical evaluation of the data and provides excellent retrievable data storage. © The Author(s) 2015.

Development of a Magnetoencephalograph System for Small Animals

Energy Technology Data Exchange (ETDEWEB)

Kim, J. E.; Kim, I. S.; Kang, C. S.; Kwon, H.; Kim, J. M.; Lee, Y. H.; Kim, K. [Brain and Cognition Measurement Laboratory, Korea Research Institute of Standards and Science(KRISS), Daejeon (Korea, Republic of)

2011-08-15

We developed a four-channel first order gradiometer system to measure magnetoencephalogram for mice. We used double relaxation oscillation SQUID (DROS). The diameter of the pickup coil is 4 mm and the distance between the coils is 5 mm. Coil distance was designed to have good spatial resolution for a small mouse brain. We evaluated the current dipole localization confidence region for a mouse brain, using the spherical conductor model. The white noise of the measurement system was about 30 fT/Hz{sup 1/2}/cm when measured in a magnetically shielded room. We measured magnetic signal from a phantom having the same size of a mouse brain, which was filled with 0.9% saline solution. The results suggest that the developed system has a feasibility to study the functions of brain of small animals.

KEK-IMSS Slow Positron Facility

Energy Technology Data Exchange (ETDEWEB)

Hyodo, T; Wada, K; Yagishita, A; Kosuge, T; Saito, Y; Kurihara, T; Kikuchi, T; Shirakawa, A; Sanami, T; Ikeda, M; Ohsawa, S; Kakihara, K; Shidara, T, E-mail: toshio.hyodo@kek.jp [High Energy Accelerator Research Organization (KEK) 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan)

2011-12-01

The Slow Positron Facility at the Institute of Material Structure Science (IMSS) of High Energy Accelerator Research Organization (KEK) is a user dedicated facility with an energy tunable (0.1 - 35 keV) slow positron beam produced by a dedicated 55MeV linac. The present beam line branches have been used for the positronium time-of-flight (Ps-TOF) measurements, the transmission positron microscope (TPM) and the photo-detachment of Ps negative ions (Ps{sup -}). During the year 2010, a reflection high-energy positron diffraction (RHEPD) measurement station is going to be installed. The slow positron generator (converter/ moderator) system will be modified to get a higher slow positron intensity, and a new user-friendly beam line power-supply control and vacuum monitoring system is being developed. Another plan for this year is the transfer of a {sup 22}Na-based slow positron beam from RIKEN. This machine will be used for the continuous slow positron beam applications and for the orientation training of those who are interested in beginning researches with a slow positron beam.

Positron deposition in plasmas by positronium beam ionization and transport of positrons in tokamak plasmas

International Nuclear Information System (INIS)

Murphy, T.J.

1986-11-01

In a recently proposed positron transport experiment, positrons would be deposited in a fusion plasma by forming a positronium (Ps) beam and passing it through the plasma. Positrons would be deposited as the beam is ionized by plasma ions and electrons. Radial transport of the positrons to the limiter could then be measured by detecting the gamma radiation produced by annihilation of positrons with electrons in the limiter. This would allow measurements of the transport of electron-mass particles and might shed some light on the mechanisms of electron transport in fusion plasmas. In this paper, the deposition and transport of positrons in a tokamak are simulated and the annihilation signal determined for several transport models. Calculations of the expected signals are necessary for the optimal design of a positron transport experiment. There are several mechanisms for the loss of positrons besides transport to the limiter. Annihilation with plasma electrons and reformation of positronium in positron-hydrogen collisions are two such processes. These processes can alter the signal and place restrictions ons on the plasma conditions in which positron transport experiments can be effectively performed

Primary functions of the first Japanese large-scale facility for exposing small animals to radon

International Nuclear Information System (INIS)

Ishimori, Yuu; Tanaka, Hiroshi; Mitsunobu, Fumihiro; Yamaoka, Kiyonori; Kataoka, Takahiro; Sakoda, Akihiro

2010-01-01

The Japan Atomic Energy Agency (JAEA) and Okayama University have carried out the experimental animal study and its related studies since 2007 in order to examine the physiological effects of radon in detail. Thus, a radon test facility for small animals was developed in order to increase the statistical certainty of our animal tests. This paper illustrates the performances of that facility, the first large-scale facility of its types in Japan. The facility has a potential of approximately 150 mouse-scale tests at the same time. The apparatus for exposing small animals to radon has six animal chamber groups each of which consists of five independent cages. Different radon concentrations in each animal chamber group are available. The major functions of the facility controlling radon and avoiding thoron were shown theoretically and experimentally. The relative standard deviation of radon concentration at the highest concentration group was about 5%, although the lower concentration groups seemed to be affected by variations in background radon. (author)

Axial positrons emission tomography: from mouse to human brain imaging

International Nuclear Information System (INIS)

Brard, Emmanuel

2013-01-01

Positrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner's axial extension. These results indicate great perspectives for both clinical and preclinical imaging. (author)

Bone scintigraphy for the investigation of lameness in small animals

International Nuclear Information System (INIS)

Bolln, G.; Franke, C.

2010-01-01

Bone scintigraphy has been used as a helpful method in diagnosing lameness in small animals. It is a sensitive, non-invasive method to evaluate bone lesions and orthopaedic disorders. It provides a functional image of the skeleton and thereby aiding in the localisation and diagnosing of obscure lameness. Compared to human medicine one important difference is the inability of an animal to characterize its pain to the examiner. Another difference is the lacking cooperation of an animal during bone scintigraphy. Before this background are shown on the basis of 5 examples the advantages, the method and the different indication of bone scintigraphy. The technique of this method arrives from a human medicine protocol of a 2-phase-bone-scintigraphy and has to be done under light anaesthesia, to avoid artefacts of movement during acquisitions. The authors are convinced that bone scintigraphy is a very useful and diagnostic method for evaluation of obscure lameness because it can give a quick diagnosis and aimed therapy. Therefore secondary changes and additional costs can be avoided for the animal and its owner. (orig.)

Imaging gene expression in human mesenchymal stem cells: from small to large animals

DEFF Research Database (Denmark)

Willmann, Jürgen K; Paulmurugan, Ramasamy; Rodriguez-Porcel, Martin

2009-01-01

To evaluate the feasibility of reporter gene imaging in implanted human mesenchymal stem cells (MSCs) in porcine myocardium by using clinical positron emission tomography (PET)-computed tomography (CT) scanning.......To evaluate the feasibility of reporter gene imaging in implanted human mesenchymal stem cells (MSCs) in porcine myocardium by using clinical positron emission tomography (PET)-computed tomography (CT) scanning....

A dual layer DOI GSO block detector for a small animal PET

International Nuclear Information System (INIS)

Yamamoto, Seiichi

2009-01-01

For a high resolution animal positron emission tomography (PET), depth-of-interaction (DOI) is a useful method to improve both spatial resolution and sensitivity. Gd 2 SiO 5 (GSO) with different amounts of Ce can provide different decay times and is ideal for DOI detector using pulse shape analysis. Dual layer DOI GSO block detectors using different amounts of Ce were developed for a new animal PET. The DOI GSO block detector employed two types of GSOs; one with 1.5 mol% Ce concentration (decay time: 35 ns) and the other with 0.5 mol% (decay time: 60 ns). These two GSO types were optically coupled in the DOI direction. The sizes of single GSOs were 1.9 mmx1.9 mmx6 mm and 1.9 mmx1.9 mmx9 mm, for 1.5 and 0.5 mol%, respectively. These GSO were arranged by 11x37 matrix and optically coupled to three position sensitive photomultiplier tubes (PSPMTs), where the PSPMTs used were Hamamatsu R8520U-00-C12. Different lengths of reflectors were used between crystals to increase the useful field-of-view (FOV) of the PSPMT and to avoid the dead areas between PSPMTs. With this configuration, almost all islands in a 2-D position histogram corresponding to GSO cells could be separated. The width of the GSO block was 22 mm in the transaxial direction and 74 mm in axial direction with no gaps. Also, two types of GSO of different decay time could be separated using dual integration method for pulse shape analysis. These results indicate that developed block detectors might be useful for a high resolution and high sensitivity animal PET with dual layer DOI detection capability, with no gaps in transaxial or axial directions.

Evaluating performance of a pixel array semiconductor SPECT system for small animal imaging

International Nuclear Information System (INIS)

Kubo, Naoki; Zhao, Songji; Fujiki, Yutaka

2005-01-01

Small animal imaging has recently been focused on basic nuclear medicine. We have designed and built a small animal SPECT imaging system using a semiconductor camera and a newly designed collimator. We assess the performance of this system for small object imaging. We employed an MGC 1500 (Acrorad Co.) camera including a CdTe semiconductor. The pixel size was 1.4 mm/pixel. We designed and produced a parallel-hole collimator with 20-mm hole length. Our SPECT system consisted of a semiconductor camera with the subject holder set on an electric rotating stage controlled by a computer. We compared this system with a conventional small animal SPECT system comprising a SPECT-2000H scanner with four Anger type cameras and pinhole collimators. The count rate linearity for estimation of the scatter was evaluated for a pie-chart phantom containing different concentrations of 99m Tc. We measured the full width half maximum (FWHM) of the 99m Tc SPECT line source along with scatter. The system volume sensitivity was examined using a flood source phantom which was 35 mm long with a 32-mm inside diameter. Additionally, an in vivo myocardial perfusion SPECT study was performed with a rat. With regards to energy resolution, the semiconductor camera (5.6%) was superior to the conventional Anger type camera (9.8%). In the count rate linearity evaluation, the regression lines of the SPECT values were y=0.019x+0.031 (r 2 =0.999) for our system and y=0.018x+0.060 (r 2 =0.997) for the conventional system. Thus, the scatter count using the semiconductor camera was less than that using the conventional camera. FWHMs of our system and the conventional system were 2.9±0.1 and 2.0±0.1 mm, respectively. Moreover, the system volume sensitivity of our system [0.51 kcps/(MBq/ml)/cm] was superior to that of the conventional system [0.44 kcps/(MBq/ml)/cm]. Our system provided clear images of the rat myocardium, sufficient for practical use in small animal imaging. Our SPECT system, utilizing a

A transmission positron microscope and a scanning positron microscope being built at KEK, Japan

International Nuclear Information System (INIS)

Doyama, M.; Inoue, M.; Kogure, Y.; Kurihara, T.; Yagishita, A.; Shidara, T.; Nakahara, K.; Hayashi, Y.; Yoshiie, T.

2001-01-01

This paper reports the plans of positron microscopes being built at KEK (High Energy Accelerator Research Organization), Tsukuba, Japan improving used electron microscopes. The kinetic energies of positron produced by accelerators or by nuclear decays have not a unique value but show a spread over in a wide range. Positron beam will be guided near electron microscopes, a transmission electron microscope (JEM100S) and a scanning electron microscope (JSM25S). Positrons are slowed down by a tungsten foil, accelerated and focused on a nickel sheet. The monochromatic focused beam will be injected into an electron microscope. The focusing of positrons and electrons is achieved by magnetic system of the electron microscopes. Imaging plates are used to record positron images for the transmission electron microscope. (orig.)

Effect of ginseng pretreatment on cerebral glucose metabolism in ischaemic rats using animal positron emission tomography (PET) and [18F]-FDG

Energy Technology Data Exchange (ETDEWEB)

Rye, Choi Seok; Magata, Y.; Saji, H.; Tajima, K.; Kitano, H.; Konishi, J.; Yokoyama, A. [Department of Radiopharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-01 (Japan)

1997-07-01

To investigate the effect of ginseng on damaged brain activity, we evaluated the cerebral metabolic rate of glucose (CMRglc) as a functional index in post-ischaemic rats and compared the results with those obtained after the administration of a ginseng extract. CMRglc was measured using high resolution animal positron emission tomography with {sup 18}F-2-fluoro-2-deoxy-D-glucose ({sup 18}F-FDG). The rats subjected to a 30-min occlusion showed a significant reduction of k3, the rate constant for phosphorylation of {sup 18}F-FDG by hexokinase, compared with the normal value. The ginseng pretreatment prevented the reduction in k3 and CMRglc caused by ischaemia. Although further investigation is needed to elucidate the mechanism of action, ginseng may be useful for prevention and treatment of ischaemia. © 1997 John Wiley & Sons, Ltd.

Positron emission computed tomography

International Nuclear Information System (INIS)

Grover, M.; Schelbert, H.R.

1985-01-01

Regional mycardial blood flow and substrate metabolism can be non-invasively evaluated and quantified with positron emission computed tomography (Positron-CT). Tracers of exogenous glucose utilization and fatty acid metabolism are available and have been extensively tested. Specific tracer kinetic models have been developed or are being tested so that glucose and fatty acid metabolism can be measured quantitatively by Positron-CT. Tracers of amino acid and oxygen metabolism are utilized in Positron-CT studies of the brain and development of such tracers for cardiac studies are in progress. Methods to quantify regional myocardial blood flow are also being developed. Previous studies have demonstrated the ability of Positron-/CT to document myocardial infarction. Experimental and clinical studies have begun to identify metabolic markers of reversibly ischemic myocardium. The potential of Positron-CT to reliably detect potentially salvageable myocardium and, hence, to identify appropriate therapeutic interventions is one of the most exciting applications of the technique

Open-source, small-animal magnetic resonance-guided focused ultrasound system.

Science.gov (United States)

Poorman, Megan E; Chaplin, Vandiver L; Wilkens, Ken; Dockery, Mary D; Giorgio, Todd D; Grissom, William A; Caskey, Charles F

2016-01-01

MR-guided focused ultrasound or high-intensity focused ultrasound (MRgFUS/MRgHIFU) is a non-invasive therapeutic modality with many potential applications in areas such as cancer therapy, drug delivery, and blood-brain barrier opening. However, the large financial costs involved in developing preclinical MRgFUS systems represent a barrier to research groups interested in developing new techniques and applications. We aim to mitigate these challenges by detailing a validated, open-source preclinical MRgFUS system capable of delivering thermal and mechanical FUS in a quantifiable and repeatable manner under real-time MRI guidance. A hardware and software package was developed that includes closed-loop feedback controlled thermometry code and CAD drawings for a therapy table designed for a preclinical MRI scanner. For thermal treatments, the modular software uses a proportional integral derivative controller to maintain a precise focal temperature rise in the target given input from MR phase images obtained concurrently. The software computes the required voltage output and transmits it to a FUS transducer that is embedded in the delivery table within the magnet bore. The delivery table holds the FUS transducer, a small animal and its monitoring equipment, and a transmit/receive RF coil. The transducer is coupled to the animal via a water bath and is translatable in two dimensions from outside the magnet. The transducer is driven by a waveform generator and amplifier controlled by real-time software in Matlab. MR acoustic radiation force imaging is also implemented to confirm the position of the focus for mechanical and thermal treatments. The system was validated in tissue-mimicking phantoms and in vivo during murine tumor hyperthermia treatments. Sonications were successfully controlled over a range of temperatures and thermal doses for up to 20 min with minimal temperature overshoot. MR thermometry was validated with an optical temperature probe, and focus

Positron studies in catalysis research

International Nuclear Information System (INIS)

1994-01-01

During the past eight months, the authors have made progress in several areas relevant to the eventual use of positron techniques in catalysis research. They have come closer to the completion of their positron microscope, and at the same time have performed several studies in their non-microscopic positron spectrometer which should ultimately be applicable to catalysis. The current status of the efforts in each of these areas is summarized in the following sections: Construction of the positron microscope (optical element construction, data collection software, and electronic sub-assemblies); Doppler broadening spectroscopy of metal silicide; Positron lifetime spectroscopy of glassy polymers; and Positron lifetime measurements of pore-sizes in zeolites

22 Na positron source for annihilation positron spectroscopy

International Nuclear Information System (INIS)

Cimpeanu, Catalina; Craciun, L.; Dragulescu, E.; Dudu, D.; Racolta, P. M.; Voiculescu, Dana; Miron, N.

2003-01-01

To extend the nuclear physics applications and to perform the study of vacancy - type defects in metals, semiconductors, polymers etc., we decided to promote positron annihilation techniques. In order to achieve this goal we started a project of dedicated positron sources produced at the IFIN-HH U-120 Cyclotron. We have used the nuclear reaction: 24 Mg(d,α) 22 Na with deuterons of 13 MeV energy. The paper presents the main characteristics of this procedure, as follows: general conditions asked for 22 NaCl sources, reactive chamber and characteristics of Mg target, parameters for the irradiation, radiochemical procedures for separating Na from Mg after the irradiation and geometrical or mechanical requirements for dedicated NaCl source for positron annihilation spectrometry. In the e + lifetime measurements, the e + end - start signals may be obtained from prompt γ -quanta emitted from the NaCl source (1. 275 MeV photons). The 22 NaCl stock solution obtained by radiochemical separation will be kept in quartz sealed ampoules in dry places and will be dropped between the study materials before the use in positron spectrometry. (authors)

Positron annihilation study of graphite, glassy carbon and C60/C70 fullerene

International Nuclear Information System (INIS)

Hasegawa, Masayuki; Kajino, Masahiro; Yamaguchi, Sadae; Iwata, Tadao; Kuramoto, Eiichi; Takenaka, Minoru.

1992-01-01

ACAR (Angular Correlation of Annihilation Radiation) and positron lifetime measurements have been made on, HOPG (Highly Oriented Pyrolytic Graphite), isotropic fine-grained graphite, glassy carbons and C 60 /C 70 powder. HOPG showed marked bimodality along the c-axis and anisotropy in ACAR momentum distribution, which stem from characteristic annihilation between 'interlayer' positrons and π-electrons in graphite. ACAR curves of the isotropic graphite and glassy carbons are even narrower than that of HOPG perpendicular to the c-axis. Positron lifetime of 420 and 390 - 480 psec, much longer than that of 221 psec in HOPG, were observed for the isotropic graphite and glassy carbons respectively, which are due to positron trapping in structural voids in them. Positron lifetime and ACAR width (FWHM) can be well correlated to void sizes (1.7 to 5.0 nm) of glassy carbons which have been determined by small angle neutron (SAN) scattering measurements. ACAR curves and positron lifetime of C 60 /C 70 powder agree well with those of glassy carbons. This shows that positron wave functions extend, as in the voids of glassy carbons, much wider than open spaces of the octahedral interstices of the face-centered cubic (FCC) structure of C 60 crystal and strongly suggests positron trapping in the 'soccer ball' vacancy. Possible positron states in the carbon materials are discussed with a simple model of void volume-trapping. Preliminary results on neutron irradiation damage in HOPG are also presented. (author)

Slow positron applications at slow positron facility of institute of materials structure science, KEK

Science.gov (United States)

Hyodo, Toshio; Mochizuki, Izumi; Wada, Ken; Toge, Nobukazu; Shidara, Tetsuo

2018-05-01

Slow Positron Facility at High Energy Accelerator Research Organization (KEK) is a user dedicated facility with an energy-tunable (0.1 - 35 keV) slow positron beam created by a dedicated ˜ 50 MeV linac. It operates in a short pulse (width 1-12 ns, variable, 5×106 e+/s) and a long pulse (width 1.2 µs, 5×107 e+/s) modes of 50 Hz. High energy positrons from pair creation are moderated by reemission after thermalization in W foils. The reemitted positrons are then electrostatically accelerated to a desired energy up to 35 keV and magnetically transported. A pulse-stretching section (pulse stretcher) is installed in the middle of the beamline. It stretches the slow positron pulse for the experiments where too many positrons annihilating in the sample at the same time has to be avoided. Four experiment stations for TRHEPD (total-reflection high-energy positron diffraction), LEPD (low-energy positron diffraction), Ps- (positronium negative ion), and Ps-TOF (positronium time-of-flight) experiments are connected to the beamline branches, SPF-A3, SPF-A4, SPF-B1 and SPF-B2, respectively. Recent results of these stations are briefly described.

Performance characteristics of a small animal PET camera for molecular imaging

International Nuclear Information System (INIS)

Hastings, D.L.; Reader, A.J.; Julyan, P.J.; Zweit, J.; Jeavons, A.P.; Jones, T.

2007-01-01

The performance of a novel type of animal PET camera, the quad High-Density Avalanche Chamber (HIDAC) was assessed for a non-rotating 16-module system. Spatial resolution was 1.0 mm, and invariant within a standard deviation ≤5%. Absolute sensitivity was 0.95%, and the scatter-background corrected sensitivity was 0.75%. The count rate capability was linear at typical activities used in animal imaging, with a 20% loss at 11.5 MBq. The camera demonstrates small regions of radiotracer uptake with excellent detail in the mouse

The therapeutic lamp: treating small-animal phobias.

Science.gov (United States)

Wrzesien, Maja; Alcañiz, Mariano; Botella, Cristina; Burkhardt, Jean-Marie; Bretón-López, Juana; Ortega, Mario; Brotons, Daniel Beneito

2013-01-01

We all have an irrational fear or two. Some of us get scared by an unexpected visit from a spider in our house; others get nervous when they look down from a high building. Fear is an evolutionary and adaptive function that can promote self-preservation and help us deal with the feared object or situation. However, when this state becomes excessive, it might develop into psychological disorders such as phobias, producing high anxiety and affecting everyday life. The Therapeutic Lamp is an interactive projection-based augmented-reality system for treating small-animal phobias. It aims to increase patient-therapist communication, promote more natural interaction, and improve the patient's engagement in the therapy.

Positron effective mass in silicon

International Nuclear Information System (INIS)

Panda, B.K.; Shan, Y.Y.; Fung, S.; Beling, C.D.

1995-01-01

The positron effective mass in Si is obtained from the first-principles calculations along various crystallographic directions. The effect of electron-positron correlation on the band mass is examined in this work. A positron pseudopotential scheme is worked out to calculate the isotropic band mass without explicitly solving the band energy. The effective mass 1.46m obtained as a sum of band mass and the positron-plasmon interaction compares very well with 1.5m obtained from the positron mobility data

Automated analysis of small animal PET studies through deformable registration to an atlas

International Nuclear Information System (INIS)

Gutierrez, Daniel F.; Zaidi, Habib

2012-01-01

This work aims to develop a methodology for automated atlas-guided analysis of small animal positron emission tomography (PET) data through deformable registration to an anatomical mouse model. A non-rigid registration technique is used to put into correspondence relevant anatomical regions of rodent CT images from combined PET/CT studies to corresponding CT images of the Digimouse anatomical mouse model. The latter provides a pre-segmented atlas consisting of 21 anatomical regions suitable for automated quantitative analysis. Image registration is performed using a package based on the Insight Toolkit allowing the implementation of various image registration algorithms. The optimal parameters obtained for deformable registration were applied to simulated and experimental mouse PET/CT studies. The accuracy of the image registration procedure was assessed by segmenting mouse CT images into seven regions: brain, lungs, heart, kidneys, bladder, skeleton and the rest of the body. This was accomplished prior to image registration using a semi-automated algorithm. Each mouse segmentation was transformed using the parameters obtained during CT to CT image registration. The resulting segmentation was compared with the original Digimouse atlas to quantify image registration accuracy using established metrics such as the Dice coefficient and Hausdorff distance. PET images were then transformed using the same technique and automated quantitative analysis of tracer uptake performed. The Dice coefficient and Hausdorff distance show fair to excellent agreement and a mean registration mismatch distance of about 6 mm. The results demonstrate good quantification accuracy in most of the regions, especially the brain, but not in the bladder, as expected. Normalized mean activity estimates were preserved between the reference and automated quantification techniques with relative errors below 10 % in most of the organs considered. The proposed automated quantification technique is

Cone Beam Micro-CT System for Small Animal Imaging and Performance Evaluation

Directory of Open Access Journals (Sweden)

Shouping Zhu

2009-01-01

in this paper. Experimental results show that the system is suitable for small animal imaging and is adequate to provide high-resolution anatomic information for bioluminescence tomography to build a dual modality system.

Generation of a high-brightness pulsed positron beam for the Munich scanning positron microscope

Energy Technology Data Exchange (ETDEWEB)

Piochacz, Christian

2009-11-20

Within the present work the prerequisites for the operation of the Munich scanning positron microscope (SPM) at the high intense neutron induced positron source Munich (NEPOMUC) were established. This was accomplished in two steps: Firstly, a re-moderation device was installed at the positron beam facility NEPOMUC, which enhances the brightness of the positron beam for all connected experiments. The second step was the design, set up and initial operation of the SPM interface for the high efficient conversion of the continuous beam into a bunched beam. The in-pile positron source NEPOMUC creates a positron beam with a diameter of typically 7 mm, a kinetic energy of 1 keV and an energy spread of 50 eV. The NEPOMUC re-moderator generates from this beam a low energy positron beam (20 - 200 eV) with a diameter of less than 2 mm and an energy spread well below 2.5 eV. This was achieved with an excellent total efficiency of 6.55{+-}0.25 %. The re-moderator was not only the rst step to implement the SPM at NEPOMUc, it enables also the operation of the pulsed low energy positron beam system (PLEPS). Within the present work, at this spectrometer rst positron lifetime measurements were performed, which revealed the defect types of an ion irradiated uranium molybdenum alloy. Moreover, the instruments which were already connected to the positron beam facility bene ts considerably of the high brightness enhancement. In the new SPM interface an additional re-moderation stage enhances the brightness of the beam even more and will enable positron lifetime measurements at the SPM with a lateral resolution below 1 {mu}m. The efficiency of the re-moderation process in this second stage was 24.5{+-}4.5 %. In order to convert high efficiently the continuous positron beam into a pulsed beam with a repetition rate of 50 MHz and a pulse duration of less than 50 ps, a sub-harmonic pre-bucher was combined with two sine wave bunchers. Furthermore, the additional re-moderation stage of the

Generation of a high-brightness pulsed positron beam for the Munich scanning positron microscope

International Nuclear Information System (INIS)

Piochacz, Christian

2009-01-01

Within the present work the prerequisites for the operation of the Munich scanning positron microscope (SPM) at the high intense neutron induced positron source Munich (NEPOMUC) were established. This was accomplished in two steps: Firstly, a re-moderation device was installed at the positron beam facility NEPOMUC, which enhances the brightness of the positron beam for all connected experiments. The second step was the design, set up and initial operation of the SPM interface for the high efficient conversion of the continuous beam into a bunched beam. The in-pile positron source NEPOMUC creates a positron beam with a diameter of typically 7 mm, a kinetic energy of 1 keV and an energy spread of 50 eV. The NEPOMUC re-moderator generates from this beam a low energy positron beam (20 - 200 eV) with a diameter of less than 2 mm and an energy spread well below 2.5 eV. This was achieved with an excellent total efficiency of 6.55±0.25 %. The re-moderator was not only the rst step to implement the SPM at NEPOMUc, it enables also the operation of the pulsed low energy positron beam system (PLEPS). Within the present work, at this spectrometer rst positron lifetime measurements were performed, which revealed the defect types of an ion irradiated uranium molybdenum alloy. Moreover, the instruments which were already connected to the positron beam facility bene ts considerably of the high brightness enhancement. In the new SPM interface an additional re-moderation stage enhances the brightness of the beam even more and will enable positron lifetime measurements at the SPM with a lateral resolution below 1 μm. The efficiency of the re-moderation process in this second stage was 24.5±4.5 %. In order to convert high efficiently the continuous positron beam into a pulsed beam with a repetition rate of 50 MHz and a pulse duration of less than 50 ps, a sub-harmonic pre-bucher was combined with two sine wave bunchers. Furthermore, the additional re-moderation stage of the SPM

Li-doped MgO as catalysts for oxidative coupling of methane: A positron annihilation study

Science.gov (United States)

Dai, G. H.; Yan, Q. J.; Wang, Y.; Liu, Q. S.

1991-08-01

Magnesium oxides intentionally doped with lithium (with a maximum Li content of 40 tool%) for use as catalysts for oxidative coupling of methane were characterized by means of positron annihilation. The positron lifetime spectra, which could be reasonably well interpreted within the framework of the well-known trapping model, depend on the amount of Li doping of the MgO suggesting that positrons are trapped at dispersed small Li 2CO 3 precipitates. Very similar dependencies on lithium doping of the C 2 selectivity and the positron trapping rate ϰ imply an intimate relationship between the concentration of [Li] 0-centers (also referred to as [Li +O -] centers) and the selective activity of Li/MgO during catalytic reactions.

Positron sources for electron-positron colliders application to the ILC and CLIC

CERN Multimedia

CERN. Geneva

2008-01-01

The increased demanding qualities for positron sources dedicated to e+e- colliders pushed on investigations oriented on new kinds of e+ sources. The different kinds of positron sources polarized and no polarized are considered. Their main features (intensity, emittance) are described and analysed. Comparison between the different sources is worked out. The characteristics of the positron beam available in the collision point are greatly depending on the capture device and on the positron accelerator. Different kinds of capture systems are considered and their qualities, compared. Intense positron sources which are necessary for the colliders require intense incident beams (electrons or photons). The large number of pairs created in the targets leads to important energy deposition and so, thermal heating, which associated to temperature gradients provoke mechanical stresses often destructive. Moreover, the important Coulomb collisions, can affect the atomic structure in crystal targets and the radiation resist...

High current pulsed positron microprobe

International Nuclear Information System (INIS)

Howell, R.H.; Stoeffl, W.; Kumar, A.; Sterne, P.A.; Cowan, T.E.; Hartley, J.

1997-01-01

We are developing a low energy, microscopically focused, pulsed positron beam for defect analysis by positron lifetime spectroscopy to provide a new defect analysis capability at the 10 10 e + s -l beam at the Lawrence Livermore National Laboratory electron linac. When completed, the pulsed positron microprobe will enable defect specific, 3-dimensional maps of defect concentrations with sub-micron resolution of defect location. By coupling these data with first principles calculations of defect specific positron lifetimes and positron implantation profiles we will both map the identity and concentration of defect distributions

Efficient Cryosolid Positron Moderators

Science.gov (United States)

2012-08-01

table layout Figure 21 shows the integration of the IR spectroscopy optics with the positron Moderation and Annihilation vacuum chambers on the...Characterization of Cryogenic Moderators The application of Matrix Isolation Spectroscopy (MIS) to characterizing cryogenic solid positron ...Matrix Isolation Spectroscopy capability into our Positron Moderation apparatus, which enables spectroscopic characterization of the cryogenic

Positron annihilation in a metal-oxide semiconductor studied by using a pulsed monoenergetic positron beam

Science.gov (United States)

Uedono, A.; Wei, L.; Tanigawa, S.; Suzuki, R.; Ohgaki, H.; Mikado, T.; Ohji, Y.

1993-12-01

The positron annihilation in a metal-oxide semiconductor was studied by using a pulsed monoenergetic positron beam. Lifetime spectra of positrons were measured as a function of incident positron energy for a polycrystalline Si(100 nm)/SiO2(400 nm)/Si specimen. Applying a gate voltage between the polycrystalline Si film and the Si substrate, positrons implanted into the specimen were accumulated at the SiO2/Si interface. From the measurements, it was found that the annihilation probability of ortho-positronium (ortho-Ps) drastically decreased at the SiO2/Si interface. The observed inhibition of the Ps formation was attributed to an interaction between positrons and defects at the SiO2/Si interface.

The performance of silicon detectors for the SiliPET project: A small animal PET scanner based on stacks of silicon detectors

International Nuclear Information System (INIS)

Auricchio, Natalia; Domenico, Giovanni di; Zavattini, Guido; Milano, Luciano; Malaguti, Roberto

2011-01-01

We propose a new scanner for small animal Positron Emission Tomography (PET) based on stacks of double sided silicon detectors. Each stack is made of 40 planar detectors with dimension 60x60x1 mm 3 and 128 orthogonal strips on both sides to read the two coordinates of interaction, the third being the detector number in the stack. Multiple interactions in a stack are discarded by an exclusive OR applied between each detector plane of a stack. In this way we achieve a precise determination of the interaction point of the two 511 keV photons. The reduced dimensions of the scanner also improve the solid angle coverage resulting in a high sensitivity. Preliminary results were obtained with MEGA prototype tracker (11 double sided Si detector layers), divided into two stacks 2 cm apart made of, respectively, 5 and 6 prototype layers, placing a small spherical 22 Na source in different positions. We report on the results, spatial resolution, imaging and timing performances obtained with double sided silicon detectors, manufactured by ITC-FBK, having an active area of 3x3 cm 2 , thickness of 1 mm and a strip pitch of 500μm. Two different strip widths of 300 and 200μm equipped with 64 orthogonal p and n strips on opposite sides were read out with the VATAGP2.5 ASIC, a 128-channel 'general purpose' charge sensitive amplifier.

Polarized positrons in Jefferson lab electron ion collider (JLEIC)

Science.gov (United States)

Lin, Fanglei; Grames, Joe; Guo, Jiquan; Morozov, Vasiliy; Zhang, Yuhong

2018-05-01

The Jefferson Lab Electron Ion Collider (JLEIC) is designed to provide collisions of electron and ion beams with high luminosity and high polarization to reach new frontier in exploration of nuclear structure. The luminosity, exceeding 1033 cm-2s-1 in a broad range of the center-of-mass (CM) energy and maximum luminosity above 1034 cm-2s-1, is achieved by high-rate collisions of short small-emittance low-charge bunches with proper cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) and electron can be easily preserved, manipulated and maintained by taking advantage of the unique figure-8 shape rings. With a growing physics interest, polarized positron-ion collisions are considered to be carried out in the JLEIC to offer an additional probe to study the substructure of nucleons and nuclei. However, the creation of polarized positrons with sufficient intensity is particularly challenging. We propose a dedicated scheme to generate polarized positrons. Rather than trying to accumulate "hot" positrons after conversion, we will accumulate "cold" electrons before conversion. Charge accumulation additionally provides a novel means to convert high repetition rate (>100 MHz) electron beam from the gun to a low repetition rate (<100 MHz) positron beam for broad applications. In this paper, we will address the scheme, provide preliminary estimated parameters and explain the key areas to reach the desired goal.

Design and Characteristics of a Multichannel Front-End ASIC Using Current-Mode CSA for Small-Animal PET Imaging.

Science.gov (United States)

Ollivier-Henry, N; Wu Gao; Xiaochao Fang; Mbow, N A; Brasse, D; Humbert, B; Hu-Guo, C; Colledani, C; Yann Hu

2011-02-01

This paper presents the design and characteristics of a front-end readout application-specific integrated circuit (ASIC) dedicated to a multichannel-plate photodetector coupled to LYSO scintillating crystals. In our configuration, the crystals are oriented in the axial direction readout on both sides by individual photodetector channels allowing the spatial resolution and the detection efficiency to be independent of each other. Both energy signals and timing triggers from the photodetectors are required to be read out by the front-end ASIC. A current-mode charge-sensitive amplifier is proposed for this application. This paper presents performance characteristics of a 10-channel prototype chip designed and fabricated in a 0.35-μm complementary metal-oxide semiconductor process. The main results of simulations and measurements are presented and discussed. The gain of the chip is 13.1 mV/pC while the peak time of a CR-RC pulse shaper is 280 ns. The signal-to-noise ratio is 39 dB and the rms noise is 300 μV/√(Hz). The nonlinearity is less than 3% and the crosstalk is about 0.2%. The power dissipation is less than 15 mW/channel. This prototype will be extended to a 64-channel circuit with integrated time-to-digital converter and analog-to-digital converter together for a high-sensitive small-animal positron emission tomography imaging system.

Fully automated intrinsic respiratory and cardiac gating for small animal CT

Energy Technology Data Exchange (ETDEWEB)

Kuntz, J; Baeuerle, T; Semmler, W; Bartling, S H [Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg (Germany); Dinkel, J [Department of Radiology, German Cancer Research Center, Heidelberg (Germany); Zwick, S [Department of Diagnostic Radiology, Medical Physics, Freiburg University (Germany); Grasruck, M [Siemens Healthcare, Forchheim (Germany); Kiessling, F [Chair of Experimental Molecular Imaging, RWTH-Aachen University, Medical Faculty, Aachen (Germany); Gupta, R [Department of Radiology, Massachusetts General Hospital, Boston, MA (United States)], E-mail: j.kuntz@dkfz.de

2010-04-07

A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-corrected still images as well as to generate four-dimensional (4D) datasets representing the cardiac and pulmonary anatomy of free-breathing animals without the use of electrocardiogram (ECG) or respiratory sensors. Variation analysis of projections from several rotations is used to place a region of interest (ROI) on the diaphragm. The ROI is cranially extended to include the heart. The centre of mass (COM) variation within this ROI, the filtered frequency response and the local maxima are used to derive a binary motion-gating parameter for phase-sensitive gated reconstruction. This algorithm was implemented on a flat-panel-based cone-beam CT scanner and evaluated using a moving phantom and animal scans (seven rats and eight mice). Volumes were determined using a semiautomatic segmentation. In all cases robust gating signals could be obtained. The maximum volume error in phantom studies was less than 6%. By utilizing extrinsic gating via externally placed cardiac and respiratory sensors, the functional parameters (e.g. cardiac ejection fraction) and image quality were equivalent to this current gold standard. This algorithm obviates the necessity of both gating hardware and user interaction. The simplicity of the proposed algorithm enables adoption in a wide range of small animal cone-beam CT scanners.

22 Na positron source for annihilation positron spectroscopy

International Nuclear Information System (INIS)

Cimpeanu, Catalina; Craciun, L.; Dragulescu, E.; Dudu, D.; Racolta, P.M.; Voiculescu, Dana; Miron, N.

2002-01-01

To extend the nuclear physics applications and to perform the study of vacancy - type defects in metals, semiconductors, polymers etc., we decided to promote positron annihilation techniques. In order to achieve this goal we started a project of dedicated positron sources produced at the IFIN-HH U-120 Cyclotron. We have used the nuclear reaction 24 Mg(d,α) 22 Na and deuterons of 13 MeV energy. The paper presents the main steps of this procedure like: general conditions required for 22 NaCl sources, reactive chamber and characteristics of Mg target, parameters for the irradiation, radiochemical procedures to separate Na from Mg after the irradiation and geometrical or mechanical requirements for dedicated NaCl source for positron annihilation spectrometry. In the e + lifetime measurements the e + 'death - stop' signals are always provided by γ - quanta generated by the e + e - annihilation and the 'birth - start' signals may be obtained from 'prompt' γ - quanta emitted from the NaCl source (the 1.275 MeV photons). The 22 NaCl stock solution obtained by radiochemical separation will be kept in the sealed quartz vials in dry places and will be dropped between the studied materials before use in positron spectrometry. (authors)

Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield

Energy Technology Data Exchange (ETDEWEB)

Corde, Sebastien [SLAC National Accelerator Lab., Menlo Park, CA (United States); Adli, E. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. of Oslo, Oslo (Norway); Allen, J. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); An, W. [Univ. of California, Los Angeles, CA (United States); Clarke, C. I. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Delahaye, J. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Frederico, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gessner, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Green, S. Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hogan, M. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Joshi, C. [Univ. of California, Los Angeles, CA (United States); Lipkowitz, N. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lu, W. [Tsinghua Univ., Beijing (China); Marsh, K. A. [Univ. of California, Los Angeles, CA (United States); Mori, W. B. [Univ. of California, Los Angeles, CA (United States); Schmeltz, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Vafaei-Najafabadi, N. [Univ. of California, Los Angeles, CA (United States); Walz, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Yakimenko, V. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Yocky, G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Clayton, C. E. [Univ. of California, Los Angeles, CA (United States)

2015-08-26

New accelerator concepts must be developed to make future particle colliders more compact and affordable. The Plasma Wakefield Accelerator (PWFA) is one such concept, where the electric field of a plasma wake excited by a charged-particle bunch is used to accelerate a trailing bunch of particles. To apply plasma acceleration to particle colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas1. While substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch 2, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFA where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered – self-loaded – so that about a billion positrons gain five gigaelectronvolts (GeV) of energy with a narrow energy spread in a distance of just 1.3 meters. They extract about 30% of the wake’s energy and form a spectrally distinct bunch with as low as a 1.8% r.m.s. energy spread. This demonstrated ability of positron-driven plasma wakes to efficiently accelerate a significant number of positrons with a small energy spread may overcome the long-standing challenge of positron acceleration in plasma-based accelerators.

An automated robot arm system for small animal tissue biopsy under dual-image modality

International Nuclear Information System (INIS)

Huang, Y.H.; Wu, T.H.; Lin, M.H.; Yang, C.C.; Guo, W.Y.; Wang, Z.J.; Chen, C.L.; Lee, J.S.

2006-01-01

The ability to non-invasively monitor cell biology in vivo is one of the most important goals of molecular imaging. Imaging procedures could be inter-subject performed repeatedly at different investigating stages; thereby need not sacrifice small animals during the entire study period. Thus, the ultimate goal of this study was to design a stereotactic image-guided system for small animals and integrated it with an automatic robot arm for in vivo tissue biopsy analysis. The system was composed of three main parts, including one small animal stereotactic frame, one imaging-fusion software and an automatic robot arm system. The system has been thoroughly evaluated with three components; the robot position accuracy was 0.05±0.02 mm, the image registration accuracy was 0.37±0.18 mm and the system integration was satisfactorily within 1.20±0.39 mm of error. From these results, the system demonstrated sufficient accuracy to guide the micro-injector from the planned delivery routes into practice. The entire system accuracy was limited by the image fusion and orientation procedures, due to its nature of the blurred PET imaging obtained from the small objects. The primary improvement is to acquire as higher resolution as possible the fused imaging for localizing the targets in the future

Performance of the first Japanese large-scale facility for radon inhalation experiments with small animals

International Nuclear Information System (INIS)

Ishimori, Y.; Mitsunobu, F.; Yamaoka, K.; Tanaka, H.; Kataoka, T.; Sakoda, A.

2011-01-01

A radon test facility for small animals was developed in order to increase the statistical validity of differences of the biological response in various radon environments. This paper illustrates the performances of that facility, the first large-scale facility of its kind in Japan. The facility has a capability to conduct approximately 150 mouse-scale tests at the same time. The apparatus for exposing small animals to radon has six animal chamber groups with five independent cages each. Different radon concentrations in each animal chamber group are available. Because the first target of this study is to examine the in vivo behaviour of radon and its effects, the major functions to control radon and to eliminate thoron were examined experimentally. Additionally, radon progeny concentrations and their particle size distributions in the cages were also examined experimentally to be considered in future projects. (authors)

Positron Beam Characteristics at NEPOMUC Upgrade

Science.gov (United States)

Hugenschmidt, C.; Ceeh, H.; Gigl, T.; Lippert, F.; Piochacz, C.; Reiner, M.; Schreckenbach, K.; Vohburger, S.; Weber, J.; Zimnik, S.

2014-04-01

In 2012, the new neutron induced positron source NEPOMUC upgrade was put into operation at FRMII. Major changes have been made to the source which consists of a neutron-γ-converter out of Cd and a Pt foil structure for electron positron pair production and positron moderation. The new design leads to an improvement of both intensity and brightness of the mono-energetic positron beam. In addition, the application of highly enriched 113Cd as neutron-γ-converter extends the lifetime of the positron source to 25 years. A new switching and remoderation device has been installed in order to allow toggling from the high-intensity primary beam to a brightness enhanced remoderated positron beam. At present, an intensity of more than 109 moderated positrons per second is achieved at NEPOMUC upgrade. The main characteristics are presented which comprise positron yield and beam profile of both the primary and the remoderated positron beam.

Veterinarians' perceptions of behaviour support in small-animal practice.

Science.gov (United States)

Roshier, A L; McBride, E A

2013-03-09

Veterinarians are professionals considered to be at the forefront of animal welfare, including behaviour medicine. However, concerns raised, both within the profession and without, highlight that the support offered is not optimal, due to deficiencies in veterinary training, which focuses on physical aspects and overlooks psychological aspects. This preliminary study explored the experiences and perceptions of six veterinarians (three male, three female, age range: 23-55 years) in two UK small-animal practices. Seventeen annual booster consultations were videoed and conversations thematically analysed for welfare topics discussed. Both veterinarians and clients completed questionnaires to gather demographic information and perspectives. All veterinarians recognised behaviour as a component of their caseload, and acknowledged that clients expected them to provide behaviour support. Veterinarians varied in their experiences of and confidence in providing behaviour support. Five felt unable to meet client expectations; four did not feel their training had prepared them sufficiently. Only one provided dedicated behaviour consultations, the others referred cases. All provided suggestions for behaviour skills needed for new veterinary graduates. The study has afforded an insight into the experiences of a small opportunistic sample of veterinarians. The data indicated important limitations regarding time available in general consultations to discuss behaviour concerns, and practitioner knowledge and skill in detection, anamnesis, assessment and provision of appropriate behaviour information. Suggestions for veterinary training in behaviour are provided.

Micro tomography prototype by positron emission. Spatial resolution and metabolic studies;Prototipo de microtomografo por emision de positrones. Resolucion espacial y estudios metabolicos

Energy Technology Data Exchange (ETDEWEB)

Alva S, H.; Murrieta, T.; Ruiz T, C.; Brandan, M. E.; Martinez D, A.; Rodriguez V, M., E-mail: halva@fisica.unam.m [UNAM, Instituto de Fisica, Circuito de la Investigacion Cientifica s/n, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

2010-07-01

During the past 4 years, the Medical Physics and Dosimetry Group at the Physics Institute, UNAM, has developed a positron emission tomography prototype for small-animal imaging (micro PET). The system is composed of pix elated, cerium-doped lutetium yttrium oxy orthosilicate scintillation crystal arrays coupled to position-sensitive photomultiplier tubes. Detector electronic signals are processed by nuclear instrumentation modules and are digitized by a multichannel data acquisition board. The tomographic reconstruction is performed by filtered backprojection from a set of distortion- and nonuniformity- corrected projections taken at different angles. In this work, the reconstructed spatial resolution was evaluated from the line spread function with a mean value of 2.36 +- 0.44 mm. In addition, the first metabolic studies of 30 g, healthy mice, injected with {sup 1}8{sup F} labeled fluorodeoxyglucose and sodium fluoride are reported. They display normal glucose uptake and skeletal structure, respectively. The micro PET can be a useful tool for radiation detector physics research and its applications in nuclear medicine. (Author)

Positron emission tomography

International Nuclear Information System (INIS)

Wienhard, K.; Heiss, W.D.

1984-01-01

The principles and selected clinical applications of positron emission tomography are described. In this technique a chemical compound is labeled with a positron emitting isotope and its biochemical pathway is traced by coincidence detection of the two annihilation photons. The application of the techniques of computed tomography allows to reconstruct the spatial distribution of the radioactivity within a subject. The 18 F-deoxyglucose method for quantitative measurement of local glucose metabolism is discussed in order to illustrate the possibilities of positron emission tomography to record physiological processes in vivo. (orig.) [de

Application of mathematical removal of positron range blurring in positron emission tomography

International Nuclear Information System (INIS)

Haber, S.F.; Derenzo, S.E.; Uber, D.

1990-01-01

The range of positrons in tissue is an important limitation to the ultimate spatial resolution achievable in positron emission tomography. In this work the authors have applied a Fourier deconvolution technique to remove range blurring in images taken by the Donner 600-crystal positron tomograph. Using phantom data, the authors have found significant improvement in the image quality and the FWHM for both 68 Ga and 82 Rb. These were successfully corrected so that the images and FWHM almost matched those of 18 F which has negligible positron range. However, statistical noise was increased by the deconvolution process and it was not practical to recover the full spatial resolution of the tomograph

Dynamic Positron Emission Tomography [PET] in Man Using Small Bismuth Germanate Crystals

Science.gov (United States)

Derenzo, S. E.; Budinger, T. F.; Huesman, R. H.; Cahoon, J. L.

1982-04-01

Primary considerations for the design of positron emission tomographs for medical studies in humans are the need for high imaging sensitivity, whole organ coverage, good spatial resolution, high maximum data rates, adequate spatial sampling with minimum mechanical motion, shielding against out of plane activity, pulse height discrimination against scattered photons, and timing discrimination against accidental coincidences. We discuss the choice of detectors, sampling motion, shielding, and electronics to meet these objectives.

Positron Annihilation in Insulating Materials

International Nuclear Information System (INIS)

Asoka-Kumar, P; Sterne, PA

2002-01-01

We describe positron results from a wide range of insulating materials. We have completed positron experiments on a range of zeolite-y samples, KDP crystals, alkali halides and laser damaged SiO 2 . Present theoretical understanding of positron behavior in insulators is incomplete and our combined theoretical and experimental approach is aimed at developing a predictive understanding of positrons and positronium annihilation characteristics in insulators. Results from alkali halides and alkaline-earth halides show that positrons annihilate with only the halide ions, with no apparent contribution from the alkali or alkaline-earth cations. This contradicts the results of our existing theory for metals, which predicts roughly equal annihilation contributions from cation and anion. We also present result obtained using Munich positron microprobe on laser damaged SiO 2 samples

''Heavy light bullets'' in electron-positron plasma

International Nuclear Information System (INIS)

Berezhiani, V.I.; Mahajan, S.M.

1995-03-01

The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of ''heavy light bullets''; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching. (author). 24 refs, 12 figs

Management and Level of Asian small-clawed otter (Aonyx cinereus Illinger, 1815 as Display Animal in Indonesia Conservation Institution

Directory of Open Access Journals (Sweden)

Ulfa Hansyari Ar-Rasyid

2017-09-01

Full Text Available Education and breeding become main reasons for asian small-clawed otter placement as display animal in zoo. Proper management is needed to maintain asian small-clawed otter welfare. This research objectives were to examine and assess asian small-clawed otter welfare in three Indonesia zoos. The study was conducted from December 2016 to February 2017 in Bandung Zoo, Ragunan Zoo and Ocean Dream Samudra Ancol. The methods of this research were literature review, interview and field observation. Data were analyzed using the suitability of management and animal welfare assessment. The result showed that there were three main management activities conducted at the three study locations, i.e., nutrition, housing, and health management. Bandung Zoo achieved the lowest score of asian small-clawed otter welfare (45,24% compared to Ragunan Zoo (62,24% and Ocean Dream Samudra (65,90%. Asian small-clawed otter welfare in three institutions were relatively low to fair category, this was due to the unfilled quality of food and water i.e.,  the type, amount, feeding frequency, diet and preparing of food; the unavailability of suitable and favorable environmental conditions; the care facilities provided could not ensure the health of animal; the appearance of abnormal behavior that affected the growth and breeding of animal; and animal had no freedom to behave as in their natural habitat. Keywords: animal display, animal welfare, Asian small-clawed otter, zoo 

Positron spectroscopy as an analytical tool in material sciences

International Nuclear Information System (INIS)

Pujari, P.K.

2010-01-01

Full text: Positron annihilation spectroscopy has emerged as a powerful tool in material sciences due to its ability to provide information about the electron momentum distribution and electron density in a given medium. These features help in identifying altered state of electronic rearrangements as one encounters in phase transitions. In addition, positrons prefer regions of lower electron density such as open volume defects i.e. vacancies or vacancy clusters in metals, alloys and semiconductors or free-volumes in molecular solids. Its sensitivity to defects is extremely high e.g. it can detect as small a defect as monovacancy to concentration as low as parts per million(ppm). Innovative nuclear instrumentation has helped in getting chemical specificity at the annihilation site. For example, precipitates, embedded, nanoparticles or element decorated vacancies can now be easily identified. This presentation is structured to introduce the technique and provide a global perspective on area of applications. Specific examples on defect characterization, nanostructure-property correlations in polymers, advantages of elemental specificity by indexing the core electron momentum will be given. In addition, slow positron beam based studies on nanostructured materials as well as particle accelerator based positron spectroscopy for volumetric assay of defects in large engineering samples will be presented

Experimental validation of gallium production and isotope-dependent positron range correction in PET

Energy Technology Data Exchange (ETDEWEB)

Fraile, L.M., E-mail: lmfraile@ucm.es [Grupo de Física Nuclear, Dpto. Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Herraiz, J.L.; Udías, J.M.; Cal-González, J.; Corzo, P.M.G.; España, S.; Herranz, E.; Pérez-Liva, M.; Picado, E.; Vicente, E. [Grupo de Física Nuclear, Dpto. Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Muñoz-Martín, A. [Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Vaquero, J.J. [Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid (Spain)

2016-04-01

Positron range (PR) is one of the important factors that limit the spatial resolution of positron emission tomography (PET) preclinical images. Its blurring effect can be corrected to a large extent if the appropriate method is used during the image reconstruction. Nevertheless, this correction requires an accurate modelling of the PR for the particular radionuclide and materials in the sample under study. In this work we investigate PET imaging with {sup 68}Ga and {sup 66}Ga radioisotopes, which have a large PR and are being used in many preclinical and clinical PET studies. We produced a {sup 68}Ga and {sup 66}Ga phantom on a natural zinc target through (p,n) reactions using the 9-MeV proton beam delivered by the 5-MV CMAM tandetron accelerator. The phantom was imaged in an ARGUS small animal PET/CT scanner and reconstructed with a fully 3D iterative algorithm, with and without PR corrections. The reconstructed images at different time frames show significant improvement in spatial resolution when the appropriate PR is applied for each frame, by taking into account the relative amount of each isotope in the sample. With these results we validate our previously proposed PR correction method for isotopes with large PR. Additionally, we explore the feasibility of PET imaging with {sup 68}Ga and {sup 66}Ga radioisotopes in proton therapy.

A new small-animal model for the study of acquired heterotopic ossification after hip surgery.

Science.gov (United States)

Anthonissen, Joris; Ossendorf, Christian; Hock, Johanna Lisa; Ritz, Ulrike; Hofmann, Alexander; Rommens, Pol Maria

2015-01-01

Heterotopic ossification (HO)--the formation of bone in soft tissues--is a frequent problem after surgery of the hip and pelvis, but little is known about its underlying pathogenic mechanisms. It is vital to study the underlying pathogenesis in animal models to develop and evaluate new prophylactic regimens directed against HO. However, previously developed small-animal models for the study of HO imitate neither surgery nor trauma-mechanisms that potentially cause HO. Hence, the goal of this study was to develop a novel small-animal model imitating hip surgery that can reliably produce HO. Twenty male Wistar rats were subjected to surgery of the right hip during which the femoral canal was reamed in three steps up to 2 mm, and a muscle lesion was made. Twelve weeks after surgery, the amount of heterotopic bone was assessed using micro-computed tomography. Eighteen of 20 animals showed HO around the hip 12 weeks after surgery. The amount of heterotopic bone varied from very small particles up to near ankylosis. A rat model of hip/pelvic surgery that does not use exogenous osteogenic stimulus and can reliably produce HO was developed.

Applications of slow positrons to cancer research: Search for selectivity of positron annihilation to skin cancer

International Nuclear Information System (INIS)

Jean, Y.C.; Li Ying; Liu Gaung; Chen, Hongmin; Zhang Junjie; Gadzia, Joseph E.

2006-01-01

Slow positrons and positron annihilation spectroscopy (PAS) have been applied to medical research in searching for positron annihilation selectivity to cancer cells. We report the results of positron lifetime and Doppler broadening energy spectroscopies in human skin samples with and without cancer as a function of positron incident energy (up to 8 μm depth) and found that the positronium annihilates at a significantly lower rate and forms at a lower probability in the samples having either basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) than in the normal skin. The significant selectivity of positron annihilation to skin cancer may open a new research area of developing positron annihilation spectroscopy as a novel medical tool to detect cancer formation externally and non-invasively at the early stages

Applications of slow positrons to cancer research: Search for selectivity of positron annihilation to skin cancer

Energy Technology Data Exchange (ETDEWEB)

Jean, Y.C. [Department of Chemistry, University of Missouri-Kansas City, 205 Spenscer Chemistry Building, 5009 Rockhill Road, Kansas City, MO 64110 (United States)]. E-mail: jeany@umkc.edu; Li Ying [Department of Chemistry, University of Missouri-Kansas City, 205 Spenscer Chemistry Building, 5009 Rockhill Road, Kansas City, MO 64110 (United States); Liu Gaung [Department of Chemistry, University of Missouri-Kansas City, 205 Spenscer Chemistry Building, 5009 Rockhill Road, Kansas City, MO 64110 (United States); Chen, Hongmin [Department of Chemistry, University of Missouri-Kansas City, 205 Spenscer Chemistry Building, 5009 Rockhill Road, Kansas City, MO 64110 (United States); Zhang Junjie [Department of Chemistry, University of Missouri-Kansas City, 205 Spenscer Chemistry Building, 5009 Rockhill Road, Kansas City, MO 64110 (United States); Gadzia, Joseph E. [Dermatology, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66103 (United States); Kansas Medical Clinic, Topeka, KS 66614 (United States)

2006-02-28

Slow positrons and positron annihilation spectroscopy (PAS) have been applied to medical research in searching for positron annihilation selectivity to cancer cells. We report the results of positron lifetime and Doppler broadening energy spectroscopies in human skin samples with and without cancer as a function of positron incident energy (up to 8 {mu}m depth) and found that the positronium annihilates at a significantly lower rate and forms at a lower probability in the samples having either basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) than in the normal skin. The significant selectivity of positron annihilation to skin cancer may open a new research area of developing positron annihilation spectroscopy as a novel medical tool to detect cancer formation externally and non-invasively at the early stages.

Fundamental image quality limits for microcomputed tomography in small animals

International Nuclear Information System (INIS)

Ford, N.L.; Thornton, M.M.; Holdsworth, D.W.

2003-01-01

Small-animal imaging has become increasingly more important as transgenic and knockout mice are produced to model human diseases. One imaging technique that has emerged is microcomputed tomography (micro-CT). For live-animal imaging, the precision in the images will be determined by the x-ray dose given to the animal. As a result, we propose a simple method to predict the noise performance of an x-ray micro-CT system as a function of dose and image resolution. An ideal, quantum-noise limited micro-CT scanner, assumed to have perfect resolution and ideal efficiency, was modeled. Using a simplified model, the coefficient of variation (COV) of the linear attenuation coefficient was calculated for a range of entrance doses and isotropic voxel sizes. COV calculations were performed for the ideal case and with simulated imperfections in efficiency and resolution. Our model was validated in phantom studies and mouse images were acquired with a specimen scanner to illustrate the results. A simplified model of noise propagation in the case of isotropic resolution indicates that the COV in the linear attenuation coefficient is proportional to (dose) -1/2 and to the (isotropic voxel size) -2 in the reconstructed volume. Therefore an improvement in the precision can be achieved only by increasing the isotropic voxel size (thereby decreasing the resolution of the image) or by increasing the x-ray dose. For the ideal scanner, a COV of 1% in the linear attenuation coefficient for an image of a mouse exposed to 0.25 Gy is obtained with a minimum isotropic voxel size of 135 μm. However, the same COV is achieved at a dose of 5.0 Gy with a 65 μm isotropic voxel size. Conversely, for a 68 mm diameter rat, a COV of 1% obtained from an image at 5.0 Gy would require an isotropic voxel size of 100 μm. These results indicate that short-term, potentially lethal, effects of ionizing radiation will limit high-resolution live animal imaging. As improvements in detector technology allow the

The zoonotic potential of Clostridium difficile from small companion animals and their owners.

Science.gov (United States)

Rabold, Denise; Espelage, Werner; Abu Sin, Muna; Eckmanns, Tim; Schneeberg, Alexander; Neubauer, Heinrich; Möbius, Nadine; Hille, Katja; Wieler, Lothar H; Seyboldt, Christian; Lübke-Becker, Antina

2018-01-01

Clostridium difficile infections (CDI) in humans range from asymptomatic carriage to life-threatening intestinal disease. Findings on C. difficile in various animal species and an overlap in ribotypes (RTs) suggest potential zoonotic transmission. However, the impact of animals for human CDI remains unclear. In a large-scale survey we collected 1,447 fecal samples to determine the occurrence of C. difficile in small companion animals (dogs and cats) and their owners and to assess potential epidemiological links within the community. The Germany-wide survey was conducted from July 2012-August 2013. PCR ribotyping, Multilocus VNTR Analysis (MLVA) and PCR detection of toxin genes were used to characterize isolated C. difficile strains. A database was defined and logistic regression used to identify putative factors associated with fecal shedding of C. difficile. In total, 1,418 samples met the inclusion criteria. The isolation rates for small companion animals and their owners within the community were similarly low with 3.0% (25/840) and 2.9% (17/578), respectively. PCR ribotyping revealed eight and twelve different RTs in animals and humans, respectively, whereas three RTs were isolated in both, humans and animals. RT 014/0, a well-known human hospital-associated lineage, was predominantly detected in animal samples. Moreover, the potentially highly pathogenic RTs 027 and 078 were isolated from dogs. Even though, C. difficile did not occur simultaneously in animals and humans sharing the same household. The results of the epidemiological analysis of factors associated with fecal shedding of C. difficile support the hypothesis of a zoonotic potential. Molecular characterization and epidemiological analysis revealed that the zoonotic risk for C. difficile associated with dogs and cats within the community is low but cannot be excluded.

Positron lifetime measurements and positron-annihilation induced auger electron spectroscpy using slow positron beams; Teisoku yodenshi bimu wo mochiita yodenshi jumyo sokutei oyobi yodenshi shometsu reiki oje denshi bunko

Energy Technology Data Exchange (ETDEWEB)

Suzuki, R. [Electrotechnical Lab., Tsukuba (Japan)

1996-02-20

Slow positron beam with less than several eV can be controlled freely such as accelerating, throttling the beam size, shortening the pulse or making pulse with short time width and so forth. These low positron beams are applied to various measurements like Doppler broadening measurement of annihilation {gamma} rays or lifetime measurement of positron, and secondary particle measurements using positron microscope, positron electron ray diffraction, flight time method and so forth. In particular, these recent years, high intensity slow positron beams were possible using accelerators like electron linac and its application is increasing. In this report, pulse shortening method for high intensity slow positron beam, and incidence energy variable positron lifetime measurement method using this slow pulsed beam and flight time type positron-annihilation-induced auger electron spectroscopy are outlined. In future, these measurements can be possible to carry out with high resolution and also with high counting rate if higher intensity monochromatic excellent positron beam than present one is produced. 31 refs., 5 figs.

Pulsars as the sources of high energy cosmic ray positrons

International Nuclear Information System (INIS)

Hooper, Dan; Blasi, Pasquale; Serpico, Pasquale Dario

2009-01-01

Recent results from the PAMELA satellite indicate the presence of a large flux of positrons (relative to electrons) in the cosmic ray spectrum between approximately 10 and 100 GeV. As annihilating dark matter particles in many models are predicted to contribute to the cosmic ray positron spectrum in this energy range, a great deal of interest has resulted from this observation. Here, we consider pulsars (rapidly spinning, magnetized neutron stars) as an alternative source of this signal. After calculating the contribution to the cosmic ray positron and electron spectra from pulsars, we find that the spectrum observed by PAMELA could plausibly originate from such sources. In particular, a significant contribution is expected from the sum of all mature pulsars throughout the Milky Way, as well as from the most nearby mature pulsars (such as Geminga and B0656+14). The signal from nearby pulsars is expected to generate a small but significant dipole anisotropy in the cosmic ray electron spectrum, potentially providing a method by which the Fermi gamma-ray space telescope would be capable of discriminating between the pulsar and dark matter origins of the observed high energy positrons

LLNL pure positron plasma program

International Nuclear Information System (INIS)

Hartley, J.H.; Beck, B.R.; Cowan, T.E.; Howell, R.H.; McDonald, J.L.; Rohatgi, R.R.; Fajans, J.; Gopalan, R.

1995-01-01

Assembly and initial testing of the Positron Time-of-Flight Trap at the Lawrence Livermore National Laboratory (LLNL) Increase Pulsed Positron Facility has been completed. The goal of the project is to accumulate at high-density positron plasma in only a few seconds., in order to facilitate study that may require destructive diagnostics. To date, densities of at least 6 x 10 6 positrons per cm 3 have been achieved

Positron annihilation spectroscopy for the determination of thickness and defect profile in thin semiconductor layers

Science.gov (United States)

Zubiaga, A.; García, J. A.; Plazaola, F.; Tuomisto, F.; Zúñiga-Pérez, J.; Muñoz-Sanjosé, V.

2007-05-01

We present a method, based on positron annihilation spectroscopy, to obtain information on the defect depth profile of layers grown over high-quality substrates. We have applied the method to the case of ZnO layers grown on sapphire, but the method can be very easily generalized to other heterostructures (homostructures) where the positron mean diffusion length is small enough. Applying the method to the ratio of W and S parameters obtained from Doppler broadening measurements, W/S plots, it is possible to determine the thickness of the layer and the defect profile in the layer, when mainly one defect trapping positron is contributing to positron trapping at the measurement temperature. Indeed, the quality of such characterization is very important for potential technological applications of the layer.

Imaging of lung metastasis tumor mouse model using [{sup 18}F]FDG small animal PET and CT

Energy Technology Data Exchange (ETDEWEB)

Kim, June Youp; Woo, Sang Keun; Lee, Tae Sup [Korea Institute of Radiological and Medical Sciences (KIRAMS), Seoul (Korea, Republic of)] (and others)

2007-02-15

The purpose of this study is to image metastaic lung melanoma model with optimal pre-conditions for animal handling by using [{sup 18}F]FDG small animal PET and clinical CT. The pre-conditions for lung region tumor imaging were 16-22 h fasting and warming temperature at 30 .deg. C. Small animal PET image was obtained at 60 min postinjection of 7.4 MBq [{sup 18}F]FDG and compared pattern of [{sup 18}F]FDG uptake and glucose standard uptake value (SUVG) of lung region between Ketamine/Xylazine (Ke/Xy) and Isoflurane (Iso) anesthetized group in normal mice. Metastasis tumor mouse model to lung was established by intravenous injection of B16-F10 cells in C57BL/6 mice. In lung metastasis tumor model, [{sup 18}F]FDG image was obtained and fused with anatomical clinical CT image. Average blood glucose concentration in normal mice were 128.0 {+-} 22.87 and 86.0 {+-} 21.65 mg/dL in Ke/Xy group and Iso group, respectively. Ke/Xy group showed 1.5 fold higher blood glucose concentration than Iso group. Lung to Background ratio (L/B) in SUVG image was 8.6 {+-} 0.48 and 12.1 {+-}0.63 in Ke/Xy group and Iso group, respectively. In tumor detection in lung region, [{sup 18}F]FDG image of Iso group was better than that of Ke/Xy group, because of high L/B ratio. Metastatic tumor location in [{sup 18}F]FDG small animal PET image was confirmed by fusion image using clinical CT. Tumor imaging in small animal lung region with [{sup 18}F]FDG small animal PET should be considered pre-conditions which fasting, warming and an anesthesia during [{sup 18}F]FDG uptake. Fused imaging with small animal PET and CT image could be useful for the detection of metastatic tumor in lung region.

Current status and future perspectives of in vivo small animal imaging using radiolabeled nanoparticles

International Nuclear Information System (INIS)

Loudos, George; Kagadis, George C.; Psimadas, Dimitris

2011-01-01

Small animal molecular imaging is a rapidly expanding efficient tool to study biological processes non-invasively. The use of radiolabeled tracers provides non-destructive, imaging information, allowing time related phenomena to be repeatedly studied in a single animal. In the last decade there has been an enormous progress in related technologies and a number of dedicated imaging systems overcome the limitations that the size of small animal possesses. On the other hand, nanoparticles (NPs) gain increased interest, due to their unique properties, which make them perfect candidates for biological applications. Over the past 5 years the two fields seem to cross more and more often; radiolabeled NPs have been assessed in numerous pre-clinical studies that range from oncology, till HIV treatment. In this article the current status in the tools, applications and trends of radiolabeled NPs reviewed.

Anti-amyloid-β-mediated positron emission tomography imaging in Alzheimer's disease mouse brains.

Directory of Open Access Journals (Sweden)

Daniel McLean

Full Text Available Antibody-mediated imaging of amyloid β (Aβ in Alzheimer's disease (AD offers a promising strategy to detect and monitor specific Aβ species, such as oligomers, that have important pathological and therapeutic relevance. The major current limitation of antibodies as a diagnostic and imaging device is poor blood-brain-barrier permeability. A classical anti-Aβ antibody, 6E10, is modified with 10 kDa polyethylene glycol (PEG and a positron emitting isotope, Copper-64 (t(½ = 12.7 h, and intravenously delivered to the TgCRND8 mouse model of Alzheimer's disease. Modification of 6E10 with PEG (6E10-PEG increases accumulation of 6E10 in brain tissue in both TgCRND8 and wild type control animals. 6E10-PEG differentiates TgCRND8 animals from wild type controls using positron emission tomography (PET and provides a framework for using antibodies to detect pathology using non-invasive medical imaging techniques.

Positron imaging feasibility studies: characteristics of [3H]thymidine uptake in rodent and canine neoplasms

International Nuclear Information System (INIS)

Larson, S.M.; Weiden, P.L.; Grunbaum, J.

1981-01-01

Uptake [ 3 H]thymidine was studied in BALB/c mice with EMT-6 sarcoma, in Buffalo rats with Morris 7777 hepatoma, and in nine dogs with spontaneous neoplasms: four lymphomas, two osteosarcomas, two soft-tissue sarcomas, and a thyroid carcinoma. High tumor-to-tissue ratios were observed for all tumor types assayed, and absolute uptakes, when computed as percent dose per gram tumor normalized for body weight, were similar for transplanted and spontaneous tumors. In the rodent tumors, radiothymidine was retained for at least 3 hr in the tumor without appreciable loss. In canine neoplasms, although the highest uptakes were observed in cellular tumors with many mitotic figures, tumor uptake showed significant variability that did not correlate with any obvious histologic change, and thus may reflect true biologic differences in metabolism among tumors at different sites in the same animal. These studies provide additional experimental evidence that the ratios of neoplastic to normal tissue and the kinetics of thymidine uptake by tumors are suitable for positron emission tomography of neoplasms in small and large, animals, including both transplanted and spontaneous tumors

Nigerian Veterinary Journal The record of J 14small animal trauma ...

African Journals Online (AJOL)

base for the establishment of protocols for trauma patient care. Trauma cases ranked first and accounted fOT46.3% of all small animal surgical cases presented during the period. Species involvement markedly favoured the canine species. Incidence of trauma was significantly higher (1)<0.05) in males (60.5%) and younger.

A computational pipeline for quantification of pulmonary infections in small animal models using serial PET-CT imaging.

Science.gov (United States)

Bagci, Ulas; Foster, Brent; Miller-Jaster, Kirsten; Luna, Brian; Dey, Bappaditya; Bishai, William R; Jonsson, Colleen B; Jain, Sanjay; Mollura, Daniel J

2013-07-23

Infectious diseases are the second leading cause of death worldwide. In order to better understand and treat them, an accurate evaluation using multi-modal imaging techniques for anatomical and functional characterizations is needed. For non-invasive imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), there have been many engineering improvements that have significantly enhanced the resolution and contrast of the images, but there are still insufficient computational algorithms available for researchers to use when accurately quantifying imaging data from anatomical structures and functional biological processes. Since the development of such tools may potentially translate basic research into the clinic, this study focuses on the development of a quantitative and qualitative image analysis platform that provides a computational radiology perspective for pulmonary infections in small animal models. Specifically, we designed (a) a fast and robust automated and semi-automated image analysis platform and a quantification tool that can facilitate accurate diagnostic measurements of pulmonary lesions as well as volumetric measurements of anatomical structures, and incorporated (b) an image registration pipeline to our proposed framework for volumetric comparison of serial scans. This is an important investigational tool for small animal infectious disease models that can help advance researchers' understanding of infectious diseases. We tested the utility of our proposed methodology by using sequentially acquired CT and PET images of rabbit, ferret, and mouse models with respiratory infections of Mycobacterium tuberculosis (TB), H1N1 flu virus, and an aerosolized respiratory pathogen (necrotic TB) for a total of 92, 44, and 24 scans for the respective studies with half of the scans from CT and the other half from PET. Institutional Administrative Panel on Laboratory Animal Care approvals were

Positron emission tomography

NARCIS (Netherlands)

Paans, AMJ

Positron Emission Tomography (PET) is a method for determining biochemical and physiological processes in vivo in a quantitative way by using radiopharmaceuticals labelled with positron emitting radionuclides as C-11, N-13, O-15 and F-18 and by measuring the annihilation radiation using a

Attitudes of Austrian veterinarians towards euthanasia in small animal practice: impacts of age and gender on views on euthanasia

OpenAIRE

Hartnack, Sonja; Springer, Svenja; Pittavino, Marta; Grimm, Herwig

2016-01-01

Background Euthanasia of pets has been described by veterinarians as ?the best and the worst? of the profession. The most commonly mentioned ethical dilemmas veterinarians face in small animal practice are: limited treatment options due to financial constraints, euthanizing of healthy animals and owners wishing to continue treatment of terminally ill animals. The aim of the study was to gain insight into the attitudes of Austrian veterinarians towards euthanasia of small animals. This include...

Positron confinement in embedded lithium nanoclusters

Science.gov (United States)

van Huis, M. A.; van Veen, A.; Schut, H.; Falub, C. V.; Eijt, S. W.; Mijnarends, P. E.; Kuriplach, J.

2002-02-01

Quantum confinement of positrons in nanoclusters offers the opportunity to obtain detailed information on the electronic structure of nanoclusters by application of positron annihilation spectroscopy techniques. In this work, positron confinement is investigated in lithium nanoclusters embedded in monocrystalline MgO. These nanoclusters were created by means of ion implantation and subsequent annealing. It was found from the results of Doppler broadening positron beam analysis that approximately 92% of the implanted positrons annihilate in lithium nanoclusters rather than in the embedding MgO, while the local fraction of lithium at the implantation depth is only 1.3 at. %. The results of two-dimensional angular correlation of annihilation radiation confirm the presence of crystalline bulk lithium. The confinement of positrons is ascribed to the difference in positron affinity between lithium and MgO. The nanocluster acts as a potential well for positrons, where the depth of the potential well is equal to the difference in the positron affinities of lithium and MgO. These affinities were calculated using the linear muffin-tin orbital atomic sphere approximation method. This yields a positronic potential step at the MgO||Li interface of 1.8 eV using the generalized gradient approximation and 2.8 eV using the insulator model.

Evaluation of a cone beam computed tomography geometry for image guided small animal irradiation

International Nuclear Information System (INIS)

Yang, Yidong; Armour, Michael; Wang, Ken Kang-Hsin; Gandhi, Nishant; Wong, John; Iordachita, Iulian; Siewerdsen, Jeffrey

2015-01-01

The conventional imaging geometry for small animal cone beam computed tomography (CBCT) is that a detector panel rotates around the head-to-tail axis of an imaged animal (‘tubular’ geometry). Another unusual but possible imaging geometry is that the detector panel rotates around the anterior-to-posterior axis of the animal (‘pancake’ geometry). The small animal radiation research platform developed at Johns Hopkins University employs the pancake geometry where a prone-positioned animal is rotated horizontally between an x-ray source and detector panel. This study is to assess the CBCT image quality in the pancake geometry and investigate potential methods for improvement. We compared CBCT images acquired in the pancake geometry with those acquired in the tubular geometry when the phantom/animal was placed upright simulating the conventional CBCT geometry. Results showed signal-to-noise and contrast-to-noise ratios in the pancake geometry were reduced in comparison to the tubular geometry at the same dose level. But the overall spatial resolution within the transverse plane of the imaged cylinder/animal was better in the pancake geometry. A modest exposure increase to two folds in the pancake geometry can improve image quality to a level close to the tubular geometry. Image quality can also be improved by inclining the animal, which reduces streak artifacts caused by bony structures. The major factor resulting in the inferior image quality in the pancake geometry is the elevated beam attenuation along the long axis of the phantom/animal and consequently increased scatter-to-primary ratio in that orientation. Not withstanding, the image quality in the pancake-geometry CBCT is adequate to support image guided animal positioning, while providing unique advantages of non-coplanar and multiple mice irradiation. This study also provides useful knowledge about the image quality in the two very different imaging geometries, i.e. pancake and tubular geometry

Evaluation of a cone beam computed tomography geometry for image guided small animal irradiation.

Science.gov (United States)

Yang, Yidong; Armour, Michael; Wang, Ken Kang-Hsin; Gandhi, Nishant; Iordachita, Iulian; Siewerdsen, Jeffrey; Wong, John

2015-07-07

The conventional imaging geometry for small animal cone beam computed tomography (CBCT) is that a detector panel rotates around the head-to-tail axis of an imaged animal ('tubular' geometry). Another unusual but possible imaging geometry is that the detector panel rotates around the anterior-to-posterior axis of the animal ('pancake' geometry). The small animal radiation research platform developed at Johns Hopkins University employs the pancake geometry where a prone-positioned animal is rotated horizontally between an x-ray source and detector panel. This study is to assess the CBCT image quality in the pancake geometry and investigate potential methods for improvement. We compared CBCT images acquired in the pancake geometry with those acquired in the tubular geometry when the phantom/animal was placed upright simulating the conventional CBCT geometry. Results showed signal-to-noise and contrast-to-noise ratios in the pancake geometry were reduced in comparison to the tubular geometry at the same dose level. But the overall spatial resolution within the transverse plane of the imaged cylinder/animal was better in the pancake geometry. A modest exposure increase to two folds in the pancake geometry can improve image quality to a level close to the tubular geometry. Image quality can also be improved by inclining the animal, which reduces streak artifacts caused by bony structures. The major factor resulting in the inferior image quality in the pancake geometry is the elevated beam attenuation along the long axis of the phantom/animal and consequently increased scatter-to-primary ratio in that orientation. Not withstanding, the image quality in the pancake-geometry CBCT is adequate to support image guided animal positioning, while providing unique advantages of non-coplanar and multiple mice irradiation. This study also provides useful knowledge about the image quality in the two very different imaging geometries, i.e. pancake and tubular geometry, respectively.

Validity of bioluminescence measurements for noninvasive in vivo imaging of tumor load in small animals

NARCIS (Netherlands)

Klerk, Clara P. W.; Overmeer, Renée M.; Niers, Tatjana M. H.; Versteeg, Henri H.; Richel, Dick J.; Buckle, Tessa; van Noorden, Cornelis J. F.; van Tellingen, Olaf

2007-01-01

A relatively new strategy to longitudinally monitor tumor load in intact animals and the effects of therapy is noninvasive bioluminescence imaging (BLI). The validity of BLI for quantitative assessment of tumor load in small animals is critically evaluated in the present review. Cancer cells are

The motivations and methodology for high-throughput PET imaging of small animals in cancer research.

NARCIS (Netherlands)

Aide, N.; Visser, E.P.; Lheureux, S.; Heutte, N.; Szanda, I.; Hicks, R.J.

2012-01-01

Over the last decade, small-animal PET imaging has become a vital platform technology in cancer research. With the development of molecularly targeted therapies and drug combinations requiring evaluation of different schedules, the number of animals to be imaged within a PET experiment has

Near Field UHF RFID Antenna System Enabling the Tracking of Small Laboratory Animals

Directory of Open Access Journals (Sweden)

Luca Catarinucci

2013-01-01

Full Text Available Radio frequency identification (RFID technology is more and more adopted in a wide range of applicative scenarios. In many cases, such as the tracking of small-size living animals for behaviour analysis purposes, the straightforward use of commercial solutions does not ensure adequate performance. Consequently, both RFID hardware and the control software should be tailored for the particular application. In this work, a novel RFID-based approach enabling an effective localization and tracking of small-sized laboratory animals is proposed. It is mainly based on a UHF Near Field RFID multiantenna system, to be placed under the animals’ cage, and able to rigorously identify the NF RFID tags implanted in laboratory animals (e.g., mice. Once the requirements of the reader antenna have been individuated, the antenna system has been designed and realized. Moreover, an algorithm based on the measured Received Signal Strength Indication (RSSI aiming at removing potential ambiguities in data captured by the multiantenna system has been developed and integrated. The animal tracking system has been largely tested on phantom mice in order to verify its ability to precisely localize each subject and to reconstruct its path. The achieved and discussed results demonstrate the effectiveness of the proposed tracking system.

Low relative error in consumer-grade GPS units make them ideal for measuring small-scale animal movement patterns

Directory of Open Access Journals (Sweden)

Greg A. Breed

2015-08-01

Full Text Available Consumer-grade GPS units are a staple of modern field ecology, but the relatively large error radii reported by manufacturers (up to 10 m ostensibly precludes their utility in measuring fine-scale movement of small animals such as insects. Here we demonstrate that for data collected at fine spatio-temporal scales, these devices can produce exceptionally accurate data on step-length and movement patterns of small animals. With an understanding of the properties of GPS error and how it arises, it is possible, using a simple field protocol, to use consumer grade GPS units to collect step-length data for the movement of small animals that introduces a median error as small as 11 cm. These small error rates were measured in controlled observations of real butterfly movement. Similar conclusions were reached using a ground-truth test track prepared with a field tape and compass and subsequently measured 20 times using the same methodology as the butterfly tracking. Median error in the ground-truth track was slightly higher than the field data, mostly between 20 and 30 cm, but even for the smallest ground-truth step (70 cm, this is still a signal-to-noise ratio of 3:1, and for steps of 3 m or more, the ratio is greater than 10:1. Such small errors relative to the movements being measured make these inexpensive units useful for measuring insect and other small animal movements on small to intermediate scales with budgets orders of magnitude lower than survey-grade units used in past studies. As an additional advantage, these units are simpler to operate, and insect or other small animal trackways can be collected more quickly than either survey-grade units or more traditional ruler/gird approaches.

Impacts of Intelligent Automated Quality Control on a Small Animal APD-Based Digital PET Scanner

Science.gov (United States)

Charest, Jonathan; Beaudoin, Jean-François; Bergeron, Mélanie; Cadorette, Jules; Arpin, Louis; Lecomte, Roger; Brunet, Charles-Antoine; Fontaine, Réjean

2016-10-01

Stable system performance is mandatory to warrant the accuracy and reliability of biological results relying on small animal positron emission tomography (PET) imaging studies. This simple requirement sets the ground for imposing routine quality control (QC) procedures to keep PET scanners at a reliable optimal performance level. However, such procedures can become burdensome to implement for scanner operators, especially taking into account the increasing number of data acquisition channels in newer generation PET scanners. In systems using pixel detectors to achieve enhanced spatial resolution and contrast-to-noise ratio (CNR), the QC workload rapidly increases to unmanageable levels due to the number of independent channels involved. An artificial intelligence based QC system, referred to as Scanner Intelligent Diagnosis for Optimal Performance (SIDOP), was proposed to help reducing the QC workload by performing automatic channel fault detection and diagnosis. SIDOP consists of four high-level modules that employ machine learning methods to perform their tasks: Parameter Extraction, Channel Fault Detection, Fault Prioritization, and Fault Diagnosis. Ultimately, SIDOP submits a prioritized faulty channel list to the operator and proposes actions to correct them. To validate that SIDOP can perform QC procedures adequately, it was deployed on a LabPET™ scanner and multiple performance metrics were extracted. After multiple corrections on sub-optimal scanner settings, a 8.5% (with a 95% confidence interval (CI) of [7.6, 9.3]) improvement in the CNR, a 17.0% (CI: [15.3, 18.7]) decrease of the uniformity percentage standard deviation, and a 6.8% gain in global sensitivity were observed. These results confirm that SIDOP can indeed be of assistance in performing QC procedures and restore performance to optimal figures.

Simulation of the annihilation emission of galactic positrons; Modelisation de l'emission d'annihilation des positrons Galactiques

Energy Technology Data Exchange (ETDEWEB)

Gillard, W

2008-01-15

Positrons annihilate in the central region of our Galaxy. This has been known since the detection of a strong emission line centered on an energy of 511 keV in the direction of the Galactic center. This gamma-ray line is emitted during the annihilation of positrons with electrons from the interstellar medium. The spectrometer SPI, onboard the INTEGRAL observatory, performed spatial and spectral analyses of the positron annihilation emission. This thesis presents a study of the Galactic positron annihilation emission based on models of the different interactions undergone by positrons in the interstellar medium. The models are relied on our present knowledge of the properties of the interstellar medium in the Galactic bulge, where most of the positrons annihilate, and of the physics of positrons (production, propagation and annihilation processes). In order to obtain constraints on the positrons sources and physical characteristics of the annihilation medium, we compared the results of the models to measurements provided by the SPI spectrometer. (author)

Mining the bulk positron lifetime

International Nuclear Information System (INIS)

Aourag, H.; Guittom, A.

2009-01-01

We introduce a new approach to investigate the bulk positron lifetimes of new systems based on data-mining techniques. Through data mining of bulk positron lifetimes, we demonstrate the ability to predict the positron lifetimes of new semiconductors on the basis of available semiconductor data already studied. Informatics techniques have been applied to bulk positron lifetimes for different tetrahedrally bounded semiconductors in order to discover computational design rules. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Solvated Positron Chemistry. Competitive Positron Reactions with Halide Ions in Water

DEFF Research Database (Denmark)

Christensen, Palle; Pedersen, Niels Jørgen; Andersen, J. R.

1979-01-01

It is shown by means of the angular correlation technique that the binding of positrons to halides is strongly influenced by solvation effects. For aqueous solutions we find increasing values for the binding energies between the halide and the positron with increasing mass of the halide...

Dynamic {sup 11}C-methionine PET analysis has an additional value for differentiating malignant tumors from granulomas: an experimental study using small animal PET

Energy Technology Data Exchange (ETDEWEB)

Zhao, Songji; Zhao, Yan [Hokkaido University, Department of Nuclear Medicine, Graduate School of Medicine, Sapporo (Japan); Hokkaido University, Department of Tracer Kinetics and Bioanalysis, Graduate School of Medicine, Sapporo (Japan); Kuge, Yuji; Hatano, Toshiyuki [Hokkaido University, Central Institute of Isotope Science, Sapporo (Japan); Yi, Min; Kohanawa, Masashi [Hokkaido University, Department of Advanced Medicine, Graduate School of Medicine, Sapporo (Japan); Magota, Keiichi; Tamaki, Nagara [Hokkaido University, Department of Nuclear Medicine, Graduate School of Medicine, Sapporo (Japan); Nishijima, Ken-ichi [Hokkaido University, Department of Molecular Imaging, Graduate School of Medicine, Sapporo (Japan)

2011-10-15

We evaluated whether the dynamic profile of L-{sup 11}C-methionine ({sup 11}C-MET) may have an additional value in differentiating malignant tumors from granulomas in experimental rat models by small animal positron emission tomography (PET). Rhodococcus aurantiacus and allogenic rat C6 glioma cells were inoculated, respectively, into the right and left calf muscles to generate a rat model bearing both granulomas and tumors (n = 6). Ten days after the inoculations, dynamic {sup 11}C-MET PET was performed by small animal PET up to 120 min after injection of {sup 11}C-MET. The next day, after overnight fasting, the rats were injected with {sup 18}F-2-deoxy-2-fluoro-D-glucose ({sup 18}F-FDG), and dynamic {sup 18}F-FDG PET was performed up to 180 min. The time-activity curves, static images, and mean standardized uptake value (SUV) in the lesions were calculated. {sup 11}C-MET uptake in the granuloma showed a slow exponential clearance after an initial distribution, while the uptake in the tumor gradually increased with time. The dynamic pattern of {sup 11}C-MET uptake in the granuloma was significantly different from that in the tumor (p < 0.001). In the static analysis of {sup 11}C-MET, visual assessment and SUV analysis could not differentiate the tumor from the granuloma in all cases, although the mean SUV in the granuloma (1.48 {+-} 0.09) was significantly lower than that in the tumor (1.72 {+-} 0.18, p < 0.01). The dynamic patterns, static images, and mean SUVs of {sup 18}F-FDG in the granuloma were similar to those in the tumor (p = NS). Dynamic {sup 11}C-MET PET has an additional value for differentiating malignant tumors from granulomatous lesions, which deserves further elucidation in clinical settings. (orig.)

Ethical dilemmas encountered by small animal veterinarians: characterisation, responses, consequences and beliefs regarding euthanasia.

Science.gov (United States)

Kipperman, Barry; Morris, Patricia; Rollin, Bernard

2018-05-12

Small animal veterinarians' opinions were investigated regarding the frequency and nature of ethical dilemmas encountered, beliefs regarding euthanasia and balancing client and animal interests, prevalence and value of ethics training and proposals to mitigate the stressful effects of ethical dilemmas. The majority (52 per cent) of 484 respondents in the USA indicated via an online survey experiencing an ethical dilemma regarding the interests of clients and those of their patients at least weekly. Scenarios involving client financial concerns were commonly reported causes of ethical conflicts. While only 20 per cent of respondents indicated that other practitioners prioritise patient interests, 50 per cent of respondents characterised their own behaviour as prioritising patients. Most respondents (52 per cent) reported that ethical dilemmas are the leading cause, or are one of many equal causes, of work-related stress. Less experienced practitioners, general practitioners and associate veterinarians were more likely to encounter situations they defined as ethical dilemmas, and female respondents were more likely to find ethical dilemmas stressful. Most small animal veterinarians experience ethical dilemmas regularly, which contribute to moral stress. Results suggested that most small animal practitioners believe that greater awareness of moral stress and providing training in ethical theories and tools for coping with ethical dilemmas can ameliorate moral stress. © British Veterinary Association (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Characterizing microstructural changes in ferritic steels by positron annihilation spectroscopy: Studies on modified 9Cr-1Mo steel

Energy Technology Data Exchange (ETDEWEB)

Hari Babu, S., E-mail: shb@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India); Rajkumar, K.V. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India); Hussain, S. [UGC-DAE CSR, Kokilamedu 603 104, TN (India); Amarendra, G.; Sundar, C.S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India); Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Positron lifetime technique probing microstructure of ferritic/martensitic steels. Black-Right-Pointing-Pointer Correlation between positron lifetime, ultrasonic and hardness. Black-Right-Pointing-Pointer Complementary nature of positron annihilation spectroscopy in probing defects. Black-Right-Pointing-Pointer Distinguishing precipitation stages by positron annihilation spectroscopy. - Abstract: Applicability of positron annihilation spectroscopy in probing the microstructural changes in ferritic steels has been investigated with thermal treatment studies on modified 9Cr-1Mo steel, during 300-1273 K. Positron lifetime results are compared with those of ultrasonic velocity and hardness techniques with two initial microstructural conditions i.e., normalized and tempered condition as well as only normalized condition. In first case, positron lifetime is found to be sensitive to small changes in metal carbide precipitation which could not be probed by other two techniques. In later case, positron lifetime is found to be sensitive to defect annealing until 673 K and in distinguishing the growth and coarsening of metal carbide precipitation stages during 773-1073 K. The present study suggests that by combining positron lifetime, ultrasonic velocity and hardness measurements, it is possible to distinguish distinct microstructures occurring at different stages.

Development of a transmission positron microscope

Energy Technology Data Exchange (ETDEWEB)

Matsuya, M., E-mail: matsuya@jeol.co.jp [JEOL Ltd., 1-2 Musashino, 3-Chome, Akishima, Tokyo 196-8558 (Japan); Jinno, S. [Department of Applied Chemistry, Chiba University, Yayoi, Inage, Chiba, Chiba 263-8552 (Japan); Ootsuka, T.; Inoue, M. [JEOL Ltd., 1-2 Musashino, 3-Chome, Akishima, Tokyo 196-8558 (Japan); Kurihara, T. [High Energy Accelerator Research Organization, Oho, Tsukuba, Ibaraki 305-0801 (Japan); Doyama, M.; Inoue, M. [Teikyo University of Science and Technology, Uenohara, Yamanashi 409-0913 (Japan); Fujinami, M. [Department of Applied Chemistry, Chiba University, Yayoi, Inage, Chiba, Chiba 263-8552 (Japan)

2011-07-21

A practical transmission positron microscope (TPM) JEM-1011B has been developed to survey differences in the interaction of positron and electron beams with materials, and is installed in the Slow Positron Facility of High Energy Accelerator Research Organization (KEK). The TPM can share positron and electron beams, and can also be used as a transmission electron microscope (TEM). Positron transmission images up to magnification 10,000x (resolution: 50 nm) and positron diffraction patterns up to 044 family were successfully obtained by the TPM comparing them with those of electrons. The differences in material transmittances for both beams have been measured, and can be explained by the calculated results of the Monte Carlo simulation code PENELOPE-2008.

SU-E-T-457: Design and Characterization of An Economical 192Ir Hemi-Brain Small Animal Irradiator

International Nuclear Information System (INIS)

Grams, M; Wilson, Z; Sio, T; Beltran, C; Tryggestad, E; Gupta, S; Blackwell, C; McCollough, K; Sarkaria, J; Furutani, K

2014-01-01

Purpose: To describe the design and dosimetric characterization of a simple and economical small animal irradiator. Methods: A high dose rate 192Ir brachytherapy source from a commercially available afterloader was used with a 1.3 centimeter thick tungsten collimator to provide sharp beam penumbra suitable for hemi-brain irradiation of mice. The unit is equipped with continuous gas anesthesia to allow robust animal immobilization. Dosimetric characterization of the device was performed with Gafchromic film. The penumbra from the small animal irradiator was compared under similar collimating conditions to the penumbra from 6 MV photons, 6 MeV electrons, and 20 MeV electrons from a linear accelerator as well as 300 kVp photons from an orthovoltage unit and Monte Carlo simulated 90 MeV protons. Results: The tungsten collimator provides a sharp penumbra suitable for hemi-brain irradiation, and dose rates on the order of 200 cGy/minute were achieved. The sharpness of the penumbra attainable with this device compares favorably to those measured experimentally for 6 MV photons, and 6 and 20 MeV electron beams from a linear accelerator. Additionally, the penumbra was comparable to those measured for a 300 kVp orthovoltage beam and a Monte Carlo simulated 90 MeV proton beam. Conclusions: The small animal irradiator described here can be built for under $1,000 and used in conjunction with any commercial brachytherapy afterloader to provide a convenient and cost-effective option for small animal irradiation experiments. The unit offers high dose rate delivery and sharp penumbra, which is ideal for hemi-brain irradiation of mice. With slight modifications to the design, irradiation of sites other than the brain could be accomplished easily. Due to its simplicity and low cost, the apparatus described is an attractive alternative for small animal irradiation experiments requiring a sharp penumbra

Positron annihilation microprobe

Energy Technology Data Exchange (ETDEWEB)

Canter, K F [Brandeis Univ., Waltham, MA (United States)

1997-03-01

Advances in positron annihilation microprobe development are reviewed. The present resolution achievable is 3 {mu}m. The ultimate resolution is expected to be 0.1 {mu}m which will enable the positron microprobe to be a valuable tool in the development of 0.1 {mu}m scale electronic devices in the future. (author)

Positron lifetimes in deformed copper

International Nuclear Information System (INIS)

Hinode, Kenji; Tanigawa, Shoichiro; Doyama, Masao

1976-01-01

Positron lifetime measurements were performed for Cu samples with different densities of lattice defects. The lifetime spectra were successfully resolved into two components with the help of the well established analysis program. Obtained results were quite consistent with those expected from the trapping model. The positron trapping mechanism from free to trapped states and the initial condition of the model were especially checked. Deduced values obtained for tau sub(c) (lifetime of free positrons) and tau sub(t) (lifetime of trapped positrons) were 122+-5 psec and 176+-5 psec, respectively. (auth.)

The value of positron emission tomography in patients with non-small cell lung cancer

Energy Technology Data Exchange (ETDEWEB)

Kee, Frank [Centre for Public Health, Queen' s University Belfast, Mulhouse Building, Royal Victoria Hospital Site, Grosvenor Road, Belfast BT12 6BJ, Northern Ireland (United Kingdom)], E-mail: f.kee@qub.ac.uk; Erridge, Sara [Edinburgh Cancer Centre, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XU, Scotland (United Kingdom); Bradbury, Ian [Frontier Science (Scotland) Ltd., Grampian View, Kincraig, Inverness-shire PH21 1NA, Scotland (United Kingdom); Cairns, Karen [School of Maths and Physics, Queen' s University Belfast, David Bates Building, University Road, Belfast BT7 1NN, Northern Ireland (United Kingdom)

2010-01-15

Background: Pre-operative assessment of non-small cell lung cancer (NSCLC) is a major application of positron emission tomography (FDG-PET). Despite substantial evidence of diagnostic accuracy, relatively little attention has been paid to its effects on patient outcomes. This paper addresses this by extending an existing decision model to include patient-elicited utilities. Patients and methods: A decision-tree model of the effect of FDG-PET on pre-operative staging was converted to a Markov model. Utilities for futile and appropriate thoracotomy were elicited from 75 patients undergoing staging investigation for NSCLC. The decision model was then used to estimate the expected value of perfect information (EVPI) associated with three sources of uncertainty-the accuracy of PET, the accuracy of CT and the patient related utility of a futile thoracotomy. Results: The model confirmed the apparent cost-effectiveness of FDG-PET and indicated that the EVPI associated with the utility of futile thoracotomy considerably exceeds that associated with measures of accuracy. Conclusion: The study highlights the importance of patient related utilities in assessing the cost-effectiveness of diagnostic technologies. In the specific case of PET for pre-operative staging of NSCLC, future research effort should focus on such elicitation, rather than further refinement of accuracy estimates.

The value of positron emission tomography in patients with non-small cell lung cancer

International Nuclear Information System (INIS)

Kee, Frank; Erridge, Sara; Bradbury, Ian; Cairns, Karen

2010-01-01

Background: Pre-operative assessment of non-small cell lung cancer (NSCLC) is a major application of positron emission tomography (FDG-PET). Despite substantial evidence of diagnostic accuracy, relatively little attention has been paid to its effects on patient outcomes. This paper addresses this by extending an existing decision model to include patient-elicited utilities. Patients and methods: A decision-tree model of the effect of FDG-PET on pre-operative staging was converted to a Markov model. Utilities for futile and appropriate thoracotomy were elicited from 75 patients undergoing staging investigation for NSCLC. The decision model was then used to estimate the expected value of perfect information (EVPI) associated with three sources of uncertainty-the accuracy of PET, the accuracy of CT and the patient related utility of a futile thoracotomy. Results: The model confirmed the apparent cost-effectiveness of FDG-PET and indicated that the EVPI associated with the utility of futile thoracotomy considerably exceeds that associated with measures of accuracy. Conclusion: The study highlights the importance of patient related utilities in assessing the cost-effectiveness of diagnostic technologies. In the specific case of PET for pre-operative staging of NSCLC, future research effort should focus on such elicitation, rather than further refinement of accuracy estimates.

The value of positron emission tomography in patients with non-small cell lung cancer.

Science.gov (United States)

Kee, Frank; Erridge, Sara; Bradbury, Ian; Cairns, Karen

2010-01-01

Pre-operative assessment of non-small cell lung cancer (NSCLC) is a major application of positron emission tomography (FDG-PET). Despite substantial evidence of diagnostic accuracy, relatively little attention has been paid to its effects on patient outcomes. This paper addresses this by extending an existing decision model to include patient-elicited utilities. A decision-tree model of the effect of FDG-PET on pre-operative staging was converted to a Markov model. Utilities for futile and appropriate thoracotomy were elicited from 75 patients undergoing staging investigation for NSCLC. The decision model was then used to estimate the expected value of perfect information (EVPI) associated with three sources of uncertainty-the accuracy of PET, the accuracy of CT and the patient related utility of a futile thoracotomy. The model confirmed the apparent cost-effectiveness of FDG-PET and indicated that the EVPI associated with the utility of futile thoracotomy considerably exceeds that associated with measures of accuracy. The study highlights the importance of patient related utilities in assessing the cost-effectiveness of diagnostic technologies. In the specific case of PET for pre-operative staging of NSCLC, future research effort should focus on such elicitation, rather than further refinement of accuracy estimates. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

Collimator optimization for small animal radiation therapy at a micro-CT

Energy Technology Data Exchange (ETDEWEB)

Felix, Manuela C. [Heidelberg Univ., Mannheim (Germany). Medical Radiation Physics/Radiation Protection; Heidelberg Univ., Mannheim (Germany). Dept. of Radiation Oncology; Glatting, Gerhard [Heidelberg Univ., Mannheim (Germany). Medical Radiation Physics/Radiation Protection; Giordano, Frank A.; Wenz, Frederik; Fleckenstein, Jens [Heidelberg Univ., Mannheim (Germany). Dept. of Radiation Oncology; Brockmann, Marc A. [Heidelberg Univ., Mannheim (Germany). Dept. of Neuroradiology; University Medical Center Mainz (Germany). Dept. of Neuroradiology

2017-05-01

In radiation therapy of small animals treatment depths range from a few millimetres to several centimetres. In order to spare surrounding organs at risk steep dose gradients are necessary. To minimize the treatment time, and therefore the strain to the animals, a high dose rate is required. A description how these parameters can be optimized through an appropriate choice of collimators with different source surface distances (SSD) as well as different materials and geometries is presented. An industrial micro-CT unit (Y.Fox, YXLON GmbH, Hamburg, Germany) was converted into a precision irradiator for small animals. Different collimators of either stainless steel (Fe) with cylindrical bores (SSD = 42 mm) or tungsten (W) with conical bores (SSD = 14 mm) were evaluated. The dosimetry of very small radiation fields presents a challenge and was performed with GafChromic EBT3 films (Ashland, Vayne, KY, USA) in a water phantom. The films were calibrated with an ionization chamber in the uncollimated field. Treatments were performed via a rotation of the objects with a fixed radiation source. As expected, the shorter SSD of the W-collimators resulted in a (4.5 ± 1.6)-fold increase of the dose rates compared to the corresponding Fe-collimators. The ratios of the dose rates at 1 mm and 10 mm depth in the water phantom was (2.6 ± 0.2) for the Fe- and (4.5 ± 0.1) for the W-collimators. For rotational treatments in a cylindrical plastic phantom maximum dose rates of up to 1.2 Gy/min for Fe- and 5.1 Gy/min for W-collimators were measured. Choosing the smallest possible SSD leads to a high dose rate and a high surface dose, which is of advantage for the treatment of superficial target volumes. For larger SSD the dose rate is lower and the depth dose curve is shallower. This leads to a reduction of the surface dose and is best suited for treatments of deeper seated target volumes. Divergent collimator bores have, due to the reduced scatter within the collimators, a steeper

Positron annihilation near fractal surfaces

International Nuclear Information System (INIS)

Lung, C.W.; Deng, K.M.; Xiong, L.Y.

1991-07-01

A model for positron annihilation in the sub-surface region near a fractal surface is proposed. It is found that the power law relationship between the mean positron implantation depth and incident positron energy can be used to measure the fractal dimension of the fractal surface in materials. (author). 10 refs, 2 figs

High energy positron imaging

International Nuclear Information System (INIS)

Chen Shengzu

2003-01-01

The technique of High Energy Positron Imaging (HEPI) is the new development and extension of Positron Emission Tomography (PET). It consists of High Energy Collimation Imaging (HECI), Dual Head Coincidence Detection Imaging (DHCDI) and Positron Emission Tomography (PET). We describe the history of the development and the basic principle of the imaging methods of HEPI in details in this paper. Finally, the new technique of the imaging fusion, which combined the anatomical image and the functional image together are also introduced briefly

Detectors, sampling, shielding, and electronics for positron emission tomography

International Nuclear Information System (INIS)

Derenzo, S.E.

1981-08-01

A brief discussion of the important design elements for positron emission tomographs is presented. The conclusions are that the instrumentation can be improved by the use of larger numbers of small, efficient detectors closely packed in many rings, the development of new detector materials, and novel electronic designs to reduce the deadtime and increase maximum event rates

Biological X-ray irradiator characterization for use with small animals and cells.

Science.gov (United States)

Bruno, A Colello; Mazaro, S J; Amaral, L L; Rego, E M; Oliveira, H F; Pavoni, J F

2017-03-02

This study presents the characterization of an X-ray irradiator through dosimetric tests, which confirms the actual dose rate that small animals and cells will be exposed to during radiobiological experiments. We evaluated the linearity, consistency, repeatability, and dose distribution in the positions in which the animals or cells are placed during irradiation. In addition, we evaluated the performance of the X-ray tube (voltage and tube operating current), the radiometric survey (leakage radiation) and safety devices. The irradiator default setting was established as 160 kV and 25 mA. Tests showed that the dose rate was linear overtime (R2=1) and remained stable for long (constant) and short (repeatability) intervals between readings. The mean dose rate inside the animal cages was 1.27±0.06 Gy/min with a uniform beam of 95.40% (above the minimum threshold guaranteed by the manufacturer). The mean dose rate inside the cell plates was 0.92±0.19 Gy/min. The dose rate dependence with tube voltage and current presented a quadratic and linear relationship, respectively. There was no observed mechanical failure during evaluation of the irradiator safety devices and the radiometric survey obtained a maximum ambient equivalent dose rate of 0.26 mSv/h, which exempts it from the radiological protection requirements of the International Atomic Energy Agency. The irradiator characterization enables us to perform radiobiological experiments, and assists or even replaces traditional therapy equipment (e.g., linear accelerators) for cells and small animal irradiation, especially in early research stages.

Biological X-ray irradiator characterization for use with small animals and cells

Directory of Open Access Journals (Sweden)

A. Colello Bruno

Full Text Available This study presents the characterization of an X-ray irradiator through dosimetric tests, which confirms the actual dose rate that small animals and cells will be exposed to during radiobiological experiments. We evaluated the linearity, consistency, repeatability, and dose distribution in the positions in which the animals or cells are placed during irradiation. In addition, we evaluated the performance of the X-ray tube (voltage and tube operating current, the radiometric survey (leakage radiation and safety devices. The irradiator default setting was established as 160 kV and 25 mA. Tests showed that the dose rate was linear overtime (R2=1 and remained stable for long (constant and short (repeatability intervals between readings. The mean dose rate inside the animal cages was 1.27±0.06 Gy/min with a uniform beam of 95.40% (above the minimum threshold guaranteed by the manufacturer. The mean dose rate inside the cell plates was 0.92±0.19 Gy/min. The dose rate dependence with tube voltage and current presented a quadratic and linear relationship, respectively. There was no observed mechanical failure during evaluation of the irradiator safety devices and the radiometric survey obtained a maximum ambient equivalent dose rate of 0.26 mSv/h, which exempts it from the radiological protection requirements of the International Atomic Energy Agency. The irradiator characterization enables us to perform radiobiological experiments, and assists or even replaces traditional therapy equipment (e.g., linear accelerators for cells and small animal irradiation, especially in early research stages.

High intensity positron program at LLNL

International Nuclear Information System (INIS)

Asoka-Kumar, P.; Howell, R.; Stoeffl, W.; Carter, D.

1999-01-01

Lawrence Livermore National Laboratory (LLNL) is the home of the world's highest current beam of keV positrons. The potential for establishing a national center for materials analysis using positron annihilation techniques around this capability is being actively pursued. The high LLNL beam current will enable investigations in several new areas. We are developing a positron microprobe that will produce a pulsed, focused positron beam for 3-dimensional scans of defect size and concentration with submicron resolution. Below we summarize the important design features of this microprobe. Several experimental end stations will be available that can utilize the high current beam with a time distribution determined by the electron linac pulse structure, quasi-continuous, or bunched at 20 MHz, and can operate in an electrostatic or (and) magnetostatic environment. Some of the planned early experiments are: two-dimensional angular correlation of annihilation radiation of thin films and buried interfaces, positron diffraction holography, positron induced desorption, and positron induced Auger spectroscopy

High intensity positron program at LLNL

International Nuclear Information System (INIS)

Asoka-Kumar, P.; Howell, R.H.; Stoeffl, W.

1998-01-01

Lawrence Livermore National Laboratory (LLNL) is the home of the world's highest current beam of keV positrons. The potential for establishing a national center for materials analysis using positron annihilation techniques around this capability is being actively pursued. The high LLNL beam current will enable investigations in several new areas. We are developing a positron microprobe that will produce a pulsed, focused positron beam for 3-dimensional scans of defect size and concentration with submicron resolution. Below we summarize the important design features of this microprobe. Several experimental end stations will be available that can utilize the high current beam with a time distribution determined by the electron linac pulse structure, quasi-continuous, or bunched at 20 MHz, and can operate in an electrostatic or (and) magnetostatic environment. Some of the planned early experiments are: two-dimensional angular correlation of annihilation radiation of thin films and buried interfaces, positron diffraction holography, positron induced desorption, and positron induced Auger spectra

Positron and positronium annihilation in silica-based thin films studied by a pulsed positron beam

International Nuclear Information System (INIS)

Suzuki, R.; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Shioya, Y.; Ishimaru, T.

2003-01-01

Positron and positronium annihilation in silica-based thin films has been investigated by means of measurement techniques with a monoenergetic pulsed positron beam. The age-momentum correlation study revealed that positron annihilation in thermally grown SiO 2 is basically the same as that in bulk amorphous SiO 2 while o-Ps in the PECVD grown SiCOH film predominantly annihilate with electrons of C and H at the microvoid surfaces. We also discuss time-dependent three-gamma annihilation in porous low-k films by two-dimensional positron annihilation lifetime spectroscopy

Positron astronomy with SPI/INTEGRAL

International Nuclear Information System (INIS)

Weidenspointner, G.; Diehl, R.; Strong, A.; Weidenspointner, G.; Skinner, G.K.; Skinner, G.K.; Jean, P.; Knoedlseder, J.; Von Ballmoos, P.; Cordier, B.; Schanne, S.; Winkler, C.

2008-01-01

We provide an overview of positron astronomy results that have been obtained using the INTEGRAL spectrometer SPI, and discuss their implications for the still mysterious origin of positrons in our Galaxy. It has long been known that the 511 keV positron annihilation emission is strongest from the central region of our Galaxy. Recently, it has been discovered with the SPI spectrometer that the weaker 511 keV line emission from the inner Galactic disk appears to be asymmetric, with the emission to the west of the Galactic center being about twice as strong than that to the east. This distribution of positron annihilation resembles that of low mass X-ray binaries as observed with the INTEGRAL imager IBIS at hard X-ray energies, suggesting that these systems could provide a significant portion of the positrons in our Galaxy. In addition, the spectrometer SPI has permitted unprecedented spectroscopy of annihilation radiation from the bulge and disk regions of the Galaxy, which commences to yield important insights into the conditions of the medium in which the positrons annihilate. (authors)

Dynamic studies of small animals with a four-color diffuse optical tomography imager

International Nuclear Information System (INIS)

Schmitz, Christoph H.; Graber, Harry L.; Pei Yaling; Farber, Mark; Stewart, Mark; Levina, Rita D.; Levin, Mikhail B.; Xu Yong; Barbour, Randall L.

2005-01-01

We present newly developed instrumentation for full-tomographic four-wavelength, continuous wave, diffuse optical tomography (DOT) imaging on small animals. A small-animal imaging stage was constructed, from materials compatible with in-magnet studies, which offers stereotaxic fixation of the animal and precise, stable probe positioning. Instrument performance, based on calibration and phantom studies, demonstrates excellent long-term signal stability. DOT measurements of the functional rat brain response to electric paw stimulation are presented, and these demonstrate high data quality and excellent sensitivity to hemodynamic changes. A general linear model analysis on individual trials is used to localize and quantify the occurrence of functional behavior associated with the different hemoglobin state responses. Statistical evaluation of outcomes of individual trials is employed to identify significant regional response variations for different stimulation sites. Image results reveal a diffuse cortical response and a strong reaction of the thalamus, both indicative of activation of pain pathways by the stimulation. In addition, a weaker lateralized functional component is observed in the brain response, suggesting presence of motor activation. An important outcome of the experiment is that it shows that reactions to individual provocations can be monitored, without having to resort to signal averaging. Thus the described technology may be useful for studies of long-term trends in hemodynamic response, as would occur, for example, in behavioral studies involving freely moving animals

A 3D HIDAC-PET camera with sub-millimeter resolution for imaging small animals

International Nuclear Information System (INIS)

Jeavons, A.P.; Chandler, R.A.; Dettmar, C.A.R.

1999-01-01

A HIDAC-PET camera consisting essentially of 5 million 0.5 mm gas avalanching detectors has been constructed for small-animal imaging. The particular HIDAC advantage--a high 3D spatial resolution--has been improved to 0.95 mm fwhm and to 0.7 mm fwhm when reconstructing with 3D-OSEM methods incorporating resolution recovery. A depth-of-interaction resolution of 2.5 mm is implicit, due to the laminar construction. Scatter-corrected sensitivity, at 8.9 cps/kBq (i.e. 0.9%) from a central point source, or 7.2 cps/kBq (543 cps/kBq/cm 3 ) from a distributed (40 mm diameter, 60 mm long) source is now much higher than previous, and other, work. A field-of-view of 100 mm (adjustable to 200 mm) diameter by 210 mm axially permits whole-body imaging of small animals, containing typically 4MBqs of activity, at 40 kcps of which 16% are random coincidences, with a typical scatter fraction of 44%. Throughout the field-of-view there are no positional distortions and relative quantitation is uniform to ± 3.5%, but some variation of spatial resolution is found. The performance demonstrates that HIDAC technology is quite appropriate for small-animal PET cameras

Scalable electrophysiology in intact small animals with nanoscale suspended electrode arrays

Science.gov (United States)

Gonzales, Daniel L.; Badhiwala, Krishna N.; Vercosa, Daniel G.; Avants, Benjamin W.; Liu, Zheng; Zhong, Weiwei; Robinson, Jacob T.

2017-07-01

Electrical measurements from large populations of animals would help reveal fundamental properties of the nervous system and neurological diseases. Small invertebrates are ideal for these large-scale studies; however, patch-clamp electrophysiology in microscopic animals typically requires invasive dissections and is low-throughput. To overcome these limitations, we present nano-SPEARs: suspended electrodes integrated into a scalable microfluidic device. Using this technology, we have made the first extracellular recordings of body-wall muscle electrophysiology inside an intact roundworm, Caenorhabditis elegans. We can also use nano-SPEARs to record from multiple animals in parallel and even from other species, such as Hydra littoralis. Furthermore, we use nano-SPEARs to establish the first electrophysiological phenotypes for C. elegans models for amyotrophic lateral sclerosis and Parkinson's disease, and show a partial rescue of the Parkinson's phenotype through drug treatment. These results demonstrate that nano-SPEARs provide the core technology for microchips that enable scalable, in vivo studies of neurobiology and neurological diseases.

9.4 T small animal MRI using clinical components for direct translational studies.

Science.gov (United States)

Felder, Jörg; Celik, A Avdo; Choi, Chang-Hoon; Schwan, Stefan; Shah, N Jon

2017-12-28

Magnetic resonance is a major preclinical and clinical imaging modality ideally suited for longitudinal studies, e.g. in pharmacological developments. The lack of a proven platform that maintains an identical imaging protocol between preclinical and clinical platforms is solved with the construction of an animal scanner based on clinical hard- and software. A small animal magnet and gradient system were connected to a clinical MR system. Several hardware components were either modified or built in-house to achieve compatibility. The clinical software was modified to account for the different field-of-view of a preclinical MR system. The established scanner was evaluated using clinical QA protocols, and platform compatibility for translational research was verified against clinical scanners of different field strength. The constructed animal scanner operates with the majority of clinical imaging sequences. Translational research is greatly facilitated as protocols can be shared between preclinical and clinical platforms. Hence, when maintaining sequences parameters, maximum similarity between pulses played out on a human or an animal system is maintained. Coupling of a small animal magnet with a clinical MR system is a flexible, easy to use way to establish and advance translational imaging capability. It provides cost and labor efficient translational capability as no tedious sequence reprogramming between moieties is required and cross-platform compatibility of sequences facilitates multi-center studies.

In vivo fluorescence enhanced optical tomography reconstruction of lung cancer of non immersed small animals

Science.gov (United States)

Hervé, L.; Koenig, A.; Da Silva, A.; Berger, M.; Boutet, J.; Dinten, J. M.; Peltié, P.; Rizo, P.

2007-02-01

Fluorescence enhanced diffuse optical tomography (fDOT) is envisioned to be useful to collect functional information from small animal models. For oncology applications, cancer-targeted fluorescent markers can be used as a surrogate of the cancer activity. We are developing a continuous wave fDOT bench intended to be integrated in systems dedicated to whole body small animal fluorescence analyses. The focus is currently put on the reconstruction of non immersed small animals imaged by a CCD camera. The reconstruction stage already corrects the tissue heterogeneity artifacts through the computation of an optical heterogeneity map. We will show how this formalism coupled with the determination of the animal boundaries performed by a laser scanner, can be used to manage non contact acquisitions. The time of reconstruction for a 10 × 9 laser source positions, 45 × 40 detector elements and 14 × 11 × 14 mesh voxels is typically 10 minutes on a 3GHz PCs corresponding to the acquisition time allowing the two tasks to be performed in parallel. The system is validated on an in vivo experiment performed on three healthy nude mice and a mouse bearing a lung tumor at 10, 12 and 14 days after implantation allowing the follow up of the disease. The 3D fluorescence reconstructions of this mouse are presented and the total fluorescence amounts are compared.

The Positron-Electron Correlation Energy In ZnO Calculated With The Modified Single Wave Function Of Positron

International Nuclear Information System (INIS)

Chau Van Tao; Trinh Hoa Lang; Le Hoang Chien; Nguyen Huu Loc; Nguyen Anh Tuan

2011-01-01

Positron-electron correlation energy of the ZnO - positron system is studied on assumption that positron binds with the outer shell electrons of Zinc and Oxygen to form the pseudo ZnO - positron molecule before it annihilates with one of these electrons. In this work, the single wave function for positron is form by LCAO approximation and is modified according to the principle of linear superposition, and by using Variational Quantum Monte Carlo method (VQMC) [7] the correlation energy of this system is estimated with the value E c e-p = - 9.3 ± 1.1 eV. In the theoretical aspect it turns out that this result is more reasonable and closer to those of other methods [3] than the one which is done without modifying the wave function of positron [1]. To confirm this legitimate approach, however, the further calculations of positron annihilation rate in ZnO have to be carried out in our next work. (author)

A Southern African positron beam

International Nuclear Information System (INIS)

Britton, D.T.; Haerting, M.; Teemane, M.R.B.; Mills, S.; Nortier, F.M.; Van der Walt, T.N.

1997-01-01

The first stage of a state of the art positron beam, being constructed at the University of Cape Town, is currently being brought into operation. This is the first positron beam on the African continent, as well as being the first positron beam dedicated to solid and surface studies in the southern hemisphere. The project also contains a high proportion of local development, including the encapsulated 22 Na positron source developed by our collaboration. Novel features in the design include a purely magnetic in-line deflector, working in the solenoidal guiding field, to eliminate unmoderated positrons and block the direct line of sight to the source. A combined magnetic projector and single pole probe forming lens is being implemented in the second phase of construction to achieve a spot size of 10 μm without remoderation

First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation

Energy Technology Data Exchange (ETDEWEB)

Larsson, Daniel H.; Lundstroem, Ulf; Burvall, Anna; Hertz, Hans M. [Department of Applied Physics, KTH Royal Institute of Technology/Albanova, 10691 Stockholm (Sweden); Westermark, Ulrica K.; Arsenian Henriksson, Marie [Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, 17177 Stockholm (Sweden)

2013-02-15

Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with {approx}7 {mu}m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 {mu}m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

Positron Transport and Annihilation in the Galactic Bulge

Directory of Open Access Journals (Sweden)

Fiona Helen Panther

2018-03-01

Full Text Available The annihilation of positrons in the Milky Way Galaxy has been observed for ∼50 years; however, the production sites of these positrons remains hard to identify. The observed morphology of positron annihilation gamma-rays provides information on the annihilation sites of these Galactic positrons. It is understood that the positrons responsible for the annihilation signal originate at MeV energies. The majority of sources of MeV positrons occupy the star-forming thin disk of the Milky Way. If positrons propagate far from their sources, we must develop accurate models of positron propagation through all interstellar medium (ISM phases in order to reveal the currently uncertain origin of these Galactic positrons. On the other hand, if positrons annihilate close to their sources, an alternative source of MeV positrons with a distribution that matches the annihilation morphology must be identified. In this work, I discuss the various models that have been developed to understand the origin of the 511 keV line from the direction of the Galactic bulge, and the propagation of positrons in the ISM.

Positron emission tomography (PET) in psychiatry

International Nuclear Information System (INIS)

Buchsbaum, M.S.

1984-01-01

In the past the approach to the brain has been necessarily indirect, employing peripheral fluids to assess central and regional neurochemical processes. Blood, urine, skin and muscle biopsy, and cerebrospinal fluid are valuable reflectors of the neurochemical and neuropharmacological activity of the brain, but are removed in time and place from disordered thought processes and diluted by the products of both functional and dysfunctional brain systems. Biopsy studies have helped in studying the functional disorders of organs like the liver, but they are destructive to the brain and less useful because unlike these organs, the brain has a regional variation in its chemistry. The experimental insights from animal studies focusing on the pharmacology of individual cell groups - in striatum or locus coeruleus, for example - cannot easily or unambigiously be applied to clinical populations. Positron emission tomography (PET) is a versatile approach utilizing the mathematics of x-ray transmission scanning (CT scanning) to produce slice images of radioisotope distribution. PET makes possible a wide range of metabolic studies. Positron emitters such as carbon-11 or fluorine-18 can be used to label glucose, amino acids, drugs, neurotransmitter precursors, and many other molecules and examine their distribution and fate in discrete cell groups

Neurological examination in small animals

Directory of Open Access Journals (Sweden)

Viktor Paluš

2014-03-01

Full Text Available This clinical review about the neurological examination in small animals describes the basics about the first steps of investigation when dealing with neurological patients. The knowledge of how to perform the neurological examination is important however more important is how to correctly interpret these performed tests. A step-by-step approach is mandatory and examiners should master the order and the style of performing these tests. Neurological conditions can be sometimes very distressing for owners and for pets that might not be the most cooperating. The role of a veterinary surgeon, as a professional, is therefore to collect the most relevant history, to examine a patient in a professional manner and to give to owners an educated opinion about the further treatment and prognosis. However neurological examinations might look challenging for many. But it is only the clinical application of neuroanatomy and neurophysiology to an every-day situation for practicing veterinarians and it does not require any specific in-to-depth knowledge. This clinical review is aimed not only to provide the information on how to perform the neurological examination but it is also aimed to appeal on veterinarians to challenge their daily routine and to start practicing on neurologically normal patients. This is the best and only way to differentiate between the normal and abnormal in a real situation.

The study of defects in metallic alloys by positron annihilation spectroscopy

International Nuclear Information System (INIS)

Romero, R.; Salgueiro, W.; Somoza, A.

1990-01-01

Positron annihilation spectroscopy (PAS) has become in a very useful non destructive testing to the study of condensed matter. Specially, in the last two decades, with the advent of solid state detectors and high-resolution time spectrometers. The basic information obtained with PAS in solid-state physics is on electronic structure in free defect materials. However, positron annihilation techniques (lifetime, angular correlation and Doppler broadening) have been succesfully applied to study crystal lattice defects with lower-than-average electron density, such as vacancies, small vacancy clusters, etc.. In this sense, information about: vacancy formation and migration energies, dislocations, grain boundaries, solid-solid phase transformation and radiation damage was obtained. In this work the application of the positron lifetime technique to study the thermal effects on a fine-grained superplastic Al-Ca-Zn alloy and the quenched-in defects in monocrystals of β Cu-Zn-Al alloy for several quenching temperatures is shown. (Author) [es

High intensity positron program at LLNL

International Nuclear Information System (INIS)

Asoka-Kumar, P.; Howell, R.; Stoeffl, W.; Carter, D.

1999-01-01

Lawrence Livermore National Laboratory (LLNL) is the home of the world close-quote s highest current beam of keV positrons. The potential for establishing a national center for materials analysis using positron annihilation techniques around this capability is being actively pursued. The high LLNL beam current will enable investigations in several new areas. We are developing a positron microprobe that will produce a pulsed, focused positron beam for 3-dimensional scans of defect size and concentration with submicron resolution. Below we summarize the important design features of this microprobe. Several experimental end stations will be available that can utilize the high current beam with a time distribution determined by the electron linac pulse structure, quasi-continuous, or bunched at 20 MHz, and can operate in an electrostatic or (and) magnetostatic environment. Some of the planned early experiments are: two-dimensional angular correlation of annihilation radiation of thin films and buried interfaces, positron diffraction holography, positron induced desorption, and positron induced Auger spectroscopy. copyright 1999 American Institute of Physics

PF slow positron source

International Nuclear Information System (INIS)

Shirakawa, A.; Enomoto, A.; Kurihara, T.

1993-01-01

A new slow-positron source is under construction at the Photon Factory. Positrons are produced by bombarding a tantalum rod with high-energy electrons; they are moderated in multiple tungsten vanes. We report here the present status of this project. (author)

Positron emission tomography in the diagnosis and staging of lung cancer

DEFF Research Database (Denmark)

Fischer, B M; Mortensen, J; Højgaard, L

2001-01-01

positron emission tomography (PET) and gamma-camera PET in the diagnostic investigation of non-small-cell lung cancer (NSCLC). A systematic literature search was carried out in the MEDLINE and EMBASE databases and the Cochrane Controlled Trials Register. We identified 55 original works on the diagnostic...

Positrons in amorphous alloys

International Nuclear Information System (INIS)

Moser, Pierre.

1981-07-01

Positron annihilation techniques give interesting informations about ''empty spaces'' in amorphous alloys. The results of an extensive research work on the properties of either pre-existing or irradiation induced ''empty spaces'' in four amorphous alloys are presented. The pre-existing empty spaces appear to be small vacancy-like defects. The irradiation induced defects are ''close pairs'' with widely distributed configurations. There is a strong interaction between vacancy like and interstitial like components. A model is proposed, which explains the radiation resistance mechanism of the amorphous alloys. An extensive joint research work to study four amorphous alloys, Fe 80 B 20 ,Fe 40 Ni 40 P 14 B 6 , Cu 50 Ti 50 , Pd 80 Si 20 , is summarized

Measurements of Positronium Formation Cross Sections for Positron-Kr, Xe Scattering

Science.gov (United States)

Kauppila, W. E.; Kwan, C. K.; Li, H.; Stein, T. S.; Zhou, S.

1997-04-01

Our experimental approach(S. Zhou et al., Phys. Rev. Lett. 73, 236 (1994).) for measuring Ps formation cross sections (Q_Ps) involves passing a variable energy positron beam through a gas scattering cell and detecting the 511 keV annihilation gamma rays resulting from the decay of para-Ps and from the interaction of ortho-Ps with the walls of the scattering cell. It is found that the Q_Ps curves for both Kr and Xe rise rapidly from their formation threshold energies of 7.2 and 5.3 eV, reach maxima within about 10 eV of their thresholds and then decrease to become rather small (less than 10% of the peak heights) above 100 eV. At the maxima Q_Ps accounts for more than 50% of the total scattering cross sections. There is some evidence of possible small scale structure in the Q_Ps curves between 10 and 100 eV. The present results are consistent with the prior measurements of Diana et al.( L.M. Diana et al., in "Atomic Physics with Positrons", edited by J.W. Humberston and E.A.G. Armour (Plenum, New York and London, 1987), p. 55; and in "Positron Annihilation", edited by L. Dorikens-Vanpraet et al. (World Scientific, Singapore, 1989), p. 311.) from near threshold to 70 eV for Kr and from 15 to 100 eV for Xe.

Positron spectroscopy of 2D materials using an advanced high intensity positron beam

Science.gov (United States)

McDonald, A.; Chirayath, V.; Lim, Z.; Gladen, R.; Chrysler, M.; Fairchild, A.; Koymen, A.; Weiss, A.

An advanced high intensity variable energy positron beam(~1eV to 20keV) has been designed, tested and utilized for the first coincidence Doppler broadening (CDB) measurements on 6-8 layers graphene on polycrystalline Cu sample. The system is capable of simultaneous Positron annihilation induced Auger electron Spectroscopy (PAES) and CDB measurements giving it unparalleled sensitivity to chemical structure at external surfaces, interfaces and internal pore surfaces. The system has a 3m flight path up to a micro channel plate (MCP) for the Auger electrons emitted from the sample. This gives a superior energy resolution for PAES. A solid rare gas(Neon) moderator was used for the generation of the monoenergetic positron beam. The positrons were successfully transported to the sample chamber using axial magnetic field generated with a series of Helmholtz coils. We will discuss the PAES and coincidence Doppler broadening measurements on graphene -Cu sample and present an analysis of the gamma spectra which indicates that a fraction of the positrons implanted at energies 7-60eV can become trapped at the graphene/metal interface. This work was supported by NSF Grant No. DMR 1508719 and DMR 1338130.

Investigation of granular impact using positron emission particle tracking

KAUST Repository

Marston, Jeremy O.

2015-04-01

We present results from an experimental study of granular impact using a combination of high-speed video and positron emission particle tracking (PEPT). The PEPT technique exploits the annihilation of photons from positron decay to determine the position of tracer particles either inside a small granular bed or attached to the object which impacts the bed. We use dense spheres as impactors and the granular beds are comprised of glass beads which are fluidised to achieve a range of different initial packing states. For the first time, we have simultaneously investigated both the trajectory of the sphere, the motion of particles in a 3-D granular bed and particles which jump into the resultant jet, which arises from the collapse of the cavity formed by the impacting sphere.

Positron depth profiling

International Nuclear Information System (INIS)

Coleman, P.

2001-01-01

Wide-ranging studies of defects below the surface of semiconductor structures have been performed at the University of Bath, in collaboration with the University of Surrey Centre for Ion Beam Applications and with members of research teams at a number of UK universities. Positron implantation has been used in conjunction with other spectroscopies such as RBS-channeling and SIMS, and electrical characterisation methods. Research has ranged from the development of a positron-based technique to monitor the in situ annealing of near-surface open-volume defects to the provision of information on defects to comprehensive diagnostic investigations of specific device structures. We have studied Si primarily but not exclusively; e.g., we have investigated ion-implanted SiC and SiO 2 /GaAs structures. Of particular interest are the applications of positron annihilation spectroscopy to ion-implanted semiconductors, where by linking ion dose to vacancy-type defect concentration one can obtain information on ion dose and uniformity with a sensitivity not achievable by standard techniques. A compact, user-friendly positron beam system is currently being developed at Bath, in collaboration with SCRIBA, with the intention of application in an industrial environment. (orig.)

Positron annihilation induced Auger electron spectroscopy and its implementation at accelerator based low energy positron factories

International Nuclear Information System (INIS)

Weiss, A.; Koeymen, A.R.; Mehl, D.; Lee, K.H.; Yang Gimo; Jensen, K.

1991-01-01

Positron annihilation induced auger electron spectroscopy (PAES) makes use of a beam of low energy positrons to excite Auger transitions by annihilating core electrons. The large secondary electron background usually present in Auger spectra can be eliminated by setting the positron beam energy well below the Auger electron energy. This allows true Auger lineshapes to be obtained. Further, because the positron is localized just outside the surface before it annihilates, PAES is extremely sensitive to the topmost atomic layer. Recent PAES results obtained at the University of Texas at Arlington will be presented. In addition, the use of high resolution energy analyzers with multichannel particle detection schemes to prevent problems due to the high data rates associated with accelerator based positron beams will be discussed. (orig.)

Nonlinear positron acoustic solitary waves

International Nuclear Information System (INIS)

Tribeche, Mouloud; Aoutou, Kamel; Younsi, Smain; Amour, Rabia

2009-01-01

The problem of nonlinear positron acoustic solitary waves involving the dynamics of mobile cold positrons is addressed. A theoretical work is presented to show their existence and possible realization in a simple four-component plasma model. The results should be useful for the understanding of the localized structures that may occur in space and laboratory plasmas as new sources of cold positrons are now well developed.

Positron emission tomography. Basic principles

International Nuclear Information System (INIS)

Rodriguez, Jose Luis; Massardo, Teresa; Gonzalez, Patricio

2001-01-01

The basic principles of positron emission tomography (PET) technique are reviewed. lt allows to obtain functional images from gamma rays produced by annihilation of a positron, a positive beta particle. This paper analyzes positron emitters production in a cyclotron, its general mechanisms, and the various detection systems. The most important clinical applications are also mentioned, related to oncological uses of fluor-l8-deoxyglucose

Compressive effect of the magnetic field on the positron range in commonly used positron emitters simulated using Geant4

Science.gov (United States)

Li, Chong; Cao, Xingzhong; Liu, Fuyan; Tang, Haohui; Zhang, Zhiming; Wang, Baoyi; Wei, Long

2017-11-01

The compressive effect of a magnetic field on the positron range from commonly used positron emitters in PET (Positron Emission Tomography) was simulated using the Geant4 toolkit with H2O as the environmental material. The compression of the positron range, which was different in the directions parallel and perpendicular to the magnetic field, showed finite final variation of relative change rate versus the magnetic field. The variation greatly depended on the positron-emission energy spectrum in the same medium. Furthermore, the volume of the positron annihilation point was dramatically compressed as the magnetic field was set in the range of 3-6T. It was more prominent for 82Rb , which is generally used as a positron source in PET technology.

Positron annihilation studies of mesoporous silica films using a slow positron beam

International Nuclear Information System (INIS)

He Chunqing; Muramatsu, Makoto; Ohdaira, Toshiyuki; Kinomura, Atsushi; Suzuki, Ryoichi; Ito, Kenji; Kabayashi, Yoshinori

2006-01-01

Positron annihilation lifetime spectra were measured for mesoporous silica films, which were synthesized using triblock copolymer (EO 106 PO 70 EO 106 ) as a structure-directing agent. Different positron lifetime spectra for the deposited and calcined films indicated the formation of meso-structure after calcination, which was confirmed by Fourier transform infrared (FTIR) spectra and field emission-scanning electron microscopy (FE-SEM) observation. Open porosity or pore interconnectivity of a silica film might be evaluated by a two-dimensional positron annihilation lifetime spectrum of an uncapped film. Pore sizes and their distributions in the silica films were found to be affected by thermal treatments

Positron annihilation spectroscopy

International Nuclear Information System (INIS)

Sundar, C.S.; Viswanathan, B.

1996-01-01

An overview of positron annihilation spectroscopy, the experimental techniques and its application to studies on defects and electronic structure of materials is presented. The scope of this paper is to present the requisite introductory material, that will enable a better appreciation of the subsequent specialized articles on the applications of positron annihilation spectroscopy to investigate various problems in materials science. (author). 31 refs., 3 figs

Positron Studies of Oxide-Semiconductor Structures

OpenAIRE

Uedono , A.; Wei , L.; Kawano , T.; Tanigawa , S.; Suzuki , R.; Ohgaki , H.; Mikado , T.

1995-01-01

The annihilation characteristics of positrons in SiO2 films grown on Si substrates were studied by using monoenergetic positron beams. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured as a function of incident positron energy for SiO2/Si structures fabricated by various oxidation techniques. From the measurements, it was found that the formation probability of positronium (Ps) atoms in SiO2 films strongly depends on the growth condition...

X-ray micro-tomography system for small-animal imaging with zoom-in imaging capability

International Nuclear Information System (INIS)

Chun, In Kon; Cho, Myung Hye; Lee, Sang Chul; Cho, Min Hyoung; Lee, Soo Yeol

2004-01-01

Since a micro-tomography system capable of μm-resolution imaging cannot be used for whole-body imaging of a small laboratory animal without sacrificing its spatial resolution, it is desirable for a micro-tomography system to have local imaging capability. In this paper, we introduce an x-ray micro-tomography system capable of high-resolution imaging of a local region inside a small animal. By combining two kinds of projection data, one from a full field-of-view (FOV) scan of the whole body and the other from a limited FOV scan of the region of interest (ROI), we have obtained zoomed-in images of the ROI without any contrast anomalies commonly appearing in conventional local tomography. For experimental verification of the zoom-in imaging capability, we have integrated a micro-tomography system using a micro-focus x-ray source, a 1248 x 1248 flat-panel x-ray detector, and a precision scan mechanism. The mismatches between the two projection data caused by misalignments of the scan mechanism have been estimated with a calibration phantom, and the mismatch effects have been compensated in the image reconstruction procedure. Zoom-in imaging results of bony tissues with a spatial resolution of 10 lp mm -1 suggest that zoom-in micro-tomography can be greatly used for high-resolution imaging of a local region in small-animal studies

RELIABILITY OF POSITRON EMISSION TOMOGRAPHY-COMPUTED TOMOGRAPHY IN EVALUATION OF TESTICULAR CARCINOMA PATIENTS.

Science.gov (United States)

Nikoletić, Katarina; Mihailović, Jasna; Matovina, Emil; Žeravica, Radmila; Srbovan, Dolores

2015-01-01

The study was aimed at assessing the reliability of 18F-fluorodeoxyglucose positron emission tomography-computed tomography scan in evaluation of testicular carcinoma patients. The study sample consisted of 26 scans performed in 23 patients with testicular carcinoma. According to the pathohistological finding, 14 patients had seminomas, 7 had nonseminomas and 2 patients had a mixed histological type. In 17 patients, the initial treatment was orchiectomy+chemotherapy, 2 patients had orchiectomy+chemotherapy+retroperitoneal lymph node dissection, 3 patients had orchiectomy only and one patient was treated with chemotherapy only. Abnormal computed tomography was the main cause for the oncologist to refer the patient to positron emission tomography-computed tomography scan (in 19 scans), magnetic resonance imaging abnormalities in 1 scan, high level oftumor markers in 3 and 3 scans were perforned for follow-up. Positron emission tomography-computed tomography imaging results were compared with histological results, other imaging modalities or the clinical follow-up of the patients. Positron emission tomography-computed tomography scans were positive in 6 and negative in 20 patients. In two patients, positron emission tomography-computed tomography was false positive. There were 20 negative positron emission omography-computed tomography scans perforned in 18 patients, one patient was lost for data analysis. Clinically stable disease was confirmed in 18 follow-up scans performed in 16 patients. The values of sensitivty, specificity, accuracy, and positive- and negative predictive value were 60%, 95%, 75%, 88% and 90.5%, respectively. A hgh negative predictive value obtained in our study (90.5%) suggests that there is a small possibility for a patient to have future relapse after normal positron emission tomography-computed tomography study. However, since the sensitivity and positive predictive value of the study ire rather low, there are limitations of positive

Depth-dependent positron annihilation in different polymers

Energy Technology Data Exchange (ETDEWEB)

Yang, J.; Zhang, P.; Cheng, G.D.; Li, D.X.; Wu, H.B.; Li, Z.X.; Cao, X.Z. [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Jia, Q.J. [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Yu, R.S. [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Wang, B.Y., E-mail: wangboy@ihep.ac.cn [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China)

2013-09-01

Depth-dependent positron annihilation Doppler broadening measurements were conducted for polymers with different chemical compositions. Variations of the S parameter with respect to incident positron energy were observed. For pure hydrocarbons PP, HDPE and oxygen-containing polymer PC, S parameter rises with increasing positron implantation depth. While for PI and fluoropolymers like PTFE, ETFE and PVF, S parameter decreases with higher positron energy. For chlorine-containing polymer PVDC, S parameter remains nearly constant at all incident positron energies. It is suggested that these three variation trends are resulted from a competitive effect between the depth-dependent positronium formation and the influence of highly electronegative atoms on positron annihilation characteristics.

Simulation of the annihilation emission of galactic positrons; Modelisation de l'emission d'annihilation des positrons Galactiques

Energy Technology Data Exchange (ETDEWEB)

Gillard, W

2008-01-15

Positrons annihilate in the central region of our Galaxy. This has been known since the detection of a strong emission line centered on an energy of 511 keV in the direction of the Galactic center. This gamma-ray line is emitted during the annihilation of positrons with electrons from the interstellar medium. The spectrometer SPI, onboard the INTEGRAL observatory, performed spatial and spectral analyses of the positron annihilation emission. This thesis presents a study of the Galactic positron annihilation emission based on models of the different interactions undergone by positrons in the interstellar medium. The models are relied on our present knowledge of the properties of the interstellar medium in the Galactic bulge, where most of the positrons annihilate, and of the physics of positrons (production, propagation and annihilation processes). In order to obtain constraints on the positrons sources and physical characteristics of the annihilation medium, we compared the results of the models to measurements provided by the SPI spectrometer. (author)

Experimentation with low-energy positron beams

International Nuclear Information System (INIS)

Mills, A.P. Jr.

1983-01-01

The capability of studying the interactions of positrons with surfaces has recently been exploited by using ultra-high-vacuum techniques. The result has been a new understanding of how positrons interact with surfaces and because of this we are now able to make much stronger fluxes of slow positrons. The higher beam strengths in turn are opening up new possibilities for experimentation on surfaces and solids and for studying the atomic physics of positronium and positron-molecule scattering at low energies. The lectures are intended to review some of the history of this subject and to outline the present state of our knowledge of experimentation with low-energy positron beams. (orig./TW)

Positron annihilation in vitreous silica glasses

International Nuclear Information System (INIS)

Uedono, Akira; Tanigawa, Shoichiro

1993-01-01

The annihilation characteristics of positrons in vitreous silica glasses (v-SiO 2 ) were studied by measurements of two-dimensional angular correlation of positron annihilation radiations and positron lifetime spectra. From the measurements, it was found that positrons and positronium (Ps) atoms mainly annihilate from trapped states by vacancy-type defects in v-SiO 2 . For v-SiO 2 specimens with cylindrical porous structures, annihilations of Ps with anisotropic momentum distributions were observed. This fact was attributed to the momentum uncertainty due to localization of Ps in a finite dimension of pores. This investigation showed possibilities for the detection of microstructures in v-SiO 2 by the positron annihilation technique. (author)

Positrons in ionic crystals

International Nuclear Information System (INIS)

Pareja, R.

1988-01-01

Positron annihilation experiments in ionic crystals are reviewed and their results are arranged. A discussion about the positron states in these materials is made in the light of these results and the different proposed models. The positronium in alkali halides is specially considered. (Author)

Clinical applications of positron emission tomography in breast cancer patients

International Nuclear Information System (INIS)

Roemer, W.; Avril, N.; Schwaiger, M.

1997-01-01

Increased glucose metabolism by malignant tissue can be visualized with positron emission tomography (PET), using the radiolabeled glucose analogue F-18 fluorodeoxyglucose (FDG). Depending on the criteria of image interpretation FDG-PET allows detection of breast cancer with a sensitivity of 68% to 94 % and a specificity of 84 % to 97 %. However, sensitivity to visualize small tumors (< 1 cm) is limited. Positron emission tomography demonstrates tumor involvement of regional lymph nodes with high accuracy, predominantly in patients with advanced breast cancer. The sensitivity for the detection of axillary lymph node metastases was 79% with a corresponding specificity of 96 %. Lymph node metastases could not be identified in four of six patients with small primary breast cancer (stage pT1), resulting in a sensitivity of only 33% in these patients. By visualizing primary tumors and metastases in one imaging procedure, PET imaging may allow the effective staging of breast cancer patients. Further studies are needed to define the role of scintigraphic techniques for the diagnostic work-up in patients. (author)

Pain control in small animalsControle da dor em pequenos animais

Directory of Open Access Journals (Sweden)

Julia Duarte Penter

2011-12-01

Full Text Available Pain is an unpleasant sensory or emotional experience that follows the application of a noxious stimulus. Can be experienced with or without the concomitant occurrence of physical stress signs, which occurs frequently in animals caused by trauma, systemic disease or surgical procedures. The control depends on length, where there are painful impulses and mental status of the animal. It is an important clinical condition, resulting in suffer that will affect quality life. This paper is a review of pathophysiology and pain control in small animals.A dor é uma experiência sensorial ou emocional desagradável que se segue à aplicação de um estímulo nocivo. Pode ser vivenciada com ou sem o acontecimento concomitante de sinais físicos de estresse, trauma, doença sistêmica ou procedimento cirúrgico. Seu controle depende de sua duração, de onde surgem os impulsos dolorosos e do estado de consciência do animal. É uma condição clinicamente importante, que resulta em sofrimento e afeta a qualidade de vida dos animais. O objetivo deste trabalho é a revisão da fisiopatologia e controle da dor em pequenos animais.

Positron annihilation in SiO 2-Si studied by a pulsed slow positron beam

Science.gov (United States)

Suzuki, R.; Ohdaira, T.; Uedono, A.; Kobayashi, Y.

2002-06-01

Positron and positronium (Ps) behavior in SiO 2-Si have been studied by means of positron annihilation lifetime spectroscopy (PALS) and age-momentum correlation (AMOC) spectroscopy with a pulsed slow positron beam. The PALS study of SiO 2-Si samples, which were prepared by a dry-oxygen thermal process, revealed that the positrons implanted in the Si substrate and diffused back to the interface do not contribute to the ortho-Ps long-lived component, and the lifetime spectrum of the interface has at least two components. From the AMOC study, the momentum distribution of the ortho-Ps pick-off annihilation in SiO 2, which shows broader momentum distribution than that of crystalline Si, was found to be almost the same as that of free positron annihilation in SiO 2. A varied interface model was proposed to interpret the results of the metal-oxide-semiconductor (MOS) experiments. The narrow momentum distribution found in the n-type MOS with a negative gate bias voltage could be attributed to Ps formation and rapid spin exchange in the SiO 2-Si interface. We have developed a two-dimensional positron lifetime technique, which measures annihilation time and pulse height of the scintillation gamma-ray detector for each event. Using this technique, the positronium behavior in a porous SiO 2 film, grown by a sputtering method, has been studied.

Theoretical calculations of positron lifetimes for metal oxides

International Nuclear Information System (INIS)

Mizuno, Masataka; Araki, Hideki; Shirai, Yasuharu

2004-01-01

Our recent positron lifetime measurements for metal oxides suggest that positron lifetimes of bulk state in metal oxides are shorter than previously reported values. We have performed theoretical calculations of positron lifetimes for bulk and vacancy states in MgO and ZnO using first-principles electronic structure calculations and discuss the validity of positron lifetime calculations for insulators. By comparing the calculated positron lifetimes to the experimental values, it wa found that the semiconductor model well reproduces the experimental positron lifetime. The longer positron lifetime previously reported can be considered to arise from not only the bulk but also from the vacancy induced by impurities. In the case of cation vacancy, the calculated positron lifetime based on semiconductor model is shorter than the experimental value, which suggests that the inward relaxation occurs around the cation vacancy trapping the positron. (author)

Detection of tokamak plasma positrons using annihilation photons

Energy Technology Data Exchange (ETDEWEB)

Guanying, Yu; Liu, Jian; Xie, Jinlin [University of Science and Technology, Hefei, Anhui, 230027 (China); Li, Jiangang, E-mail: j_li@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

2017-05-15

Highlights: • A design for detection of tokamak plasma positrons is given. • Identify the main obstacle toward experimental confirmation of fusion plasma positrons. • Signal to noise ratio in a plasma disruption is estimated. • Unique potential applications of fusion plasma positrons are discussed. - Abstract: A massive amount of positrons (plasma positrons), produced by the collision between runaway electrons and nuclei during fusion plasma disruption, was first predicted theoretically in 2003. To help confirm this prediction, we report here the design of an experimental system to detect tokamak plasma positrons. Because a substantial amount of positrons (material positrons) are produced when runaway electrons impact plasma-facing materials, we proposed maximizing the ratio of plasma to material positrons by inserting a thin carbon target at the plasma edge as a plasma positron bombing target and producing a plasma disruption scenario triggered by massive gas injection. Meanwhile, the coincidence detection of positron annihilation photons was used to filter out the noise of annihilation photons from locations other than the carbon target and that of bremsstrahlung photons near 511 keV. According to our simulation, the overall signal-to-noise ratio should be more than 10:1.

Time-dependent behavior of positrons in noble gases

International Nuclear Information System (INIS)

Wadehra, J.M.

1990-01-01

Both equilibrium and nonequilibrium behaviors of positrons in several noble gases are reviewed. Our novel procedure for obtaining the time-dependent behavior of various swarm parameters -- such as the positron drift velocity, average positron energy, positron annihilation rate (or equivalently Z eff ) etc. -- for positrons in pure ambient gases subjected to external electrostatic fields is described. Summaries of time-dependent as well as electric field-dependent results for positron swarms in various noble gases are presented. New time-dependent results for positron swarms in neon are also described in detail. 36 refs., 4 figs., 3 tabs

The Combination of In vivo 124I-PET and CT Small Animal Imaging for Evaluation of Thyroid Physiology and Dosimetry

Directory of Open Access Journals (Sweden)

Henrik H. El-Ali

2012-06-01

Full Text Available Objective: A thyroid rat model combining functional and anatomical information would be of great benefit for better modeling of thyroid physiology and for absorbed dose calculations. Our aim was to show that 124I-PET and CT small animal imaging are useful as a combined model for studying thyroid physiology and dose calculation. Methods: Seven rats were subjects for multiple thyroid 124I-imaging and CT-scans. S-values [mGy/MBqs] for different thyroid sizes were simulated. A phantom with spheres was designed for validation of performances of the small animal PET and CT imaging systems. Results: Small animal image-based measurements of the activity amount and the volumes of the spheres with a priori known volumes showed a good agreement with their corresponding actual volumes. The CT scans of the rats showed thyroid volumes from 34–70 mL. Conclusions: The wide span in volumes of thyroid glands indicates the importance of using an accurate volume-measuring technique such as the small animal CT. The small animal PET system was on the other hand able to accurately estimate the activity concentration in the thyroid volumes. We conclude that the combination of the PET and CT image information is essential for quantitative thyroid imaging and accurate thyroid absorbed dose calculation.

STTARR: a radiation treatment and multi-modal imaging facility for fast tracking novel agent development in small animal models

International Nuclear Information System (INIS)

Yeung, Ivan; McKee, Trevor; Jaffray, David; Hill, Richard

2014-01-01

Small animal models play a pivotal role in the pipeline development of novel agents and strategies in personalized cancer therapy. The Spatio-Temporal Targeting and Amplification of Radiation Response Program (STTARR) consists of an animal imaging and precision radiation facility designed to provide innovative biologic imaging and targeted radiation treatment strategies in small animals. The design is to mirror the imaging and radiation treatment facility in a modern cancer center. The STTARR features imaging equipment of small animal scale including CT, MRI, PET, SPECT, Optical devices as well as image guided irradiators. The fleet of imaging and irradiation equipment provides a platform for identification of biological targets of the specific molecular pathways that influence both tumor progression and a patient's response to radiation therapy. Examples will be given in the utilization of the imaging facilities for development in novel approaches in cancer therapy including a PET-FAZA study for hypoxia measurement in a pancreatic adenocarcinoma xenograft model. In addition, the cone-beam image guided small animal irradiator developed at our institute will also be described. The animal platform (couch) provides motion in 3 dimensions to position the animal to the isocentre of the beam. A pair of rotational arms supporting the X-ray/detector pair enables acquisition of cone-beam images of the animal which give rise to image guided precision of 0.5 mm. The irradiation energy ranges from 50 to 225 kVp at a dose rate from 10-400 cGy/min. The gantry is able to direct X-ray beam of different directions to give conformal radiation treatment to the animal. A dedicated treatment planning system is able to perform treatment planning and provide commonly used clinical metrics in the animal treatment plan. Examples will be given to highlight the use of the image guided irradiator for research of drug/irradiation regimen in animal models. (author)

Solvated Positron Chemistry. II

DEFF Research Database (Denmark)

Mogensen, O. E.

1979-01-01

The reaction of the hydrated positron, eaq+ with Cl−, Br−, and I− ions in aqueous solutions was studied by means of positron The measured angular correlation curves for [Cl−, e+], [Br−, e+, and [I−, e+] bound states were in good agreement with th Because of this agreement and the fact...... that the calculated positron wavefunctions penetrate far outside the X− ions in the [X−, e+] sta propose that a bubble is formed around the [X−, e+] state, similar to the Ps bubble found in nearly all liquids. F−ions did not react w Preliminary results showed that CN− ions react with eaq+ while OH−ions are non...... in the Cl− case) at higher concentrations. This saturation and the high-concentration effects-in the angular correlation results were interpreted as caused by rather complicated spur effects, wh It is proposed that spur electrons may pick off the positron from the [X−, e+ states with an efficiency which...

Radiation damage of polymers studied by positron annihilation. Positron and gamma-ray irradiation effects

International Nuclear Information System (INIS)

Suzuki, T.; Oki, Y.; Numajiri, M.; Miura, T.; Kondo, K.; Ito, Y.

1995-01-01

Positron irradiation effects on polypropylene (PP) have been studied using positron sources ( 22 Na) during positron annihilation (PA) experiments. The irradiation effect was measured by the intensity (I 3 ) of the long-lived component of positronium (Ps). At a low temperature of around 100 K, I 3 for unirradiated PP samples increased due to a termination of the thermal motion of the -CH 3 groups. However, the increase in I 3 for γ-ray irradiated samples was reduced in inverse proportion to the amount of irradiation. Although no increase in I 3 was observed for 1 MGy-irradiated PP with γ-rays, an increase was observed again after a 48 h irradiation by positrons emitted from 22 Na. This may be due to a reconstructing of the polymer chains. (author)

Effects of positron density and temperature on large amplitude ion-acoustic waves in an electron-positron-ion plasma

International Nuclear Information System (INIS)

Nejoh, Y.N.

1997-01-01

The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with positrons. We have presented the region of existence of the ion-acoustic waves by analysing the structure of the pseudopotential. The region of existence sensitively depends on the positron to electron density ratio, the ion to electron mass ratio and the positron to electron temperature ratio. It is shown that the maximum Mach number increases as the positron temperature increases and the region of existence of the ion-acoustic waves spreads as the positron temperature increases. 12 refs., 6 figs

Importance of non-local electron-positron correlations for positron annihilation characteristics in solids

International Nuclear Information System (INIS)

Rubaszek, A.

2001-01-01

Several methods to describe the electron-positron (e-p) correlation effects are used in calculations of positron annihilation characteristics in solids. The weighted density approximation (WDA), giving rise to the non-local, state-selective e-p correlation functions, is applied to calculate positron annihilation rates and e-p momentum densities in a variety of metals and silicon. The WDA results are compared to the results of other methods such as the independent particle model, local density approximation, generalised gradient approximation, and also to experiments. The importance of non-locality and state-dependence of the e-p correlation functions is discussed. (orig.)

Positron source based on the 48V isotope dedicated to positron lifetime spectroscopy

International Nuclear Information System (INIS)

Dryzek, Jerzy

2009-01-01

In the paper we consider application of the 48 V isotope as a source in the positron lifetime spectroscopy. The isotope was produced in the 48 Ti(p,n) 48 V reaction using 15 MeV proton beam. As a target the natural titanium thin plate was used. The measurements using the typical positron lifetime spectrometer have shown the usefulness of the source obtained for this application. Due to its properties, the source may be used for measurements of positron annihilation characteristics in high temperature or aggressive environments. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Applications of positron depth profiling

Energy Technology Data Exchange (ETDEWEB)

Hakvoort, R A

1993-12-23

In this thesis some contributions of the positron-depth profiling technique to materials science have been described. Following studies are carried out: Positron-annihilation measurements on neon-implanted steel; Void creation in silicon by helium implantation; Density of vacancy-type defects present in amorphous silicon prepared by ion implantation; Measurements of other types of amorphous silicon; Epitaxial cobalt disilicide prepared by cobalt outdiffusion. Positron-annihilation experiments on low-pressure CVD silicon-nitride films. (orig./MM).

Applications of positron depth profiling

International Nuclear Information System (INIS)

Hakvoort, R.A.

1993-01-01

In this thesis some contributions of the positron-depth profiling technique to materials science have been described. Following studies are carried out: Positron-annihilation measurements on neon-implanted steel; Void creation in silicon by helium implantation; Density of vacancy-type defects present in amorphous silicon prepared by ion implantation; Measurements of other types of amorphous silicon; Epitaxial cobalt disilicide prepared by cobalt outdiffusion. Positron-annihilation experiments on low-pressure CVD silicon-nitride films. (orig./MM)

On the empirical determination of positron trapping coefficient at nano-scale helium bubbles in steels irradiated in spallation target

Science.gov (United States)

Krsjak, Vladimir; Kuriplach, Jan; Vieh, Christiane; Peng, Lei; Dai, Yong

2018-06-01

In the present work, the specific positron trapping rate of small helium bubbles was empirically derived from positron annihilation lifetime spectroscopy (PALS) and transmission electron microscopy (TEM) studies of Fe9Cr martensitic steels. Both techniques are well known to be sensitive to nanometer-sized helium-filled cavities induced during irradiation in a mixed proton-neutron spectrum of spallation target. Complementary TEM and PALS studies show that positrons are being trapped to these defects at a rate of 1.2 ± 0.8 × 10-14 m3s-1. This suggests that helium bubbles in ferritic/martensitic steels are attractive traps for positrons comparable to mono-vacancies and quantitative analysis of the bubbles by PALS technique is plausible.

Evaluation of Timepix silicon detector for the detection of 18F positrons

Science.gov (United States)

Wang, Q.; Tous, J.; Liu, Z.; Ziegler, S.; Shi, K.

2014-05-01

Timepix is an evolving energy and position sensitive pixel detector. It consists of a silicon detector (sensitive layer 300 μm thick) bump-bonded to the Timepix readout chip developed by the Medipix2 collaboration. This study aims to test the feasibility of using the acquired energy and position signals from Timepix for positron imaging. The signals of the commonly used fluorine-18 PET (positron emission tomography) tracer [18F]FDG were measured using Timepix operated both in single particle counting (Medipix) and in time over threshold (TOT) modes. The spatial resolution (SR) was measured using the absorber edge method (AEM) and was calculated from the over-sampled line spread function. The track of a positron in the Timepix detector was characterized as a cluster and the energy weighted centroid of each cluster was considered as readout for the position of the positron incidence. The measurement results were compared with theoretical predictions using Monte-Carlo simulations. In addition, imaging of a tissue slice of a mouse heart was analysed with reference to standard phosphor plate imaging. Our results show that the SR was improved from 177.1±4.1 μm (centroid without energy weighting) to 155.5±3.1 μm μm (centroid with energy weighting). About 12% enhancement of SR was achieved with energy information in TOT mode. The sensitivity of Timepix was 0.35 cps/Bq based on the measurements. The measuring background and the ratio between detected positrons and gamma rays were also evaluated and were found to be consistent with theoretical predictions. A small enhancement of image quality was also achieved by applying energy information to the data of the measured tissue sample. Our results show that the inclusion of energy information could slightly enhance the positron measurement compared to without energy information and the Timepix provides a high SR and sensitivity for positron detection. Thus, Timepix is a potentially effective tool for 2D positron imaging.

78 FR 59624 - Guidance for Industry #223: Small Entity Compliance Guide-Declaring Color Additives in Animal...

Science.gov (United States)

2013-09-27

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Part 501 [Docket No. FDA-2013-D-1088] Guidance for Industry 223: Small Entity Compliance Guide--Declaring Color Additives... industry 223 entitled ``Small Entity Compliance Guide--Declaring Color Additives in Animal Foods.'' This...

Cone Beam X-Ray Luminescence Tomography Imaging Based on KA-FEM Method for Small Animals.

Science.gov (United States)

Chen, Dongmei; Meng, Fanzhen; Zhao, Fengjun; Xu, Cao

2016-01-01

Cone beam X-ray luminescence tomography can realize fast X-ray luminescence tomography imaging with relatively low scanning time compared with narrow beam X-ray luminescence tomography. However, cone beam X-ray luminescence tomography suffers from an ill-posed reconstruction problem. First, the feasibility of experiments with different penetration and multispectra in small animal has been tested using nanophosphor material. Then, the hybrid reconstruction algorithm with KA-FEM method has been applied in cone beam X-ray luminescence tomography for small animals to overcome the ill-posed reconstruction problem, whose advantage and property have been demonstrated in fluorescence tomography imaging. The in vivo mouse experiment proved the feasibility of the proposed method.

Coupler for surgery on small animals

Science.gov (United States)

Johnson, J. E., Jr.; Swartz, P. F.

1979-01-01

Minicoupler simplifies exchange of fluids with organs of laboratory animals enabling one person to perform surgery on experimental animals such as rats and mice. Innovation eliminates obstructing hands and instruments from areas of surgery.

Positron emission tomography

International Nuclear Information System (INIS)

Lindback, Stig

1995-01-01

Positron Emission Tomography (PET) is an advanced nuclear medicine technique used for research at major centres. Unique diagnostic information is obtained from tomographic measurements of the biochemistry and physiology of tissues and organs. In theory, diseases are related to biochemical changes and these can be observed with PET long before any anatomical changes are detectable. In PET the radioactive component is a positron-emitting isotope or 'tracer'. The positrons annihilate with electrons in the body to produce two gamma rays 180° apart; coincidence detection of these gammas provides a very efficient method of determining the spatial distribution of the radioisotope tracer. Because physiological measurements are usually required in a single imaging session, very short-lived isotopes are used to label the tracer molecules; isotope production and labelling is usually carried out in situ. The most commonly used radionuclides are carbon- 11 (half-life 20 minutes), nitrogen-13 (10 minutes), oxygen-15 (2 minutes), and fluorine-18 (110 minutes). A PET system has three major components: - a particle accelerator with targets for production of the positron-emitting isotopes; - chemistry modules for synthesis and labelling of the desired tracers; - and a PET camera for in-vivo measurements of the distribution of the tracer in the body

Positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Lindback, Stig [GEMS PET Systems AB, Uppsala (Sweden)

1995-07-15

Positron Emission Tomography (PET) is an advanced nuclear medicine technique used for research at major centres. Unique diagnostic information is obtained from tomographic measurements of the biochemistry and physiology of tissues and organs. In theory, diseases are related to biochemical changes and these can be observed with PET long before any anatomical changes are detectable. In PET the radioactive component is a positron-emitting isotope or 'tracer'. The positrons annihilate with electrons in the body to produce two gamma rays 180° apart; coincidence detection of these gammas provides a very efficient method of determining the spatial distribution of the radioisotope tracer. Because physiological measurements are usually required in a single imaging session, very short-lived isotopes are used to label the tracer molecules; isotope production and labelling is usually carried out in situ. The most commonly used radionuclides are carbon- 11 (half-life 20 minutes), nitrogen-13 (10 minutes), oxygen-15 (2 minutes), and fluorine-18 (110 minutes). A PET system has three major components: - a particle accelerator with targets for production of the positron-emitting isotopes; - chemistry modules for synthesis and labelling of the desired tracers; - and a PET camera for in-vivo measurements of the distribution of the tracer in the body.

Absolute quantitative total-body small-animal SPECT with focusing pinholes

International Nuclear Information System (INIS)

Wu, Chao; Have, Frans van der; Vastenhouw, Brendan; Beekman, Freek J.; Dierckx, Rudi A.J.O.; Paans, Anne M.J.

2010-01-01

In pinhole SPECT, attenuation of the photon flux on trajectories between source and pinholes affects quantitative accuracy of reconstructed images. Previously we introduced iterative methods that compensate for image degrading effects of detector and pinhole blurring, pinhole sensitivity and scatter for multi-pinhole SPECT. The aim of this paper is (1) to investigate the accuracy of the Chang algorithm in rodents and (2) to present a practical Chang-based method using body outline contours obtained with optical cameras. Here we develop and experimentally validate a practical method for attenuation correction based on a Chang first-order method. This approach has the advantage that it is employed after, and therefore independently from, iterative reconstruction. Therefore, no new system matrix has to be calculated for each specific animal. Experiments with phantoms and animals were performed with a high-resolution focusing multi-pinhole SPECT system (U-SPECT-II, MILabs, The Netherlands). This SPECT system provides three additional optical camera images of the animal for each SPECT scan from which the animal contour can be estimated. Phantom experiments demonstrated that an average quantification error of -18.7% was reduced to -1.7% when both window-based scatter correction and Chang correction based on the body outline from optical images were applied. Without scatter and attenuation correction, quantification errors in a sacrificed rat containing sources with known activity ranged from -23.6 to -9.3%. These errors were reduced to values between -6.3 and +4.3% (with an average magnitude of 2.1%) after applying scatter and Chang attenuation correction. We conclude that the modified Chang correction based on body contour combined with window-based scatter correction is a practical method for obtaining small-animal SPECT images with high quantitative accuracy. (orig.)

Positron probes of the Ge(1 0 0) surface: The effects of surface reconstructions and electron-positron correlations on positron trapping and annihilation characteristics