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Sample records for age-dependent voxel phantoms

  1. The reference phantoms: voxel vs polygon.

    Science.gov (United States)

    Kim, C H; Yeom, Y S; Nguyen, T T; Wang, Z J; Kim, H S; Han, M C; Lee, J K; Zankl, M; Petoussi-Henss, N; Bolch, W E; Lee, C; Chung, B S

    2016-06-01

    The International Commission on Radiological Protection (ICRP) reference male and female adult phantoms, described in Publication 110, are voxel phantoms based on whole-body computed tomography scans of a male and a female patient, respectively. The voxel in-plane resolution and the slice thickness, of the order of a few millimetres, are insufficient for proper segmentation of smaller tissues such as the lens of the eye, the skin, and the walls of some organs. The calculated doses for these tissues therefore present some limitations, particularly for weakly penetrating radiation. Similarly, the Publication 110 phantoms cannot represent 8-40-µm-thick target regions in respiratory or alimentary tract organs. Separate stylised models have been used to represent these tissues for calculation of the ICRP reference dose coefficients (DCs). ICRP Committee 2 recently initiated a research project, the ultimate goal of which is to convert the Publication 110 phantoms to a high-quality polygon-mesh (PM) format, including all source and target regions, even those of the 8-40-µm-thick alimentary and respiratory tract organs. It is expected that the converted phantoms would lead to the same or very similar DCs as the Publication 110 reference phantoms for penetrating radiation and, at the same time, provide more accurate DCs for weakly penetrating radiation and small tissues. Additionally, the reference phantoms in the PM format would be easily deformable and, as such, could serve as a starting point to create phantoms of various postures for use, for example, in accidental dose calculations. This paper will discuss the current progress of the phantom conversion project and its significance for ICRP DC calculations.

  2. Construction tool and suitability of voxel phantom for skin dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, Paula C.G.; Siqueira, Paulo T.D.; Fonseca, Gabriel P.; Yoriyaz, Helio, E-mail: ptsiquei@ipen.b, E-mail: hyoriyaz@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    This paper describes a new software tool called 'SkinVop' which was developed to enable accurate voxel phantom skin dosimetry. A voxel phantom is a model used to describe human anatomy in a realistic way in radiation transport codes. This model is a three-dimensional representation of the human body in the form of an array of identification numbers that are arranged in a 3D matrix. Each entry in this array represents a voxel (volume element) directly associated to the units of picture resolution (pixel) of medical images. Currently, these voxel phantoms, in association with the transport code MCNP (Monte Carlo N-Particle), have provided subsidies to the planning systems used on the hospital routine, once they afford accurate and personalized estimative of dose distribution. However, these assessments are limited to geometric representations of organs and tissues in the voxel phantom, which do not discriminates some thin body structure, such as the skin. In this context, to enable accurate dosimetric skin dose assessment by the MCNP code, it was developed this new software tool that discriminates this region with thickness and localization in the voxel phantoms similar to the real. This methodology consists in manipulating the skin volume elements by segmenting and subdividing them in different thicknesses. A graphical user interface was designed to fulfill display the modified voxel model. This methodology is extremely useful once the skin dose is inaccurately assessed of current hospital system planning, justified justly by its small thickness. (author)

  3. Preparing a voxel-simulator of Alderson Rando physical phantom

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    Boia, Leonardo S.; Martins, Maximiano C.; Silva, Ademir X., E-mail: lboia@con.ufrj.br, E-mail: ademir@con.ufrj.br [Programa de Engenharia Nuclear (PEN/COPPE/UFRJ). Universidade Federal do Rio de Janeiro, RJ (Brazil); Salmon Junior, Helio A., E-mail: heliosalmon@coinet.com.br [COI - Clinicas Oncologicas Integradas, MD.X Barra Medical Center, Rio de Janeiro, RJ (Brazil); Soares, Alessandro F.N.S., E-mail: afacure@cnen.gov.br [Comissao Nacional de Engenharia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    There are, nowadays, sorts of anthropomorphycal phantoms which are used for simulation of radiation transport by the matter and also the deposition of energy in such radiation in human tissues and organs, because an in-vitro dosimetry becomes very either complicated or even impossible in some cases. In the present work we prepared a computational phantom in voxels based on computational tomography of Rando-Alderson. This phantom is one of the most known human body simulators on the scope of ionizing radiation dosimetry, and it is used for radioprotection issues and dosimetry from radiotherapy and brachytherapy treatments as well. The preparation of a voxel simulator starts with the image acquisition by a tomograph found at COI/RJ (Clinicas Oncologicas Integradas). The images were generated with 1mm cuts and collected for analysis. After that step the images were processed in SAPDI (Sistema Automatizado de Processamento Digital de Imagem) in order to amplify the images regions intending to facilitate the task in their segmentation. SAPDI is based on parameters described by Hounsfield scale. After that, it has begun discretization of elements in IDs voxels using Scan2MCNP software - which converts images to a sequential text file containing the voxels' IDs ready to be introduced into MCNPX input; however, this set can be turned to a voxel's IDs matrix and used in other Monte Carlo codes, such as Geant4, PENELOPE and EGSnrc. Finished this step, the simulator is able to simulate with accurate geometry the physical phantom. It's possible to study a large number of cases by computational techniques of geometry's insertions of tumors and TLDs, which makes this simulator a research material useful for a lot of subjects. (author)

  4. Influence of voxel size on specific absorbed fractions and S-values in a mouse voxel phantom.

    Science.gov (United States)

    Mohammadi, A; Kinase, S

    2011-02-01

    Photon and electron specific absorbed fractions (SAFs) and S-values have been evaluated using mouse voxel phantoms. In voxel phantoms, it is important to choose the voxel size carefully since it affects the accuracy of results. In this study, two mouse voxel phantoms were constructed, with cubic voxels, one with 0.1-mm sides and the other with 0.4-mm sides. The sources were considered to be distributed uniformly in the main organs and the radiation transport was simulated using the Monte Carlo code EGS4. It was found that the effect of voxel size on SAFs for self-irradiation was not high (voxel size was investigated on S-values for some beta emitters such as (131)I, (153)Sm, (188)Re and (90)Y.

  5. Development of a voxel phantom of Japanese adult male in upright posture

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Endo, A.; Saito, K. [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Noguchi, H. [Safety Administration Department, Japan Atomic Energy Agency, 4-49 Muramatsu, Tokai-mura, Naka-gun, Ibaraki-ken 319-1184 (Japan); Emoto, Y.; Koga, S. [Fujita Health University, School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake-shi, Aichi-ken 470-1192 (Japan)

    2007-07-01

    A Japanese voxel phantom in upright posture, JM2, has been developed on the basis of CT images of a healthy Japanese adult male. Body characteristics of JM2 were compared with those of the supine voxel phantom, JM, previously developed using CT images of the same person. Differences were found in the shapes of the spine and lower abdomen and the locations of several organs such as kidneys, liver and stomach between the two phantoms. Specific absorbed fractions (SAFs) for 24 target and 11 sources organs were calculated for monoenergetic photon ranging from 0.01 to 4 MeV. It was found that the SAFs for the kidneys as source organ and the lower large intestine wall as target organ in JM2 were significantly higher than those in JM for all photon energies. The differences of the SAFs between the two phantoms were attributed to the differences in the organ distance and organ geometry depending on the posture. (authors)

  6. Effective dose evaluation for BNCT brain tumor treatment based on voxel phantoms.

    Science.gov (United States)

    Wang, Jeng-Ning; Lee, Kuo-Wei; Jiang, Shiang-Huei

    2014-06-01

    For BNCT treatments, in addition to tumor target doses, non-negligible doses will result in all the remaining organs of the body. This work aims to evaluate the effective dose as well as the average absorbed doses of each of organs of patients with brain tumor treated in the BNCT epithermal neutron beam at THOR. The effective doses were evaluated according to the definitions of ICRP Publications 60 and 103 for the reference male and female computational phantoms developed in ICRP Publication 110 by using the MCNP5 Monte Carlo code with the THOR-Y09 beam source. The effective dose acquired in this work was compared with the results of our previous work calculated for an adult hermaphrodite mathematical phantom. It was found that the effective dose for the female voxel phantom is larger than that for the male voxel phantom by a factor of 1.2-1.5 and the effective dose for the voxel phantom is larger than that for the mathematical phantom by a factor of 1.3-1.6. For a typical brain tumor BNCT, the effective dose was calculated to be 1.51Sv and the average absorbed dose for eye lenses was 1.07Gy.

  7. Multi-resolution voxel phantom modeling: a high-resolution eye model for computational dosimetry

    Science.gov (United States)

    Caracappa, Peter F.; Rhodes, Ashley; Fiedler, Derek

    2014-09-01

    Voxel models of the human body are commonly used for simulating radiation dose with a Monte Carlo radiation transport code. Due to memory limitations, the voxel resolution of these computational phantoms is typically too large to accurately represent the dimensions of small features such as the eye. Recently reduced recommended dose limits to the lens of the eye, which is a radiosensitive tissue with a significant concern for cataract formation, has lent increased importance to understanding the dose to this tissue. A high-resolution eye model is constructed using physiological data for the dimensions of radiosensitive tissues, and combined with an existing set of whole-body models to form a multi-resolution voxel phantom, which is used with the MCNPX code to calculate radiation dose from various exposure types. This phantom provides an accurate representation of the radiation transport through the structures of the eye. Two alternate methods of including a high-resolution eye model within an existing whole-body model are developed. The accuracy and performance of each method is compared against existing computational phantoms.

  8. An Eye Model for Computational Dosimetry Using A Multi-Scale Voxel Phantom

    Science.gov (United States)

    Caracappa, Peter F.; Rhodes, Ashley; Fiedler, Derek

    2014-06-01

    The lens of the eye is a radiosensitive tissue with cataract formation being the major concern. Recently reduced recommended dose limits to the lens of the eye have made understanding the dose to this tissue of increased importance. Due to memory limitations, the voxel resolution of computational phantoms used for radiation dose calculations is too large to accurately represent the dimensions of the eye. A revised eye model is constructed using physiological data for the dimensions of radiosensitive tissues, and is then transformed into a high-resolution voxel model. This eye model is combined with an existing set of whole body models to form a multi-scale voxel phantom, which is used with the MCNPX code to calculate radiation dose from various exposure types. This phantom provides an accurate representation of the radiation transport through the structures of the eye. Two alternate methods of including a high-resolution eye model within an existing whole body model are developed. The accuracy and performance of each method is compared against existing computational phantoms.

  9. S values for 131I based on the ICRP adult voxel phantoms

    Science.gov (United States)

    Lamart, Stephanie; Simon, Steven L.; Bouville, Andre; Moroz, Brian E.; Lee, Choonsik

    2016-01-01

    To improve the estimates of organ doses from nuclear medicine procedures using 131I, the authors calculated a comprehensive set of 131I S values, defined as absorbed doses in target tissues per unit of nuclear transition in source regions, for different source and target combinations. The authors used the latest reference adult male and female voxel phantoms published by the International Commission on Radiological Protection (ICRP Publication 110) and the 131I photon and electron spectra from the ICRP Publication 107 to perform Monte Carlo radiation transport calculations using MCNPX2.7 to compute the S values. For each phantom, the authors simulated 55 source regions with an assumed uniform distribution of 131I. They computed the S values for 42 target tissues directly, without calculating specific absorbed fractions. From these calculations, the authors derived a comprehensive set of S values for 131I for 55 source regions and 42 target tissues in the ICRP male and female voxel phantoms. Compared with the stylised phantoms from Oak Ridge National Laboratory (ORNL) that consist of 22 source regions and 24 target regions, the new data set includes 1662 additional S values corresponding to additional combinations of source–target tissues that are not available in the stylised phantoms. In a comparison of S values derived from the ICRP and ORNL phantoms, the authors found that the S values to the radiosensitive tissues in the ICRP phantoms were 1.1 (median, female) and 1.3 (median, male) times greater than the values based on the ORNL phantoms. However, for several source–target pairs, the difference was up to 10-fold. The new set of S values can be applied prospectively or retrospectively to the calculation of radiation doses in adults internally exposed to 131I, including nuclear medicine patients treated for thyroid cancer or hyperthyroidism. PMID:25829162

  10. All about FAX: a Female Adult voXel phantom for Monte Carlo calculation in radiation protection dosimetry.

    Science.gov (United States)

    Kramer, R; Khoury, H J; Vieira, J W; Loureiro, E C M; Lima, V J M; Lima, F R A; Hoff, G

    2004-12-01

    The International Commission on Radiological Protection (ICRP) has created a task group on dose calculations, which, among other objectives, should replace the currently used mathematical MIRD phantoms by voxel phantoms. Voxel phantoms are based on digital images recorded from scanning of real persons by computed tomography or magnetic resonance imaging (MRI). Compared to the mathematical MIRD phantoms, voxel phantoms are true to the natural representations of a human body. Connected to a radiation transport code, voxel phantoms serve as virtual humans for which equivalent dose to organs and tissues from exposure to ionizing radiation can be calculated. The principal database for the construction of the FAX (Female Adult voXel) phantom consisted of 151 CT images recorded from scanning of trunk and head of a female patient, whose body weight and height were close to the corresponding data recommended by the ICRP in Publication 89. All 22 organs and tissues at risk, except for the red bone marrow and the osteogenic cells on the endosteal surface of bone ('bone surface'), have been segmented manually with a technique recently developed at the Departamento de Energia Nuclear of the UFPE in Recife, Brazil. After segmentation the volumes of the organs and tissues have been adjusted to agree with the organ and tissue masses recommended by ICRP for the Reference Adult Female in Publication 89. Comparisons have been made with the organ and tissue masses of the mathematical EVA phantom, as well as with the corresponding data for other female voxel phantoms. The three-dimensional matrix of the segmented images has eventually been connected to the EGS4 Monte Carlo code. Effective dose conversion coefficients have been calculated for exposures to photons, and compared to data determined for the mathematical MIRD-type phantoms, as well as for other voxel phantoms.

  11. Fast Monte Carlo simulation on a voxelized human phantom deformed to a patient

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, G.; Deniz, O.; Carrascosa, C. B.; Delgado, J. M.; Brualla, L. [E.T.S.I. Industriales, Universidad de Castilla-La Mancha, Avenida Camilo Jose Cela s/n, E-13071 Ciudad Real (Spain); Instituto Oncologico (Grupo IMO), Hospital La Milagrosa, Modesto Lafuente, 14, E-28010 Madrid (Spain); NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Hufelandstr. 55, D-45122 Essen (Germany)

    2009-11-15

    Purpose: A method for performing fast simulations of absorbed dose using a patient's computerized tomography (CT) scan without explicitly relying on a calibration curve is presented. Methods: The method is based on geometrical deformations performed on a standard voxelized human phantom. This involves spatially transforming the human phantom to align it with the patient CT image. Since the chemical composition and density of each voxel are given in the phantom data, a calibration curve is not used in the proposed method. For this study, the Monte Carlo (MC) code PENELOPE has been used as the simulation of reference. The results obtained with PENELOPE simulations are compared to those obtained with PENFAST and with the collapsed cone convolution algorithm implemented in a commercial treatment planning system. Results: The comparisons of the absorbed doses calculated with the different algorithms on two patient CTs and the corresponding deformed phantoms show a maximum distance to agreement of 2 mm, and in general, the obtained absorbed dose distributions are compatible within the reached statistical uncertainty. The validity of the deformation method for a broad range of patients is shown using MC simulations in random density phantoms. A PENFAST simulation of a 6 MV photon beam impinging on a patient CT reaches 2% statistical uncertainty in the absorbed dose, in a 0.1 cm{sup 3} voxel along the central axis, in 10 min running on a single core of a 2.8 GHz CPU. Conclusions: The proposed method of the absorbed dose calculation in a deformed voxelized phantom allows for dosimetric studies in the geometry of a patient CT scan. This is due to the fact that the chemical composition and material density of the phantom are known. Furthermore, simulation using the phantom geometry can provide dosimetric information for each organ. The method can be used for quality assurance procedures. In relation to PENFAST, it is shown that a purely condensed-history algorithm (class

  12. Effects of CT based Voxel Phantoms on Dose Distribution Calculated with Monte Carlo Method

    Institute of Scientific and Technical Information of China (English)

    Chen Chaobin; Huang Qunying; Wu Yican

    2005-01-01

    A few CT-based voxel phantoms were produced to investigate the sensitivity of Monte Carlo simulations of X-ray beam and electron beam to the proportions of elements and the mass densities of the materials used to express the patient's anatomical structure. The human body can be well outlined by air, lung, adipose, muscle, soft bone and hard bone to calculate the dose distribution with Monte Carlo method. The effects of the calibration curves established by using various CT scanners are not clinically significant based on our investigation. The deviation from the values of cumulative dose volume histogram derived from CT-based voxel phantoms is less than 1% for the given target.

  13. MicroCT-Based Skeletal Models for Use in Tomographic Voxel Phantoms for Radiological Protection

    Energy Technology Data Exchange (ETDEWEB)

    Bolch, Wesley [Univ. of Florida, Gainesville, FL (United States)

    2010-03-30

    The University of Florida (UF) proposes to develop two high-resolution image-based skeletal dosimetry models for direct use by ICRP Committee 2’s Task Group on Dose Calculation in their forthcoming Reference Voxel Male (RVM) and Reference Voxel Female (RVF) whole-body dosimetry phantoms. These two phantoms are CT-based, and thus do not have the image resolution to delineate and perform radiation transport modeling of the individual marrow cavities and bone trabeculae throughout their skeletal structures. Furthermore, new and innovative 3D microimaging techniques will now be required for the skeletal tissues following Committee 2’s revision of the target tissues of relevance for radiogenic bone cancer induction. This target tissue had been defined in ICRP Publication 30 as a 10-μm cell layer on all bone surfaces of trabecular and cortical bone. The revised target tissue is now a 50-μm layer within the marrow cavities of trabecular bone only and is exclusive of the marrow adipocytes. Clearly, this new definition requires the use of 3D microimages of the trabecular architecture not available from past 2D optical studies of the adult skeleton. With our recent acquisition of two relatively young cadavers (males of age 18-years and 40-years), we will develop a series of reference skeletal models that can be directly applied to (1) the new ICRP reference voxel man and female phantoms developed for the ICRP, and (2) pediatric phantoms developed to target the ICRP reference children. Dosimetry data to be developed will include absorbed fractions for internal beta and alpha-particle sources, as well as photon and neutron fluence-to-dose response functions for direct use in external dosimetry studies of the ICRP reference workers and members of the general public

  14. Dose conversion coefficients for Chinese reference adult male and female voxel phantoms from idealized neutron exposures

    CERN Document Server

    Liu, Huan; Qiu, Rui; Yang, Yue; Pan, Yu-Xi; Liu, Li-Ye

    2015-01-01

    A new set of fluence-to-dose conversion coefficients based on the Chinese reference adult voxel phantoms CRAM and CRAF are presented for six idealized external neutron exposures from 10-8 MeV to 20 MeV. The voxel phantoms CRAM and CRAF were adjusted from the previous phantoms CNMAN and CNWM respectively, and the masses of individual organs have been adjusted to the Chinese reference data. The calculation of organ-absorbed doses and effective doses were performed with the Monte Carlo transport code MCNPX. The resulting dose conversion coefficients were compared with those published in ICRP Publication 116, which represents the reference Caucasian. The organ-absorbed dose conversion coefficients of most organs are in good agreement with the results in ICRP Publication 116, however, obvious discrepancies are observed for some organs and certain geometries. For neutrons with energies above 2 MeV, the effective dose conversion coefficients of Chinese reference adult are almost identical to those of ICRP Publicatio...

  15. Prostate dose calculations for permanent implants using the MCNPX code and the Voxels phantom MAX

    Energy Technology Data Exchange (ETDEWEB)

    Reis Junior, Juraci Passos dos; Silva, Ademir Xavier da, E-mail: jjunior@con.ufrj.b, E-mail: Ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Facure, Alessandro N.S., E-mail: facure@cnen.gov.b [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2010-07-01

    This paper presents the modeling of 80, 88 and 100 of {sup 125}I seeds, punctual and volumetric inserted into the phantom spherical volume representing the prostate and prostate phantom voxels MAX. Starting values of minimum and maximum activity, 0.27 mCi and 0.38 mCi, respectively, were simulated in the Monte Carlo code MCNPX in order to determine whether the final dose, according to the integration of the equation of decay at time t = 0 to t = {infinity} corresponds to the default value set by the AAPM 64 which is 144 Gy. The results showed that consider sources results in doses exceeding the percentage discrepancy of the default value of 200%, while volumetric consider sources result in doses close to 144 Gy. (author)

  16. The creation of voxel phantoms for the purpose of environmental dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Caffrey, E.; Higley, K. [Oregon State University (United States)

    2014-07-01

    Basic geometric shapes have long been used as the standard for calculating radiation dose rates in non-human biota (NHB). Regulation standards have seen a shift recently, towards protection of NHB as its own endpoint. As such, there has been a growing interest in improving the calculations for NHB dose rates. To address calls for additional data, the development of voxelized models for the International Commission on Radiological Protection's (ICRP) twelve reference animal and plants (RAP) has been undertaken. Voxel models of a crab (Metacarcinus magister), flatfish (Pleuronectiformes), trout (Oncorhynchus mykiss), worm (Lumbricina), honey bee (Apis), frog (Anura), and rat, (Rattus) have been created to date. The purpose of this submission is to describe the processes of creating these voxel phantoms from radiological imaging data (i.e., Computed Tomography (CT), Magnetic Resonance Imaging (MRI), etc.). CT/MRI images of the organism are obtained and uploaded into a software package capable of segmenting the images (3D Doctor was used for the crab, flatfish, trout, worm, and honey bee). On each image slice, individual organs and other relevant anatomical features (e.g. bones or other structural tissues) are identified and segmented. Once segmentation is complete, a boundary file that describes the positioning of the organs and tissues in lattice geometry format is exported into software called Voxelizer, created by the Human Monitoring Laboratory of Canada. This software writes the boundary file geometry into an input file for Monte Carlo N-Particle (MCNP) based simulations. The user can then add appropriate materials, densities, and a desired source term. These simulations yield absorbed fraction (AF) values that are used in subsequent dose calculations with environmental concentration data. AFs are now available for the crab, flatfish, trout, worm, and honey bee at twelve photon and nine electron energies, consistent with ICRP AFs for human dosimetry

  17. Application of digital image processing for the generation of voxels phantoms for Monte Carlo simulation.

    Science.gov (United States)

    Boia, L S; Menezes, A F; Cardoso, M A C; da Rosa, L A R; Batista, D V S; Cardoso, S C; Silva, A X; Facure, A

    2012-01-01

    This paper presents the application of a computational methodology for optimizing the conversion of medical tomographic images in voxel anthropomorphic models for simulation of radiation transport using the MCNP code. A computational system was developed for digital image processing that compresses the information from the DICOM medical image before it is converted to the Scan2MCNP software input file for optimization of the image data. In order to validate the computational methodology, a radiosurgery treatment simulation was performed using the Alderson Rando phantom and the acquisition of DICOM images was performed. The simulation results were compared with data obtained with the BrainLab planning system. The comparison showed good agreement for three orthogonal treatment beams of (60)Co gamma radiation. The percentage differences were 3.07%, 0.77% and 6.15% for axial, coronal and sagital projections, respectively.

  18. A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phantom

    Energy Technology Data Exchange (ETDEWEB)

    Bellezzo, M.; Do Nascimento, E.; Yoriyaz, H., E-mail: mbellezzo@gmail.br [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    As the most accurate method to estimate absorbed dose in radiotherapy, Monte Carlo method has been widely used in radiotherapy treatment planning. Nevertheless, its efficiency can be improved for clinical routine applications. In this paper, we present the CUBMC code, a GPU-based Mc photon transport algorithm for dose calculation under the Compute Unified Device Architecture platform. The simulation of physical events is based on the algorithm used in Penelope, and the cross section table used is the one generated by the Material routine, als present in Penelope code. Photons are transported in voxel-based geometries with different compositions. To demonstrate the capabilities of the algorithm developed in the present work four 128 x 128 x 128 voxel phantoms have been considered. One of them is composed by a homogeneous water-based media, the second is composed by bone, the third is composed by lung and the fourth is composed by a heterogeneous bone and vacuum geometry. Simulations were done considering a 6 MeV monoenergetic photon point source. There are two distinct approaches that were used for transport simulation. The first of them forces the photon to stop at every voxel frontier, the second one is the Woodcock method, where the photon stop in the frontier will be considered depending on the material changing across the photon travel line. Dose calculations using these methods are compared for validation with Penelope and MCNP5 codes. Speed-up factors are compared using a NVidia GTX 560-Ti GPU card against a 2.27 GHz Intel Xeon CPU processor. (Author)

  19. Development of a voxel phantom specific for simulation of eye brachytherapy; Desenvolvimeto de um fantoma de voxel especifico para simulacao de braquiterapia ocular

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcilio S.; Lima, Fernando R.A., E-mail: msilveira.fisica@gmail.com, E-mail: falima@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear; Vieira, Jose W., E-mail: jose-wilson59@live.com [lnstituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil)

    2013-11-01

    The ophthalmic brachytherapy involves inserting a plate with seeds of radioactive material in the patient's eye for the treatment of tumors. The radiation dose to be taken by the patient is prescribed by physicians and time of application of the material is calculated from calibration curves supplied by the manufacturers of the plates. To estimate the dose absorbed by the patient, in a series of diagnostic tests, it is necessary to perform simulations using a computational model of exposure. These models are composed primarily by a anthropomorphic phantom, and a Monte Carlo code. The coupling of a phantom voxel whole body to a Monte Carlo code is a complex process because the computer model simulations with exposure takes time, knowledge of the code used and various adjustments to be implemented. The problem is aggravated even more complex when you want to radiate one region of the body. In this work we developed a phantom, specifically the region containing the eyeball, from MASH (Male Adult voxel). This model was coupled to the Monte Carlo code EGSnrc (Electron Gamma Shower) together with an algorithm simulator source of I-125 , considering only its effect of higher energy range.

  20. Selected organ dose conversion coefficients for external photons calculated using ICRP adult voxel phantoms and Monte Carlo code FLUKA.

    Science.gov (United States)

    Patni, H K; Nadar, M Y; Akar, D K; Bhati, S; Sarkar, P K

    2011-11-01

    The adult reference male and female computational voxel phantoms recommended by ICRP are adapted into the Monte Carlo transport code FLUKA. The FLUKA code is then utilised for computation of dose conversion coefficients (DCCs) expressed in absorbed dose per air kerma free-in-air for colon, lungs, stomach wall, breast, gonads, urinary bladder, oesophagus, liver and thyroid due to a broad parallel beam of mono-energetic photons impinging in anterior-posterior and posterior-anterior directions in the energy range of 15 keV-10 MeV. The computed DCCs of colon, lungs, stomach wall and breast are found to be in good agreement with the results published in ICRP publication 110. The present work thus validates the use of FLUKA code in computation of organ DCCs for photons using ICRP adult voxel phantoms. Further, the DCCs for gonads, urinary bladder, oesophagus, liver and thyroid are evaluated and compared with results published in ICRP 74 in the above-mentioned energy range and geometries. Significant differences in DCCs are observed for breast, testis and thyroid above 1 MeV, and for most of the organs at energies below 60 keV in comparison with the results published in ICRP 74. The DCCs of female voxel phantom were found to be higher in comparison with male phantom for almost all organs in both the geometries.

  1. Cancer risk estimation in Digital Breast Tomosynthesis using GEANT4 Monte Carlo simulations and voxel phantoms.

    Science.gov (United States)

    Ferreira, P; Baptista, M; Di Maria, S; Vaz, P

    2016-05-01

    The aim of this work was to estimate the risk of radiation induced cancer following the Portuguese breast screening recommendations for Digital Mammography (DM) when applied to Digital Breast Tomosynthesis (DBT) and to evaluate how the risk to induce cancer could influence the energy used in breast diagnostic exams. The organ doses were calculated by Monte Carlo simulations using a female voxel phantom and considering the acquisition of 25 projection images. Single organ cancer incidence risks were calculated in order to assess the total effective radiation induced cancer risk. The screening strategy techniques considered were: DBT in Cranio-Caudal (CC) view and two-view DM (CC and Mediolateral Oblique (MLO)). The risk of cancer incidence following the Portuguese screening guidelines (screening every two years in the age range of 50-80years) was calculated by assuming a single CC DBT acquisition view as standalone screening strategy and compared with two-view DM. The difference in the total effective risk between DBT and DM is quite low. Nevertheless in DBT an increase of risk for the lung is observed with respect to DM. The lung is also the organ that is mainly affected when non-optimal beam energy (in terms of image quality and absorbed dose) is used instead of an optimal one. The use of non-optimal energies could increase the risk of lung cancer incidence by a factor of about 2.

  2. A software to digital image processing to be used in the voxel phantom development.

    Science.gov (United States)

    Vieira, J W; Lima, F R A

    2009-11-15

    Anthropomorphic models used in computational dosimetry, also denominated phantoms, are based on digital images recorded from scanning of real people by Computed Tomography (CT) or Magnetic Resonance Imaging (MRI). The voxel phantom construction requests computational processing for transformations of image formats, to compact two-dimensional (2-D) images forming of three-dimensional (3-D) matrices, image sampling and quantization, image enhancement, restoration and segmentation, among others. Hardly the researcher of computational dosimetry will find all these available abilities in single software, and almost always this difficulty presents as a result the decrease of the rhythm of his researches or the use, sometimes inadequate, of alternative tools. The need to integrate the several tasks mentioned above to obtain an image that can be used in an exposure computational model motivated the development of the Digital Image Processing (DIP) software, mainly to solve particular problems in Dissertations and Thesis developed by members of the Grupo de Pesquisa em Dosimetria Numérica (GDN/CNPq). Because of this particular objective, the software uses the Portuguese idiom in their implementations and interfaces. This paper presents the second version of the DIP, whose main changes are the more formal organization on menus and menu items, and menu for digital image segmentation. Currently, the DIP contains the menus Fundamentos, Visualizações, Domínio Espacial, Domínio de Frequências, Segmentações and Estudos. Each menu contains items and sub-items with functionalities that, usually, request an image as input and produce an image or an attribute in the output. The DIP reads edits and writes binary files containing the 3-D matrix corresponding to a stack of axial images from a given geometry that can be a human body or other volume of interest. It also can read any type of computational image and to make conversions. When the task involves only an output image

  3. SU-E-CAMPUS-I-02: Estimation of the Dosimetric Error Caused by the Voxelization of Hybrid Computational Phantoms Using Triangle Mesh-Based Monte Carlo Transport

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C [Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD (United States); Badal, A [U.S. Food ' Drug Administration (CDRH/OSEL), Silver Spring, MD (United States)

    2014-06-15

    Purpose: Computational voxel phantom provides realistic anatomy but the voxel structure may result in dosimetric error compared to real anatomy composed of perfect surface. We analyzed the dosimetric error caused from the voxel structure in hybrid computational phantoms by comparing the voxel-based doses at different resolutions with triangle mesh-based doses. Methods: We incorporated the existing adult male UF/NCI hybrid phantom in mesh format into a Monte Carlo transport code, penMesh that supports triangle meshes. We calculated energy deposition to selected organs of interest for parallel photon beams with three mono energies (0.1, 1, and 10 MeV) in antero-posterior geometry. We also calculated organ energy deposition using three voxel phantoms with different voxel resolutions (1, 5, and 10 mm) using MCNPX2.7. Results: Comparison of organ energy deposition between the two methods showed that agreement overall improved for higher voxel resolution, but for many organs the differences were small. Difference in the energy deposition for 1 MeV, for example, decreased from 11.5% to 1.7% in muscle but only from 0.6% to 0.3% in liver as voxel resolution increased from 10 mm to 1 mm. The differences were smaller at higher energies. The number of photon histories processed per second in voxels were 6.4×10{sup 4}, 3.3×10{sup 4}, and 1.3×10{sup 4}, for 10, 5, and 1 mm resolutions at 10 MeV, respectively, while meshes ran at 4.0×10{sup 4} histories/sec. Conclusion: The combination of hybrid mesh phantom and penMesh was proved to be accurate and of similar speed compared to the voxel phantom and MCNPX. The lowest voxel resolution caused a maximum dosimetric error of 12.6% at 0.1 MeV and 6.8% at 10 MeV but the error was insignificant in some organs. We will apply the tool to calculate dose to very thin layer tissues (e.g., radiosensitive layer in gastro intestines) which cannot be modeled by voxel phantoms.

  4. An accelerator-based epithermal neutron beam design for BNCT and dosimetric evaluation using a voxel head phantom.

    Science.gov (United States)

    Lee, Deok-jae; Han, Chi Young; Park, Sung Ho; Kim, Jong Kyung

    2004-01-01

    The beam shaping assembly design has been investigated in order to improve the epithermal neutron beam for accelerator-based boron neutron capture therapy in intensity and quality, and dosimetric evaluation for the beams has been performed using both mathematical and voxel head phantoms with MCNP runs. The neutron source was assumed to be produced from a conventional 2.5 MeV proton accelerator with a thick (7)Li target. The results indicate that it is possible to enhance epithermal neutron flux remarkably as well as to embody a good spectrum shaping to epithermal neutrons only with the proper combination of moderator and reflector. It is also found that a larger number of thermal neutrons can reach deeply into the brain and, therefore, can reduce considerably the treatment time for brain tumours. Consequently, the epithermal neutron beams designed in this study can treat more effectively deep-seated brain tumours.

  5. Design, fabrication, and implementation of voxel-based 3D printed textured phantoms for task-based image quality assessment in CT

    Science.gov (United States)

    Solomon, Justin; Ba, Alexandre; Diao, Andrew; Lo, Joseph; Bier, Elianna; Bochud, François; Gehm, Michael; Samei, Ehsan

    2016-03-01

    In x-ray computed tomography (CT), task-based image quality studies are typically performed using uniform background phantoms with low-contrast signals. Such studies may have limited clinical relevancy for modern non-linear CT systems due to possible influence of background texture on image quality. The purpose of this study was to design and implement anatomically informed textured phantoms for task-based assessment of low-contrast detection. Liver volumes were segmented from 23 abdominal CT cases. The volumes were characterized in terms of texture features from gray-level co-occurrence and run-length matrices. Using a 3D clustered lumpy background (CLB) model, a fitting technique based on a genetic optimization algorithm was used to find the CLB parameters that were most reflective of the liver textures, accounting for CT system factors of spatial blurring and noise. With the modeled background texture as a guide, a cylinder phantom (165 mm in diameter and 30 mm height) was designed, containing 20 low-contrast spherical signals (6 mm in diameter at targeted contrast levels of ~3.2, 5.2, 7.2, 10, and 14 HU, 4 repeats per signal). The phantom was voxelized and input into a commercial multi-material 3D printer (Object Connex 350), with custom software for voxel-based printing. Using principles of digital half-toning and dithering, the 3D printer was programmed to distribute two base materials (VeroWhite and TangoPlus, nominal voxel size of 42x84x30 microns) to achieve the targeted spatial distribution of x-ray attenuation properties. The phantom was used for task-based image quality assessment of a clinically available iterative reconstruction algorithm (Sinogram Affirmed Iterative Reconstruction, SAFIRE) using a channelized Hotelling observer paradigm. Images of the textured phantom and a corresponding uniform phantom were acquired at six dose levels and observer model performance was estimated for each condition (5 contrasts x 6 doses x 2 reconstructions x 2

  6. Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Mariana, E-mail: marianabaptista@ctn.ist.utl.pt; Di Maria, Salvatore; Barros, Sílvia; Vaz, Pedro [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, km 139,7, Bobadela LRS 2695-066 (Portugal); Figueira, Catarina [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University, Belfast BT7 1NN (United Kingdom); Sarmento, Marta; Orvalho, Lurdes [Serviço de Imagiologia, Hospital da Luz, Avenida Lusíada, 100, Lisboa 1500-650 (Portugal)

    2015-07-15

    Purpose: Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to study the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens{sup ®}) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. Methods: For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 –34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom (“Laura”), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Results: Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode

  7. Calibration Human Voxel Phantoms for In Vivo Measurement of ''2 sup 4 sup 1 Am in Bone at the Whole Body Counter Facility of CIEMAT

    CERN Document Server

    Moraleda, M; Navarro, J F; Navarro, T

    2002-01-01

    The Whole Body Counting facility of CIEMAT is capable of carrying out In-Vivo measurements of radionuclides emitting X-rays and low energy gamma radiation internally deposited in the body. The system to use for this purpose consists of flour Low energy Germanium (LeGe) Camberra detectors working in the energy range from 10 to 1000 keV. Physical phantoms with a known contamination in the organ of interest are normally used for the calibration of the LEGe detection system. In this document we present a calibration method using the Monte Carlo technique (MCNP4C) over a voxel phantom obtained from a computerized tomography of a real human head. The phantom consists of 104017 (43x59x41) cubic voxels, 4 mn on each side, os specific tissues, but for this simulation only two types are taken into account: adipose tissue and hard bone. The skull is supposed to be contaminated with ''241 Am and the trajectories of the photons are simulated till they reach the germanium detectors. The detectors were also simulated in det...

  8. Calibration Human Voxel Phantoms for In Vivo Measurement of ''241 Am in Bone at the Whole Body Counter Facility of CIEMAT

    Energy Technology Data Exchange (ETDEWEB)

    Moraleda, M.; Lopez, M. A.; Gomez Ros, J. M.; Navarro, T.; Navarro, J. F.

    2002-07-01

    The Whole Body Counting facility of CIEMAT is capable of carrying out In-Vivo measurements of radionuclides emitting X-rays and low energy gamma radiation internally deposited in the body. The system to use for this purpose consists of flour Low energy Germanium (LeGe) Camberra detectors working in the energy range from 10 to 1000 keV. Physical phantoms with a known contamination in the organ of interest are normally used for the calibration of the LEGe detection system. In this document we present a calibration method using the Monte Carlo technique (MCNP4C) over a voxel phantom obtained from a computerized tomography of a real human head. The phantom consists of 104017 (43x59x41) cubic voxels, 4 mn on each side, os specific tissues, but for this simulation only two types are taken into account: adipose tissue and hard bone. The skull is supposed to be contaminated with ''241 Am and the trajectories of the photons are simulated till they reach the germanium detectors. The detectors were also simulated in detail to obtain a good agreement with the reality. In order to verify the accuracy of this procedure to reproduce the experiments, the MCNP results are compared with laboratory measurements of a head phantom simulating an internal contamination of 1000 Bq of ''241 Am deposited in bone. Different relative positions source-detector were tried to look for the best countring geometry for measurement of a contaminated skull. Efficiency values are obtained and compared, resulting in the validation of the mathematical method for the assessment of internal contamination of American deposited in skeleton. (Author) 16 refs.

  9. Second generation anthropomorphic physical phantom for mammography and DBT: Incorporating voxelized 3D printing and inkjet printing of iodinated lesion inserts

    Science.gov (United States)

    Sikaria, Dhiraj; Musinsky, Stephanie; Sturgeon, Gregory M.; Solomon, Justin; Diao, Andrew; Gehm, Michael E.; Samei, Ehsan; Glick, Stephen J.; Lo, Joseph Y.

    2016-03-01

    Physical phantoms are needed for the evaluation and optimization of new digital breast tomosynthesis (DBT) systems. Previously, we developed an anthropomorphic phantom based on human subject breast CT data and fabricated using commercial 3D printing. We now present three key advancements: voxelized 3D printing, photopolymer material doping, and 2D inkjet printing of lesion inserts. First, we bypassed the printer's control software in order to print in voxelized form instead of conventional STL surfaces, thus improving resolution and allowing dithering to mix the two photopolymer materials into arbitrary proportions. We demonstrated ability to print details as small as 150μm, and dithering to combine VeroWhitePlus and TangoPlus in 10% increments. Second, to address the limited attenuation difference among commercial photopolymers, we evaluated a beta sample from Stratasys with increased TiO2 doping concentration up to 2.5%, which corresponded to 98% breast density. By spanning 36% to 98% breast density, this doubles our previous contrast. Third, using inkjet printers modified to print with iopamidol, we created 2D lesion patterns on paper that can be sandwiched into the phantom. Inkjet printing has advantages of being inexpensive and easy, and more contrast can be delivered through overprinting. Printing resolution was maintained at 210 μm horizontally and 330 μm vertically even after 10 overprints. Contrast increased linearly with overprinting at 0.7% per overprint. Together, these three new features provide the basis for creating a new anthropomorphic physical breast phantom with improved resolution and contrast, as well as the ability to insert 2D lesions for task-based assessment of performance.

  10. Two adult human voxel phantoms based on polygon mesh surfaces; Dois fantomas construidos a partir de superficies mesh representando uma mulher adulta e um homem adulto

    Energy Technology Data Exchange (ETDEWEB)

    Cassola, Vagner F.; Kramer, Richard; Khoury, Helen J. [Universidade Federal de Pernambuco (UFPE), Recife (Brazil). Dept. de Energia Nuclear], e-mail: rkramer@uol.com.br; Lima, Vanildo J.M. [Universidade Federal de Pernambuco (UFPE), Recife (Brazil). Dept. de Anatomia

    2010-03-15

    Among computational models used in radiation protection, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images, became very popular in recent years. Although being a true to nature representation of the scanned individual the scanning is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the anatomy of a person in upright standing position, which in turn can influence absorbed or equivalent dose estimates. This study proposes a method for human phantom design using tools recently developed in the areas of computer graphics and animated films and applies them to the creation and modeling of artificial 3D human organs and tissues. Two models, a male and a female adult human phantom have been developed based on anatomical atlases, observing at the same time the anatomical specifications published by the International Commission on Radiological Protection for the male and female reference adult. The phantoms are called FAX{sub A}A (Female Adult voXel{sub A}verage-Average) and MAX{sub A}A (Male Adult voXel{sub A}verage-Average) because they represent female and male adults with average weight and average height. (author)

  11. Development of an improved approach to radiation treatment therapy using high-definition patient-specific voxel phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Ward, R.C.; Ryman, J.C.; Worley, B.A.; Stallings, D.C. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    Through an internally funded project at Oak Ridge National Laboratory, a high-resolution phantom was developed based on the National Library of Medicine`s Visible Human Data. Special software was written using the interactive data language (IDL) visualization language to automatically segment and classify some of the organs and the skeleton of the Visible Male. A high definition phantom consisting of nine hundred 512 x 512 slices was constructed of the entire torso. Computed tomography (CT) images of a patient`s tumor near the spine were scaled and morphed into the phantom model to create a patient-specific phantom. Calculations of dose to the tumor and surrounding tissue were then performed using the patient-specific phantom.

  12. Application of Voxel Phantoms to Study the Influence of Heterogeneous Distribution of Actinides in Lungs on In Vivo Counting Calibration Factors Using Animal Experimentations

    Energy Technology Data Exchange (ETDEWEB)

    Lamart, S.; Pierrat, N.; De Carlan, L.; Franck, D. [IRSN/DRPH/SDI/LEDI, BP 17, F-92 262 Fontenay-aux-Roses (France); Dudoignon, N. [IRSN/DRPH/SRBE/LRPAT, BP 17, F-92 262 Fontenay-aux-Roses (France); Rateau, S.; Van der Meeren, A.; Rouit, E. [CEA/DSV/DRR/SRCA/LRT BP no 12, F-91680 Bruyeres-le-Chatel (France); Bottlaender, M. [CEA/SHFJ, 4, place du General Leclerc F-91400 Orsay (France)

    2006-07-01

    Calibration of lung counting system dedicated to retention assessment of actinides in the lungs remains critical due to large uncertainties in calibration factors. Among them, the detector positioning, the chest wall thickness and composition (muscle/fat) assessment, and the distribution of the contamination are the main parameters influencing the detector response. In order to reduce these uncertainties, a numerical approach based on the application of voxel phantoms (numerical phantoms based on tomographic images, CT or MRI) associated to a Monte-Carlo code (namely M.C.N.P.) was developed. It led to the development of a dedicated tool, called O.E.D.I.P.E., that allows to easily handle realistic voxel phantoms for the simulation of in vivo measurement (or dose calculation, application that will not be presented in this paper). The goal of this paper is to present our study of the influence of the lung distribution on calibration factors using both animal experimentations and our numerical method. Indeed, physical anthropomorphic phantoms used for calibration always consider a uniform distribution of the source in the lungs, which is not true in many contamination conditions. The purpose of the study is to compare the response of the measurement detectors using a real distribution of actinide particles in the lungs, obtained from animal experimentations, with the homogeneous one considered as the reference. This comparison was performed using O.E.D.I.P.E. that can almost simulate any source distribution. A non human primate was contaminated heterogeneously by intra-tracheal administration of actinide oxide. After euthanasia, gamma spectrometry measurements were performed on the pulmonary lobes to obtain the distribution of the contamination in the lungs. This realistic distribution was used to simulate an heterogeneous contamination in the numerical phantom of the non human primate, which was compared with a simulation of an homogeneous contamination presenting the

  13. Evaluation of the fluence to dose conversion coefficients for high energy neutrons using a voxel phantom coupled with the GEANT4 code

    CERN Document Server

    Paganini, S

    2005-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from Galactic cosmic radiation. Crews of future high-speed commercial flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the male adult voxels phantom MAX, developed in the Nuclear Energy Department of Pernambuco Federal University in Brazil, has been coupled with the Monte Carlo simulation code GEANT4. This toolkit, distributed and upgraded from the international scientific community of CERN/Switzerland, simulates thermal to ultrahigh energy neutrons transport and interactions in the matter. The high energy neutrons are pointed as the component that contribute about 70% of the neutron effective dose that represent the 35% to 60% total dose at aircraft altitude. In this research calculations of conversion coefficients from fluence to effective dose are performed for neutrons of energies from 100 MeV ...

  14. Effect of iodine contrast agent concentration on cerebrovascular dose for synchrotron radiation microangiography based on a simple mouse head model and a voxel mouse head phantom by Monte Carlo simulation.

    Science.gov (United States)

    Lin, Hui; Jing, Jia; Lu, Yi-Fan; Xie, Cong; Lin, Xiao-Jie; Yang, Guo-Yuan

    2016-01-01

    Effective setting strategies using Monte Carlo simulation are presented to mitigate the irradiation damage in synchrotron radiation microangiography (SRA). A one-dimensional mouse head model and a segmented voxel phantom mouse head were simulated using the EGSnrc/DOSXYZnrc code to investigate the dose enhancement effect of an iodine contrast agent irradiated by a monochromatic synchrotron radiation source. The influence of the iodine concentration, vessel width and depth, protection with and without the skull layer, and various incident X-ray energies were all simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated. The dose enhancement ratio depended little on the irradiation depth, but strongly and linearly increasing on iodine concentration. The protection given by the skull layer cannot be ignored in SRA because a 700 µm-thick skull can decrease the dose by 10%. The incident X-ray energy can affect the dose significantly. Compared with a dose of 33.2 keV for 50 mgI ml(-1), a dose of 32.7 keV decreased by 38%, whereas a dose of 33.7 keV increased by 69.2% and the variation strengthened more with enhanced iodine concentration. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depended little on the iodine voxel volume ratio but strongly on the iodine concentration. To decrease the damage caused by the dose in SRA, a high-Z contrast agent should be used as little as possible and irradiation of the injection site of the contrast agent should be avoided immediately after the injection. The fragile vessel containing iodine should avoid being closely irradiated. Avoiding irradiating through a thin (or no) skull region, or attaching a thin equivalent material on the outside for protection are better methods. An incident X-ray energy as low as possible should be used as long as the SRA image quality is ensured

  15. Two animated adult human voxel phantoms based on polygon mesh surfaces;Dois fantomas animados construidos a partir de superficies mesh representando um mulher adulta e um homem adulto

    Energy Technology Data Exchange (ETDEWEB)

    Cassola, Vagner F.; Kramer, Richard; Khoury, Helen J. [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Lima, Vanildo J.M. [Universidade Federal de Pernambuco (DA/UFPE), Recife, PE (Brazil). Dept. de Anatomia

    2009-07-01

    Among computational models used in radiation protection, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images, became very popular in recent years. Although being a true to nature representation of the scanned individual the scanning is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the anatomy of a person in upright standing position, which in turn can influence absorbed or equivalent dose estimates. This study proposes a method for human phantom design using tools recently developed in the areas of computer graphics and animated films and applies them to the creation and modelling of artificial 3 D human organs and tissues. Two animated models, a male and a female adult human phantom have been developed based on anatomical atlases, observing at the same time the anatomical specifications published by the International Commission on Radiological Protection for the male and female reference adult. The phantoms are called FAX{sub A}A (Female Adult voXel{sub A}verage-Average) and MAX{sub A}A (Male Adult voXel{sub A}verage-Average) because they represent female and male adults with average weight and average height. (author)

  16. A software to edit voxel phantoms and to calculate conversion coefficients for radiation protection; Um software para editar fantomas de voxels e calcular coeficientes de conversao para a protecao radiologica

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, J.W. [Centro Federal de Educacao Tecnologica de Pernambuco (CEFET/PE), Recife, PE (Brazil); Stosic, B. [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil); Lima, F.R.A. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Kramer, R.; Santos, A.M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Lima, V.J.M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Anatomia

    2005-07-01

    The MAX and FAX phantoms have been developed based on a male and female, respectively, adult body from ICRP and coupled to the Monte Carlo code (EGS4). These phantoms permit the calculating of the equivalent dose in organs and tissues of the human body for the radiation protection purposes . In the constructing of these anthropomorphic models, the software developed called FANTOMAS, which performs tasks as file format conversion, filtering 2D and 3D images, exchange of identifying numbers of organs, body mass adjustments based in volume, resampling of 2D and 3D images, resize images, preview consecutive slices of the phantom, running computational models of exposure FANTOMA/EGS4 and viewing graphics of conversion factors between equivalent dose and a measurable dosimetric quantity. This paper presents the main abilities of FANTOMAS and uses the MAX and/or FAX to exemplify some procedures.

  17. Construction of a computational exposure model for dosimetric calculations using the EGS4 Monte Carlo code and voxel phantoms; Construcao de um modelo computacional de exposicao para calculos dosimetricos utilizando o codigo Monte Carlo EGS4 e fantomas de voxels

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Jose Wilson

    2004-07-15

    The MAX phantom has been developed from existing segmented images of a male adult body, in order to achieve a representation as close as possible to the anatomical properties of the reference adult male specified by the ICRP. In computational dosimetry, MAX can simulate the geometry of a human body under exposure to ionizing radiations, internal or external, with the objective of calculating the equivalent dose in organs and tissues for occupational, medical or environmental purposes of the radiation protection. This study presents a methodology used to build a new computational exposure model MAX/EGS4: the geometric construction of the phantom; the development of the algorithm of one-directional, divergent, and isotropic radioactive sources; new methods for calculating the equivalent dose in the red bone marrow and in the skin, and the coupling of the MAX phantom with the EGS4 Monte Carlo code. Finally, some results of radiation protection, in the form of conversion coefficients between equivalent dose (or effective dose) and free air-kerma for external photon irradiation are presented and discussed. Comparing the results presented with similar data from other human phantoms it is possible to conclude that the coupling MAX/EGS4 is satisfactory for the calculation of the equivalent dose in radiation protection. (author)

  18. Estimation of specific absorbed fractions for selected organs due to photons emitted by activity deposited in the human respiratory tract using ICRP/ICRU male voxel phantom in FLUKA.

    Science.gov (United States)

    Patni, H K; Akar, D K; Nadar, M Y; Ghare, V P; Rao, D D; Sarkar, P K

    2013-01-01

    The ICRP/ICRU adult male reference voxel phantom incorporated in Monte Carlo code FLUKA is used for estimating specific absorbed fractions (SAFs) for photons due to the presence of internal radioactive contamination in the human respiratory tract (RT). The compartments of the RT, i.e. extrathoracic (ET1 and ET2) and thoracic (bronchi, bronchioles, alveolar interstitial) regions, lymph nodes of both regions and lungs are considered as the source organs. The nine organs having high tissue weighting factors such as colon, lungs, stomach wall, breast, testis, urinary bladder, oesophagus, liver and thyroid and the compartments of the RT are considered as target organs. Eleven photon energies in the range of 15 keV to 4 MeV are considered for each source organ and the computed SAF values are presented in the form of tables. For the target organs in the proximity of the source organ including the source organ itself, the SAF values are relatively higher and decrease with increase in energy. As the distance between source and target organ increases, SAF values increase with energy and reach maxima depending on the position of the target organ with respect to the source organ. The SAF values are relatively higher for the target organs with smaller masses. Large deviations are seen in computed SAF values from the existing MIRD phantom data for most of the organs. These estimated SAF values play an important role in the estimation of equivalent dose to various target organs of a worker due to intake by inhalation pathway.

  19. Dose Coefficient Calculation of External Exposure of Radionuclides Based on Chinese Reference Voxel Phantom%基于中国参考人体素模型环境外照射剂量转换系数的计算

    Institute of Scientific and Technical Information of China (English)

    路伟; 武祯; 邱睿; 李春艳; 杨博; 李君利

    2016-01-01

    Dose coefficients for external photon radiation are widely used for assessment of radiation dose to public and workers due to ground surface contamination and air immersion of radionuclides released in nuclear accidents. Dose coefficients based on Chinese reference voxel phantom were presented. Photons that incident into the cylinder, which is slightly larger than phantom, is simulated using Geant4, including distributions of angle, height and energy of photons; Secondly, photons are sampled on surface of cylinder around Chinese Reference Male/Female Voxel Phantom with MCNPX 2�4�k from the above source, dose coefficients of 20 initial gamma ray energies, from 15keV to 10 MeV, are calculated. Thirdly, dose coefficients of 68 important nuclides are evaluated by combining of decay data from ICRP 107 and photon coefficients using cubic⁃spline fitting. GB/T 17982⁃2000 shows an overestimation for ground contamination while an underestimation of high Z nuclides for air immersion compared to our results.%基于中国参考人体素模型计算地面污染和空气浸没情况下环境外照射剂量转换系数,主要用于核事故情况下公众及工作人员有效剂量的快速估算。首先,采用二次源项方法,基于Geant4模拟进入人体周围圆柱面入射光子的高度、角度和能量分布;其次,利用中国参考人体素模型和二次源项结果作为MCNPX模拟的输入项,计算15 keV至10 MeV能量范围内20组单能光子外照射剂量转换系数,和文献数据吻合;最后,利用ICRP第107报告核素衰变程序并对单能光子外照射剂量转换系数进行插值,计算了核事故情况下68种常见核素外照射剂量转换系数。与本文结果对比,国标中用于快速估算人员受照剂量转换系数值在地表沉积情况下偏保守,而空气浸没下中高Z放射性核素则偏低。

  20. Study of the influence of radionuclide biokinetics on in vivo counting using voxel phantoms; Etude de l'influence de la biocinetique des radionucleides sur la mesure anthroporadiametrique a l'aide de fantomes numeriques voxelises

    Energy Technology Data Exchange (ETDEWEB)

    Lamart, St.

    2008-10-15

    The in vivo measurement is an efficient method to estimate the retention of activity in case of internal contamination. However, it is currently limited by the use of physical phantoms for the calibration, not enabling to reproduce neither the morphology of the measured person nor the actual distribution of the contamination. The current method of calibration therefore leads to significant systematic uncertainties on the quantification of the contamination. To improve the in vivo measurement, the Laboratory of Internal Dose Assessment (LEDI, IRSN) has developed an original numerical calibration method with the OEDIPE software. It is based on voxel phantoms created from the medical images of persons, and associated with the MCNPX Monte Carlo code of particle transport. The first version of this software enabled to model simple homogeneous sources and to better estimate the systematic uncertainties in the lung counting of actinides due to the detector position and to the heterogeneous distribution of activity inside the lungs. However, it was not possible to take into account the dynamic feature, and often heterogeneous distribution between body organs and tissues of the activity. Still, the efficiency of the detection system depends on the distribution of the source of activity. The main purpose of the thesis work is to answer to the question: what is the influence of the biokinetics of the radionuclides on the in vivo counting? To answer it, it was necessary to deeply modify OEDIPE. This new development enabled to model the source of activity more realistically from the reference biokinetic models defined by the ICRP. The first part of the work consisted in developing the numerical tools needed to integrate the biokinetics in OEDIPE. Then, a methodology was developed to quantify its influence on the in vivo counting from the results of simulations. This method was carried out and validated on the model of the in vivo counting system of the LEDI. Finally, the

  1. Hybrid computational phantoms of the male and female newborn patient: NURBS-based whole-body models

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choonsik [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Lodwick, Daniel [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Hasenauer, Deanna [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Williams, Jonathan L [Department of Radiology, University of Florida, Gainesville, FL 32611 (United States); Lee, Choonik [MD Anderson Cancer Center-Orlando, Orlando, FL 32806 (United States); Bolch, Wesley E [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2007-07-21

    Anthropomorphic computational phantoms are computer models of the human body for use in the evaluation of dose distributions resulting from either internal or external radiation sources. Currently, two classes of computational phantoms have been developed and widely utilized for organ dose assessment: (1) stylized phantoms and (2) voxel phantoms which describe the human anatomy via mathematical surface equations or 3D voxel matrices, respectively. Although stylized phantoms based on mathematical equations can be very flexible in regard to making changes in organ position and geometrical shape, they are limited in their ability to fully capture the anatomic complexities of human internal anatomy. In turn, voxel phantoms have been developed through image-based segmentation and correspondingly provide much better anatomical realism in comparison to simpler stylized phantoms. However, they themselves are limited in defining organs presented in low contrast within either magnetic resonance or computed tomography images-the two major sources in voxel phantom construction. By definition, voxel phantoms are typically constructed via segmentation of transaxial images, and thus while fine anatomic features are seen in this viewing plane, slice-to-slice discontinuities become apparent in viewing the anatomy of voxel phantoms in the sagittal or coronal planes. This study introduces the concept of a hybrid computational newborn phantom that takes full advantage of the best features of both its stylized and voxel counterparts: flexibility in phantom alterations and anatomic realism. Non-uniform rational B-spline (NURBS) surfaces, a mathematical modeling tool traditionally applied to graphical animation studies, was adopted to replace the limited mathematical surface equations of stylized phantoms. A previously developed whole-body voxel phantom of the newborn female was utilized as a realistic anatomical framework for hybrid phantom construction. The construction of a hybrid

  2. Preliminary evaluation of specific absorbed fraction (SAF) in ICRP reference phantom conversion project

    Energy Technology Data Exchange (ETDEWEB)

    Thang, Nguyen Tat; Yeom, Yeon Soo; Han, Min Cheol; Jun, Wang Zhao; Kim, Han Sung; Kim, Seong Hoon; Kim, Chan Hyeong [Hanyang University, Seoul (Korea, Republic of)

    2014-11-15

    The ICRP reference phantoms, due to their low voxel resolutions, provide incorrect dose values for weakly penetrating radiations. To overcome the limitations, we are now converting the ICRPvoxel phantoms to polygonal surface models in order to develop the polygonal surface version of the ICRP reference phantoms. The ultimate goal of the conversion project is to develop a set of polygonal surface ICRP phantoms which provide correct dose values for weakly penetrating radiations while providing identical dose values with those of the ICRP reference phantoms for highly penetrating radiations. It was confirmed that indeed the current ICRP male polygonal phantom showed generally good agreement with the ICRP male voxel phantom following the objective of the ICRP phantom conversion project. However, relatively large discrepancies were found in the colon doses at 0.03 MeV. We believe that the discrepancies could be sufficiently reduced by adjusting the colon polygonal model to be more similar to the voxel model in the further study.

  3. New quantitative and multi-modal approach for in-vivo studies of small animals: coupling of the {beta}-microprobe with magnetic techniques and development of voxelized rat and mouse phantoms; Nouvelle approche multimodale et quantitative pour les etudes in vivo chez le petit animal: couplage de la {beta}-MicroProbe aux techniques magnetiques et developpement de fantomes de rat et de souris voxelises

    Energy Technology Data Exchange (ETDEWEB)

    Desbree, A

    2005-09-15

    For the last 15 years, animal models that mimic human disorders have become ubiquitous participants to understand biological mechanisms and human disorders and to evaluate new therapeutic approaches. The necessity to study these models in the course of time has stimulated the development of instruments dedicated to in vivo small animal studies. To further understand physiopathological processes, the current challenge is to couple simultaneously several of these methods. Given this context, the combination of the magnetic and radioactive techniques remains an exciting challenge since it is still limited by strict technical constraints. Therefore we propose to couple the magnetic techniques with the radiosensitive Beta-Microprobe, developed in the IPB group and which shown to be an elegant alternative to PET measurements. In this context, the thesis was dedicated to the study of the coupling feasibility from a physical point of view, by simulation and experimental characterizations. Then, the determination of a biological protocol was carried out on the basis of pharmacokinetic studies. The experiments have shown the possibility to use the probe for radioactive measurements under intense magnetic field simultaneously to anatomical images acquisitions. Simultaneously, we have sought to improve the quantification of the radioactive signal using a voxelized phantom of a rat brain. Finally, the emergence of transgenic models led us to reproduce pharmacokinetic studies for the mouse and to develop voxelized mouse phantoms. (author)

  4. Phantom Pain

    NARCIS (Netherlands)

    Wolff, Andre; Vanduynhoven, Eric; van Kleef, Maarten; Huygen, Frank; Pope, Jason E.; Mekhail, Nagy

    2011-01-01

    Phantom pain is pain caused by elimination or interruption of sensory nerve impulses by destroying or injuring the sensory nerve fibers after amputation or deafferentation. The reported incidence of phantom limb pain after trauma, injury or peripheral vascular diseases is 60% to 80%. Over half the p

  5. Voxel model in BNCT treatment planning: performance analysis and improvements

    Science.gov (United States)

    González, Sara J.; Carando, Daniel G.; Santa Cruz, Gustavo A.; Zamenhof, Robert G.

    2005-02-01

    In recent years, many efforts have been made to study the performance of treatment planning systems in deriving an accurate dosimetry of the complex radiation fields involved in boron neutron capture therapy (BNCT). The computational model of the patient's anatomy is one of the main factors involved in this subject. This work presents a detailed analysis of the performance of the 1 cm based voxel reconstruction approach. First, a new and improved material assignment algorithm implemented in NCTPlan treatment planning system for BNCT is described. Based on previous works, the performances of the 1 cm based voxel methods used in the MacNCTPlan and NCTPlan treatment planning systems are compared by standard simulation tests. In addition, the NCTPlan voxel model is benchmarked against in-phantom physical dosimetry of the RA-6 reactor of Argentina. This investigation shows the 1 cm resolution to be accurate enough for all reported tests, even in the extreme cases such as a parallelepiped phantom irradiated through one of its sharp edges. This accuracy can be degraded at very shallow depths in which, to improve the estimates, the anatomy images need to be positioned in a suitable way. Rules for this positioning are presented. The skin is considered one of the organs at risk in all BNCT treatments and, in the particular case of cutaneous melanoma of extremities, limits the delivered dose to the patient. Therefore, the performance of the voxel technique is deeply analysed in these shallow regions. A theoretical analysis is carried out to assess the distortion caused by homogenization and material percentage rounding processes. Then, a new strategy for the treatment of surface voxels is proposed and tested using two different irradiation problems. For a parallelepiped phantom perpendicularly irradiated with a 5 keV neutron source, the large thermal neutron fluence deviation present at shallow depths (from 54% at 0 mm depth to 5% at 4 mm depth) is reduced to 2% on average

  6. High resolution, MRI-based, segmented, computerized head phantom

    Energy Technology Data Exchange (ETDEWEB)

    Zubal, I.G.; Harrell, C.R.; Smith, E.O.; Smith, A.L.; Krischlunas, P. [Yale Univ., New Haven, CT (United States). Dept. of Diagnostic Radiology

    1999-01-01

    The authors have created a high-resolution software phantom of the human brain which is applicable to voxel-based radiation transport calculations yielding nuclear medicine simulated images and/or internal dose estimates. A software head phantom was created from 124 transverse MRI images of a healthy normal individual. The transverse T2 slices, recorded in a 256x256 matrix from a GE Signa 2 scanner, have isotropic voxel dimensions of 1.5 mm and were manually segmented by the clinical staff. Each voxel of the phantom contains one of 62 index numbers designating anatomical, neurological, and taxonomical structures. The result is stored as a 256x256x128 byte array. Internal volumes compare favorably to those described in the ICRP Reference Man. The computerized array represents a high resolution model of a typical human brain and serves as a voxel-based anthropomorphic head phantom suitable for computer-based modeling and simulation calculations. It offers an improved realism over previous mathematically described software brain phantoms, and creates a reference standard for comparing results of newly emerging voxel-based computations. Such voxel-based computations lead the way to developing diagnostic and dosimetry calculations which can utilize patient-specific diagnostic images. However, such individualized approaches lack fast, automatic segmentation schemes for routine use; therefore, the high resolution, typical head geometry gives the most realistic patient model currently available.

  7. Development of skeleton model for use in polygonal-mesh-type ICRP reference phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thang Tat; Yeom, Yeon Soo; Han, Min Cheol; Wang, Zhao Jun; Kim, Han Sung; Kim, Chan Hyeong [Dept.of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

    2015-04-15

    In order to overcome the limitations, we are currently developing the polygonal-mesh versions of the ICRP reference phantoms by converting the ICRP reference voxel phantoms to polygonal-mesh format. As a part of the ICRP reference phantom conversion project, the present study completed the conversion of skeleton, which is a very complex framework of the body, while addressing some critical problems of the skeleton of the ICRP reference voxel phantoms. The converted skeleton models were also evaluated by comparing dose values of RBM and endosteum with those of the ICRP reference voxel phantoms. As a part of the ICRP reference phantom conversion project, the present study successfully completed skeleton conversion of the ICRP reference adult male and female phantoms to polygonal-mesh format. A comprehensive study of dosimetric effects by the skeleton conversion will be performed in the future.

  8. Human phantom

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    This human phantom has been received by CERN on loan from the State Committee of the USSR for the Utilization of Atomic Energy. It is used by the Health Physics Group to study personel radiation doses near the accelerators.

  9. Phantom Pain

    Science.gov (United States)

    ... the pain, such as reading or listening to music. Stay physically active. Get your exercise by doing ... Sept. 16, 2014. Alviar MJM, et al. Pharmacologic interventions for treating phantom limb pain. Cochrane Database of ...

  10. A polygon-surface reference Korean male phantom (PSRK-Man) and its direct implementation in Geant4 Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Hyeong; Jeong, Jong Hwi [Department of Nuclear Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Bolch, Wesley E [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Cho, Kun-Woo [Korea Institute of Nuclear Safety, 19 Guseong-dong, Yuseong-gu, Daejeon 305-600 (Korea, Republic of); Hwang, Sung Bae, E-mail: chkim@hanyang.ac.kr [Department of Physical Therapy, Kyungbuk College, Hyucheon 2-dong, Yeongju-si, Gyeongbuk 750-712 (Korea, Republic of)

    2011-05-21

    Even though the hybrid phantom embodies both the anatomic reality of voxel phantoms and the deformability of stylized phantoms, it must be voxelized to be used in a Monte Carlo code for dose calculation or some imaging simulation, which incurs the inherent limitations of voxel phantoms. In the present study, a voxel phantom named VKH-Man (Visible Korean Human-Man), was converted to a polygon-surface phantom (PSRK-Man, Polygon-Surface Reference Korean-Man), which was then adjusted to the Reference Korean data. Subsequently, the PSRK-Man polygon phantom was directly, without any voxelization process, implemented in the Geant4 Monte Carlo code for dose calculations. The calculated dose values and computation time were then compared with those of HDRK-Man (High Definition Reference Korean-Man), a corresponding voxel phantom adjusted to the same Reference Korean data from the same VKH-Man voxel phantom. Our results showed that the calculated dose values of the PSRK-Man surface phantom agreed well with those of the HDRK-Man voxel phantom. The calculation speed for the PSRK-Man polygon phantom though was 70-150 times slower than that of the HDRK-Man voxel phantom; that speed, however, could be acceptable in some applications, in that direct use of the surface phantom PSRK-Man in Geant4 does not require a separate voxelization process. Computing speed can be enhanced, in future, either by optimizing the Monte Carlo transport kernel for the polygon surfaces or by using modern computing technologies such as grid computing and general-purpose computing on graphics processing units programming.

  11. Conversion of ICRP male reference phantom to polygon-surface phantom

    Science.gov (United States)

    Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong; Jeong, Jong Hwi

    2013-10-01

    The International Commission on Radiological Protection (ICRP) reference phantoms, developed based on computed tomography images of human bodies, provide much more realism of human anatomy than the previously used MIRD5 (Medical Internal Radiation Dose) mathematical phantoms. It has been, however, realized that the ICRP reference phantoms have some critical limitations showing a considerable amount of holes for the skin and wall organs mainly due to the nature of voxels of which the phantoms are made, especially due to their low voxel resolutions. To address this problem, we are planning to develop the polygon-surface version of ICRP reference phantoms by directly converting the ICRP reference phantoms (voxel phantoms) to polygon-surface phantoms. The objective of this preliminary study is to see if it is indeed possible to construct the high-quality polygon-surface phantoms based on the ICRP reference phantoms maintaining identical organ morphology and also to identify any potential issues, and technologies to address these issues, in advance. For this purpose, in the present study, the ICRP reference male phantom was roughly converted to a polygon-surface phantom. Then, the constructed phantom was implemented in Geant4, Monte Carlo particle transport code, for dose calculations, and the calculated dose values were compared with those of the original ICRP reference phantom to see how much the calculated dose values are sensitive to the accuracy of the conversion process. The results of the present study show that it is certainly possible to convert the ICRP reference phantoms to surface phantoms with enough accuracy. In spite of using relatively less resources (<2 man-months), we were able to construct the polygon-surface phantom with the organ masses perfectly matching the ICRP reference values. The analysis of the calculated dose values also implies that the dose values are indeed not very sensitive to the detailed morphology of the organ models in the phantom

  12. Age-dependent tissue-specific exposure of cell phone users

    Energy Technology Data Exchange (ETDEWEB)

    Christ, Andreas; Gosselin, Marie-Christine; Kuehn, Sven; Kuster, Niels [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr. 43, 8004 Zuerich (Switzerland); Christopoulou, Maria [National Technical University of Athens, School of Electrical and Computer Engineering, 9 Iroon Polytechniou Str., 15780 Athens (Greece)], E-mail: christ@itis.ethz.ch

    2010-04-07

    The peak spatial specific absorption rate (SAR) assessed with the standardized specific anthropometric mannequin head phantom has been shown to yield a conservative exposure estimate for both adults and children using mobile phones. There are, however, questions remaining concerning the impact of age-dependent dielectric tissue properties and age-dependent proportions of the skull, face and ear on the global and local absorption, in particular in the brain tissues. In this study, we compare the absorption in various parts of the cortex for different magnetic resonance imaging-based head phantoms of adults and children exposed to different models of mobile phones. The results show that the locally induced fields in children can be significantly higher (>3 dB) in subregions of the brain (cortex, hippocampus and hypothalamus) and the eye due to the closer proximity of the phone to these tissues. The increase is even larger for bone marrow (>10 dB) as a result of its significantly high conductivity. Tissues such as the pineal gland show no increase since their distances to the phone are not a function of age. This study, however, confirms previous findings saying that there are no age-dependent changes of the peak spatial SAR when averaged over the entire head.

  13. Calculations of internal and external radiation exposure based on voxel models. Final report; Berechnungen der internen und externen Strahlenexposition auf Grundlage von Voxel-Modellen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Zankl, M. [Helmholtz Zentrum Muenchen - Deutsches Forschungszentrum fuer Gesundheit und Umwelt, Muenchen (Germany). Inst fuer Strahlenschutz; Becker, J.; Petoussi-Henss, N.; Schlattl, H.

    2012-02-15

    Dose estimations of internal and external radiation exposure were based so far on mathematical phantoms with rather simple geometrical descriptions of the human body and teh organs. Recently the mathematical phantoms are replaced by more realistic voxel models that allow a more realistic dose estimation for professional radiation exposed personnel, individuals and patients. The projects is aimed to calculate organ doses for exposure to environmental radiation, organ doses for patients during computed tomography and to develop a voxel model for pregnant (24th week of pregnancy) woman for the estimation of radiation doses for the unborn child.

  14. Age-dependent xylogenesis in timberline conifers.

    Science.gov (United States)

    Rossi, Sergio; Deslauriers, Annie; Anfodillo, Tommaso; Carrer, Marco

    2008-01-01

    Neither anatomical change nor physiological abnormalities have been observed in the cambia of older trees. However, different sensitivity and period of significant responses to climate suggest the existence of some age-related change in the patterns of cambial activity and/or wood cell formation. Here, weekly cambial activity and timing and duration of xylem cell enlargement and wall thickening were compared in adult (50-80 yr) and old (200-350 yr) trees of Larix decidua, Pinus cembra and Picea abies at the Alpine timberline during 2004 and 2005. Timings and durations of xylogenesis differed between adult and old trees, with 2-3 wk shorter cambial activity found in the latter. The delayed onset of cambium division and lower cell production in old trees, with respect to adult trees, led to reductions of 15-20% in the overall duration of xylem differentiation. These results demonstrate that cambial dynamics change during the tree lifespan and that the time window of tree-ring production shortens with age. Variations in the period of xylem growth may be the cause of age-dependent responses to climate. The observed shorter xylogenesis in older plants at the Alpine timberline could be related to a size effect and not just to age per se.

  15. The UF family of reference hybrid phantoms for computational radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choonsik [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, MD 20852 (United States); Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Williams, Jonathan L [Department of Radiology, University of Florida, Gainesville, FL 32611 (United States); Bolch, Wesley E [Departments of Nuclear and Radiological and Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States)], E-mail: wbolch@ufl.edu

    2010-01-21

    Computational human phantoms are computer models used to obtain dose distributions within the human body exposed to internal or external radiation sources. In addition, they are increasingly used to develop detector efficiencies for in vivo whole-body counters. Two classes of computational human phantoms have been widely utilized for dosimetry calculation: stylized and voxel phantoms that describe human anatomy through mathematical surface equations and 3D voxel matrices, respectively. Stylized phantoms are flexible in that changes to organ position and shape are possible given avoidance of region overlap, while voxel phantoms are typically fixed to a given patient anatomy, yet can be proportionally scaled to match individuals of larger or smaller stature, but of equivalent organ anatomy. Voxel phantoms provide much better anatomical realism as compared to stylized phantoms which are intrinsically limited by mathematical surface equations. To address the drawbacks of these phantoms, hybrid phantoms based on non-uniform rational B-spline (NURBS) surfaces have been introduced wherein anthropomorphic flexibility and anatomic realism are both preserved. Researchers at the University of Florida have introduced a series of hybrid phantoms representing the ICRP Publication 89 reference newborn, 15 year, and adult male and female. In this study, six additional phantoms are added to the UF family of hybrid phantoms-those of the reference 1 year, 5 year and 10 year child. Head and torso CT images of patients whose ages were close to the targeted ages were obtained under approved protocols. Major organs and tissues were segmented from these images using an image processing software, 3D-DOCTOR(TM). NURBS and polygon mesh surfaces were then used to model individual organs and tissues after importing the segmented organ models to the 3D NURBS modeling software, Rhinoceros(TM). The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference

  16. Effect of voxel size when calculating patient specific radionuclide dosimetry estimates using direct Monte Carlo simulation.

    Science.gov (United States)

    Hickson, Kevin J; O'Keefe, Graeme J

    2014-09-01

    The scalable XCAT voxelised phantom was used with the GATE Monte Carlo toolkit to investigate the effect of voxel size on dosimetry estimates of internally distributed radionuclide calculated using direct Monte Carlo simulation. A uniformly distributed Fluorine-18 source was simulated in the Kidneys of the XCAT phantom with the organ self dose (kidney ← kidney) and organ cross dose (liver ← kidney) being calculated for a number of organ and voxel sizes. Patient specific dose factors (DF) from a clinically acquired FDG PET/CT study have also been calculated for kidney self dose and liver ← kidney cross dose. Using the XCAT phantom it was found that significantly small voxel sizes are required to achieve accurate calculation of organ self dose. It has also been used to show that a voxel size of 2 mm or less is suitable for accurate calculations of organ cross dose. To compensate for insufficient voxel sampling a correction factor is proposed. This correction factor is applied to the patient specific dose factors calculated with the native voxel size of the PET/CT study.

  17. Improvement of skeleton conversion in ICRP reference phantom conversion project

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of); Kim, Seong Hoon [Dept. of Radiation Oncology, College of Medicine, Hanyang University, Seoul (Korea, Republic of)

    2014-11-15

    In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future.

  18. Evaluation of dose conversion coefficients for an eight-year-old Iranian male phantom undergoing computed tomography.

    Science.gov (United States)

    Akhlaghi, Parisa; Hakimabad, Hashem Miri; Motavalli, Laleh Rafat

    2015-11-01

    In order to construct a library of Iranian pediatric voxel phantoms for radiological protection and dosimetry applications, an Iranian eight-year-old phantom was constructed from a series of CT images. Organ and effective dose conversion coefficients to this phantom were calculated for head, chest, abdominopelvis and chest-abdomen-pelvis scans at tube voltages of 80, 100 and 120 kVp. To validate the results, the organ and effective dose conversion coefficients obtained were compared with those of the University of Florida eight-year-old voxel female phantom as a function of examination type and anatomical scan area. For a detailed study, depth distributions of organs together with the thickness of surrounding tissues located in the beam path, which are shielding the internal organs, were determined for these two voxel phantoms. The relation between the anatomical differences and the level of delivered dose was investigated and the discrepancies among the results justified.

  19. Development of prostate voxel models for brachytherapy treatment

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Adriano M.; Reis, Lucas P.; Grynberg, Suely E., E-mail: amsantos@cdtn.b [Center for Development of Nuclear Technology (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    The tools developed recently in the areas of computer graphics and animation movies to computer games allow the creation of new voxel anthropomorphic phantoms with better resolution and thus, more anatomical details. These phantoms can be used in nuclear applications, especially in radiation protection for estimating doses in cases of occupational or accidental radioactive incidents, and in medical and biological applications. For dose estimates, the phantoms are coupled to a Monte Carlo code, which will be responsible for the transport of radiation in this environment. This study aimed to develop a computational tool to estimate the isodose curves in the prostate after brachytherapy seed implants. For this, we have created a model called FANTPROST in the shape of a 48 mm side cube, with a standard prostate inserted in the center of this cube with different distributions of brachytherapy seeds in this volume. The prostate, according to this model, was obtained from the phantom voxels MASH2 developed by Numerical Dosimetry Group, Department of Nuclear Energy - Federal University of Pernambuco. The modeling of the seeds, added to FANTPROST, was done through the use of geometric information of Iodine-125 Amersham 6711 commercial seed. The simulations were performed by the code MCNP5 for spatial distributions containing different amounts of seeds within the FANTPROST. The obtained curves allowed an estimation of the behavior of the maximum dose that decreases with distance, showing that this tool can be used for a more accurate analysis of the effects produced by the presence of such seeds in the prostate and its vicinity. (author)

  20. Development of skeletal system for mesh-type ICRP reference adult phantoms

    Science.gov (United States)

    Yeom, Yeon Soo; Wang, Zhao Jun; Tat Nguyen, Thang; Kim, Han Sung; Choi, Chansoo; Han, Min Cheol; Kim, Chan Hyeong; Lee, Jai Ki; Chung, Beom Sun; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E.; Lee, Choonsik

    2016-10-01

    The reference adult computational phantoms of the international commission on radiological protection (ICRP) described in Publication 110 are voxel-type computational phantoms based on whole-body computed tomography (CT) images of adult male and female patients. The voxel resolutions of these phantoms are in the order of a few millimeters and smaller tissues such as the eye lens, the skin, and the walls of some organs cannot be properly defined in the phantoms, resulting in limitations in dose coefficient calculations for weakly penetrating radiations. In order to address the limitations of the ICRP-110 phantoms, an ICRP Task Group has been recently formulated and the voxel phantoms are now being converted to a high-quality mesh format. As a part of the conversion project, in the present study, the skeleton models, one of the most important and complex organs of the body, were constructed. The constructed skeleton models were then tested by calculating red bone marrow (RBM) and endosteum dose coefficients (DCs) for broad parallel beams of photons and electrons and comparing the calculated values with those of the original ICRP-110 phantoms. The results show that for the photon exposures, there is a generally good agreement in the DCs between the mesh-type phantoms and the original voxel-type ICRP-110 phantoms; that is, the dose discrepancies were less than 7% in all cases except for the 0.03 MeV cases, for which the maximum difference was 14%. On the other hand, for the electron exposures (⩽4 MeV), the DCs of the mesh-type phantoms deviate from those of the ICRP-110 phantoms by up to ~1600 times at 0.03 MeV, which is indeed due to the improvement of the skeletal anatomy of the developed skeleton mesh models.

  1. On the need to revise the arm structure in stylized anthropomorphic phantoms in lateral photon irradiation geometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choonsik [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Lee, Choonik [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Lee, Jai-Ki [Department of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

    2006-11-07

    Distributions of radiation absorbed dose within human anatomy have been estimated through Monte Carlo radiation transport techniques implemented for two different classes of computational anthropomorphic phantoms: (1) mathematical equation-based stylized phantoms and (2) tomographic image-based voxel phantoms. Voxel phantoms constructed from tomographic images of real human anatomy have been actively developed since the late 1980s to overcome the anatomical approximations necessary with stylized phantoms, which themselves have been utilized since the mid 1960s. However, revisions of stylized phantoms have also been pursued in parallel to the development of voxel phantoms since voxel phantoms (1) are initially restricted to the individual-specific anatomy of the person originally imaged, (2) must be restructured on an organ-by-organ basis to conform to reference individual anatomy and (3) cannot easily represent very fine anatomical structures and tissue layers that are thinner than the voxel dimensions of the overall phantom. Although efforts have been made to improve the anatomic realism of stylized phantoms, most of these efforts have been limited to attempts to alter internal organ structures. Aside from the internal organs, the exterior shapes, and especially the arm structures, of stylized phantoms are also far from realistic descriptions of human anatomy, and may cause dosimetry errors in the calculation of organ-absorbed doses for external irradiation scenarios. The present study was intended to highlight the need to revise the existing arm structure within stylized phantoms by comparing organ doses of stylized adult phantoms with those from three adult voxel phantoms in the lateral photon irradiation geometry. The representative stylized phantom, the adult phantom of the Oak Ridge National Laboratory (ORNL) series and two adult male voxel phantoms, KTMAN-2 and VOXTISS8, were employed for Monte Carlo dose calculation, and data from another voxel phantom, VIP

  2. The acoustical significance of age-dependent ear elongation

    DEFF Research Database (Denmark)

    Christensen, Flemming

    2015-01-01

    Elderly people, especially some old men, appear to have very large ears. This paper presents an investigation on the acoustic significance of the age dependent ear elongation. HRTFs and ear lengths were measured for two groups of young and old people. The older groups had larger ears on average......, corresponding to what is reported in the literature. For female ears, virtually no acoustical effect was found. For male ears directional dependent effects in the range up to 5 dB on average was found for certain directions and frequencies. Implications on age dependent hearing loss (presbycusis...

  3. The acoustical significance of age-dependent ear elongation

    DEFF Research Database (Denmark)

    Christensen, Flemming

    2015-01-01

    Elderly people, especially some old men, appear to have very large ears. This paper presents an investigation on the acoustic significance of the age dependent ear elongation. HRTFs and ear lengths were measured for two groups of young and old people. The older groups had larger ears on average...

  4. Automatic Calibration Method of Voxel Size for Cone-beam 3D-CT Scanning System

    CERN Document Server

    Yang, Min; Liu, Yipeng; Men, Fanyong; Li, Xingdong; Liu, Wenli; Wei, Dongbo

    2013-01-01

    For cone-beam three-dimensional computed tomography (3D-CT) scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary table along X-ray direction. In order to realize the automatic calibration of the voxel size, a new easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least square fitting. Through these interpolation values, a linear equation is obtained, which reflects the relationship between the rotary table displacement distance from its nominal zero position and the voxel size. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system, and when the rotary table is moving along X-ray direction, the accurate value of the voxel size is dynamically expo...

  5. Differential age-dependent import regulation by signal peptides.

    Directory of Open Access Journals (Sweden)

    Yi-Shan Teng

    Full Text Available Gene-specific, age-dependent regulations are common at the transcriptional and translational levels, while protein transport into organelles is generally thought to be constitutive. Here we report a new level of differential age-dependent regulation and show that chloroplast proteins are divided into three age-selective groups: group I proteins have a higher import efficiency into younger chloroplasts, import of group II proteins is nearly independent of chloroplast age, and group III proteins are preferentially imported into older chloroplasts. The age-selective signal is located within the transit peptide of each protein. A group III protein with its transit peptide replaced by a group I transit peptide failed to complement its own mutation. Two consecutive positive charges define the necessary motif in group III signals for older chloroplast preference. We further show that different members of a gene family often belong to different age-selective groups because of sequence differences in their transit peptides. These results indicate that organelle-targeting signal peptides are part of cells' differential age-dependent regulation networks. The sequence diversity of some organelle-targeting peptides is not a result of the lack of selection pressure but has evolved to mediate regulation.

  6. Managing phantom pain.

    Science.gov (United States)

    Manchikanti, Laxmaiah; Singh, Vijay

    2004-07-01

    Since the first medical description of post-amputation phenomena reported by Ambrose Paré, persistent phantom pain syndromes have been well recognized. However, they continue to be difficult to manage. The three most commonly utilized terms include phantom sensation, phantom pain, and stump pain. Phantom limb sensation is an almost universal occurrence at some time during the first month following surgery. However, most phantom sensations generally resolve after two to three years without treatment, except in the cases where phantom pain develops. The incidence of phantom limb pain has been reported to vary from 0% to 88%. The incidence of phantom limb pain increases with more proximal amputations. Even though phantom pain may diminish with time and eventually fade away, it has been shown that even two years after amputation, the incidence is almost the same as at onset. Consequently, almost 60% of patients continue to have phantom limb pain after one year. In addition, phantom limb pain may also be associated with multiple pain problems in other areas of the body. The third symptom, stump pain, is located in the stump itself. The etiology and pathophysiological mechanisms of phantom pain are not clearly defined. However, both peripheral and central neural mechanisms have been described, along with superimposed psychological mechanisms. Literature describing the management of phantom limb pain or stump pain is in its infancy. While numerous treatments have been described, there is little clinical evidence supporting drug therapy, psychological therapy, interventional techniques or surgery. This review will describe epidemiology, etiology and pathophysiological mechanisms, risk factors, and treatment modalities. The review also examines the effectiveness of various described modalities for prevention, as well as management of established phantom pain syndromes.

  7. Experimental and computational development of a natural breast phantom for dosimetry studies

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Luciana B.; Campos, Tarcisio P.R., E-mail: lucibn19@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2013-07-01

    This paper describes the experimental and computational development of a natural breast phantom, anthropomorphic and anthropometric for studies in dosimetry of brachytherapy and teletherapy of breast. The natural breast phantom developed corresponding to fibroadipose breasts of women aged 30 to 50 years, presenting radiographically medium density. The experimental breast phantom was constituted of three tissue-equivalents (TE's): glandular TE, adipose TE and skin TE. These TE's were developed according to chemical composition of human breast and present radiological response to exposure. Completed the construction of experimental breast phantom this was mounted on a thorax phantom previously developed by the research group NRI/UFMG. Then the computational breast phantom was constructed by performing a computed tomography (CT) by axial slices of the chest phantom. Through the images generated by CT a computational model of voxels of the thorax phantom was developed by SISCODES computational program, being the computational breast phantom represented by the same TE's of the experimental breast phantom. The images generated by CT allowed evaluating the radiological equivalence of the tissues. The breast phantom is being used in studies of experimental dosimetry both in brachytherapy as in teletherapy of breast. Dosimetry studies by MCNP-5 code using the computational model of the phantom breast are in progress. (author)

  8. New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications.

    Science.gov (United States)

    Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

    2016-05-01

    Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

  9. New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications

    Science.gov (United States)

    Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

    2016-05-01

    Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

  10. Anomalous scaling in an age-dependent branching model.

    Science.gov (United States)

    Keller-Schmidt, Stephanie; Tuğrul, Murat; Eguíluz, Víctor M; Hernández-García, Emilio; Klemm, Konstantin

    2015-02-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ(-α). Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)(2). This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus providing a theoretical support for age-dependent speciation and associating it to the occurrence of a critical point.

  11. Rotating and translating anthropomorphic head voxel models to establish an horizontal Frankfort plane for dental CBCT Monte Carlo simulations: a dose comparison study

    Science.gov (United States)

    Stratis, A.; Zhang, G.; Jacobs, R.; Bogaerts, R.; Bosmans, H.

    2016-12-01

    In order to carry out Monte Carlo (MC) dosimetry studies, voxel phantoms, modeling human anatomy, and organ-based segmentation of CT image data sets are applied to simulation frameworks. The resulting voxel phantoms preserve patient CT acquisition geometry; in the case of head voxel models built upon head CT images, the head support with which CT scanners are equipped introduces an inclination to the head, and hence to the head voxel model. In dental cone beam CT (CBCT) imaging, patients are always positioned in such a way that the Frankfort line is horizontal, implying that there is no head inclination. The orientation of the head is important, as it influences the distance of critical radiosensitive organs like the thyroid and the esophagus from the x-ray tube. This work aims to propose a procedure to adjust head voxel phantom orientation, and to investigate the impact of head inclination on organ doses in dental CBCT MC dosimetry studies. The female adult ICRP, and three in-house-built paediatric voxel phantoms were in this study. An EGSnrc MC framework was employed to simulate two commonly used protocols; a Morita Accuitomo 170 dental CBCT scanner (FOVs: 60  ×  60 mm2 and 80  ×  80 mm2, standard resolution), and a 3D Teeth protocol (FOV: 100  ×  90 mm2) in a Planmeca Promax 3D MAX scanner. Result analysis revealed large absorbed organ dose differences in radiosensitive organs between the original and the geometrically corrected voxel models of this study, ranging from  -45.6% to 39.3%. Therefore, accurate dental CBCT MC dose calculations require geometrical adjustments to be applied to head voxel models.

  12. Parthanatos Mediates AIMP2 Activated Age Dependent Dopaminergic Neuronal Loss

    Science.gov (United States)

    Lee, Yunjong; Karuppagounder, Senthilkumar S.; Shin, Joo-Ho; Lee, Yun-Il; Ko, Han Seok; Swing, Debbie; Jiang, Haisong; Kang, Sung-Ung; Lee, Byoung Dae; Kang, Ho Chul; Kim, Donghoon; Tessarollo, Lino; Dawson, Valina L.; Dawson, Ted M.

    2013-01-01

    The defining pathogenic feature of Parkinson’s disease is the age dependent loss of dopaminergic neurons. Mutations and inactivation of parkin, an ubiquitin E3 ligase, cause Parkinson’s disease through accumulation of pathogenic substrates. Here we show that transgenic overexpression of the parkin substrate, aminoacyl-tRNA synthetase complex interacting multifunctional protein-2 (AIMP2) leads to a selective, age-dependent progressive loss of dopaminergic neurons via activation of poly(ADP-ribose) polymerase-1 (PARP1). AIMP2 accumulation in vitro and in vivo results in PARP1 overactivation and dopaminergic cell toxicity via direct association of these proteins in the nucleus providing a new path to PARP1 activation other than DNA damage. Inhibition of PARP1 through gene deletion or drug inhibition reverses behavioral deficits and protects in vivo against dopamine neuron death in AIMP2 transgenic mice. These data indicate that brain permeable PARP inhibitors could be effective in delaying or preventing disease progression in Parkinson’s disease. PMID:23974709

  13. Role of Mitochondrial Complex IV in Age-Dependent Obesity

    Directory of Open Access Journals (Sweden)

    Ines Soro-Arnaiz

    2016-09-01

    Full Text Available Aging is associated with progressive white adipose tissue (WAT enlargement initiated early in life, but the molecular mechanisms involved remain unknown. Here we show that mitochondrial complex IV (CIV activity and assembly are already repressed in white adipocytes of middle-aged mice and involve a HIF1A-dependent decline of essential CIV components such as COX5B. At the molecular level, HIF1A binds to the Cox5b proximal promoter and represses its expression. Silencing of Cox5b decreased fatty acid oxidation and promoted intracellular lipid accumulation. Moreover, local in vivo Cox5b silencing in WAT of young mice increased the size of adipocytes, whereas restoration of COX5B expression in aging mice counteracted adipocyte enlargement. An age-dependent reduction in COX5B gene expression was also found in human visceral adipose tissue. Collectively, our findings establish a pivotal role for CIV dysfunction in progressive white adipocyte enlargement during aging, which can be restored to alleviate age-dependent WAT expansion.

  14. Age-dependent social learning in a lizard.

    Science.gov (United States)

    Noble, Daniel W A; Byrne, Richard W; Whiting, Martin J

    2014-07-01

    Evidence of social learning, whereby the actions of an animal facilitate the acquisition of new information by another, is taxonomically biased towards mammals, especially primates, and birds. However, social learning need not be limited to group-living animals because species with less interaction can still benefit from learning about potential predators, food sources, rivals and mates. We trained male skinks (Eulamprus quoyii), a mostly solitary lizard from eastern Australia, in a two-step foraging task. Lizards belonging to 'young' and 'old' age classes were presented with a novel instrumental task (displacing a lid) and an association task (reward under blue lid). We did not find evidence for age-dependent learning of the instrumental task; however, young males in the presence of a demonstrator learnt the association task faster than young males without a demonstrator, whereas old males in both treatments had similar success rates. We present the first evidence of age-dependent social learning in a lizard and suggest that the use of social information for learning may be more widespread than previously believed.

  15. Development of polygonal-surface version of ICRP reference phantoms: Lymphatic node modeling

    Energy Technology Data Exchange (ETDEWEB)

    Thang, Ngyen Tat; Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong [Hanyang University, Seoul (Korea, Republic of)

    2014-04-15

    Among radiosensitive organs/tissues considered in ICRP Publication 103, lymphatic nodes are many small size tissues and widely distributed in the ICRP reference phantoms. It is difficult to directly convert lymphatic nodes of ICRP reference voxel phantoms to polygonal surfaces. Furthermore, in the ICRP reference phantoms lymphatic nodes were manually drawn only in six lymphatic node regions and the reference number of lymphatic nodes reported in ICRP Publication 89 was not considered. To address aforementioned limitations, the present study developed a new lymphatic node modeling method for the polygonal-surface version of ICRP reference phantoms. By using the developed method, lymphatic nodes were modelled in the preliminary version of ICRP male polygonal-surface phantom. Then, lymphatic node dose values were calculated and compared with those of the ICRP reference male voxel phantom to validate the developed modeling method. The present study developed the new lymphatic node modeling method and successfully modeled lymphatic nodes in the preliminary version of the ICRP male polygonal-surface phantom. From the results, it was demonstrated that the developed modeling method can be used to model lymphatic nodes in polygonal-surface version of ICRP reference phantoms.

  16. Phantom cosmologies and fermions

    CERN Document Server

    Chimento, Luis P; Forte, Monica; Kremer, Gilberto M

    2007-01-01

    Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the "phantomization" process exhibits a new class of possible accelerated regimes.

  17. 21. Phantom pain.

    NARCIS (Netherlands)

    Wolff, A.P.; Vanduynhoven, E.; Kleef, M. van; Huygen, F.; Pope, J.E.; Mekhail, N.

    2011-01-01

    Phantom pain is pain caused by elimination or interruption of sensory nerve impulses by destroying or injuring the sensory nerve fibers after amputation or deafferentation. The reported incidence of phantom limb pain after trauma, injury or peripheral vascular diseases is 60% to 80%. Over half the p

  18. Age-dependent dose coefficients for tritium in Asian populations

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, A

    1999-10-01

    The International Commission on Radiological Protection (ICRP) Publications 56 (1989) and 67 (1993) have prescribed the biokinetic models and age-dependent dose coefficients for tritiated water and organically bound tritium. The dose coefficients are computed from values selected to specify the anatomical, morphological and physiological characteristics of a three-month-old, one-year-old, five-year-old, 10-year-old, 15-year-old and adult (Reference Man) Caucasian living in North America and Western Europe. However, values for Reference Man and other age groups are not directly applicable to Asians, because of differences in race, custom, dietary habits and climatic conditions. An Asian Man model, including five age groups, has been proposed by Tanaka and Kawamura (1996, 1998) for use in internal dosimetry. The basic concept of the ICRP Reference Man and the system describing body composition in ICRP Publication 23 (1975) were used. Reference values for Asians were given for the body weight and height, the mass of soft tissue, the mass of body water and the daily fluid balance, and are used to compute the dose coefficients for tritium. The age-dependent dose coefficients for Asians for tritiated water intakes are smaller by 20 to 30% of the currently prescribed values (Trivedi, 1998). The reduction in the dose coefficient values is caused by the increased daily fluid balance among Asians. The dose coefficient for tritiated water is 1.4 x 10{sup -11} Sv Bq{sup -1} for Asian Man compared to 2.0 x 10{sup -11} Sv Bq{sup -1} for Reference Man. The dose coefficients for organically bound tritium are only marginally different from those of the ICRP values. The dose coefficient for organically bound tritium for Asian Man is 4.0 x 10{sup -11} Sv Bq{sup -11} compared to 4.6 x 10{sup -11} Sv Bq{sup -1} for Reference Man. (author)

  19. Peripheral surgical wounding and age-dependent neuroinflammation in mice.

    Directory of Open Access Journals (Sweden)

    Zhipeng Xu

    Full Text Available Post-operative cognitive dysfunction is associated with morbidity and mortality. However, its neuropathogenesis remains largely to be determined. Neuroinflammation and accumulation of β-amyloid (Aβ have been reported to contribute to cognitive dysfunction in humans and cognitive impairment in animals. Our recent studies have established a pre-clinical model in mice, and have found that the peripheral surgical wounding without the influence of general anesthesia induces an age-dependent Aβ accumulation and cognitive impairment in mice. We therefore set out to assess the effects of peripheral surgical wounding, in the absence of general anesthesia, on neuroinflammation in mice with different ages. Abdominal surgery under local anesthesia was established in 9 and 18 month-old mice. The levels of tumor necrosis factor-α (TNF-α, interleukin-6 (IL-6, Iba1 positive cells (the marker of microglia activation, CD33, and cognitive function in mice were determined. The peripheral surgical wounding increased the levels of TNF-α, IL-6, and Iba1 positive cells in the hippocampus of both 9 and 18 month-old mice, and age potentiated these effects. The peripheral surgical wounding increased the levels of CD33 in the hippocampus of 18, but not 9, month-old mice. Finally, anti-inflammatory drug ibuprofen ameliorated the peripheral surgical wounding-induced cognitive impairment in 18 month-old mice. These data suggested that the peripheral surgical wounding could induce an age-dependent neuroinflammation and elevation of CD33 levels in the hippocampus of mice, which could lead to cognitive impairment in aged mice. Pending further studies, anti-inflammatory therapies may reduce the risk of postoperative cognitive dysfunction in elderly patients.

  20. Motion as a perturbation: Measurement-guided dose estimates to moving patient voxels during modulated arc deliveries

    Energy Technology Data Exchange (ETDEWEB)

    Feygelman, Vladimir; Zhang, Geoffrey; Hunt, Dylan; Opp, Daniel [Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Stambaugh, Cassandra [Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Wolf, Theresa K. [Live Oak Technologies LLC, Kirkwood, Missouri 63122 (United States); Nelms, Benjamin E. [Canis Lupus LLC, Merrimac, Wisconsin 53561 (United States)

    2013-02-15

    Purpose: To present a framework for measurement-guided VMAT dose reconstruction to moving patient voxels from a known motion kernel and the static phantom data, and to validate this perturbation-based approach with the proof-of-principle experiments. Methods: As described previously, the VMAT 3D dose to a static patient can be estimated by applying a phantom measurement-guided perturbation to the treatment planning system (TPS)-calculated dose grid. The fraction dose to any voxel in the presence of motion, assuming the motion kernel is known, can be derived in a similar fashion by applying a measurement-guided motion perturbation. The dose to the diodes in a helical phantom is recorded at 50 ms intervals and is transformed into a series of time-resolved high-density volumetric dose grids. A moving voxel is propagated through this 4D dose space and the fraction dose to that voxel in the phantom is accumulated. The ratio of this motion-perturbed, reconstructed dose to the TPS dose in the phantom serves as a perturbation factor, applied to the TPS fraction dose to the similarly situated voxel in the patient. This approach was validated by the ion chamber and film measurements on four phantoms of different shape and structure: homogeneous and inhomogeneous cylinders, a homogeneous cube, and an anthropomorphic thoracic phantom. A 2D motion stage was used to simulate the motion. The stage position was synchronized with the beam start time with the respiratory gating simulator. The motion patterns were designed such that the motion speed was in the upper range of the expected tumor motion (1-1.4 cm/s) and the range exceeded the normally observed limits (up to 5.7 cm). The conformal arc plans for X or Y motion (in the IEC 61217 coordinate system) consisted of manually created narrow (3 cm) rectangular strips moving in-phase (tracking) or phase-shifted by 90 Degree-Sign (crossing) with respect to the phantom motion. The XY motion was tested with the computer-derived VMAT

  1. Calibration of a radioactive ink-based stack phantom and its applications in nuclear medicine.

    Science.gov (United States)

    El-Ali, H; Ljungberg, M; Strand, S-E; Palmer, J; Malmgren, L; Nilsson, J

    2003-04-01

    This paper describes a stack phantom useful for imaging complex activity distributions. It is based on images printed with radioactive ink using a commercial ink-jet printer. The application for the phantom is in the evaluation of planar and SPECT scintillation camera images and for validation of Monte Carlo simulated images. The accuracy in generating the activity distributions on paper sheets is especially important. Here we describe the calibration procedure for the ink-jet printer. The goal of the printer calibration is to find the relationship between the digital image count (voxel grey level) and its corresponding activity on the paper sheets (radioactivity). The relationship between the voxel grey level and the radioactivity on the paper sheets (measured by scanning technique and well counter) was found to be logarithmic, and a 3rd degree polynomial was found to fit the relationship. The distribution of radioactivity in the ink cartridge was investigated by pinhole SPECT. The distribution of (99m)Tc solution was found to be homogeneous in the ink solution. Experimental studies were done directly on Monte Carlo simulated heart images from the NCAT phantom. The result showed that the simulated images are similar to the images measured using the ink-jet technique. This stack phantom could be a promising solution with an advantage that the exact geometry generated in Monte Carlo could be imitated in the phantom. The phantom is a very flexible device and clearly much more versatile than conventional phantoms which have a fixed geometry and spatial limitation.

  2. Age-dependent branching processes in random environments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We consider an age-dependent branching process in random environments. The environments are represented by a stationary and ergodic sequence ξ = (ξ0,ξ1,...) of random variables. Given an environment ξ, the process is a non-homogenous Galton-Watson process, whose particles in n-th generation have a life length distribution G(ξn) on R+, and reproduce independently new particles according to a probability law p(ξn) on N. Let Z(t) be the number of particles alive at time t. We first find a characterization of the conditional probability generating function of Z(t) (given the environment ξ) via a functional equation, and obtain a criterion for almost certain extinction of the process by comparing it with an embedded Galton-Watson process. We then get expressions of the conditional mean EξZ(t) and the global mean EZ(t), and show their exponential growth rates by studying a renewal equation in random environments.

  3. Age-dependent increase in green autofluorescence of blood erythrocytes

    Indian Academy of Sciences (India)

    Sanjay Khandelwal; Rajiv K Saxena

    2007-12-01

    Green auto-fluorescence (GAF) of different age groups of mouse blood erythrocytes was determined by using a double in vivo biotinylation (DIB) technique that enables delineation of circulating erythrocytes of different age groups. A significant increase in GAF was seen for erythrocytes of old age group (age in circulation > 40 days) as compared to young erythrocytes (age < 15 days). Erythrocytes are removed from blood circulation by macrophages in the reticulo-endothelial system and depletion of macrophages results in an increased proportion of aged erythrocytes in the blood. When mice were depleted of macrophages for 7 days by administration of clodronate loaded liposomes, the overall GAF of erythrocytes increased significantly and this increase could be ascribed to an increase in GAF of the oldest population of erythrocytes. Using the DIB technique, the GAF of a cohort of blood erythrocyte generated during a 5 day window was tracked in vivo. GAF of the defined cohort of erythrocytes remained low till 40 days of age in circulation and then increased steeply till the end of the life span of erythrocytes. Taken together our results provide evidence for an age dependent increase in the GAF of blood erythrocytes that is accentuated by depletion of macrophages. Kinetics of changes in GAF of circulating erythrocytes with age has also been defined.

  4. Age-dependent branching processes in random environments

    Institute of Scientific and Technical Information of China (English)

    LI YingQiu; LIU QuanSheng

    2008-01-01

    We consider an age-dependent branching process in random environments.The environments are represented by a stationary and ergodic sequence ξ = (ξ0,ξ1,...) of random variables.Given an environment ξ,the process is a non-homogenous Galton-Watson process,whose particles in n-th generation have a life length distribution G(ξn) on R+,and reproduce independently new particles according to a probability law p(ξn) on N.Let Z(t) be the number of particles alive at time t.We first find a characterization of the conditional probability generating function of Z(t) (given the environment ξ) via a functional equation,and obtain a criterion for almost certain extinction of the process by comparing it with an embedded Galton-Watson process.We then get expressions of the conditional mean EξZ(t) and the global mean EZ(t),and show their exponential growth rates by studying a renewal equation in random environments.

  5. Age-dependent increase in green autofluorescence of blood erythrocytes

    Indian Academy of Sciences (India)

    Sanjay Khandelwal; Rajiv K Saxena

    2007-09-01

    Green auto-fluorescence (GAF) of different age groups of mouse blood erythrocytes was determined by using a double in vivo biotinylation (DIB) technique that enables delineation of circulating erythrocytes of different age groups. A significant increase in GAF was seen for erythrocytes of old age group (age in circulation > 40 days) as compared to young erythrocytes (age < 15 days). Erythrocytes are removed from blood circulation by macrophages in the reticulo-endothelial system and depletion of macrophages results in an increased proportion of aged erythrocytes in the blood. When mice were depleted of macrophages for 7 days by administration of clodronate loaded liposomes, the overall GAF of erythrocytes increased significantly and this increase could be ascribed to an increase in GAF of the oldest population of erythrocytes. Using the DIB technique, the GAF of a cohort of blood erythrocyte generated during a 5 day window was tracked in vivo. GAF of the defined cohort of erythrocytes remained low till 40 days of age in circulation and then increased steeply till the end of the life span of erythrocytes. Taken together our results provide evidence for an age dependent increase in the GAF of blood erythrocytes that is accentuated by depletion of macrophages. Kinetics of changes in GAF of circulating erythrocytes with age has also been defined.

  6. Phantom limb pain

    Science.gov (United States)

    ... Philadelphia, PA: Elsevier; 2015:chap 54. Nikolajsen L, Springer JS, Haroutiunian S. Phantom limb pain. In: Benzon HT, ... medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- ...

  7. VoxelStats: A MATLAB Package for Multi-Modal Voxel-Wise Brain Image Analysis.

    Science.gov (United States)

    Mathotaarachchi, Sulantha; Wang, Seqian; Shin, Monica; Pascoal, Tharick A; Benedet, Andrea L; Kang, Min Su; Beaudry, Thomas; Fonov, Vladimir S; Gauthier, Serge; Labbe, Aurélie; Rosa-Neto, Pedro

    2016-01-01

    In healthy individuals, behavioral outcomes are highly associated with the variability on brain regional structure or neurochemical phenotypes. Similarly, in the context of neurodegenerative conditions, neuroimaging reveals that cognitive decline is linked to the magnitude of atrophy, neurochemical declines, or concentrations of abnormal protein aggregates across brain regions. However, modeling the effects of multiple regional abnormalities as determinants of cognitive decline at the voxel level remains largely unexplored by multimodal imaging research, given the high computational cost of estimating regression models for every single voxel from various imaging modalities. VoxelStats is a voxel-wise computational framework to overcome these computational limitations and to perform statistical operations on multiple scalar variables and imaging modalities at the voxel level. VoxelStats package has been developed in Matlab(®) and supports imaging formats such as Nifti-1, ANALYZE, and MINC v2. Prebuilt functions in VoxelStats enable the user to perform voxel-wise general and generalized linear models and mixed effect models with multiple volumetric covariates. Importantly, VoxelStats can recognize scalar values or image volumes as response variables and can accommodate volumetric statistical covariates as well as their interaction effects with other variables. Furthermore, this package includes built-in functionality to perform voxel-wise receiver operating characteristic analysis and paired and unpaired group contrast analysis. Validation of VoxelStats was conducted by comparing the linear regression functionality with existing toolboxes such as glim_image and RMINC. The validation results were identical to existing methods and the additional functionality was demonstrated by generating feature case assessments (t-statistics, odds ratio, and true positive rate maps). In summary, VoxelStats expands the current methods for multimodal imaging analysis by allowing the

  8. Voxel inversion of airborne EM data

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca G.; Auken, Esben; Christiansen, Anders Vest C A.V.C.;

    2013-01-01

    We present a geophysical inversion algorithm working directly in a voxel grid disconnected from the actual measuring points, which allows for straightforward integration of different data types in joint inversion, for informing geological/hydrogeological models directly and for easier incorporation...... for jointly inverting airborne and ground-based geophysical data. Furthermore, geological and groundwater models most often refer to a regular voxel grid not correlated to the geophysical model space, and incorporating the geophysical data into the geological/hydrological modelling grids is problematic. We...... present a voxel grid inversion routine that overcomes these problems and we discuss in detail the algorithm implementation....

  9. Use of VAP3D software in the construction of pathological anthropomorphic phantoms for dosimetric evaluations; Uso do software VAP3D na construcao de fantomas antropomorficos patologicos para avaliacoes dosimetricas

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Lindeval Fernandes de [Universidade Federal de Pernambuco (DEM/UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica; Vieira, Jose Wilson [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco, Recife, PE (Brazil); Lima, Fernando R.A., E-mail: falima@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2011-10-26

    This paper performs a new type of dosimetric evaluation, where it was used a phantom of pathological voxels (representative phantom of sick person). The software VAP3D (Visualization and Analysis of Phantoms 3D) were used for, from a healthy phantom (phantom representative of healthy person), to introduce three dimensional regions to simulate tumors. It was used the Monte Carlo ESGnrc code to simulate the X ray photon transport, his interaction with matter and evaluation of absorbed dose in organs and tissues from thorax region of the healthy phantom and his pathological version. This is a computer model of typical exposure for programming the treatments in radiodiagnostic

  10. VIDA: a voxel-based dosimetry method for targeted radionuclide therapy using Geant4.

    Science.gov (United States)

    Kost, Susan D; Dewaraja, Yuni K; Abramson, Richard G; Stabin, Michael G

    2015-02-01

    We have developed the Voxel-Based Internal Dosimetry Application (VIDA) to provide patient-specific dosimetry in targeted radionuclide therapy performing Monte Carlo simulations of radiation transport with the Geant4 toolkit. The code generates voxel-level dose rate maps using anatomical and physiological data taken from individual patients. Voxel level dose rate curves are then fit and integrated to yield a spatial map of radiation absorbed dose. In this article, we present validation studies using established dosimetry results, including self-dose factors (DFs) from the OLINDA/EXM program for uniform activity in unit density spheres and organ self- and cross-organ DFs in the Radiation Dose Assessment Resource (RADAR) reference adult phantom. The comparison with reference data demonstrated agreement within 5% for self-DFs to spheres and reference phantom source organs for four common radionuclides used in targeted therapy ((131)I, (90)Y, (111)In, (177)Lu). Agreement within 9% was achieved for cross-organ DFs. We also present dose estimates to normal tissues and tumors from studies of two non-Hodgkin Lymphoma patients treated by (131)I radioimmunotherapy, with comparison to results generated independently with another dosimetry code. A relative difference of 12% or less was found between methods for mean absorbed tumor doses accounting for tumor regression.

  11. Development of neonate phantom for estimating medical exposure

    Energy Technology Data Exchange (ETDEWEB)

    Akahane, K.; Kai, M.; Kusama, T. [Oita Univ. of Nursing and Health Sciences, Oita (Japan); Mitarai, T.; Ono, K.; Hada, M.; Ninomiya, H.; Kato, Y. [Oita Prefectural Hospital, Oita (Japan)

    2000-05-01

    -Carlo simulation was done by using EGS4 code. The phantom geometry was divided into voxels in order to estimate the site of energy deposition in the phantom. The dose distribution was calculated with g77 on a Linux/Alpha machine. (author)

  12. Age-dependent morphological and compositional variations on Ceres

    Science.gov (United States)

    Jaumann, Ralf

    2016-04-01

    Extended smooth plains cover the interior of a number of craters on Ceres. Smooth plains appear on different topographic levels associated with pits and flow-like features that overrun crater rims. The material forming these plains also ponds in depressions and smaller craters and cover the pre-existing surface creating distinct geological boundaries. Ikapati crater shows smooth plains on different topographic levels associated with pits and flow-like features that overrun crater rims. The material forming these plains, ponds in depressions and smaller craters and cover the pre-existing surface creating a distinct geological boundary. The interior of Occator also exhibits extended plains of ponded material, multiple flows originating from the center overwhelming the mass wasting deposits from the rim, dome-like features, vents cracks and fissures. Furthermore, crater densities on Occator's floor are lower than those on the ejecta blanket indicating a post-impact formation age of the flows. The flows to the northeast appear to originate from the central region and move slightly uphill. This indicates either a feeding zone that pushes the flows forward by supplying low-viscosity material or a depression of the crater center, possibly after discharging a subsurface reservoir. The plains and flows as well as some areas surrounding the craters appear spectrally blue. Both plains and flow material are characterized in camera and spectrometer visible spectra by a slightly negative slope with a gradual drop off up to 10% in reflectance from 0.5μm to 1μm. Although the spectral variations in the visible are subtle, they are clearly expressed in the color ratio composite. The crater densities of 20 locations across the surface of Ceres with different spectral behavior were analyzed in order to investigate the age dependence of spectral surface features. The results indicate that bluish material is mainly associated with the youngest impact craters on Ceres ( 1 Ga

  13. Voxel2MCNP: a framework for modeling, simulation and evaluation of radiation transport scenarios for Monte Carlo codes.

    Science.gov (United States)

    Pölz, Stefan; Laubersheimer, Sven; Eberhardt, Jakob S; Harrendorf, Marco A; Keck, Thomas; Benzler, Andreas; Breustedt, Bastian

    2013-08-21

    The basic idea of Voxel2MCNP is to provide a framework supporting users in modeling radiation transport scenarios using voxel phantoms and other geometric models, generating corresponding input for the Monte Carlo code MCNPX, and evaluating simulation output. Applications at Karlsruhe Institute of Technology are primarily whole and partial body counter calibration and calculation of dose conversion coefficients. A new generic data model describing data related to radiation transport, including phantom and detector geometries and their properties, sources, tallies and materials, has been developed. It is modular and generally independent of the targeted Monte Carlo code. The data model has been implemented as an XML-based file format to facilitate data exchange, and integrated with Voxel2MCNP to provide a common interface for modeling, visualization, and evaluation of data. Also, extensions to allow compatibility with several file formats, such as ENSDF for nuclear structure properties and radioactive decay data, SimpleGeo for solid geometry modeling, ImageJ for voxel lattices, and MCNPX's MCTAL for simulation results have been added. The framework is presented and discussed in this paper and example workflows for body counter calibration and calculation of dose conversion coefficients is given to illustrate its application.

  14. Jamitons: Phantom Traffic Jams

    Science.gov (United States)

    Kowszun, Jorj

    2013-01-01

    Traffic on motorways can slow down for no apparent reason. Sudden changes in speed by one or two drivers can create a chain reaction that causes a traffic jam for the vehicles that are following. This kind of phantom traffic jam is called a "jamiton" and the article discusses some of the ways in which traffic engineers produce…

  15. The Phantom brane revisited

    Science.gov (United States)

    Sahni, Varun

    2016-07-01

    The Phantom brane is based on the normal branch of the DGP braneworld. It possesses a phantom-like equation of state at late times, but no big-rip future singularity. In this braneworld, the cosmological constant is dynamically screened at late times. Consequently it provides a good fit to SDSS DR11 measurements of H(z) at high redshifts. We obtain a closed system of equations for scalar perturbations on the brane. Perturbations of radiation, matter and the Weyl fluid are self-consistently evolved until the present epoch. We find that the late time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials φ, Ψ evolve differently on the brane than in ΛCDM, for which φ = Ψ. On the Brane, by contrast, the ratio φ/Ψ exceeds unity during the late matter dominated epoch (z ≤ 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large scale structure. The phantom brane also displays a pole in its equation of state, which provides a key test of this dark energy model.

  16. The Phantom Menace

    DEFF Research Database (Denmark)

    Vium, Christian

    2013-01-01

    as a phantom menace, which asserts itself through a form of omnipresent fear, nurtured by an inherent opaqueness. As this fundamental fear progressively permeates the nomadic landscape, it engenders a recasting of mobile strategies among the nomadic pastoralist groups who inhabit the interstitial desert spaces....

  17. Construction of Chinese adult male phantom library and its application in the virtual calibration of in vivo measurement

    Science.gov (United States)

    Chen, Yizheng; Qiu, Rui; Li, Chunyan; Wu, Zhen; Li, Junli

    2016-03-01

    In vivo measurement is a main method of internal contamination evaluation, particularly for large numbers of people after a nuclear accident. Before the practical application, it is necessary to obtain the counting efficiency of the detector by calibration. The virtual calibration based on Monte Carlo simulation usually uses the reference human computational phantom, and the morphological difference between the monitored personnel with the calibrated phantom may lead to the deviation of the counting efficiency. Therefore, a phantom library containing a wide range of heights and total body masses is needed. In this study, a Chinese reference adult male polygon surface (CRAM_S) phantom was constructed based on the CRAM voxel phantom, with the organ models adjusted to match the Chinese reference data. CRAMS phantom was then transformed to sitting posture for convenience in practical monitoring. Referring to the mass and height distribution of the Chinese adult male, a phantom library containing 84 phantoms was constructed by deforming the reference surface phantom. Phantoms in the library have 7 different heights ranging from 155 cm to 185 cm, and there are 12 phantoms with different total body masses in each height. As an example of application, organ specific and total counting efficiencies of Ba-133 were calculated using the MCNPX code, with two series of phantoms selected from the library. The influence of morphological variation on the counting efficiency was analyzed. The results show only using the reference phantom in virtual calibration may lead to an error of 68.9% for total counting efficiency. Thus the influence of morphological difference on virtual calibration can be greatly reduced using the phantom library with a wide range of masses and heights instead of a single reference phantom.

  18. Voxel-Based LIDAR Analysis and Applications

    Science.gov (United States)

    Hagstrom, Shea T.

    One of the greatest recent changes in the field of remote sensing is the addition of high-quality Light Detection and Ranging (LIDAR) instruments. In particular, the past few decades have been greatly beneficial to these systems because of increases in data collection speed and accuracy, as well as a reduction in the costs of components. These improvements allow modern airborne instruments to resolve sub-meter details, making them ideal for a wide variety of applications. Because LIDAR uses active illumination to capture 3D information, its output is fundamentally different from other modalities. Despite this difference, LIDAR datasets are often processed using methods appropriate for 2D images and that do not take advantage of its primary virtue of 3-dimensional data. It is this problem we explore by using volumetric voxel modeling. Voxel-based analysis has been used in many applications, especially medical imaging, but rarely in traditional remote sensing. In part this is because the memory requirements are substantial when handling large areas, but with modern computing and storage this is no longer a significant impediment. Our reason for using voxels to model scenes from LIDAR data is that there are several advantages over standard triangle-based models, including better handling of overlapping surfaces and complex shapes. We show how incorporating system position information from early in the LIDAR point cloud generation process allows radiometrically-correct transmission and other novel voxel properties to be recovered. This voxelization technique is validated on simulated data using the Digital Imaging and Remote Sensing Image Generation (DIRSIG) software, a first-principles based ray-tracer developed at the Rochester Institute of Technology. Voxel-based modeling of LIDAR can be useful on its own, but we believe its primary advantage is when applied to problems where simpler surface-based 3D models conflict with the requirement of realistic geometry. To

  19. Gait analysis and validation using voxel data.

    Science.gov (United States)

    Wang, Fang; Stone, Erik; Dai, Wenqing; Skubic, Marjorie; Keller, James

    2009-01-01

    In this paper, we present a method for extracting gait parameters including walking speed, step time and step length from a three-dimensional voxel reconstruction, which is built from two calibrated camera views. These parameters are validated with a GAITRite Electronic mat and a Vicon motion capture system. Experiments were conducted in which subjects walked across the GAITRite mat at various speeds while the Vicon cameras recorded the motion of reflective markers attached to subjects' shoes, and our two calibrated cameras captured the images. Excellent agreements were found for walking speed. Step time and step length were also found to have good agreement given the limitation of frame rate and voxel resolution.

  20. Incorporation of ICRP-116 eye model into ICRP reference polygonal surface phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thang Tat; Yeom, Yeon Soo; Han, Min Cheol; Wang, Zhao Jun; Kim, Han Sung; Kim, Chan Hyeong [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

    2015-04-15

    The ICRP adopted a detailed stylized eye model developed by Behrens et al. for evaluation of lens dose coefficients released in ICRP publication 116. However, the dose coefficients were calculated with the stylized eye model modelled into the head of mathematical phantoms not the ICRP reference phantoms, which may cause inconsistency in lens dose assessment. In order to keep consistency in the lens dose assessment, the present study incorporates the ICRP-116 eye model into the currently developing polygonal-mesh-type ICRP reference phantoms which are being converted from the voxel-type ICRP reference phantoms. Then, lens dose values were calculated and compared with those calculated with the mathematical phantom to see how it affects lens doses. The present study incorporated the ICRP-116 eye model into the currently developing polygonal-mesh-type ICRP reference phantoms and showed significant dose differences when compared with ICRP-116 data calculated with the mathematical phantom. We believe that the ICRP reference phantoms including the detailed eye model provide more consistent assessment for eye lens dose.

  1. Voxel2MCNP: software for handling voxel models for Monte Carlo radiation transport calculations.

    Science.gov (United States)

    Hegenbart, Lars; Pölz, Stefan; Benzler, Andreas; Urban, Manfred

    2012-02-01

    Voxel2MCNP is a program that sets up radiation protection scenarios with voxel models and generates corresponding input files for the Monte Carlo code MCNPX. Its technology is based on object-oriented programming, and the development is platform-independent. It has a user-friendly graphical interface including a two- and three-dimensional viewer. A row of equipment models is implemented in the program. Various voxel model file formats are supported. Applications include calculation of counting efficiency of in vivo measurement scenarios and calculation of dose coefficients for internal and external radiation scenarios. Moreover, anthropometric parameters of voxel models, for instance chest wall thickness, can be determined. Voxel2MCNP offers several methods for voxel model manipulations including image registration techniques. The authors demonstrate the validity of the program results and provide references for previous successful implementations. The authors illustrate the reliability of calculated dose conversion factors and specific absorbed fractions. Voxel2MCNP is used on a regular basis to generate virtual radiation protection scenarios at Karlsruhe Institute of Technology while further improvements and developments are ongoing.

  2. [Phantom holder of CT couch].

    Science.gov (United States)

    Zhang, Ruixia; Zhan, Hongyu; Wang, Di

    2014-03-01

    This article describes a phantom holder in CT couch which adjusted easily and accurately, installed easily. The holder mainly include removing and locking equipment between phantom holder and table top, move horizontally equipment between left and right, rotating equipment between left and right. After holder and table top fixed one part, holder with phantom can move horizontally, front and back, rotate between left and right in a small angle, in order to make operator test phantoms accurately and easily. At the same time, this phantom holder realized free adjustment after first adjustments, which shortened operator work time.

  3. Tissue-like phantoms

    Science.gov (United States)

    Frangioni, John V.; De Grand, Alec M.

    2007-10-30

    The invention is based, in part, on the discovery that by combining certain components one can generate a tissue-like phantom that mimics any desired tissue, is simple and inexpensive to prepare, and is stable over many weeks or months. In addition, new multi-modal imaging objects (e.g., beads) can be inserted into the phantoms to mimic tissue pathologies, such as cancer, or merely to serve as calibration standards. These objects can be imaged using one, two, or more (e.g., four) different imaging modalities (e.g., x-ray computed tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), and near-infrared (NIR) fluorescence) simultaneously.

  4. Critical Age-Dependent Branching Markov Processes and their Scaling Limits

    Indian Academy of Sciences (India)

    Krishna B Athreya; Siva R Athreya; Srikanth K Iyer

    2010-06-01

    This paper studies: (i) the long-time behaviour of the empirical distribution of age and normalized position of an age-dependent critical branching Markov process conditioned on non-extinction; and (ii) the super-process limit of a sequence of age-dependent critical branching Brownian motions.

  5. The Phantom SPH code

    Science.gov (United States)

    Price, Daniel; Wurster, James; Nixon, Chris

    2016-05-01

    I will present the capabilities of the Phantom SPH code for global simulations of dust and gas in protoplanetary discs. I will present our new algorithms for simulating both small and large grains in discs, as well as our progress towards simulating evolving grain populations and coupling with radiation. Finally, I will discuss our recent applications to HL Tau and the physics of dust gap opening.

  6. Molecular and cellular mechanisms of the age-dependency of opioid analgesia and tolerance

    Directory of Open Access Journals (Sweden)

    Zhao Jing

    2012-05-01

    Full Text Available Abstract The age-dependency of opioid analgesia and tolerance has been noticed in both clinical observation and laboratory studies. Evidence shows that many molecular and cellular events that play essential roles in opioid analgesia and tolerance are actually age-dependent. For example, the expression and functions of endogenous opioid peptides, multiple types of opioid receptors, G protein subunits that couple to opioid receptors, and regulators of G protein signaling (RGS proteins change with development and age. Other signaling systems that are critical to opioid tolerance development, such as N-methyl-D-aspartic acid (NMDA receptors, also undergo age-related changes. It is plausible that the age-dependent expression and functions of molecules within and related to the opioid signaling pathways, as well as age-dependent cellular activity such as agonist-induced opioid receptor internalization and desensitization, eventually lead to significant age-dependent changes in opioid analgesia and tolerance development.

  7. Uncertainty driven probabilistic voxel selection for image registration.

    Science.gov (United States)

    Oreshkin, Boris N; Arbel, Tal

    2013-10-01

    This paper presents a novel probabilistic voxel selection strategy for medical image registration in time-sensitive contexts, where the goal is aggressive voxel sampling (e.g., using less than 1% of the total number) while maintaining registration accuracy and low failure rate. We develop a Bayesian framework whereby, first, a voxel sampling probability field (VSPF) is built based on the uncertainty on the transformation parameters. We then describe a practical, multi-scale registration algorithm, where, at each optimization iteration, different voxel subsets are sampled based on the VSPF. The approach maximizes accuracy without committing to a particular fixed subset of voxels. The probabilistic sampling scheme developed is shown to manage the tradeoff between the robustness of traditional random voxel selection (by permitting more exploration) and the accuracy of fixed voxel selection (by permitting a greater proportion of informative voxels).

  8. Schizophrenia Patients Demonstrate Both Inter-Voxel Level and Intra-Voxel Level White Matter Alterations.

    Science.gov (United States)

    Zhuo, Chuanjun; Ma, Xiaolei; Qu, Hongru; Wang, Lina; Jia, Feng; Wang, Chunli

    2016-01-01

    Fractional anisotropy (FA) and mean diffusivity (MD) are the most frequently used metrics to investigate white matter impairments in mental disorders. However, these two metrics are derived from intra-voxel analyses and only reflect the diffusion properties solely within the voxel unit. Local diffusion homogeneity (LDH) is a newly developed inter-voxel metric which quantifies the local coherence of water molecule diffusion in a model-free manner. In this study, 94 schizophrenia patients and 91 sex- and age-matched healthy controls underwent diffusion tensor imaging (DTI) examinations. White matter integrity was assessed by FA, MD and LDH. Group differences in these metrics were compared using tract-based spatial statistics (TBSS). Compared with healthy controls, schizophrenia patients exhibited reduced FA and increased MD in the corpus callosum, cingulum, internal capsule, fornix and widespread superficial white matter in the frontal, parietal, occipital and temporal lobes. We also found decreased LDH in the corpus callosum, cingulum, internal capsule and fornix in schizophrenia. Our findings suggest that both intra-voxel and inter-voxel diffusion metrics are able to detect impairments in the anisotropic white matter regions, and intra-voxel diffusion metrics could detect additional impairments in the widespread isotropic white matter regions in schizophrenia.

  9. Development and tests of a mouse voxel model dor MCNPX based on Digimouse images

    Energy Technology Data Exchange (ETDEWEB)

    Melo M, B.; Ferreira F, C. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Pte. Antonio Carlos No. 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil); Garcia de A, I.; Machado T, B.; Passos Ribeiro de C, T., E-mail: bmm@cdtn.br [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Pte. Antonio Carlos 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil)

    2015-10-15

    Mice have been widely used in experimental protocols involving ionizing radiation. Biological effects (Be) induced by radiation can compromise studies results. Good estimates of mouse whole body and organs absorbed dose could provide valuable information to researchers. The aim of this study was to create and test a new voxel phantom for mice dosimetry from -Digimouse- project images. Micro CT images from Digimouse project were used in this work. Corel PHOTOPAINT software was utilized in segmentation process. The three-dimensional (3-D) model assembly and its voxel size manipulation were performed by Image J. SISCODES was used to adapt the model to run in MCNPX Monte Carlo code. The resulting model was called DM{sub B}RA. The volume and mass of segmented organs were compared with data available in literature. For the preliminary tests the heart was considered the source organ. Photons of diverse energies were simulated and Saf values obtained through F6:p and + F6 MCNPX tallies. The results were compared with reference data. 3-D picturing of absorbed doses patterns and relative errors distribution were generated by a C++ -in house- made program and visualized through Amide software. The organ masses of DM{sub B}RA correlated well with two models that were based on same set of images. However some organs, like eyes and adrenals, skeleton and brain showed large discrepancies. Segmentation of an identical image set by different persons and/or methods can result significant organ masses variations. We believe that the main causes of these differences were: i) operator dependent subjectivity in the definition of organ limits during the segmentation processes; and i i) distinct voxel dimensions between evaluated models. Lack of reference data for mice models construction and dosimetry was detected. Comparison with other models originated from different mice strains also demonstrated that the anatomical and size variability can be significant. Use of + F6 tally for mouse

  10. Phantom stars and topology change

    CERN Document Server

    DeBenedictis, Andrew; Lobo, Francisco S N

    2008-01-01

    In this work, we consider time-dependent dark energy star models, with an evolving parameter $\\omega$ crossing the phantom divide, $\\omega=-1$. Once in the phantom regime, the null energy condition is violated, which physically implies that the negative radial pressure exceeds the energy density. Therefore, an enormous negative pressure in the center may, in principle, imply a topology change, consequently opening up a tunnel and converting the dark energy star into a wormhole. The criteria for this topology change are discussed, in particular, we consider the Morse Index analysis and a Casimir energy approach involving quasi-local energy difference calculations that may reflect or measure the occurrence of a topology change. We denote these exotic geometries consisting of dark energy stars (in the phantom regime) and phantom wormholes as phantom stars. The final product of this topological change, namely, phantom wormholes, have far-reaching physical and cosmological implications, as in addition to being use...

  11. Multi-Modality Phantom Development

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Jennifer S.; Peng, Qiyu; Moses, William W.

    2009-03-20

    Multi-modality imaging has an increasing role in the diagnosis and treatment of a large number of diseases, particularly if both functional and anatomical information are acquired and accurately co-registered. Hence, there is a resulting need for multi modality phantoms in order to validate image co-registration and calibrate the imaging systems. We present our PET-ultrasound phantom development, including PET and ultrasound images of a simple prostate phantom. We use agar and gelatin mixed with a radioactive solution. We also present our development of custom multi-modality phantoms that are compatible with PET, transrectal ultrasound (TRUS), MRI and CT imaging. We describe both our selection of tissue mimicking materials and phantom construction procedures. These custom PET-TRUS-CT-MRI prostate phantoms use agargelatin radioactive mixtures with additional contrast agents and preservatives. We show multi-modality images of these custom prostate phantoms, as well as discuss phantom construction alternatives. Although we are currently focused on prostate imaging, this phantom development is applicable to many multi-modality imaging applications.

  12. Modeling and analysis of caves using voxelization

    Science.gov (United States)

    Szeifert, Gábor; Szabó, Tivadar; Székely, Balázs

    2014-05-01

    Although there are many ways to create three dimensional representations of caves using modern information technology methods, modeling of caves has been challenging for researchers for a long time. One of these promising new alternative modeling methods is using voxels. We are using geodetic measurements as an input for our voxelization project. These geodetic underground surveys recorded the azimuth, altitude and distance of corner points of cave systems relative to each other. The diameter of each cave section is estimated from separate databases originating from different surveys. We have developed a simple but efficient method (it covers more than 99.9 % of the volume of the input model on the average) to convert these vector-type datasets to voxels. We have also developed software components to make visualization of the voxel and vector models easier. Since each cornerpoint position is measured relative to another cornerpoints positions, propagation of uncertainties is an important issue in case of long caves with many separate sections. We are using Monte Carlo simulations to analyze the effect of the error of each geodetic instrument possibly involved in a survey. Cross-sections of the simulated three dimensional distributions show, that even tiny uncertainties of individual measurements can result in high variation of positions that could be reduced by distributing the closing errors if such data are available. Using the results of our simulations, we can estimate cave volume and the error of the calculated cave volume depending on the complexity of the cave. Acknowledgements: the authors are grateful to Ariadne Karst and Cave Exploring Association and State Department of Environmental and Nature Protection of the Hungarian Ministry of Rural Development, Department of National Parks and Landscape Protection, Section Landscape and Cave Protection and Ecotourism for providing the cave measurement data. BS contributed as an Alexander von Humboldt Research

  13. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, R; Cassola, V F; Khoury, H J [Department of Nuclear Energy, Federal University of Pernambuco, Avenida Prof. Luiz Freire, 1000, CEP 50740-540, Recife (Brazil); Vieira, J W [Federal Institute of Education, Science and Technology of Pernambuco, Recife (Brazil); De Melo Lima, V J [Department of Anatomy, Federal University of Pernambuco, Recife (Brazil); Robson Brown, K [Imaging Laboratory, Department of Archaeology and Anthropology, University of Bristol, Bristol (United Kingdom)], E-mail: rkramer@uol.com.br

    2010-01-07

    Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon

  14. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations

    Science.gov (United States)

    Kramer, R.; Cassola, V. F.; Khoury, H. J.; Vieira, J. W.; de Melo Lima, V. J.; Robson Brown, K.

    2010-01-01

    Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon

  15. Computer simulations for internal dosimetry using voxel models.

    Science.gov (United States)

    Kinase, Sakae; Mohammadi, Akram; Takahashi, Masa; Saito, Kimiaki; Zankl, Maria; Kramer, Richard

    2011-07-01

    In the Japan Atomic Energy Agency, several studies have been conducted on the use of voxel models for internal dosimetry. Absorbed fractions (AFs) and S values have been evaluated for preclinical assessments of radiopharmaceuticals using human voxel models and a mouse voxel model. Computational calibration of in vivo measurement system has been also made using Japanese and Caucasian voxel models. In addition, for radiation protection of the environment, AFs have been evaluated using a frog voxel model. Each study was performed by using Monte Carlo simulations. Consequently, it was concluded that these data of Monte Carlo simulations and voxel models could adequately reproduce measurement results. Voxel models were found to be a significant tool for internal dosimetry since the models are anatomically realistic. This fact indicates that several studies on correction of the in vivo measurement efficiency for the variability of human subjects and interspecies scaling of organ doses will succeed.

  16. Computerized MRS voxel registration and partial volume effects in single voxel 1H-MRS.

    Science.gov (United States)

    Lee, Hedok; Caparelli, Elisabeth; Li, Haifang; Mandal, Amit; Smith, S David; Zhang, Shaonan; Bilfinger, Thomas V; Benveniste, Helene

    2013-09-01

    Partial volume effects in proton magnetic resonance spectroscopy in the brain have been studied previously in terms of proper water concentration calculations, but there is a lack of disclosure in terms of voxel placement techniques that would affect the calculations. The purpose of this study is to facilitate a fully automated MRS voxel registration method which is time efficient, accurate, and can be extended to all imaging modalities. A total of thirteen healthy adults underwent single voxel 1H-MRS scans in 3.0T MRI scanners. Transposition of a MRS voxel onto an anatomical scan is derived along with a full calculation of water concentration with a correction term to account for the partial volume effects. Five metabolites (tNAA, Glx, tCr, mI, and tCho) known to yield high reliability are studied. Pearson's correlation analyses between tissue volume fractions and metabolite concentrations were statistically significant in parietal (tCr, Glx, and tNAA) lobe and occipital lobe (tNAA). MRS voxel overlaps quantified by dice metric over repeated visits yielded 60%~70% and coefficients of variance in metabolites concentration were 4%~10%. These findings reiterate an importance of considering the partial volume effects when tissue water is used as an internal concentration reference so as to avoid misinterpreting a morphometric difference as a metabolic difference.

  17. Phantom pain after eye amputation

    DEFF Research Database (Denmark)

    Rasmussen, Marie L R; Prause, Jan U; Toft, Peter B

    2011-01-01

    Purpose: To characterize the quality of phantom pain, its intensity and frequency following eye amputation. Possible triggers and relievers of phantom pain are investigated. Methods: The hospital database was searched using surgery codes for patients who received ocular evisceration, enucleation......, orbital exenteration or secondary implantation of an orbital implant in the period between 1993 and 2003. A total of 267 patients were identified and invited to participate; of these, 173 agreed to participate. These patients’ medical records were reviewed. A structured interview focusing on pain...... was conducted by a trained interviewer. Results: Of the 173 patients in the study, 39 experienced phantom pain. The median age of patients who had experienced phantom pain was 45 years (range: 19–88). Follow-up time from eye amputation to participation in the investigation was 4 years (range: 2–46). Phantom...

  18. Investigation of Nonuniform Dose Voxel Geometry in Monte Carlo Calculations.

    Science.gov (United States)

    Yuan, Jiankui; Chen, Quan; Brindle, James; Zheng, Yiran; Lo, Simon; Sohn, Jason; Wessels, Barry

    2015-08-01

    The purpose of this work is to investigate the efficacy of using multi-resolution nonuniform dose voxel geometry in Monte Carlo (MC) simulations. An in-house MC code based on the dose planning method MC code was developed in C++ to accommodate the nonuniform dose voxel geometry package since general purpose MC codes use their own coupled geometry packages. We devised the package in a manner that the entire calculation volume was first divided into a coarse mesh and then the coarse mesh was subdivided into nonuniform voxels with variable voxel sizes based on density difference. We name this approach as multi-resolution subdivision (MRS). It generates larger voxels in small density gradient regions and smaller voxels in large density gradient regions. To take into account the large dose gradients due to the beam penumbra, the nonuniform voxels can be further split using ray tracing starting from the beam edges. The accuracy of the implementation of the algorithm was verified by comparing with the data published by Rogers and Mohan. The discrepancy was found to be 1% to 2%, with a maximum of 3% at the interfaces. Two clinical cases were used to investigate the efficacy of nonuniform voxel geometry in the MC code. Applying our MRS approach, we started with the initial voxel size of 5 × 5 × 3 mm(3), which was further divided into smaller voxels. The smallest voxel size was 1.25 × 1.25 × 3 mm(3). We found that the simulation time per history for the nonuniform voxels is about 30% to 40% faster than the uniform fine voxels (1.25 × 1.25 × 3 mm(3)) while maintaining similar accuracy.

  19. Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation.

    Science.gov (United States)

    Sun, Wenjuan; Jia, Xianghong; Xie, Tianwu; Xu, Feng; Liu, Qian

    2013-03-01

    With the rapid development of China's space industry, the importance of radiation protection is increasingly prominent. To provide relevant dose data, we first developed the Visible Chinese Human adult Female (VCH-F) phantom, and performed further modifications to generate the VCH-F Astronaut (VCH-FA) phantom, incorporating statistical body characteristics data from the first batch of Chinese female astronauts as well as reference organ mass data from the International Commission on Radiological Protection (ICRP; both within 1% relative error). Based on cryosection images, the original phantom was constructed via Non-Uniform Rational B-Spline (NURBS) boundary surfaces to strengthen the deformability for fitting the body parameters of Chinese female astronauts. The VCH-FA phantom was voxelized at a resolution of 2 × 2 × 4 mm(3)for radioactive particle transport simulations from isotropic protons with energies of 5000-10 000 MeV in Monte Carlo N-Particle eXtended (MCNPX) code. To investigate discrepancies caused by anatomical variations and other factors, the obtained doses were compared with corresponding values from other phantoms and sex-averaged doses. Dose differences were observed among phantom calculation results, especially for effective dose with low-energy protons. Local skin thickness shifts the breast dose curve toward high energy, but has little impact on inner organs. Under a shielding layer, organ dose reduction is greater for skin than for other organs. The calculated skin dose per day closely approximates measurement data obtained in low-Earth orbit (LEO).

  20. Multistep Lattice-Voxel method utilizing lattice function for Monte-Carlo treatment planning with pixel based voxel model.

    Science.gov (United States)

    Kumada, H; Saito, K; Nakamura, T; Sakae, T; Sakurai, H; Matsumura, A; Ono, K

    2011-12-01

    Treatment planning for boron neutron capture therapy generally utilizes Monte-Carlo methods for calculation of the dose distribution. The new treatment planning system JCDS-FX employs the multi-purpose Monte-Carlo code PHITS to calculate the dose distribution. JCDS-FX allows to build a precise voxel model consisting of pixel based voxel cells in the scale of 0.4×0.4×2.0 mm(3) voxel in order to perform high-accuracy dose estimation, e.g. for the purpose of calculating the dose distribution in a human body. However, the miniaturization of the voxel size increases calculation time considerably. The aim of this study is to investigate sophisticated modeling methods which can perform Monte-Carlo calculations for human geometry efficiently. Thus, we devised a new voxel modeling method "Multistep Lattice-Voxel method," which can configure a voxel model that combines different voxel sizes by utilizing the lattice function over and over. To verify the performance of the calculation with the modeling method, several calculations for human geometry were carried out. The results demonstrated that the Multistep Lattice-Voxel method enabled the precise voxel model to reduce calculation time substantially while keeping the high-accuracy of dose estimation.

  1. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Science.gov (United States)

    Yani, Sitti; Dirgayussa, I. Gde E.; Rhani, Moh. Fadhillah; Haryanto, Freddy; Arif, Idam

    2015-09-01

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm3, 1 × 1 × 0.5 cm3, and 1 × 1 × 0.8 cm3. The 1 × 109 histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in dmax from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm3 about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm3 about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  2. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yani, Sitti, E-mail: sitti.yani@s.itb.ac.id [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Akademi Kebidanan Pelita Ibu, Kendari (Indonesia); Dirgayussa, I Gde E.; Haryanto, Freddy; Arif, Idam [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Rhani, Moh. Fadhillah [Tan Tock Seng Hospital (Singapore)

    2015-09-30

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm{sup 3}, 1 × 1 × 0.5 cm{sup 3}, and 1 × 1 × 0.8 cm{sup 3}. The 1 × 10{sup 9} histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in d{sub max} from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm{sup 3} about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm{sup 3} about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  3. Age-dependent arginine phosphokinase activity changes in male vestigial and wild-type Drosophila melanogaster.

    Science.gov (United States)

    Baker, G T

    1975-01-01

    The activity of arginine phosphokinase, an important muscle enzyme in insects, was investigated with age in vestigial-winged and wild-type Drosophila melanogaster. Identical patterns of age-dependent activity changes were observed in the vestigial-winged flies as in the wild-type, even though vestigial-winged flies exhibit a 50% mortality approximately two thirds that of the wild-type as well as being incapable of flight. Results indicate that the age-dependent changes in arginine phosphokinase activity are intrinsically regulated within the cells of the flight muscle.

  4. Automatic generation of digital anthropomorphic phantoms from simulated MRI acquisitions

    Science.gov (United States)

    Lindsay, C.; Gennert, M. A.; KÓ§nik, A.; Dasari, P. K.; King, M. A.

    2013-03-01

    In SPECT imaging, motion from patient respiration and body motion can introduce image artifacts that may reduce the diagnostic quality of the images. Simulation studies using numerical phantoms with precisely known motion can help to develop and evaluate motion correction algorithms. Previous methods for evaluating motion correction algorithms used either manual or semi-automated segmentation of MRI studies to produce patient models in the form of XCAT Phantoms, from which one calculates the transformation and deformation between MRI study and patient model. Both manual and semi-automated methods of XCAT Phantom generation require expertise in human anatomy, with the semiautomated method requiring up to 30 minutes and the manual method requiring up to eight hours. Although faster than manual segmentation, the semi-automated method still requires a significant amount of time, is not replicable, and is subject to errors due to the difficulty of aligning and deforming anatomical shapes in 3D. We propose a new method for matching patient models to MRI that extends the previous semi-automated method by eliminating the manual non-rigid transformation. Our method requires no user supervision and therefore does not require expert knowledge of human anatomy to align the NURBs to anatomical structures in the MR image. Our contribution is employing the SIMRI MRI simulator to convert the XCAT NURBs to a voxel-based representation that is amenable to automatic non-rigid registration. Then registration is used to transform and deform the NURBs to match the anatomy in the MR image. We show that our automated method generates XCAT Phantoms more robustly and significantly faster than the previous semi-automated method.

  5. Atypical Odontalgia (Phantom Tooth Pain)

    Science.gov (United States)

    ... atypical facial pain, phantom tooth pain, or neuropathic orofacial pain, is characterized by chronic pain in a ... such as a specialist in oral medicine or orofacial pain. The information contained in this monograph is ...

  6. Organosilicon phantom for photoacoustic imaging.

    Science.gov (United States)

    Avigo, Cinzia; Di Lascio, Nicole; Armanetti, Paolo; Kusmic, Claudia; Cavigli, Lucia; Ratto, Fulvio; Meucci, Sandro; Masciullo, Cecilia; Cecchini, Marco; Pini, Roberto; Faita, Francesco; Menichetti, Luca

    2015-04-01

    Photoacoustic imaging is an emerging technique. Although commercially available photoacoustic imaging systems currently exist, the technology is still in its infancy. Therefore, the design of stable phantoms is essential to achieve semiquantitative evaluation of the performance of a photoacoustic system and can help optimize the properties of contrast agents. We designed and developed a polydimethylsiloxane (PDMS) phantom with exceptionally fine geometry; the phantom was tested using photoacoustic experiments loaded with the standard indocyanine green dye and compared to an agar phantom pattern through polyethylene glycol-gold nanorods. The linearity of the photoacoustic signal with the nanoparticle number was assessed. The signal-tonoiseratio and contrast were employed as image quality parameters, and enhancements of up to 50 and up to 300%, respectively, were measured with the PDMS phantom with respect to the agar one. A tissue-mimicking (TM)-PDMS was prepared by adding TiO2 and India ink; photoacoustic tests were performed in order to compare the signal generated by the TM-PDMS and the biological tissue. The PDMS phantom can become a particularly promising tool in the field of photoacoustics for the evaluation of the performance of a PA system and as a model of the structure of vascularized soft tissues.

  7. An age-dependent population equation with diffusion and delayed birth process

    Directory of Open Access Journals (Sweden)

    G. Fragnelli

    2005-01-01

    Full Text Available We propose a new age-dependent population equation which takes into account not only a delay in the birth process, but also other events that may take place during the time between conception and birth. Using semigroup theory, we discuss the well posedness and the asymptotic behavior of the solution.

  8. Optimal harvesting for an age-dependent n-dimensional food chain model

    Institute of Scientific and Technical Information of China (English)

    LUO Zhi-xue; DU Ming-yin

    2008-01-01

    This paper is concerned with optimal harvesting policy for an age-dependent n-dimensional food chain model. The existence and uniqueness of non-negative solution of the system are proved using the fixed point theorem. By Mazur's theorem, the existence of optimal control strategy is demonstrated and optimality conditions derived by means of normal cone.

  9. OPTIMAL CONTROL PROBLEM FOR A PERIODIC PREDATOR-PREY MODEL WITH AGE-DEPENDENCE

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,we investigate optimal policy for periodic predator-prey system with age-dependence.Namely,we consider the model with periodic vital rates and initial distribution.The existence of optimal control strategy is discussed by Mazur's theorem and optimality condition is derived by means of normal cone.

  10. OPTIMAL BIRTH CONTROL FOR AN AGE-DEPENDENT COMPETITION SYSTEM OF N SPECIES

    Institute of Scientific and Technical Information of China (English)

    Zhixue LUO

    2007-01-01

    In this paper, we investigate optimal policies for an age-dependent n-dimensional competition system, which is controlled by fertility. By using Dubovitskii-Milyutin's general theory, the maximum principles are obtained for the problems with free terminal states, infinite horizon, and target sets, respectively.

  11. Molecular Correlates of Age-Dependent Seizures in an Inherited Neonatal-Infantile Epilepsy

    Science.gov (United States)

    Liao, Yunxiang; Deprez, Liesbet; Maljevic, Snezana; Pitsch, Julika; Claes, Lieve; Hristova, Dimitrina; Jordanova, Albena; Ala-Mello, Sirpa; Bellan-Koch, Astrid; Blazevic, Dragica; Schubert, Simone; Thomas, Evan A.; Petrou, Steven; Becker, Albert J.; De Jonghe, Peter; Lerche, Holger

    2010-01-01

    Many idiopathic epilepsy syndromes have a characteristic age dependence, the underlying molecular mechanisms of which are largely unknown. Here we propose a mechanism that can explain that epileptic spells in benign familial neonatal-infantile seizures occur almost exclusively during the first days to months of life. Benign familial…

  12. Parent perceived quality of life is age-dependent in children with food allergy

    NARCIS (Netherlands)

    Wassenberg, Jacqueline; Cochard, Marie-Madeleine; DunnGalvin, Audrey; Ballabeni, Pierluigi; Flokstra-de Blok, Bertine M. J.; Newman, Christopher J.; Hofer, Michael; Eigenmann, Philippe A.

    2012-01-01

    To cite this article: Wassenberg J, Cochard M-M, DunnGalvin A, Ballabeni P, Flokstra-de Blok BMJ, Newman CJ, Hofer M, Eigenmann PA. Parent perceived quality of life is age-dependent in children with food allergy. Pediatr Allergy Immunol 2012: 23: 412419. Abstract Background: Food allergy in children

  13. Aging-dependent changes in the cellular composition of the mouse brain and spinal cord.

    Science.gov (United States)

    Fu, Y; Yu, Y; Paxinos, G; Watson, C; Rusznák, Z

    2015-04-02

    Although the impact of aging on the function of the central nervous system is known, only a limited amount of information is available about accompanying changes affecting the cellular composition of the brain and spinal cord. In the present work we used the isotropic fractionator method to reveal aging-associated changes in the numbers of neuronal and non-neuronal cells harbored by the brain and spinal cord. The experiments were performed on 15-week, 7-month, 13-month, and 25-month-old female mice. The major parts of the brain were studied separately, including the isocortex, hippocampus, cerebellum, olfactory bulb, and the remaining part (i.e., 'rest of brain'). The proliferative capacity of each structure was assessed by counting the number of Ki-67-positive cells. We found no aging-dependent change when the cellular composition of the isocortex was studied. In contrast, the neuronal and non-neuronal cell numbers of the hippocampus decreased in the 7-25-month period. The neuronal cell number of the olfactory bulb showed positive age-dependence between 15 weeks and 13 months of age and presented a significant decrease thereafter. The cerebellum was characterized by an age-dependent decrease of its neuronal cell number and density. In the rest of brain, the non-neuronal cell number increased with age. The neuronal and non-neuronal cell numbers of the spinal cord increased, whereas its neuronal and non-neuronal densities decreased with age. The number of proliferating cells showed a marked age-dependent decrease in the hippocampus, olfactory bulb, and rest of the brain. In contrast, the number of Ki-67-positive cells increased with age in both the cerebellum and spinal cord. In conclusion, aging-dependent changes affecting the cellular composition of the mouse central nervous system are present but they are diverse and region-specific.

  14. A Fully GPU-Based Ray-Driven Backprojector via a Ray-Culling Scheme with Voxel-Level Parallelization for Cone-Beam CT Reconstruction.

    Science.gov (United States)

    Park, Hyeong-Gyu; Shin, Yeong-Gil; Lee, Ho

    2015-12-01

    A ray-driven backprojector is based on ray-tracing, which computes the length of the intersection between the ray paths and each voxel to be reconstructed. To reduce the computational burden caused by these exhaustive intersection tests, we propose a fully graphics processing unit (GPU)-based ray-driven backprojector in conjunction with a ray-culling scheme that enables straightforward parallelization without compromising the high computing performance of a GPU. The purpose of the ray-culling scheme is to reduce the number of ray-voxel intersection tests by excluding rays irrelevant to a specific voxel computation. This rejection step is based on an axis-aligned bounding box (AABB) enclosing a region of voxel projection, where eight vertices of each voxel are projected onto the detector plane. The range of the rectangular-shaped AABB is determined by min/max operations on the coordinates in the region. Using the indices of pixels inside the AABB, the rays passing through the voxel can be identified and the voxel is weighted as the length of intersection between the voxel and the ray. This procedure makes it possible to reflect voxel-level parallelization, allowing an independent calculation at each voxel, which is feasible for a GPU implementation. To eliminate redundant calculations during ray-culling, a shared-memory optimization is applied to exploit the GPU memory hierarchy. In experimental results using real measurement data with phantoms, the proposed GPU-based ray-culling scheme reconstructed a volume of resolution 28032803176 in 77 seconds from 680 projections of resolution 10243768 , which is 26 times and 7.5 times faster than standard CPU-based and GPU-based ray-driven backprojectors, respectively. Qualitative and quantitative analyses showed that the ray-driven backprojector provides high-quality reconstruction images when compared with those generated by the Feldkamp-Davis-Kress algorithm using a pixel-driven backprojector, with an average of 2.5 times

  15. Development of a pregnant woman phantom using polygonal mesh, for dosimetric evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Manuela O.M.; Vieira, Jose W., E-mail: manuela.omc@gmail.com [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear; Leal Neto, Viriato, E-mail: viriatoleal@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil); Lima, Fernando R.A., E-mail: falima@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2014-07-01

    Due to the embryo/fetus radiosensitivity the accurate estimation of the absorbed dose distribution in the abdominal area is an additional problem caused by the exposure of pregnant women to ionizing radiation in medical applications. This paper reports the construction and insertion of a fetal representation in a female geometry by means of 3D modeling techniques. In order to characterize an ECM the Grupo de Dosimetria Numerica (GDN) is using, mainly, simulators emitting gamma sources and voxel phantoms coupled to a MC code. The phantoms are predominantly constructed from stacks of magnetic resonance images (MRI), computed tomography (CT) (obtained from scans of real patients) or from 3D modeling techniques. Due to the difficulty of obtaining medical images of pregnant women, 3D objects in several formats (.obj, .max, .blend, etc.) were acquired for anatomical representation of a non-pregnant adult. To construct a fetal representation, the 3D modeling technique called Poly Modeling (polygon mesh) was used inside of the software Autodesk 3ds Max 2014 (free student version). Information about the radiosensibility of organs included in the abdominal area will be used to fit and use the pregnant phantom in numerical dosimetry. For this, the phantom will be voxelized and the masses of organs of interest will be adjusted according to data provided by International Commission on Radiological Protection (ICRP). Finally, the phantom will be coupled to a MC code creating a MCE that will serve as base for the construction of several other models involving pregnant women submitted to ionizing radiation. (author)

  16. A new, open-source, multi-modality digital breast phantom

    Science.gov (United States)

    Graff, Christian G.

    2016-03-01

    An anthropomorphic digital breast phantom has been developed with the goal of generating random voxelized breast models that capture the anatomic variability observed in vivo. This is a new phantom and is not based on existing digital breast phantoms or segmentation of patient images. It has been designed at the outset to be modality agnostic (i.e., suitable for use in modeling x-ray based imaging systems, magnetic resonance imaging, and potentially other imaging systems) and open source so that users may freely modify the phantom to suit a particular study. In this work we describe the modeling techniques that have been developed, the capabilities and novel features of this phantom, and study simulated images produced from it. Starting from a base quadric, a series of deformations are performed to create a breast with a particular volume and shape. Initial glandular compartments are generated using a Voronoi technique and a ductal tree structure with terminal duct lobular units is grown from the nipple into each compartment. An additional step involving the creation of fat and glandular lobules using a Perlin noise function is performed to create more realistic glandular/fat tissue interfaces and generate a Cooper's ligament network. A vascular tree is grown from the chest muscle into the breast tissue. Breast compression is performed using a neo-Hookean elasticity model. We show simulated mammographic and T1-weighted MRI images and study properties of these images.

  17. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: I. Development of the anatomy

    Science.gov (United States)

    Cassola, V. F.; de Melo Lima, V. J.; Kramer, R.; Khoury, H. J.

    2010-01-01

    Among computational models, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images of patients, volunteers or cadavers have become popular in recent years. Although being true to nature representations of scanned individuals, voxel phantoms have limitations, especially when walled organs have to be segmented or when volumes of organs or body tissues, like adipose, have to be changed. Additionally, the scanning of patients or volunteers is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the regular anatomy of a person in the upright position, which in turn can influence organ and tissue absorbed or equivalent dose estimates. This study applies tools developed recently in the areas of computer graphics and animated films to the creation and modelling of 3D human organs, tissues, skeletons and bodies based on polygon mesh surfaces. Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been designed using software, such as MakeHuman, Blender, Binvox and ImageJ, based on anatomical atlases, observing at the same time organ masses recommended by the International Commission on Radiological Protection for the male and female reference adult in report no 89. 113 organs, bones and tissues have been modelled in the FASH and the MASH phantoms representing locations for adults in standing posture. Most organ and tissue masses of the voxelized versions agree with corresponding data from ICRP89 within a margin of 2.6%. Comparison with the mesh-based male RPI_AM and female RPI_AF phantoms shows differences with respect to the material used, to the software and concepts applied, and to the anatomies created.

  18. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: I. Development of the anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Cassola, V F; Kramer, R; Khoury, H J [Department of Nuclear Energy, Federal University of Pernambuco, Avenida Prof. Luiz Freire, 1000, CEP 50740-540, Recife (Brazil); De Melo Lima, V J [Department of Anatomy, Federal University of Pernambuco, Avenida Prof. Moraes Rego, 1235, CEP 50670-901, Recife (Brazil)], E-mail: rkramer@uol.com.br

    2010-01-07

    Among computational models, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images of patients, volunteers or cadavers have become popular in recent years. Although being true to nature representations of scanned individuals, voxel phantoms have limitations, especially when walled organs have to be segmented or when volumes of organs or body tissues, like adipose, have to be changed. Additionally, the scanning of patients or volunteers is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the regular anatomy of a person in the upright position, which in turn can influence organ and tissue absorbed or equivalent dose estimates. This study applies tools developed recently in the areas of computer graphics and animated films to the creation and modelling of 3D human organs, tissues, skeletons and bodies based on polygon mesh surfaces. Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been designed using software, such as MakeHuman, Blender, Binvox and ImageJ, based on anatomical atlases, observing at the same time organ masses recommended by the International Commission on Radiological Protection for the male and female reference adult in report no 89. 113 organs, bones and tissues have been modelled in the FASH and the MASH phantoms representing locations for adults in standing posture. Most organ and tissue masses of the voxelized versions agree with corresponding data from ICRP89 within a margin of 2.6%. Comparison with the mesh-based male RPI{sub A}M and female RPI{sub A}F phantoms shows differences with respect to the material used, to the software and concepts applied, and to the anatomies created.

  19. MCNPX Cosmic Ray Shielding Calculations with the NORMAN Phantom Model

    Science.gov (United States)

    James, Michael R.; Durkee, Joe W.; McKinney, Gregg; Singleterry Robert

    2008-01-01

    The United States is planning manned lunar and interplanetary missions in the coming years. Shielding from cosmic rays is a critical aspect of manned spaceflight. These ventures will present exposure issues involving the interplanetary Galactic Cosmic Ray (GCR) environment. GCRs are comprised primarily of protons (approx.84.5%) and alpha-particles (approx.14.7%), while the remainder is comprised of massive, highly energetic nuclei. The National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) has commissioned a joint study with Los Alamos National Laboratory (LANL) to investigate the interaction of the GCR environment with humans using high-fidelity, state-of-the-art computer simulations. The simulations involve shielding and dose calculations in order to assess radiation effects in various organs. The simulations are being conducted using high-resolution voxel-phantom models and the MCNPX[1] Monte Carlo radiation-transport code. Recent advances in MCNPX physics packages now enable simulated transport over 2200 types of ions of widely varying energies in large, intricate geometries. We report here initial results obtained using a GCR spectrum and a NORMAN[3] phantom.

  20. Age-dependent changes in mitochondrial morphology and volume are not predictors of lifespan.

    Science.gov (United States)

    Regmi, Saroj G; Rolland, Stéphane G; Conradt, Barbara

    2014-02-01

    Mitochondrial dysfunction is a hallmark of skeletal muscle degeneration during aging. One mechanism through which mitochondrial dysfunction can be caused is through changes in mitochondrial morphology. To determine the role of mitochondrial morphology changes in age-dependent mitochondrial dysfunction, we studied mitochondrial morphology in body wall muscles of the nematodeC. elegans. We found that in this tissue, animals display a tubular mitochondrial network, which fragments with increasing age. This fragmentation is accompanied by a decrease in mitochondrial volume. Mitochondrial fragmentation and volume loss occur faster under conditions that shorten lifespan and occur slower under conditions that increase lifespan. However, neither mitochondrial morphology nor mitochondrial volume of five- and seven-day old wild-type animals can be used to predict individual lifespan. Our results indicate that while mitochondria in body wall muscles undergo age-dependent fragmentation and a loss in volume, these changes are not the cause of aging but rather a consequence of the aging process.

  1. MLE and Bayesian inference of age-dependent sensitivity and transition probability in periodic screening.

    Science.gov (United States)

    Wu, Dongfeng; Rosner, Gary L; Broemeling, Lyle

    2005-12-01

    This article extends previous probability models for periodic breast cancer screening examinations. The specific aim is to provide statistical inference for age dependence of sensitivity and the transition probability from the disease free to the preclinical state. The setting is a periodic screening program in which a cohort of initially asymptomatic women undergo a sequence of breast cancer screening exams. We use age as a covariate in the estimation of screening sensitivity and the transition probability simultaneously, both from a frequentist point of view and within a Bayesian framework. We apply our method to the Health Insurance Plan of Greater New York study of female breast cancer and give age-dependent sensitivity and transition probability density estimates. The inferential methodology we develop is also applicable when analyzing studies of modalities for early detection of other types of progressive chronic diseases.

  2. ODVBA: optimally-discriminative voxel-based analysis.

    Science.gov (United States)

    Zhang, Tianhao; Davatzikos, Christos

    2011-08-01

    Gaussian smoothing of images prior to applying voxel-based statistics is an important step in voxel-based analysis and statistical parametric mapping (VBA-SPM) and is used to account for registration errors, to Gaussianize the data and to integrate imaging signals from a region around each voxel. However, it has also become a limitation of VBA-SPM based methods, since it is often chosen empirically and lacks spatial adaptivity to the shape and spatial extent of the region of interest, such as a region of atrophy or functional activity. In this paper, we propose a new framework, named optimally-discriminative voxel-based analysis (ODVBA), for determining the optimal spatially adaptive smoothing of images, followed by applying voxel-based group analysis. In ODVBA, nonnegative discriminative projection is applied regionally to get the direction that best discriminates between two groups, e.g., patients and controls; this direction is equivalent to local filtering by an optimal kernel whose coefficients define the optimally discriminative direction. By considering all the neighborhoods that contain a given voxel, we then compose this information to produce the statistic for each voxel. Finally, permutation tests are used to obtain a statistical parametric map of group differences. ODVBA has been evaluated using simulated data in which the ground truth is known and with data from an Alzheimer's disease (AD) study. The experimental results have shown that the proposed ODVBA can precisely describe the shape and location of structural abnormality.

  3. Reference dosimetry calculations for neutron capture therapy with comparison of analytical and voxel models.

    Science.gov (United States)

    Goorley, J T; Kiger, W S; Zamenhof, R G

    2002-02-01

    As clinical trials of Neutron Capture Therapy (NCT) are initiated in the U.S. and other countries, new treatment planning codes are being developed to calculate detailed dose distributions in patient-specific models. The thorough evaluation and comparison of treatment planning codes is a critical step toward the eventual standardization of dosimetry, which, in turn, is an essential element for the rational comparison of clinical results from different institutions. In this paper we report development of a reference suite of computational test problems for NCT dosimetry and discuss common issues encountered in these calculations to facilitate quantitative evaluations and comparisons of NCT treatment planning codes. Specifically, detailed depth-kerma rate curves were calculated using the Monte Carlo radiation transport code MCNP4B for four different representations of the modified Snyder head phantom, an analytic, multishell, ellipsoidal model, and voxel representations of this model with cubic voxel sizes of 16, 8, and 4 mm. Monoenergetic and monodirectional beams of 0.0253 eV, 1, 2, 10, 100, and 1000 keV neutrons, and 0.2, 0.5, 1, 2, 5, and 10 MeV photons were individually simulated to calculate kerma rates to a statistical uncertainty of neutron beam with a broad neutron spectrum, similar to epithermal beams currently used or proposed for NCT clinical trials, was computed for all models. The thermal neutron, fast neutron, and photon kerma rates calculated with the 4 and 8 mm voxel models were within 2% and 4%, respectively, of those calculated for the analytical model. The 16 mm voxel model produced unacceptably large discrepancies for all dose components. The effects from different kerma data sets and tissue compositions were evaluated. Updating the kerma data from ICRU 46 to ICRU 63 data produced less than 2% difference in kerma rate profiles. The depth-dose profile data, Monte Carlo code input, kerma factors, and model construction files are available

  4. Age-dependent effect of static magnetic field on brain tissue hydration.

    Science.gov (United States)

    Deghoyan, Anush; Nikoghosyan, Anna; Heqimyan, Armenuhi; Ayrapetyan, Sinerik

    2014-01-01

    Age-dependent effect of Static Magnetic Field (SMF) on rats in a condition of active and inactive Na(+)/K(+) pump was studied for comparison of brain tissues hydration state changes and magnetic sensitivity. Influence of 15 min 0, 2 Tesla (T) SMF on brain tissue hydration of three aged groups of male albino rats was studied. Tyrode's physiological solution and 10(-4) M ouabain was used for intraperitoneal injections. For animal immobilization, the liquid nitrogen was used and the definition of tissue water content was performed by tissue drying method. Initial water content in brain tissues of young animals is significantly higher than in those of adult and aged ones. SMF exposure leads to decrease of water content in brain tissues of young animals and increase in brain tissues of adult and aged ones. In case of ouabain-poisoned animals, SMF gives reversal effects on brain tissue's hydration both in young and aged animals, while no significant effect on adults is observed. It is suggested that initial state of tissue hydration could play a crucial role in animal age-dependent magnetic sensitivity and the main reason for this could be age-dependent dysfunction of Na(+)/K(+) pump.

  5. Maternal care, mother-offspring aggregation and age-dependent coadaptation in the European earwig.

    Science.gov (United States)

    Gómez, Y; Kölliker, M

    2013-09-01

    Benefits and costs of parental care are expected to change with offspring development and lead to age-dependent coadaptation expressed as phenotypic (behavioural) matches between offspring age and parental reproductive stage. Parents and offspring interact repeatedly over time for the provision of parental care. Their behaviours should be accordingly adjusted to each other dynamically and adaptively, and the phenotypic match between offspring age and parental stage should stabilize the repeated behavioural interactions. In the European earwig (Forficula auricularia), maternal care is beneficial for offspring survival, but not vital, allowing us to investigate the extent to which the stability of mother-offspring aggregation is shaped by age-dependent coadaptation. In this study, we experimentally cross-fostered nymphs of different age classes (younger or older) between females in early or late reproductive stage to disrupt age-dependent coadaptation, thereby generating female-nymph dyads that were phenotypically matched or mismatched. The results revealed a higher stability in aggregation during the first larval instar when care is most intense, a steeper decline in aggregation tendency over developmental time and a reduced developmental rate in matched compared with mismatched families. Furthermore, nymph survival was positively correlated with female-nymph aggregation stability during the early stages when maternal care is most prevalent. These results support the hypothesis that age-related phenotypically plastic coadaptation affects family dynamics and offspring developmental rate.

  6. Voxel-by-voxel analysis of brain SPECT perfusion in Fibromyalgia

    Science.gov (United States)

    Guedj, Eric; Taïeb, David; Cammilleri, Serge; Lussato, David; de Laforte, Catherine; Niboyet, Jean; Mundler, Olivier

    2007-02-01

    We evaluated brain perfusion SPECT at rest, without noxious stiumuli, in a homogeneous group of hyperalgesic FM patients. We performed a voxel-based analysis in comparison to a control group, matched for age and gender. Under such conditions, we made the assumption that significant cerebral perfusion abnormalities could be demonstrated, evidencing altered cerebral processing associated with spontaneous pain in FM patients. The secondary objective was to study the reversibility and the prognostic value of such possible perfusion abnormalities under specific treatment. Eighteen hyperalgesic FM women (mean age 48 yr; range 25-63 yr; ACR criteria) and 10 healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 ( ppain care unit. A second SPECT was performed a month later after specific treatment by Ketamine. Compared to control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. We also found that a medial frontal and anterior cingulate hypoperfusions were highly predictive (PPV=83%; NPV=91%) of non-response on Ketamine, and that only responders showed significant modification of brain perfusion, after treatment. In the present study performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective dimension. As current pharmacological and non-pharmacological therapies act differently on both components of pain, we hypothesize that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain-processing recovery under treatment.

  7. Voxel-by-voxel analysis of brain SPECT perfusion in Fibromyalgia

    Energy Technology Data Exchange (ETDEWEB)

    Guedj, Eric [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France)]. E-mail: eric.guedj@ap-hm.fr; Taieb, David [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Cammilleri, Serge [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Lussato, David [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Laforte, Catherine de [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France); Niboyet, Jean [Unite d' Etude et de Traitement de la Douleur, Clinique La Phoceanne, Marseille (France); Mundler, Olivier [Service Central de Biophysique et de Medecine Nucleaire, AP-HM Timone, Marseille (France)

    2007-02-01

    We evaluated brain perfusion SPECT at rest, without noxious stiumuli, in a homogeneous group of hyperalgesic FM patients. We performed a voxel-based analysis in comparison to a control group, matched for age and gender. Under such conditions, we made the assumption that significant cerebral perfusion abnormalities could be demonstrated, evidencing altered cerebral processing associated with spontaneous pain in FM patients. The secondary objective was to study the reversibility and the prognostic value of such possible perfusion abnormalities under specific treatment. Eighteen hyperalgesic FM women (mean age 48 yr; range 25-63 yr; ACR criteria) and 10 healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 (p<0.05, corrected for multiple comparisons). All brain SPECT were performed before any change was made in therapy in the pain care unit. A second SPECT was performed a month later after specific treatment by Ketamine. Compared to control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. We also found that a medial frontal and anterior cingulate hypoperfusions were highly predictive (PPV=83%; NPV=91%) of non-response on Ketamine, and that only responders showed significant modification of brain perfusion, after treatment. In the present study performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective dimension. As current pharmacological and non-pharmacological therapies act differently on both components of pain, we hypothesize that SPECT could be a valuable and readily available tool to guide individual therapeutic

  8. A comparative study on patient specific absolute dosimetry using slab phantom, acrylic body phantom and goat head phantom

    Directory of Open Access Journals (Sweden)

    Om Prakash Gurjar

    2015-01-01

    Full Text Available Purpose: To compare the results of patient specific absolute dosimetry using slab phantom, acrylic body phantom and goat head phantom. Methods: Fifteen intensity modulated radiotherapy (IMRT plans already planned on treatment planning system (TPS for head-and-neck cancer patients were exported on all three kinds of phantoms viz. slab phantom, acrylic body phantom and goat head phantom, and dose was calculated using anisotropic analytic algorithm (AAA. All the gantry angles were set to zero in case of slab phantom while set to as it is in actual plan in case of other two phantoms. All the plans were delivered by linear accelerator (LA and dose for each plan was measured by 0.13 cc ion chamber. The percentage (% variations between planned and measured doses were calculated and analyzed. Results: The mean % variations between planned and measured doses of all IMRT quality assurance (QA plans were as 0.65 (Standard deviation (SD: 0.38 with confidence limit (CL 1.39, 1.16 (SD: 0.61 with CL 2.36 and 2.40 (SD: 0.86 with CL 4.09 for slab phantom, acrylic head phantom and goat head phantom respectively. Conclusion: Higher dose variations found in case of real tissue phantom compare to results in case of slab and acrylic body phantoms. The algorithm AAA does not calculate doses in heterogeneous medium as accurate as it calculates in homogeneous medium. Therefore the patient specific absolute dosimetry should be done using heterogeneous phantom mimicking density wise as well as design wise to the actual human body.  

  9. Geometric features for voxel-based surface recognition

    OpenAIRE

    Yarotsky, Dmitry

    2017-01-01

    We introduce a library of geometric voxel features for CAD surface recognition/retrieval tasks. Our features include local versions of the intrinsic volumes (the usual 3D volume, surface area, integrated mean and Gaussian curvature) and a few closely related quantities. We also compute Haar wavelet and statistical distribution features by aggregating raw voxel features. We apply our features to object classification on the ESB data set and demonstrate accurate results with a small number of s...

  10. Phantom Dark Energy and its Cosmological Consequences

    CERN Document Server

    Dabrowski, Mariusz P

    2016-01-01

    I discuss the dark energy characterized by the violation of the null energy condition ($\\varrho + p \\geq 0$), dubbed phantom. Amazingly, it is admitted by the current astronomical data from supernovae. We discuss both classical and quantum cosmological models with phantom as a source of matter and present the phenomenon called phantom duality.

  11. Voxel-based texture analysis of the brain.

    Science.gov (United States)

    Maani, Rouzbeh; Yang, Yee Hong; Kalra, Sanjay

    2015-01-01

    This paper presents a novel voxel-based method for texture analysis of brain images. Texture analysis is a powerful quantitative approach for analyzing voxel intensities and their interrelationships, but has been thus far limited to analyzing regions of interest. The proposed method provides a 3D statistical map comparing texture features on a voxel-by-voxel basis. The validity of the method was examined on artificially generated effects as well as on real MRI data in Alzheimer's Disease (AD). The artificially generated effects included hyperintense and hypointense signals added to T1-weighted brain MRIs from 30 healthy subjects. The AD dataset included 30 patients with AD and 30 age/sex matched healthy control subjects. The proposed method detected artificial effects with high accuracy and revealed statistically significant differences between the AD and control groups. This paper extends the usage of texture analysis beyond the current region of interest analysis to voxel-by-voxel 3D statistical mapping and provides a hypothesis-free analysis tool to study cerebral pathology in neurological diseases.

  12. Mutant alpha-synuclein causes age-dependent neuropathology in monkey brain.

    Science.gov (United States)

    Yang, Weili; Wang, Guohao; Wang, Chuan-En; Guo, Xiangyu; Yin, Peng; Gao, Jinquan; Tu, Zhuchi; Wang, Zhengbo; Wu, Jing; Hu, Xintian; Li, Shihua; Li, Xiao-Jiang

    2015-05-27

    Parkinson's disease (PD) is an age-dependent neurodegenerative disease that often occurs in those over age 60. Although rodents and small animals have been used widely to model PD and investigate its pathology, their short life span makes it difficult to assess the aging-related pathology that is likely to occur in PD patient brains. Here, we used brain tissues from rhesus monkeys at 2-3, 7-8, and >15 years of age to examine the expression of Parkin, PINK1, and α-synuclein, which are known to cause PD via loss- or gain-of-function mechanisms. We found that α-synuclein is increased in the older monkey brains, whereas Parkin and PINK1 are decreased or remain unchanged. Because of the gain of toxicity of α-synuclein, we performed stereotaxic injection of lentiviral vectors expressing mutant α-synuclein (A53T) into the substantia nigra of monkeys and found that aging also increases the accumulation of A53T in neurites and its associated neuropathology. A53T also causes more extensive reactive astrocytes and axonal degeneration in monkey brain than in mouse brain. Using monkey brain tissues, we found that A53T interacts with neurofascin, an adhesion molecule involved in axon subcellular targeting and neurite outgrowth. Aged monkey brain tissues show an increased interaction of neurofascin with A53T. Overexpression of A53T causes neuritic toxicity in cultured neuronal cells, which can be attenuated by transfected neurofascin. These findings from nonhuman primate brains reveal age-dependent pathological and molecular changes that could contribute to the age-dependent neuropathology in PD.

  13. Fluctuation limit theorems for age-dependent critical binary branching systems

    Directory of Open Access Journals (Sweden)

    Murillo-Salas Antonio

    2011-03-01

    Full Text Available We consider an age-dependent branching particle system in ℝd, where the particles are subject to α-stable migration (0 < α ≤ 2, critical binary branching, and general (non-arithmetic lifetimes distribution. The population starts off from a Poisson random field in ℝd with Lebesgue intensity. We prove functional central limit theorems and strong laws of large numbers under two rescalings: high particle density, and a space-time rescaling that preserves the migration distribution. Properties of the limit processes such as Markov property, almost sure continuity of paths and generalized Langevin equation, are also investigated.

  14. Optimal control of an influenza model with seasonal forcing and age-dependent transmission rates.

    Science.gov (United States)

    Lee, Jeehyun; Kim, Jungeun; Kwon, Hee-Dae

    2013-01-21

    This study considers an optimal intervention strategy for influenza outbreaks. Variations in the SEIAR model are considered to include seasonal forcing and age structure, and control strategies include vaccination, antiviral treatment, and social distancing such as school closures. We formulate an optimal control problem by minimizing the incidence of influenza outbreaks while considering intervention costs. We examine the effects of delays in vaccine production, seasonal forcing, and age-dependent transmission rates on the optimal control and suggest some optimal strategies through numerical simulations.

  15. Age-Dependent Cortical Thinning of Peripheral Visual Field Representations in Primary Visual Cortex.

    Science.gov (United States)

    Griffis, Joseph C; Burge, Wesley K; Visscher, Kristina M

    2016-01-01

    The cerebral cortex changes throughout the lifespan, and the cortical gray matter in many brain regions becomes thinner with advancing age. Effects of aging on cortical thickness (CT) have been observed in many brain regions, including areas involved in basic perceptual functions such as processing visual inputs. An important property of early visual cortices is their topographic organization-the cortical structure of early visual areas forms a topographic map of retinal inputs. Primary visual cortex (V1) is considered to be the most basic cortical area in the visual processing hierarchy, and is topographically organized from posterior (central visual representation) to anterior (peripheral visual representation) along the calcarine sulcus. Some studies have reported strong age-dependent cortical thinning in portions of V1 that likely correspond to peripheral visual representations, while there is less evidence of substantial cortical thinning in central V1. However, the effect of aging on CT in V1 as a function of its topography has not been directly investigated. To address this gap in the literature, we estimated the CT of different eccentricity sectors in V1 using T1-weighted MRI scans acquired from groups of healthy younger and older adults, and then assessed whether between-group differences in V1 CT depended on cortical eccentricity. These analyses revealed age-dependent cortical thinning specific to peripheral visual field representations in anterior portions of V1, but did not provide evidence for age-dependent cortical thinning in other portions of V1. Additional analyses found similar effects when analyses were restricted to the gyral crown, sulcul depth and sulcul wall, indicating that these effects are not likely due to differences in gyral/sulcul contributions to our regions of interest (ROI). Importantly, this finding indicates that age-dependent changes in cortical structure may differ among functionally distinct zones within larger canonical

  16. Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Na, Yong Hum; Xu, X George [Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Zhang Binquan; Zhang Juying; Caracappa, Peter F, E-mail: xug2@rpi.ed [Nuclear Engineering and Engineering Physics, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2010-07-07

    Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999-2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals' size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms-modeled entirely in mesh surfaces-of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte

  17. Laser-induced forward transfer (LIFT) of congruent voxels

    Energy Technology Data Exchange (ETDEWEB)

    Piqué, Alberto, E-mail: pique@nrl.navy.mil [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Breckenfeld, Eric [National Research Council Fellow at the Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-06-30

    Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D

  18. Construction of hybrid Chinese reference adult phantoms and estimation of dose conversion coefficients for muons.

    Science.gov (United States)

    Dong, Liang; Li, Taosheng; Liu, Chunyu

    2015-04-01

    A set of fluence-to-effective dose conversion coefficients of external exposure to muons were investigated for Chinese hybrid phantom references, which include both male and female. Both polygon meshes and Non-Uniform Rational B-Spline (NURBS) surfaces were used to descried the boundary of the organs and tissues in these phantoms. The 3D-DOCTOR and Rhinoceros software were used to polygonise the colour slice images and generate the NURBS surfaces, respectively. The voxelisation is completed using the BINVOX software and the assembly finished by using MATLAB codes. The voxel resolutions were selected to be 0.22 × 0.22 × 0.22 cm(3) and 0.2 × 0.2 × 0.2 cm(3) for male and female phantoms, respectively. All parts of the final phantoms were matched to their reference organ masses within a tolerance of ±5%. The conversion coefficients for negative and positive muons were calculated with the FLUKA transport code. There were 21 external monoenergetic beams ranging from 0.01 GeV to 100 TeV in 5 different geometrical conditions of irradiation.

  19. Specific absorbed fractions of electrons and photons for Rad-HUMAN phantom using Monte Carlo method

    Institute of Scientific and Technical Information of China (English)

    WANG Wen; CHENG Meng-Yun; LONG Peng-Cheng; HU Li-Qin

    2015-01-01

    The specific absorbed fractions (SAF) for self-and cross-irradiation are effective tools for the internal dose estimation of inhalation and ingestion intakes of radionuclides.A set of SAFs of photons and electrons were calculated using the Rad-HUMAN phantom,which is a computational voxel phantom of a Chinese adult female that was created using the color photographic image of the Chinese Visible Human (CVH) data set by the FDS Team.The model can represent most Chinese adult female anatomical characteristics and can be taken as an individual phantom to investigate the difference of internal dose with Caucasians.In this study,the emission of mono-energetic photons and electrons of 10 keV to 4 MeV energy were calculated using the Monte Carlo particle transport calculation code MCNP.Results were compared with the values from ICRP reference and ORNL models.The results showed that SAF from the Rad-HUMAN have similar trends but are larger than those from the other two models.The differences were due to the racial and anatomical differences in organ mass and inter-organ distance.The SAFs based on the Rad-HUMAN phantom provide an accurate and reliable data for internal radiation dose calculations for Chinese females.

  20. Complex Lagrangians and phantom cosmology

    CERN Document Server

    Andrianov, A A; Kamenshchik, A Yu

    2006-01-01

    Motivated by the generalization of quantum theory for the case of non-Hermitian Hamiltonians with PT symmetry, we show how a classical cosmological model describes a smooth transition from ordinary dark energy to the phantom one. The model is based on a classical complex Lagrangian of a scalar field. Specific symmetry properties analogous to PT in non-Hermitian quantum mechanics lead to purely real equation of motion.

  1. Age-Dependent Differences in Systemic and Cell-Autonomous Immunity to L. monocytogenes

    Directory of Open Access Journals (Sweden)

    Ashley M. Sherrid

    2013-01-01

    Full Text Available Host defense against infection can broadly be categorized into systemic immunity and cell-autonomous immunity. Systemic immunity is crucial for all multicellular organisms, increasing in importance with increasing cellular complexity of the host. The systemic immune response to Listeria monocytogenes has been studied extensively in murine models; however, the clinical applicability of these findings to the human newborn remains incompletely understood. Furthermore, the ability to control infection at the level of an individual cell, known as “cell-autonomous immunity,” appears most relevant following infection with L. monocytogenes; as the main target, the monocyte is centrally important to innate as well as adaptive systemic immunity to listeriosis. We thus suggest that the overall increased risk to suffer and die from L. monocytogenes infection in the newborn period is a direct consequence of age-dependent differences in cell-autonomous immunity of the monocyte to L. monocytogenes. We here review what is known about age-dependent differences in systemic innate and adaptive as well as cell-autonomous immunity to infection with Listeria monocytogenes.

  2. Age-Dependent Increase of Absence Seizures and Intrinsic Frequency Dynamics of Sleep Spindles in Rats

    Directory of Open Access Journals (Sweden)

    Evgenia Sitnikova

    2014-01-01

    Full Text Available The risk of neurological diseases increases with age. In WAG/Rij rat model of absence epilepsy, the incidence of epileptic spike-wave discharges is known to be elevated with age. Considering close relationship between epileptic spike-wave discharges and physiologic sleep spindles, it was assumed that age-dependent increase of epileptic activity may affect time-frequency characteristics of sleep spindles. In order to examine this hypothesis, electroencephalograms (EEG were recorded in WAG/Rij rats successively at the ages 5, 7, and 9 months. Spike-wave discharges and sleep spindles were detected in frontal EEG channel. Sleep spindles were identified automatically using wavelet-based algorithm. Instantaneous (localized in time frequency of sleep spindles was determined using continuous wavelet transform of EEG signal, and intraspindle frequency dynamics were further examined. It was found that in 5-months-old rats epileptic activity has not fully developed (preclinical stage and sleep spindles demonstrated an increase of instantaneous frequency from beginning to the end. At the age of 7 and 9 months, when animals developed matured and longer epileptic discharges (symptomatic stage, their sleep spindles did not display changes of intrinsic frequency. The present data suggest that age-dependent increase of epileptic activity in WAG/Rij rats affects intrinsic dynamics of sleep spindle frequency.

  3. Skeletal dosimetry for external exposures to photons based on {mu}CT images of spongiosa: Consideration of voxel resolution, cluster size, and medullary bone surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, R.; Khoury, H. J.; Vieira, J. W.; Brown, K. A. Robson [Departamento de Energia Nuclear, Universidade Federal de Pernambuco, Avenida Professor Luiz Freire 1000, Cidade Universitaria, CEP 50740-540, Recife, Pernambuco (Brazil); Centro Federal de Educacao Tecnologica de Pernambuco, Avenida Professor Luiz Freire 500, CEP 50740-540, Recife, Pernambuco, Brazil and Escola Politecnica, UPE, Rua Benfica 455, CEP 50751-460, Recife, Pernambuco (Brazil); Imaging Laboratory, Department of Archaeology and Anthropology, University of Bristol, 43 Woodland Road, Bristol BS8 1UU (United Kingdom)

    2009-11-15

    Skeletal dosimetry based on {mu}CT images of trabecular bone has recently been introduced to calculate the red bone marrow (RBM) and the bone surface cell (BSC) equivalent doses in human phantoms for external exposure to photons. In order to use the {mu}CT images for skeletal dosimetry, spongiosa voxels in the skeletons were replaced at run time by so-called micromatrices, which have exactly the size of a spongiosa voxel and contain segmented trabecular bone and marrow microvoxels. A cluster (=parallelepiped) of 2x2x2=8 micromatrices was used systematically and periodically throughout the spongiosa volume during the radiation transport calculation. Systematic means that when a particle leaves a spongiosa voxel to enter into a neighboring spongiosa voxel, then the next micromatrix in the cluster will be used. Periodical means that if the particle travels through more than two spongiosa voxels in a row, then the cluster will be repeated. Based on the bone samples available at the time, clusters of up to 3x3x3=27 micromatrices were studied. While for a given trabecular bone volume fraction the whole-body RBM equivalent dose showed converging results for cluster sizes between 8 and 27 micromatrices, this was not the case for the BSC equivalent dose. The BSC equivalent dose seemed to be very sensitive to the number, form, and thickness of the trabeculae. In addition, the cluster size and/or the microvoxel resolution were considered to be possible causes for the differences observed. In order to resolve this problem, this study used a bone sample large enough to extract clusters containing up to 8x8x8=512 micromatrices and which was scanned with two different voxel resolutions. Taking into account a recent proposal, this investigation also calculated the BSC equivalent dose on medullary surfaces of cortical bone in the arm and leg bones. The results showed (1) that different voxel resolutions have no effect on the RBM equivalent dose but do influence the BSC equivalent

  4. Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms

    Science.gov (United States)

    Hum Na, Yong; Zhang, Binquan; Zhang, Juying; Caracappa, Peter F.; Xu, X. George

    2010-07-01

    Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999-2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals' size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms—modeled entirely in mesh surfaces—of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte

  5. Depth dose distribution study within a phantom torso after irradiation with a simulated Solar Particle Event at NSRL

    Science.gov (United States)

    Berger, Thomas; Matthiä, Daniel; Koerner, Christine; George, Kerry; Rhone, Jordan; Cucinotta, Francis A.; Reitz, Guenther

    benchmark computational radiation transport models in a radiation field of interest. The presentation will give first results of the physical dose distribution, the comparison with GEANT4 computer simulations, based on a Voxel model of the phantom, and a comparison with the data from the chromosome aberration study. The help and support of Adam Russek and Michael Sivertz of the NASA Space Radiation Laboratory (NSRL), Brookhaven, USA during the setup and the irradiation of the phantom are highly appreciated. The Voxel model describing the human phantom used for the GEANT4 simulations was kindly provided by Monika Puchalska (CHALMERS, Gothenburg, Sweden).

  6. Voxel inversion of airborne electromagnetic data for improved model integration

    Science.gov (United States)

    Fiandaca, Gianluca; Auken, Esben; Kirkegaard, Casper; Vest Christiansen, Anders

    2014-05-01

    Inversion of electromagnetic data has migrated from single site interpretations to inversions including entire surveys using spatial constraints to obtain geologically reasonable results. Though, the model space is usually linked to the actual observation points. For airborne electromagnetic (AEM) surveys the spatial discretization of the model space reflects the flight lines. On the contrary, geological and groundwater models most often refer to a regular voxel grid, not correlated to the geophysical model space, and the geophysical information has to be relocated for integration in (hydro)geological models. We have developed a new geophysical inversion algorithm working directly in a voxel grid disconnected from the actual measuring points, which then allows for informing directly geological/hydrogeological models. The new voxel model space defines the soil properties (like resistivity) on a set of nodes, and the distribution of the soil properties is computed everywhere by means of an interpolation function (e.g. inverse distance or kriging). Given this definition of the voxel model space, the 1D forward responses of the AEM data are computed as follows: 1) a 1D model subdivision, in terms of model thicknesses, is defined for each 1D data set, creating "virtual" layers. 2) the "virtual" 1D models at the sounding positions are finalized by interpolating the soil properties (the resistivity) in the center of the "virtual" layers. 3) the forward response is computed in 1D for each "virtual" model. We tested the new inversion scheme on an AEM survey carried out with the SkyTEM system close to Odder, in Denmark. The survey comprises 106054 dual mode AEM soundings, and covers an area of approximately 13 km X 16 km. The voxel inversion was carried out on a structured grid of 260 X 325 X 29 xyz nodes (50 m xy spacing), for a total of 2450500 inversion parameters. A classical spatially constrained inversion (SCI) was carried out on the same data set, using 106054

  7. Laser-induced forward transfer (LIFT) of congruent voxels

    Science.gov (United States)

    Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C. Y.; Beniam, Iyoel; Breckenfeld, Eric

    2016-06-01

    Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D and 3D microstructures by adjusting the viscosity of the nano-suspension and laser transfer parameters.

  8. Dosimetric evaluation of intrafractional tumor motion by means of a robot driven phantom

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Anne; Wilbert, Juergen; Flentje, Michael [Department of Radiation Oncology, University of Wuerzburg, 97080 Wuerzburg (Germany)

    2011-10-15

    Purpose: The aim of the work was to investigate the influence of intrafractional tumor motion to the accumulated (absorbed) dose. The accumulated dose was determined by means of calculations and measurements with a robot driven motion phantom. Methods: Different motion scenarios and compensation techniques were realized in a phantom study to investigate the influence of motion on image acquisition, dose calculation, and dose measurement. The influence of motion on the accumulated dose was calculated by employing two methods (a model based and a voxel based method). Results: Tumor motion resulted in a blurring of steep dose gradients and a reduction of dose at the periphery of the target. A systematic variation of motion parameters allowed the determination of the main influence parameters on the accumulated dose. The key parameters with the greatest influence on dose were the mean amplitude and the pattern of motion. Investigations on necessary safety margins to compensate for dose reduction have shown that smaller safety margins are sufficient, if the developed concept with optimized margins (OPT concept) was used instead of the standard internal target volume (ITV) concept. Both calculation methods were a reasonable approximation of the measured dose with the voxel based method being in better agreement with the measurements. Conclusions: Further evaluation of available systems and algorithms for dose accumulation are needed to create guidelines for the verification of the accumulated dose.

  9. Age-dependent NOC/oFQ contribution to impaired hypotensive cerebral hemodynamics after brain injury.

    Science.gov (United States)

    Armstead, William M

    2002-10-01

    Previous studies have observed that the newly described opioid, nociceptin/orphanin FQ (NOC/oFQ), contributed to age dependent reductions in cerebral blood flow (CBF) and pial artery diameter after fluid percussion brain injury (FPI). Unrelated studies have noted a similar age dependency in impaired hypotensive cerebral autoregulation after FPI. This study was designed to compare the role of NOC/oFQ in impaired hypotensive cerebral autoregulation after FPI in newborn and juvenile pigs equipped with a closed cranial window. Ten minutes of hemorrhagic hypotension (10-15 mL blood/kg) decreased mean arterial blood pressure uniformly in both groups ( approximately 44%). In the newborn, hypotensive pial artery dilation was blunted within 1 h of FPI but partially protected by pretreatment with the NOC/oFQ antagonist, [F/G] NOC/oFQ (1-13) NH(2) (1 mg/kg, i.v.) (34 +/- 1 vs. 8 +/- 1 vs. 20 +/- 2% for sham control, FPI, and FPI-[F/G] NOC/oFQ (1-13) NH(2), respectively). CBF was reduced during normotension by FPI, further reduced by hypotension, but both were partially protected by this antagonist in the newborn (63 +/- 4, 34 +/- 2, and 20 +/- 2 vs. 65 +/- 4, 47 +/- 2, and 29 +/- 2 mL/min.100 g for normotension, normotension-FPI and hypotension-FPI in the absence and presence of [F/G] NOC/oFQ (1-13) NH(2), respectively). In contrast, blunted hypotensive pial artery dilation was protected significantly less by this NOC/oFQ antagonist in the juvenile (32 +/- 2 vs. 7 +/- 2 vs. 13 +/- 2% for sham control, FPI and FPI-NOC/oFQ antagonist, respectively). Similarly, [F/G] NOC/oFQ (1-13) NH(2) had less protective effect on normotensive and hypotensive CBF values post FPI in the juvenile. These data indicate that NOC/oFQ contributes to impaired hypotensive cerebral hemodynamics following brain injury in an age-dependent manner.

  10. The effect of anatomical modeling on space radiation dose estimates: a comparison of doses for NASA phantoms and the 5th, 50th, and 95th percentile male and female astronauts.

    Science.gov (United States)

    Bahadori, Amir A; Van Baalen, Mary; Shavers, Mark R; Dodge, Charles; Semones, Edward J; Bolch, Wesley E

    2011-03-21

    The National Aeronautics and Space Administration (NASA) performs organ dosimetry and risk assessment for astronauts using model-normalized measurements of the radiation fields encountered in space. To determine the radiation fields in an organ or tissue of interest, particle transport calculations are performed using self-shielding distributions generated with the computer program CAMERA to represent the human body. CAMERA mathematically traces linear rays (or path lengths) through the computerized anatomical man (CAM) phantom, a computational stylized model developed in the early 1970s with organ and body profiles modeled using solid shapes and scaled to represent the body morphometry of the 1950 50th percentile (PCTL) Air Force male. With the increasing use of voxel phantoms in medical and health physics, a conversion from a mathematical-based to a voxel-based ray-tracing algorithm is warranted. In this study, the voxel-based ray tracer (VoBRaT) is introduced to ray trace voxel phantoms using a modified version of the algorithm first proposed by Siddon (1985 Med. Phys. 12 252-5). After validation, VoBRAT is used to evaluate variations in body self-shielding distributions for NASA phantoms and six University of Florida (UF) hybrid phantoms, scaled to represent the 5th, 50th, and 95th PCTL male and female astronaut body morphometries, which have changed considerably since the inception of CAM. These body self-shielding distributions are used to generate organ dose equivalents and effective doses for five commonly evaluated space radiation environments. It is found that dosimetric differences among the phantoms are greatest for soft radiation spectra and light vehicular shielding.

  11. White LED compared with other light sources: age-dependent photobiological effects and parameters for evaluation.

    Science.gov (United States)

    Rebec, Katja Malovrh; Klanjšek-Gunde, Marta; Bizjak, Grega; Kobav, Matej B

    2015-01-01

    Ergonomic science at work and living places should appraise human factors concerning the photobiological effects of lighting. Thorough knowledge on this subject has been gained in the past; however, few attempts have been made to propose suitable evaluation parameters. The blue light hazard and its influence on melatonin secretion in age-dependent observers is considered in this paper and parameters for its evaluation are proposed. New parameters were applied to analyse the effects of white light-emitting diode (LED) light sources and to compare them with the currently applied light sources. The photobiological effects of light sources with the same illuminance but different spectral power distribution were determined for healthy 4-76-year-old observers. The suitability of new parameters is discussed. Correlated colour temperature, the only parameter currently used to assess photobiological effects, is evaluated and compared to new parameters.

  12. Age-dependent branching processes for surveillance of vaccine-preventable diseases with incubation period

    Directory of Open Access Journals (Sweden)

    Marusia N Bojkova

    2010-10-01

    Full Text Available The purpose of this paper is to review the recent results of the authors in the area of infectious disease modelling by means of branching stochastic processes. This is a new approach involving age-dependent branching models, which turned out to be more appropriate and flexible for describing the spread of an infection in a given population, than discrete time ones. Concretely, Bellman-Harris and Sevast’yanov’s branching processes are investigated. It is justified that the proposed models are proper candidates as models of infectious diseases with incubation period like measles, mumps, avian flu, etc. It is worth to notice that in general the developed methodology is applicable to the diseases that follow the so-called SIR (susceptible- infected-removed scheme in terms of epidemiological models. Two policies of extra-vaccination level are proposed and compared on the ground of simulation examples.

  13. Age-dependent accumulation of (137)Cs by pike Esox lucius in the Yenisei River.

    Science.gov (United States)

    Zotina, T A; Trofimova, E A; Dementyev, D V; Bolsunovsky, A Ya

    2016-05-01

    Age-dependent accumulation of (137)Cs in the muscles and bodies of the pike Esox lucius (aged two to seven years) inhabiting a section of the Yenisei River polluted with artificial radionuclides has been studied. The content of (137)Cs in muscles varied from 0.5 to 7.0 Bq/kg of fresh weight. The maximum content of the radionuclide has been found in juveniles. The content of (137)Cs in pike muscles and body decreased considerably with age. The high content of (137)Cs in the muscles of juveniles is probably a consequence of their higher intensity of feeding as compared to older individuals, which is due to the intense growth of juveniles.

  14. Rapid registration of multimodal images using a reduced number of voxels

    Science.gov (United States)

    Huang, Xishi; Hill, Nicholas A.; Ren, Jing; Peters, Terry M.

    2006-03-01

    Rapid registration of multimodal cardiac images can improve image-guided cardiac surgeries and cardiac disease diagnosis. While mutual information (MI) is arguably the most suitable registration technique, this method is too slow to converge for real time cardiac image registration; moreover, correct registration may not coincide with a global or even local maximum of MI. These limitations become quite evident when registering three-dimensional (3D) ultrasound (US) images and dynamic 3D magnetic resonance (MR) images of the beating heart. To overcome these issues, we present a registration method that uses a reduced number of voxels, while retaining adequate registration accuracy. Prior to registration we preprocess the images such that only the most representative anatomical features are depicted. By selecting samples from preprocessed images, our method dramatically speeds up the registration process, as well as ensuring correct registration. We validated this registration method for registering dynamic US and MR images of the beating heart of a volunteer. Experimental results on in vivo cardiac images demonstrate significant improvements in registration speed without compromising registration accuracy. A second validation study was performed registering US and computed tomography (CT) images of a rib cage phantom. Two similarity metrics, MI and normalized crosscorrelation (NCC) were used to register the image sets. Experimental results on the rib cage phantom indicate that our method can achieve adequate registration accuracy within 10% of the computation time of conventional registration methods. We believe this method has the potential to facilitate intra-operative image fusion for minimally invasive cardio-thoracic surgical navigation.

  15. Fluoxetine exerts age-dependent effects on behavior and amygdala neuroplasticity in the rat.

    Directory of Open Access Journals (Sweden)

    Judith R Homberg

    Full Text Available The selective serotonin reuptake inhibitor (SSRI Prozac® (fluoxetine is the only registered antidepressant to treat depression in children and adolescents. Yet, while the safety of SSRIs has been well established in adults, serotonin exerts neurotrophic actions in the developing brain and thereby may have harmful effects in adolescents. Here we treated adolescent and adult rats chronically with fluoxetine (12 mg/kg at postnatal day (PND 25 to 46 and from PND 67 to 88, respectively, and tested the animals 7-14 days after the last injection when (norfluoxetine in blood plasma had been washed out, as determined by HPLC. Plasma (norfluoxetine levels were also measured 5 hrs after the last fluoxetine injection, and matched clinical levels. Adolescent rats displayed increased behavioral despair in the forced swim test, which was not seen in adult fluoxetine treated rats. In addition, beneficial effects of fluoxetine on wakefulness as measured by electroencephalography in adults was not seen in adolescent rats, and age-dependent effects on the acoustic startle response and prepulse inhibition were observed. On the other hand, adolescent rats showed resilience to the anorexic effects of fluoxetine. Exploratory behavior in the open field test was not affected by fluoxetine treatment, but anxiety levels in the elevated plus maze test were increased in both adolescent and adult fluoxetine treated rats. Finally, in the amygdala, but not the dorsal raphe nucleus and medial prefrontal cortex, the number of PSA-NCAM (marker for synaptic remodeling immunoreactive neurons was increased in adolescent rats, and decreased in adult rats, as a consequence of chronic fluoxetine treatment. No fluoxetine-induced changes in 5-HT(1A receptor immunoreactivity were observed. In conclusion, we show that fluoxetine exerts both harmful and beneficial age-dependent effects on depressive behavior, body weight and wakefulness, which may relate, in part, to differential

  16. Age dependency of serum insulin - like growth factor (IGF-1 in healthy Turkish adolescents and adults.

    Directory of Open Access Journals (Sweden)

    Tiryakioaylu O

    2003-12-01

    Full Text Available BACKGROUND: Serum levels of insulin-like growth factor-1 (IGF-1 reflect endogenous growth hormone (GH secretion in healthy subjects. Measurements of IGF-1 are useful for diagnosis and follow-up of patients with acromegaly and the diagnosis of GH deficiency in children. AIMS: To assess age dependency and normal ranges of serum IGF-1 levels in healthy Turkish population. SETTING AND DESIGN: We therefore studied 272 healthy adolescents and adults between 15-75 years of age. None had diabetes or other endocrine disease or had received estrogen therapy. MATERIAL AND METHODS: Height, weight, body mass index (BMI and waist-hip ratio were measured in all subjects. Serum samples were obtained during morning hours and IGF-1 was measured by radioimmunoassay. STATISTICAL ANALYSIS: The age-dependent reference range for serum IGF-1 concentrations was calculated by simple least linear regression analysis: the regression line represents the means with 95 percent confidence intervals. Correlation analysis was also done. RESULTS: Ageing was negatively related to serum levels of IGF-1 (P= 0.0001, r=-0.931 with a mean decrease (youngest vs. oldest. IGF-1 levels increased during adolescence, with the highest mean values during puberty. After puberty, a subsequent decline in serum levels of IGF-1 was apparent. There were also a significant difference according to gender; females had significantly higher levels (357.909+/-219.167 mg/L than males (307.962+/-198.41 mg/L (P=0.012. IGF-1 levels were correlated with body height (P=0.001, r=0.223, body weight (P=0.002,r=-0.188 and BMI (P=0.039, r=0.128. CONCLUSION: IGF-1 serum levels increase in adolescents with a peak in puberty, whereafter IGF-1 levels return to prepubertal levels.

  17. Age-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters

    Directory of Open Access Journals (Sweden)

    Seok Kyu eKang

    2015-05-01

    Full Text Available Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB, with NKCC1 antagonist bumetanide (BTN as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in postnatal day 7, 10 and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy.

  18. Transient Elastography-Based Liver Stiffness Age-Dependently Increases in Children

    Science.gov (United States)

    Tokuhara, Daisuke; Cho, Yuki; Shintaku, Haruo

    2016-01-01

    Background and Aims Pediatric use of liver transient elastography (TE) is attractive for its non-invasiveness, but reference values have not been established. We aimed to determine reference values for TE in children. Methods In pediatric patients (1 to 18 years), TE (FibroScan®) with an M probe was used for both liver stiffness measurement (LSM) and measurement of hepatic fat deposition by using a controlled attenuation parameter (CAP). The patients were divided into three relevant age groups: preschoolers (1 to 5 years), elementary school children (6 to 11 years), and adolescents (12 to 18 years). Overweight or obese patients or those with known liver disease, elevated serum liver enzymes, or hepatic echogenic abnormality were excluded from the study. Results Among 139 children, 123 (88.5%; 62 male; median age, 11.7 years; age range, 1.3 to 17.2 years) were successfully subjected to M-probe TE without anesthesia. Median LSM increased with age: it was 3.4 kPa (2.3 to 4.6 kPa, 5th to 95th percentiles) at ages 1 to 5 years; 3.8 (2.5 to 6.1) kPa at ages 6 to 11; and 4.1 (3.3 to 7.9) kPa at ages 12 to 18 (P = 0.001). Median CAP was not age dependent: it was 183 (112 to 242) for ages 1 to 18 years. Conclusions M-probe TE is suitable in a wide age range of children from age 1 year up. In children without evidence of liver disease, LSM has an age-dependent increase, whereas CAP does not differ between ages 1 and 18. PMID:27861607

  19. Change in Image Quality According to the 3D Locations of a CBCT Phantom.

    Directory of Open Access Journals (Sweden)

    Jae Joon Hwang

    Full Text Available A patient's position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV. To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR, and the 10% point of the modulation transfer function (MTF10% of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR, 70.49% (homogeneity, and 13.64% (MTF10%. Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important.

  20. A Morphological Approach to the Voxelization of Solids

    DEFF Research Database (Denmark)

    Bærentzen, Jakob Andreas; Sramek, Milos; Christensen, Niels Jørgen

    2000-01-01

    In this paper we present a new, morphological criterion for determining whether a geometric solid is suitable for voxelization at a given resolution. The criterion embodies two conditions, namely that the curvature of the solid must be bounded and the critical points of the distance field must...... be at a certain distance from the boundary of the solid. For solids that fulfill this criterion, we present an analytic and an empirical bound for the trilinear reconstruction error. Additionally, we give a theoretical argument as to why the distance field approach to voxelization is more sound than...

  1. An Improved Optimization Method for the Relevance Voxel Machine

    DEFF Research Database (Denmark)

    Ganz, Melanie; Sabuncu, M. R.; Van Leemput, Koen

    2013-01-01

    In this paper, we will re-visit the Relevance Voxel Machine (RVoxM), a recently developed sparse Bayesian framework used for predicting biological markers, e.g., presence of disease, from high-dimensional image data, e.g., brain MRI volumes. The proposed improvement, called IRVoxM, mitigates...... the shortcomings of the greedy optimization scheme of the original RVoxM algorithm by exploiting the form of the marginal likelihood function. In addition, it allows voxels to be added and deleted from the model during the optimization. In our experiments we show that IRVoxM outperforms RVoxM on synthetic data...

  2. Monte Carlo simulation of secondary radiation exposure from high-energy photon therapy using an anthropomorphic phantom.

    Science.gov (United States)

    Frankl, Matthias; Macián-Juan, Rafael

    2016-03-01

    The development of intensity-modulated radiotherapy treatments delivering large amounts of monitor units (MUs) recently raised concern about higher risks for secondary malignancies. In this study, optimised combinations of several variance reduction techniques (VRTs) have been implemented in order to achieve a high precision in Monte Carlo (MC) radiation transport simulations and the calculation of in- and out-of-field photon and neutron dose-equivalent distributions in an anthropomorphic phantom using MCNPX, v.2.7. The computer model included a Varian Clinac 2100C treatment head and a high-resolution head phantom. By means of the applied VRTs, a relative uncertainty for the photon dose-equivalent distribution of 8 MeV, has been calculated. Relative uncertainty, calculated for each voxel, could be kept below 5 % in average over all voxels of the phantom. Thus, a very detailed neutron dose distribution could be obtained. The achieved precision now allows a far better estimation of both photon and especially neutron doses out-of-field, where neutrons can become the predominant component of secondary radiation.

  3. Exact solution of phantom dark energy model

    Institute of Scientific and Technical Information of China (English)

    Wang Wen-Fu; Shui Zheng-Wei; Tang Bin

    2010-01-01

    We investigate the phantom dark energy model derived from the scalar field with a negative kinetic term. By assuming a particular relation between the time derivative of the phantom field and the Hubble function, an exact solution of the model is constructed. Absence of the 'big rip' singularity is shown explicitly. We then derive special features of phantom dark energy model and show that its predictions are consistent with all astrophysical observations.

  4. Neutron dosimetry in solid water phantom

    Energy Technology Data Exchange (ETDEWEB)

    Benites-Rengifo, Jorge Luis, E-mail: jlbenitesr@prodigy.net.mx [Centro Estatal de Cancerologia de Nayarit, Calzada de la Cruz 118 Sur, Tepic Nayarit, Mexico and Instituto Tecnico Superior de Radiologia, ITEC, Calle Leon 129, Tepic Nayarit (Mexico); Vega-Carrillo, Hector Rene, E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. postal 336, 98000, Zacatecas, Zac. (Mexico)

    2014-11-07

    The neutron spectra, the Kerma and the absorbed dose due to neutrons were estimated along the incoming beam in a solid water phantom. Calculations were carried out with the MCNP5 code, where the bunker, the phantom and the model of the15 MV LINAC head were modeled. As the incoming beam goes into the phantom the neutron spectrum is modified and the dosimetric values are reduced.

  5. Do Phantom Cuntz-Krieger Algebras Exist?

    DEFF Research Database (Denmark)

    Arklint, Sara E.

    2013-01-01

    If phantom Cuntz-Krieger algebras do not exist, then purely infinite Cuntz-Krieger algebras can be characterized by outer properties. In this survey paper, a summary of the known results on non-existence of phantom Cuntz-Krieger algebras is given......If phantom Cuntz-Krieger algebras do not exist, then purely infinite Cuntz-Krieger algebras can be characterized by outer properties. In this survey paper, a summary of the known results on non-existence of phantom Cuntz-Krieger algebras is given...

  6. Galileons, phantom and the Fate of Universe

    CERN Document Server

    Shahalam, M; Myrzakulov, R

    2016-01-01

    In this paper we study cosmological dynamics of phantom as well as non-phantom fields with linear potential in presence of Galileon correction $(\\partial_\\mu\\phi \\partial^\\mu\\phi) \\Box \\phi$. We show that the Big Crunch singularity is delayed compared to the standard case; the delay crucially depends upon the strength of Galileon correction. As for the phantom Galileon, $\\rho_{\\phi}$ is shown to grow more slowly compared to the standard phantom delaying the approach to singularity. In case, $V\\sim \\phi^n, n>4$, Big Rip is also delayed, similar phenomenon is shown to take place for potentials steeper than the exponential.

  7. Monte Carlo fast dose calculator for proton radiotherapy: application to a voxelized geometry representing a patient with prostate cancer.

    Science.gov (United States)

    Yepes, Pablo; Randeniya, Sharmalee; Taddei, Phillip J; Newhauser, Wayne D

    2009-01-07

    The Monte Carlo method is used to provide accurate dose estimates in proton radiation therapy research. While it is more accurate than commonly used analytical dose calculations, it is computationally intense. The aim of this work was to characterize for a clinical setup the fast dose calculator (FDC), a Monte Carlo track-repeating algorithm based on GEANT4. FDC was developed to increase computation speed without diminishing dosimetric accuracy. The algorithm used a database of proton trajectories in water to calculate the dose of protons in heterogeneous media. The extrapolation from water to 41 materials was achieved by scaling the proton range and the scattering angles. The scaling parameters were obtained by comparing GEANT4 dose distributions with those calculated with FDC for homogeneous phantoms. The FDC algorithm was tested by comparing dose distributions in a voxelized prostate cancer patient as calculated with well-known Monte Carlo codes (GEANT4 and MCNPX). The track-repeating approach reduced the CPU time required for a complete dose calculation in a voxelized patient anatomy by more than two orders of magnitude, while on average reproducing the results from the Monte Carlo predictions within 2% in terms of dose and within 1 mm in terms of distance.

  8. Selection of voxel size and photon number in voxel-based Monte Carlo method: criteria and applications.

    Science.gov (United States)

    Li, Dong; Chen, Bin; Ran, Wei Yu; Wang, Guo Xiang; Wu, Wen Juan

    2015-01-01

    The voxel-based Monte Carlo method (VMC) is now a gold standard in the simulation of light propagation in turbid media. For complex tissue structures, however, the computational cost will be higher when small voxels are used to improve smoothness of tissue interface and a large number of photons are used to obtain accurate results. To reduce computational cost, criteria were proposed to determine the voxel size and photon number in 3-dimensional VMC simulations with acceptable accuracy and computation time. The selection of the voxel size can be expressed as a function of tissue geometry and optical properties. The photon number should be at least 5 times the total voxel number. These criteria are further applied in developing a photon ray splitting scheme of local grid refinement technique to reduce computational cost of a nonuniform tissue structure with significantly varying optical properties. In the proposed technique, a nonuniform refined grid system is used, where fine grids are used for the tissue with high absorption and complex geometry, and coarse grids are used for the other part. In this technique, the total photon number is selected based on the voxel size of the coarse grid. Furthermore, the photon-splitting scheme is developed to satisfy the statistical accuracy requirement for the dense grid area. Result shows that local grid refinement technique photon ray splitting scheme can accelerate the computation by 7.6 times (reduce time consumption from 17.5 to 2.3 h) in the simulation of laser light energy deposition in skin tissue that contains port wine stain lesions.

  9. Do you believe in phantoms?

    CERN Document Server

    Rosaria Marraffino

    2015-01-01

    “Phantoms” are tools that simulate a therapy’s response by mimicking the conditions of the human body. They are required in hadron therapy in order to optimise and verify the therapy before performing it on the patient. The better the phantom, the more accurate the treatment plan and the more effective the therapy. In the framework of the EU-funded project ENTERVISION*, a team of CERN researchers has designed an innovative piece of equipment able to evaluate radiobiology-related parameters in a very accurate way.   The ENTERVISION phantom being tested at HIT. A key challenge in hadron therapy – i.e. the medical use of hadrons to treat cancer – is to evaluate the biological effect of the delivered radiation. This can be achieved by using accurate dosimetry techniques to study the biological response in terms of the dose deposited and other physical parameters of the beam, such as the Linear Energy Transfer (LET). The job of the “phan...

  10. The phantom limb in dreams.

    Science.gov (United States)

    Brugger, Peter

    2008-12-01

    Mulder and colleagues [Mulder, T., Hochstenbach, J., Dijkstra, P. U., Geertzen, J. H. B. (2008). Born to adapt, but not in your dreams. Consciousness and Cognition, 17, 1266-1271.] report that a majority of amputees continue to experience a normally-limbed body during their night dreams. They interprete this observation as a failure of the body schema to adapt to the new body shape. The present note does not question this interpretation, but points to the already existing literature on the phenomenology of the phantom limb in dreams. A summary of published investigations is complemented by a note on phantom phenomena in the dreams of paraplegic patients and persons born without a limb. Integration of the available data allows the recommendation for prospective studies to consider dream content in more detail. For instance, "adaptation" to the loss of a limb can also manifest itself by seeing oneself surrounded by amputees. Such projective types of anosognosia ("transitivism") in nocturnal dreams should also be experimentally induced in normally-limbed individuals, and some relevant techniques are mentioned.

  11. Development of a HIFU Phantom

    Science.gov (United States)

    King, Randy L.; Herman, Bruce A.; Maruvada, Subha; Wear, Keith A.; Harris, Gerald R.

    2007-05-01

    The field of high intensity focused ultrasound (HIFU) is developing rapidly. For basic research, quality control, and regulatory assessment a reusable phantom that has both thermal and acoustic properties close to that of soft tissue is critical. A hydrogel-based tissue mimicking material (TMM) has been developed that shows promise for such a phantom. The acoustic attenuation, speed of sound, B/A, thermal diffusivity and conductivity, as well as the cavitation threshold, were measured and found to mimic published values for soft tissue. The attenuation of 0.53f1.04 from 1 MHz to 8 MHz, as well as the sound speed of 1565 m/s and the tissue-like image quality, indicate the usefulness of the TMM for ultrasound imaging applications. These properties along with the thermal conductivity of 0.58 W/m- °C, diffusivity of 0.15 (mm2)/s, and the ability to withstand temperatures above 95 °C make this material appropriate for HIFU applications. The TMM also allows for the embedding of thermocouples and the formation of wall-less vessels that do not deteriorate as a result of continuous flow of blood mimicking fluids through the material. Tissue characteristics are strongly dependent on the fabrication technique, and care must be taken to achieve reproducible results. Note: This research was supported by the Defense Advanced Research Projects Agency (DARPA).

  12. Analytical calculation of proton linear energy transfer in voxelized geometries including secondary protons.

    Science.gov (United States)

    Sanchez-Parcerisa, D; Cortés-Giraldo, M A; Dolney, D; Kondrla, M; Fager, M; Carabe, A

    2016-02-21

    In order to integrate radiobiological modelling with clinical treatment planning for proton radiotherapy, we extended our in-house treatment planning system FoCa with a 3D analytical algorithm to calculate linear energy transfer (LET) in voxelized patient geometries. Both active scanning and passive scattering delivery modalities are supported. The analytical calculation is much faster than the Monte-Carlo (MC) method and it can be implemented in the inverse treatment planning optimization suite, allowing us to create LET-based objectives in inverse planning. The LET was calculated by combining a 1D analytical approach including a novel correction for secondary protons with pencil-beam type LET-kernels. Then, these LET kernels were inserted into the proton-convolution-superposition algorithm in FoCa. The analytical LET distributions were benchmarked against MC simulations carried out in Geant4. A cohort of simple phantom and patient plans representing a wide variety of sites (prostate, lung, brain, head and neck) was selected. The calculation algorithm was able to reproduce the MC LET to within 6% (1 standard deviation) for low-LET areas (under 1.7 keV μm(-1)) and within 22% for the high-LET areas above that threshold. The dose and LET distributions can be further extended, using radiobiological models, to include radiobiological effectiveness (RBE) calculations in the treatment planning system. This implementation also allows for radiobiological optimization of treatments by including RBE-weighted dose constraints in the inverse treatment planning process.

  13. Phantom pain and phantom sensations in upper limb amputees : an epidemiological study

    NARCIS (Netherlands)

    Kooijman, CM; Dijkstra, PU; Geertzen, JHB; Elzinga, A; van der Schans, CP

    2000-01-01

    Phantom pain in subjects with an amputated limb is a well-known problem. However, estimates of the prevalence of phantom pain differ considerably in the literature. Various factors associated with phantom pain have been described including pain before the amputation, gender, dominance, and time elap

  14. Unifying phantom inflation with late-time acceleration: scalar phantom-non-phantom transition model and generalized holographic dark energy

    CERN Document Server

    Nojiri, S; Nojiri, Shin'ichi; Odintsov, Sergei D.

    2005-01-01

    The unifying approach to early-time and late-time universe based on phantom cosmology is proposed. We consider gravity-scalar system which contains usual potential and scalar coupling function in front of kinetic term. As a result, the possibility of phantom-non-phantom transition appears in such a way that universe could have effectively phantom equation of state at early time as well as at late time. In fact, the oscillating universe may have several phantom and non-phantom phases. As a second model we suggest generalized holographic dark energy where infrared cutoff is identified with combination of FRW parameters: Hubble constant, particle and future horizons, cosmological constant and universe life-time (if finite). Depending on the specific choice of the model the number of interesting effects occur: the possibility to solve the coincidence problem, crossing of phantom divide and unification of early-time inflationary and late-time accelerating phantom universe. The bound for holographic entropy which d...

  15. Age-dependency of analgesia elicited by intraoral sucrose in acute and persistent pain models.

    Science.gov (United States)

    Anseloni, Vanessa C Z; Weng, H-R; Terayama, R; Letizia, David; Davis, Barry J; Ren, Ke; Dubner, Ronald; Ennis, Matthew

    2002-05-01

    mechanisms and that an enhanced sucrose effect takes place in hyperalgesic, inflamed animals as compared to naive animals. Taken together, these results indicate that intraoral sucrose alleviates transient pain in response to thermal and mechanical stimuli, and also effectively reduces inflammatory hyperalgesia and allodynia. Sucrose-induced analgesia is age-dependent and limited to the pre-weaning period in rats. The age-dependency of sucrose-induced analgesia and its differential maturation for the fore- and hindpaw may be due to developmental changes in endogenous analgesic mechanisms and developmental modulation of the interaction between gustatory and pain modulatory pathways.

  16. Age-dependent decrease in the hepatic uptake and biliary excretion of ouabain in rats.

    Science.gov (United States)

    Ohta, M; Kanai, S; Sato, Y; Kitani, K

    1988-03-01

    The biliary excretion of i.v. injected ouabain was examined in male and female Wistar-derived rats in relation to age. The hepatic uptake velocity for ouabain was also determined in isolated hepatocyte preparations obtained from male rats of various ages. Biliary recovery values of ouabain (percent of the dose) were fairly comparable for young male and female rats (3-4 month old). Recovery progressively decreased with age, the first 10-min recoveries at 24 months being about one-third those of respective young values in both sexes. A significant linear relation was demonstrated between the first 10-min recovery (Y, percent of the dose) and rat age (X, month), yielding the relations of Y = 17.75-0.43X for males and Y = 18.99-0.43X for females respectively. Similarly, the initial uptake velocity (Y, nmol/mg/min) for ouabain decreased in a linear fashion with age (X, month), yielding a significant negative correlation (Y = 0.704-0.0021X, r = -0.839, P less than 0.005, N = 21) at an ouabain concentration of 8 microM. Kinetic studies using non-linear regression analysis revealed a significantly lower Vmax value (0.533 +/- 0.041 nmol/mg/min) in old (24-29 months) rats compared to the young (4-4.5 months) value (1.193 +/- 0.105 nmol per mg/min, P less than 0.05), while the affinity constant (Km, microM) did not differ significantly between young and old animals (203.12 +/- 25.42 microM in young rats vs 283.68 +/- 28.90 microM in old rats, mean +/- SE, 0.05 less than P less than 0.1). The results of the present study suggest that the age-dependent decrease in the biliary recovery of i.v. injected ouabain in rats can be largely explained by the decrease with age in the hepatic uptake of ouabain. Furthermore, the results provide further support for our previous thesis that the decrease in the lateral mobility of hepatocyte plasma membrane proteins, as revealed by the fluorescence recovery after photobleaching technique, may play a significant role in the age-dependent

  17. Age-dependent changes of monocarboxylate transporter 8 availability in the postnatal murine retina

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Henning

    2016-08-01

    Full Text Available The thyroid hormones (TH triiodothyronine (T3 and its prohormone thyroxine (T4 are crucial for retinal development and function, and increasing evidence points at TH dysregulation as a cause for retinal degenerative diseases. Thus, precise regulation of retinal TH supply is required for proper retinal function, but knowledge on these mechanisms is still fragmentary. Several transmembrane transporters have been described as key regulators of TH availability in target tissues of which the monocarboxylate transporter 8 (MCT8, a high affinity transporter for T4 and T3, plays an essential role in the central nervous system. Moreover, in the embryonic chicken retina, MCT8 is highly expressed, but the postnatal availability of MCT8 in the mammalian retina was not reported to date. In the present study, spatiotemporal retinal MCT8 availability was examined in mice of different age. For this purpose, we quantified expression levels of Mct8 via Real-Time Reverse-Transcriptase PCR in mouse eyecups (C57BL/6 of juvenile and adult age groups. Additionally, age-dependent MCT8 protein levels were quantified via Western blotting and localized via immunofluorescence confocal microscopy. While no difference in Mct8 expression levels could be detected between age groups, MCT8 protein levels in juvenile animals were about two times higher than in adult animals based on Western blot analyses. Immunohistochemical analyses showed that MCT8 immunoreactivity in the eyecup was restricted to the retina and the retinal pigment epithelium. In juvenile mice, MCT8 was broadly observed along the apical membrane of the retinal pigment epithelium, tightly surrounding photoreceptor outer segments. Distinct immunopositive staining was also detected in the inner nuclear layer and the ganglion cell layer. However, in adult specimens, immunoreactivity visibly declined in all layers, which was in line with Western blot analyses. Since MCT8 was abundantly present in juvenile and about

  18. Quality control of geological voxel models using experts' gaze

    NARCIS (Netherlands)

    Maanen, van Peter-Paul; Busschers, Freek S.; Brouwer, Anne-Marie; Meulendijk, van der Michiel J.; Erp, van Jan B.F.

    2015-01-01

    Due to an expected increase in geological voxel model data-flow and user demands, the development of improved quality control for such models is crucial. This study explores the potential of a new type of quality control that improves the detection of errors by just using gaze behavior of 12 geologi

  19. Finding significantly connected voxels based on histograms of connection strengths

    DEFF Research Database (Denmark)

    Kasenburg, Niklas; Pedersen, Morten Vester; Darkner, Sune

    2016-01-01

    -distribution and significance is determined using the false discovery rate (FDR). Segmentations are based on significantly connected voxels and their FDR. In this work we focus on the thalamus and the target regions were chosen by dividing the cortex into a prefrontal/temporal zone, motor zone, somatosensory zone and a parieto...

  20. Vessel-guided airway segmentation based on voxel classification

    DEFF Research Database (Denmark)

    Lo, Pechin Chien Pau; Sporring, Jon; Ashraf, Haseem;

    2008-01-01

    This paper presents a method for improving airway tree segmentation using vessel orientation information. We use the fact that an airway branch is always accompanied by an artery, with both structures having similar orientations. This work is based on a  voxel classification airway segmentation...

  1. Robust Segmentation of Voxel Shapes using Medial Surfaces

    NARCIS (Netherlands)

    Reniers, Dennie; Telea, Alexandru

    2008-01-01

    We present a new patch-type segmentation method for 3D voxel shapes based on the medial surface, also called surface skeleton. The boundaries of the simplified fore- and background skeletons map one-to-one to increasingly fuzzy, soft convex, respectively concave, edges of the shape. Using this prope

  2. Monte Carlo dose calculation in dental amalgam phantom.

    Science.gov (United States)

    Aziz, Mohd Zahri Abdul; Yusoff, A L; Osman, N D; Abdullah, R; Rabaie, N A; Salikin, M S

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  3. Monte carlo dose calculation in dental amalgam phantom

    Directory of Open Access Journals (Sweden)

    Mohd Zahri Abdul Aziz

    2015-01-01

    Full Text Available It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC. On the other hand, computed tomography (CT images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  4. SU-E-T-117: Dose to Organs Outside of CT Scan Range- Monte Carlo and Hybrid Phantom Approach

    Energy Technology Data Exchange (ETDEWEB)

    Pelletier, C; Jung, J [East Carolina University, Greenville, NC (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Lee, C [National Cancer Institute, Rockville, MD (United States)

    2014-06-01

    Purpose: Epidemiological study of second cancer risk for cancer survivors often requires the dose to normal tissues located outside the anatomy covered by radiological imaging, which is usually limited to tumor and organs at risk. We have investigated the feasibility of using whole body computational human phantoms for estimating out-of-field organ doses for patients treated by Intensity Modulated Radiation Therapy (IMRT). Methods: Identical 7-field IMRT prostate plans were performed using X-ray Voxel Monte Carlo (XVMC), a radiotherapy-specific Monte Carlo transport code, on the computed tomography (CT) images of the torso of an adult male patient (175 cm height, 66 kg weight) and an adult male hybrid computational phantom with the equivalent body size. Dose to the liver, right lung, and left lung were calculated and compared. Results: Considerable differences are seen between the doses calculated by XVMC for the patient CT and the hybrid phantom. One major contributing factor is the treatment method, deep inspiration breath hold (DIBH), used for this patient. This leads to significant differences in the organ position relative to the treatment isocenter. The transverse distances from the treatment isocenter to the inferior border of the liver, left lung, and right lung are 19.5cm, 29.5cm, and 30.0cm, respectively for the patient CT, compared with 24.3cm, 36.6cm, and 39.1cm, respectively, for the hybrid phantom. When corrected for the distance, the mean doses calculated using the hybrid phantom are within 28% of those calculated using the patient CT. Conclusion: This study showed that mean dose to the organs located in the missing CT coverage can be reconstructed by using whole body computational human phantoms within reasonable dosimetric uncertainty, however appropriate corrections may be necessary if the patient is treated with a technique that will significantly deform the size or location of the organs relative to the hybrid phantom.

  5. Age-Dependent Susceptibility to Enteropathogenic Escherichia coli (EPEC Infection in Mice.

    Directory of Open Access Journals (Sweden)

    Aline Dupont

    2016-05-01

    Full Text Available Enteropathogenic Escherichia coli (EPEC represents a major causative agent of infant diarrhea associated with significant morbidity and mortality in developing countries. Although studied extensively in vitro, the investigation of the host-pathogen interaction in vivo has been hampered by the lack of a suitable small animal model. Using RT-PCR and global transcriptome analysis, high throughput 16S rDNA sequencing as well as immunofluorescence and electron microscopy, we characterize the EPEC-host interaction following oral challenge of newborn mice. Spontaneous colonization of the small intestine and colon of neonate mice that lasted until weaning was observed. Intimate attachment to the epithelial plasma membrane and microcolony formation were visualized only in the presence of a functional bundle forming pili (BFP and type III secretion system (T3SS. Similarly, a T3SS-dependent EPEC-induced innate immune response, mediated via MyD88, TLR5 and TLR9 led to the induction of a distinct set of genes in infected intestinal epithelial cells. Infection-induced alterations of the microbiota composition remained restricted to the postnatal period. Although EPEC colonized the adult intestine in the absence of a competing microbiota, no microcolonies were observed at the small intestinal epithelium. Here, we introduce the first suitable mouse infection model and describe an age-dependent, virulence factor-dependent attachment of EPEC to enterocytes in vivo.

  6. Microscale Mechanism of Age Dependent Wetting Properties of Prickly Pear Cacti (Opuntia).

    Science.gov (United States)

    Rykaczewski, Konrad; Jordan, Jacob S; Linder, Rubin; Woods, Erik T; Sun, Xiaoda; Kemme, Nicholas; Manning, Kenneth C; Cherry, Brian R; Yarger, Jeffery L; Majure, Lucas C

    2016-09-13

    Cacti thrive in xeric environments through specialized water storage and collection tactics such as a shallow, widespread root system that maximizes rainwater absorption and spines adapted for fog droplet collection. However, in many cacti, the epidermis, not the spines, dominates the exterior surface area. Yet, little attention has been dedicated to studying interactions of the cactus epidermis with water drops. Surprisingly, the epidermis of plants in the genus Opuntia, also known as prickly pear cacti, has water-repelling characteristics. In this work, we report that surface properties of cladodes of 25 taxa of Opuntia grown in an arid Sonoran climate switch from water-repelling to superwetting under water impact over the span of a single season. We show that the old cladode surfaces are not superhydrophilic, but have nearly vanishing receding contact angle. We study water drop interactions with, as well as nano/microscale topology and chemistry of, the new and old cladodes of two Opuntia species and use this information to uncover the microscopic mechanism underlying this phenomenon. We demonstrate that composition of extracted wax and its contact angle do not change significantly with time. Instead, we show that the reported age dependent wetting behavior primarily stems from pinning of the receding contact line along multilayer surface microcracks in the epicuticular wax that expose the underlying highly hydrophilic layers.

  7. Age-dependent association of KIBRA gene polymorphism with Alzheimer's disease in Han Chinese.

    Science.gov (United States)

    Wang, Hui-Fu; Tan, Lan; Yu, Jin-Tai; Ma, Xiao-Ying; Liu, Qiu-Yan; Wang, Wei

    2013-12-01

    Genetic factors play an important role in the Alzheimer's disease (AD) development and memory impairment is a cardinal clinical feature of AD. Kidney and brain expressed protein (KIBRA), owing to its connection with human episodic memory, became an interesting candidate gene for AD. Recently, KIBRA (rs17070145) was reported to be associated with AD in the genetic and functional levels in Caucasian and African-American, and the association might be different across age groups. To investigate the possibility of age-dependent association of KIBRA with AD in Asian, we conducted an independent replication study in a cohort of 1,586 subjects from Han Chinese (including 790 LOAD patients and 796 healthy controls). The results revealed no significant differences in the distributions of genotype or allele between LOAD and control groups in the total sample. However, when these data were stratified by their age, we observed a significant difference in the genotypes and alleles frequencies (genotype: p = 0.004, allele: p = 0.035) in the young subgroup. Moreover, the association was further demonstrated in logistic regression analysis (rs17070145: p = 0.045, OR = 0.428). Our data suggested that KIBRA might associate with younger AD patients (≤74 years) in a Northern Han Chinese population.

  8. Age-dependent relevance of endogenous 5-lipoxygenase derivatives in anxiety-like behavior in mice.

    Science.gov (United States)

    Leo, Luciana M; Almeida-Corrêa, Suellen; Canetti, Claudio A; Amaral, Olavo B; Bozza, Fernando A; Pamplona, Fabricio A

    2014-01-01

    When 5-lipoxygenase (5-LO) is inhibited, roughly half of the CNS effect of the prototypic endocannabinoid anandamide (AEA) is lost. Therefore, we decided to investigate whether inhibiting this enzyme would influence physiological functions classically described as being under control of the endocannabinoid system. Although 5-LO inhibition by MK-886 reduced lipoxin A4 levels in the brain, no effect was found in the elevated plus maze (EPM), even at the highest possible doses, via i.p. (10 mg/kg,) or i.c.v. (500 pmol/2 µl) routes. Accordingly, no alterations in anxiety-like behavior in the EPM test were observed in 5-LO KO mice. Interestingly, aged mice, which show reduced circulating lipoxin A4 levels, were sensitive to MK-886, displaying an anxiogenic-like state in response to treatment. Moreover, exogenous lipoxin A4 induced an anxiolytic-like profile in the EPM test. Our findings are in line with other reports showing no difference between FLAP KO or 5-LO KO and their control strains in adult mice, but increased anxiety-like behavior in aged mice. We also show for the first time that lipoxin A4 affects mouse behavior. In conclusion, we propose an age-dependent relevancy of endogenous 5-LO derivatives in the modulation of anxiety-like behavior, in addition to a potential for exogenous lipoxin A4 in producing an anxiolytic-like state.

  9. Large-scale age-dependent skewed sex ratio in a sexually dimorphic avian scavenger.

    Science.gov (United States)

    Lambertucci, Sergio A; Carrete, Martina; Donázar, José Antonio; Hiraldo, Fernando

    2012-01-01

    Age-dependent skewed sex ratios have been observed in bird populations, with adult males generally outnumbering females. This trend is mainly driven by higher female mortality, sometimes associated with anthropogenic factors. Despite the large amount of work on bird sex ratios, research examining the spatial stability of adult sex ratios is extremely scarce. The Andean condor (Vultur gryphus) is the only bird of prey with strong sexual dimorphism favouring males (males are 30% heavier than females). By examining data from most of its South-American range, we show that while the juvenile sex ratio is balanced, or even female-skewed, the sex ratio becomes increasing male-skewed with age, with adult males outnumbering females by >20%, and, in some cases by four times more. This result is consistent across regions and independent of the nature of field data. Reasons for this are unknown but it can be hypothesized that the progressive disappearance of females may be associated with mortality caused by anthropogenic factors. This idea is supported by the asymmetric habitat use by the two sexes, with females scavenging in more humanized areas. Whatever the cause, male-skewed adult sex ratios imply that populations of this endangered scavenger face higher risks of extinction than previously believed.

  10. [Age-dependent changes in mRNA transport (nucleus-cytoplasm)].

    Science.gov (United States)

    Müller, W E; Agutter, P S; Prochnow, D J; Fasold, H; Sève, A P; Tsiapalis, C M; Schröder, H C

    1993-01-01

    Transport of mRNA from nucleus to cytoplasm is an ATP-dependent process which occurs strictly vectorially. Because the mRNA is structurally bound during transport, mRNA transport is a "solid-state" process consisting of i) mRNA release from the nuclear matrix, ii) mRNA translocation through the nuclear pore, and iii) cytoskeletal binding. We identified and purified the following components involved in the translocation step: i) the nuclear envelope (NE) nucleoside triphosphatase (NTPase) which is stimulated by the 3'poly(A) tail of mRNA, ii) the poly(A)-recognizing mRNA carrier, iii) the NE protein kinase, and iv) the NE phosphatase. In addition, we found that an RNA helicase activity is present in NE, which also may be involved in RNA transport. Our results show that, besides poly(A), also double-stranded RNA structures may modulate RNA export. The amount of mRNA released from nuclei markedly decreases with age. Evidence is presented that this age-dependent change is caused by an impairment of polyadenylation of mRNA, hnRNA processing, release of mRNA from nuclear matrix, and translocations of mRNA from nuclear to cytoplasmic compartment (decrease in activities of NE NTPase, protein kinase, and phosphatase; decrease in poly(A)-binding affinity of mRNA carrier).

  11. Age-dependent modulation of cortical transcriptomes in spinal cord injury and repair.

    Directory of Open Access Journals (Sweden)

    Anne Jaerve

    Full Text Available Both injury and aging of the central nervous system reportedly produce profound changes in gene expression. Therefore, aging may interfere with the success of therapeutic interventions which were tailored for young patients. Using genome-scale transcriptional profiling, we identified distinct age-dependent expression profiles in rat sensorimotor cortex during acute, subacute and chronic phases of spinal cord injury (SCI. Aging affects the cortical transcriptomes triggered by transection of the corticospinal tract as there was only a small overlap between the significantly lesion-regulated genes in both age groups. Over-representation analysis of the lesion-regulated genes revealed that, in addition to biological processes in common, such as lipid metabolism, others, such as activation of complement cascade, were specific for aged animals. When a recently developed treatment to suppress fibrotic scarring (anti-scarring treatment AST was applied to the injured spinal cord of aged (22 months and young (2 months rats, we found that the cortical gene expression in old rats was modulated to resemble regeneration-associated profiles of young animals including the up-regulation of known repair promoting growth and transcription factors at 35 dpo. In combination with recent immunohistochemical findings demonstrating regenerative axon growth upon AST in aged animals, the present investigation on the level of gene expression strongly supports the feasibility of a successful AST therapy in elderly patients.

  12. Collagene order of articular cartilage by clinical magnetic resonance images and its age dependency

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, P.; Gruender, W. [Inst. of Medical Physics and Biophysics, Univ. of Leipzig (Germany)

    2005-07-01

    The present papers describes a novel method to obtain information on the degree of order of the collagen network of the knee meniscal cartilage by means of a single clinical MRI. Images were obtained from 34 healthy volunteers aged between 6 and 76 years as well as from one patient with clinically-diagnosed arthrosis at the age of 32 and 37 years. A siemens vision (1.5 T) MRT with TR = 750 ms, TE = 50 ms, FoV = 160 mm, and Matrix 512 x 512 was used for this purpose. The MR signal intensities of the cartilage were read out along slices with constant height above the subchondral bone and plotted versus the actual angle to the external magnetic field. The obtained intensity curves were fitted by a model distribution, and the degree of order of the collagen fibers was calculated. For the knee meniscal cartilage, there was an age-dependency of the degree of order and a significant deviation of the volunteer with arthrosis from the normal curve. The results are discussed in view of the arcade model and of a possible use of non-invasive clinical MRT for the detection of early arthrotic changes of cartilage. (orig.)

  13. Large-scale age-dependent skewed sex ratio in a sexually dimorphic avian scavenger.

    Directory of Open Access Journals (Sweden)

    Sergio A Lambertucci

    Full Text Available Age-dependent skewed sex ratios have been observed in bird populations, with adult males generally outnumbering females. This trend is mainly driven by higher female mortality, sometimes associated with anthropogenic factors. Despite the large amount of work on bird sex ratios, research examining the spatial stability of adult sex ratios is extremely scarce. The Andean condor (Vultur gryphus is the only bird of prey with strong sexual dimorphism favouring males (males are 30% heavier than females. By examining data from most of its South-American range, we show that while the juvenile sex ratio is balanced, or even female-skewed, the sex ratio becomes increasing male-skewed with age, with adult males outnumbering females by >20%, and, in some cases by four times more. This result is consistent across regions and independent of the nature of field data. Reasons for this are unknown but it can be hypothesized that the progressive disappearance of females may be associated with mortality caused by anthropogenic factors. This idea is supported by the asymmetric habitat use by the two sexes, with females scavenging in more humanized areas. Whatever the cause, male-skewed adult sex ratios imply that populations of this endangered scavenger face higher risks of extinction than previously believed.

  14. Age-dependent trajectories differ between within-pair and extra-pair paternity success.

    Science.gov (United States)

    Hsu, Y-H; Simons, M J P; Schroeder, J; Girndt, A; Winney, I S; Burke, T; Nakagawa, S

    2017-02-24

    Reproductive success is associated with age in many taxa, increasing in early life followed by reproductive senescence. In socially monogamous but genetically polygamous species, this generates the interesting possibility of differential trajectories of within-pair and extra-pair siring success with age in males. We investigate these relationships simultaneously using within-individual analyses with 13 years of data from an insular house sparrow (Passer domesticus) population. As expected, we found that both within- and extra-pair paternity success increased with age, followed by a senescence-like decline. However, the age trajectories of within- and extra-pair paternity successes differed significantly, with the extra-pair paternity success increasing faster, although not significantly, in early life, and showing a delayed decline by 1.5 years on average later in life compared to within-pair paternity success. These different trajectories indicate that the two alternative mating tactics should have age-dependent pay-offs. Males may partition their reproductive effort between within- and extra-pair matings depending on their current age to reap the maximal combined benefit from both strategies. The interplay between these mating strategies and age-specific mortality may explain the variation in rates of extra-pair paternity observed within and between species.

  15. Chronic BDNF deficiency leads to an age-dependent impairment in spatial learning.

    Science.gov (United States)

    Petzold, Anne; Psotta, Laura; Brigadski, Tanja; Endres, Thomas; Lessmann, Volkmar

    2015-04-01

    Brain-derived neurotrophic factor (BDNF) is a crucial mediator of neural plasticity and, consequently, of memory formation. In hippocampus-dependent learning tasks BDNF also seems to play an essential role. However, there are conflicting results concerning the spatial learning ability of aging BDNF(+/-) mice in the Morris water maze paradigm. To evaluate the effect of chronic BDNF deficiency in the hippocampus on spatial learning throughout life, we conducted a comprehensive study to test differently aged BDNF(+/-) mice and their wild type littermates in the Morris water maze and to subsequently quantify their hippocampal BDNF protein levels as well as expression levels of TrkB receptors. We observed an age-dependent learning deficit in BDNF(+/-) animals, starting at seven months of age, despite stable hippocampal BDNF protein expression and continual decline of TrkB receptor expression throughout aging. Furthermore, we detected a positive correlation between hippocampal BDNF protein levels and learning performance during the probe trial in animals that showed a good learning performance during the long-term memory test.

  16. Assessment of {sup 226}Ra age-dependent dose from water intake

    Energy Technology Data Exchange (ETDEWEB)

    Porntepkasemsan, Boonsom [Research and Development Group, Thailand Institute of Nuclear Technology, Vibhavadi Rangsit Road, Bangkok 10900 (Thailand)], E-mail: boonsom@oaep.go.th; Srisuksawad, Kanitha [Research and Development Group, Thailand Institute of Nuclear Technology, Vibhavadi Rangsit Road, Bangkok 10900 (Thailand)

    2008-11-15

    The radioactivity in canal and ground waters collected in a 2-year long observation from the vicinity of the Rare Earth Research and Development Center (RRDC), Phathumthani Province, Thailand, was measured in order to determine the concentration of {sup 226}Ra and to estimate the age-dependent effective dose to humans due to consumption. {sup 226}Ra activities in both canal and ground waters were well below the WHO guidance level for drinking water quality of 1 Bq L{sup -1}. The highest {sup 226}Ra effective doses per year were found for infants and teens. However, the observed levels of calculated {sup 226}Ra effective doses for all age groups in both canal and ground waters show satisfactory low values (less than 15 {mu}Sv yr{sup -1}). These values are acceptable in accordance with the WHO recommended reference dose level of 100 {mu}Sv yr{sup -1} from water intake of 2 L day{sup -1}.

  17. Steroidogenic Factor 1 in the Ventromedial Nucleus of the Hypothalamus Regulates Age-Dependent Obesity

    Science.gov (United States)

    Kinyua, Ann W.; Yang, Dong Joo; Chang, Inik; Kim, Ki Woo

    2016-01-01

    The ventromedial nucleus of the hypothalamus (VMH) is important for the regulation of whole body energy homeostasis and lesions in the VMH are reported to result in massive weight gain. The nuclear receptor steroidogenic factor 1 (SF-1) is a known VMH marker as it is exclusively expressed in the VMH region of the brain. SF-1 plays a critical role not only in the development of VMH but also in its physiological functions. In this study, we generated prenatal VMH-specific SF-1 KO mice and investigated age-dependent energy homeostasis regulation by SF-1. Deletion of SF-1 in the VMH resulted in dysregulated insulin and leptin homeostasis and late onset obesity due to increased food intake under normal chow and high fat diet conditions. In addition, SF-1 ablation was accompanied by a marked reduction in energy expenditure and physical activity and this effect was significantly pronounced in the aged mice. Taken together, our data indicates that SF-1 is a key component in the VMH-mediated regulation of energy homeostasis and implies that SF-1 plays a protective role against metabolic stressors including aging and high fat diet. PMID:27598259

  18. Age-Dependent Defects of Regulatory B Cells in Wiskott-Aldrich Syndrome Gene Knockout Mice.

    Directory of Open Access Journals (Sweden)

    Tadafumi Yokoyama

    Full Text Available The Wiskott-Aldrich syndrome (WAS is a rare X-linked primary immunodeficiency characterized by recurrent infections, thrombocytopenia, eczema, and high incidence of malignancy and autoimmunity. The cellular mechanisms underlying autoimmune complications in WAS have been extensively studied; however, they remain incompletely defined. We investigated the characteristics of IL-10-producing CD19+CD1dhighCD5+ B cells (CD1dhighCD5+ Breg obtained from Was gene knockout (WKO mice and found that their numbers were significantly lower in these mice compared to wild type (WT controls. Moreover, we found a significant age-dependent reduction of the percentage of IL-10-expressing cells in WKO CD1dhighCD5+ Breg cells as compared to age-matched WT control mice. CD1dhighCD5+ Breg cells from older WKO mice did not suppress the in vitro production of inflammatory cytokines from activated CD4+ T cells. Interestingly, CD1dhighCD5+ Breg cells from older WKO mice displayed a basal activated phenotype which may prevent normal cellular responses, among which is the expression of IL-10. These defects may contribute to the susceptibility to autoimmunity with age in patients with WAS.

  19. Age dependence of spleen- and muscle-corrected hepatic signal enhancement on hepatobiliary phase gadoxetate MRI

    Energy Technology Data Exchange (ETDEWEB)

    Matoori, Simon [Paracelsus Medical University Salzburg, Department of Radiology, Salzburg (Austria); Hirslanden Clinic St. Anna, Clinical Research Group, Lucerne (Switzerland); Froehlich, Johannes M. [Hirslanden Clinic St. Anna, Clinical Research Group, Lucerne (Switzerland); ETH Zurich, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Zurich (Switzerland); Cantonal Hospital Winterthur, Department of Radiology, Winterthur (Switzerland); Breitenstein, Stefan [Cantonal Hospital Winterthur, Department of Surgery, Clinic for Visceral and Thoracic Surgery, Winterthur (Switzerland); Doert, Aleksis [Cantonal Hospital Winterthur, Department of Radiology, Winterthur (Switzerland); Pozdniakova, Viktoria [Stavanger University Hospital, Department of Radiology, Stavanger (Norway); Koh, Dow-Mu [Royal Marsden Hospital, Department of Radiology, Surrey, England (United Kingdom); Gutzeit, Andreas [Paracelsus Medical University Salzburg, Department of Radiology, Salzburg (Austria); Hirslanden Clinic St. Anna, Clinical Research Group, Lucerne (Switzerland); Cantonal Hospital Winterthur, Department of Radiology, Winterthur (Switzerland)

    2016-06-15

    To identify correlations of signal enhancements (SE) and SE normalized to reference tissues of the spleen, kidney, liver, musculus erector spinae (MES) and ductus hepatocholedochus (DHC) on hepatobiliary phase gadoxetate-enhanced MRI with patient age in non-cirrhotic patients. A heterogeneous cohort of 131 patients with different clinical backgrounds underwent a standardized 3.0-T gadoxetate-enhanced liver MRI between November 2008 and June 2013. After exclusion of cirrhotic patients, a cohort of 75 patients with no diagnosed diffuse liver disease was selected. The ratio of signal intensity 20 min post- to pre-contrast administration (SE) in the spleen, kidney, liver, MES and DHC, and the SE of the kidney, liver and DHC normalized to the reference tissues spleen or MES were compared to patient age. Patient age was inversely correlated with the liver SE normalized to the spleen and MES SE (both p < 0.001) and proportionally with the SE of the spleen (p = 0.043), the MES (p = 0.030) and the kidney (p = 0.022). No significant correlations were observed for the DHC (p = 0.347) and liver SE (p = 0.606). The age dependence of hepatic SE normalized to the enhancement in the spleen and MES calls for a cautious interpretation of these quantification methods. (orig.)

  20. Age-dependent effects of carotid endarterectomy or stenting on cognitive performance.

    Science.gov (United States)

    Wasser, Katrin; Hildebrandt, Helmut; Gröschel, Sonja; Stojanovic, Tomislav; Schmidt, Holger; Gröschel, Klaus; Pilgram-Pastor, Sara M; Knauth, Michael; Kastrup, Andreas

    2012-11-01

    Although evidence is accumulating that age modifies the risk of carotid angioplasty and stenting (CAS) versus endarterectomy (CEA) for patients with significant carotid stenosis, the impact of age on cognition after either CEA or CAS remains unclear. In this study, we analyzed the effects of age on cognitive performance after either CEA or CAS using a comprehensive neuropsychological test battery with parallel test forms and a control group to exclude a learning effect. The neuropsychological outcomes after revascularization were determined in 19 CAS and 27 CEA patients with severe carotid stenosis. The patients were subdivided according to their median age (battery that assessed four major cognitive domains were performed immediately before, within 72 h, and 3 months after CEA or CAS. While patients transient in patients treated with CAS. These results demonstrate an age-dependent effect of CEA and CAS on cognitive functions. In contrast to the recently observed increased clinical complication rates in older subjects after CAS compared with CEA, CEA appears to be associated with a greater, persistent decline in cognitive performance than CAS in this subgroup of patients.

  1. Proteomic identification of age-dependent protein nitration in rat skeletal muscle.

    Science.gov (United States)

    Kanski, Jaroslaw; Alterman, Michail A; Schöneich, Christian

    2003-11-15

    Age-related protein nitration was studied in skeletal muscle of Fisher 344 and Fisher 344/Brown Norway (BN) F1 rats by a proteomic approach. Proteins from young (4 months) and old (24 months) Fisher 344 rats and young (6 months) and old (34 months) Fisher 344/BN F1 animals were separated by 2-D gel electrophoresis. Western blot showed an age-related increase in the nitration of a few specific proteins, which were identified by MALDI-TOF MS and ESI-MS/MS. We identified age-dependent apparent nitration of beta-enolase, alpha-fructose aldolase, and creatine kinase, which perform important functions in muscle energy metabolism, suggesting that the nitration of such key proteins can be, in part, responsible for the decline of muscle motor function of the muscle. Furthermore, we have identified the apparent nitration of succinate dehydrogenase, rab GDP dissociation inhibitor beta (GdI-2), triosephosphate isomerase, troponin I, alpha-crystallin, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

  2. Practical applications of age-dependent reliability models and analysis of operational data

    Energy Technology Data Exchange (ETDEWEB)

    Lannoy, A.; Nitoi, M.; Backstrom, O.; Burgazzi, L.; Couallier, V.; Nikulin, M.; Derode, A.; Rodionov, A.; Atwood, C.; Fradet, F.; Antonov, A.; Berezhnoy, A.; Choi, S.Y.; Starr, F.; Dawson, J.; Palmen, H.; Clerjaud, L

    2005-07-01

    The purpose of the workshop was to present the experience of practical application of time-dependent reliability models. The program of the workshop comprises the following sessions: -) aging management and aging PSA (Probabilistic Safety Assessment), -) modeling, -) operation experience, and -) accelerating aging tests. In order to introduce time aging effect of particular component to the PSA model, it has been proposed to use the constant unavailability values on the short period of time (one year for example) calculated on the basis of age-dependent reliability models. As for modeling, it appears that the problem of too detailed statistical models for application is the lack of data for required parameters. As for operating experience, several methods of operating experience analysis have been presented (algorithms for reliability data elaboration and statistical identification of aging trend). As for accelerated aging tests, it is demonstrated that a combination of operating experience analysis with the results of accelerated aging tests of naturally aged equipment could provide a good basis for continuous operation of instrumentation and control systems.

  3. Age-dependent Characteristics in Women with Breast Cancer: Mastectomy and Reconstructive Trends at an Urban Academic Institution.

    Science.gov (United States)

    Rodby, Katherine A; Robinson, Emilie; Danielson, Kirstie K; Quinn, Karina P; Antony, Anuja K

    2016-03-01

    Breast reconstruction is an important aspect of treatment after breast cancer. Postmastectomy reconstruction bears a significant impact on a woman's postsurgical confidence, sexuality, and overall well-being. Previous studies have inferred that women under age 40 years have unique characteristics that distinguish them from an older cohort. Identifying age-dependent trends will assist with counseling women on mastectomy and reconstruction. To identify age-dependent trends, 100 consecutive women were sampled from a prospectively maintained breast reconstruction database at an urban academic institution from June 2010 through June 2013. Women were placed into two cohorts breast cancer. Younger women typically present with more aggressive features requiring oncologic treatment including chemotherapy and radiation. Mastectomy and reconstructive choices also demonstrate age-dependent characteristics. Women in younger age groups are more likely to pursue risk-reduction procedures and implant-based strategies, whereas older women had a higher propensity for abdominal-based autologous reconstruction. In addition, preferential reconstructive strategies correlate with age-dependent archetypical features of the breast (higher profile implants in younger patients; autologous reconstruction on affected side mimicking natural ptosis, and contralateral mastopexy in older patients). These trends seem to be consistent with each increasing year of age. Age-related preferences and expectations, age-dependent body habitus and breast shape, and lifetime risk play a role in the choices pursued for mastectomy and reconstruction.

  4. Oscillating phantom in $F(R)$ gravity

    CERN Document Server

    Bamba, Kazuharu

    2009-01-01

    We investigate the oscillating effective equation of state (EoS) of the universe around the phantom divide in the framework of $F(R)$ gravity. We illustrate the behavior of $F(R)$ with realizing multiple crossings of the phantom divide.

  5. Voxel-based model construction from colored tomographic images; Construcao de simuladores baseados em elementos de volume a partir de imagens tomograficas coloridas

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, Eduardo Cesar de Miranda

    2002-07-01

    This work presents a new approach in the construction of voxel-based phantoms that was implemented to simplify the segmentation process of organs and tissues reducing the time used in this procedure. The segmentation process is performed by painting tomographic images and attributing a different color for each organ or tissue. A voxel-based head and neck phantom was built using this new approach. The way as the data are stored allows an increasing in the performance of the radiation transport code. The program that calculates the radiation transport also works with image files. This capability allows image reconstruction showing isodose areas, under several points of view, increasing the information to the user. Virtual X-ray photographs can also be obtained allowing that studies could be accomplished looking for the radiographic techniques optimization assessing, at the same time, the doses in organs and tissues. The accuracy of the program here presented, called MCvoxEL, that implements this new approach, was tested by comparison to results from two modern and well-supported Monte Carlo codes. Dose conversion factors for parallel X-ray exposure were also calculated. (author)

  6. Galactosemia and phantom absence seizures

    Directory of Open Access Journals (Sweden)

    Zeynep Aydin-Özemir

    2014-01-01

    Full Text Available Generalized and focal seizures can rarely be seen in galactosemia patients, but absence seizures were not reported previously. An 18-year-old male was diagnosed as galactosemia at the age of 8 months. No family history of epilepsy was present. His absence seizures realized at the age of 9 years. Generalized 3-4 Hz spike-wave discharges were identified in his electroencephalography. Homozygous mutation at exon 6 c. 563A > G was identified. The electroencephalogram of his sibling was unremarkable. Our aim was to present the long-term follow-up of a patient diagnosed with galactosemia, who had phantom absence seizures and typical 3-4 Hz spike-wave discharges in his electroencephalogram to draw attention to this rare association.

  7. Comparison of measured and Monte Carlo calculated dose distributions in inhomogeneous phantoms in clinical electron beams

    Science.gov (United States)

    Doucet, R.; Olivares, M.; DeBlois, F.; Podgorsak, E. B.; Kawrakow, I.; Seuntjens, J.

    2003-08-01

    Calculations of dose distributions in heterogeneous phantoms in clinical electron beams, carried out using the fast voxel Monte Carlo (MC) system XVMC and the conventional MC code EGSnrc, were compared with measurements. Irradiations were performed using the 9 MeV and 15 MeV beams from a Varian Clinac-18 accelerator with a 10 × 10 cm2 applicator and an SSD of 100 cm. Depth doses were measured with thermoluminescent dosimetry techniques (TLD 700) in phantoms consisting of slabs of Solid WaterTM (SW) and bone and slabs of SW and lung tissue-equivalent materials. Lateral profiles in water were measured using an electron diode at different depths behind one and two immersed aluminium rods. The accelerator was modelled using the EGS4/BEAM system and optimized phase-space files were used as input to the EGSnrc and the XVMC calculations. Also, for the XVMC, an experiment-based beam model was used. All measurements were corrected by the EGSnrc-calculated stopping power ratios. Overall, there is excellent agreement between the corrected experimental and the two MC dose distributions. Small remaining discrepancies may be due to the non-equivalence between physical and simulated tissue-equivalent materials and to detector fluence perturbation effect correction factors that were calculated for the 9 MeV beam at selected depths in the heterogeneous phantoms.

  8. Comparison of measured and Monte Carlo calculated dose distributions in inhomogeneous phantoms in clinical electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Doucet, R [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); Olivares, M [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); DeBlois, F [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); Podgorsak, E B [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); Kawrakow, I [National Research Council Canada, Ionizing Radiation Standards Group, Ottawa K1A 0R6, Canada (Canada); Seuntjens, J [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada)

    2003-08-07

    Calculations of dose distributions in heterogeneous phantoms in clinical electron beams, carried out using the fast voxel Monte Carlo (MC) system XVMC and the conventional MC code EGSnrc, were compared with measurements. Irradiations were performed using the 9 MeV and 15 MeV beams from a Varian Clinac-18 accelerator with a 10 x 10 cm{sup 2} applicator and an SSD of 100 cm. Depth doses were measured with thermoluminescent dosimetry techniques (TLD 700) in phantoms consisting of slabs of Solid Water{sup TM} (SW) and bone and slabs of SW and lung tissue-equivalent materials. Lateral profiles in water were measured using an electron diode at different depths behind one and two immersed aluminium rods. The accelerator was modelled using the EGS4/BEAM system and optimized phase-space files were used as input to the EGSnrc and the XVMC calculations. Also, for the XVMC, an experiment-based beam model was used. All measurements were corrected by the EGSnrc-calculated stopping power ratios. Overall, there is excellent agreement between the corrected experimental and the two MC dose distributions. Small remaining discrepancies may be due to the non-equivalence between physical and simulated tissue-equivalent materials and to detector fluence perturbation effect correction factors that were calculated for the 9 MeV beam at selected depths in the heterogeneous phantoms.

  9. Specific Absorbed Fractions of Electrons and Photons for Rad-HUMAN Phantom Using Monte Carlo Method

    CERN Document Server

    Wang, Wen; Long, Peng-cheng; Hu, Li-qin

    2014-01-01

    The specific absorbed fractions (SAF) for self- and cross-irradiation are effective tools for the internal dose estimation of inhalation and ingestion intakes of radionuclides. A set of SAFs of photon and electron were calculated using the Rad-HUMAN phantom, a computational voxel phantom of Chinese adult female and created using the color photographic image of the Chinese Visible Human (CVH) data set. The model can represent most of Chinese adult female anatomical characteristics and can be taken as an individual phantom to investigate the difference of internal dose with Caucasians. In this study, the emission of mono-energetic photons and electrons of 10keV to 4MeV energy were calculated using the Monte Carlo particle transport calculation code MCNP. Results were compared with the values from ICRP reference and ORNL models. The results showed that SAF from Rad-HUMAN have the similar trends but larger than those from the other two models. The differences were due to the racial and anatomical differences in o...

  10. The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Maynard, Matthew R; Geyer, John W; Bolch, Wesley [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Aris, John P [Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL (United States); Shifrin, Roger Y, E-mail: wbolch@ufl.edu [Department of Radiology, University of Florida, Gainesville, FL (United States)

    2011-08-07

    Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR(TM) and then imported to the 3D modeling software package Rhinoceros(TM) for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations

  11. The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

    Science.gov (United States)

    Maynard, Matthew R.; Geyer, John W.; Aris, John P.; Shifrin, Roger Y.; Bolch, Wesley

    2011-08-01

    Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR™ and then imported to the 3D modeling software package Rhinoceros™ for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations in

  12. Age-dependent changes in intrinsic neuronal excitability in subiculum after status epilepticus.

    Directory of Open Access Journals (Sweden)

    Sungkwon Chung

    Full Text Available Kainic acid-induced status epilepticus (KA-SE in mature rats results in the development of spontaneous recurrent seizures and a pattern of cell death resembling hippocampal sclerosis in patients with temporal lobe epilepsy. In contrast, KA-SE in young animals before postnatal day (P 18 is less likely to cause cell death or epilepsy. To investigate whether changes in neuronal excitability occur in the subiculum after KA-SE, we examined the age-dependent effects of SE on the bursting neurons of subiculum, the major output region of the hippocampus. Patch-clamp recordings were used to monitor bursting in pyramidal neurons in the subiculum of rat hippocampal slices. Neurons were studied either one or 2-3 weeks following injection of KA or saline (control in immature (P15 or more mature (P30 rats, which differ in their sensitivity to KA as well as the long-term sequelae of the KA-SE. A significantly greater proportion of subicular pyramidal neurons from P15 rats were strong-bursting neurons and showed increased frequency-dependent bursting compared to P30 animals. Frequency-dependent burst firing was enhanced in P30, but not in P15 rats following KA-SE. The enhancement of bursting induced by KA-SE in more mature rats suggests that the frequency-dependent limitation of repetitive burst firing, which normally occurs in the subiculum, is compromised following SE. These changes could facilitate the initiation of spontaneous recurrent seizures or their spread from the hippocampus to other parts of the brain.

  13. Age-dependent effect of ozone on pulmonary eicosanoid metabolism in rabbits and rats

    Energy Technology Data Exchange (ETDEWEB)

    Gunnison, A.F.; Finkelstein, I.; Weideman, P.; Su, W.Y.; Sobo, M.; Schlesinger, R.B. (New York Univ. Medical Center, New York (USA))

    1990-11-01

    Acute exposures to ozone have previously been shown to cause quantitative changes in the spectrum of arachidonic acid (AA) metabolites in lung lavage fluid. Since age appears to be an important variable in the toxicity of inhaled ozone, we investigated its effect on ozone-induced changes in pulmonary eicosanoid metabolism. Rats and rabbits ranging in age from neonates to young adults were exposed either to air or to 1 ppm ozone for 2 hr. Lung lavage fluid was collected within 1 hr following exposure and analyzed for its content of selected eicosanoids. In both species, there was a pronounced effect of age on ozone-induced pulmonary eicosanoid metabolism. Ozone-exposed animals at the youngest ages examined had severalfold greater amounts of two products of the cyclooxygenase pathway, prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha), than did age-matched controls. This effect lessened and eventually disappeared as the animals grew toward adulthood. In rabbits, ozone also induced increases in 6-keto-prostaglandin F1 alpha and thromboxane B2, but these changes were of lesser magnitude and evident only in the youngest rabbits exposed. There was no observed effect of ozone on lung lavage content of leukothriene B4. Indices of nonspecific pulmonary damage, i.e., protein concentration in lung lavage fluid and total number and viability of lavaged lung cells, were affected by ozone exposure, but not in an age-dependent manner that correlated with changes in pulmonary eicosanoid metabolism. In vitro ozone exposure of lung macrophages from naive rabbits of the same age range as those exposed in vivo demonstrated that ozone is capable of stimulating the elaboration of PGF2 alpha and especially PGE2. However, the increase in lavage fluid PGE2 and PGF2 alpha caused by ozone inhalation could not be attributed to macrophage metabolism conclusively.

  14. [Investigation of the age-dependent development of brachygnathia inferior in the East Friesian milk sheep].

    Science.gov (United States)

    Pielmeier, Ricarda; Kerkmann, Andrea; Distl, Ottmar

    2012-01-01

    Shortness of the lower jaw (brachygnathia inferior, underbite) is a common anomaly in sheep. In order to study the age-dependent development of brachygnathia inferior, data of 73 East Friesian milk sheep from a breeding experiment over six generations were analysed. Data were recorded in regular intervals of four weeks from birth up to an age of at least 25 weeks. Brachygnathia inferior was determined by the distance between the edge of the central incisor of the lower jaw and the anterior surrounding of the upper jaw (DIFF-UK) using a measuring tape. Four main types of brachygnathia inferior were distinguished using means, standard deviations and maximum values of the individual animals.The thresholds were a maximum and mean DIFF-UK of 0.5 cm and a standard deviation of 0.266 cm. A total of 14 sheep (main types 3 and 4) showed an obvious brachygnathia inferior with mean DIFF-UK larger than 0.5 cm whereof ten animals showed a large variation of DIFF-UK values (standard deviation > 0.226 cm). Mean DIFF-UK values of 59 sheep were smaller than 0.5 cm (main types 1 and 2). One of these 59 animals had during the first four weeks of life DIFF-UK values of 1 cm and than decreasing values reaching zero within the next nine months (main type 2). Five of the 58 animals with main type 1 had a perfect occlusion of jaws, all with DIFF-UK values at zero during the whole recording period. Parents with severe or mild brachygnathia inferior had severely affected progeny. Selection of sheep for breeding with a perfect occlusion of jaws decreases the risk to pass on the hereditary disposition for brachygnathia inferior. An early inspection of potential breeding animals is advisable to detect all cases of brachygnathia inferior even if the underbite decreases in the first year of life.

  15. Suppressing an anti-inflammatory cytokine reveals a strong age-dependent survival cost in mice.

    Directory of Open Access Journals (Sweden)

    Virginia Belloni

    Full Text Available BACKGROUND: The central paradigm of ecological immunology postulates that selection acts on immunity as to minimize its cost/benefit ratio. Costs of immunity may arise because the energetic requirements of the immune response divert resources that are no longer available for other vital functions. In addition to these resource-based costs, mis-directed or over-reacting immune responses can be particularly harmful for the host. In spite of the potential importance of immunopathology, most studies dealing with the evolution of the immune response have neglected such non resource-based costs. To keep the immune response under control, hosts have evolved regulatory pathways that should be considered when studying the target of the selection pressures acting on immunity. Indeed, variation in regulation may strongly modulate the negative outcome of immune activation, with potentially important fitness consequences. METHODOLOGY/PRINCIPAL FINDINGS: Here, we experimentally assessed the survival costs of reduced immune regulation by inhibiting an anti-inflammatory cytokine (IL-10 with anti-IL-10 receptor antibodies (anti-IL-10R in mice that were either exposed to a mild inflammation or kept as control. The experiment was performed on young (3 months and old (15 months individuals, as to further assess the age-dependent cost of suppressing immune regulation. IL-10 inhibition induced high mortality in old mice exposed to the mild inflammatory insult, whereas no mortality was observed in young mice. However, young mice experienced a transitory lost in body mass when injected with the anti-IL-10R antibodies, showing that the treatment was to a lesser extent also costly for young individuals. CONCLUSIONS: These results suggest a major role of immune regulation that deserves attention when investigating the evolution of immunity, and indicate that the capacity to down-regulate the inflammatory response is crucial for late survival and longevity.

  16. Aging-dependent changes in rat heart mitochondrial glutaredoxins—Implications for redox regulation

    Directory of Open Access Journals (Sweden)

    Xing-Huang Gao

    2013-01-01

    Full Text Available Clinical and animal studies have documented that hearts of the elderly are more susceptible to ischemia/reperfusion damage compared to young adults. Recently we found that aging-dependent increase in susceptibility of cardiomyocytes to apoptosis was attributable to decrease in cytosolic glutaredoxin 1 (Grx1 and concomitant decrease in NF-κB-mediated expression of anti-apoptotic proteins. Besides primary localization in the cytosol, Grx1 also exists in the mitochondrial intermembrane space (IMS. In contrast, Grx2 is confined to the mitochondrial matrix. Here we report that Grx1 is decreased by 50–60% in the IMS, but Grx2 is increased by 1.4–2.6 fold in the matrix of heart mitochondria from elderly rats. Determination of in situ activities of the Grx isozymes from both subsarcolemmal (SSM and interfibrillar (IFM mitochondria revealed that Grx1 was fully active in the IMS. However, Grx2 was mostly in an inactive form in the matrix, consistent with reversible sequestration of the active-site cysteines of two Grx2 molecules in complex with an iron–sulfur cluster. Our quantitative evaluations of the active/inactive ratio for Grx2 suggest that levels of dimeric Grx2 complex with iron–sulfur clusters are increased in SSM and IFM in the hearts of elderly rats. We found that the inactive Grx2 can be fully reactivated by sodium dithionite or exogenous superoxide production mediated by xanthine oxidase. However, treatment with rotenone, which generates intramitochondrial superoxide through inhibition of mitochondrial respiratory chain Complex I, did not lead to Grx2 activation. These findings suggest that insufficient ROS accumulates in the vicinity of dimeric Grx2 to activate it in situ.

  17. An exact general remeshing scheme applied to conservative voxelization

    CERN Document Server

    Powell, Devon

    2014-01-01

    We derive new formulae to calculate volumes, moments, and polynomial integrals up to quadratic order over polytopes in two and three dimensions. In principle, our method can be used to derive analogous formulae for polynomials of any order in any dimensionality. By successively applying the divergence theorem, we reduce the dimensionality of the integrals from volumes to areas to lines to points. We arrive at closed-form expressions involving data local to the vertices that define the polytope, with no need for the entire polytope to be explicitly represented all at once. In addition, there are no latent assumptions regarding the convexity or connectedness of the domain. The form of these expressions is particularly well-suited to software implementations. We apply these formulae to the case of voxelizing polytopes using an exact volume-sampling approach, including the voxelization of polytopes with linearly and quadratically varying densities. We take particular care to avoid loss of numerical precision, ach...

  18. Connecting horizon pixels and interior voxels of a black hole

    CERN Document Server

    Nicolini, Piero

    2014-01-01

    In this paper we discuss to what extent one can infer details of the interior structure of a black hole based on its horizon. Recalling that black hole thermal properties are connected to the non-classical nature of gravity, we circumvent the restrictions of the no hair theorem by postulating that the black hole interior is singularity free due to violations of the usual energy conditions. Further these conditions allow one to establish a one-to-one, holographic projection between Planckian areal "bits" on the horizon and "voxels", representing the gravitational degrees of freedom in the black hole interior. We illustrate the repercussions of this idea by discussing an example of the black hole interior consisting of a de Sitter core postulated to arise from the local graviton quantum vacuum energy. It is shown that the black hole entropy can emerge as the statistical entropy of a gas of voxels.

  19. Charged black holes in phantom cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, Mubasher; Qadir, Asghar; Rashid, Muneer Ahmad [National University of Sciences and Technology, Center for Advanced Mathematics and Physics, Rawalpindi (Pakistan)

    2008-11-15

    In the classical relativistic regime, the accretion of phantom-like dark energy onto a stationary black hole reduces the mass of the black hole. We have investigated the accretion of phantom energy onto a stationary charged black hole and have determined the condition under which this accretion is possible. This condition restricts the mass-to-charge ratio in a narrow range. This condition also challenges the validity of the cosmic-censorship conjecture since a naked singularity is eventually produced due to accretion of phantom energy onto black hole. (orig.)

  20. Efficient graphics processing unit-based voxel carving for surveillance

    Science.gov (United States)

    Ober-Gecks, Antje; Zwicker, Marius; Henrich, Dominik

    2016-07-01

    A graphics processing unit (GPU)-based implementation of a space carving method for the reconstruction of the photo hull is presented. In particular, the generalized voxel coloring with item buffer approach is transferred to the GPU. The fast computation on the GPU is realized by an incrementally calculated standard deviation within the likelihood ratio test, which is applied as color consistency criterion. A fast and efficient computation of complete voxel-pixel projections is provided using volume rendering methods. This generates a speedup of the iterative carving procedure while considering all given pixel color information. Different volume rendering methods, such as texture mapping and raycasting, are examined. The termination of the voxel carving procedure is controlled through an anytime concept. The photo hull algorithm is examined for its applicability to real-world surveillance scenarios as an online reconstruction method. For this reason, a GPU-based redesign of a visual hull algorithm is provided that utilizes geometric knowledge about known static occluders of the scene in order to create a conservative and complete visual hull that includes all given objects. This visual hull approximation serves as input for the photo hull algorithm.

  1. Voxel significance mapping in epilepsy studies using subtraction ictal SPECT

    Science.gov (United States)

    Brinkmann, Benjamin H.; O'Brien, Terence J.; Webster, Desmond B.; Robins, Peter D.; Mullan, Brian P.; Robb, Richard A.

    1999-05-01

    Subtraction ictal SPECT coregistered to MRI (SISCOM) has been shown to aid epileptogenic localization and improve surgical outcomes in partial epilepsy patients. This paper reports a new method of identifying significant areas of epileptogenic activation in the SISCOM subtraction image taking into account normal variation between sequential Tc-99m Ethyl Cysteinate Diethylester SPECT scans of single individuals. The method uses the AIR 3.0 nonlinear registration software to combine a group of subtraction images into a common anatomical framework. A map of the pixel intensity standard deviation values in the subtraction images is created, and this map is nonlinearly registered to a patient's SISCOM subtraction image. Pixels in the patient subtraction image may then be evaluated based upon the statistical characteristics of corresponding pixels in the atlas. Validation experiments were performed to verify that local image variances are not constant across the image and that nonlinear registration preserves local image variances. SISCOM images created with the voxel variance method were rated higher in quality than the conventional image variance method in images from fifteen patients. No difference in localization rate was observed between the voxel variance mapping and image variance methods. The voxel significance mapping method was shown to improve the quality of clinical SISCOM images without removing localizing information.

  2. Age-dependent change in biological characteristics of stem cells in radiation-induced mammary carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Yoshiya; Nishimura, Mayumi; Kakinuma, Shizuko; Imaoka, Tatsuhiko [National Institute of Radiological Sciences, Anagawa, Chiba (Japan); Yasukawa-Barnes, Jane; Gould, Michael N.; Clifton, Kelly H. [Univ. of Wisconsin, Department of Human Oncology, Madison, WI (United States)

    2003-07-01

    underlie the age-dependent susceptibility to radiation-induced breast cancer. (author)

  3. Age-dependent dichotomous effect of superoxide dismutase Ala16Val polymorphism on oxidized LDL levels.

    Science.gov (United States)

    Dedoussis, George V; Kanoni, Stavroula; Panagiotakos, Demosthenes B; Louizou, Eirini; Grigoriou, Efi; Chrysohoou, Christina; Pitsavos, Christos; Stefanadis, Christodoulos

    2008-02-29

    We investigated the association between superoxide dismutase (SOD) Ala16Val polymorphism and the levels of oxidized LDL lipoprotein-C (ox-LDL-C) in two age-different Greek cohorts. Four hundred fifteen middle-aged (n=147 females: 43.2+/-13 years, n=268 males: 43.3+/-14 years) Caucasian Greek subjects consisted the middle aged cohort. One hundred seventy five elderly (n=88 females: 79.9+/-4 years; n=87 males: 80.6+/-4 years) were selected from the elderly cohort. Genotype data were obtained for all of them. Multiple linear regression analysis, stratified by gender and adjusted for age, smoking habits and body mass index as covariates, showed higher ox-LDL-C levels for the middle aged men with the Val/Val genotype, compared to the other allele (Ala/Ala and Ala/Val) carriers (65.9+/-25.7 vs. 55.7+/-20.5 mg/dl; standardized beta coefficient=0.192, P=0.012). On the contrary, elderly women with the Val/Val genotype occurred with lower ox-LDL-C levels compared to the Ala/Ala or Ala/Val genotype (74.2+/-22.1 vs. 86.5+/-26.6 mg/dl; standardized beta coefficient= -0.269, P=0.015). The same trend was also recorded in elderly men, however without reaching statistical significance (standardized beta coefficient= -0.187, P=0.077). Moreover, elderly men and women with the Ala/Ala or Ala/Val genotype presented higher triglycerides levels compared to Val/Val (women: 145.2+/-68.7 vs. 114.3+/- 34.3 mg/dl, P= 0.027; men: 147.8+/-72.4 vs. 103.7 +/-38.0 mg/dl, P=0.002). Additionally, middle aged men with the Val/Val genotype had higher HDL-C levels compared to the Ala allele carriers. The results suggest that SOD Ala16Val polymorphism is an age-dependent modulator of ox-LDL-C levels in middle-aged men and elderly women.

  4. Age dependent T2 changes of bone marrow in pediatric wrist MRI

    Energy Technology Data Exchange (ETDEWEB)

    Shabshin, Nogah [Chaim Sheba Medical Center, Department of Diagnostic Imaging, Tel-HaShomer (Israel); Schweitzer, Mark E. [The Ottawa Hospital, The University of Ottawa, Department of Diagnostic Imaging, Ottawa (Canada)

    2009-12-15

    Hyperintensity of the bone marrow on fluid-sensitive sequences can be seen on magnetic resonance imaging (MRI) during childhood, even in the absence of bone pathology. They can be related to hematopoietic marrow, normal and abnormal bone remodeling. We sought to investigate whether hyper intensity of the bone marrow on MRI of the wrist is age-dependent and to evaluate if this signal follows a consistent age-related pattern. Thirty-one wrist 1.5 T MR images of children (7-18 years) without suspected bone pathology were evaluated for foci of hyperintense bone marrow seen on fluid-sensitive coronal sequences using a scale of 1-3. Correlation of frequency, location and intensity of these foci with age was obtained. Results were analyzed for distribution in single bones and in the following regions: distal forearm, first/second carpal rows, and metacarpal bases. A total of 448 bones were evaluated. Eighty-eight out of 448 (21 out of 31 wrists) showed hyperintense bone marrow seen on fluid-sensitive sequences. The distribution was: radius in 19, ulna in 19, first metacarpal base in 11, scaphoid in 9, lunate in 6, pisiform in 6, and fifth metacarpal base in 1. The involvement of the first and second carpal rows and the metacarpal bases was almost similar (13, 12, and 12 respectively). In the distal forearm, the intensity was similar to or higher than that in the wrist (2.2 vs. 2.0). Frequency decreased with age (100% at 7-9 and 25% at 16-18 years). Foci of hyperintense bone marrow seen on fluid-sensitive sequences can be seen on MRI of the wrist during childhood even without apparent symptoms. It shows a consistent pattern with maturation: frequency and intensity decrease and there is distal-to-proximal resolution. This may be a normal finding that may represent normal bone remodeling or decreasing hematopoietic marrow and should not be confused with pathological bone marrow edema. (orig.)

  5. Age dependent association of endometrial polyps with increased risk of cancer involvement

    Directory of Open Access Journals (Sweden)

    Martel Maritza

    2005-02-01

    Full Text Available Abstract Background Endometrial polyps (EMPs are commonly encountered in routine surgical pathology practice, but opinions differ on whether they are intrinsically a marker for concurrent or subsequent malignancy. The objectives of the present study are 1 to investigate the age-group in which EMP are most commonly encountered 2 to document the age-group in which EMP are most commonly associated with malignancies 3 To investigate whether the age of diagnosis of the various carcinoma subtypes in EMPs is congruent with published data on similar malignancies arising in non-polypoid endometrium and 4 To investigate whether the histologic subtype distribution of malignancies associated with EMPs are similar or different from the distribution of malignancies arising from non-polypoid endometrium based on published data. Patients and methods All cases of EMPs were retrieved from the files of Yale-New Haven Hospital for the period 1986–1995. The patients were divided into 5 age groups: Each group was further subclassified based on an association (or lack thereof of EMPs with endometrial carcinoma. Chi-square test was used to compare the proportion of malignancy associated EMPs between the age groups. Results We identified 513 EMPs, of which 209 (41% were from biopsy specimens and 304 (59% from hysterectomy specimens. Sixty six (13% of all EMPs were malignant. The 66 malignant EMPs included 58 endometrioid, 6 serous, 1 carcinosarcoma, and 1 clear cell carcinoma. In age group >35, only 1(2.5% of 40 EMPs was associated with endometrial malignancy. In contrast, 37(32% of 115 EMPs were associated with malignancy in the age group > 65. The frequency of malignant EMPs increased with age and reached statistical significance in the age group >65 (p Conclusions EMPs show statistically significant age dependent association with malignant tumor involvement. Careful search for malignancy, particularly in women with multiple risk factors is advised in daily practice

  6. Development of Chinese reference man deformable surface phantom and its application to the influence of physique on electromagnetic dosimetry.

    Science.gov (United States)

    Yu, D; Wang, M; Liu, Q

    2015-09-07

    A reference man is a theoretical individual that represents the average anatomical structure and physiological and metabolic features of a specific group of people and has been widely used in radiation safety research. With the help of an advantage in deformation, the present work proposed a Chinese reference man adult-male polygon-mesh surface phantom based on the Visible Chinese Human segment image dataset by surface rendering and deforming. To investigate the influence of physique on electromagnetic dosimetry in humans, a series of human phantoms with 10th, 50th and 90th body mass index and body circumference percentile physiques for Chinese adult males were further constructed by deforming the Chinese reference man surface phantom. All the surface phantoms were then voxelized to perform electromagnetic field simulation in a frequency range of 20 MHz to 3 GHz using the finite-difference time-domain method and evaluate the whole-body average and organ average specific absorption rate and the ratios of absorbed energy in skin, fat and muscle to the whole body. The results indicate thinner physique leads to higher WBSAR and the volume of subcutaneous fat, the penetration depth of the electromagnetic field in tissues and standing-wave occurrence may be the influence factors of physique on electromagnetic dosimetry.

  7. Monte Carlo study of voxel S factor dependence on tissue density and atomic composition

    Energy Technology Data Exchange (ETDEWEB)

    Amato, Ernesto, E-mail: eamato@unime.it [University of Messina, Department of Biomedical Sciences and of Morphologic and Functional Imaging, Section of Radiological Sciences, via Consolare Valeria, 1, I-98125 Messina (Italy); Italiano, Antonio [INFN – Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Messina (Italy); Baldari, Sergio [University of Messina, Department of Biomedical Sciences and of Morphologic and Functional Imaging, Section of Radiological Sciences, via Consolare Valeria, 1, I-98125 Messina (Italy)

    2013-11-21

    Voxel dosimetry is a common approach to the internal dosimetry of non-uniform activity distributions in nuclear medicine therapies with radiopharmaceuticals and in the estimation of the radiation hazard due to internal contamination of radionuclides. Aim of the present work is to extend our analytical approach for the calculation of voxel S factors to materials different from the soft tissue. We used a Monte Carlo simulation in GEANT4 of a voxelized region of each material in which the source of monoenergetic electrons or photons was uniformly distributed within the central voxel, and the energy deposition was scored over the surrounding 11×11×11 voxels. Voxel S factors were obtained for the following standard ICRP materials: Adipose tissue, Bone cortical, Brain, Lung, Muscle skeletal and Tissue soft with 1 g cm{sup −3} density. Moreover, we considered the standard ICRU materials: Bone compact and Muscle striated. Voxel S factors were represented as a function of the “normalized radius”, defined as the ratio between the source–target voxel distance and the voxel side. We found that voxel S factors and related analytical fit functions are mainly affected by the tissue density, while the material composition gives only a slight contribution to the difference between data series, which is negligible for practical purposes. Our results can help in broadening the dosimetric three-dimensional approach based on voxel S factors to other tissues where diagnostic and therapeutic radionuclides can be taken up and radiation can propagate.

  8. A custom-built PET phantom design for quantitative imaging of printed distributions

    Energy Technology Data Exchange (ETDEWEB)

    Markiewicz, P J; Angelis, G I; Kotasidis, F; Green, M; Matthews, J C [School of Cancer and Enabling Sciences, MAHSC, University of Manchester, Wolfson Molecular Imaging Centre, Manchester (United Kingdom); Lionheart, W R [School of Mathematics, Alan Turing Building, The University of Manchester (United Kingdom); Reader, A J, E-mail: p.markiewicz@manchester.ac.uk [Montreal Neurological Institute, McGill University, Montreal (Canada)

    2011-11-07

    This note presents a practical approach to a custom-made design of PET phantoms enabling the use of digital radioactive distributions with high quantitative accuracy and spatial resolution. The phantom design allows planar sources of any radioactivity distribution to be imaged in transaxial and axial (sagittal or coronal) planes. Although the design presented here is specially adapted to the high-resolution research tomograph (HRRT), the presented methods can be adapted to almost any PET scanner. Although the presented phantom design has many advantages, a number of practical issues had to be overcome such as positioning of the printed source, calibration, uniformity and reproducibility of printing. A well counter (WC) was used in the calibration procedure to find the nonlinear relationship between digital voxel intensities and the actual measured radioactive concentrations. Repeated printing together with WC measurements and computed radiography (CR) using phosphor imaging plates (IP) were used to evaluate the reproducibility and uniformity of such printing. Results show satisfactory printing uniformity and reproducibility; however, calibration is dependent on the printing mode and the physical state of the cartridge. As a demonstration of the utility of using printed phantoms, the image resolution and quantitative accuracy of reconstructed HRRT images are assessed. There is very good quantitative agreement in the calibration procedure between HRRT, CR and WC measurements. However, the high resolution of CR and its quantitative accuracy supported by WC measurements made it possible to show the degraded resolution of HRRT brain images caused by the partial-volume effect and the limits of iterative image reconstruction. (note)

  9. The UF/NCI family of hybrid computational phantoms representing the current US population of male and female children, adolescents, and adults—application to CT dosimetry

    Science.gov (United States)

    Geyer, Amy M.; O'Reilly, Shannon; Lee, Choonsik; Long, Daniel J.; Bolch, Wesley E.

    2014-09-01

    Substantial increases in pediatric and adult obesity in the US have prompted a major revision to the current UF/NCI (University of Florida/National Cancer Institute) family of hybrid computational phantoms to more accurately reflect current trends in larger body morphometry. A decision was made to construct the new library in a gridded fashion by height/weight without further reference to age-dependent weight/height percentiles as these become quickly outdated. At each height/weight combination, circumferential parameters were defined and used for phantom construction. All morphometric data for the new library were taken from the CDC NHANES survey data over the time period 1999-2006, the most recent reported survey period. A subset of the phantom library was then used in a CT organ dose sensitivity study to examine the degree to which body morphometry influences the magnitude of organ doses for patients that are underweight to morbidly obese in body size. Using primary and secondary morphometric parameters, grids containing 100 adult male height/weight bins, 93 adult female height/weight bins, 85 pediatric male height/weight bins and 73 pediatric female height/weight bins were constructed. These grids served as the blueprints for construction of a comprehensive library of patient-dependent phantoms containing 351 computational phantoms. At a given phantom standing height, normalized CT organ doses were shown to linearly decrease with increasing phantom BMI for pediatric males, while curvilinear decreases in organ dose were shown with increasing phantom BMI for adult females. These results suggest that one very useful application of the phantom library would be the construction of a pre-computed dose library for CT imaging as needed for patient dose-tracking.

  10. Custom molded thermal MRg-FUS phantom

    Science.gov (United States)

    Eames, Matthew D. C.; Snell, John W.; Hananel, Arik; Kassell, Neal F.

    2012-11-01

    This article describes a method for creating custom-molded thermal phantoms for use with MR-guided focused ultrasound systems. The method is defined here for intracranial applications, though it may be modified for other anatomical targets.

  11. Phantom cosmology without Big Rip singularity

    Energy Technology Data Exchange (ETDEWEB)

    Astashenok, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, 236041, 14, Nevsky st., Kaliningrad (Russian Federation); Nojiri, Shin' ichi, E-mail: nojiri@phys.nagoya-u.ac.jp [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Nagoya 464-8602 (Japan); Odintsov, Sergei D. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Institucio Catalana de Recerca i Estudis Avancats - ICREA and Institut de Ciencies de l' Espai (IEEC-CSIC), Campus UAB, Facultat de Ciencies, Torre C5-Par-2a pl, E-08193 Bellaterra (Barcelona) (Spain); Tomsk State Pedagogical University, Tomsk (Russian Federation); Yurov, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, 236041, 14, Nevsky st., Kaliningrad (Russian Federation)

    2012-03-23

    We construct phantom energy models with the equation of state parameter w which is less than -1, w<-1, but finite-time future singularity does not occur. Such models can be divided into two classes: (i) energy density increases with time ('phantom energy' without 'Big Rip' singularity) and (ii) energy density tends to constant value with time ('cosmological constant' with asymptotically de Sitter evolution). The disintegration of bound structure is confirmed in Little Rip cosmology. Surprisingly, we find that such disintegration (on example of Sun-Earth system) may occur even in asymptotically de Sitter phantom universe consistent with observational data. We also demonstrate that non-singular phantom models admit wormhole solutions as well as possibility of Big Trip via wormholes.

  12. Voxel-by-voxel correlations of perfusion, substrate, and metabolite signals in dynamic hyperpolarized (13) C imaging.

    Science.gov (United States)

    Lau, Justin Y C; Chen, Albert P; Gu, Yi-Ping; Cunningham, Charles H

    2016-08-01

    In this study, a mixture of pyruvic acid and the perfusion agent HP001 was co-polarized for simultaneous assessment of perfusion and metabolism in vivo. The pre-polarized mixture was administered to rats with subcutaneous MDA-MB-231 breast cancer xenografts and imaged using an interleaved sequence with designed spectral-spatial pulses and flyback echo-planar readouts. Voxel-by-voxel signal correlations from 10 animals (15 data sets) were analyzed for tumour, kidney, and muscle regions of interest. The relationship between perfusion and hyperpolarized signal was explored on a voxel-by-voxel basis in various metabolically active tissues, including tumour, healthy kidneys, and skeletal muscle. Positive pairwise correlations between lactate, pyruvate, and HP001 observed in all 10 tumours suggested that substrate delivery was the dominant factor limiting the conversion of pyruvate to lactate in the tumour model used in this study. On the other hand, in cases where conversion is the limiting factor, such as in healthy kidneys, both pyruvate and lactate can act as excellent perfusion markers. In intermediate cases between the two limits, such as in skeletal muscle, some perfusion information may be inferred from the (pyruvate + lactate) signal distribution. Co-administration of pyruvate with a dynamic nuclear polarization (DNP) perfusion agent is an effective approach for distinguishing between slow metabolism and poor perfusion and a practical strategy for lactate signal normalization to account for substrate delivery, especially in cases of rapid pyruvate-to-lactate conversion and in poorly perfused regions with inadequate pyruvate signal-to-noise ratio for reliable determination of the lactate-to-pyruvate ratio. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Comparing voxel-based iterative sensitivity and voxel-based morphometry to detect abnormalities in T2-weighted MRI.

    Science.gov (United States)

    Diaz-de-Grenu, Lara Z; Acosta-Cabronero, Julio; Williams, Guy B; Nestor, Peter J

    2014-10-15

    This study aimed to test the superiority proposed by Abbott et al. (2011) of their Voxel based iterative sensitivity (VBIS) method over Voxel Based Morphometry using T2-weighted images (T2-VBM), in detecting intensity changes in Alzheimer's disease (AD). A comparison was made first in simulated intensity lesions and then in AD patients. Intensity changes were evaluated in the whole-brain with VBIS and with a simple intensity-based approach and in specific tissue classes with the conventional VBM method of using tissue probability segments. Results showed that VBIS performed well in the simulated environment though it showed no superiority in detecting the lesion compared to the much simpler VBM approach. The VBIS method, however, failed to detect any meaningful signal intensity reduction in AD patient data. Moreover, its whole brain approach was contaminated by the excess cerebrospinal fluid signal (very bright on T2-weighted scans) in areas of maximal measurable atrophy (mesial temporal lobes); this gave rise to spurious signal intensity increases in these regions in AD. The same artefact was observed for both intensity-based methods but not with the conventional VBM approach of performing statistics on grey matter segments. In conclusion, no evidence was found to indicate that VBIS offers benefits over T2-VBM in AD, nor in simulation intensity lesions. The study highlights the necessity of empirically testing voxel-based analysis techniques rather than merely claiming superiority of one method over another on theoretical grounds.

  14. Development of realistic physical breast phantoms matched to virtual breast phantoms based on human subject data

    Energy Technology Data Exchange (ETDEWEB)

    Kiarashi, Nooshin [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Nolte, Adam C. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Sturgeon, Gregory M.; Ghate, Sujata V. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Segars, William P. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27708 (United States); Nolte, Loren W. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Samei, Ehsan [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, Duke University, Durham, North Carolina 27708 (United States); and others

    2015-07-15

    Purpose: Physical phantoms are essential for the development, optimization, and evaluation of x-ray breast imaging systems. Recognizing the major effect of anatomy on image quality and clinical performance, such phantoms should ideally reflect the three-dimensional structure of the human breast. Currently, there is no commercially available three-dimensional physical breast phantom that is anthropomorphic. The authors present the development of a new suite of physical breast phantoms based on human data. Methods: The phantoms were designed to match the extended cardiac-torso virtual breast phantoms that were based on dedicated breast computed tomography images of human subjects. The phantoms were fabricated by high-resolution multimaterial additive manufacturing (3D printing) technology. The glandular equivalency of the photopolymer materials was measured relative to breast tissue-equivalent plastic materials. Based on the current state-of-the-art in the technology and available materials, two variations were fabricated. The first was a dual-material phantom, the Doublet. Fibroglandular tissue and skin were represented by the most radiographically dense material available; adipose tissue was represented by the least radiographically dense material. The second variation, the Singlet, was fabricated with a single material to represent fibroglandular tissue and skin. It was subsequently filled with adipose-equivalent materials including oil, beeswax, and permanent urethane-based polymer. Simulated microcalcification clusters were further included in the phantoms via crushed eggshells. The phantoms were imaged and characterized visually and quantitatively. Results: The mammographic projections and tomosynthesis reconstructed images of the fabricated phantoms yielded realistic breast background. The mammograms of the phantoms demonstrated close correlation with simulated mammographic projection images of the corresponding virtual phantoms. Furthermore, power

  15. Phantom Limb Pain: Mechanisms and Treatment Approaches

    Directory of Open Access Journals (Sweden)

    Bishnu Subedi

    2011-01-01

    Full Text Available The vast amount of research over the past decades has significantly added to our knowledge of phantom limb pain. Multiple factors including site of amputation or presence of preamputation pain have been found to have a positive correlation with the development of phantom limb pain. The paradigms of proposed mechanisms have shifted over the past years from the psychogenic theory to peripheral and central neural changes involving cortical reorganization. More recently, the role of mirror neurons in the brain has been proposed in the generation of phantom pain. A wide variety of treatment approaches have been employed, but mechanism-based specific treatment guidelines are yet to evolve. Phantom limb pain is considered a neuropathic pain, and most treatment recommendations are based on recommendations for neuropathic pain syndromes. Mirror therapy, a relatively recently proposed therapy for phantom limb pain, has mixed results in randomized controlled trials. Most successful treatment outcomes include multidisciplinary measures. This paper attempts to review and summarize recent research relative to the proposed mechanisms of and treatments for phantom limb pain.

  16. Voxelization Algorithms for Geospatial Applications: Computational methods for voxelating spatial datasets of 3D city models containing 3D surface, curve and point data models

    NARCIS (Netherlands)

    Nourian Ghadikolaee, P.; Goncalves, R.; Zlatanova, S.; Arroyo Ohori, G.A.K.; Vu Vo, A.

    2016-01-01

    Voxel representations have been used for years in scientific computation and medical imaging. The main focus of our research is to provide easy access to methods for making large-scale voxel models of built environment for environmental modelling studies while ensuring they are spatially correct, me

  17. Desarrollo de un programa de simulación basado en el método de Montecarlo para el cálculo de dosis con maniquíes divididos en voxels. Aplicaciones en tomografía computarizada

    OpenAIRE

    Salvadó Artells, Marçal

    2004-01-01

    Among the different radiodiagnostic techniques, computed tomography (CT) represents the major contribution to the collective dose. In order to have available a tool to assess and ascertain the imparted dose upon CT examinations, we have developed and validated a method to calculate radiation absorbed dose in CT examinations from images of phantoms and standard patients by using a voxel-based Monte Carlo simulation method.Simulations and measurements of radiation dose were conducted in air, wi...

  18. A voxel-based approach to gray matter asymmetries.

    Science.gov (United States)

    Luders, E; Gaser, C; Jancke, L; Schlaug, G

    2004-06-01

    Voxel-based morphometry (VBM) was used to analyze gray matter (GM) asymmetries in a large sample (n = 60) of male and female professional musicians with and without absolute pitch (AP). We chose to examine these particular groups because previous studies using traditional region-of-interest (ROI) analyses have shown differences in hemispheric asymmetry related to AP and gender. Voxel-based methods may have advantages over traditional ROI-based methods since the analysis can be performed across the whole brain with minimal user bias. After determining that the VBM method was sufficiently sensitive for the detection of differences in GM asymmetries between groups, we found that male AP musicians were more leftward lateralized in the anterior region of the planum temporale (PT) than male non-AP musicians. This confirmed the results of previous studies using ROI-based methods that showed an association between PT asymmetry and the AP phenotype. We further observed that male non-AP musicians revealed an increased leftward GM asymmetry in the postcentral gyrus compared to female non-AP musicians, again corroborating results of a previously published study using ROI-based methods. By analyzing hemispheric GM differences across our entire sample, we were able to partially confirm findings of previous studies using traditional morphometric techniques, as well as more recent, voxel-based analyses. In addition, we found some unusually pronounced GM asymmetries in our musician sample not previously detected in subjects unselected for musical training. Since we were able to validate gender- and AP-related brain asymmetries previously described using traditional ROI-based morphometric techniques, the results of our analyses support the use of VBM for examinations of GM asymmetries.

  19. A radioactive seed implant on a rabbit's liver following a voxel model representation for dosimetric proposals

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Tarcisio P.R.; Andrade, Joao Paulo Lopes de; Costa, Igor Temponi; Teixeira, Cleuza H. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares]. E-mail: campos@nuclear.ufmg

    2005-07-01

    Animal models have been used in experimentation with ionizing radiation. The evaluation of the energy absorbed per unit tissue mass in vivo transported by nuclear particles is a task to be performed before experimentation. Stochastic or deterministic methodology can be applied, however the dosimetric protocols applied in radiotherapy center cannot be applied directly due to the inherent small geometry and chemical composition of the animal distinct from human. The present article addresses a method in development that will predict the dose distribution into the rabbit thorax based on the solution of the transport phenomena in a voxel model. The model will be applied to simulate a seed implant experiment on a rabbit. Herein, the construction of the three-dimensional voxel model anthropomorphic -anthropometrics to the rabbit is presented. The model is assembling from a set of computer tomography of the rabbit. The computational phantom of the thorax starts at the digitalisation of the CT images, tissue definition, and color image representation of each tissue and organ. The chemical composition and mass density of each tissue is evaluated as similar date presented by ICRU-44. To treat the images, a code namely SISCODES, developed in house, was used. The in vivo experiment that will be simulated is also described. That is a implant of five seeds of 1.6x2 mm performed in a rabbit's liver. The perspective of this work is the application of the model in dosimetric studies predicting the dose distribution around the seed's implanted in vivo experiments. (author)

  20. Age dependent nitro-oxidative load and melatonin receptor expression in the spleen and immunity of goat Capra hircus.

    Science.gov (United States)

    Singh, Amaresh Kumar; Haldar, Chandana

    2014-12-01

    The decline in the plasma level of melatonin has been associated with increased oxidative stress in the physiological system while aging. The increased levels of oxidants are known to augment the nitro-oxidative stress, which induces the apoptotic factors in lymphoid organs leading to age dependent immunosenescence. There are no reports to date that can suggest how the age dependent nitro-oxidative stress can influence the melatonin membrane MT1/MT2R expression and immune status of any small ruminant. In the present study, we noted the expression of melatonin receptors MT1R and MT2R and inducible nitric oxide synthase (iNOS) along with the apoptotic markers (viz. Bcl-2, Bax and Pro-caspase-3) in the spleen of young, middle-aged and old-aged Indian goat Capra hircus. The lymphocyte proliferation was also recorded along with the total nitrite and nitrate ion concentration (NOx) in the spleen and plasma. An age dependent decline in MT1R and MT2R expressions and lymphocyte proliferation with increased level of reactive nitrogen species (RNS) and iNOS expression was noted. An increased Bax/Bcl-2 ratio and a decreased Pro-caspase-3 expression were observed in the spleen of goat with an age dependent decline in the peripheral melatonin level. This decline in melatonin along with reduced melatonin receptor (MT1/MT2) expression and elevated RNS level in the spleen with aging might have an important role in the regulation of immune function of goats. Our observations suggest that the age-associated immunosenescence observed in goats can be a consequence of declining melatonin and its receptor expression and induction of apoptotic factors influenced by the increased RNS level that deteriorates the proper functioning of the spleen.

  1. Vessel-guided airway tree segmentation: A voxel classification approach

    DEFF Research Database (Denmark)

    Ashraf, Haseem; Pedersen, Jesper J H; Lo, Pechin Chien Pau;

    2010-01-01

    This paper presents a method for airway tree segmentation that uses a combination of a trained airway appearance model, vessel and airway orientation information, and region growing. We propose a voxel classification approach for the appearance model, which uses a classifier that is trained...... method is evaluated on 250 low dose computed tomography images from a lung cancer screening trial. Our experiments showed that applying the region growing algorithm on the airway appearance model produces more complete airway segmentations, leading to on average 20% longer trees, and 50% less leakage...

  2. Microsurgeons do better--tactile training might prevent the age-dependent decline of the sensibility of the hand.

    Science.gov (United States)

    Schmauss, Daniel; Megerle, Kai; Weinzierl, Andrea; Agua, Kariem; Cerny, Michael; Schmauss, Verena; Lohmeyer, Joern A; Machens, Hans-Guenther; Erne, Holger

    2015-12-01

    Recent data demonstrate that the normal sensibility of the hand seems to be age-dependent with the best values in the third decade and a consecutive deterioration afterwards. However, it is not clear if long-term tactile training might prevent this age-dependent decline. We evaluated sensibility of the hand in 125 surgeons aged between 26 and 75 years who perform microsurgical operations, thereby undergoing regular tactile training. We examined sensibility of the radial digital nerve of the index finger (N3) and the ulnar digital nerve of the small finger (N10) using static and moving two-point discrimination (2PD) tests and compared the results to 154 age-matched individuals without specific long-term tactile training. We found significantly lower static and moving 2PD values for the sixth, seventh, and eighth decade of life in the microsurgery group compared to the control group (p < 0.05). This study demonstrates that long-term tactile training might prevent the known age-dependent decline of the sensibility of the hand.

  3. An MRI phantom using carrageenan gel

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Hirokazu; Kuroda, Masahiro; Yoshimura, Koichi; Kawasaki, Shoji; Yamamoto, Naotake; Tanaka, Akio; Hiraki, Yoshio [Okayama Univ. (Japan). School of Medicine; Uchida, Nobue; Sugimura, Kazuro

    2000-12-01

    We have developed a new solid type carrageenan gel phantom. The ingredients of the new gel are carrageenan, manganese chloride, sodium chloride, sodium azide, and water. The gel phantom has sufficient strength to form a torso without the use of a reinforcing agent. A phantom of a desired shape can be created by pouring a hot solution of carrageenan into a mold. The phantom can then be cut easily with a knife and trimmed into the desired shape. The recommended concentrations of the ingredients are; 5 wt% carrageenan, 0.2 mM MnCl{sub 2}, 0.19 wt% NaCl, 0.1 wt% NaN{sub 3}, with the remainder being water. T{sub 2} and T{sub 1} of this phantom at 1.5 T are 84.9 ms and 429 ms respectively. The conductivity and relative dielectric constant at 63.8 MHz are 0.769 S/m and 81.4 respectively. (author)

  4. Pharmacological interventions for phantom limb pain

    Institute of Scientific and Technical Information of China (English)

    FANG Jun; LIAN Yan-hong; XIE Kang-jie; CAI Shu-nü

    2013-01-01

    Objective To review the mechanisms and current clinical application of pharmacological interventions for phantom limb pain.Data sources Both Chinese and English language literatures were searched using MEDLINE (1982-2011),Pubmed (1982-2011) and the Index of Chinese Language Literature (1982-2011).Study selection Data from published articles about pharmacological management of phantom limb pain in recent domestic and foreign literature were selected.Data extraction Data were mainly extracted from 96 articles which are listed in the reference section of this review.Results By reviewing the mechanisms and current clinical application of pharmacological interventions for phantom limb pain,including anticonvulsants,antidepressants,local anaesthetics,N-methyl-D-aspartate receptor antagonists,non-steroidal anti-inflammatory drugs,tramadol,opioids,calcitonin,capsaicin,beta-adrenergic blockers,clonidine,muscle relaxants,and emerging drugs,we examined the efficacy and safety of these medications,outlined the limitations and future directions.Conclusions Although there is lack of evidence-based consensus guidelines for the pharmacological management of phantom limb pain,we recommend tricyclic antidepressants,gabapentin,tramadol,opioids,local anaesthetics and N-methyl-D-aspartate receptor antagonists as the rational options for the treatment of phantom limb pain.

  5. Adjustable fetal phantom for pulse oximetry

    Science.gov (United States)

    Stubán, Norbert; Niwayama, Masatsugu

    2009-05-01

    As the measuring head of a fetal pulse oximeter must be attached to the head of the fetus inside the mother's uterus during labor, testing, and developing of fetal pulse oximeters in real environment have several difficulties. A fetal phantom could enable evaluation of pulse oximeters in a simulated environment without the restrictions and difficultness of medical experiments in the labor room. Based on anatomic data we developed an adjustable fetal head phantom with three different tissue layers and artificial arteries. The phantom consisted of two arteries with an inner diameter of 0.2 and 0.4 mm. An electronically controlled pump produced pulse waves in the arteries. With the phantom we investigated the sensitivity of a custom-designed wireless pulse oximeter at different pulsation intensity and artery diameters. The results showed that the oximeter was capable of identifying 4% and 2% changes in diameter between the diastolic and systolic point in arteries of over 0.2 and 0.4 mm inner diameter, respectively. As the structure of the phantom is based on reported anatomic values, the results predict that the investigated custom-designed wireless pulse oximeter has sufficient sensitivity to detect the pulse waves and to calculate the R rate on the fetal head.

  6. Voxelization algorithms for geospatial applications: Computational methods for voxelating spatial datasets of 3D city models containing 3D surface, curve and point data models.

    Science.gov (United States)

    Nourian, Pirouz; Gonçalves, Romulo; Zlatanova, Sisi; Ohori, Ken Arroyo; Vu Vo, Anh

    2016-01-01

    Voxel representations have been used for years in scientific computation and medical imaging. The main focus of our research is to provide easy access to methods for making large-scale voxel models of built environment for environmental modelling studies while ensuring they are spatially correct, meaning they correctly represent topological and semantic relations among objects. In this article, we present algorithms that generate voxels (volumetric pixels) out of point cloud, curve, or surface objects. The algorithms for voxelization of surfaces and curves are a customization of the topological voxelization approach [1]; we additionally provide an extension of this method for voxelization of point clouds. The developed software has the following advantages:•It provides easy management of connectivity levels in the resulting voxels.•It is not dependant on any external library except for primitive types and constructs; therefore, it is easy to integrate them in any application.•One of the algorithms is implemented in C++ and C for platform independence and efficiency.

  7. Fast voxel and polygon ray-tracing algorithms in intensity modulated radiation therapy treatment planning.

    Science.gov (United States)

    Fox, Christopher; Romeijn, H Edwin; Dempsey, James F

    2006-05-01

    We present work on combining three algorithms to improve ray-tracing efficiency in radiation therapy dose computation. The three algorithms include: An improved point-in-polygon algorithm, incremental voxel ray tracing algorithm, and stereographic projection of beamlets for voxel truncation. The point-in-polygon and incremental voxel ray-tracing algorithms have been used in computer graphics and nuclear medicine applications while the stereographic projection algorithm was developed by our group. These algorithms demonstrate significant improvements over the current standard algorithms in peer reviewed literature, i.e., the polygon and voxel ray-tracing algorithms of Siddon for voxel classification (point-in-polygon testing) and dose computation, respectively, and radius testing for voxel truncation. The presented polygon ray-tracing technique was tested on 10 intensity modulated radiation therapy (IMRT) treatment planning cases that required the classification of between 0.58 and 2.0 million voxels on a 2.5 mm isotropic dose grid into 1-4 targets and 5-14 structures represented as extruded polygons (a.k.a. Siddon prisms). Incremental voxel ray tracing and voxel truncation employing virtual stereographic projection was tested on the same IMRT treatment planning cases where voxel dose was required for 230-2400 beamlets using a finite-size pencil-beam algorithm. Between a 100 and 360 fold cpu time improvement over Siddon's method was observed for the polygon ray-tracing algorithm to perform classification of voxels for target and structure membership. Between a 2.6 and 3.1 fold reduction in cpu time over current algorithms was found for the implementation of incremental ray tracing. Additionally, voxel truncation via stereographic projection was observed to be 11-25 times faster than the radial-testing beamlet extent approach and was further improved 1.7-2.0 fold through point-classification using the method of translation over the cross product technique.

  8. Confronting Phantom Dark Energy with Observations

    CERN Document Server

    Wang, Pao-Yu; Chen, Pisin

    2012-01-01

    We confront two types of phantom dark energy potential with observational data. The models we consider are the power-law potential, $V\\propto {\\phi}^{\\mu}$, and the exponential potential, $V\\propto \\exp({\\lambda}{\\phi}/{M_P})$. We fit the models to the latest observations from SN-Ia, CMB and BAO, and obtain tight constraints on parameter spaces. Furthermore, we apply the goodness-of-fit and the information criteria to compare the fitting results from phantom models with that from the cosmological constant and the quintessence models presented in our previous work. The results show that the cosmological constant is statistically most preferred, while the phantom dark energy fits slightly better than the quintessence does.

  9. Single Voxel Proton Spectroscopy for Neurofeedback at 7 Tesla

    Directory of Open Access Journals (Sweden)

    Mark A. Elliott

    2011-09-01

    Full Text Available Echo-planar imaging (EPI in fMRI is regularly used to reveal BOLD activation in presubscribed regions of interest (ROI. The response is mediated by relative changes in T2* which appear as changes in the image pixel intensities. We have proposed an application of functional single-voxel proton spectroscopy (fSVPS for real-time studies at ultra-high MR field which can be comparable to the EPI BOLD fMRI technique. A spin-echo SVPS protocol without water suppression was acquired with 310 repetitions on a 7T Siemens MR scanner (TE/TR = 20/1000 ms, flip angle α = 90°, voxel size 10 × 10 × 10 mm3. Transmitter reference voltage was optimized for the voxel location. Spectral processing of the water signal free induction decay (FID using log-linear regression was used to estimate the T2* change between rest and activation of a functional task. The FID spectrum was filtered with a Gaussian window around the water peak, and log-linear regression was optimized for the particular ROI by adoption of the linearization length. The spectroscopic voxel was positioned on an ROI defined from a real-time fMRI EPI BOLD localizer. Additional online signal processing algorithms performed signal drift removal (exponential moving average, despiking and low-pass filtering (modified Kalman filter and, finally, the dynamic feedback signal normalization. Two functional tasks were used to estimate the sensitivity of the SVPS method compared to BOLD signal changes, namely the primary motor cortex (PMC, left hand finger tapping and visual cortex (VC, blinking checkerboard. Four healthy volunteers performed these tasks and an additional session using real-time signal feedback modulating their activation level of the PMC. Results show that single voxel spectroscopy is able to provide a good and reliable estimation of the BOLD signal changes. Small data size and FID signal processing instead of processing entire brain volumes as well as more information revealed from the

  10. Single Voxel Proton Spectroscopy for Neurofeedback at 7 Tesla.

    Science.gov (United States)

    Koush, Yury; Elliott, Mark A; Mathiak, Klaus

    2011-09-01

    Echo-planar imaging (EPI) in fMRI is regularly used to reveal BOLD activation in presubscribed regions of interest (ROI). The response is mediated by relative changes in T2* which appear as changes in the image pixel intensities. We have proposed an application of functional single-voxel proton spectroscopy (fSVPS) for real-time studies at ultra-high MR field which can be comparable to the EPI BOLD fMRI technique. A spin-echo SVPS protocol without water suppression was acquired with 310 repetitions on a 7T Siemens MR scanner (TE/TR = 20/1000 ms, flip angle α = 90°, voxel size 10 × 10 × 10 mm(3)). Transmitter reference voltage was optimized for the voxel location. Spectral processing of the water signal free induction decay (FID) using log-linear regression was used to estimate the T2* change between rest and activation of a functional task. The FID spectrum was filtered with a Gaussian window around the water peak, and log-linear regression was optimized for the particular ROI by adoption of the linearization length. The spectroscopic voxel was positioned on an ROI defined from a real-time fMRI EPI BOLD localizer. Additional online signal processing algorithms performed signal drift removal (exponential moving average), despiking and low-pass filtering (modified Kalman filter) and, finally, the dynamic feedback signal normalization. Two functional tasks were used to estimate the sensitivity of the SVPS method compared to BOLD signal changes, namely the primary motor cortex (PMC, left hand finger tapping) and visual cortex (VC, blinking checkerboard). Four healthy volunteers performed these tasks and an additional session using real-time signal feedback modulating their activation level of the PMC. Results show that single voxel spectroscopy is able to provide a good and reliable estimation of the BOLD signal changes. Small data size and FID signal processing instead of processing entire brain volumes as well as more information revealed from the acquired total

  11. WE-D-BRE-06: Quantification of Dose-Response for High Grade Esophagtis Patients Using a Novel Voxel-To-Voxel Method

    Energy Technology Data Exchange (ETDEWEB)

    Niedzielski, J; Martel, M; Tucker, S; Gomez, D; Court, L [MD Anderson Cancer Center, Houston, TX (United States); Univ. of Texas-Graduate School of Biomedical Sciences, Houston, TX (United States); Yang, J; Briere, T [MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-15

    Purpose: Radiation induces an inflammatory response in the esophagus, discernible on CT studies. This work objectively quantifies the voxel esophageal radiation-response for patients with acute esophagitis. This knowledge is an important first-step towards predicting the effect of complex dose distributions on patient esophagitis symptoms. Methods: A previously validated voxel-based methodology of quantifying radiation esophagitis severity was used to identify the voxel dose-response for 18 NSCLC patients with severe esophagitis (CTCAE grading criteria, grade2 or higher). The response is quantified as percent voxel volume change for a given dose. During treatment (6–8 weeks), patients had weekly 4DCT studies and esophagitis scoring. Planning CT esophageal contours were deformed to each weekly CT using a demons DIR algorithm. An algorithm using the Jacobian Map from the DIR of the planning CT to all weekly CTs was used to quantify voxel-volume change, along with corresponding delivered voxel dose, to the planning voxel. Dose for each voxel for each time-point was calculated on each previous weekly CT image, and accumulated using DIR. Thus, for each voxel, the volume-change and delivered dose was calculated for each time-point. The data was binned according to when the volume-change first increased by a threshold volume (10%–100%, in 10% increments), and the average delivered dose calculated for each bin. Results: The average dose resulting in a voxel volume increase of 10–100% was 21.6 to 45.9Gy, respectively. The mean population dose to give a 50% volume increase was 36.3±4.4Gy, (range:29.8 to 43.5Gy). The average week of 50% response was 4.1 (range:4.9 to 2.8 weeks). All 18 patients showed similar dose to first response curves, showing a common trend in the initial inflammatoryresponse. Conclusion: We extracted the dose-response curve of the esophagus on a voxel-to-voxel level. This may be useful for estimating the esophagus response (and patient symptoms

  12. Technical Note: Phantom study to evaluate the dose and image quality effects of a computed tomography organ-based tube current modulation technique

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, Diksha; Schmidt, Taly Gilat, E-mail: taly.gilat-schmidt@marquette.edu [Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin 53201 (United States); Crotty, Dominic J.; Stevens, Grant M. [GE Healthcare, Waukesha, Wisconsin 53188 (United States)

    2015-11-15

    Purpose: This technical note quantifies the dose and image quality performance of a clinically available organ-dose-based tube current modulation (ODM) technique, using experimental and simulation phantom studies. The investigated ODM implementation reduces the tube current for the anterior source positions, without increasing current for posterior positions, although such an approach was also evaluated for comparison. Methods: Axial CT scans at 120 kV were performed on head and chest phantoms on an ODM-equipped scanner (Optima CT660, GE Healthcare, Chalfont St. Giles, England). Dosimeters quantified dose to breast, lung, heart, spine, eye lens, and brain regions for ODM and 3D-modulation (SmartmA) settings. Monte Carlo simulations, validated with experimental data, were performed on 28 voxelized head phantoms and 10 chest phantoms to quantify organ dose and noise standard deviation. The dose and noise effects of increasing the posterior tube current were also investigated. Results: ODM reduced the dose for all experimental dosimeters with respect to SmartmA, with average dose reductions across dosimeters of 31% (breast), 21% (lung), 24% (heart), 6% (spine), 19% (eye lens), and 11% (brain), with similar results for the simulation validation study. In the phantom library study, the average dose reduction across all phantoms was 34% (breast), 20% (lung), 8% (spine), 20% (eye lens), and 8% (brain). ODM increased the noise standard deviation in reconstructed images by 6%–20%, with generally greater noise increases in anterior regions. Increasing the posterior tube current provided similar dose reduction as ODM for breast and eye lens, increased dose to the spine, with noise effects ranging from 2% noise reduction to 16% noise increase. At noise equal to SmartmA, ODM increased the estimated effective dose by 4% and 8% for chest and head scans, respectively. Increasing the posterior tube current further increased the effective dose by 15% (chest) and 18% (head

  13. Standard operating procedure to prepare agar phantoms

    Science.gov (United States)

    Souza, R. M.; Santos, T. Q.; Oliveira, D. P.; Souza, R. M.; Alvarenga, A. V.; Costa-Felix, R. P. B.

    2016-07-01

    Agar phantoms are widely used as soft tissue mimics and some preparation techniques are described in the literature. There are also standards that describe the recipe of a soft tissue mimicking material (TMM). However some details of manufacture process are not clearly defined. The standardization of the phantom's preparation can produce a metrological impact on the results of the acoustic properties measured. In this direction, this paper presents a standard operating procedure (SOP) to prepare the agar TMM described on the IEC 60601-237.

  14. A 4D biomechanical lung phantom for joint segmentation/registration evaluation

    Science.gov (United States)

    Markel, Daniel; Levesque, Ives; Larkin, Joe; Léger, Pierre; El Naqa, Issam

    2016-10-01

    At present, there exists few openly available methods for evaluation of simultaneous segmentation and registration algorithms. These methods allow for a combination of both techniques to track the tumor in complex settings such as adaptive radiotherapy. We have produced a quality assurance platform for evaluating this specific subset of algorithms using a preserved porcine lung in such that it is multi-modality compatible: positron emission tomography (PET), computer tomography (CT) and magnetic resonance imaging (MRI). A computer controlled respirator was constructed to pneumatically manipulate the lungs in order to replicate human breathing traces. A registration ground truth was provided using an in-house bifurcation tracking pipeline. Segmentation ground truth was provided by synthetic multi-compartment lesions to simulate biologically active tumor, background tissue and a necrotic core. The bifurcation tracking pipeline results were compared to digital deformations and used to evaluate three registration algorithms, Diffeomorphic demons, fast-symmetric forces demons and MiMVista’s deformable registration tool. Three segmentation algorithms the Chan Vese level sets method, a Hybrid technique and the multi-valued level sets algorithm. The respirator was able to replicate three seperate breathing traces with a mean accuracy of 2-2.2%. Bifurcation tracking error was found to be sub-voxel when using human CT data for displacements up to 6.5 cm and approximately 1.5 voxel widths for displacements up to 3.5 cm for the porcine lungs. For the fast-symmetric, diffeomorphic and MiMvista registration algorithms, mean geometric errors were found to be 0.430+/- 0.001 , 0.416+/- 0.001 and 0.605+/- 0.002 voxels widths respectively using the vector field differences and 0.4+/- 0.2 , 0.4+/- 0.2 and 0.6+/- 0.2 voxel widths using the bifurcation tracking pipeline. The proposed phantom was found sufficient for accurate evaluation of registration and segmentation algorithms

  15. Static resistivity image of a cubic saline phantom in magnetic resonance electrical impedance tomography (MREIT).

    Science.gov (United States)

    Lee, Byung Il; Oh, Suk Hoon; Woo, Eung Je; Lee, Soo Yeol; Cho, Min Hyeong; Kwon, Ohin; Seo, Jin Keun; Baek, Woon Sik

    2003-05-01

    In magnetic resonance electrical impedance tomography (MREIT) we inject currents through electrodes placed on the surface of a subject and try to reconstruct cross-sectional resistivity (or conductivity) images using internal magnetic flux density as well as boundary voltage measurements. In this paper we present a static resistivity image of a cubic saline phantom (50 x 50 x 50 mm3) containing a cylindrical sausage object with an average resistivity value of 123.7 ohms cm. Our current MREIT system is based on an experimental 0.3 T MRI scanner and a current injection apparatus. We captured MR phase images of the phantom while injecting currents of 28 mA through two pairs of surface electrodes. We computed current density images from magnetic flux density images that are proportional to the MR phase images. From the current density images and boundary voltage data we reconstructed a cross-sectional resistivity image within a central region of 38.5 x 38.5 mm2 at the middle of the phantom using the J-substitution algorithm. The spatial resolution of the reconstructed image was 64 x 64 and the reconstructed average resistivity of the sausage was 117.7 ohms cm. Even though the error in the reconstructed average resistivity value was small, the relative L2-error of the reconstructed image was 25.5% due to the noise in measured MR phase images. We expect improvements in the accuracy by utilizing an MRI scanner with higher SNR and increasing the size of voxels scarifying the spatial resolution.

  16. Poster — Thur Eve — 71: A 4D Multimodal Lung Phantom for Regmentation Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Markel, D [McGill University, Physics, Montreal QC (Canada); Levesque, I R [McGill University, Oncology, Montreal QC (Canada); Research Institute of the McGill University Health Centre, Montreal, QC (Canada); El Naqa, I [McGill University, Physics, Montreal QC (Canada); McGill University, Oncology, Montreal QC (Canada)

    2014-08-15

    Segmentation and registration of medical imaging data are two processes that can be integrated (a process termed regmentation) to iteratively reinforce each other, potentially improving efficiency and overall accuracy. A significant challenge is presented when attempting to validate the joint process particularly with regards to minimizing geometric uncertainties associated with the ground truth while maintaining anatomical realism. This work demonstrates a 4D MRI, PET, and CT compatible tissue phantom with a known ground truth for evaluating registration and segmentation accuracy. The phantom consists of a preserved swine lung connected to an air pump via a PVC tube for inflation. Mock tumors were constructed from sea sponges contained within two vacuum-sealed compartments with catheters running into each one for injection of radiotracer solution. The phantom was scanned using a GE Discovery-ST PET/CT scanner and a 0.23T Phillips MRI, and resulted in anatomically realistic images. A bifurcation tracking algorithm was implemented to provide a ground truth for evaluating registration accuracy. This algorithm was validated using known deformations of up to 7.8 cm using a separate CT scan of a human thorax. Using the known deformation vectors to compare against, 76 bifurcation points were selected. The tracking accuracy was found to have maximum mean errors of −0.94, 0.79 and −0.57 voxels in the left-right, anterior-posterior and inferior-superior directions, respectively. A pneumatic control system is under development to match the respiratory profile of the lungs to a breathing trace from an individual patient.

  17. Ultrasonographic Quantification of Fat Content in Fatty Liver Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Il Young; Kim, Pyo Nyun; Joo, Gyung Soo; Kim, Ho Jung; Kim, Young Beom; Lee, Byoung Ho [Soonchunhyang University College of Medicine, Seoul (Korea, Republic of)

    1995-06-15

    Assuming that the fat content of certain tissue might be quantified by measurirrg the ultrasound echo level, we analyzed the ultrasound histograms obtained from the fatty liver phantoms that contained various amount of fat. Various amount of margarine(Mazola. Cliff wood. USA) was mixed with 2% of agarin solution state to produce fatty liver phantoms that contained 5, 10, 20, 30 and 40% of fat. We obtained ultrasound histogram from each fatty liver phantom in gel state. We used 2% agar gel as a control. The ultrasound histograms from the control phantom showed gradual increase in echo level as the depth from the surface increased. The echo level from the phantom that contained 5% of fat showed gradual increase and subsequent decrease with the peak echo level at the depth of 3cm. The echo levels from the phantoms that contained more in 5% of fat gradually decreased as the depth from the surface increased; the change becoming more pronounced as the fat content of the phantom increased. The echo levels measured at the depth of 1cm were 9.3(control), 29.6(5%phantom), 3l.3 (10% phantom), 26.3 (20% phantom), l8.8 (30% phantom), and l6dB (40% phantom). Fat content of fatty phantoms can not be quantified by measuring only echo level. Simultaneous measurement of attenuation of ultrasound, which is not easy to do and not done in this study, is prerequisite to quantify fat content

  18. Analysis of multiplex gene expression maps obtained by voxelation

    Directory of Open Access Journals (Sweden)

    Smith Desmond J

    2009-04-01

    Full Text Available Abstract Background Gene expression signatures in the mammalian brain hold the key to understanding neural development and neurological disease. Researchers have previously used voxelation in combination with microarrays for acquisition of genome-wide atlases of expression patterns in the mouse brain. On the other hand, some work has been performed on studying gene functions, without taking into account the location information of a gene's expression in a mouse brain. In this paper, we present an approach for identifying the relation between gene expression maps obtained by voxelation and gene functions. Results To analyze the dataset, we chose typical genes as queries and aimed at discovering similar gene groups. Gene similarity was determined by using the wavelet features extracted from the left and right hemispheres averaged gene expression maps, and by the Euclidean distance between each pair of feature vectors. We also performed a multiple clustering approach on the gene expression maps, combined with hierarchical clustering. Among each group of similar genes and clusters, the gene function similarity was measured by calculating the average gene function distances in the gene ontology structure. By applying our methodology to find similar genes to certain target genes we were able to improve our understanding of gene expression patterns and gene functions. By applying the clustering analysis method, we obtained significant clusters, which have both very similar gene expression maps and very similar gene functions respectively to their corresponding gene ontologies. The cellular component ontology resulted in prominent clusters expressed in cortex and corpus callosum. The molecular function ontology gave prominent clusters in cortex, corpus callosum and hypothalamus. The biological process ontology resulted in clusters in cortex, hypothalamus and choroid plexus. Clusters from all three ontologies combined were most prominently expressed in

  19. The influence of HIV infection on the age dependence of squamous cell carcinoma of the skin in South Africa

    Directory of Open Access Journals (Sweden)

    B L Diffey

    2017-02-01

    Full Text Available Background. Cancer incidence typically increases with age, but it is not known whether ethnic characteristics influence the age dependence of squamous cell carcinoma of the skin (SCC. Objectives. (i To determine the age dependence of SCC in the black African, coloured and white population groups of South Africa (SA; and (ii to show whether any differences in the rate of change of age dependence could be influenced by diversity in behaviour and lifestyle, especially with regard to the prevalence of HIV infection, rather than by a fundamental variation in cancer biology between the populations. Methods. Linear regression analysis was applied to the logarithm of the age-specific incidence rates for SCC v. the logarithm of age between 35 and 74 years. The slopes of the regression (age exponent were compared for each subset of gender, population group and year of diagnosis (between 2000 and 2010. Results. The most notable feature was the low value of the age exponent in both male and female black African compared with the white and coloured populations. This finding could be explained in part by the difference in the prevalence of HIV infection in the black African population group compared with the white and coloured population groups. Conclusions. The prevalence of HIV infection in black Africans in SA tends to decrease the apparent age component in SCC compared with the white and coloured population groups. Other factors relating to lifestyle and behaviour that differ between the population groups are also likely to influence the age component in SCC.

  20. Creating an anthropomorphic digital MR phantom--an extensible tool for comparing and evaluating quantitative imaging algorithms.

    Science.gov (United States)

    Bosca, Ryan J; Jackson, Edward F

    2016-01-21

    Assessing and mitigating the various sources of bias and variance associated with image quantification algorithms is essential to the use of such algorithms in clinical research and practice. Assessment is usually accomplished with grid-based digital reference objects (DRO) or, more recently, digital anthropomorphic phantoms based on normal human anatomy. Publicly available digital anthropomorphic phantoms can provide a basis for generating realistic model-based DROs that incorporate the heterogeneity commonly found in pathology. Using a publicly available vascular input function (VIF) and digital anthropomorphic phantom of a normal human brain, a methodology was developed to generate a DRO based on the general kinetic model (GKM) that represented realistic and heterogeneously enhancing pathology. GKM parameters were estimated from a deidentified clinical dynamic contrast-enhanced (DCE) MRI exam. This clinical imaging volume was co-registered with a discrete tissue model, and model parameters estimated from clinical images were used to synthesize a DCE-MRI exam that consisted of normal brain tissues and a heterogeneously enhancing brain tumor. An example application of spatial smoothing was used to illustrate potential applications in assessing quantitative imaging algorithms. A voxel-wise Bland-Altman analysis demonstrated negligible differences between the parameters estimated with and without spatial smoothing (using a small radius Gaussian kernel). In this work, we reported an extensible methodology for generating model-based anthropomorphic DROs containing normal and pathological tissue that can be used to assess quantitative imaging algorithms.

  1. Dose conversion coefficients for electron exposure of the human eye lens: calculations including a whole body phantom.

    Science.gov (United States)

    Behrens, R

    2013-07-01

    In this work, conversion coefficients from electron fluence to absorbed dose to the eye lens were calculated using Monte Carlo simulations based on a detailed stylised eye model and a very simple but whole body phantom. These data supersede and complement data published earlier based on the simulation of only a single stylised eye. The new data differ from the old ones by not more than 3, 4, 7 and 16 % for angles of radiation incidence of α=0°, 15°, 30° and 45°, respectively, due to the inclusion of the whole body phantom. The data presented in the present work also complement those of a recent report of the International Commission on Radiological Protection (ICRP) (ICRP Publication 116), where conversion coefficients from electron fluence to absorbed dose to the lens of the eye are shown for solely 0°, 180° and isotropic radiation incidence (but for a much broader range of energies). In this article, values are provided for angles of incidence of 0° up to 180° in steps of 15° and for rotational geometry; no systematic deviation was observed from the values given in ICRP Publication 116 for 0° (based on the application of a bare eye) and 180° (based on the application of a voxel whole body phantom). Data are given for monoenergetic electrons from 0.1 up to 10 MeV and for a broad parallel beam geometry in vacuum.

  2. Laws of Large Numbers for the Occupation Time of an Age-Dependent Critical Binary Branching System

    OpenAIRE

    López-Mimbela, José Alfredo; Salas, Antonio Murillo

    2009-01-01

    The occupation time of an age-dependent branching particle system in $\\Rd$ is considered, where the initial population is a Poisson random field and the particles are subject to symmetric $\\alpha$-stable migration, critical binary branching and random lifetimes. Two regimes of lifetime distributions are considered: lifetimes with finite mean and lifetimes belonging to the normal domain of attraction of a $\\gamma$-stable law, $\\gamma\\in(0,1)$. It is shown that in dimensions $d>\\alpha\\gamma$ fo...

  3. Phenotypic and genetic characterization of a novel phenotype in pigs characterized by juvenile hairlessness and age dependent emphysema

    DEFF Research Database (Denmark)

    Bruun, Camilla S.; Jørgensen, Claus B.; Bay, Lene

    2008-01-01

    Background: A pig phenotype characterized by juvenile hairlessness, thin skin and age dependent lung emphysema has been discovered in a Danish pig herd. The trait shows autosomal co-dominant inheritance with all three genotypes distinguishable. Since the phenotype shows resemblance to the integrin...... of musculi arrectores pili, and at puberty or later localized areas of emphysema are seen in the lungs. Comparative mapping predicted that the porcine ITGB6 and ITGAV orthologs map to SSC15. In an experimentall family (n=113), showing segregation of the trait, the candidate region was confirmed by linkage...

  4. Age-dependent decline in learning and memory performances of WAG/Rij rat model of absence epilepsy

    OpenAIRE

    Karson Ayşe; Utkan Tijen; Balcı Fuat; Arıcıoğlu Feyza; Ateş Nurbay

    2012-01-01

    RESEARCH Open Access Age-dependent decline in learning and memory performances of WAG/Rij rat model of absence epilepsy Ayşe Karson1*, Tijen Utkan2, Fuat Balcı3, Feyza Arıcıoğlu4 and Nurbay Ateş1 Abstract Recent clinical studies revealed emotional and cognitive impairments associated with absence epilepsy. Preclinical research with genetic models of absence epilepsy however have primarily focused on dysfunctional emotional processes and paid relatively less attention t...

  5. Phantom breast sensations are frequent after mastectomy

    DEFF Research Database (Denmark)

    Hansen, Dorthe Marie Helbo; Kehlet, Henrik; Gærtner, Rune

    2011-01-01

    Phantom breast sensation (PBS) following mastectomy has been recognized for many years. PBS is a feeling that the removed breast is still there. The reported prevalence and risk factors have not been established in large well-defined patient series. The purpose of this study was to examine...

  6. A precise CT phantom alignment procedure.

    Science.gov (United States)

    Schneiders, N J; Bushong, S C

    1980-01-01

    Two of the AAPM CT performance phantom inserts require precise alignment. We present a method for aligning an insert which makes use of the partial volume effect. We demonstrate that the procedure is sensitive to tilts of less than one degree and, using the slice thickness insert, allows reproducible positioning.

  7. Note on the Schwarzschild-phantom wormhole

    CERN Document Server

    Lukmanova, Regina; Izmailov, Ramil; Yanbekov, Almir; Karimov, Ramis; Potapov, Alexander A

    2016-01-01

    Recently, it has been shown by Lobo, Parsaei and Riazi (LPR) that phantom energy with $\\omega =p_{r}/\\rho <-1$ could support phantom wormholes. Several classes of such solutions have been derived by them. While the inner spacetime is represented by asymptotically flat phantom wormhole that have repulsive gravity, it is most likely to be unstable to perturbations. Hence, we consider a situation, where a phantom wormhole is somehow trapped inside a Schwarzschild sphere across a thin shell. Applying the method developed by Garcia, Lobo and Visser (GLV), we shall exemplify that the shell can possess zones of stability depending on certain constraints. It turns out that zones corresponding to "force" constraint are more restrictive than those from the "mass" constraint. We shall also enumerate the interior energy content by using the gravitational energy integral proposed by Lynden-Bell, Katz and Bi% \\v{c}\\'ak. It turns out that, even though the interior mass is positive, the integral implies repulsive energy. ...

  8. A comparison of three Deformable Image Registration Algorithms in 4DCT using conventional contour based methods and voxel-by-voxel comparison methods.

    Directory of Open Access Journals (Sweden)

    Mirek eFatyga

    2015-02-01

    Full Text Available Background: Commonly used methods of assessing the accuracy of Deformable Image Registration (DIR rely on image segmentation or landmark selection. These methods are very labor intensive and thus limited to relatively small number of image pairs. The direct voxel-by-voxel comparison can be automated to examine fluctuations in DIR quality on a long series of image pairs.Methods: A voxel-by-voxel comparison of three DIR algorithms applied to lung patients is presented. Registrations are compared by comparing volume histograms formed both with individual DIR maps and with a voxel-by-voxel subtraction of the two maps. When two DIR maps agree one concludes that both maps are interchangeable in treatment planning applications, though one cannot conclude that either one agrees with the ground truth. If two DIR maps significantly disagree one concludes that at least one of the maps deviates from the ground truth. We use the method to compare three DIR algorithms applied to peak inhale-peak exhale registrations of 4DFBCT data obtained from thirteen patients. Results: All three algorithms appear to be nearly equivalent when compared using DICE similarity coefficients. A comparison based on Jacobian Volume Histograms shows that all three algorithms measure changes in total volume of the lungs with reasonable accuracy, but show large differences in the variance of Jacobian distribution on all contoured structures. Analysis of voxel-by-voxel subtraction of DIR maps shows that the three algorithms differ to a degree which is sufficient to create a potential for dosimetric discrepancy during dose accumulation.Conclusions: DIR algorithms can perform well in some clinical applications, while potentially fail in others. These algorithms are best treated as potentially useful approximations of tissue deformation that need to be separately validated for every intended clinical application.

  9. Connecting horizon pixels and interior voxels of a black hole

    Energy Technology Data Exchange (ETDEWEB)

    Nicolini, Piero, E-mail: nicolini@fias.uni-frankfurt.de [Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Institut für Theoretische Physik, J.W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Singleton, Douglas, E-mail: dougs@csufresno.edu [Department of Physics, California State University, Fresno, CA 93740-8031 (United States); Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, Distrito Federal, 04510 (Mexico)

    2014-11-10

    In this paper we discuss to what extent one can infer details of the interior structure of a black hole based on its horizon. Recalling that black hole thermal properties are connected to the non-classical nature of gravity, we circumvent the restrictions of the no-hair theorem by postulating that the black hole interior is singularity free due to violations of the usual energy conditions. Further these conditions allow one to establish a one-to-one, holographic projection between Planckian areal “bits” on the horizon and “voxels”, representing the gravitational degrees of freedom in the black hole interior. We illustrate the repercussions of this idea by discussing an example of the black hole interior consisting of a de Sitter core postulated to arise from the local graviton quantum vacuum energy. It is shown that the black hole entropy can emerge as the statistical entropy of a gas of voxels.

  10. Nanoscale voxel spectroscopy by simultaneous EELS and EDS tomography.

    Science.gov (United States)

    Haberfehlner, Georg; Orthacker, Angelina; Albu, Mihaela; Li, Jiehua; Kothleitner, Gerald

    2014-11-01

    Extending the capabilities of electron tomography with advanced imaging techniques and novel data processing methods, can augment the information content in three-dimensional (3D) reconstructions from projections taken in the transmission electron microscope (TEM). In this work we present the application of simultaneous electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS) to scanning TEM tomography. Various tools, including refined tilt alignment procedures, multivariate statistical analysis and total-variation minimization enable the 3D reconstruction of analytical tomograms, providing 3D analytical metrics of materials science samples at the nanometer scale. This includes volumetric elemental maps, and reconstructions of EDS, low-loss and core-loss EELS spectra as four-dimensional spectrum volumes containing 3D local voxel spectra. From these spectra, compositional, 3D localized elemental analysis becomes possible opening the pathway to 3D nanoscale elemental quantification.

  11. Voxel datacubes for 3D visualization in Blender

    CERN Document Server

    Gárate, Matías

    2016-01-01

    The growth of computational astrophysics and complexity of multidimensional datasets evidences the need for new versatile visualization tools for both analysis and presentation of the data. In this work we show how to use the open source software Blender as a 3D visualization tool to study and visualize numerical simulation results, focusing on astrophysical hydrodynamic experiments. With a datacube as input, the software can generate a volume rendering of the 3D data, show the evolution of a simulation in time, and do a fly-around camera animation to highlight the points of interest. We explain the process to import simulation outputs into Blender using the Voxel Data format, and how to set up a visualization scene in the software interface. This method allows scientists to perform a complementary visual analysis of their data, and display their results in an appealing way, both for outreach and science presentations.

  12. 3D change detection in staggered voxels model for robotic sensing and navigation

    Science.gov (United States)

    Liu, Ruixu; Hampshire, Brandon; Asari, Vijayan K.

    2016-05-01

    3D scene change detection is a challenging problem in robotic sensing and navigation. There are several unpredictable aspects in performing scene change detection. A change detection method which can support various applications in varying environmental conditions is proposed. Point cloud models are acquired from a RGB-D sensor, which provides the required color and depth information. Change detection is performed on robot view point cloud model. A bilateral filter smooths the surface and fills the holes as well as keeps the edge details on depth image. Registration of the point cloud model is implemented by using Random Sample Consensus (RANSAC) algorithm. It uses surface normal as the previous stage for the ground and wall estimate. After preprocessing the data, we create a point voxel model which defines voxel as surface or free space. Then we create a color model which defines each voxel that has a color by the mean of all points' color value in this voxel. The preliminary change detection is detected by XOR subtract on the point voxel model. Next, the eight neighbors for this center voxel are defined. If they are neither all `changed' voxels nor all `no changed' voxels, a histogram of location and hue channel color is estimated. The experimental evaluations performed to evaluate the capability of our algorithm show promising results for novel change detection that indicate all the changing objects with very limited false alarm rate.

  13. Probing the mysterious underpinnings of multi-voxel fMRI analyses.

    Science.gov (United States)

    Op de Beeck, Hans P

    2010-04-01

    Various arguments have been proposed for or against sub-voxel sensitivity or hyperacuity in functional magnetic resonance imaging (fMRI) at standard resolution. Sub-voxel sensitivity might exist, but nevertheless the performance of multi-voxel fMRI analyses is very likely to be dominated by a larger-scale organization, even if this organization is very weak. Up to now, most arguments are indirect in nature: they do not in themselves proof or contradict sub-voxel sensitivity, but they are suggestive, seem consistent or not with sub-voxel sensitivity, or show that the principle might or might not work. Here the previously proposed smoothing argument against hyperacuity is extended with simulations that include more realistic signal, noise, and analysis properties than any of the simulations presented before. These simulations confirm the relevance of the smoothing approach to find out the scale of the functional maps that underlie the outcome of multi-voxel analyses, at least in relative terms (differences in the scale of different maps). However, image smoothing, like most other arguments in the literature, is an indirect argument, and at the end of the day such arguments are not sufficient to decide the issue on whether and how much sub-voxel maps contribute. A few suggestions are made about the type of evidence that is needed to help us understand the as yet mysterious underpinnings of multi-voxel fMRI analyses.

  14. Computational strategies for iterative solutions of large fem applications employing voxel data

    NARCIS (Netherlands)

    R. van Rietbergen (Bert); H.H. Weinans (Harrie); R. Huiskes (Rik); B.J.W. Polman (Ben)

    1996-01-01

    textabstractFE-models for structural solid mechanics analyses can be readily generated from computer images via a 'voxel convesion' method, whereby voxels in a two- or three-dimesional computer image are directly translated to elements in a FE-model. The fact that all elements thus generated are the

  15. In vivo NAD assay reveals the intracellular NAD contents and redox state in healthy human brain and their age dependences.

    Science.gov (United States)

    Zhu, Xiao-Hong; Lu, Ming; Lee, Byeong-Yeul; Ugurbil, Kamil; Chen, Wei

    2015-03-03

    NAD is an essential metabolite that exists in NAD(+) or NADH form in all living cells. Despite its critical roles in regulating mitochondrial energy production through the NAD(+)/NADH redox state and modulating cellular signaling processes through the activity of the NAD(+)-dependent enzymes, the method for quantifying intracellular NAD contents and redox state is limited to a few in vitro or ex vivo assays, which are not suitable for studying a living brain or organ. Here, we present a magnetic resonance (MR) -based in vivo NAD assay that uses the high-field MR scanner and is capable of noninvasively assessing NAD(+) and NADH contents and the NAD(+)/NADH redox state in intact human brain. The results of this study provide the first insight, to our knowledge, into the cellular NAD concentrations and redox state in the brains of healthy volunteers. Furthermore, an age-dependent increase of intracellular NADH and age-dependent reductions in NAD(+), total NAD contents, and NAD(+)/NADH redox potential of the healthy human brain were revealed in this study. The overall findings not only provide direct evidence of declined mitochondrial functions and altered NAD homeostasis that accompany the normal aging process but also, elucidate the merits and potentials of this new NAD assay for noninvasively studying the intracellular NAD metabolism and redox state in normal and diseased human brain or other organs in situ.

  16. Study on the consistency of the voxel of two photon polymerization with inclined beam

    Science.gov (United States)

    Cheng, Kai; Zhou, Xiaoqin; Zheng, Xu; Lin, Jieqiong

    2016-12-01

    In the process of two photon polymerization, the focused beam should be perpendicular to the materials to be processed. But actually it is hard to control, because of the errors of the optical system and the three-dimensional motion platform. So, the inconsistencies of voxels in size and angle due to the errors mentioned above will seriously impact the surface quality of the products. In this paper, the size, angle and location of the titled voxels formed by inclined beam are simulated according to matrix optics and polymerization theory. According to the simulation results, a method for angle errors compensation with the aid of scanning galvanometer is proposed. Although the angle of the voxels can be controlled by scanning galvanometer, but the deflection angles of the scanning galvanometer have a certain range, it should be lower than 3°, or the deformation of the voxels will be serious. Therefore the consistency of the voxel in both size and angle will be ensured.

  17. Rapid three-dimensional quantification of voxel-wise collagen fiber orientation.

    Science.gov (United States)

    Liu, Zhiyi; Quinn, Kyle P; Speroni, Lucia; Arendt, Lisa; Kuperwasser, Charlotte; Sonnenschein, Carlos; Soto, Ana M; Georgakoudi, Irene

    2015-07-01

    Defining fiber orientation at each voxel within a 3D biomedical image stack is potentially useful for a variety of applications, including cancer, wound healing and tissue regeneration. Current methods are typically computationally intensive or inaccurate. Herein, we present a 3D weighted orientation vector summation algorithm, which is a generalization of a previously reported 2D vector summation technique aimed at quantifying collagen fiber orientations simultaneously at each voxel of an image stack. As a result, voxel-wise fiber orientation information with 4° to 5° accuracy can be determined, and the computational time required to analyze a typical stack with the size of 512x512x100 voxels is less than 5 min. Thus, this technique enables the practical extraction of voxel-specific orientation data for characterizing structural anisotropy in 3D specimens. As examples, we use this approach to characterize the fiber organization in an excised mouse mammary gland and a 3D breast tissue model.

  18. Strain- and age-dependent hippocampal neuron sodium currents correlate with epilepsy severity in Dravet syndrome mice.

    Science.gov (United States)

    Mistry, Akshitkumar M; Thompson, Christopher H; Miller, Alison R; Vanoye, Carlos G; George, Alfred L; Kearney, Jennifer A

    2014-05-01

    Heterozygous loss-of-function SCN1A mutations cause Dravet syndrome, an epileptic encephalopathy of infancy that exhibits variable clinical severity. We utilized a heterozygous Scn1a knockout (Scn1a(+/-)) mouse model of Dravet syndrome to investigate the basis for phenotype variability. These animals exhibit strain-dependent seizure severity and survival. Scn1a(+/-) mice on strain 129S6/SvEvTac (129.Scn1a(+/-)) have no overt phenotype and normal survival compared with Scn1a(+/-) mice bred to C57BL/6J (F1.Scn1a(+/-)) that have severe epilepsy and premature lethality. We tested the hypothesis that strain differences in sodium current (INa) density in hippocampal neurons contribute to these divergent phenotypes. Whole-cell voltage-clamp recording was performed on acutely-dissociated hippocampal neurons from postnatal days 21-24 (P21-24) 129.Scn1a(+/-) or F1.Scn1a(+/-) mice and wild-type littermates. INa density was lower in GABAergic interneurons from F1.Scn1a(+/-) mice compared to wild-type littermates, while on the 129 strain there was no difference in GABAergic interneuron INa density between 129.Scn1a(+/-) mice and wild-type littermate controls. By contrast, INa density was elevated in pyramidal neurons from both 129.Scn1a(+/-) and F1.Scn1a(+/-) mice, and was correlated with more frequent spontaneous action potential firing in these neurons, as well as more sustained firing in F1.Scn1a(+/-) neurons. We also observed age-dependent differences in pyramidal neuron INa density between wild-type and Scn1a(+/-) animals. We conclude that preserved INa density in GABAergic interneurons contributes to the milder phenotype of 129.Scn1a(+/-) mice. Furthermore, elevated INa density in excitatory pyramidal neurons at P21-24 correlates with age-dependent onset of lethality in F1.Scn1a(+/-) mice. Our findings illustrate differences in hippocampal neurons that may underlie strain- and age-dependent phenotype severity in a Dravet syndrome mouse model, and emphasize a contribution

  19. Photoacoustic microscopy of bilirubin in tissue phantoms

    Science.gov (United States)

    Zhou, Yong; Zhang, Chi; Yao, Da-Kang; Wang, Lihong V.

    2012-12-01

    Determining both bilirubin's concentration and its spatial distribution are important in disease diagnosis. Here, for the first time, we applied quantitative multiwavelength photoacoustic microscopy (PAM) to detect bilirubin concentration and distribution simultaneously. By measuring tissue-mimicking phantoms with different bilirubin concentrations, we showed that the root-mean-square error of prediction has reached 0.52 and 0.83 mg/dL for pure bilirubin and for blood-mixed bilirubin detection (with 100% oxygen saturation), respectively. We further demonstrated the capability of the PAM system to image bilirubin distribution both with and without blood. Finally, by underlaying bilirubin phantoms with mouse skins, we showed that bilirubin can be imaged with consistent accuracy down to >400 μm in depth. Our results show that PAM has potential for noninvasive bilirubin monitoring in vivo, as well as for further clinical applications.

  20. Phantom cosmology and Boltzmann brains problem

    CERN Document Server

    Astashenok, Artyom V; Yurov, Valerian V

    2013-01-01

    We consider the well-known Boltzmann brains problem in frames of simple phantom energy models with little rip, big rip and big freeze singularity. It is showed that these models (i) satisfy to observational data and (ii) may be free from Boltzmann brains problem. The human observers in phantom models can exist only in during for a certain period $t

  1. Cosmological perturbations on the phantom brane

    Science.gov (United States)

    Bag, Satadru; Viznyuk, Alexander; Shtanov, Yuri; Sahni, Varun

    2016-07-01

    We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, weff Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials Φ and Ψ evolve differently on the brane than in ΛCDM, for which Φ = Ψ. On the brane, by contrast, the ratio Φ/Ψ exceeds unity during the late matter-dominated epoch (z lesssim 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large-scale structure.

  2. Fabrication of Two Flow Phantoms for Doppler Ultrasound Imaging.

    Science.gov (United States)

    Zhou, Xiaowei; Kenwright, David A; Wang, Shiying; Hossack, John A; Hoskins, Peter R

    2017-01-01

    Flow phantoms are widely used in studies associated with Doppler ultrasound measurements, acting as an effective experimental validation system in cardiovascular-related research and in new algorithm/instrumentation development. The development of materials that match the acoustic and mechanical properties of the vascular system is of great interest while designing flow phantoms. Although recipes that meet the flow phantom standard defined by the International Electrotechnical Commission 61685 are already available in the literature, the standard procedure for material preparations and phantom fabrications has not been well established. In this paper, two types of flow phantoms, with and without blood vessel mimic, are described in detail in terms of the material preparation and phantom fabrication. The phantom materials chosen for the two phantoms are from published phantom studies, and their physical properties have been investigated previously. Both the flow phantoms have been scanned by ultrasound scanners and images from different modes are presented. These phantoms may be used in the validation and characterization of Doppler ultrasound measurements in blood vessels with a diameter above 1 mm.

  3. Semen collection using phantom in dromedary camel.

    Science.gov (United States)

    Ziapour, S; Niasari-Naslaji, A; Mirtavousi, M; Keshavarz, M; Kalantari, A; Adel, H

    2014-12-10

    Semen collection is relatively long, unsafe, and tedious procedure in dromedary camel. The innovation of safe, hygienic, and simple approach to collect semen could make great progress in development of AI program in this species. This study investigated two methods of semen collection using phantom and artificial vagina in dromedary camel. Semen was collected using phantom (n = 4 bulls; 26 collections) and artificial vagina (n = 6 bulls; 11 collections) and diluted with INRA96 at the ratio of 1:10. The duration of semen collection, semen parameters, and morphometric features of sperm were evaluated. For specimen collected through phantom and AV, the respected duration of semen collection (411.2 ± 48.19 vs 326 ± 37.05 sec), volume (6.6 ± 0.87 vs 6 ± 1.57 ml), osmolarity (328 ± 1.6 vs 319.4 ± 3.21 mOsm/kg H2O), pH (7.7 ± 0.06 vs 7.9 ± 0.16) of semen, concentration (161.4 ± 44.05 × 10(6)/mL vs 160.2 ± 58.42 × 10(6)/mL), total motility (84.1 ± 1.89 vs 78.3 ± 3.97%), progressive forward motility (45.5 ± 3.69 vs 44.3 ± 6.41%), live percentage (72.2 ± 3.11 vs 76 ± 2.53%), and plasma membrane integrity (61.5 ± 2.49 vs 58.9 ± 4.19%) of sperm were similar (P > 0.05). The number of specimens contaminated with visible particles was greater using AV (72.7%) compared to phantom (0%; P dromedary camel.

  4. Phantoms for Radiation Measurements of Mobile Phones

    DEFF Research Database (Denmark)

    Pedersen, Gert Frølund

    2001-01-01

    Measurements of radiation efficiency for a handheld phone equipped with a patch and a helical antenna operated near the human user have been performed. Both measurements include a simple head plus hand phantom and live persons are considered. The position of the hand on the phone is found...... to be the main reason for the large variation in radiation efficiency among persons. The tilt angle of the phone and the distance between the head and phone only play a minor role...

  5. Age-Dependent Effects of Methylphenidate on the Human Dopaminergic System in Young vs Adult Patients With Attention-Deficit/Hyperactivity Disorder: A Randomized Clincal Trial

    NARCIS (Netherlands)

    Schrantee, A.; Tamminga, H.G.H.; Bouziane, C.; Bottelier, M.A.; Bron, E.E.; Mutsaerts, H.J.M.M.; Zwinderman, A.H.; Groote, I.R.; Rombouts, S.A.R.B.; Lindauer, R.J.L.; Klein, S.; Niessen, W.J.; Opmeer, B.C.; Boer, F.; Lucassen, P.J.; Andersen, S.L.; Geurts, H.M.; Reneman, L.

    2016-01-01

    Importance: Although numerous children receive methylphenidate hydrochloride for the treatment of attention-deficit/hyperactivity disorder (ADHD), little is known about age-dependent and possibly lasting effects of methylphenidate on the human dopaminergic system. Objectives: To determine whether th

  6. Age-dependent susceptibilities of Bulinus truncatus snails to an aqueous extract of Pulicaria crispa (Forssk.) Oliv. (Asteraceae) leaves.

    Science.gov (United States)

    Ali, Elnour A; Bushara, Hamid O; Ali, Faisal S; Hussein, Mansour F

    2009-05-01

    This study was carried out to investigate the potential use of the herb Pulicaria crispa in the biological control of different developmental stages of Bulinus truncatus, a major snail intermediate host of urinary schistosomiasis. Age-dependent susceptibilities of mature adult snails, immature snails, juveniles, and one-day old egg masses to aqueous extracts of Pulicaria crispa leaves collected from Khartoum (Sudan) and Riyadh (Saudi Arabia) was determined and compared. The results show the juvenile snails are the most susceptible, followed in descending order by one-day old egg masses, immature snails, and mature adult snails. The P. crispa sample collected from Riyadh was significantly more potent against B. truncatus than that collected from Khartoum, as indicated by the least (LC50) and (LC90) values for all B. truncatus ages.

  7. [ROLE OF NEUTRAL SPHINGOMYELINASE IN AGE-DEPENDENT MUSCLE INSULIN RESISTANCE DEVELOPMENT AND ITS IMPROVEMENT WITH N-ACETYLCYSTEINE].

    Science.gov (United States)

    Babenko, N A; Timofiĭchuk, O A; Belyĭ, A N

    2015-01-01

    In the present study, we evaluated the role of ceramide in age-dependent and etoposide-induced insulin resistance. A significant increase in the level of ceramide and decrease of gluthatione (GSH) content and tissue sensitivity to insulin has been observed in 24-month-old rats as compared with 3-month-old animals. Etoposide imitates ageing-like changes in muscle tissue of young rats. N-acetylcysteine as well as specific neutral sphingomyelinase (nSMase) inhibitor--GW4869, decreases ceramide content and increases GSH level, and enhances the insulin-induced [3H-D-glucose uptake in the "aged" tissue. These data indicate that nSMase play important role in the age- and drug-induced ceramide-dependent insuline resistance.

  8. The structure of optimal time- and age-dependent harvesting in the Lotka-McKendrik population model.

    Science.gov (United States)

    Hritonenko, Natali; Yatsenko, Yuri

    2007-07-01

    The paper analyzes optimal harvesting of age-structured populations described by the Lotka-McKendrik model. It is shown that the optimal time- and age-dependent harvesting control involves only one age at natural conditions. This result leads to a new optimization problem with the time-dependent harvesting age as an unknown control. The integral Lotka model is employed to explicitly describe the time-varying age of harvesting. It is proven that in the case of the exponential discounting and infinite horizon the optimal strategy is a stationary solution with a constant harvesting age. A numeric example on optimal forest management illustrates the theoretical findings. Discussion and interpretation of the results are provided.

  9. Estimating true age-dependence in survival when only adults can be observed: an example with Black-legged Kittiwakes

    Directory of Open Access Journals (Sweden)

    Frederiksen, M.

    2004-06-01

    Full Text Available In long-lived birds, pre-breeders are often difficult or impossible to observe, and even though a proportion of marked adults may be of known age, the estimation of age-specific survival is complicated by the absence of observations during the first years of life. New developments in MARK now allow use of an updated individual covariate. We used this powerful approach to model age-dependence in survival of Black-legged Kittiwakes (Rissa tridactyla at a North Sea colony. Although only 69 marked breeders were of known age, there was strong evidence for a quadratic relationship between true age and survival. We believe that this simple but powerful approach could be implemented for many species and could provide improved estimates of how survival changes with age, a central theme in life history theory.

  10. An approach to calculating childhood body burdens of dibenzodioxins and dibenzofurans which accounts for age-dependent biological half lives

    Energy Technology Data Exchange (ETDEWEB)

    Paustenbach, D. [ChemRisk, San Francisco, CA (United States); Leung, H.W. [Leung, H.W. Private Consultant, Danbury, CT (United States); Scott, P. [ChemRisk, Pittsburgh, PA (United States); Kerger, B. [HSRI, Tallahassee, FL (United States)

    2004-09-15

    The purpose of this study is to apply an age-dependent half life model to examine the range of child (ages 0-7) body burdens that correspond to selected exposure scenarios involving background dietary and environmental doses of dioxins. The scenarios examined include breast-fed and nonbreast- fed infants feeding for 6 months, other dioxin uptake from foods through age 7, and exposures to urban residential soils at 1 ppb TCDD toxic equivalents (TEQ). These body burden estimates in children are then compared to the adult body burden estimates corresponding to the range of tolerable daily intakes (1 to 4 pg TEQ/kg-day) proposed by some U.S. and international regulatory/advisory groups.

  11. Age-dependent potassium iodide effect on the thyroid irradiation by 131I and 133I in the nuclear emergency.

    Science.gov (United States)

    Jang, M; Kim, H K; Choi, C W; Kang, C S

    2008-01-01

    The initial near-field exposure is primarily through inhalation in a nuclear emergency and the dominant contribution to the effective inhalation dose comes from radioiodine. Thyroid blockade by oral potassium iodide (KI) is efficient and practical for public in the nuclear emergency. Age-dependent radioprotective effect of KI on the thyroid irradiation by (131)I and (133)I has been derived using the simplified compartment model of iodine metabolism and WinSAAM program. Administration of KI within 2 h after (131)I and (133)I intake can block thyroid uptake significantly, yielding protective effect of 78.9% and 74.3%, respectively, for (131)I and (133)I for adults. The mean absorbed doses decrease with age, while protective effects of KI are similar for all age groups.

  12. Automatic Synthesis of Anthropomorphic Pulmonary CT Phantoms

    Science.gov (United States)

    Jimenez-Carretero, Daniel; San Jose Estepar, Raul; Diaz Cacio, Mario; Ledesma-Carbayo, Maria J.

    2016-01-01

    The great density and structural complexity of pulmonary vessels and airways impose limitations on the generation of accurate reference standards, which are critical in training and in the validation of image processing methods for features such as pulmonary vessel segmentation or artery–vein (AV) separations. The design of synthetic computed tomography (CT) images of the lung could overcome these difficulties by providing a database of pseudorealistic cases in a constrained and controlled scenario where each part of the image is differentiated unequivocally. This work demonstrates a complete framework to generate computational anthropomorphic CT phantoms of the human lung automatically. Starting from biological and image-based knowledge about the topology and relationships between structures, the system is able to generate synthetic pulmonary arteries, veins, and airways using iterative growth methods that can be merged into a final simulated lung with realistic features. A dataset of 24 labeled anthropomorphic pulmonary CT phantoms were synthesized with the proposed system. Visual examination and quantitative measurements of intensity distributions, dispersion of structures and relationships between pulmonary air and blood flow systems show good correspondence between real and synthetic lungs (p > 0.05 with low Cohen’s d effect size and AUC values), supporting the potentiality of the tool and the usefulness of the generated phantoms in the biomedical image processing field. PMID:26731653

  13. Automatic Synthesis of Anthropomorphic Pulmonary CT Phantoms.

    Directory of Open Access Journals (Sweden)

    Daniel Jimenez-Carretero

    Full Text Available The great density and structural complexity of pulmonary vessels and airways impose limitations on the generation of accurate reference standards, which are critical in training and in the validation of image processing methods for features such as pulmonary vessel segmentation or artery-vein (AV separations. The design of synthetic computed tomography (CT images of the lung could overcome these difficulties by providing a database of pseudorealistic cases in a constrained and controlled scenario where each part of the image is differentiated unequivocally. This work demonstrates a complete framework to generate computational anthropomorphic CT phantoms of the human lung automatically. Starting from biological and image-based knowledge about the topology and relationships between structures, the system is able to generate synthetic pulmonary arteries, veins, and airways using iterative growth methods that can be merged into a final simulated lung with realistic features. A dataset of 24 labeled anthropomorphic pulmonary CT phantoms were synthesized with the proposed system. Visual examination and quantitative measurements of intensity distributions, dispersion of structures and relationships between pulmonary air and blood flow systems show good correspondence between real and synthetic lungs (p > 0.05 with low Cohen's d effect size and AUC values, supporting the potentiality of the tool and the usefulness of the generated phantoms in the biomedical image processing field.

  14. Inverse U-shaped curve for age dependency of torsional eye movement responses to galvanic vestibular stimulation.

    Science.gov (United States)

    Jahn, Klaus; Naessl, Andrea; Schneider, Erich; Strupp, Michael; Brandt, Thomas; Dieterich, Marianne

    2003-07-01

    To investigate age dependent changes we analysed torsional eye movement responses to binaural and monaural galvanic vestibular stimulation (GVS) in 57 healthy subjects (20-69 years old). GVS (1-3 mA) induced torsional eye movements consisting of static torsion toward the anode (amplitude 1-6 degrees ) and superimposed torsional nystagmus (slow phase velocity 0.5-3 degrees /s, quick phase amplitude 0.5-2 degrees, nystagmus frequency 0.75-1.5 s-1). Static ocular torsion and torsional nystagmus increased from the third to the sixth decade and decreased in older subjects, e.g. slow phase velocity increased from 1.5 degrees /s (20-29 years) to 2.9 degrees /s (50-59 years) and decreased to 2.5 degrees /s for the seventh decade (60-69 years). Thus, an inverse U-shaped curve was found for the dependence of torsional eye movement responses on age. All structures relevant for vestibular function degenerate with age, but at varying times. Since hair cell loss precedes those seen in the vestibular nerve and Scarpa's ganglion, the decrease in hair cell counts could be compensated for by increased sensitivity of afferent nerve fibres or central mechanisms. Increased sensitivity could thus maintain normal function despite reduced peripheral input. As GVS acts at the vestibular nerve (thereby bypassing the hair cells), electrical stimulation should be more efficient in subjects with the beginning of hair cell degeneration, as seen in our data up to the sixth decade. The degeneration of nerve fibres, ganglion cells and central neurons becomes evident at older ages. Thus, the compensatory increase in sensitivity breaks down and GVS-induced eye movements decline-a finding that is reflected by the inverse U-shaped curve for age dependency presented in this study.

  15. Simulated Microgravity Exerts an Age-Dependent Effect on the Differentiation of Cardiovascular Progenitors Isolated from the Human Heart.

    Directory of Open Access Journals (Sweden)

    Tania I Fuentes

    Full Text Available Microgravity has a profound effect on cardiovascular function, however, little is known about the impact of microgravity on progenitors that reside within the heart. We investigated the effect of simulated microgravity exposure on progenitors isolated from the neonatal and adult human heart by quantifying changes in functional parameters, gene expression and protein levels after 6-7 days of 2D clinorotation. Utilization of neonatal and adult cardiovascular progenitors in ground-based studies has provided novel insight into how microgravity may affect cells differently depending on age. Simulated microgravity exposure did not impact AKT or ERK phosphorylation levels and did not influence cell migration, but elevated transcripts for paracrine factors were identified in neonatal and adult cardiovascular progenitors. Age-dependent responses surfaced when comparing the impact of microgravity on differentiation. Endothelial cell tube formation was unchanged or increased in progenitors from adults whereas neonatal cardiovascular progenitors showed a decline in tube formation (p<0.05. Von Willebrand Factor, an endothelial differentiation marker, and MLC2v and Troponin T, markers for cardiomyogenic differentiation, were elevated in expression in adult progenitors after simulated microgravity. DNA repair genes and telomerase reverse transcriptase which are highly expressed in early stem cells were increased in expression in neonatal but not adult cardiac progenitors after growth under simulated microgravity conditions. Neonatal cardiac progenitors demonstrated higher levels of MESP1, OCT4, and brachyury, markers for early stem cells. MicroRNA profiling was used to further investigate the impact of simulated microgravity on cardiovascular progenitors. Fifteen microRNAs were significantly altered in expression, including microRNAs-99a and 100 (which play a critical role in cell dedifferentiation. These microRNAs were unchanged in adult cardiac progenitors

  16. Early restriction of alphavirus replication and dissemination contributes to age-dependent attenuation of systemic hyperinflammatory disease.

    Science.gov (United States)

    Ryman, Kate D; Gardner, Christina L; Meier, Kathryn C; Biron, Christine A; Johnston, Robert E; Klimstra, William B

    2007-02-01

    Severity of alphavirus infection in humans tends to be strongly age-dependent and several studies using laboratory-adapted Sindbis virus (SB) AR339 strains have indicated that SB-induced disease in mice is similarly contingent upon host developmental status. In the current studies, the consensus wild-type SB, TR339, and in vivo imaging technology have been utilized to examine virus replication and disease manifestations in mice infected subcutaneously at 5 days of age (5D) vs 11D. Initial virulence studies with TR339 indicated that this age range is coincident with rapid transition from fatal to non-fatal outcome. Fatal infection of 5D mice is characterized by high-titre serum viraemia, extensive virus replication in skin, fibroblast connective tissue, muscle and brain, and hyperinflammatory cytokine induction. In contrast, 11D-infected mice experience more limited virus replication and tissue damage and develop mild, immune-mediated pathologies including encephalitis. These results further establish the linkage between hyperinflammatory cytokine induction and fatal outcome of infection. In vivo imaging using luciferase-expressing viruses and non-propagative replicons revealed that host development results in a restriction of virus replication within individual infected cells that is manifested as a delay in reduction of virus replication in the younger mice. Thus, an important contributing factor in age-dependent resistance to alphavirus infection is restriction of replication within first infected cells in peripheral tissues, which may augment other developmentally regulated attenuating effects, such as increasing neuronal resistance to virus infection and apoptotic death.

  17. Age-dependent decline in mouse lung regeneration with loss of lung fibroblast clonogenicity and increased myofibroblastic differentiation.

    Directory of Open Access Journals (Sweden)

    Julia A Paxson

    Full Text Available While aging leads to a reduction in the capacity for regeneration after pneumonectomy (PNX in most mammals, this biological phenomenon has not been characterized over the lifetime of mice. We measured the age-specific (3, 9, 24 month effects of PNX on physiology, morphometry, cell proliferation and apoptosis, global gene expression, and lung fibroblast phenotype and clonogenicity in female C57BL6 mice. The data show that only 3 month old mice were fully capable of restoring lung volumes by day 7 and total alveolar surface area by 21 days. By 9 months, the rate of regeneration was slower (with incomplete regeneration by 21 days, and by 24 months there was no regrowth 21 days post-PNX. The early decline in regeneration rate was not associated with changes in alveolar epithelial cell type II (AECII proliferation or apoptosis rate. However, significant apoptosis and lack of cell proliferation was evident after PNX in both total cells and AECII cells in 24 mo mice. Analysis of gene expression at several time points (1, 3 and 7 days post-PNX in 9 versus 3 month mice was consistent with a myofibroblast signature (increased Tnc, Lox1, Col3A1, Eln and Tnfrsf12a and more alpha smooth muscle actin (αSMA positive myofibroblasts were present after PNX in 9 month than 3 month mice. Isolated lung fibroblasts showed a significant age-dependent loss of clonogenicity. Moreover, lung fibroblasts isolated from 9 and 17 month mice exhibited higher αSMA, Col3A1, Fn1 and S100A expression, and lower expression of the survival gene Mdk consistent with terminal differentiation. These data show that concomitant loss of clonogenicity and progressive myofibroblastic differentiation contributes to the age-dependent decline in the rate of lung regeneration.

  18. An Age-Dependent Physiologically-Based Pharmacokinetic/Pharmacodynamic Model for the Organophosphorus Insecticide Chlorpyrifos in the Preweanling Rat

    Energy Technology Data Exchange (ETDEWEB)

    Timchalk, Chuck; Kousba, Ahmed A.; Poet, Torka S.

    2007-08-01

    Juvenile rats are more susceptible than adults to the acute toxicity of organophosphorus insecticides like chlorpyrifos (CPF). Age- and dose-dependent differences in metabolism may be responsible. Of importance is CYP450 activation and detoxification of CPF to chlorpyrifos-oxon (CPF-oxon) and trichloropyridinol (TCP), as well as B-esterase (cholinesterase; ChE) and A-esterase (PON-1) detoxification of CPF-oxon to TCP. In the current study, a modified physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model incorporating age-dependent changes in CYP450, PON-1, and tissue ChE levels for rats was developed. In this model, age was used as a dependent function to estimate body weight which was then used to allometrically scale both metabolism and tissue ChE levels. Model simulations suggest that preweanling rats are particularly sensitive to CPF toxicity, with levels of CPF-oxon in blood and brain disproportionately increasing, relative to the response in adult rats. This age-dependent non-linear increase in CPF-oxon concentration may potentially result from the depletion of non-target B-esterases, and a lower PON-1 metabolic capacity in younger animals. These results indicate that the PBPK/PD model behaves consistently with the general understanding of CPF toxicity, pharmacokinetics and tissue ChE inhibition in neonatal and adult rats. Hence, this model represents an important starting point for developing a computational model to assess the neurotoxic potential of environmentally relevant organophosphate exposures in infants and children.

  19. A free database of radionuclide voxel S values for the dosimetry of nonuniform activity distributions

    Science.gov (United States)

    Lanconelli, N.; Pacilio, M.; Lo Meo, S.; Botta, F.; Di Dia, A.; Torres Aroche, L. A.; Coca Pérez, M. A.; Cremonesi, M.

    2012-01-01

    The increasing availability of SPECT/CT devices with advanced technology offers the opportunity for the accurate assessment of the radiation dose to the biological target volume during radionuclide therapy. Voxel dosimetry can be performed employing direct Monte Carlo radiation transport simulations, based on both morphological and functional images of the patient. On the other hand, for voxel dosimetry calculations the voxel S value method can be considered an easier approach than patient-specific Monte Carlo simulations, ensuring a good dosimetric accuracy at least for anatomic regions which are characterized by uniform density tissue. However, this approach has been limited because of the lack of tabulated S values for different voxel dimensions and radionuclides. The aim of this work is to provide a free dataset of values which can be used for voxel dosimetry in targeted radionuclide studies. Seven different radionuclides (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, 188Re), and 13 different voxel sizes (2.21, 2.33, 2.4, 3, 3.59, 3.9, 4, 4.42, 4.8, 5, 6, 6.8 and 9.28 mm) are considered. Voxel S values are calculated performing simulations of monochromatic photon and electron sources in two different homogeneous tissues (soft tissue and bone) with DOSXYZnrc code, and weighting the contributions on the basis of the radionuclide emission spectra. The outcomes are validated by comparison with Monte Carlo simulations obtained with other codes (PENELOPE and MCNP4c) performing direct simulation of the radionuclide emission spectra. The differences among the different Monte Carlo codes are of the order of a few per cent when considering the source voxel and the bremsstrahlung tail, whereas the highest differences are observed at a distance close to the maximum continuous slowing down approximation range of electrons. These discrepancies would negligibly affect dosimetric assessments. The dataset of voxel S values can be freely downloaded from the website www.medphys.it.

  20. A free database of radionuclide voxel S values for the dosimetry of nonuniform activity distributions.

    Science.gov (United States)

    Lanconelli, N; Pacilio, M; Lo Meo, S; Botta, F; Di Dia, A; Aroche, A Torres; Pérez, M A Coca; Cremonesi, M

    2012-01-21

    The increasing availability of SPECT/CT devices with advanced technology offers the opportunity for the accurate assessment of the radiation dose to the biological target volume during radionuclide therapy. Voxel dosimetry can be performed employing direct Monte Carlo radiation transport simulations, based on both morphological and functional images of the patient. On the other hand, for voxel dosimetry calculations the voxel S value method can be considered an easier approach than patient-specific Monte Carlo simulations, ensuring a good dosimetric accuracy at least for anatomic regions which are characterized by uniform density tissue. However, this approach has been limited because of the lack of tabulated S values for different voxel dimensions and radionuclides. The aim of this work is to provide a free dataset of values which can be used for voxel dosimetry in targeted radionuclide studies. Seven different radionuclides (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, 188Re), and 13 different voxel sizes (2.21, 2.33, 2.4, 3, 3.59, 3.9, 4, 4.42, 4.8, 5, 6, 6.8 and 9.28 mm) are considered. Voxel S values are calculated performing simulations of monochromatic photon and electron sources in two different homogeneous tissues (soft tissue and bone) with DOSXYZnrc code, and weighting the contributions on the basis of the radionuclide emission spectra. The outcomes are validated by comparison with Monte Carlo simulations obtained with other codes (PENELOPE and MCNP4c) performing direct simulation of the radionuclide emission spectra. The differences among the different Monte Carlo codes are of the order of a few per cent when considering the source voxel and the bremsstrahlung tail, whereas the highest differences are observed at a distance close to the maximum continuous slowing down approximation range of electrons. These discrepancies would negligibly affect dosimetric assessments. The dataset of voxel S values can be freely downloaded from the website www.medphys.it.

  1. What do differences between multi-voxel and univariate analysis mean? How subject-, voxel-, and trial-level variance impact fMRI analysis.

    Science.gov (United States)

    Davis, Tyler; LaRocque, Karen F; Mumford, Jeanette A; Norman, Kenneth A; Wagner, Anthony D; Poldrack, Russell A

    2014-08-15

    Multi-voxel pattern analysis (MVPA) has led to major changes in how fMRI data are analyzed and interpreted. Many studies now report both MVPA results and results from standard univariate voxel-wise analysis, often with the goal of drawing different conclusions from each. Because MVPA results can be sensitive to latent multidimensional representations and processes whereas univariate voxel-wise analysis cannot, one conclusion that is often drawn when MVPA and univariate results differ is that the activation patterns underlying MVPA results contain a multidimensional code. In the current study, we conducted simulations to formally test this assumption. Our findings reveal that MVPA tests are sensitive to the magnitude of voxel-level variability in the effect of a condition within subjects, even when the same linear relationship is coded in all voxels. We also find that MVPA is insensitive to subject-level variability in mean activation across an ROI, which is the primary variance component of interest in many standard univariate tests. Together, these results illustrate that differences between MVPA and univariate tests do not afford conclusions about the nature or dimensionality of the neural code. Instead, targeted tests of the informational content and/or dimensionality of activation patterns are critical for drawing strong conclusions about the representational codes that are indicated by significant MVPA results.

  2. Empirical comparison of maximal voxel and non-isotropic adjusted cluster extent results in a voxel-based morphometry study of comorbid learning disability with schizophrenia.

    Science.gov (United States)

    Moorhead, T William J; Job, Dominic E; Spencer, Michael D; Whalley, Heather C; Johnstone, Eve C; Lawrie, Stephen M

    2005-11-15

    We present an empirical comparison of cluster extent and maximal voxel results in a voxel-based morphometry (VBM) study of brain structure. The cluster extents are adjusted for underlying deviation from uniform smoothness. We implement this comparison on a four-group cohort that has previously shown evidence of a neuro-developmental component in schizophrenia (Moorhead, T.W.J., Job, D.E., Whalley, H.C., Sanderson, T.L., Johnstone, E.C. and Lawrie, S.M. 2004. Voxel-based morphometry of comorbid schizophrenia and learning disability: analyses in normalized and native spaces using parametric and nonparametric statistical methods. NeuroImage 22: 188-202.). We find that adjusted cluster extent results provide information on the nature of deficits that occur in the schizophrenia affected groups, and these important structural differences are not all shown in maximal voxel results. The maximal voxel and cluster extent results are corrected for multiple comparisons using Random Fields (RF) methods. In order to apply the cluster extent measures, we propose a post-hoc method for determining the primary threshold in the analysis. Unadjusted cluster extent results are reported, for these, no allowance is made for non-isotropic smoothness, and comparison with the adjusted extent results shows that the unadjusted results can be either conservative or anti-conservative depending upon the underlying tissue distributions.

  3. Voxel-based morphometry in autopsy proven PSP and CBD.

    Science.gov (United States)

    Josephs, Keith A; Whitwell, Jennifer L; Dickson, Dennis W; Boeve, Bradley F; Knopman, David S; Petersen, Ronald C; Parisi, Joseph E; Jack, Clifford R

    2008-02-01

    The aim of this study was to compare the patterns of grey and white matter atrophy on MRI in autopsy confirmed progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), and to determine whether the patterns vary depending on the clinical syndrome. Voxel-based morphometry was used to compare patterns of atrophy in 13 PSP and 11 CBD subjects and 24 controls. PSP and CBD subjects were also subdivided into those with a dominant dementia or extrapyramidal syndrome. PSP subjects showed brainstem atrophy with involvement of the cortex and underlying white matter. Frontoparietal grey and subcortical grey matter atrophy occurred in CBD. When subdivided, PSP subjects with an extrapyramidal syndrome had more brainstem atrophy and less cortical atrophy than CBD subjects with an extrapyramidal syndrome. PSP subjects with a dementia syndrome had more subcortical white matter atrophy than CBD subjects with a dementia syndrome. These results show regional differences between PSP and CBD that are useful in predicting the underlying pathology, and help to shed light on the in vivo distribution of regional atrophy in PSP and CBD.

  4. A study of partial volume effect on SPECT imaging using myocardial phantom. With HCM (ASH) model myocardial phantom

    Energy Technology Data Exchange (ETDEWEB)

    Onoguchi, Masahisa [Kanazawa Univ. (Japan). School of Medicine

    1997-05-01

    In order to evaluate simultaneously both myocardial perfusion and regional wall motion using ECG-gated myocardial SPECT imaging, correction for the partial volume effect (PVE) should be performed. For the quantitative analysis of myocardial SPECT imaging in patients with hypertrophic cardiomyopathy (HCM), we formed a new phantom simulating HCM with various septal wall thicknesses and estimated PVE using the recovery coefficient (RC). The value of RC in all phantoms increased with increasing thickness of the septal wall reaching a plateau at 25 mm for the cylindrical phantom and 25 mm for the Ep-phantom. Compared with the RC value, the PMMA-phantom had little influence on PVE. Therefore, our results suggested that the count in the septal wall could be underestimated if PVE was corrected by the value obtained for the cylindrical phantom. In conclusion, our new phantom simulating HCM was useful in assessing PVE in the hypertrophic septal wall. (author)

  5. TU-F-17A-03: A 4D Lung Phantom for Coupled Registration/Segmentation Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Markel, D; El Naqa, I [McGill University, Montreal, QC (Canada); Levesque, I [Montreal University Health Centre, Montreal, Quebec (Canada)

    2014-06-15

    Purpose: Coupling the processes of segmentation and registration (regmentation) is a recent development that allows improved efficiency and accuracy for both steps and may improve the clinical feasibility of online adaptive radiotherapy. Presented is a multimodality animal tissue model designed specifically to provide a ground truth to simultaneously evaluate segmentation and registration errors during respiratory motion. Methods: Tumor surrogates were constructed from vacuum sealed hydrated natural sea sponges with catheters used for the injection of PET radiotracer. These contained two compartments allowing for two concentrations of radiotracer mimicking both tumor and background signals. The lungs were inflated to different volumes using an air pump and flow valve and scanned using PET/CT and MRI. Anatomical landmarks were used to evaluate the registration accuracy using an automated bifurcation tracking pipeline for reproducibility. The bifurcation tracking accuracy was assessed using virtual deformations of 2.6 cm, 5.2 cm and 7.8 cm of a CT scan of a corresponding human thorax. Bifurcations were detected in the deformed dataset and compared to known deformation coordinates for 76 points. Results: The bifurcation tracking accuracy was found to have a mean error of −0.94, 0.79 and −0.57 voxels in the left-right, anterior-posterior and inferior-superior axes using a 1×1×5 mm3 resolution after the CT volume was deformed 7.8 cm. The tumor surrogates provided a segmentation ground truth after being registered to the phantom image. Conclusion: A swine lung model in conjunction with vacuum sealed sponges and a bifurcation tracking algorithm is presented that is MRI, PET and CT compatible and anatomically and kinetically realistic. Corresponding software for tracking anatomical landmarks within the phantom shows sub-voxel accuracy. Vacuum sealed sponges provide realistic tumor surrogate with a known boundary. A ground truth with minimal uncertainty is thus

  6. Outstanding Trend of Voxel-Man%可视人真实可视化的突出进展Voxel-Man(2)

    Institute of Scientific and Technical Information of China (English)

    秦笃烈

    2004-01-01

    @@ 3 Voxel-Man的应用 Voxel-Man既是一套3D数字解剖学的生动而杰出的应用程序,也是一个开发其他应用程序的平台.K.H.Hohne教授领导的研究人员不断在利用这个平台开发各种有价值、有新意的医学教育和临床应用.

  7. Distinct Cortical Pathways for Music and Speech Revealed by Hypothesis-Free Voxel Decomposition.

    Science.gov (United States)

    Norman-Haignere, Sam; Kanwisher, Nancy G; McDermott, Josh H

    2015-12-16

    The organization of human auditory cortex remains unresolved, due in part to the small stimulus sets common to fMRI studies and the overlap of neural populations within voxels. To address these challenges, we measured fMRI responses to 165 natural sounds and inferred canonical response profiles ("components") whose weighted combinations explained voxel responses throughout auditory cortex. This analysis revealed six components, each with interpretable response characteristics despite being unconstrained by prior functional hypotheses. Four components embodied selectivity for particular acoustic features (frequency, spectrotemporal modulation, pitch). Two others exhibited pronounced selectivity for music and speech, respectively, and were not explainable by standard acoustic features. Anatomically, music and speech selectivity concentrated in distinct regions of non-primary auditory cortex. However, music selectivity was weak in raw voxel responses, and its detection required a decomposition method. Voxel decomposition identifies primary dimensions of response variation across natural sounds, revealing distinct cortical pathways for music and speech.

  8. Age-dependent pharmacokinetic and pharmacodynamic response in preweanling rats following oral exposure to the organophosphorus insecticide chlorpyrifos

    Energy Technology Data Exchange (ETDEWEB)

    Timchalk, Chuck; Poet, Torka S.; Kousba, Ahmed A.

    2006-03-01

    Juvenile rats are more susceptible than adults to the acute toxicity of organophosphorus insecticides like chlorpyrifos (CPF). Age- and dose-dependent differences in metabolism may be responsible. Of importance is CYP450 activation and detoxification of CPF to CPF-oxon and 3,5,6-trichloro-2-pyridinol (TCP), as well as B-esterase (cholinesterase; ChE) and A-esterase (PON-1) detoxification of CPF-oxon to TCP. The pharmacokinetics of CPF, TCP, and the extent of blood (plasma/RBC), and brain ChE inhibition in rats were determined on postnatal days (PND) -5, -12, and -17 following oral gavage administration of 1 and 10 mg CPF/kg of body weight. For all neonatal ages the blood TCP exceeded the CPF concentration, and within each age group there was no evidence of non-linear kinetics over the dose range evaluated. Younger animals demonstrated a greater sensitivity to ChE inhibition as evident by the dose- and age-dependent inhibition of plasma, RBC, and brain ChE. Of particular importance was the observation that even in rats as young as PND-5, the CYP450 metabolic capacity was adequate to metabolize CPF to both TCP and CPF-oxon based on the detection of TCP in blood and extensive ChE inhibition (biomarker of CPF-oxon) at all ages. In addition, the increase in the blood TCP concentration ({approx}3-fold) in PND-17 rats relative to the response in the younger animals, and the higher blood concentrations of CPF in neonatal rats (1.7 to 7.5-fold) relative to adults was consistent with an increase in CYP450 metabolic capacity with age. This is the first reported study that evaluated both the pharmacokinetics of the parent pesticide, the major metabolite and the extent of ChE inhibition dynamics in the same animals as a function of neonatal age. The results suggest that in the neonatal rat, CPF was rapidly absorbed and metabolized, and the extent of metabolism was age-dependent.

  9. Postprocessing of Voxel-Based Topologies for Additive Manufacturing Using the Computational Geometry Algorithms Library (CGAL)

    Science.gov (United States)

    2015-06-01

    surfaces such as Catmull-Clark or Doo-Sabin. 2.1 Topology Optimization Topology optimization applied to structural problems using a voxel/pixel geometry...O. Topology optimization: Theory, methods and appli - cations. Springer; 2003. (Engineering Online Library). 2. Brackett D, Ashcroft I, Hague R. 22nd...ARL-MR-0892• JUNE 2015 US Army Research Laboratory Postprocessing of Voxel-Based Topologies forAdditive Manufacturing Using the Compu-tational

  10. Recipes to make organic phantoms for diffusive optical spectroscopy.

    Science.gov (United States)

    Quarto, Giovanna; Pifferi, Antonio; Bargigia, Ilaria; Farina, Andrea; Cubeddu, Rinaldo; Taroni, Paola

    2013-04-10

    Three recipes are presented to make tissue constituent-equivalent phantoms of water and lipids. Different approaches to prepare the emulsion are proposed. Nature phantoms are made using no emulsifying agent, but just a professional disperser; instead Agar and Triton phantoms are made using agar or Triton X-100, respectively, as agents to emulsify water and lipids. Different water-to-lipid ratios ranging from 30% to 70% by mass were tested. A broadband time-resolved diffuse optical spectroscopy system was used to characterize the phantoms in terms of optical properties and composition. For some water/lipid ratios the emulsion fails or the phantom has limited lifetime, but in most cases the recipes provide phantoms with a high degree of homogeneity [coefficient of variation (CV) of 4.6% and 1.5% for the absorption and reduced scattering coefficient, respectively] and good reproducibility (CV of 8.3% and 12.4% for absorption and reduced scattering coefficient, respectively).

  11. Characterization of a phantom setup for breast conserving cancer surgery

    Science.gov (United States)

    Chadwell, Jacob T.; Conley, Rebekah H.; Collins, Jarrod A.; Meszoely, Ingrid M.; Miga, Michael I.

    2016-03-01

    The purpose of this work is to develop an anatomically and mechanically representative breast phantom for the validation of breast conserving surgical therapies, specifically, in this case, image guided surgeries. Using three patients scheduled for lumpectomy and four healthy volunteers in mock surgical presentations, the magnitude, direction, and location of breast deformations was analyzed. A phantom setup was then designed to approximate such deformations in a mock surgical environment. Specifically, commercially available and custom-built polyvinyl alcohol (PVA) phantoms were used to mimic breast tissue during surgery. A custom designed deformation apparatus was then created to reproduce deformations seen in typical clinical setups of the pre- and intra-operative breast geometry. Quantitative analysis of the human subjects yielded a positive correlation between breast volume and amount of breast deformation. Phantom results reflected similar behavior with the custom-built PVA phantom outperforming the commercial phantom.

  12. Polarized light propagation through tissue and tissue phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, V; Walsh, J T JR; Maitland, D J

    2000-02-08

    We show that standard tissue phantoms can be used to mimic the intensity and polarization properties of tissue. Polarized light propagation through biologic tissue is typically studied using tissue phantoms consisting of dilute aqueous suspensions of microspheres. The dilute phantoms can empirically match tissue polarization and intensity properties. One discrepancy between the dilute phantoms and tissue exist: common tissue phantoms, such as dilute Intralipid and dilute 1-{micro}m-diameter polystyrene microsphere suspensions, depolarize linearly polarized light more quickly than circularly polarized light. In dense tissue, however, where scatterers are often located in close proximity to one another, circularly polarized light is depolarized similar to or more quickly than linearly polarized light. We also demonstrate that polarized light propagates differently in dilute versus densely packed microsphere suspensions, which may account for the differences seen between polarized light propagation in common dilute tissue phantoms versus dense biologic tissue.

  13. Development of thyroid anthropomorphic phantoms for use in nuclear medicine

    Science.gov (United States)

    Cerqueira, R. A. D.; Maia, A. F.

    2014-02-01

    The objective of this study was to develop thyroid anthropomorphic phantoms to be used in control tests of medical images in scintillation cameras. The main difference among the phantoms was the neck shape: in the first, called OSCT, it was geometrically shaped, while in the second, called OSAP, it was anthropomorphically shaped. In both phantoms, thyroid gland prototypes, which were made of acrylic and anthropomorphically shaped, were constructed to allow the simulation of a healthy thyroid and of thyroids with hyperthyroidism and hypothyroidism. Images of these thyroid anthropomorphic phantoms were obtained using iodine 131 with an activity of 8.695 MBq. The iodine 131 was chosen because it is widely used in studies of thyroid scintigraphy. The images obtained proved the effectiveness of the phantoms to simulate normal or abnormal thyroids function. These phantoms can be used in medical imaging quality control programs and, also in the training of professionals involved in the analysis of images in nuclear medicine centers.

  14. Dosimeter placement in the Rando phantom

    Energy Technology Data Exchange (ETDEWEB)

    Archer, B.R.; Glaze, S.; North, L.B.; Bushong, S.C.

    1977-07-01

    Each section of the Alderson Rando phantom contains a tissue-equivalent plastic coating layer approximately 2 mm thick, applied to both faces. This compensates for material removed in the sawing process. Conventional use of thermoluminescent dosimeters positions them totally or partially within the coating layer. Analysis shows that, in the lung region, dosimeters placed in this layer received a dose averaging 39% lower than those placed at midsection. Where bony structures interfere, some dosimeters in the coating layer received an 18% higher dose than those at midsection. Therefore, positioning dosimeters at the center of a section is recommended.

  15. Phantom Energy with Variable G and A

    Institute of Scientific and Technical Information of China (English)

    Arbab Ⅰ. Arbab

    2008-01-01

    @@ We investigate a cosmological model of a phantom energy with a variable cosmological constant (A) depending on the energy density (p) as A α ρ-α, α = const and a variable gravitational constant G. The model requires α -1 and α 0 and p decrease with cosmic expansion. For ordinary energy (or dark energy), i.e.ω > -1, we have -1 0 so that G > 0 increases with time and ρ decreases with time. Cosmic acceleration with dust particles is granted, provided -2/3 0.

  16. Viscous dark energy and phantom evolution

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Mauricio [Departamento de Fisica, Facultad de Ciencias, Universidad del Bio-Bio, Avenida Collao 1202, Casilla 5-C, Concepcion (Chile)]. E-mail: mcataldo@ubiobio.cl; Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile)]. E-mail: ncruz@lauca.usach.cl; Lepe, Samuel [Instituto de Fisica, Facultad de Ciencias Basicas y Matematicas, Pontificia Universidad Catolica de Valparaiso, Avenida Brasil 2950, Valparaiso (Chile)]. E-mail: slepe@ucv.cl

    2005-07-14

    In order to study if the bulk viscosity may induce a big rip singularity on the flat FRW cosmologies, we investigate dissipative processes in the universe within the framework of the standard Eckart theory of relativistic irreversible thermodynamics, and in the full causal Israel-Stewart-Hiscock theory. We have found cosmological solutions which exhibit, under certain constraints, a big rip singularity. We show that the negative pressure generated by the bulk viscosity cannot avoid that the dark energy of the universe to be phantom energy.

  17. Getting started with PhantomJS

    CERN Document Server

    Beltran, Aries

    2013-01-01

    The book will follow aA standard tutorial approach, and will beas a complete guide detailing the major aspects of PhantomJS with particular focus on Website website Testingtesting.This book is written forIf you are a JavaScript developers who are is interested in developing applications that interact with various web services, and doing that using a headless browser, then this book is ideal for you. This book iswill also be good for you if you are planning to create a headless browser testing for your web application. Basic understanding of JavaScript is assumed.

  18. A novel, optimized approach of voxel division for water vapor tomography

    Science.gov (United States)

    Yao, Yibin; Zhao, Qingzhi

    2017-02-01

    Water vapor information with highly spatial and temporal resolution can be acquired using Global Navigation Satellite System (GNSS) water vapor tomography technique. Usually, the targeted tomographic area is discretized into a number of voxels and the water vapor distribution can be reconstructed using a large number of GNSS signals which penetrate the entire tomographic area. Due to the influence of geographic distribution of receivers and geometric location of satellite constellation, many voxels located at the bottom and the side of research area are not crossed by signals, which would undermine the quality of tomographic result. To alleviate this problem, a novel, optimized approach of voxel division is here proposed which increases the number of voxels crossed by signals. On the vertical axis, a 3D water vapor profile is utilized, which is derived from radiosonde data for many years, to identify the maximum height of tomography space. On the horizontal axis, the total number of voxel crossed by signal is enhanced, based on the concept of non-uniform symmetrical division of horizontal voxels. In this study, tomographic experiments are implemented using GPS data from Hong Kong Satellite Positioning Reference Station Network, and tomographic result is compared with water vapor derived from radiosonde and European Center for Medium-Range Weather Forecasting (ECMWF). The result shows that the Integrated Water Vapour (IWV), RMS, and error distribution of the proposed approach are better than that of traditional method.

  19. Informational connectivity: identifying synchronized discriminability of multi-voxel patterns across the brain.

    Science.gov (United States)

    Coutanche, Marc N; Thompson-Schill, Sharon L

    2013-01-01

    The fluctuations in a brain region's activation levels over a functional magnetic resonance imaging (fMRI) time-course are used in functional connectivity (FC) to identify networks with synchronous responses. It is increasingly recognized that multi-voxel activity patterns contain information that cannot be extracted from univariate activation levels. Here we present a novel analysis method that quantifies regions' synchrony in multi-voxel activity pattern discriminability, rather than univariate activation, across a timeseries. We introduce a measure of multi-voxel pattern discriminability at each time-point, which is then used to identify regions that share synchronous time-courses of condition-specific multi-voxel information. This method has the sensitivity and access to distributed information that multi-voxel pattern analysis enjoys, allowing it to be applied to data from conditions not separable by univariate responses. We demonstrate this by analyzing data collected while people viewed four different types of man-made objects (typically not separable by univariate analyses) using both FC and informational connectivity (IC) methods. IC reveals networks of object-processing regions that are not detectable using FC. The IC results support prior findings and hypotheses about object processing. This new method allows investigators to ask questions that are not addressable through typical FC, just as multi-voxel pattern analysis (MVPA) has added new research avenues to those addressable with the general linear model (GLM).

  20. Voxel classification methodology for rapid Monte Carlo simulation of light propagation in complex media

    Institute of Scientific and Technical Information of China (English)

    Nunu Ren; Heng Zhao; Shouping Zhu; Xiaochao Qu; Hongliang Liu; Zhenhua Hu; Jimin Liang; Jie Tian

    2011-01-01

    @@ Monte Carlo (MC) method is a statistical method for simulating photon propagation in media in the optical molecular imaging field.However, obtaining an accurate result using the method is quite time-consuming,especially because the boundary of the media is complex.A voxel classification method is proposed to reduce the computation cost.All the voxels generated by dividing the media are classified into three types (outside, boundary, and inside) according to the position of the voxel.The classified information is used to determine the relative position of the photon and the intersection between photon path and media boundary in the MC method.The influencing factor8 and effectiveness of the proposed method are analyzed and validated by simulation experiments.%Monte Carlo (MC) method is a statistical method for simulating photon propagation in media in the optical molecular imaging field. However, obtaining an accurate result using the method is quite time-consuming,especially because the boundary of the media is complex. A voxel classification method is proposed to reduce the computation cost. All the voxels generated by dividing the media are classified into three types (outside, boundary, and inside) according to the position of the voxel. The classified information is used to determine the relative position of the photon and the intersection between photon path and media boundary in the MC method. The influencing factors and effectiveness of the proposed method are analyzed and validated by simulation experiments.

  1. Prevalent Hallucinations during Medical Internships: Phantom Vibration and Ringing Syndromes

    OpenAIRE

    Yu-Hsuan Lin; Sheng-Hsuan Lin; Peng Li; Wei-Lieh Huang; Ching-Yen Chen

    2013-01-01

    BACKGROUND: Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. METHODS: A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years) was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying sympto...

  2. Studies on Phantom Vibration and Ringing Syndrome among Postgraduate Students

    OpenAIRE

    Atul Kumar Goyal

    2015-01-01

    Phantom vibrations and ringing of mobile phones are prevalent hallucinations in the general population. They might be considered as a normal brain mechanism. The aim of this study was to establish the prevalence of Phantom vibrations and ringing syndrome among students and to assess factors associated it. The survey of 300 postgraduate students belonging to different field of specialization was conducted at Kurukshetra University. 74% of students were found to have both Phantom vibrations and...

  3. Creating 3D gelatin phantoms for experimental evaluation in biomedicine

    Directory of Open Access Journals (Sweden)

    Stein Nils

    2015-09-01

    Full Text Available We describe and evaluate a setup to create gelatin phantoms by robotic 3D printing. Key aspects are the large workspace, reproducibility and resolution of the created phantoms. Given its soft tissue nature, the gelatin is kept fluid during inside the system and we present parameters for additive printing of homogeneous, solid objects. The results indicate that 3D printing of gelatin can be an alternative for quickly creating larger soft tissue phantoms without the need for casting a mold.

  4. AfAP2-1, An Age-Dependent Gene of Aechmea fasciata, Responds to Exogenous Ethylene Treatment

    Directory of Open Access Journals (Sweden)

    Ming Lei

    2016-02-01

    Full Text Available The Bromeliaceae family is one of the most morphologically diverse families with a pantropical distribution. To schedule an appropriate flowering time for bromeliads, ethylene is commonly used to initiate flower development in adult plants. However, the mechanism by which ethylene induces flowering in adult bromeliads remains unknown. Here, we identified an APETALA2 (AP2-like gene, AfAP2-1, in Aechmea fasciata. AfAP2-1 contains two AP2 domains and is a nuclear-localized protein. It functions as a transcriptional activator, and the activation domain is located in the C-terminal region. The expression level of AfAP2-1 is higher in juvenile plants than in adult plants, and the AfAP2-1 transcript level was rapidly and transiently reduced in plants treated with exogenous ethylene. Overexpression of AfAP2-1 in Arabidopsis thaliana results in an extremely delayed flowering phenotype. These results suggested that AfAP2-1 responds to ethylene and is a putative age-dependent flowering regulator in A. fasciata.

  5. FDA-approved drugs that protect mammalian neurons from glucose toxicity slow aging dependent on cbp and protect against proteotoxicity.

    Directory of Open Access Journals (Sweden)

    Alex Lublin

    Full Text Available Screening a library of drugs with known safety profiles in humans yielded 30 drugs that reliably protected mammalian neurons against glucose toxicity. Subsequent screening demonstrated that 6 of these 30 drugs increase lifespan in C. elegans: caffeine, ciclopirox olamine, tannic acid, acetaminophen, bacitracin, and baicalein. Every drug significantly reduced the age-dependent acceleration of mortality rate. These protective effects were blocked by RNAi inhibition of cbp-1 in adults only, which also blocks protective effects of dietary restriction. Only 2 drugs, caffeine and tannic acid, exhibited a similar dependency on DAF-16. Caffeine, tannic acid, and bacitracin also reduced pathology in a transgenic model of proteotoxicity associated with Alzheimer's disease. These results further support a key role for glucose toxicity in driving age-related pathologies and for CBP-1 in protection against age-related pathologies. These results also provide novel lead compounds with known safety profiles in human for treatment of age-related diseases, including Alzheimer's disease and diabetic complications.

  6. Rapamycin activates autophagy in Hutchinson-Gilford progeria syndrome: implications for normal aging and age-dependent neurodegenerative disorders.

    Science.gov (United States)

    Graziotto, John J; Cao, Kan; Collins, Francis S; Krainc, Dimitri

    2012-01-01

    While rapamycin has been in use for years in transplant patients as an antirejection drug, more recently it has shown promise in treating diseases of aging, such as neurodegenerative disorders and atherosclerosis. We recently reported that rapamycin reverses the cellular phenotype of fibroblasts from children with the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS). We found that the causative aberrant protein, progerin, was cleared through autophagic mechanisms when the cells were treated with rapamycin, suggesting a new potential treatment for HGPS. Recent evidence shows that progerin is also present in aged tissues of healthy individuals, suggesting that progerin may contribute to physiological aging. While it is intriguing to speculate that rapamycin may affect normal aging in humans, as it does in lower organisms, it will be important to identify safer analogues of rapamycin for chronic treatments in humans in order to minimize toxicity. In addition to its role in HGPS and normal aging, we discuss the potential of rapamycin for the treatment of age-dependent neurodegenerative diseases.

  7. Apolipoprotein E4 Causes Age-Dependent Disruption of Slow Gamma Oscillations during Hippocampal Sharp-Wave Ripples.

    Science.gov (United States)

    Gillespie, Anna K; Jones, Emily A; Lin, Yuan-Hung; Karlsson, Mattias P; Kay, Kenneth; Yoon, Seo Yeon; Tong, Leslie M; Nova, Philip; Carr, Jessie S; Frank, Loren M; Huang, Yadong

    2016-05-18

    Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD), but the mechanism by which it causes cognitive decline is unclear. In knockin (KI) mice, human apoE4 causes age-dependent learning and memory impairments and degeneration of GABAergic interneurons in the hippocampal dentate gyrus. Here we report two functional apoE4-KI phenotypes involving sharp-wave ripples (SWRs), hippocampal network events critical for memory processes. Aged apoE4-KI mice had fewer SWRs than apoE3-KI mice and significantly reduced slow gamma activity during SWRs. Elimination of apoE4 in GABAergic interneurons, which prevents learning and memory impairments, rescued SWR-associated slow gamma activity but not SWR abundance in aged mice. SWR abundance was reduced similarly in young and aged apoE4-KI mice; however, the full SWR-associated slow gamma deficit emerged only in aged apoE4-KI mice. These results suggest that progressive decline of interneuron-enabled slow gamma activity during SWRs critically contributes to apoE4-mediated learning and memory impairments. VIDEO ABSTRACT.

  8. Contents of chemical elements in stomach during prenatal development: different age-dependent dynamical changes and their significance

    Institute of Scientific and Technical Information of China (English)

    Shao-Fan Hou; Hai-Rong Li; Li-Zhen Wang; De-Zhu Li; Lin-Sheng Yang; Chong-Zheng Li

    2003-01-01

    AIM: To observe dynamic of different chemical elements in stomach tissue during fetal development.METHODS: To determine contents of the 21 chemical elements in each stomach samples from fetus aging four to ten months. The content values were compared to those from adult tissue samples, and the values for each month group were also analyzed for dynamic changes.RESULTS: Three representations were found regarding the relationship between contents of the elements and ages of the fetus, including the positive correlative (K), reversely correlative (Na, Ca, P, Al, Cu, Zn, Fe, Mn, Cr, Sr, Li, Cd, Ba,Se ) and irrelevant groups (Mg, Co, Ni, V, Pb, Ti).CONCLUSION: The chemical elements' contents in stomach tissues were found to change dynamically with the stomach weights. The age-dependent representations for different chemical elements during the prenatal development may be of some significance for assessing development of fetal stomach and some chemical elements. The data may be helpful for the nutritional balance of fetus and mothers during prenatal development and even the perinatal stages.

  9. Age-dependent occurrence of an ascending axon on the omega neuron of the cricket, Teleogryllus oceanicus.

    Science.gov (United States)

    Atkins, G; Pollack, G S

    1986-01-22

    The omega neurons (ON1s) are a mirror-symmetrical pair of identified prothoracic auditory interneurons of crickets which have been previously described as intraganglionic. Using intracellular techniques we stained ON1s of female Teleogryllus oceanicus and found that many ON1s have axons which project anteriorly out of the prothoracic ganglion. The ascending axon arises contralateral to the soma at the most anteriolateral bend of the bow-shaped process of an otherwise "archetypical" ON1 and travels up the neck connective in a ventral position just inside the connective tissue sheath. The occurrence of the ascending axon is age-dependent. Seventy-five percent of ON1s stained in late nymphal stages and in young adults had an ascending axon while only 30% of ON1s in older adults had an ascending axon. Evidence is presented to show that ON1s having ascending axons are developmental variants of the "archetypical" ON1 and do not represent a separate neuron type. The two morphological types of ON1s are not distinguishable on the basis of their responses to sound stimuli having carrier frequencies of 3.5-60 kHz. Although we know that the ascending axon conducts action potentials, its target and terminal morphology are not yet known.

  10. Non-Gaussian statistical properties of virtual breast phantoms

    Science.gov (United States)

    Abbey, Craig K.; Bakic, Predrag R.; Pokrajac, David D.; Maidment, Andrew D. A.; Eckstein, Miguel P.; Boone, John M.

    2014-03-01

    Images derived from a "phantom" are useful for characterizing the performance of imaging systems. In particular, the modulation transfer properties of imaging detectors are traditionally assessed by physical phantoms consisting of an edge. More recently researchers have come to realize that quantifying the effects of object variability can also be accomplished with phantoms in modalities such as breast imaging where anatomical structure may be the principal limitation in performance. This has driven development of virtual phantoms that can be used in simulation environments. In breast imaging, several such phantoms have been proposed. In this work, we analyze non-Gaussian statistical properties of virtual phantoms, and compare them to similar statistics from a database of breast images. The virtual phantoms assessed consist of three classes. The first is known as clustered-blob lumpy backgrounds. The second class is "binarized" textures which typically apply some sort of threshold to a stochastic 3D texture intended to represent the distribution of adipose and glandular tissue in the breast. The third approach comes from efforts at the University of Pennsylvania to directly simulate the 3D anatomy of the breast. We use Laplacian fractional entropy (LFE) as a measure of the non-Gaussian statistical properties of each simulation. Our results show that the simulation approaches differ considerably in LFE with very low scores for the clustered-blob lumpy background to very high values for the UPenn phantom. These results suggest that LFE may have value in developing and tuning virtual phantom simulation procedures.

  11. Galileons, phantom fields, and the fate of the Universe

    Science.gov (United States)

    Shahalam, M.; Pacif, S. K. J.; Myrzakulov, R.

    2016-07-01

    In this paper we study cosmological dynamics of the phantom as well as non-phantom fields with a linear potential in the presence of a Galileon correction (partial _μ φ partial ^μ φ ) Box φ . We show that the Big Crunch singularity is delayed compared to the standard case; the delay crucially depends upon the strength of a Galileon correction. As for the phantom Galileon, ρ _{φ } is shown to grow more slowly compared to the standard phantom delaying the approach of the singularity. In the case, V˜ φ ^n, n>4, Big Rip is also delayed, similar phenomenon is shown to take place for potentials steeper than the exponential.

  12. Theoretical analysis of phantom rotations in BSD-DTI.

    Science.gov (United States)

    Krzyzak, Artur; Borkowski, Karol

    2015-08-01

    A novel method of improving accuracy of diffusion tensor imaging (DTI), called BSD-DTI (B-spatial distribution in DTI), has been recently proposed. Determination of the b matrix components using an anisotropic phantom, and derivation of the spatial distribution are of the essence in this approach. So far, a sufficient uniformity of the diffusion properties across the entire phantom has been assumed. Nevertheless, BSD-DTI is not limited only to highly homogeneous phantoms. This study describes a procedure which allows to use basically any anisotropic phantom of a precisely defined structure.

  13. Breast phantom for mammary tissue characterization by near infrared spectroscopy

    Science.gov (United States)

    Miranda, D. A.; Cristiano, K. L.; Gutiérrez, J. C.

    2013-11-01

    Breast cancer is a disease associated to a high morbidity and mortality in the entire world. In the study of early detection of breast cancer the development of phantom is so important. In this research we fabricate a breast phantom using a ballistic gel with special modifications to simulate a normal and abnormal human breast. Optical properties of woman breast in the near infrared region were modelled with the phantom we developed. The developed phantom was evaluated with near infrared spectroscopy in order to study its relation with breast tissue. A good optical behaviour was achieved with the model fabricated.

  14. [Development of a software for 3D virtual phantom design].

    Science.gov (United States)

    Zou, Lian; Xie, Zhao; Wu, Qi

    2014-02-01

    In this paper, we present a 3D virtual phantom design software, which was developed based on object-oriented programming methodology and dedicated to medical physics research. This software was named Magical Phan tom (MPhantom), which is composed of 3D visual builder module and virtual CT scanner. The users can conveniently construct any complex 3D phantom, and then export the phantom as DICOM 3.0 CT images. MPhantom is a user-friendly and powerful software for 3D phantom configuration, and has passed the real scene's application test. MPhantom will accelerate the Monte Carlo simulation for dose calculation in radiation therapy and X ray imaging reconstruction algorithm research.

  15. Phantom Eye Syndrome: A Review of the Literature

    Directory of Open Access Journals (Sweden)

    Agda M. Andreotti

    2014-01-01

    Full Text Available The purpose of this literature review was to describe the main features of phantom eye syndrome in relation to their possible causes, symptoms, treatments, and influence of eye amputation on quality of life of anophthalmic patients. For this, a bibliographical research was performed in Pubmed database using the following terms: “eye amputation,” “eye trauma,” “phantom eye syndrome,” “phantom pain,” and “quality of life,” associated or not. Thirteen studies were selected, besides some relevant references contained in the selected manuscripts and other studies hallowed in the literature. Thus, 56 articles were included in this review. The phantom eye syndrome is defined as any sensation reported by the patient with anophthalmia, originated anophthalmic cavity. In phantom eye syndrome, at least one of these three symptoms has to be present: phantom vision, phantom pain, and phantom sensations. This syndrome has a direct influence on the quality of life of the patients, and psychological support is recommended before and after the amputation of the eyeball as well as aid in the treatment of the syndrome. Therefore, it is suggested that, for more effective treatment of phantom eye syndrome, drug therapy should be associated with psychological approach.

  16. Examining the Viability of Phantom Dark Energy

    CERN Document Server

    Ludwick, Kevin J

    2015-01-01

    In the standard cosmological framework of the 0th-order FLRW metric and the use of perfect fluids in the stress-energy tensor, dark energy with an equation-of-state parameter $w < -1$ (known as phantom dark energy) implies negative kinetic energy and vacuum instability when modeled as a scalar field. However, the value of best fit from Planck and WMAP9 for present-day $w$ is indeed less than $-1$. We find that it is not as obvious as one might think that phantom dark energy has negative kinetic energy categorically. Staying within the confines of observational constraints and general relativity, for which there is good experimental validation, we consider a few reasonable departures from the standard 0th-order framework in an attempt to see if negative kinetic energy can be avoided in these settings despite an apparent $w<-1$. We consider a more accurate description of the universe through the perturbing of the isotropic and homogeneous FLRW metric and the components of the stress-energy tensor, and we ...

  17. Phantom black holes and critical phenomena

    CERN Document Server

    Azreg-Aïnou, Mustapha; Rodrigues, Manuel E

    2014-01-01

    We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-Dilaton theory. Leaving aside the normal Reissner-Nordstr\\"om black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to ...

  18. Creation of 3D digital anthropomorphic phantoms which model actual patient non-rigid body motion as determined from MRI and position tracking studies of volunteers

    Science.gov (United States)

    Connolly, C. M.; Konik, A.; Dasari, P. K. R.; Segars, P.; Zheng, S.; Johnson, K. L.; Dey, J.; King, M. A.

    2011-03-01

    Patient motion can cause artifacts, which can lead to difficulty in interpretation. The purpose of this study is to create 3D digital anthropomorphic phantoms which model the location of the structures of the chest and upper abdomen of human volunteers undergoing a series of clinically relevant motions. The 3D anatomy is modeled using the XCAT phantom and based on MRI studies. The NURBS surfaces of the XCAT are interactively adapted to fit the MRI studies. A detailed XCAT phantom is first developed from an EKG triggered Navigator acquisition composed of sagittal slices with a 3 x 3 x 3 mm voxel dimension. Rigid body motion states are then acquired at breath-hold as sagittal slices partially covering the thorax, centered on the heart, with 9 mm gaps between them. For non-rigid body motion requiring greater sampling, modified Navigator sequences covering the entire thorax with 3 mm gaps between slices are obtained. The structures of the initial XCAT are then adapted to fit these different motion states. Simultaneous to MRI imaging the positions of multiple reflective markers on stretchy bands about the volunteer's chest and abdomen are optically tracked in 3D via stereo imaging. These phantoms with combined position tracking will be used to investigate both imaging-data-driven and motion-tracking strategies to estimate and correct for patient motion. Our initial application will be to cardiacperfusion SPECT imaging where the XCAT phantoms will be used to create patient activity and attenuation distributions for each volunteer with corresponding motion tracking data from the markers on the body-surface. Monte Carlo methods will then be used to simulate SPECT acquisitions, which will be used to evaluate various motion estimation and correction strategies.

  19. MRI thermometry in phantoms by use of the proton resonance frequency shift method: application to interstitial laser thermotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Olsrud, Johan; Wirestam, Ronnie; Brockstedt, Sara; Persson, Bertil R.R. [Department of Radiation Physics, Lund University Hospital, SE-221 85 Lund (Sweden); Nilsson, Annika M.K. [Department of Physics, Lund Institute of Technology, SE-221 00 Lund (Sweden); Tranberg, Karl-Goeran [Department of Surgery, Lund University Hospital, SE-221 85 Lund (Sweden); Staahlberg, Freddy [Department of Radiation Physics, Lund University Hospital, SE-221 85 Lund (Sweden); Department of Diagnostic Radiology, Lund University Hospital, SE-221 85 Lund (Sweden)

    1998-09-01

    In this work the temperature dependence of the proton resonance frequency was assessed in agarose gel with a high melting temperature (95 deg. C) and in porcine liver in vitro at temperatures relevant to thermotherapy (25-80 deg. C). Furthermore, an optically tissue-like agarose gel phantom was developed and evaluated for use in MRI. The phantom was used to visualize temperature distributions from a diffusing laser fibre by means of the proton resonance frequency shift method. An approximately linear relationship (0.0085 ppm deg. C{sup -1}) between proton resonance frequency shift and temperature change was found for agarose gel, whereas deviations from a linear relationship were observed for porcine liver. The optically tissue-like agarose gel allowed reliable MRI temperature monitoring, and the MR relaxation times (T{sub 1} and T{sub 2}) and the optical properties were found to be independently alterable. Temperature distributions around a diffusing laser fibre, during irradiation and subsequent cooling, were assessed with high spatial resolution (voxel size = 4.3 mm{sup 3}) and with random uncertainties ranging from 0.3 deg. C to 1.4 deg. C (1 SD) with a 40 s scan time. (author)

  20. Calculation of indoor effective dose factors in ORNL phantoms series due to natural radioactivity in building materials.

    Science.gov (United States)

    Krstic, D; Nikezic, D

    2009-10-01

    In this paper the effective dose in the age-dependent ORNL phantoms series, due to naturally occurring radionuclides in building materials, was calculated. The absorbed doses for various organs or human tissues have been calculated. The MCNP-4B computer code was used for this purpose. The effective dose was calculated according to ICRP Publication 74. The obtained values of dose conversion factors for a standard room are: 1.033, 0.752 and 0.0538 nSv h-1 per Bq kg-1 for elements of the U and Th decay series and for the K isotope, respectively. The values of effective dose agreed generally with those found in the literature, although the values estimated here for elements of the U series were higher in some cases.

  1. Variation in voxel value distribution and effect of time between exposures in six CBCT units.

    Science.gov (United States)

    Spin-Neto, R; Gotfredsen, E; Wenzel, A

    2014-01-01

    The aim of this study is to assess the variation in voxel value distribution in volumetric data sets obtained by six cone beam CT (CBCT) units, and the effect of time between exposures. Six CBCT units [Cranex(®) 3D (CRAN; Soredex Oy, Tuusula, Finland), Scanora(®) 3D (SCAN; Soredex Oy), NewTom™ 5G (NEWT; QR Srl, Verona, Italy), Promax(®) Dimax 3 (Planmeca Oy, Helsinki, Finland), i-CAT (Imaging Sciences International, Hatfield, PA) and 3D Accuitomo FPD80 (Morita, Kyoto, Japan)] were tested. Two volumetric data sets of a dry human skull embedded in acrylic were acquired by each CBCT unit in two sessions on separate days. Each session consisted of 20 exposures: 10 acquired with 30 min between exposures and 10 acquired immediately one after the other. CBCT data were exported as digital imaging and communications in medicine (DICOM) files and converted to text files. The text files were re-organized to contain x-, y- and z-position and grey shade for each voxel. The files were merged to contain 1 record per voxel position, including the voxel values from the 20 exposures in a session. For each voxel, subtractions were performed between Data Set 1 and the remaining 19 data sets (1 - 2, 1 - 3, etc) in a session. Means, medians, ranges and standard deviations for grey shade variation in the subtraction data sets were calculated for each unit and session. For all CBCT units, variation in voxel values was observed throughout the 20 exposures. A "fingerprint" for the grey shade variation was observed for CRAN, SCAN and NEWT. For the other units, the variation was (apparently) randomly distributed. Large discrepancies in voxel value distribution are seen in CBCT images. This variation should be considered in studies that assess minute changes in CBCT images.

  2. NbCSPR underlies age-dependent immune responses to bacterial cold shock protein in Nicotiana benthamiana.

    Science.gov (United States)

    Saur, Isabel M L; Kadota, Yasuhiro; Sklenar, Jan; Holton, Nicholas J; Smakowska, Elwira; Belkhadir, Youssef; Zipfel, Cyril; Rathjen, John P

    2016-03-22

    Plants use receptor kinases (RKs) and receptor-like proteins (RLPs) as pattern recognition receptors (PRRs) to sense pathogen-associated molecular patterns (PAMPs) that are typical of whole classes of microbes. After ligand perception, many leucine-rich repeat (LRR)-containing PRRs interact with the LRR-RK BRI1-ASSOCIATED KINASE 1 (BAK1). BAK1 is thus expected to interact with unknown PRRs. Here, we used BAK1 as molecular bait to identify a previously unknown LRR-RLP required for the recognition of the csp22 peptide derived from bacterial cold shock protein. We established a method to identify proteins that interact with BAK1 only after csp22 treatment. BAK1 was expressed transiently in Nicotiana benthamiana and immunopurified after treatment with csp22. BAK1-associated proteins were identified by mass spectrometry. We identified several proteins including known BAK1 interactors and a previously uncharacterized LRR-RLP that we termed RECEPTOR-LIKE PROTEIN REQUIRED FOR CSP22 RESPONSIVENESS (NbCSPR). This RLP associates with BAK1 upon csp22 treatment, and NbCSPR-silenced plants are impaired in csp22-induced defense responses. NbCSPR confers resistance to bacteria in an age-dependent and flagellin-induced manner. As such, it limits bacterial growth and Agrobacterium-mediated transformation of flowering N. benthamiana plants. Transgenic expression of NbCSPR into Arabidopsis thaliana conferred responsiveness to csp22 and antibacterial resistance. Our method may be used to identify LRR-type RKs and RLPs required for PAMP perception/responsiveness, even when the active purified PAMP has not been defined.

  3. Cerebellar cortex development in the weaver condition presents regional and age-dependent abnormalities without differences in Purkinje cells neurogenesis.

    Science.gov (United States)

    Martí, Joaquín; Santa-Cruz, María C; Hervás, José P; Bayer, Shirley A; Villegas, Sandra

    2016-01-01

    Ataxias are neurological disorders associated with the degeneration of Purkinje cells (PCs). Homozygous weaver mice (wv/wv) have been proposed as a model for hereditary cerebellar ataxia because they present motor abnormalities and PC loss. To ascertain the physiopathology of the weaver condition, the development of the cerebellar cortex lobes was examined at postnatal day (P): P8, P20 and P90. Three approaches were used: 1) quantitative determination of several cerebellar features; 2) qualitative evaluation of the developmental changes occurring in the cortical lobes; and 3) autoradiographic analyses of PC generation and placement. Our results revealed a reduction in the size of the wv/wv cerebellum as a whole, confirming previous results. However, as distinguished from these reports, we observed that quantified parameters contribute differently to the abnormal growth of the wv/wv cerebellar lobes. Qualitative analysis showed anomalies in wv/wv cerebellar cytoarchitecture, depending on the age and lobe analyzed. Such abnormalities included the presence of the external granular layer after P20 and, at P90, ectopic cells located in the molecular layer following several placement patterns. Finally, we obtained autoradiographic evidence that wild-type and wv/wv PCs presented similar neurogenetic timetables, as reported. However, the innovative character of this current work lies in the fact that the neurogenetic gradients of wv/wv PCs were not modified from P8 to P90. A tendency for the accumulation of late-formed PCs in the anterior and posterior lobes was found, whereas early-generated PCs were concentrated in the central and inferior lobes. These data suggested that wv/wv PCs may migrate properly to their final destinations. The extrapolation of our results to patients affected with cerebellar ataxias suggests that all cerebellar cortex lobes are affected with several age-dependent alterations in cytoarchitectonics. We also propose that PC loss may be regionally

  4. Deletion of insulin-degrading enzyme elicits antipodal, age-dependent effects on glucose and insulin tolerance.

    Directory of Open Access Journals (Sweden)

    Samer O Abdul-Hay

    Full Text Available BACKGROUND: Insulin-degrading enzyme (IDE is widely recognized as the principal protease responsible for the clearance and inactivation of insulin, but its role in glycemic control in vivo is poorly understood. We present here the first longitudinal characterization, to our knowledge, of glucose regulation in mice with pancellular deletion of the IDE gene (IDE-KO mice. METHODOLOGY: IDE-KO mice and wild-type (WT littermates were characterized at 2, 4, and 6 months of age in terms of body weight, basal glucose and insulin levels, and insulin and glucose tolerance. Consistent with a functional role for IDE in insulin clearance, fasting serum insulin levels in IDE-KO mice were found to be ∼3-fold higher than those in wild-type (WT controls at all ages examined. In agreement with previous observations, 6-mo-old IDE-KO mice exhibited a severe diabetic phenotype characterized by increased body weight and pronounced glucose and insulin intolerance. In marked contrast, 2-mo-old IDE-KO mice exhibited multiple signs of improved glycemic control, including lower fasting glucose levels, lower body mass, and modestly enhanced insulin and glucose tolerance relative to WT controls. Biochemically, the emergence of the diabetic phenotype in IDE-KO mice correlated with age-dependent reductions in insulin receptor (IR levels in muscle, adipose, and liver tissue. Primary adipocytes harvested from 6-mo-old IDE-KO mice also showed functional impairments in insulin-stimulated glucose uptake. CONCLUSIONS: Our results indicate that the diabetic phenotype in IDE-KO mice is not a primary consequence of IDE deficiency, but is instead an emergent compensatory response to chronic hyperinsulinemia resulting from complete deletion of IDE in all tissues throughout life. Significantly, our findings provide new evidence to support the idea that partial and/or transient inhibition of IDE may constitute a valid approach to the treatment of diabetes.

  5. Mössbauer Spectra of Mouse Hearts reveal age-dependent changes in mitochondrial and ferritin iron levels.

    Science.gov (United States)

    Wofford, Joshua D; Chakrabarti, Mrinmoy; Lindahl, Paul Alan

    2017-02-15

    Cardiac function requires continuous high levels of energy, and so iron, a critical player in mitochondrial respiration, is an important component of the heart. Hearts from (57)Fe-enriched mice were evaluated by Mossbauer spectroscopy. Spectra consisted of a sextet and two quadrupole doublets. One doublet was due to residual blood while the other was due to [Fe4S4](2+) clusters and Fe(II) hemes, most of which were associated with mitochondrial respiration. The sextet was due to ferritin; there was no evidence of hemosiderin, a ferritin decomposition product. Iron from ferritin was nearly absent in young hearts, but increased steadily with age. EPR spectra exhibited signals similar to those of brain, liver, and human cells. No age-dependent EPR trends were apparent. Hearts from HFE(-/-) mice with hemochromatosis contained slightly more iron overall than controls, including more ferritin and less mitochondrial iron; these differences typify slightly older hearts, perhaps reflecting the burden due to this disease. HFE(-/-) livers were overloaded with ferritin but had low mitochondrial iron levels. IRP2(-/-) hearts contained less ferritin than controls but normal levels of mitochondrial iron. Hearts of young mice born to an iron-deficient mother contained normal levels of mitochondrial iron and no ferritin; the mothers heart contained low ferritin and normal levels of mitochondrial iron. High-spin Fe(II) ions were nearly undetectable in heart samples; these were evident in brains, livers, and human cells. Previous Mossbauer spectra of unenriched diseased human hearts lacked mitochondrial and blood doublets, and included hemosiderin features. This suggests degradation of iron-containing species during sample preparation.

  6. Age- dependent effect of Alzheimer’s risk variant of CLU on EEG alpha rhythm in non-demented adults

    Directory of Open Access Journals (Sweden)

    Natalya ePonomareva

    2013-12-01

    Full Text Available Polymorphism in the genomic region harboring the CLU gene (rs11136000 has been associated with the risk for Alzheimer’s disease (AD. CLU C allele is assumed to confer risk for AD and the allele T may have a protective effect.We investigated the influence of the AD-associated CLU genotype on a common neurophysiological trait of brain activity (resting-state alpha-rhythm activity in non-demented adults and elucidated whether this influence is modified over the course of aging. We examined quantitative EEG (qEEG in cohort of non-demented individuals (age range 20-80 divided into young (age range 20-50 and old (age range 51-80 cohorts and stratified by CLU polymorphism. To rule out the effect of the ApoE genotype on EEG characteristics, only subjects without the ApoE epsilon4 allele were included in the study.The homozygous presence of the AD risk variant CLU CC in non-demented subjects was associated with an increase of alpha3 absolute power. Moreover, the influence of CLU genotype on alpha3 was found to be higher in the subjects older than 50 years of age. The study also showed age-dependent alterations of alpha topographic distribution that occur independently of the CLU genotype.The increase of upper alpha power has been associated with hippocampal atrophy in patients with mild cognitive impairment (Moretti et al., 2012a. In our study, the CLU CC- dependent increase in upper alpha rhythm, particularly enhanced in elderly non-demented individuals, may imply that the genotype is related to preclinical dysregulation of hippocampal neurophysiology in aging and that this factor may contribute to pathogenesis of AD.

  7. Neurogenesis upregulation on the healthy hemisphere after stroke enhances compensation for age-dependent decrease of basal neurogenesis.

    Science.gov (United States)

    Adamczak, Joanna; Aswendt, Markus; Kreutzer, Christina; Rotheneichner, Peter; Riou, Adrien; Selt, Marion; Beyrau, Andreas; Uhlenküken, Ulla; Diedenhofen, Michael; Nelles, Melanie; Aigner, Ludwig; Couillard-Despres, Sebastien; Hoehn, Mathias

    2017-03-01

    Stroke is a leading cause of death and disability worldwide with no treatment for the chronic phase available. Interestingly, an endogenous repair program comprising inflammation and neurogenesis is known to modulate stroke outcome. Several studies have shown that neurogenesis decreases with age but the therapeutic importance of endogenous neurogenesis for recovery from cerebral diseases has been indicated as its ablation leads to stroke aggravation and worsened outcome. A detailed characterization of the neurogenic response after stroke related to ageing would help to develop novel and targeted therapies. In an innovative approach, we used the DCX-Luc mouse, a transgenic model expressing luciferase in doublecortin-positive neuroblasts, to monitor the neurogenic response following middle cerebral artery occlusion over three weeks in three age groups (2, 6, 12months) by optical imaging while the stroke lesion was monitored by quantitative MRI. The individual longitudinal and noninvasive time profiles provided exclusive insight into age-dependent decrease in basal neurogenesis and neurogenic upregulation in response to stroke which are not accessible by conventional BrdU-based measures of cell proliferation. For cortico-striatal strokes the maximal upregulation occurred at 4days post stroke followed by a continuous decrease to basal levels by three weeks post stroke. Older animals effectively compensated for reduced basal neurogenesis by an enhanced sensitivity to the cerebral lesion, resulting in upregulated neurogenesis levels approaching those measured in young mice. In middle aged and older mice, but not in the youngest ones, additional upregulation of neurogenesis was observed in the contralateral healthy hemisphere. This further substantiates the increased propensity of older brains to respond to lesion situation. Our results clearly support the therapeutic relevance of endogenous neurogenesis for stroke recovery and particularly in older brains.

  8. Age-dependent germline mosaicism of the most common noonan syndrome mutation shows the signature of germline selection.

    Science.gov (United States)

    Yoon, Song-Ro; Choi, Soo-Kung; Eboreime, Jordan; Gelb, Bruce D; Calabrese, Peter; Arnheim, Norman

    2013-06-06

    Noonan syndrome (NS) is among the most common Mendelian genetic diseases (∼1/2,000 live births). Most cases (50%-84%) are sporadic, and new mutations are virtually always paternally derived. More than 47 different sites of NS de novo missense mutations are known in the PTPN11 gene that codes for the protein tyrosine phosphatase SHP-2. Surprisingly, many of these mutations are recurrent with nucleotide substitution rates substantially greater than the genome average; the most common mutation, c.922A>G, is at least 2,400 times greater. We examined the spatial distribution of the c.922A>G mutation in testes from 15 unaffected men and found that the mutations were not uniformly distributed across each testis as would be expected for a mutation hot spot but were highly clustered and showed an age-dependent germline mosaicism. Computational modeling that used different stem cell division schemes confirmed that the data were inconsistent with hypermutation, but consistent with germline selection: mutated spermatogonial stem cells gained an advantage that allowed them to increase in frequency. SHP-2 interacts with the transcriptional activator STAT3. Given STAT3's function in mouse spermatogonial stem cells, we suggest that this interaction might explain the mutant's selective advantage by means of repression of stem cell differentiation signals. Repression of STAT3 activity by cyclin D1 might also play a previously unrecognized role in providing a germline-selective advantage to spermatogonia for the recurrent mutations in the receptor tyrosine kinases that cause Apert syndrome and MEN2B. Looking at recurrent mutations driven by germline selection in different gene families can help highlight common causal signaling pathways.

  9. Phantom jam avoidance through in-car speed advice

    NARCIS (Netherlands)

    Suijs, L.C.W.; Wismans, L.J.J.; Krol, L.; Berkum, van E.C.

    2015-01-01

    The existence of phantom jams can be explained following the definition of Kerner & Konhäuser (1993) who state that a phantom jam occurs without the existence of a physical bottleneck and is caused by the imperfect driving style of road users under metastable traffic conditions. In order to prevent

  10. Copolymer-in-oil phantom materials for elastography.

    Science.gov (United States)

    Oudry, J; Bastard, C; Miette, V; Willinger, R; Sandrin, L

    2009-07-01

    Phantoms that mimic mechanical and acoustic properties of soft biological tissues are essential to elasticity imaging investigation and to elastography device characterization. Several materials including agar/gelatin, polyvinyl alcohol and polyacrylamide gels have been used successfully in the past to produce tissue phantoms, as reported in the literature. However, it is difficult to find a phantom material with a wide range of stiffness, good stability over time and high resistance to rupture. We aim at developing and testing a new copolymer-in-oil phantom material for elastography. The phantom is composed of a mixture of copolymer, mineral oil and additives for acoustic scattering. The mechanical properties of phantoms were evaluated with a mechanical test instrument and an ultrasound-based elastography technique. The acoustic properties were investigated using a through-transmission water-substituting method. We showed that copolymer-in-oil phantoms are stable over time. Their mechanical and acoustic properties mimic those of most soft tissues: the Young's modulus ranges from 2.2-150 kPa, the attenuation coefficient from 0.4-4.0 dB.cm(-1) and the ultrasound speed from 1420-1464 m/s. Their density is equal to 0.90 +/- 0.04 g/cm3. The results suggest that copolymer-in-oil phantoms are attractive materials for elastography.

  11. Phantom Accretion onto the Schwarzschild de-Sitter Black Hole

    Institute of Scientific and Technical Information of China (English)

    M Sharif; G Abbas

    2011-01-01

    We deal with phantom energy accretion onto the Schwarzschild de-Sitter black hole. The energy flux conservation, relativistic Bernoulli equation and mass Bux conservation equation are formulated to discuss the phantom accretion. We discuss the conditions for critical accretion. It is found that the mass of the black hole decreases due to phantom accretion. There exist two critical points which lie in the exterior of horizons (black hole and cosmological horizons). The results for the phantom energy accretion onto the Schwarzschild black hole can be recovered by taking A → 0.%@@ We deal with phantom energy accretion onto the Schwarzschild de-Sitter black hole.The energy flux conserva-tion,relativistic Bernoulli equation and mass flux conservation equation are formulated to discuss the phantom accretion.We discuss the conditions for critical accretion.It is found that the mass of the black hole decreases due to phantom accretion.There exist two critical points which lie in the exterior of horizons(black hole and cosmological horizons).The results for the phantom energy accretion onto the Schwarzschild black hole can be recovered by taking ∧→0.

  12. Comparison of different phantoms used in digital diagnostic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bor, Dogan, E-mail: bor@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics. Tandogan, 06100 Ankara (Turkey); Unal, Elif, E-mail: elf.unall@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey); Uslu, Anil, E-mail: m.aniluslu@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey)

    2015-09-21

    The organs of extremity, chest, skull and lumbar were physically simulated using uniform PMMA slabs with different thicknesses alone and using these slabs together with aluminum plates and air gaps (ANSI Phantoms). The variation of entrance surface air kerma and scatter fraction with X-ray beam qualities was investigated for these phantoms and the results were compared with those measured from anthropomorphic phantoms. A flat panel digital radiographic system was used for all the experiments. Considerable variations of entrance surface air kermas were found for the same organs of different designs, and highest doses were measured for the PMMA slabs. A low contrast test tool and a contrast detail test object (CDRAD) were used together with each organ simulation of PMMA slabs and ANSI phantoms in order to test the clinical image qualities. Digital images of these phantom combinations and anthropomorphic phantoms were acquired in raw and clinically processed formats. Variation of image quality with kVp and post processing was evaluated using the numerical metrics of these test tools and measured contrast values from the anthropomorphic phantoms. Our results indicated that design of some phantoms may not be efficient enough to reveal the expected performance of the post processing algorithms.

  13. Comparison of different phantoms used in digital diagnostic imaging

    Science.gov (United States)

    Bor, Dogan; Unal, Elif; Uslu, Anil

    2015-09-01

    The organs of extremity, chest, skull and lumbar were physically simulated using uniform PMMA slabs with different thicknesses alone and using these slabs together with aluminum plates and air gaps (ANSI Phantoms). The variation of entrance surface air kerma and scatter fraction with X-ray beam qualities was investigated for these phantoms and the results were compared with those measured from anthropomorphic phantoms. A flat panel digital radiographic system was used for all the experiments. Considerable variations of entrance surface air kermas were found for the same organs of different designs, and highest doses were measured for the PMMA slabs. A low contrast test tool and a contrast detail test object (CDRAD) were used together with each organ simulation of PMMA slabs and ANSI phantoms in order to test the clinical image qualities. Digital images of these phantom combinations and anthropomorphic phantoms were acquired in raw and clinically processed formats. Variation of image quality with kVp and post processing was evaluated using the numerical metrics of these test tools and measured contrast values from the anthropomorphic phantoms. Our results indicated that design of some phantoms may not be efficient enough to reveal the expected performance of the post processing algorithms.

  14. Doctors Try Brain-Training to Curb 'Phantom Limb Pain'

    Science.gov (United States)

    ... with the study. "The problem with having a prosthetic limb is that when you try to control that hand, it does not translate. You use other parts ... needed for a patient to move their "phantom" hand, and linked those signals to a robot prosthetic limb. Patients experienced an increase in phantom pain ...

  15. The impact of anthropometric patient-phantom matching on organ dose: A hybrid phantom study for fluoroscopy guided interventions

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Perry B.; Geyer, Amy; Borrego, David; Ficarrotta, Kayla; Johnson, Kevin; Bolch, Wesley E. [Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States); Radiology, University of Florida, Jacksonville, Florida 32209 (United States); Department of Nuclear and Radiological/Biomedical Engineering, University of Florida, Gainesville, Florida 32611-8300 (United States)

    2011-02-15

    Purpose: To investigate the benefits and limitations of patient-phantom matching for determining organ dose during fluoroscopy guided interventions. Methods: In this study, 27 CT datasets representing patients of different sizes and genders were contoured and converted into patient-specific computational models. Each model was matched, based on height and weight, to computational phantoms selected from the UF hybrid patient-dependent series. In order to investigate the influence of phantom type on patient organ dose, Monte Carlo methods were used to simulate two cardiac projections (PA/left lateral) and two abdominal projections (RAO/LPO). Organ dose conversion coefficients were then calculated for each patient-specific and patient-dependent phantom and also for a reference stylized and reference hybrid phantom. The coefficients were subsequently analyzed for any correlation between patient-specificity and the accuracy of the dose estimate. Accuracy was quantified by calculating an absolute percent difference using the patient-specific dose conversion coefficients as the reference. Results: Patient-phantom matching was shown most beneficial for estimating the dose to heavy patients. In these cases, the improvement over using a reference stylized phantom ranged from approximately 50% to 120% for abdominal projections and for a reference hybrid phantom from 20% to 60% for all projections. For lighter individuals, patient-phantom matching was clearly superior to using a reference stylized phantom, but not significantly better than using a reference hybrid phantom for certain fields and projections. Conclusions: The results indicate two sources of error when patients are matched with phantoms: Anatomical error, which is inherent due to differences in organ size and location, and error attributed to differences in the total soft tissue attenuation. For small patients, differences in soft tissue attenuation are minimal and are exceeded by inherent anatomical differences

  16. Automated Voxel-Based Analysis of Volumetric Dynamic Contrast-Enhanced CT Data Improves Measurement of Serial Changes in Tumor Vascular Biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Coolens, Catherine, E-mail: catherine.coolens@rmp.uhn.on.ca [Radiation Medicine Program, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario (Canada); Driscoll, Brandon [Radiation Medicine Program, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario (Canada); Chung, Caroline [Radiation Medicine Program, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Shek, Tina; Gorjizadeh, Alborz [Radiation Medicine Program, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario (Canada); Ménard, Cynthia [Radiation Medicine Program, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Jaffray, David [Radiation Medicine Program, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario (Canada)

    2015-01-01

    Objectives: Development of perfusion imaging as a biomarker requires more robust methodologies for quantification of tumor physiology that allow assessment of volumetric tumor heterogeneity over time. This study proposes a parametric method for automatically analyzing perfused tissue from volumetric dynamic contrast-enhanced (DCE) computed tomography (CT) scans and assesses whether this 4-dimensional (4D) DCE approach is more robust and accurate than conventional, region-of-interest (ROI)-based CT methods in quantifying tumor perfusion with preliminary evaluation in metastatic brain cancer. Methods and Materials: Functional parameter reproducibility and analysis of sensitivity to imaging resolution and arterial input function were evaluated in image sets acquired from a 320-slice CT with a controlled flow phantom and patients with brain metastases, whose treatments were planned for stereotactic radiation surgery and who consented to a research ethics board-approved prospective imaging biomarker study. A voxel-based temporal dynamic analysis (TDA) methodology was used at baseline, at day 7, and at day 20 after treatment. The ability to detect changes in kinetic parameter maps in clinical data sets was investigated for both 4D TDA and conventional 2D ROI-based analysis methods. Results: A total of 7 brain metastases in 3 patients were evaluated over the 3 time points. The 4D TDA method showed improved spatial efficacy and accuracy of perfusion parameters compared to ROI-based DCE analysis (P<.005), with a reproducibility error of less than 2% when tested with DCE phantom data. Clinically, changes in transfer constant from the blood plasma into the extracellular extravascular space (K{sub trans}) were seen when using TDA, with substantially smaller errors than the 2D method on both day 7 post radiation surgery (±13%; P<.05) and by day 20 (±12%; P<.04). Standard methods showed a decrease in K{sub trans} but with large uncertainty (111.6 ± 150.5) %. Conclusions

  17. Regular phantom black holes as gravitational lenses

    CERN Document Server

    Eiroa, Ernesto F

    2015-01-01

    The distortion of the spacetime structure in the surroundings of black holes affects the trajectories of light rays. As a consequence, black holes can act as gravitational lenses. Observations of type Ia supernovas, show that our Universe is in accelerated expansion. The usual explanation is that the Universe is filled with a negative pressure fluid called dark energy, which accounts for 70 % of its total density, which can be modeled by a self-interacting scalar field with a potential. We consider a class of spherically symmetric regular phantom black holes as gravitational lenses. We study large deflection angles, using the strong deflection limit, corresponding to an asymptotic logarithmic approximation. In this case, photons passing close to the photon sphere of the black hole experiment several loops around it before they emerge towards the observer, giving place to two infinite sets of relativistic images. Within this limit, we find analytical expressions for the positions and the magnifications of thes...

  18. Phantom space–times in fake supergravity

    Directory of Open Access Journals (Sweden)

    Maryam Bu Taam

    2015-12-01

    Full Text Available We discuss phantom metrics admitting Killing spinors in fake N=2, D=4 supergravity coupled to vector multiplets. The Abelian U(1 gauge fields in the fake theory have kinetic terms with the wrong sign. We solve the Killing spinor equations for the standard and fake theories in a unified fashion by introducing a parameter which distinguishes between the two theories. The solutions found are fully determined in terms of algebraic conditions, the so-called stabilisation equations, in which the symplectic sections are related to a set of functions. These functions are harmonic in the case of the standard supergravity theory and satisfy the wave-equation in flat (2+1-space–time in the fake theory. Explicit examples are given for the minimal models with quadratic prepotentials.

  19. Phantom percepts: Tinnitus and pain as persisting aversive memory networks

    Science.gov (United States)

    De Ridder, Dirk; Elgoyhen, Ana Belen; Romo, Ranulfo; Langguth, Berthold

    2011-01-01

    Phantom perception refers to the conscious awareness of a percept in the absence of an external stimulus. On the basis of basic neuroscience on perception and clinical research in phantom pain and phantom sound, we propose a working model for their origin. Sensory deafferentation results in high-frequency, gamma band, synchronized neuronal activity in the sensory cortex. This activity becomes a conscious percept only if it is connected to larger coactivated “(self-)awareness” and “salience” brain networks. Through the involvement of learning mechanisms, the phantom percept becomes associated to distress, which in turn is reflected by a simultaneously coactivated nonspecific distress network consisting of the anterior cingulate cortex, anterior insula, and amygdala. Memory mechanisms play a role in the persistence of the awareness of the phantom percept, as well as in the reinforcement of the associated distress. Thus, different dynamic overlapping brain networks should be considered as targets for the treatment of this disorder. PMID:21502503

  20. Crossing of the phantom divide in modified gravity

    CERN Document Server

    Bamba, Kazuharu; Nojiri, Shin'ichi; Odintsov, Sergei D

    2009-01-01

    We reconstruct an explicit model of modified gravity in which a crossing of the phantom divide can be realized. It is shown that the Big Rip singularity appears in the model of modified gravity, whereas that the (finite-time) Big Rip singularity in modified gravity is transformed to the infinite-time singularity in the corresponding scalar field theory obtained through the conformal transformation. Furthermore, we investigate the relations between the scalar field theories realizing a crossing of the phantom divide and the corresponding modified gravitational theories by using the inverse conformal transformation. It is demonstrated that the scalar field theories describing the non-phantom phase (phantom one with the Big Rip) can be represented as the theories of real (complex) $F(R)$ gravity through the inverse (complex) conformal transformation. We also study a viable model of modified gravity in which the transition from the de Sitter universe to the phantom phase can occur.

  1. Surgical phantom for off-pump mitral valve replacement

    Science.gov (United States)

    McLeod, A. Jonathan; Moore, John; Guiraudon, Gerard M.; Jones, Doug L.; Campbell, Gordon; Peters, Terry M.

    2011-03-01

    Off-pump, intracardiac, beating heart surgery has the potential to improve patient outcomes by eliminating the need for cardiopulmonary bypass and aortic cross clamping but it requires extensive image guidance as well as the development of specialized instrumentation. Previously, developments in image guidance and instrumentation were validated on either a static phantom or in vivo through porcine models. This paper describes the design and development of a surgical phantom for simulating off-pump mitral valve replacement inside the closed beating heart. The phantom allows surgical access to the mitral annulus while mimicking the pressure inside the beating heart. An image guidance system using tracked ultrasound, magnetic instrument tracking and preoperative models previously developed for off-pump mitral valve replacement is applied to the phantom. Pressure measurements and ultrasound images confirm the phantom closely mimics conditions inside the beating heart.

  2. Medical images of patients in voxel structures in high resolution for Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Boia, Leonardo S.; Menezes, Artur F.; Silva, Ademir X., E-mail: lboia@con.ufrj.b, E-mail: ademir@con.ufrj.b [Universidade Federal do Rio de Janeiro (PEN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Engenharia Nuclear; Salmon Junior, Helio A. [Clinicas Oncologicas Integradas (COI), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    This work aims to present a computational process of conversion of tomographic and MRI medical images from patients in voxel structures to an input file, which will be manipulated in Monte Carlo Simulation code for tumor's radiotherapic treatments. The problem's scenario inherent to the patient is simulated by such process, using the volume element (voxel) as a unit of computational tracing. The head's voxel structure geometry has voxels with volumetric dimensions around 1 mm{sup 3} and a population of millions, which helps - in that way, for a realistic simulation and a decrease in image's digital process techniques for adjustments and equalizations. With such additional data from the code, a more critical analysis can be developed in order to determine the volume of the tumor, and the protection, beside the patients' medical images were borrowed by Clinicas Oncologicas Integradas (COI/RJ), joined to the previous performed planning. In order to execute this computational process, SAPDI computational system is used in a digital image process for optimization of data, conversion program Scan2MCNP, which manipulates, processes, and converts the medical images into voxel structures to input files and the graphic visualizer Moritz for the verification of image's geometry placing. (author)

  3. Mapping the voxel-wise effective connectome in resting state FMRI.

    Directory of Open Access Journals (Sweden)

    Guo-Rong Wu

    Full Text Available A network approach to brain and dynamics opens new perspectives towards understanding of its function. The functional connectivity from functional MRI recordings in humans is widely explored at large scale, and recently also at the voxel level. The networks of dynamical directed connections are far less investigated, in particular at the voxel level. To reconstruct full brain effective connectivity network and study its topological organization, we present a novel approach to multivariate Granger causality which integrates information theory and the architecture of the dynamical network to efficiently select a limited number of variables. The proposed method aggregates conditional information sets according to community organization, allowing to perform Granger causality analysis avoiding redundancy and overfitting even for high-dimensional and short datasets, such as time series from individual voxels in fMRI. We for the first time depicted the voxel-wise hubs of incoming and outgoing information, called Granger causality density (GCD, as a complement to previous repertoire of functional and anatomical connectomes. Analogies with these networks have been presented in most part of default mode network; while differences suggested differences in the specific measure of centrality. Our findings could open the way to a new description of global organization and information influence of brain function. With this approach is thus feasible to study the architecture of directed networks at the voxel level and individuating hubs by investigation of degree, betweenness and clustering coefficient.

  4. Influence of voxel size settings in X-Ray CT Imagery of soil in scaling properties

    Science.gov (United States)

    Heck, R.; Scaiff, N. T.; Andina, D.; Tarquis, A. M.

    2012-04-01

    Fundamental to the interpretation and comparison of X-ray CT imagery of soil is recognition of the objectivity and consistency of procedures used to generate the 3D models. Notably, there has been a lack of consistency in the size of voxels used for diverse interpretations of soils features and processes; in part, this is due to the ongoing evolution of instrumentation and computerized image processing capacity. Moreover, there is still need for discussion on whether standard voxels sizes should be recommended, and what those would be. Regardless of any eventual adoption of such standards, there is a need to also consider the manner in which voxel size is set in the 3D imagery. In the typical approaches to X-ray CT imaging, voxel size may be set at three stages: image acquisition (involving the position of the sample relative to the tube and detector), image reconstruction (where binning of pixels in the acquired images may occur), as well as post-reconstruction re-sampling (which may involve algorithms such as tri-cubic convolution). This research evaluates and compares the spatial distribution of intra-aggregate voids in 3D imagery as well as their scaling properties, of equivalent voxel size, generated using various combinations of the afore-mentioned approaches. Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. AGL2010-21501/AGR is greatly appreciated.

  5. A visual LISP program for voxelizing AutoCAD solid models

    Science.gov (United States)

    Marschallinger, Robert; Jandrisevits, Carmen; Zobl, Fritz

    2015-01-01

    AutoCAD solid models are increasingly recognized in geological and geotechnical 3D modeling. In order to bridge the currently existing gap between AutoCAD solid models and the grid modeling realm, a Visual LISP program is presented that converts AutoCAD solid models into voxel arrays. Acad2Vox voxelizer works on a 3D-model that is made up of arbitrary non-overlapping 3D-solids. After definition of the target voxel array geometry, 3D-solids are scanned at grid positions and properties are streamed to an ASCII output file. Acad2Vox has a novel voxelization strategy that combines a hierarchical reduction of sampling dimensionality with an innovative use of AutoCAD-specific methods for a fast and memory-saving operation. Acad2Vox provides georeferenced, voxelized analogs of 3D design data that can act as regions-of-interest in later geostatistical modeling and simulation. The Supplement includes sample geological solid models with instructions for practical work with Acad2Vox.

  6. Voxel Based Morphometry Alterations in Mal de Debarquement Syndrome.

    Directory of Open Access Journals (Sweden)

    Yoon-Hee Cha

    Full Text Available Mal de debarquement syndrome (MdDS is a disorder of chronic self-motion perception that occurs though entrainment to rhythmic background motion, such as from sea voyage, and involves the perception of low-frequency rocking that can last for months or years. The neural basis of this persistent sensory perception abnormality is not well understood.We investigated grey matter volume differences underlying persistent MdDS by performing voxel-based morphometry on whole brain and pre-specified ROIs in 28 individuals with MdDS and comparing them to 18 age, sex, and handedness matched controls.MdDS participants exhibited greater grey matter volume in the left inferior parietal lobule, right inferior occipital gyrus (area V3v, right temporal pole, bilateral cerebellar hemispheric lobules VIII/IX and left lobule VIIa/VIIb. Grey matter volumes were lower in bilateral inferior frontal, orbitofrontal, pregenual anterior cingulate cortex (pgACC and left superior medial gyri (t = 3.0, p<0.005uncorr. In ROI analyses, there were no volume differences in the middle occipital gyrus (region of V5/MT or parietal operculum 2 (region of the parietoinsular vestibular cortex. Illness duration was positively related to grey matter volume in bilateral inferior frontal gyrus/anterior insula (IFG/AI, right posterior insula, superior parietal lobule, left middle occipital gyrus (V5/MT, bilateral postcentral gyrus, anterior cerebellum, and left cerebellar hemisphere and vermian lobule IX. In contrast, illness duration was negatively related to volume in pgACC, posterior middle cingulate gyrus (MCC, left middle frontal gyrus (dorsolateral prefrontal cortex-DLPFC, and right cerebellar hemispheric lobule VIIIb (t = 3.0, p<0.005uncorr. The most significant differences were decreased volume in the pgACC and increased volume in the left IFG/AI with longer illness duration (qFDRcorr <0.05. Concurrent medication use did not correlate with these findings or have a relationship with

  7. Phantom breast sensations and phantom breast pain : A 2-year prospective study and a methodological analysis of literature

    NARCIS (Netherlands)

    Dijkstra, P.U.; Rietman, J.S.; Geertzen, J.H.B.

    2007-01-01

    The first aim of this study was to assess prospectively the incidence of phantom breast sensations (PB sensations) and phantom breast pain (PB pain) in a sample of patients treated for breast cancer (n = 204) by means of a modified radical mastectomy (n = 82). Patients were assessed 6 weeks, 6, 12 a

  8. The effect of voxel size on the measurement of mandibular thickness in cone-beam computed tomography

    Directory of Open Access Journals (Sweden)

    Ehsan Hekmatian

    2014-01-01

    Full Text Available Background: Cone-beam computed tomography (CBCT is a new imaging technology that has been widely used in implantology, oral and maxillofacial surgery and orthodontics. This method provides 3-D images that are composed of voxel, which is the smallest image unit, and determines image resolution. Smaller voxel is associated with the higher resolution and also greater radiation exposure. This study was aimed to find out the effect of voxel size on the measurement of mandibular thickness. Materials and Methods: Using voxel sizes of 0.30 mm and 0.15 mm, two CBCT protocols (protocol 1: Field of view (FOV of 15 cm, 85 kVp, 42 mAs, 0.15 mm voxel, 14 s scan time; protocol 2: FOV of 15 cm, 85 kVp, 10 mAs, 0.30 mm voxel, 14 s scan time were carried out on 16 dry human mandibles with permanent dentition. Mandibular thickness was measured at seven different sites (midline region, bilateral canine regions, bilateral mental foramen regions and bilateral molar regions. Analysis of variance was used for analysis of data using the Statistical Package for the Social Sciences version 20 (SPSS Inc., Chicago, IL, USA. P 0.05. Conclusion: Considering the insignificant differences of the mandibular thickness measurements using different voxel sizes, it would be more reasonable to use 0.30 mm voxel size instead of 0.15 mm voxel size to avoid unnecessary radiation exposure.

  9. Happy Birthday, you're Fired! : The Effects of an Age-Dependent Minimum Wage on Youth Employment Flows in the Netherlands

    NARCIS (Netherlands)

    Kabátek, Jan

    2016-01-01

    This paper investigates the effects of the age-dependent minimum wage on youth employment flow in the Netherlands. The Dutch minimum wage for workers aged 15-23 is defined as a step-wise increasing function of a worker's calendar age. At the aged of 23, workers become eligible for the "adult" minimu

  10. Convergence Analysis of Semi-Implicit Euler Methods for Solving Stochastic Age-Dependent Capital System with Variable Delays and Random Jump Magnitudes

    Directory of Open Access Journals (Sweden)

    Qinghui Du

    2014-01-01

    Full Text Available We consider semi-implicit Euler methods for stochastic age-dependent capital system with variable delays and random jump magnitudes, and investigate the convergence of the numerical approximation. It is proved that the numerical approximate solutions converge to the analytical solutions in the mean-square sense under given conditions.

  11. Obesity-induced chronic inflammation in high fat diet challenged C57BL/6J mice is associated with acceleration of age-dependent renal amyloidosis.

    Science.gov (United States)

    van der Heijden, Roel A; Bijzet, Johan; Meijers, Wouter C; Yakala, Gopala K; Kleemann, Robert; Nguyen, Tri Q; de Boer, Rudolf A; Schalkwijk, Casper G; Hazenberg, Bouke P C; Tietge, Uwe J F; Heeringa, Peter

    2015-11-13

    Obesity-induced inflammation presumably accelerates the development of chronic kidney diseases. However, little is known about the sequence of these inflammatory events and their contribution to renal pathology. We investigated the effects of obesity on the evolution of age-dependent renal complications in mice in conjunction with the development of renal and systemic low-grade inflammation (LGI). C57BL/6J mice susceptible to develop age-dependent sclerotic pathologies with amyloid features in the kidney, were fed low (10% lard) or high-fat diets (45% lard) for 24, 40 and 52 weeks. HFD-feeding induced overt adiposity, altered lipid and insulin homeostasis, increased systemic LGI and adipokine release. HFD-feeding also caused renal upregulation of pro-inflammatory genes, infiltrating macrophages, collagen I protein, increased urinary albumin and NGAL levels. HFD-feeding severely aggravated age-dependent structural changes in the kidney. Remarkably, enhanced amyloid deposition rather than sclerosis was observed. The degree of amyloidosis correlated significantly with body weight. Amyloid deposits stained positive for serum amyloid A (SAA) whose plasma levels were chronically elevated in HFD mice. Our data indicate obesity-induced chronic inflammation as a risk factor for the acceleration of age-dependent renal amyloidosis and functional impairment in mice, and suggest that obesity-enhanced chronic secretion of SAA may be the driving factor behind this process.

  12. Age dependency of myocardial triglyceride content. A 3T high-field {sup 1}H-MR spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Petritsch, B.; Gassenmaier, T.; Kunz, A.S.; Donhauser, J.; Bley, T.A.; Horn, M. [University Hospital of Wuerzburg (Germany). Inst. of Diagnostic and Interventional Radiology; Goltz, J.P. [University Hospital of Schleswig-Holstein, Campus Luebeck (Germany). Clinic for Radiology and Nuclear Medicine

    2015-11-15

    The role of myocardial triglyceride (mTG) content in the aging human heart is not entirely understood. The aim of this study was to measure concentrations of mTG content from healthy volunteers and to determine the association between age, mTG content and systolic heart function. Furthermore, the technical stability of the {sup 1}H-magnetic resonance spectroscopy ({sup 1}H-MRS) and the reliability of peak evaluation at 3 T were evaluated. The total study population of 47 healthy volunteers was divided into 4 age classes, according to the age of the subjects (1{sup st} cohort 20-29 years (yrs.), n=20; 2{sup nd} cohort 30-39 yrs., n=10; 3{sup rd} cohort 40-49 yrs., n=9; 4{sup th} cohort 50-60 yrs., n=8). Cardiac MRI and double triggered {sup 1}H-MRS of the myocardium were consecutively performed using a 3 T scanner. Each participant underwent spectroscopic measurements twice in the same investigation. mTG content increases with age. The correlation of age and mTG is minimal (r=0.48; p<0.001). The following age-averaged mTG content values expressed as % of mTG signal compared to the water signal were determined for each cohort: 1{sup st} cohort 0.25 % (± 0.17); 2{sup nd} cohort 0.48 % (± 0.30); 3{sup rd} cohort 0.48 % (± 0.18); 4{sup th} cohort 0.77 % (± 0.70). There was no significant correlation (r=0.04; p=n.s.) between LV mass and mTG content in healthy volunteers. Within our cohorts, no effects of age or mTG content on systolic heart function were seen (r=-0.01; p=n.s.). The intraclass correlation coefficient of spectroscopic measurements was high (r=0.965; p<0.001). Myocardial TG content increases with age. The normal age-dependent concentration ranges of myocardial lipid metabolites reported in this study may be helpful for the correction of acquired {sup 1}H-MRS data in patients when evaluating metabolic and cardiovascular diseases in future magnetic resonance spectroscopy studies.

  13. Refinements on the age-dependent half-life model for estimating child body burdens of polychlorodibenzodioxins and dibenzofurans.

    Science.gov (United States)

    Kerger, Brent D; Leung, Hon-Wing; Scott, Paul K; Paustenbach, Dennis J

    2007-04-01

    We modified our prior age-dependent half-life model to characterize the range of child (ages 0-7) body burdens associated with dietary and environmental exposure to polychlorodibenzodioxins and furans (PCDD/Fs). Several exposure scenarios were evaluated. Infants were assumed to be either breast-fed or formula-fed from birth to 6 months of age. They then received intakes of PCDD/Fs through age 7 from foods based on weighted means estimates [JECFA, 2001. Joint FAO/WHO Committee on Food Additives. Fifty-seventh meeting, Rome, June 5-14 , 2001, pp. 24-40], and with or without exposures (ingestion and dermal) to urban residential soils at 1ppb TCDD toxic equivalents (TEQ). A one-compartment (adipose volume) toxicokinetic model for TCDD described by Kreuzer [Kreuzer, P.F., Csanady, Gy.A., et al., 1997. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and congeners in infants. A toxicokinetic model of human lifetime body burden by TCDD with special emphasis on its uptake by nutrition. Arch. Toxicol. 71, 383-400] was expanded to include the key non-TCDD congeners in human breast milk and adipose tissues, and two model parameter refinements were examined: (1) use of updated and more detailed age-correlated body fat mass data [CDC, 2000. Centers for Disease Control. CDC Growth Charts: United States. Advance Data from Vital and Health Statistics of the Centers for Disease Control and Prevention, National Center for Health Statistics, Number 314, December 2000]; (2) use of breast milk PCDD/F concentration data from sampling completed in 2000-2003 [Wittsiepe, J., Fürst, P., et al., 2004. PCDD/F and dioxin-like PCB in human blood and milk from German mothers. Organohalogen Compd. 66, 2865-2872]. The updated body fat mass data nearly halved the predicted peak body burden for breast-feeding and lowered the time-weighted average (TWA) body burdens from ages 0-7 by 30-40% for breast-fed and formula-fed infants. Combined use of the updated breast milk PCDD/F concentration and body fat

  14. Age-Dependent vasopressinergic modulation of Noc/oFQ-induced impairment of NMDA cerebrovasodilation after brain injury.

    Science.gov (United States)

    Armstead, W M

    2001-06-01

    contributes to the corresponding greater release of NOC/oFQ in the newborn versus the juvenile. Moreover, vasopressin also contributes to the impairment of NMDA cerebrovasodilation after brain injury to a greater extent in newborn versus juveniles. These data suggest that vasopressin modulates NOC/oFQ-induced impairment of NMDA cerebrovasodilation after brain injury in an age-dependent manner.

  15. Age dependent endothelin contribution to NOC/oFQ induced impairment of NMDA cerebrovasodilation after brain injury.

    Science.gov (United States)

    Armstead, W M

    2001-01-01

    contributes to the impairment of NMDA cerebrovasodilation after brain injury to a greater extent in newborns vs juveniles. These data suggest that ET-1 contributes to NOC/oFQ induced impairment of NMDA cerebrovasodilation after brain injury in an age dependent manner.

  16. A Multi-Criteria Framework with Voxel-Dependent Parameters for Radiotherapy Treatment Plan Optimization

    CERN Document Server

    Zarepisheh, Masoud; Li, Nan; Jia, Xun; Jiang, Steve B

    2012-01-01

    In a treatment plan optimization problem for radiotherapy, a clinically acceptable plan is usually generated by an optimization process with weighting factors or reference doses adjusted for organs. Recent discoveries indicate that adjusting parameters associated with each voxel may lead to better plan quality. However, it is still unclear regarding the mathematical reasons behind it. To answer questions related to this problem, we establish in this work a new mathematical framework equipped with two theorems. The new framework clarifies the different consequences of adjusting organ-dependent and voxel-dependent parameters for the treatment plan optimization of radiation therapy, as well as the different effects of adjusting weighting factors versus reference doses in the optimization process. The main discoveries are threefold: 1) While in the organ-based model the selection of the objective function has an impact on the quality of the optimized plans, this is no longer an issue for the voxel-based model sin...

  17. Optimization of Voxelization Parameters in Geant4 Tracking and Improvement of the Shooter Benchmarking Program

    CERN Document Server

    Siegel, Zachary

    2013-01-01

    The geometry-based tracking of the ubiquitous particle physics simulation toolkit Geant4 utilizes the idea of voxels, which effectively partition regions into multi-dimensional slices that can decrease simulation time. The extent of voxelization and the size of the voxels is determined by a set of parameters, which until now, defaulted to arbitrary numbers. In this report I document how I tested different values for these parameters and determined which values should be the default. I modified the existing G01 Geant4 example program to get an initial look at how the performance depended on the parameters. Then I modified the Shooter benchmark program, which lacks extraneous physics processes, to collect more refined data and to provide a tool for future testers to perform comprehensive benchmarks. To this end, I created a new geometry, added features to aid in testing over ranges of parameters, and setup the default tests to provide a good sampling of different simulation scenarios.

  18. 可视人真实可视化的突出进展Voxel-Man(4)%Outstanding Trend of Voxel-Man(4)

    Institute of Scientific and Technical Information of China (English)

    秦笃烈

    2005-01-01

    @@ 3.6 Voxel-Man用于古人类生物学研究 人类生物学研究是另一个方面的应用. 分析和研究人类化石的颅内特征是研究人类进化过程的新领域.利用Voxel-Man处理化石的CT数据集,可以在消除沉积的情况下生成颅骨的完整3D重构,如图72所示.所用的人类颅骨化石取自肯尼亚和坦桑尼亚.这是IDM开辟的医学图像处理的一个新的领域.

  19. Voxel size dependency, reproducibility and sensitivity of an in vivo bone loading estimation algorithm.

    Science.gov (United States)

    Christen, Patrik; Schulte, Friederike A; Zwahlen, Alexander; van Rietbergen, Bert; Boutroy, Stephanie; Melton, L Joseph; Amin, Shreyasee; Khosla, Sundeep; Goldhahn, Jörg; Müller, Ralph

    2016-01-01

    A bone loading estimation algorithm was previously developed that provides in vivo loading conditions required for in vivo bone remodelling simulations. The algorithm derives a bone's loading history from its microstructure as assessed by high-resolution (HR) computed tomography (CT). This reverse engineering approach showed accurate and realistic results based on micro-CT and HR-peripheral quantitative CT images. However, its voxel size dependency, reproducibility and sensitivity still need to be investigated, which is the purpose of this study. Voxel size dependency was tested on cadaveric distal radii with micro-CT images scanned at 25 µm and downscaled to 50, 61, 75, 82, 100, 125 and 150 µm. Reproducibility was calculated with repeated in vitro as well as in vivo HR-pQCT measurements at 82 µm. Sensitivity was defined using HR-pQCT images from women with fracture versus non-fracture, and low versus high bone volume fraction, expecting similar and different loading histories, respectively. Our results indicate that the algorithm is voxel size independent within an average (maximum) error of 8.2% (32.9%) at 61 µm, but that the dependency increases considerably at voxel sizes bigger than 82 µm. In vitro and in vivo reproducibility are up to 4.5% and 10.2%, respectively, which is comparable to other in vitro studies and slightly higher than in other in vivo studies. Subjects with different bone volume fraction were clearly distinguished but not subjects with and without fracture. This is in agreement with bone adapting to customary loading but not to fall loads. We conclude that the in vivo bone loading estimation algorithm provides reproducible, sensitive and fairly voxel size independent results at up to 82 µm, but that smaller voxel sizes would be advantageous.

  20. Characterization of tumor dose heterogeneity for 90Y microsphere therapies using voxel- based dosimetry

    Directory of Open Access Journals (Sweden)

    Justin Mikell

    2014-03-01

    Full Text Available Purpose: Dosimetry for 90Y microsphere therapies (YMT with Standard (SM and Partition (PM models provide only uniform dose estimates to tumor and liver. Our objective is to calculate tumor dose heterogeneity, known to effect response, using voxel-based dosimetry and investigate the limitations of SM and PM.Methods: Voxel-based dosimetry was performed on 17 YMT patients using Monte Carlo DOSXYZnrc. 90Y activity and tissue/density distributions were based on quantitative 90Y bremsstrahlung SPECT/CT. Tumors (n=31, liver, and treatment lobe/segments were segmented on diagnostic CT or MR. Dose volume histograms (DVH were created for tumors and normal liver. Bland-Altman analysis compared voxel-based mean absorbed doses to tumor and liver with SM and PM. Tumor and normal liver absorbed dose heterogeneity were investigated through metrics: integral uniformity (IU, D10/D90, COV. Correlations of heterogeneity with voxel-based mean doses and volumes were evaluated.Results: Heterogeneity metrics (mean ± 1σ for tumor dose were COV = 0.48 ± 0.28, D10/D90 = 4.7 ± 3.9, and IU = 0.8 ± 0.18. Heterogeneity metrics correlated with tumor volume (r > 0.58 but not tumor mean doses (r < 0.20. Voxel-based tumor mean doses correlated with PM (r = 0.84 but not SM (r = 0.08. Both yielded poor limits of agreement with of 83 ± 174 and -28 ± 181 Gy, respectively. Normal liver heterogeneity metrics (mean ± 1σ were COV = 0.83 ± 0.29, D10/D90 = 12 ± 15, and IU = 0.97 ± 0.03. Only D10/D90 (r = 0.49 correlated with mean normal liver absorbed dose. Voxel-based normal liver/lobe mean doses correlated with PM (r = 0.96, but had poor limits of agreement (26 ± 29 Gy.Conclusion: Tumor doses have high levels of heterogeneity that increase with volume but are independent of dose. Voxel-based DVH and dose heterogeneity metrics will promote accurate characterization of tumor response following YMT.--------------------------------------Cite this article as: Mikell J, Mourtada F

  1. Automating the segmentation of medical images for the production of voxel tomographic computational models.

    Science.gov (United States)

    Caon, M; Mohyla, J

    2001-12-01

    Radiation dosimetry for the diagnostic medical imaging procedures performed on humans requires anatomically accurate, computational models. These may be constructed from medical images as voxel-based tomographic models. However, they are time consuming to produce and as a consequence, there are few available. This paper discusses the emergence of semi-automatic segmentation techniques and describes an application (iRAD) written in Microsoft Visual Basic that allows the bitmap of a medical image to be segmented interactively and semi-automatically while displayed in Microsoft Excel. iRAD will decrease the time required to construct voxel models.

  2. The Relevance Voxel Machine (RVoxM): A Bayesian Method for Image-Based Prediction

    DEFF Research Database (Denmark)

    Sabuncu, Mert R.; Van Leemput, Koen

    2011-01-01

    to utilize a small number of spatially clustered sets of voxels that are particularly suited for clinical interpretation. RVoxM automatically tunes all its free parameters during the training phase, and offers the additional advantage of producing probabilistic prediction outcomes. Experiments on age......This paper presents the Relevance VoxelMachine (RVoxM), a Bayesian multivariate pattern analysis (MVPA) algorithm that is specifically designed for making predictions based on image data. In contrast to generic MVPA algorithms that have often been used for this purpose, the method is designed...... prediction from structural brain MRI indicate that RVoxM yields biologically meaningful models that provide excellent predictive accuracy....

  3. Puzzles of the dark energy in the universe - phantom

    CERN Document Server

    Dabrowski, Mariusz P

    2014-01-01

    This paper is devoted to some simple approach based on general physics tools to describe the physical properties of a hypothetical particle which can be the source of dark energy in the Universe known as phantom. Phantom is characterized by the fact that it possesses negative momentum and kinetic energy and that it gives large negative pressure which acts as antigravity. We consider phantom harmonic oscillator in comparison to a standard harmonic oscillator. By using the first law of thermodynamics we explain why the energy density of the Universe grows when it is filled with phantom. We also show how the collision of phantom with a standard particle leads to exploration of energy from the former by the latter (i.e. from phantom to the standard) if their masses are different. The most striking of our conclusions is that the collision of phantom and standard particles of the same masses is impossible unless both of them are at rest and suddenly start moving with the opposite velocities and kinetic energies. Th...

  4. Studies on Phantom Vibration and Ringing Syndrome among Postgraduate Students

    Directory of Open Access Journals (Sweden)

    Atul Kumar Goyal

    2015-03-01

    Full Text Available Phantom vibrations and ringing of mobile phones are prevalent hallucinations in the general population. They might be considered as a normal brain mechanism. The aim of this study was to establish the prevalence of Phantom vibrations and ringing syndrome among students and to assess factors associated it. The survey of 300 postgraduate students belonging to different field of specialization was conducted at Kurukshetra University. 74% of students were found to have both Phantom vibrations and ringing syndrome. Whereas 17% of students felt Phantom vibration exclusively and 4% students face only Phantom ringing syndrome. Both the syndrome occurs more fervent in students who kept their mobile phone in shirt or jean pocket than to who kept mobile in handbag. 75% of students felt vibration or ringing even when the phone is switched off or phone was not in their pocket. Also the frequency of both the syndrome is directly proportional to the duration of mobile phone use and person emotional behavior. Although most of students agree that the Phantom syndrome did not bother them but some students deals with anxiety when they feel symptoms associated with Phantom syndrome. By using mobile phones in proper way, one can avoid these syndromes, or at least can ameliorate the symptoms.

  5. Thermal human phantom for testing of millimeter wave cameras

    Science.gov (United States)

    Palka, Norbert; Ryniec, Radoslaw; Piszczek, Marek; Szustakowski, Mieczyslaw; Zyczkowski, Marek; Kowalski, Marcin

    2012-06-01

    Screening cameras working in millimetre band gain more and more interest among security society mainly due to their capability of finding items hidden under clothes. Performance of commercially available passive cameras is still limited due to not sufficient resolution and contrast in comparison to other wavelengths (visible or infrared range). Testing of such cameras usually requires some persons carrying guns, bombs or knives. Such persons can have different clothes or body temperature, what makes the measurements even more ambiguous. To avoid such situations we built a moving phantom of human body. The phantom consists of a polystyrene manikin which is covered with a number of small pipes with water. Pipes were next coated with a silicone "skin". The veins (pipes) are filled with water heated up to 37 C degrees to obtain the same temperature as human body. The phantom is made of non-metallic materials and is placed on a moving wirelessly-controlled platform with four wheels. The phantom can be dressed with a set of ordinary clothes and can be equipped with some dangerous (guns, bombs) and non-dangerous items. For tests we used a passive commercially available camera TS4 from ThruVision Systems Ltd. operating at 250 GHz. We compared the images taken from phantom and a man and we obtained good similarity both for naked as well as dressed man/phantom case. We also tested the phantom with different sets of clothes and hidden items and we got good conformity with persons.

  6. Phantom jam avoidance through in-car speed advice

    OpenAIRE

    Suijs, L.C.W.; Wismans, L.J.J.; Krol, L.; Berkum, van, E.C.

    2015-01-01

    The existence of phantom jams can be explained following the definition of Kerner & Konhäuser (1993) who state that a phantom jam occurs without the existence of a physical bottleneck and is caused by the imperfect driving style of road users under metastable traffic conditions. In order to prevent a phantom jams to occur, one can either focus on the cause of the perturbation, or on the metastability of the traffic flow. Previous studies have shown that the use of dynamic speed limits, displa...

  7. Anisotropic phantom to calibrate high-q diffusion MRI methods

    Science.gov (United States)

    Komlosh, M. E.; Benjamini, D.; Barnett, A. S.; Schram, V.; Horkay, F.; Avram, A. V.; Basser, P. J.

    2017-02-01

    A silicon oil-filled glass capillary array is proposed as an anisotropic diffusion MRI phantom. Together with a computational/theoretical pipeline these provide a gold standard for calibrating and validating high-q diffusion MRI experiments. The phantom was used to test high angular resolution diffusion imaging (HARDI) and double pulsed-field gradient (d-PFG) MRI acquisition schemes. MRI-based predictions of microcapillary diameter using both acquisition schemes were compared with results from optical microscopy. This phantom design can be used for quality control and quality assurance purposes and for testing and validating proposed microstructure imaging experiments and the processing pipelines used to analyze them.

  8. Water equivalent phantom materials for 192Ir brachytherapy

    Science.gov (United States)

    Schoenfeld, Andreas A.; Harder, Dietrich; Poppe, Björn; Chofor, Ndimofor

    2015-12-01

    Several solid phantom materials have been tested regarding their suitability as water substitutes for dosimetric measurements in brachytherapy with 192Ir as a typical high energy photon emitter. The radial variations of the spectral photon fluence, of the total, primary and scattered photon fluence and of the absorbed dose to water in the transversal plane of the tested cylindrical phantoms surrounding a centric and coaxially arranged Varian GammaMed afterloading 192Ir brachytherapy source were Monte-Carlo simulated in EGSnrc. The degree of water equivalence of a phantom material was evaluated by comparing the radial dose-to-water profile in the phantom material with that in water. The phantom size was varied over a large range since it influences the dose contribution by scattered photons with energies diminished by single and multiple Compton scattering. Phantom axis distances up to 10 cm were considered as clinically relevant. Scattered photons with energies reaching down into the 25 keV region dominate the photon fluence at source distances exceeding 3.5 cm. The tested phantom materials showed significant differences in the degree of water equivalence. In phantoms with radii up to 10 cm, RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, and Plastic Water LR phantoms show excellent water equivalence with dose deviations from a water phantom not exceeding 0.8%, while Original Plastic Water (as of 2015), Plastic Water (1995), Blue Water, polyethylene, and polystyrene show deviations up to 2.6%. For larger phantom radii up to 30 cm, the deviations for RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, and Plastic Water LR remain below 1.4%, while Original Plastic Water (as of 2015), Plastic Water (1995), Blue Water, polyethylene, and polystyrene produce deviations up to 8.1%. PMMA plays a separate role, with deviations up to 4.3% for radii not exceeding 10 cm, but below 1% for radii up to 30 cm. As suggested by

  9. Color-matched esophagus phantom for fluorescent imaging

    Science.gov (United States)

    Yang, Chenying; Hou, Vivian; Nelson, Leonard Y.; Seibel, Eric J.

    2013-02-01

    We developed a stable, reproducible three-dimensional optical phantom for the evaluation of a wide-field endoscopic molecular imaging system. This phantom mimicked a human esophagus structure with flexibility to demonstrate body movements. At the same time, realistic visual appearance and diffuse spectral reflectance properties of the tissue were simulated by a color matching methodology. A photostable dye-in-polymer technology was applied to represent biomarker probed "hot-spot" locations. Furthermore, fluorescent target quantification of the phantom was demonstrated using a 1.2mm ultrathin scanning fiber endoscope with concurrent fluorescence-reflectance imaging.

  10. Neutron Field Measurements in Phantom with Foil Activation Methods.

    Science.gov (United States)

    1986-11-29

    jI25 Ii III uumu ullli~ S....- - Lb - w * .qJ’ AD-A 192 122 ulJ. IL (pj DNA-TR-87- 10 N EUTRON FIELD MEASUREMENTS IN PHANTOM WITH FOIL ACTIVATION...SAND II Measurements in Phantom 6 4 The 5-Foil Neutron Dosimetry Method 29 5 Comparison of SAND II and Simple 5-Foil Dosimetry Method 34 6 Thermal ...quite reasonable. The monkey phantom spectrum differs from the NBS U-235 fission spectrum in that the former has a I/E tail plus thermal -neutron peak

  11. Cosmological perturbations on the Phantom brane

    CERN Document Server

    Bag, Satadru; Shtanov, Yuri; Sahni, Varun

    2016-01-01

    We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, $w_{\\rm eff} < -1$, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom - the 'Weyl fluid' or 'dark radiation'. Setting initial conditions on super-Hubble spatial scales at the epoch of radiation domination, we evolve perturbations of radiation, pressureless matter and the Weyl fluid until the present epoch. We observe a gradual decrease in the amplitude of the Weyl-fluid perturbations after Hubble-radius crossing, which results in a negligible effect of the Weyl fluid on the evolution of matter perturbations on spatial scales relevant for structure formation. Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on...

  12. SU-E-I-60: Quality Assurance Testing Methods and Customized Phantom for Magnetic Resonance Imaging and Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Song, K-H; Lee, D-W; Choe, B-Y [Department of Biomedical Engineering, Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, Seoul (Korea, Republic of)

    2015-06-15

    Purpose: The objectives of this study are to develop an magnetic resonance imaging and spectroscopy (MRI-MRS) fused phantom along with the inserts for metabolite quantification and to conduct quantitative analysis and evaluation of the layered vials of brain-mimicking solution for quality assurance (QA) performance, according to the localization sequence. Methods: The outer cylindrical phantom body is made of acrylic materials. The section other than where the inner vials are located was filled with copper sulfate and diluted with water so as to reduce the T1 relaxation time. Sodium chloride was included to provide conductivity similar to the human body. All measurements of MRI and MRS were made using a 3.0 T scanner (Achiva Tx 3.0 T; Philips Medical Systems, Netherlands). The MRI scan parameters were as follows: (1) spin echo (SE) T1-weighted image: repetition time (TR), 500ms; echo time (TE), 20ms; matrix, 256×256; field of view (FOV), 250mm; gap, 1mm; number of signal averages (NSA), 1; (2) SE T2-weighted image: TR, 2,500 ms; TE, 80 ms; matrix, 256×256; FOV, 250mm; gap, 1mm; NSA, 1; 23 slice images were obtained with slice thickness of 5mm. The water signal of each volume of interest was suppressed by variable pulse power and optimized relaxation delays (VAPOR) applied before the scan. By applying a point-resolved spectroscopy sequence, the MRS scan parameters were as follows: voxel size, 0.8×0.8×0.8 cm{sup 3}; TR, 2,000ms; TE, 35ms; NSA, 128. Results: Using the fused phantom, the results of measuring MRI factors were: geometric distortion, <2% and ±2 mm; image intensity uniformity, 83.09±1.33%; percent-signal ghosting, 0.025±0.004; low-contrast object detectability, 27.85±0.80. In addition, the signal-to-noise ratio of N-acetyl-aspartate was consistently high (42.00±5.66). Conclusion: The MRI-MRS QA factors obtained simultaneously using the phantom can facilitate evaluation of both images and spectra, and provide guidelines for obtaining MRI and MRS QA

  13. [Phantoms for the collection of genital secretions in stallions].

    Science.gov (United States)

    Klug, E; Brinkhoff, D; Flüge, A; Scherbarth, R; Essich, G; Kienzler, M

    1977-10-01

    Practical experiences of the phantom method for collection of genital secretions from stallions are reported. Taking a phantom used in the Richard-Götze-Haus Tierärztliche Hochschule Hannover as a prototype two further models slightly modified have been constructed, baring a flat hollow in the right side of the caudal phantom body for manual inserting of the Artificial Vagina. These three models fulfill four important conditions for routine use: (1) sufficient sexual attractivity for the stallions; 80-85% successful collections of presecretions out of a total of 1050 using the dummy and 70% successful semen collections from more than 240 in total; (2) solid and resistant construction; (3) easy cleaning and desinfection of the surface of the phantom to get representative samples; (4) firm installation on a hygienic floor.

  14. Suggested guidelines for treatment of phantom limb pain.

    Science.gov (United States)

    Sherman, R A; Tippens, J K

    1982-12-01

    Eighty to ninety percent of amputees have been shown to suffer significant amounts of phantom limb pain in contrast to the widely accepted level of about 5%. Surveys of the literature, of physicians actively treating phantom pain, and of over 3,000 American veteran amputees have shown that most of the usual treatments are not efficacious when followups of a year or more are done. A diagnostic and therapeutic schemata is presented, which incorporates the above surveys, research, and clinical experience into a unified approach optimizing the few treatments showing a reasonable hope of long term success. Every effort is made to identify the source of pain being referred into the phantom. Stump, back, prosthetic, and other physical problems are corrected prior to initiation of other treatments, including EMG or temperature feedback from the stump, sympathetic system alteration, modulation of anxiety and depression, TENS, and ultrasound. Key indexing terms: phantom pain, treatment, amputees, referred pain.

  15. Thermodynamics in $F(R)$ gravity with phantom crossing

    CERN Document Server

    Bamba, Kazuharu

    2009-01-01

    We study thermodynamics of the apparent horizon in $F(R)$ gravity. In particular, we demonstrate that a $F(R)$ gravity model with realizing a crossing of the phantom divide can satisfy the second law of thermodynamics.

  16. Phantom crossing in viable $f(R)$ theories

    CERN Document Server

    Bamba, Kazuharu; Lee, Chung-Chi

    2011-01-01

    We review the equation of state for dark energy in modified gravity theories. In particular, we summarize the generic feature of the phantom divide crossing in the past and future in viable $f(R)$ gravity models.

  17. Fabrication and characterization of phantoms made of polydimethylsiloxane (PDMS)

    Science.gov (United States)

    Villanueva-Luna, A. E.; Santiago-Alvarado, A.; Castro-Ramos, J.; Licona-Moran, B.; Vazquez-Montiel, S.; Flores-Gil, A.; Delgado-Atencio, J. A.

    2011-03-01

    The transparent elastomer Polydimethylsiloxane (PDMS) Sylgard 184 is increasingly used in optical applications, as in the manufacture of microlens, waveguides (optical fibers) and to elaborated phantoms (simulator of biological tissue); The wide range of applications is due to its excellent physic-chemical properties, its low cost, easy operation and null toxicity. This paper describes the manufacturing process and physic-chemical characterization of Phantoms prepared with PDMS as grid and doped with some elements present as Gliceryl, ink, glucose 10% and melanin provided by sigma aldrich. We made phantoms with different concentrations and elements; we measured their profiles, and thicknesses. Finally, we obtained their Raman Spectra. We present the experimental results obtained of the physic-chemical parameters of the phantoms and the conclusions.

  18. Bioassay Phantoms Using Medical Images and Computer Aided Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Dr. X. Geroge Xu

    2011-01-28

    A radiation bioassay program relies on a set of standard human phantoms to calibrate and assess radioactivity levels inside a human body for radiation protection and nuclear medicine imaging purposes. However, the methodologies in the development and application of anthropomorphic phantoms, both physical and computational, had mostly remained the same for the past 40 years. We herein propose a 3-year research project to develop medical image-based physical and computational phantoms specifically for radiation bioassay applications involving internally deposited radionuclides. The broad, long-term objective of this research was to set the foundation for a systematic paradigm shift away from the anatomically crude phantoms in existence today to realistic and ultimately individual-specific bioassay methodologies. This long-term objective is expected to impact all areas of radiation bioassay involving nuclear power plants, U.S. DOE laboratories, and nuclear medicine clinics.

  19. A generalization of voxel-wise procedures for highdimensional statistical inference using ridge regression

    DEFF Research Database (Denmark)

    Sjöstrand, Karl; Cardenas, Valerie A.; Larsen, Rasmus;

    2008-01-01

    regression to address this issue, allowing for a gradual introduction of correlation information into the model. We make the connections between ridge regression and voxel-wise procedures explicit and discuss relations to other statistical methods. Results are given on an in-vivo data set of deformation...

  20. Voxel Advanced Digital-Manufacturing for Earth and Regolith in Space Project

    Science.gov (United States)

    Zeitlin, Nancy; Mueller, Robert P.

    2015-01-01

    A voxel is a discrete three-dimensional (3D) element of material that is used to construct a larger 3D object. It is the 3D equivalent of a pixel. This project will conceptualize and study various approaches in order to develop a proof of concept 3D printing device that utilizes regolith as the material of the voxels. The goal is to develop a digital printer head capable of placing discrete self-aligning voxels in additive layers in order to fabricate small parts that can be given structural integrity through a post-printing sintering or other binding process. The quicker speeds possible with the voxel 3D printing approach along with the utilization of regolith material as the substrate will advance the use of this technology to applications for In-Situ Resource Utilization (ISRU), which is key to reducing logistics from Earth to Space, thus making long-duration human exploration missions to other celestial bodies more possible.

  1. List-mode image reconstruction for positron emission tomography using tetrahedral voxels

    Science.gov (United States)

    Gillam, John E.; Angelis, Georgios I.; Meikle, Steven R.

    2016-09-01

    Image space decomposition based on tetrahedral voxels are interesting candidates for use in emission tomography. Tetrahedral voxels provide many of the advantages of point clouds with irregular spacing, such as being intrinsically multi-resolution, yet they also serve as a volumetric partition of the image space and so are comparable to more standard cubic voxels. Additionally, non-rigid displacement fields can be applied to the tetrahedral mesh in a straight-forward manner. So far studies incorporating tetrahedral decomposition of the image space have concentrated on pre-calculated, node-based, system matrix elements which reduces the flexibility of the tetrahedral approach and the capacity to accurately define regions of interest. Here, a list-mode on-the-fly calculation of the system matrix elements is described using a tetrahedral decomposition of the image space and volumetric elements—voxels. The algorithm is demonstrated in the context of awake animal PET which may require both rigid and non-rigid motion compensation, as well as quantification within small regions of the brain. This approach allows accurate, event based, motion compensation including non-rigid deformations.

  2. Advances in constructing regional geological voxel models, illustrated by their application in aggregate resource assessments

    NARCIS (Netherlands)

    Maljers, D.; Stafleu, J.; Meulen, M.J. van der; Dambrink, R.M.

    2015-01-01

    Aggregate resource assessments, derived from three subsequent generations of voxel models, were compared in a qualitative way to illustrate and discuss modelling progress. We compared the models in terms of both methodology and usability. All three models were produced by the Geological Survey of th

  3. Select and Cluster: A Method for Finding Functional Networks of Clustered Voxels in fMRI

    Science.gov (United States)

    DonGiovanni, Danilo

    2016-01-01

    Extracting functional connectivity patterns among cortical regions in fMRI datasets is a challenge stimulating the development of effective data-driven or model based techniques. Here, we present a novel data-driven method for the extraction of significantly connected functional ROIs directly from the preprocessed fMRI data without relying on a priori knowledge of the expected activations. This method finds spatially compact groups of voxels which show a homogeneous pattern of significant connectivity with other regions in the brain. The method, called Select and Cluster (S&C), consists of two steps: first, a dimensionality reduction step based on a blind multiresolution pairwise correlation by which the subset of all cortical voxels with significant mutual correlation is selected and the second step in which the selected voxels are grouped into spatially compact and functionally homogeneous ROIs by means of a Support Vector Clustering (SVC) algorithm. The S&C method is described in detail. Its performance assessed on simulated and experimental fMRI data is compared to other methods commonly used in functional connectivity analyses, such as Independent Component Analysis (ICA) or clustering. S&C method simplifies the extraction of functional networks in fMRI by identifying automatically spatially compact groups of voxels (ROIs) involved in whole brain scale activation networks. PMID:27656202

  4. Anatomical specificity of vascular endothelial growth factor expression in glioblastomas: a voxel-based mapping analysis

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xing [Capital Medical University, Department of Neurosurgery, Beijing Tiantan Hospital, Beijing (China); Wang, Yinyan [Capital Medical University, Department of Neurosurgery, Beijing Tiantan Hospital, Beijing (China); Capital Medical University, Department of Neuropathology, Beijing Neurosurgical Institute, Beijing (China); Wang, Kai; Ma, Jun; Li, Shaowu [Capital Medical University, Department of Neuroradiology, Beijing Tiantan Hospital, Beijing (China); Liu, Shuai [Chinese Academy of Medical Sciences and Peking Union Medical College, Departments of Neurosurgery, Peking Union Medical College Hospital, Beijing (China); Liu, Yong [Chinese Academy of Sciences, Brainnetome Center, Institute of Automation, Beijing (China); Jiang, Tao [Capital Medical University, Department of Neurosurgery, Beijing Tiantan Hospital, Beijing (China); Beijing Academy of Critical Illness in Brain, Department of Clinical Oncology, Beijing (China)

    2016-01-15

    The expression of vascular endothelial growth factor (VEGF) is a common genetic alteration in malignant gliomas and contributes to the angiogenesis of tumors. This study aimed to investigate the anatomical specificity of VEGF expression levels in glioblastomas using voxel-based neuroimaging analysis. Clinical information, MR scans, and immunohistochemistry stains of 209 patients with glioblastomas were reviewed. All tumor lesions were segmented manually and subsequently registered to standard brain space. Voxel-based regression analysis was performed to correlate the brain regions of tumor involvement with the level of VEGF expression. Brain regions identified as significantly associated with high or low VEGF expression were preserved following permutation correction. High VEGF expression was detected in 123 (58.9 %) of the 209 patients. Voxel-based statistical analysis demonstrated that high VEGF expression was more likely in tumors located in the left frontal lobe and the right caudate and low VEGF expression was more likely in tumors that occurred in the posterior region of the right lateral ventricle. Voxel-based neuroimaging analysis revealed the anatomic specificity of VEGF expression in glioblastoma, which may further our understanding of genetic heterogeneity during tumor origination. This finding provides primary theoretical support for potential future application of customized antiangiogenic therapy. (orig.)

  5. Sparse and Adaptive Diffusion Dictionary (SADD) for recovering intra-voxel white matter structure.

    Science.gov (United States)

    Aranda, Ramon; Ramirez-Manzanares, Alonso; Rivera, Mariano

    2015-12-01

    On the analysis of the Diffusion-Weighted Magnetic Resonance Images, multi-compartment models overcome the limitations of the well-known Diffusion Tensor model for fitting in vivo brain axonal orientations at voxels with fiber crossings, branching, kissing or bifurcations. Some successful multi-compartment methods are based on diffusion dictionaries. The diffusion dictionary-based methods assume that the observed Magnetic Resonance signal at each voxel is a linear combination of the fixed dictionary elements (dictionary atoms). The atoms are fixed along different orientations and diffusivity profiles. In this work, we present a sparse and adaptive diffusion dictionary method based on the Diffusion Basis Functions Model to estimate in vivo brain axonal fiber populations. Our proposal overcomes the following limitations of the diffusion dictionary-based methods: the limited angular resolution and the fixed shapes for the atom set. We propose to iteratively re-estimate the orientations and the diffusivity profile of the atoms independently at each voxel by using a simplified and easier-to-solve mathematical approach. As a result, we improve the fitting of the Diffusion-Weighted Magnetic Resonance signal. The advantages with respect to the former Diffusion Basis Functions method are demonstrated on the synthetic data-set used on the 2012 HARDI Reconstruction Challenge and in vivo human data. We demonstrate that improvements obtained in the intra-voxel fiber structure estimations benefit brain research allowing to obtain better tractography estimations. Hence, these improvements result in an accurate computation of the brain connectivity patterns.

  6. Evaluation of voxel-based rendering of high resolution surface descriptions

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Olesen, Søren Krarup; Markovic, Milos

    2014-01-01

    resolution scans of the room surfaces as basis for the room models. In the present work this approach is evaluated with a voxel-based method (described in earlier publications), and compared to measured impulse responses. The results are compared objectively by visual inspection of the impulse responses...

  7. Two-tensor streamline tractography through white matter intra-voxel fiber crossings

    DEFF Research Database (Denmark)

    Qazi, Arish Asif; Kindlmann, G; O'Donnell, L;

    2008-01-01

    An inherent drawback of the traditional diffusion tensor model is its limited ability to provide detailed information about multidirectional fiber architecture within a voxel. This leads to erroneous fiber tractography results in locations where fiber bundles cross each other. In this paper, we...

  8. Physically constrained voxel-based penalty adaptation for ultra-fast IMRT planning.

    Science.gov (United States)

    Wahl, Niklas; Bangert, Mark; Kamerling, Cornelis P; Ziegenhein, Peter; Bol, Gijsbert H; Raaymakers, Bas W; Oelfke, Uwe

    2016-07-08

    Conventional treatment planning in intensity-modulated radiation therapy (IMRT) is a trial-and-error process that usually involves tedious tweaking of optimization parameters. Here, we present an algorithm that automates part of this process, in particular the adaptation of voxel-based penalties within normal tissue. Thereby, the proposed algorithm explicitly considers a priori known physical limitations of photon irradiation. The efficacy of the developed algorithm is assessed during treatment planning studies comprising 16 prostate and 5 head and neck cases. We study the eradication of hot spots in the normal tissue, effects on target coverage and target conformity, as well as selected dose volume points for organs at risk. The potential of the proposed method to generate class solutions for the two indications is investigated. Run-times of the algorithms are reported. Physically constrained voxel-based penalty adaptation is an adequate means to automatically detect and eradicate hot-spots during IMRT planning while maintaining target coverage and conformity. Negative effects on organs at risk are comparably small and restricted to lower doses. Using physically constrained voxel-based penalty adaptation, it was possible to improve the generation of class solutions for both indications. Considering the reported run-times of less than 20 s, physically constrained voxel-based penalty adaptation has the potential to reduce the clinical workload during planning and automated treatment plan generation in the long run, facilitating adaptive radiation treatments.

  9. Neural Correlates of Communication Skill and Symptom Severity in Autism: A Voxel-Based Morphometry Study

    Science.gov (United States)

    Parks, Lauren K.; Hill, Dina E.; Thoma, Robert J.; Euler, Matthew J.; Lewine, Jeffrey D.; Yeo, Ronald A.

    2009-01-01

    Although many studies have compared the brains of normal controls and individuals with autism, especially older, higher-functioning individuals with autism, little is known of the neural correlates of the vast clinical heterogeneity characteristic of the disorder. In this study, we used voxel-based morphometry (VBM) to examine gray matter…

  10. Part-type Segmentation of Articulated Voxel-Shapes using the Junction Rule

    NARCIS (Netherlands)

    Reniers, Dennie; Telea, Alexandru

    2008-01-01

    We present a part-type segmentation method for articulated voxel-shapes based on curve skeletons. Shapes are considered to consist of several simpler, intersecting shapes. Our method is based on the junction rule : the observation that two intersecting shapes generate an additional junction in their

  11. Patch-type Segmentation of Voxel Shapes using Simplified Surface Skeletons

    NARCIS (Netherlands)

    Reniers, Dennie; Telea, Alexandru

    2008-01-01

    We present a new method for decomposing a 3D voxel shape into disjoint segments using the shape’s simplified surface-skeleton. The surface skeleton of a shape consists of 2D manifolds inside its volume. Each skeleton point has a maximally inscribed ball that touches the boundary in at least two cont

  12. Part-type Segmentation of Articulated Voxel-Shapes using the Junction Rule

    NARCIS (Netherlands)

    Reniers, Dennie; Telea, Alexandru

    2008-01-01

    We present a part-type segmentation method for articulated voxel-shapes based on curve skeletons. Shapes are considered to consist of several simpler, intersecting shapes. Our method is based on the junction rule: the observation that two intersecting shapes generate an additional junction in their

  13. Alpha image reconstruction (AIR): A new iterative CT image reconstruction approach using voxel-wise alpha blending

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Christian [Institute of Medical Physics, Friedrich-Alexander University (FAU), Erlangen 91052 (Germany); Sawall, Stefan; Knaup, Michael [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg 69120 (Germany); Kachelrieß, Marc, E-mail: marc.kachelriess@dkfz-heidelberg [Institute of Medical Physics, Friedrich-Alexander University (FAU), Erlangen 91052, Germany and Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg 69120 (Germany)

    2014-06-15

    Purpose: Iterative image reconstruction gains more and more interest in clinical routine, as it promises to reduce image noise (and thereby patient dose), to reduce artifacts, or to improve spatial resolution. Among vendors and researchers, however, there is no consensus of how to best achieve these aims. The general approach is to incorporatea priori knowledge into iterative image reconstruction, for example, by adding additional constraints to the cost function, which penalize variations between neighboring voxels. However, this approach to regularization in general poses a resolution noise trade-off because the stronger the regularization, and thus the noise reduction, the stronger the loss of spatial resolution and thus loss of anatomical detail. The authors propose a method which tries to improve this trade-off. The proposed reconstruction algorithm is called alpha image reconstruction (AIR). One starts with generating basis images, which emphasize certain desired image properties, like high resolution or low noise. The AIR algorithm reconstructs voxel-specific weighting coefficients that are applied to combine the basis images. By combining the desired properties of each basis image, one can generate an image with lower noise and maintained high contrast resolution thus improving the resolution noise trade-off. Methods: All simulations and reconstructions are performed in native fan-beam geometry. A water phantom with resolution bar patterns and low contrast disks is simulated. A filtered backprojection (FBP) reconstruction with a Ram-Lak kernel is used as a reference reconstruction. The results of AIR are compared against the FBP results and against a penalized weighted least squares reconstruction which uses total variation as regularization. The simulations are based on the geometry of the Siemens Somatom Definition Flash scanner. To quantitatively assess image quality, the authors analyze line profiles through resolution patterns to define a contrast

  14. Possible association between phantom vibration syndrome and occupational burnout

    OpenAIRE

    Chen CP; Wu CC; Chang LR; Lin YH

    2014-01-01

    Chao-Pen Chen,1 Chi-Cheng Wu,2 Li-Ren Chang,3 Yu-Hsuan Lin4 1Department of Education, National Taiwan University Hospital, 2Department of Family Medicine, Min-Sheng General Hospital, Taoyuan City, 3Department of Psychiatry, National Taiwan University, College of Medicine, 4Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan Background: Phantom vibration syndrome (PVS) and phantom ringing syndrome (PRS) occur in many cell phone users. Previous studies have indicated an ...

  15. Caracterización de Phantoms por ultrasonidos

    OpenAIRE

    2012-01-01

    El principal objetivo es el desarrollo de sistemas ultrasónicos que permitan medir con precisión distribuciones de los principales parámetros acústicos que caracterizan el comportamiento de los "Tejidos equivalentes" (Phantoms), empleados en laboratorio con el fin de identificar entre tejidos sano y enfermo mediante los ultrasonidos Ortí Anglés, C. (2012). Caracterización de Phantoms por ultrasonidos. http://hdl.handle.net/10251/17787. Archivo delegado

  16. Prevalent hallucinations during medical internships: phantom vibration and ringing syndromes.

    Directory of Open Access Journals (Sweden)

    Yu-Hsuan Lin

    Full Text Available BACKGROUND: Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. METHODS: A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. RESULTS: The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. CONCLUSION: This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships.

  17. Crossing of Phantom Divide in $F(R)$ Gravity

    CERN Document Server

    Bamba, Kazuharu; Nojiri, Shin'ichi; Odintsov, Sergei D

    2010-01-01

    An explicit model of $F(R)$ gravity with realizing a crossing of the phantom divide is reconstructed. In particular, it is shown that the Big Rip singularity may appear in the reconstructed model of $F(R)$ gravity. Such a Big Rip singularity could be avoided by adding $R^2$ term or non-singular viable $F(R)$ theory to the model because phantom behavior becomes transient.

  18. Melatonin membrane receptor (MT1R) expression and nitro-oxidative stress in testis of golden hamster, Mesocricetus auratus: An age-dependent study.

    Science.gov (United States)

    Mukherjee, Arun; Haldar, Chandana

    2015-09-01

    Age-dependent decline in melatonin level induces nitro-oxidative stress that compromises physiological homeostasis including reproduction. However, less information exist regarding the age-dependent variation in local melatonin (lMel) concentration and MT1R expression in testis and its interaction with testicular steroidogenesis and nitro-oxidative stress in golden hamster, Mesocricetus auratus. Therefore, we evaluated lMel level along with MT1R expression and its possible interaction with steroidogenesis and nitro-oxidative stress in testes of young (6weeks), adult (15weeks) and old (2years) aged hamsters. Further, we injected the old hamsters with melatonin to address whether age-related decline in lMel and MT1R is responsible for the reduction in testicular steroidogenesis and antioxidant status. Increased expression of steroidogenic markers suggests increased testicular steroidogenesis in adult hamsters that declined in old hamsters. An age-dependent elevation in the level of NOX, TBARS, corticosterone and the expression of iNOS and GR with a concomitant decrease in enzyme activities for SOD, CAT, GSH-PX indicate increased nitro-oxidative stress in testes. Data suggest that reproductive senescence in male hamsters might be a consequence of declined lMel concentration with MT1R expression inducing nitro-oxidative stress resulting in diminished testicular steroidogenesis. However, administration of Mel in old-aged hamsters significantly increased steroidogenesis and antioxidant status without a significant variation in lMel concentration and MT1R expression in testes. Therefore, decreased lMel and MT1R might not be the causative factor underlying the age-associated decrease in antioxidant defence and steroidogenesis in testes. In conclusion, Mel induced amelioration of testicular oxidative insult and elevation of steroidogenic activity suggests a potential role of increased nitro-oxidative stress underlying the age-dependent decrease in steroidogenesis.

  19. Design and fabrication of a solid simplified head phantom

    Science.gov (United States)

    Tanikawa, Yukari; Imai, Daigo; Mizuno, Sho; Maki, Hiroshi; Shinozaki, Osamu; Yamada, Yukio

    1997-08-01

    Optical tomography aims to image the distribution of optical properties in human bodies by measuring transmitted light at skin surfaces. Pervious calculations and experiments have been mainly performed on phantoms with simple geometries such as slabs and cylinders, but for optical tomography it is inevitable to fully understand light propagation through and perform experiments using phantoms with complicated structures in three dimensions. Therefore, we need stable and realistic solid phantoms for experimental studies toward the goal of optical tomography. In this study, we have fabricated two types of solid phantoms which optically and anatomically simulate human heads. One has a shape and structures of a part of human head above eye plane, and the other has a more simplified shape of hemisphere. These phantoms consisted of five layers which corresponded to five tissue types in human head; i.e., skin, skull, clear CSF layer, gray matter and white matter. Size and optical properties were given according to those of human neonatal head. After taking original shapes from MRI images, prototypes of five layers were fabricated by a rapid prototyping based photolithography. Epoxy resin with titanium oxide particles as scatterers and green dye as absorber was cast into the molds of the prototypes to make optical phantoms. Absorbers simulating inhomogeneities were also embedded.

  20. Use of optical skin phantoms for calibration of dermatological lasers

    Science.gov (United States)

    Wróbel, M. S.; Sekowska, A.; Marchwiński, M.; Galla, S.; Cenian, A.

    2016-09-01

    A wide range of dermatological diseases can be efficiently treated using laser heating. Nevertheless, before the new laser is introduced into clinical practice, its parameters and ability to interact with human skin have to be carefully examined. In order to do that optical skin phantoms can be used. Such phantoms closely imitate the scattering and absorption properties of real human skin tissue along with its thermal properties, such as capacitance and conductivity specific heat. We have fabricated a range of optical tissue phantoms based on polyvinylchloride-plastisol PVC-P with varying optical properties, including the absorption, scattering and density of the matrix material. We have utilized a pre-clinical dermatological laser system with a 975 nm diode laser module. A range of laser settings were tested, such as laser pulse duration, laser power and number of pulses. We have studied laser irradiation efficiency on fabricated optical tissue phantoms. Measurements of the temporal and spatial temperature distribution on the phantoms' surface were performed using thermographic imaging. The comparison of results between tissues' and phantoms' optical and thermal response prove that they can be used for approximate evaluation of laser heating efficiency. This study presents a viable approach for calibration of dermatological lasers which can be utilized in practice.

  1. Phantom Energy Accretion by a Stringy Charged Black Hole

    Institute of Scientific and Technical Information of China (English)

    M.Sharif; G.Abbas

    2012-01-01

    We investigate the dynamical behavior of phantom energy near a stringy magnetically charged black hole. For this purpose, we derive equations of motion for steady-state spherically symmetric Row of phantom energy onto the stringy magnetically charged black hole. It is found that phantom energy accreting onto a black hole decreases its mass. Further, the location of the critical points of accretion is explored, which yields a mass to charge ratio. This ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity, hence cosmic censorship hypothesis remains valid here.%We investigate the dynamical behavior of phantom energy near a stringy magnetically charged black hole.For this purpose,we derive equations of motion for steady-state spherically symmetric flow of phantom energy onto the stringy magnetically charged black hole.It is found that phantom energy accreting onto a black hole decreases its mass.Further,the location of the critical points of accretion is explored,which yields a mass to charge ratio.This ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity,hence cosmic censorship hypothesis remains valid here.

  2. 3D dosimetry estimation for selective internal radiation therapy (SIRT) using SPECT/CT images: a phantom study

    Science.gov (United States)

    Debebe, Senait A.; Franquiz, Juan; McGoron, Anthony J.

    2015-03-01

    Selective Internal Radiation Therapy (SIRT) is a common way to treat liver cancer that cannot be treated surgically. SIRT involves administration of Yttrium - 90 (90Y) microspheres via the hepatic artery after a diagnostic procedure using 99mTechnetium (Tc)-macroaggregated albumin (MAA) to detect extrahepatic shunting to the lung or the gastrointestinal tract. Accurate quantification of radionuclide administered to patients and radiation dose absorbed by different organs is of importance in SIRT. Accurate dosimetry for SIRT allows optimization of dose delivery to the target tumor and may allow for the ability to assess the efficacy of the treatment. In this study, we proposed a method that can efficiently estimate radiation absorbed dose from 90Y bremsstrahlung SPECT/CT images of liver and the surrounding organs. Bremsstrahlung radiation from 90Y was simulated using the Compton window of 99mTc (78keV at 57%). 99mTc images acquired at the photopeak energy window were used as a standard to examine the accuracy of dosimetry prediction by the simulated bremsstrahlung images. A Liqui-Phil abdominal phantom with liver, stomach and two tumor inserts was imaged using a Philips SPECT/CT scanner. The Dose Point Kernel convolution method was used to find the radiation absorbed dose at a voxel level for a three dimensional dose distribution. This method will allow for a complete estimate of the distribution of radiation absorbed dose by tumors, liver, stomach and other surrounding organs at the voxel level. The method provides a quantitative predictive method for SIRT treatment outcome and administered dose response for patients who undergo the treatment.

  3. Evidence for novel age-dependent network structures as a putative primo vascular network in the dura mater of the rat brain

    Institute of Scientific and Technical Information of China (English)

    Ho-Sung Lee; Dai-In Kang; Seung Zhoo Yoon; Yeon Hee Ryu; Inhyung Lee; Hoon-Gi Kim; Byung-Cheon Lee; Ki Bog Lee

    2015-01-01

    With chromium-hematoxylin staining, we found evidence for the existence of novel age-depen-dent network structures in the dura mater of rat brains. Under stereomicroscopy, we noticed that chromium-hematoxylin-stained threadlike structures, which were barely observable in 1-week-old rats, were networked in specific areas of the brain, for example, the lateral lobes and the cerebella, in 4-week-old rats. In 7-week-old rats, those structures were found to have become larger and better networked. With phase contrast microscopy, we found that in 1-week-old rats, chromium-hematoxylin-stained granules were scattered in the same areas of the brain in which the network structures would later be observed in the 4- and 7-week-old rats. Such age-depen-dent network structures were examined by using optical and transmission electron microscopy, and the following results were obtained. The scattered granules fused into networks with increas-ing age. Cross-sections of the age-dependent network structures demonstrated heavily-stained basophilic substructures. Transmission electron microscopy revealed the basophilic substructures to be clusters with high electron densities consisting of nanosized particles. We report these data as evidence for the existence of age-dependent network structures in the dura mater, we discuss their putative functions of age-dependent network structures beyond the general concept of the dura mater as a supporting matrix.

  4. Variability of average SUV from several hottest voxels is lower than that of SUVmax and SUVpeak

    Energy Technology Data Exchange (ETDEWEB)

    Laffon, E. [CHU de Bordeaux, Service de Medecine Nucleaire, Hopital du Haut-Leveque, Pessac (France); Universite de Bordeaux 2, Centre de Recherche Cardio-Thoracique, Bordeaux (France); INSERM U 1045, Centre de Recherche Cardio-Thoracique, Bordeaux (France); Lamare, F.; Clermont, H. de [CHU de Bordeaux, Service de Medecine Nucleaire, Hopital du Haut-Leveque, Pessac (France); Burger, I.A. [University Hospital of Zurich, Division of Nuclear Medicine, Department Medical Radiology, Zurich (Switzerland); Marthan, R. [Universite de Bordeaux 2, Centre de Recherche Cardio-Thoracique, Bordeaux (France); INSERM U 1045, Centre de Recherche Cardio-Thoracique, Bordeaux (France)

    2014-08-15

    To assess variability of the average standard uptake value (SUV) computed by varying the number of hottest voxels within an {sup 18}F-fluorodeoxyglucose ({sup 18}F-FDG)-positive lesion. This SUV metric was compared with the maximal SUV (SUV{sub max}: the hottest voxel) and peak SUV (SUV{sub peak}: SUV{sub max} and its 26 neighbouring voxels). Twelve lung cancer patients (20 lesions) were analysed using PET dynamic acquisition involving ten successive 2.5-min frames. In each frame and lesion, average SUV obtained from the N = 5, 10, 15, 20, 25 or 30 hottest voxels (SUV{sub max-N}){sub ,} SUV{sub max} and SUV{sub peak} were assessed. The relative standard deviations (SDrs) from ten frames were calculated for each SUV metric and lesion, yielding the mean relative SD from 20 lesions for each SUV metric (SDr{sub N}, SDr{sub max} and SDr{sub peak}), and hence relative measurement error and repeatability (MEr-R). For each N, SDr{sub N} was significantly lower than SDr{sub max} and SDr{sub peak}. SDr{sub N} correlated strongly with N: 6.471 x N{sup -0.103} (r = 0.994; P < 0.01). MEr-R of SUV{sub max-30} was 8.94-12.63 % (95 % CL), versus 13.86-19.59 % and 13.41-18.95 % for SUV{sub max} and SUV{sub peak} respectively. Variability of SUV{sub max-N} is significantly lower than for SUV{sub max} and SUV{sub peak}. Further prospective studies should be performed to determine the optimal total hottest volume, as voxel volume may depend on the PET system. (orig.)

  5. Quantitative myocardial perfusion PET parametric imaging at the voxel-level.

    Science.gov (United States)

    Mohy-Ud-Din, Hassan; Lodge, Martin A; Rahmim, Arman

    2015-08-01

    Quantitative myocardial perfusion (MP) PET has the potential to enhance detection of early stages of atherosclerosis or microvascular dysfunction, characterization of flow-limiting effects of coronary artery disease (CAD), and identification of balanced reduction of flow due to multivessel stenosis. We aim to enable quantitative MP-PET at the individual voxel level, which has the potential to allow enhanced visualization and quantification of myocardial blood flow (MBF) and flow reserve (MFR) as computed from uptake parametric images. This framework is especially challenging for the (82)Rb radiotracer. The short half-life enables fast serial imaging and high patient throughput; yet, the acquired dynamic PET images suffer from high noise-levels introducing large variability in uptake parametric images and, therefore, in the estimates of MBF and MFR. Robust estimation requires substantial post-smoothing of noisy data, degrading valuable functional information of physiological and pathological importance. We present a feasible and robust approach to generate parametric images at the voxel-level that substantially reduces noise without significant loss of spatial resolution. The proposed methodology, denoted physiological clustering, makes use of the functional similarity of voxels to penalize deviation of voxel kinetics from physiological partners. The results were validated using extensive simulations (with transmural and non-transmural perfusion defects) and clinical studies. Compared to post-smoothing, physiological clustering depicted enhanced quantitative noise versus bias performance as well as superior recovery of perfusion defects (as quantified by CNR) with minimal increase in bias. Overall, parametric images obtained from the proposed methodology were robust in the presence of high-noise levels as manifested in the voxel time-activity-curves.

  6. The accuracy and reliability of CBCT measurements using a custom phantom

    Energy Technology Data Exchange (ETDEWEB)

    Palomo, J.M.; Christopher, M.; Hans, M.G. [Case Western Reserve Univ. School of Dental Medicine, Dept. of Orthodontics, Cleveland, OH (United States)

    2007-06-15

    Cone beam computerized tomography (CBCT) is receiving increased attention within Dentistry. Objectives: To compare linear measurements taken from CBCT and cephalometric images to physical measurements of a three-dimensional (3D) phantom. A customized plastic pyramid with embedded 0.8 mm diameter metallic markers placed 6.5 mm apart in width, height and length was used. The distances between the markers were measured with a digital caliper. CBCT scans were taken at 3 different field of views (FOV), 120 kVp, and mA settings of 2 and 15 mA, yielding 12 total scans. The FOV's used were 6', 9' and 12', with voxel sizes of 0.18, 0.28, and 0.38 mm, respectively. Lateral and frontal cephalograms of the phantom were taken and measured with a digital caliper. The CBCT images were measured using commercially available software (CyberMed's Accurex v.1.1). All measurements were repeated three times by the same operator and average was used for analysis. MS Excel 2003 was used to calculate mathematical differences and SPSS 14 for correlations and paired t-tests. Intraoperator analysis for CBCT and Cephalometric measurements showed good correlation (r > 0.75). No statistically significant differences were found between CBCT images taken at 2 mA and 15 mA (P = 0.6. r = 0.85). Compared to direct measures, CBCT measures were smaller with an average difference of 0.16 mm {+-} 0.12 for 6' FOV, 0.17 mm {+-} 016 for 9' FOV, and 0.20 mm {+-} 0.19 for 12' FOV. All CBCT measurements were slightly more accurate near the center of the image, with the width showing the greatest difference (0.23 mm {+-} 0.07), but with no statistically significant difference found between the center and the extremes. Cephalometric measurements, even after adjusting for enlargement, were 0.32 mm {+-} 0.11 larger than direct measures. CBCT measurements taken at the settings tested were comparable in accuracy to cephalometric radiographs and were slightly smaller than

  7. Energy Efficient Resource Allocation for Phantom Cellular Networks

    KAUST Repository

    Abdelhady, Amr

    2016-04-01

    Multi-tier heterogeneous networks have become an essential constituent for next generation cellular networks. Meanwhile, energy efficiency (EE) has been considered a critical design criterion along with the traditional spectral efficiency (SE) metric. In this context, we study power and spectrum allocation for the recently proposed two-tier network architecture known as phantom cellular networks. The optimization framework includes both EE and SE. First, we consider sparsely deployed cells experiencing negligible interference and assume perfect channel state information (CSI). For this setting, we propose an algorithm that finds the SE and EE resource allocation strategies. Then, we compare the performance of both design strategies versus number of users, and phantom cells share of the total available resource units (RUs). We aim to investigate the effect of some system parameters to achieve improved SE performance at a non-significant loss in EE performance, or vice versa. It is found that increasing phantom cells share of RUs decreases the SE performance loss due to EE optimization when compared with the optimized SE performance. Second, we consider the densely deployed phantom cellular networks and model the EE optimization problem having into consideration the inevitable interference and imperfect channel estimation. To this end, we propose three resource allocation strategies aiming at optimizing the EE performance metric of this network. Furthermore, we investigate the effect of changing some of the system parameters on the performance of the proposed strategies, such as phantom cells share of RUs, number of deployed phantom cells within a macro cell coverage, number of pilots and the maximum power available for transmission by the phantom cells BSs. It is found that increasing the number of pilots deteriorates the EE performance of the whole setup, while increasing maximum power available for phantom cells transmissions reduces the EE of the whole setup in a

  8. Accuracy in the diagnosis of vertical root fractures, external root resorptions, and root perforations using cone-beam computed tomography with different voxel sizes of acquisition

    Directory of Open Access Journals (Sweden)

    Fernanda Paula Bragatto

    2016-01-01

    Conclusions: Voxel size 0.125 mm produced images with the best resolution without increasing radiation levels to the patient when compared to voxel sizes 0.200 and 0.250 mm. Voxel sizes 0.300 and 0.400 mm should be avoided in the identification of root alterations.

  9. Skin Dosimetry in Breast Teletherapy on a Phantom Anthropomorphic and Anthropometric Phantom

    Energy Technology Data Exchange (ETDEWEB)

    Batista Nogueira, Luciana [Anatomy and Imaging Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Lemos Silva, Hugo Leonardo [Santa Casa Hospital, Belo Horizonte (Brazil); Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil)

    2015-07-01

    This paper addresses the breast teletherapy dosimetry. The goal is to evaluate and compare absorbed doses in equivalent skin tissue, TE-skin, of an anthropomorphic and anthropometric breast phantom submitted to breast radiotherapy. The methodology involved the reproduction of a set of tomographic images of the phantom; the elaboration of conformational radiotherapy planning in the SOMAVISION and CadPlan (TPS) software; and the synthetic breast irradiation by parallel opposed fields in 3D conformal teletherapy at 6 MV linear accelerator Clinac-2100 C from VARIAN with prescribed dose (PD) of 180 cGy to the target volume (PTV), referent to the glandular tissue. Radiochromic films EBT2 were selected as dosimeters. Two independent calibration processes of films with solid water Gammex 457 plates and water filled box were produced. Curves of optical density (OD) versus absorbed dose were produced. Dosimeters were positioned in the external region of the breast phantom in contact with TE-skin, area of 4.0 cm{sup 2} each. The irradiation process was prepared in duplicate to check the reproducibility of the technique. The radiochromic films were scanned and their response in RGB (Red, Green, Blue) analyzed by the ImageJ software. The optical density was obtained and converted to dose based on the calibration curves. Thus, the spatial dose distribution in the skin was reproduced. The absorbed doses measured on the radiochromic films in TE-skin showed values between upper and lower quadrants at 9 o'clock in the range of 54% of PD, between the upper and lower quadrants 3 o'clock in the range of 72% and 6 o'clock at the lower quadrant in the range of 68 % of PD. The values are ±64% (p <0.05) according to the TPS. It is concluded that the depth dose measured in solid water plates or water box reproduce equivalent dose values for both calibration processes of the radiochromic films. It was observed that the skin received doses ranging from 50% to 78% of the

  10. The visual phantom illusion: A perceptual product of surface completion depending on brightness and contrast.

    Science.gov (United States)

    Kitaoka, Akiyoshi; Gyoba, Jiro; Sakurai, Kenzo

    2006-01-01

    The visual phantom illusion was first discovered by Rosenbach in 1902 and named 'moving phantoms' by Tynan and Sekuler in 1975 because of its strong dependence on motion. It was later revealed that phantoms can be generated by flickering the grating (flickering phantoms) or by low-luminance stationary gratings under dark adaptation (stationary phantoms). Although phantoms are much more visible at scotopic or mesopic adaptation levels (scotopic phantoms) than at photopic levels, we proposed a new phantom illusion which is fully visible in photopic vision (photopic phantoms). In 2001, we revealed that the visual phantom illusion is a higher-order perceptual construct or a Gestalt, which depends on the mechanism of perceptual transparency. Perceptual transparency is known as a perceptual product based upon brightness and contrast. We furthermore manifested the shared mechanisms between visual phantoms and neon color spreading or between visual phantoms and the Petter effect. In our recent study, the visual phantom illusion can also be seen with a stimulus of contrast-modulated gratings. We assume that this effect also depends on perceptual transparency induced by contrast modulation. Moreover, we found that the Craik-O'Brien-Cornsweet effect and other brightness illusions can generate the visual phantom illusion. In any case, we explain the visual phantom illusion in terms of surface completion, which is given by perceptual transparency.

  11. CREATION OF FEMALE COMPUTATIONAL PHANTOMS FOR CALIBRATION OF LUNG COUNTERS.

    Science.gov (United States)

    Lombardo, Pasquale Alessandro; Lebacq, Anne Laure; Vanhavere, Filip

    2016-09-01

    Plutonium isotopes are of high concern because they lead to high doses. In case of contamination, the activity burden inside the lungs should be assessed accurately. Many studies showed that the presence of breasts has a substantial influence on lung counting efficiencies. Currently, the calibration of most lung counting systems is done by means of physical phantoms representing only male chests. A set of female computational phantoms has been developed in order to provide gender-specific efficiency calibrations for the (241)Am gamma emission (59.54 keV). The phantoms were created starting from a library of female chest phantoms provided by Institut de radioprotection et de sûreté nucléaire (IRSN) (Farah, J. Amélioration des mesures anthroporadiamétriques personnalisées assistées par calcul Monte Carlo: optimisation des temps de calculs et méthodologie de mesure pour l'établissement de la répartition d'activite. PhD Thesis, 2011). While the IRSN phantoms represent a supine measurement position, the SCK•CEN lung counter set-up requires the persons to be sitting in a chair. Using open-source software, the breast shapes of the original phantoms have been recreated to simulate the drooping of breasts in vertical sitting position. A Monte Carlo approach was chosen for calculating calibration coefficients for female lung counting. The results obtained with MCNPx 2.7 simulations showed a significant decrease in the detection efficiency. For bigger bust and breast sizes, the detection efficiency showed to be up to 10 times lower than the ones measured with the Livermore male torso phantom.

  12. WE-D-303-00: Computational Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, John [Duke University Medical Center, Durham, NC (United States); Brigham and Women’s Hospital and Dana-Farber Cancer Institute, Boston, MA (United States)

    2015-06-15

    Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems.

  13. Building Point Detection from Vehicle-Borne LiDAR Data Based on Voxel Group and Horizontal Hollow Analysis

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-05-01

    Full Text Available Information extraction and three-dimensional (3D reconstruction of buildings using the vehicle-borne laser scanning (VLS system is significant for many applications. Extracting LiDAR points, from VLS, belonging to various types of building in large-scale complex urban environments still retains some problems. In this paper, a new technical framework for automatic and efficient building point extraction is proposed, including three main steps: (1 voxel group-based shape recognition; (2 category-oriented merging; and (3 building point identification by horizontal hollow ratio analysis. This article proposes a concept of “voxel group” based on the voxelization of VLS points: each voxel group is composed of several voxels that belong to one single real-world object. Then the shapes of point clouds in each voxel group are recognized and this shape information is utilized to merge voxel group. This article puts forward a characteristic nature of vehicle-borne LiDAR building points, called “horizontal hollow ratio”, for efficient extraction. Experiments are analyzed from two aspects: (1 building-based evaluation for overall experimental area; and (2 point-based evaluation for individual building using the completeness and correctness. The experimental results indicate that the proposed framework is effective for the extraction of LiDAR points belonging to various types of buildings in large-scale complex urban environments.

  14. Prediction of fMRI time series of a single voxel using radial basis function neural network

    Science.gov (United States)

    Song, Sutao; Zhang, Jiacai; Yao, Li

    2011-03-01

    A great deal of current literature regarding functional neuroimaging has elucidated the relationships of neurons distributed all over the brain. Modern neuroimaging techniques, such as the functional MRI (fMRI), provide a convenient tool for people to study the correlation among different voxels as well as the spatio-temporal patterns of brain activity. In this study, we present a computational model using radial basis function neural network (RBF-NN) to predict the fMRI voxel activation with the activation of other voxels acquired at the same time. The fMRI data from a visual images stimuli presentation experiment was separated into two sets; one was used to train the model, and the other to validate the accuracy or generalizability of the model. In the visual stimuli presentation experiment, the subject did simple one-back-repetition tasks when four categories of stimuli (houses, faces, cars, and cats) were presented. Voxel sets A and B were selected from fMRI data by two different voxel selection criterion: (1) Voxel set A are those activated for any kind of object stronger than the other three objects in regions of interest (ROIs) without correction (P=0.001); (2) Voxel set B are those activated for at least one of the categories of stimuli within the ROIs (FWE correction, P=0.05). RBF-NN regression models construct the nonlinear relationship between the activation of voxels in A and B. Our test results showed that RBF-NN can capture the nonlinear relationship existing in neurons and reveal the relationship between voxel's activation from different brain regions.

  15. Neutron dosimetry in organs of an adult human phantom using linacs with multileaf collimator in radiotherapy treatments

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Ovalle, S. A.; Barquero, R.; Gomez-Ros, J. M.; Lallena, A. M. [Grupo de Fisica Nuclear Aplicada y Simulacion, Universidad Pedagogica y Tecnologica de Colombia, Tunja 15001000 (Colombia); Servicio de Proteccion Radiologica, Hospital Clinico Universitario, E-47012 Valladolid (Spain) and Departamento de Radiologia, Universidad de Valladolid, Valladolid E-47071 (Spain); CIEMAT, Avda. Complutense 40, Madrid, E-28040 (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, Granada E-18071 (Spain)

    2012-05-15

    AP, and breasts and red marrow, in RLAT. Equivalent and effective doses obtained for MAX06/FAX06 were smaller (between 2 and 20 times) than those quoted for the mathematical phantoms ADAM/EVA in ICRP-74. Conclusions: The new calculations of conversion coefficients for neutron irradiation in AP and RLAT irradiation geometries show a reduction in the values of effective dose by factors 7 (AP) and 6 (RLAT) with respect to the old data obtained with mathematical phantoms. The existence of tissues or anatomical regions with maximum absorbed doses, such as penis, lens of eyes, fascia (part of connective tissue), etc., organs/tissues that classic mathematical phantoms did not include because they were not considered for the study of stochastic effects, has been revealed. Absorbed doses due to photons, obtained following the same simulation methodology, are larger than those due to neutrons, reaching values 100 times larger as the primary beam is approached. However, for organs far from the treated volume, absorbed photon doses can be up to three times smaller than neutron ones. Calculations using voxel phantoms permitted to know the organ dose conversion coefficients per MU due to secondary neutrons in the complete anatomy of a patient.

  16. Development of VOXEL-MAN Three-Dimensional Navigator of Acupuncture%基于VOXEL-MAN针灸学三维影像浏览器的研究

    Institute of Scientific and Technical Information of China (English)

    邵水金; 牟芳芳; 严振国; 刘红菊; 白娟; 庄天戈; 赵静; 秦翊麟

    2005-01-01

    以腧穴解剖研究成果为基础,将临床常用的18个危险穴位的解剖结构数据融入汉堡大学VOXEL-MAN三维数字化虚拟人体中,开发一套VOXEL-MAN 3D Navigator:Acupuncture运行软件(针灸学三维影像浏览器),动态、三维显示腧穴的层次解剖结构和不同角度针刺所经过的断面解剖结构,并建立相关的知识库体系,能够加深对图像内容的理解,有利于提高临床针刺疗效和避免针刺意外事故的发生,并为针灸提供一种理想直观的多媒体教学手段和方法.

  17. Capturing the Perceived Phantom Limb through Virtual Reality

    Directory of Open Access Journals (Sweden)

    Christian Rogers

    2016-01-01

    Full Text Available Phantom limb is the sensation amputees may feel when the missing limb is still attached to the body and is still moving as it would if it still existed. Despite there being between 50 and 80% of amputees who report neuropathic pain, also known as phantom limb pain (PLP, there is still little understanding of why PLP occurs. There are no fully effective long-term treatments available. One of the struggles with PLP is the difficulty for amputees to describe the sensations of their phantom limbs. The sensations may be of a limb that is in a position that is impossible for a normal limb to attain. The goal of this project was to treat those with PLP by developing a system to communicate the sensations those with PLP were experiencing accurately and easily through various hand positions using a model arm with a user friendly interface. The system was developed with Maya 3D animation software, the Leap Motion input device, and the Unity game engine. The 3D modeled arm was designed to mimic the phantom sensation being able to go beyond normal joint extensions of regular arms. The purpose in doing so was to obtain a true 3D visualization of the phantom limb.

  18. Radiological equipment analyzed by specific developed phantoms and software

    Energy Technology Data Exchange (ETDEWEB)

    Soto, M.; Campayo, J. M. [Logistica y Acondicionamientos Industriales SAU, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Mayo, P. [TITANIA Servicios Tecnologicos SL, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Verdu, G.; Rodenas, F., E-mail: m.soto@lainsa.co [ISIRYIM Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia (Spain)

    2010-10-15

    The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

  19. Evaluation of SPECT imaging using myocardial phantoms in Akita prefecture

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Kiyohiko [Akita Univ. (Japan). Hospital; Watarai, Jiro; Miura, Mamoru

    1998-09-01

    Evaluation of SPECT imaging using myocardial phantom in Akita Prefecture. The Society of Nuclear Medicine for Circulation disease in Akita was established in July, 1997. To improve myocardial spect imaging in Akita Prefecture, we first visually evaluated two acrlic defect (2 cm{phi} x 1 cm thickness aqcliel and 1 cm{phi} x 1 cm thickness) images of long axis and short axis of myocardial phantoms, using 14 SPECT Cameras. These defect images of myocardial phantom were evaluated by four cardiologists and twelve radiologists between August and December, 1996. Secondly, we measured the FWHM of four line sources (anterior, lateral, inferior, and septum positions in the short axis of myocardial phantom) using quantitative analysis by myocardial phantom between April and July, 1997. The results were reported at the 4th and 5th meeting of the Society of Nuclear Medicine for Circulation Disease in Akita. In conclusion, about 70% of myocardial spect images were of good or normal quality, whereas about 30% of the images were evaluated as of bad quality. To improve the myocardial spect images, we recognized that the basic performance of the SPECT cameras need be investigated. (author)

  20. OSL Based Anthropomorphic Phantom and Real-Time Organ Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    David E. Hintenlang, Ph.D

    2009-02-10

    The overall objective of this project was the development of a dosimetry system that provides the direct measurement of organ does in real-time with a sensitivity that makes it an effective tool for applications in a wide variety of health physics applications. The system included the development of a real-time readout system for fiber optic coupled (FOC) dosimeters that is integrated with a state-of-art anthropomorphic phantom to provide instantaneous measures of organ doses throughout the phantom. The small size of the FOC detectors and optical fibers allow the sensitive volume of the detector to be located at organ centroids (or multiple locations distributed through the organ) within a tissue equivalent, anthropomorphic phantom without perturbing the tissue equivalent features of the phantom. The developed phantom/dosimetry system can be used in any environment where personnel may be exposed to gamma or x-ray radiations to provide the most accurate determinations of organ and effective doses possible to date.

  1. Micromechanical analysis of nanocomposites using 3D voxel based material model

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon

    2012-01-01

    A computational study on the effect of nanocomposite structures on the elastic properties is carried out with the use of the 3D voxel based model of materials and the combined Voigt–Reuss method. A hierarchical voxel based model of a material reinforced by an array of exfoliated and intercalated...... nanoclay platelets surrounded by interphase layers is developed. With this model, the elastic properties of the interphase layer are estimated using the inverse analysis. The effects of aspect ratio, intercalation and orientation of nanoparticles on the elastic properties of the nanocomposites are analyzed....... For modeling the damage in nanocomposites with intercalated structures, “four phase” model is suggested, in which the strength of “intrastack interphase” is lower than that of “outer” interphase around the nanoplatelets. Analyzing the effect of nanoreinforcement in the matrix on the failure probability...

  2. Whole-brain voxel-based morphometry of white matter in medial temporal lobe epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Yu Aihong [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, Beijing 100053 (China); Li Kuncheng [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, Beijing 100053 (China)], E-mail: Likuncheng@vip.sina.com; Li Lin; Shan Baoci [Institute of High Energy Physics, Chinese Academy of Sciences (China); Wang Yuping; Xue Sufang [Department of Neurology, Xuanwu Hospital, Capital University of Medical Sciences (China)

    2008-01-15

    Purpose: The purpose of this study was to analyze whole-brain white matter changes in medial temporal lobe epilepsy (MTLE). Materials and methods: We studied 23 patients with MTLE and 13 age- and sex-matched healthy control subjects using voxel-based morphometry (VBM) on T1-weighted 3D datasets. The seizure focus was right sided in 11 patients and left sided in 12. The data were collected on a 1.5 T MR system and analyzed by SPM 99 to generate white matter density maps. Results: Voxel-based morphometry revealed diffusively reduced white matter in MTLE prominently including bilateral frontal lobes, bilateral temporal lobes and corpus callosum. White matter reduction was also found in the bilateral cerebellar hemispheres in the left MTLE group. Conclusion: VBM is a simple and automated approach that is able to identify diffuse whole-brain white matter reduction in MTLE.

  3. Linguistic Summarization of Video for Fall Detection Using Voxel Person and Fuzzy Logic.

    Science.gov (United States)

    Anderson, Derek; Luke, Robert H; Keller, James M; Skubic, Marjorie; Rantz, Marilyn; Aud, Myra

    2009-01-01

    In this paper, we present a method for recognizing human activity from linguistic summarizations of temporal fuzzy inference curves representing the states of a three-dimensional object called voxel person. A hierarchy of fuzzy logic is used, where the output from each level is summarized and fed into the next level. We present a two level model for fall detection. The first level infers the states of the person at each image. The second level operates on linguistic summarizations of voxel person's states and inference regarding activity is performed. The rules used for fall detection were designed under the supervision of nurses to ensure that they reflect the manner in which elders perform these activities. The proposed framework is extremely flexible. Rules can be modified, added, or removed, allowing for per-resident customization based on knowledge about their cognitive and physical ability.

  4. Age-dependent alterations of the hippocampal cell composition and proliferative potential in the hAβPPSwInd-J20 mouse.

    Science.gov (United States)

    Fu, YuHong; Rusznák, Zoltán; Kwok, John B J; Kim, Woojin Scott; Paxinos, George

    2014-01-01

    The J20 mouse expresses human mutant amyloid-β protein precursor (hAβPPSwInd) and is an established transgenic model of Alzheimer's disease (AD). From the age of 5 months, amyloid-β (Aβ) deposits appear in the hippocampus with concomitant increase of AD-associated features. Although changes occurring after the appearance of Aβ deposits have been extensively studied, very little is known about alterations that occur prior to 5 months. The present study aimed to identify changes in the cellular composition and proliferative potential of the J20 hippocampus using 1-18-month-old mice. Neuronal, non-neuronal, Ki-67+, and TUNEL+ cell numbers were counted with the isotropic fractionator method. Age-dependent changes of the expression of microglia-, astrocyte-, and neurogenesis-specific markers were sought in the entire hippocampus. Several transgene-associated changes were revealed before the appearance of Aβ deposits. The number of proliferating cells decreased whereas the number of microglia clusters increased as early as 4 weeks of age. The neurogenesis was also impaired in the dentate gyrus of 7-11-week-old J20 mice. A statistically significant negative correlation was found between the number of proliferating cells and age in both populations, but the time course of the age-dependence was steeper in wild-type than in J20 mice. Negative age-dependence was noted when the number of cells committed to apoptosis was examined. Our results indicate that overexpression of mutant hAβPP initiates a cascade of pathologic events well before the appearance of visible Aβ plaques. Accordingly, early signs of AD include reduced cell proliferation, impaired neurogenesis, and increased activity of microglia in the hippocampus.

  5. Voxel-wise grey matter asymmetry analysis in left- and right-handers.

    Science.gov (United States)

    Ocklenburg, Sebastian; Friedrich, Patrick; Güntürkün, Onur; Genç, Erhan

    2016-10-28

    Handedness is thought to originate in the brain, but identifying its structural correlates in the cortex has yielded surprisingly incoherent results. One idea proclaimed by several authors is that structural grey matter asymmetries might underlie handedness. While some authors have found significant associations with handedness in different brain areas (e.g. in the central sulcus and precentral sulcus), others have failed to identify such associations. One method used by many researchers to determine structural grey matter asymmetries is voxel based morphometry (VBM). However, it has recently been suggested that the standard VBM protocol might not be ideal to assess structural grey matter asymmetries, as it establishes accurate voxel-wise correspondence across individuals but not across both hemispheres. This could potentially lead to biased and incoherent results. Recently, a new toolbox specifically geared at assessing structural asymmetries and involving accurate voxel-wise correspondence across hemispheres has been published [F. Kurth, C. Gaser, E. Luders. A 12-step user guide for analyzing voxel-wise gray matter asymmetries in statistical parametric mapping (SPM), Nat Protoc 10 (2015), 293-304]. Here, we used this new toolbox to re-assess grey matter asymmetry differences in left- vs. right-handers and linked them to quantitative measures of hand preference and hand skill. While we identified several significant left-right asymmetries in the overall sample, no difference between left- and right-handers reached significance after correction for multiple comparisons. These findings indicate that the structural brain correlates of handedness are unlikely to be rooted in macroscopic grey matter area differences that can be assessed with VBM. Future studies should focus on other potential structural correlates of handedness, e.g. structural white matter asymmetries.

  6. Voxel3D “搭积木”的建模软件

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    要介绍Voxel3D,先得作个名词解释:Voxel是Volume Element 这两个词的缩写,我们把Voxel叫做“体元”,它就相当于二维图像中的“像素”,是三维空间中的基本小方块。

  7. A voxel-wise encoding model for early visual areas decodes mental images of remembered scenes.

    Science.gov (United States)

    Naselaris, Thomas; Olman, Cheryl A; Stansbury, Dustin E; Ugurbil, Kamil; Gallant, Jack L

    2015-01-15

    Recent multi-voxel pattern classification (MVPC) studies have shown that in early visual cortex patterns of brain activity generated during mental imagery are similar to patterns of activity generated during perception. This finding implies that low-level visual features (e.g., space, spatial frequency, and orientation) are encoded during mental imagery. However, the specific hypothesis that low-level visual features are encoded during mental imagery is difficult to directly test using MVPC. The difficulty is especially acute when considering the representation of complex, multi-object scenes that can evoke multiple sources of variation that are distinct from low-level visual features. Therefore, we used a voxel-wise modeling and decoding approach to directly test the hypothesis that low-level visual features are encoded in activity generated during mental imagery of complex scenes. Using fMRI measurements of cortical activity evoked by viewing photographs, we constructed voxel-wise encoding models of tuning to low-level visual features. We also measured activity as subjects imagined previously memorized works of art. We then used the encoding models to determine if putative low-level visual features encoded in this activity could pick out the imagined artwork from among thousands of other randomly selected images. We show that mental images can be accurately identified in this way; moreover, mental image identification accuracy depends upon the degree of tuning to low-level visual features in the voxels selected for decoding. These results directly confirm the hypothesis that low-level visual features are encoded during mental imagery of complex scenes. Our work also points to novel forms of brain-machine interaction: we provide a proof-of-concept demonstration of an internet image search guided by mental imagery.

  8. A method based on Monte Carlo simulations and voxelized anatomical atlases to evaluate and correct uncertainties on radiotracer accumulation quantitation in beta microprobe studies in the rat brain

    Science.gov (United States)

    Pain, F.; Dhenain, M.; Gurden, H.; Routier, A. L.; Lefebvre, F.; Mastrippolito, R.; Lanièce, P.

    2008-10-01

    The β-microprobe is a simple and versatile technique complementary to small animal positron emission tomography (PET). It relies on local measurements of the concentration of positron-labeled molecules. So far, it has been successfully used in anesthetized rats for pharmacokinetics experiments and for the study of brain energetic metabolism. However, the ability of the technique to provide accurate quantitative measurements using 18F, 11C and 15O tracers is likely to suffer from the contribution of 511 keV gamma rays background to the signal and from the contribution of positrons from brain loci surrounding the locus of interest. The aim of the present paper is to provide a method of evaluating several parameters, which are supposed to affect the quantification of recordings performed in vivo with this methodology. We have developed realistic voxelized phantoms of the rat whole body and brain, and used them as input geometries for Monte Carlo simulations of previous β-microprobe reports. In the context of realistic experiments (binding of 11C-Raclopride to D2 dopaminergic receptors in the striatum; local glucose metabolic rate measurement with 18F-FDG and H2O15 blood flow measurements in the somatosensory cortex), we have calculated the detection efficiencies and corresponding contribution of 511 keV gammas from peripheral organs accumulation. We confirmed that the 511 keV gammas background does not impair quantification. To evaluate the contribution of positrons from adjacent structures, we have developed β-Assistant, a program based on a rat brain voxelized atlas and matrices of local detection efficiencies calculated by Monte Carlo simulations for several probe geometries. This program was used to calculate the 'apparent sensitivity' of the probe for each brain structure included in the detection volume. For a given localization of a probe within the brain, this allows us to quantify the different sources of beta signal. Finally, since stereotaxic accuracy is

  9. A Voxel-based Method for Forest Change Detection after Fire Using LiDAR Data

    Science.gov (United States)

    Xu, Z.

    2015-12-01

    A Voxel-based Method for Forest Change Detection after Fire Using LiDAR DataZewei Xu and Jonathan A. Greenberg Traditional methods of forest fire modeling focus on the patterns of burning in two-dimensions at relatively coarse resolutions. However, fires spread in complex, three-dimensional patterns related to the horizontal and vertical distributions of woody fuel as well as the prevailing climate conditions, and the micro-scale patterns of fuel distributions over scales of only meters can determine the path that fire can take through a complex landscape. One challenge in understanding the full three-dimensional (3D) path that a fire takes through a landscape is a lack of data at landscape scales of these burns. Remote sensing approaches, while operating at landscape scales, typically focus on two-dimensional analyses using standard image-based change detection techniques. In this research, we develop a 3D voxel-based change detection method applied to multitemporal LiDAR data collected before and after forest fires in California to quantify the full 3D pattern of vegetation loss. By changing the size of the voxel, forest loss at different spatial scales is revealed. The 3D tunnel of fuel loss created by the fire was used to examine ground-to-crown transitions, firebreaks, and other three-dimensional aspects of a forest fire.

  10. The statistical analysis of multi-voxel patterns in functional imaging.

    Directory of Open Access Journals (Sweden)

    Kai Schreiber

    Full Text Available The goal of multi-voxel pattern analysis (MVPA in BOLD imaging is to determine whether patterns of activation across multiple voxels change with experimental conditions. MVPA is a powerful technique, its use is rapidly growing, but it poses serious statistical challenges. For instance, it is well-known that the slow nature of the BOLD response can lead to greatly exaggerated performance estimates. Methods are available to avoid this overestimation, and we present those here in tutorial fashion. We go on to show that, even with these methods, standard tests of significance such as Students' T and the binomial tests are invalid in typical MRI experiments. Only a carefully constructed permutation test correctly assesses statistical significance. Furthermore, our simulations show that performance estimates increase with both temporal as well as spatial signal correlations among multiple voxels. This dependence implies that a comparison of MVPA performance between areas, between subjects, or even between BOLD signals that have been preprocessed in different ways needs great care.

  11. Design of a novel digital phantom for EIT system calibration.

    Science.gov (United States)

    Li, Nan; Wang, Wei; Xu, Hui

    2011-01-01

    This paper presented the design method of a novel digital phantom for electrical impedance tomography system calibration. By current sensing, voltage generating circuitry and digital processing algorithms implemented in FPGA, the digital phantom can simulate different impedances of tissues. The hardware of the digital phantom mainly consists of current sensing section, voltage generating section, electrodes switching section and a FPGA. Concerning software, the CORDIC algorithm is implemented in the FPGA to realize direct digital synthesis (DDS) technique and related algorithms. Simulation results show that the suggested system exhibits sufficient accuracy in the frequency range 10 Hz to 2 MHz. With the advantages offered by digital techniques, our approach has the potential of speed, accuracy and flexibility of the EIT system calibration process.

  12. Ballistic gelatin as a putative substrate for EEG phantom devices

    CERN Document Server

    Hairston, W David; Yu, Alfred B

    2016-01-01

    Phantom devices allow the human variable to be controlled for in order to allow clear comparison and validation of biomedical imaging hardware and software. There is currently no standard phantom for electroencephalography (EEG). To be useful, such a device would need to: (a) accurately recreate the real and imaginary components of scalp electrical impedance, (b) contain internal emitters to create electrical dipoles, and (c) be easily replicable across various labs and research groups. Cost-effective materials, which are conductive, repeatable, and easily formed are a missing key enabler for EEG phantoms. Here, we explore the use of ballistics gelatin, an inexpensive, easily-formable and repeatable material, as a putative substrate by examining its electrical properties and physical stability over time. We show that varied concentrations of NaCl salt relative to gelatin powder shifts the phase/frequency response profile, allowing for selective tuning of the material electrical properties.

  13. Primary motor cortex changes after amputation correlate with phantom limb pain and the ability to move the phantom limb

    DEFF Research Database (Denmark)

    Raffin, Estelle; Richard, Nathalie; Giraux, Pascal;

    2016-01-01

    A substantial body of evidence documents massive reorganization of primary sensory and motor cortices following hand amputation, the extent of which is correlated with phantom limb pain. Many therapies for phantom limb pain are based upon the idea that plastic changes after amputation are maladap......A substantial body of evidence documents massive reorganization of primary sensory and motor cortices following hand amputation, the extent of which is correlated with phantom limb pain. Many therapies for phantom limb pain are based upon the idea that plastic changes after amputation...... are maladaptive and attempt to normalize representations of cortical areas adjacent to the hand area. Recent data suggest, however, that higher levels of phantom pain are associated with stronger local activity and more structural integrity in the missing hand area rather than with reorganization of neighbouring...... body parts. While these models appear to be mutually exclusive they could co-exist, and one reason for the apparent discrepancy between them might be that no single study has examined the organisation of lip, elbow, and hand movements in the same participants. In this study we thoroughly examined the 3...

  14. Design and development of an ultrasound calibration phantom and system

    Science.gov (United States)

    Cheng, Alexis; Ackerman, Martin K.; Chirikjian, Gregory S.; Boctor, Emad M.

    2014-03-01

    Image-guided surgery systems are often used to provide surgeons with informational support. Due to several unique advantages such as ease of use, real-time image acquisition, and no ionizing radiation, ultrasound is a common medical imaging modality used in image-guided surgery systems. To perform advanced forms of guidance with ultrasound, such as virtual image overlays or automated robotic actuation, an ultrasound calibration process must be performed. This process recovers the rigid body transformation between a tracked marker attached to the ultrasound transducer and the ultrasound image. A phantom or model with known geometry is also required. In this work, we design and test an ultrasound calibration phantom and software. The two main considerations in this work are utilizing our knowledge of ultrasound physics to design the phantom and delivering an easy to use calibration process to the user. We explore the use of a three-dimensional printer to create the phantom in its entirety without need for user assembly. We have also developed software to automatically segment the three-dimensional printed rods from the ultrasound image by leveraging knowledge about the shape and scale of the phantom. In this work, we present preliminary results from using this phantom to perform ultrasound calibration. To test the efficacy of our method, we match the projection of the points segmented from the image to the known model and calculate a sum squared difference between each point for several combinations of motion generation and filtering methods. The best performing combination of motion and filtering techniques had an error of 1.56 mm and a standard deviation of 1.02 mm.

  15. A voxel-based investigation for MRI-only radiotherapy of the brain using ultra short echo times

    DEFF Research Database (Denmark)

    Edmund, Jens Morgenthaler; Kjer, Hans Martin; Van Leemput, Koen;

    2014-01-01

    , however, need to be assigned to the MRI images for dose calculation and patient setup based on digitally reconstructed radiographs (DRRs). Here, we investigate the geometric and dosimetric performance for a number of popular voxel-based methods to generate a so-called pseudo CT (pCT). Five patients...... receiving cranial irradiation, each containing a co-registered MRI and CT scan, were included. An ultra short echo time MRI sequence for bone visualization was used. Six methods were investigated for three popular types of voxel-based approaches; (1) threshold-based segmentation, (2) Bayesian segmentation...... including or excluding additional spatial information. Approach 3 used a statistical regression correlating MRI voxels with their corresponding CT voxels. A similar photon and proton treatment plan was generated for a target positioned between the nasal cavity and the brainstem for all patients. The CT...

  16. Viscosity-Induced Crossing of the Phantom Barrier

    Directory of Open Access Journals (Sweden)

    Iver Brevik

    2015-09-01

    Full Text Available We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region at present time t = 0 across the barrier w = −1 into the phantom region in the late universe. The phantom barrier is accordingly not a sharp mathematical divide, but rather a fuzzy concept. We also calculate the limiting forms of various thermodynamical quantities, including the rate of entropy production, for a dark energy fluid near the future Big Rip singularity.

  17. Development of PIMAL: Mathematical Phantom with Moving Arms and Legs

    Energy Technology Data Exchange (ETDEWEB)

    Akkurt, Hatice [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eckerman, Keith F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2007-05-01

    The computational model of the human anatomy (phantom) has gone through many revisions since its initial development in the 1970s. The computational phantom model currently used by the Nuclear Regulatory Commission (NRC) is based on a model published in 1974. Hence, the phantom model used by the NRC staff was missing some organs (e.g., neck, esophagus) and tissues. Further, locations of some organs were inappropriate (e.g., thyroid).Moreover, all the computational phantoms were assumed to be in the vertical-upright position. However, many occupational radiation exposures occur with the worker in other positions. In the first phase of this work, updates on the computational phantom models were reviewed and a revised phantom model, which includes the updates for the relevant organs and compositions, was identified. This revised model was adopted as the starting point for this development work, and hence a series of radiation transport computations, using the Monte Carlo code MCNP5, was performed. The computational results were compared against values reported by the International Commission on Radiation Protection (ICRP) in Publication 74. For some of the organs (e.g., thyroid), there were discrepancies between the computed values and the results reported in ICRP-74. The reasons behind these discrepancies have been investigated and are discussed in this report.Additionally, sensitivity computations were performed to determine the sensitivity of the organ doses for certain parameters, including composition and cross sections used in the simulations. To assess the dose for more realistic exposure configurations, the phantom model was revised to enable flexible positioning of the arms and legs. Furthermore, to reduce the user time for analyses, a graphical user interface (GUI) was developed. The GUI can be used to visualize the positioning of the arms and legs as desired posture is achieved to generate the input file, invoke the computations, and extract the organ dose

  18. Single fiber perfusion phantom for optical coherence tomography

    Science.gov (United States)

    Podlipná, Petra; Kolář, Radim

    2013-06-01

    This paper presents the successful creation of new phantom for optical coherence tomography (OCT) aimed on perfusion simulation. The phantom is created from syringe pump and polypropylene hollow fiber with porous walls embeded in the glass capillary to provide small outer environment. Its function was tested by gold nanorods as a flowing medium and imaged by commercial swept-source OCT system. Results showed that the fiber is permeable for used gold nanorods which are frequently declared as possible contrast agents for OCT and this permeability can be displayed by OCT.

  19. Space radiation absorbed dose distribution in a human phantom

    Science.gov (United States)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  20. CT images of an anthropomorphic and anthropometric male pelvis phantom

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Andrea S.D. de; Campos, Tarcisio P.R. de, E-mail: campos@nuclear.ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares

    2009-07-01

    Actually, among of the most often neoplasm types are the cancer of prostate, bladder and intestine. The incidence of the intestine neoplasm in Brazil is at fourth among the most frequent tumors of the male sex, barely close to the stomach, lung and prostate incidences. Phantoms are objects used as simulators for investigating ionizing radiation transport on humans, especially during radiation therapy or radiological diagnostic. The purpose of this work is the achievement of a set of computerized tomography (CT) images of a male pelvis phantom, with anthropomorphic and anthropometric features. It investigates and analyses the set of phantom CT images in according to a correspondent human pelvis one. The reason to develop a pelvis phantom is the needs of reproducing well established spatial dose distribution in radiation therapy, especially during calibration and protocol setup for various pelvis neoplasms. It aims to produce dose optimization on radiation therapy, improving health tissue protection and keeping control tumor dose. A male pelvis phantom with similar shape made of equivalent tissues was built for simulating the ionizing radiation transport to the human body. At the phantom, pelvis organs were reproduced including the bladder, the intestine, the prostate, the muscular and greasy tissue, as well as the bone tissue and the skin. A set of CT images was carried out in axial thin sections of 2mm thickness. As results, the constituent tissues had a tomography response on Hounsfield scale similar to values found on the human pelvis. Each tissue has its respective Hounsfield value, demonstrated here. The CT images also show that the organs have equivalent anthropometric measures and anthropomorphic features of the radiological human anatomy. The anatomical physical arrangement of the organs is also similar to of the pelvis human male, having the scales of gray and numerical scale of Hounsfield compatible with the scale of the human tissue. The phantom presents