WorldWideScience

Sample records for human head phantom

  1. Wireless Performance of a Fully Passive Neurorecording Microsystem Embedded in Dispersive Human Head Phantom

    Science.gov (United States)

    Schwerdt, Helen N.; Chae, Junseok; Miranda, Felix A.

    2012-01-01

    This paper reports the wireless performance of a biocompatible fully passive microsystem implanted in phantom media simulating the dispersive dielectric properties of the human head, for potential application in recording cortical neuropotentials. Fully passive wireless operation is achieved by means of backscattering electromagnetic (EM) waves carrying 3rd order harmonic mixing products (2f(sub 0) plus or minus f(sub m)=4.4-4.9 GHZ) containing targeted neuropotential signals (fm approximately equal to 1-1000 Hz). The microsystem is enclosed in 4 micrometer thick parylene-C for biocompatibility and has a footprint of 4 millimeters x 12 millimeters x 500 micrometers. Preliminary testing of the microsystem implanted in the lossy biological simulating media results in signal-to-noise ratio's (SNR) near 22 (SNR approximately equal to 38 in free space) for millivolt level neuropotentials, demonstrating the potential for fully passive wireless microsystems in implantable medical applications.

  2. A Study Of EMR And SAR Distribution In Human Head Phantom ...

    African Journals Online (AJOL)

    power of 0.32W for both simulations were well below the limit of 1.6 W/kg of ICNIRP standard and FCC/IEEE standard of 2W/kg. Keywords: Electromagnetic radiation (EMR), Specific Absorption Rate (SAR), Electromagnetic simulation software (FEKO emss), Radio frequency field, human head, mobile phone, mobile phone ...

  3. 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.  

  4. Analysis of mobile phone design features affecting radiofrequency power absorbed in a human head phantom.

    Science.gov (United States)

    Kuehn, Sven; Kelsh, Michael A; Kuster, Niels; Sheppard, Asher R; Shum, Mona

    2013-09-01

    The US FCC mandates the testing of all mobile phones to demonstrate compliance with the rule requiring that the peak spatial SAR does not exceed the limit of 1.6 W/kg averaged over any 1 g of tissue. These test data, measured in phantoms with mobile phones operating at maximum antenna input power, permitted us to evaluate the variation in SARs across mobile phone design factors such as shape and antenna design, communication technology, and test date (over a 7-year period). Descriptive statistical summaries calculated for 850 MHz and 1900 MHz phones and ANOVA were used to evaluate the influence of the foregoing factors on SARs. Service technology accounted for the greatest variability in compliance test SARs that ranged from AMPS (highest) to CDMA, iDEN, TDMA, and GSM (lowest). However, the dominant factor for SARs during use is the time-averaged antenna input power, which may be much less than the maximum power used in testing. This factor is largely defined by the communication system; e.g., the GSM phone average output can be higher than CDMA by a factor of 100. Phone shape, antenna type, and orientation of a phone were found to be significant but only on the order of up to a factor of 2 (3 dB). The SAR in the tilt position was significantly smaller than for touch. The side of the head did not affect SAR levels significantly. Among the remaining factors, external antennae produced greater SARs than internal ones, and brick and clamshell phones produced greater SARs than slide phones. Assuming phone design and usage patterns do not change significantly over time, we have developed a normalization procedure and formula that permits reliable prediction of the relative SAR between various communication systems. This approach can be applied to improve exposure assessment in epidemiological research. Copyright © 2013 Wiley Periodicals, Inc.

  5. Computerized Virtual Reality Simulation in Preclinical Dentistry: Can a Computerized Simulator Replace the Conventional Phantom Heads and Human Instruction?

    Science.gov (United States)

    Plessas, Anastasios

    2017-10-01

    In preclinical dental education, the acquisition of clinical, technical skills, and the transfer of these skills to the clinic are paramount. Phantom heads provide an efficient way to teach preclinical students dental procedures safely while increasing their dexterity skills considerably. Modern computerized phantom head training units incorporate features of virtual reality technology and the ability to offer concurrent augmented feedback. The aims of this review were to examine and evaluate the dental literature for evidence supporting their use and to discuss the role of augmented feedback versus the facilitator's instruction. Adjunctive training in these units seems to enhance student's learning and skill acquisition and reduce the required faculty supervision time. However, the virtual augmented feedback cannot be used as the sole method of feedback, and the facilitator's input is still critical. Well-powered longitudinal randomized trials exploring the impact of these units on student's clinical performance and issues of cost-effectiveness are warranted.

  6. Comparison of the local dose of scattered radiation of a special dental - phantom and a real human head by using a Digital Volume Tomography (DVT)

    International Nuclear Information System (INIS)

    Neuwirth, J.; Hefner, A.

    2008-01-01

    Dental Radiography Digital Volume Tomography (DVT) gains more and more importance due to its possibility of three-dimensional imaging of teeth, jaw and visercoranium and the reduced radiation dose in comparison to conventional Computer Tomography (CT). Contrary to other, well documented radiographic procedures like dental panorama X-ray imaging there are no national or international guidelines or recommendations relating to DVT which regulate the designation of areas and standardize risk assessment. This study aims to assess the parameters necessary for local radiation protection in dental practices. Measurements were carried out in dental practices in order to evaluate the local dose resulting from different DVT devices. A special dental-phantom and a real human head were used in the irradiations in order to define the local dose of scattered radiation by nominal voltage. The dental-phantom was created for conventional dental panorama X-ray devices which make use of lower nominal voltages. This poses the question if the scatter performance of the special dental-phantom is comparable to a real human head and therefore applicable to the estimation of the radiation quality of a DVT when using 120 kV. The existing guidelines for dental panorama xray are analyzed and suggestions for future recommendations concerning the designation of areas and risk assessment for DVT are then deducted by comparing both sets of measurements. The results show that the special dental-phantom is absolutely suitable for the definition of the local dose resulting from the scattered radiation of a DVT. (author)

  7. Design and fabrication of a realistic anthropomorphic heterogeneous head phantom for MR purposes.

    Directory of Open Access Journals (Sweden)

    Sossena Wood

    Full Text Available The purpose of this study is to design an anthropomorphic heterogeneous head phantom that can be used for MRI and other electromagnetic applications.An eight compartment, physical anthropomorphic head phantom was developed from a 3T MRI dataset of a healthy male. The designed phantom was successfully built and preliminarily evaluated through an application that involves electromagnetic-tissue interactions: MRI (due to it being an available resource. The developed phantom was filled with media possessing electromagnetic constitutive parameters that correspond to biological tissues at ~297 MHz. A preliminary comparison between an in-vivo human volunteer (based on whom the anthropomorphic head phantom was created and various phantoms types, one being the anthropomorphic heterogeneous head phantom, were performed using a 7 Tesla human MRI scanner.Echo planar imaging was performed and minimal ghosting and fluctuations were observed using the proposed anthropomorphic phantom. The magnetic field distributions (during MRI experiments at 7 Tesla and the scattering parameter (measured using a network analyzer were most comparable between the anthropomorphic heterogeneous head phantom and an in-vivo human volunteer.The developed anthropomorphic heterogeneous head phantom can be used as a resource to various researchers in applications that involve electromagnetic-biological tissue interactions such as MRI.

  8. Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface. Cooperative research

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Uchiyama, Junzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Endo, Kiyoshi; Yamamoto, Tetsuya; Matsumura, Akira; Nose, Tadao [Tsukuba Univ., Tsukuba, Ibaraki (Japan)

    2002-12-01

    Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient. (author)

  9. Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface. Cooperative research

    CERN Document Server

    Yamamoto, K; Kishi, T; Kumada, H; Matsumura, A; Nose, T; Torii, Y; Uchiyama, J; Yamamoto, T

    2002-01-01

    Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient.

  10. Influence of dentures on SAR in the visible Chinese human head voxel phantom exposed to a mobile phone at 900 and 1800 MHz.

    Science.gov (United States)

    Yu, Dong; Zhang, Ruoyu; Liu, Qian

    2012-09-01

    To investigate the influence of dentures on electromagnetic energy absorption during the daily use of a mobile phone, a high-resolution head phantom based on the Visible Chinese Human dataset was reconstructed. Simulations on phantoms with various dentures were performed by using the finite-difference time-domain method with a 0.47 wavelength dipole antenna and a mobile phone model as radiation sources at 900 and 1800 MHz. The Specific energy Absorption Rate (SAR) values including 1 and 10 g average SAR values were assessed. When the metallic dental crowns with resonance lengths of approximately one-third to one-half wavelength in the tissue nearby are parallel to the radiation source, up to 121.6% relative enhancement for 1 g average SAR and 17.1% relative enhancement for 10 g average SAR are observed due to the resonance effect in energy absorption. When the radiation sources operate in the normal configuration, the 10 g average SAR values are still in compliance with the basic restrictions established by the Institute of Electrical and Electronic Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP), indicating that the safety limits will not be challenged by the usage of dentures. Copyright © 2012 Wiley Periodicals, Inc.

  11. Absorbed dose estimates to structures of the brain and head using a high-resolution voxel-based head phantom

    International Nuclear Information System (INIS)

    Evans, Jeffrey F.; Blue, Thomas E.; Gupta, Nilendu

    2001-01-01

    The purpose of this article is to demonstrate the viability of using a high-resolution 3-D head phantom in Monte Carlo N-Particle (MCNP) for boron neutron capture therapy (BNCT) structure dosimetry. This work describes a high-resolution voxel-based model of a human head and its use for calculating absorbed doses to the structures of the brain. The Zubal head phantom is a 3-D model of a human head that can be displayed and manipulated on a computer. Several changes were made to the original head phantom which now contains over 29 critical structures of the brain and head. The modified phantom is a 85x109x120 lattice of voxels, where each voxel is 2.2x2.2x1.4 mm 3 . This model was translated into MCNP lattice format. As a proof of principle study, two MCNP absorbed dose calculations were made (left and right lateral irradiations) using a uniformly distributed neutron disk source with an 1/E energy spectrum. Additionally, the results of these two calculations were combined to estimate the absorbed doses from a bilateral irradiation. Radiobiologically equivalent (RBE) doses were calculated for all structures and were normalized to 12.8 Gy-Eq. For a left lateral irradiation, the left motor cortex receives the limiting RBE dose. For a bilateral irradiation, the insula cortices receive the limiting dose. Among the nonencephalic structures, the parotid glands receive RBE doses that were within 15% of the limiting dose

  12. Verification of gamma knife based fractionated radiosurgery with newly developed head-thorax phantom

    International Nuclear Information System (INIS)

    Bisht, Raj Kishor; Kale, Shashank Sharad; Natanasabapathi, Gopishankar; Singh, Manmohan Jit; Agarwal, Deepak; Garg, Ajay; Rath, Goura Kishore; Julka, Pramod Kumar; Kumar, Pratik; Thulkar, Sanjay; Sharma, Bhawani Shankar

    2016-01-01

    Objective: Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fractionated stereotactic radiosurgery with newly developed head-thorax phantom. Methods: Phantoms are extensively used to measure radiation dose and verify treatment plan in radiotherapy. A human upper body shaped phantom with thorax was designed to simulate fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife. The central component of the phantom aids in performing radiological precision test, dosimetric evaluation and treatment verification. A hollow right circular cylindrical space of diameter 7.0 cm was created at the centre of this component to place various dosimetric devices using suitable adaptors. The phantom is made of poly methyl methacrylate (PMMA), a transparent thermoplastic material. Two sets of disk assemblies were designed to place dosimetric films in (1) horizontal (xy) and (2) vertical (xz) planes. Specific cylindrical adaptors were designed to place thimble ionization chamber inside phantom for point dose recording along xz axis. EBT3 Gafchromic films were used to analyze and map radiation field. The focal precision test was performed using 4 mm collimator shot in phantom to check radiological accuracy of treatment. The phantom head position within the Extend™ frame was estimated using encoded aperture measurement of repositioning check tool (RCT). For treatment verification, the phantom with inserts for film and ion chamber was scanned in reference treatment position using X-ray computed tomography (CT) machine and acquired stereotactic images were transferred into Leksell Gammaplan (LGP). A patient treatment plan with hypo-fractionated regimen was delivered and identical fractions were compared using EBT3 films and in-house MATLAB codes. Results: RCT measurement showed an overall positional accuracy of 0.265 mm (range 0.223 mm–0.343 mm). Gamma index analysis across fractions exhibited close agreement between LGP and film

  13. Low earth orbit radiation dose distribution in a phantom head

    International Nuclear Information System (INIS)

    Konradi, A.; Badhwar, G.D.; Cash, B.L.; Hardy, K.A.

    1992-01-01

    In order to compare analytical methods with data obtained during exposure to space radiation, a phantom head instrumented with a large number of radiation detectors was flown on the Space Shuttle on three occasions: 8 August 1989 (STS-28), 28 February 1990 (STS-36), and 24 April 1990 (STS-31). The objective of this experiment was to obtain a measurement of the inhomogeneity in the dose distribution within a phantom head volume. The orbits of these missions were complementary-STS-28 and STS-36 had high inclination and low altitude, while STS-31 had a low inclination and high altitude. In the cases of STS-28 and STS-36, the main contribution to the radiation dose comes from galactic cosmic rays (GCR) with a minor to negligible part supplied by the inner belt through the South Atlantic Anomaly (SAA), and for STS-28 an even smaller one from a proton enhancement during a solar flare-associated proton event. For STS-31, the inner belt protons dominate and the GCR contribution is almost negligible. The internal dose distribution is consistent with the mass distribution of the orbiter and the self-shielding and physical location of the phantom head. (author)

  14. Induction and separation of motion artifacts in EEG data using a mobile phantom head device.

    Science.gov (United States)

    Oliveira, Anderson S; Schlink, Bryan R; Hairston, W David; König, Peter; Ferris, Daniel P

    2016-06-01

    Electroencephalography (EEG) can assess brain activity during whole-body motion in humans but head motion can induce artifacts that obfuscate electrocortical signals. Definitive solutions for removing motion artifact from EEG have yet to be found, so creating methods to assess signal processing routines for removing motion artifact are needed. We present a novel method for investigating the influence of head motion on EEG recordings as well as for assessing the efficacy of signal processing approaches intended to remove motion artifact. We used a phantom head device to mimic electrical properties of the human head with three controlled dipolar sources of electrical activity embedded in the phantom. We induced sinusoidal vertical motions on the phantom head using a custom-built platform and recorded EEG signals with three different acquisition systems while the head was both stationary and in varied motion conditions. Recordings showed up to 80% reductions in signal-to-noise ratio (SNR) and up to 3600% increases in the power spectrum as a function of motion amplitude and frequency. Independent component analysis (ICA) successfully isolated the three dipolar sources across all conditions and systems. There was a high correlation (r > 0.85) and marginal increase in the independent components' (ICs) power spectrum (∼15%) when comparing stationary and motion parameters. The SNR of the IC activation was 400%-700% higher in comparison to the channel data SNR, attenuating the effects of motion on SNR. Our results suggest that the phantom head and motion platform can be used to assess motion artifact removal algorithms and compare different EEG systems for motion artifact sensitivity. In addition, ICA is effective in isolating target electrocortical events and marginally improving SNR in relation to stationary recordings.

  15. Monte Carlo and experimental internal radionuclide dosimetry in RANDO head phantom

    International Nuclear Information System (INIS)

    Ghahraman Asl, Ruhollah; Nasseri, Shahrokh; Parach, Ali Asghar; Zakavi, Seyed Rasoul; Momennezhad Mehdi; Davenport, David

    2015-01-01

    Monte Carlo techniques are widely employed in internal dosimetry to obtain better estimates of absorbed dose distributions from irradiation sources in medicine. Accurate 3D absorbed dosimetry would be useful for risk assessment of inducing deterministic and stochastic biological effects for both therapeutic and diagnostic radiopharmaceuticals in nuclear medicine. The goal of this study was to experimentally evaluate the use of Geant4 application for tomographic emission (GATE) Monte Carlo package for 3D internal dosimetry using the head portion of the RANDO phantom. GATE package (version 6.1) was used to create a voxel model of a human head phantom from computed tomography (CT) images. Matrix dimensions consisted of 319 × 216 × 30 voxels (0.7871 × 0.7871 × 5 mm 3 ). Measurements were made using thermoluminescent dosimeters (TLD-100). One rod-shaped source with 94 MBq activity of 99m Tc was positioned in the brain tissue of the posterior part of the human head phantom in slice number 2. The results of the simulation were compared with measured mean absorbed dose per cumulative activity (S value). Absorbed dose was also calculated for each slice of the digital model of the head phantom and dose volume histograms (DVHs) were computed to analyze the absolute and relative doses in each slice from the simulation data. The S-values calculated by GATE and TLD methods showed a significant correlation (correlation coefficient, r 2 ≥ 0.99, p < 0.05) with each other. The maximum relative percentage differences were ≤14 % for most cases. DVHs demonstrated dose decrease along the direction of movement toward the lower slices of the head phantom. Based on the results obtained from GATE Monte Carlopackage it can be deduced that a complete dosimetry simulation study, from imaging to absorbed dose map calculation, is possible to execute in a single framework.

  16. Computed tomography scan optimization using head phantom and radiochromic films

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Lorena C.; Santana, P.C.; Velasquez, Carlos E.; Mourao, Arnaldo P., E-mail: lorena.cfernandes@hotmail.com, E-mail: carlosvelcab@hotmail.com, E-mail: pridili@gmail.com, E-mail: apmourao@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear; Centro de Imagem Molecular do INCT-Medicina Molecular (CIMol/UFMG) Belo Horizonte (Brazil); Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Belo Horizonte (Brazil)

    2017-11-01

    The research and development in technology applied to computed tomography has been improve in the image quality, resulting in the best identification of diseases, and therefore an increase in the number of exams, among them the head exams can be highlighted. In order to promote a radioprotection and reduction on the dose of the general public some international agencies have stipulated dose limits to be followed and the implementation of the principles of ALARA in all establishments that use ionizing radiation. One of these principles is the optimization that should be treated with substantial attention, because the reduction of radiation doses can be feasible as long as it does not compromise the tomographic images; such practice is difficult to perform due to the lack of proper guidance. In optimization of the CT exams, not only the lowest dose is evaluated to obtain diagnostic image, but also should be knowledge the dose distribution throughout the scanned area. In this work were used a cylindrical head phantom of PMMA, a GE Discovery CT scan with 64 channels, and radiochromic films. The films were positioned in the phantom in their central region for the dose evaluation using the automatic control for the voltages of 80, 100 and 120 kV. The images were acquired from the scan of the phantom and the film readings were obtained through digital images. The results show an evaluation of the longitudinal kerma profiles, dose delivered, and the image noise was also observed using the central slice images. (author)

  17. Computed tomography scan optimization using head phantom and radiochromic films

    International Nuclear Information System (INIS)

    Fernandes, Lorena C.; Santana, P.C.; Velasquez, Carlos E.; Mourao, Arnaldo P.

    2017-01-01

    The research and development in technology applied to computed tomography has been improve in the image quality, resulting in the best identification of diseases, and therefore an increase in the number of exams, among them the head exams can be highlighted. In order to promote a radioprotection and reduction on the dose of the general public some international agencies have stipulated dose limits to be followed and the implementation of the principles of ALARA in all establishments that use ionizing radiation. One of these principles is the optimization that should be treated with substantial attention, because the reduction of radiation doses can be feasible as long as it does not compromise the tomographic images; such practice is difficult to perform due to the lack of proper guidance. In optimization of the CT exams, not only the lowest dose is evaluated to obtain diagnostic image, but also should be knowledge the dose distribution throughout the scanned area. In this work were used a cylindrical head phantom of PMMA, a GE Discovery CT scan with 64 channels, and radiochromic films. The films were positioned in the phantom in their central region for the dose evaluation using the automatic control for the voltages of 80, 100 and 120 kV. The images were acquired from the scan of the phantom and the film readings were obtained through digital images. The results show an evaluation of the longitudinal kerma profiles, dose delivered, and the image noise was also observed using the central slice images. (author)

  18. Radiological response and dosimetry in physical phantom of head and neck for 3D conformational radiotherapy

    International Nuclear Information System (INIS)

    Thompson, Larissa

    2013-01-01

    Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film

  19. Development and application of a pediatric head phantom for dosimetry in computed tomography

    International Nuclear Information System (INIS)

    Martins, Elaine Wirney

    2016-01-01

    To determine the exposure levels and the absorbed dose in patients undergoing CT scans, is necessary to calculate the CT dose index in measurements with a PMMA or water phantom. The phantom must be enough to simulate the attenuation and scattering characteristics of a human body or parts in a radiation field. The CT specific quantities : CT air kerma index (Ca,100) , weighted CT air kerma index (CW ), a total volume CT air kerma index (Cvol) and the CT air kerma-length product (PKL) must be determined and compared to literature reference levels. In this work a head pediatric phantom was developed, considering that the Brazilian published Diagnostic Reference Levels (DRL) are based on adult phantom measurements. This developed phantom shows a construction innovation using materials to simulate the skullcap, cortical bone (aluminum) and cancellous bone (PVC), and it was filled with distilled water. The phantom dimension follows the recommendations of the World Health Organization and the International Commission on Radiation Units for children from 0 to 5 years old head size: diameter of 160 mm and height of 155 mm. The skullcap has 4 mm of thickness and 111.9 mm of internal diameter. In order to evaluate its behavior, tests were carried out in calibration laboratories and in clinical beams. The results showed attenuation up to 23% when different materials are used as skullcap, demonstrating that the DRLs adopted could be overestimating the dose received by pediatric patients. It is observed that the dose received by CT skull scans presents different distribution, due to the skullcap partially attenuation and/or backscattering which is not considered when the PMMA phantom is used.

  20. A new head phantom with realistic shape and spatially varying skull resistivity distribution.

    Science.gov (United States)

    Li, Jian-Bo; Tang, Chi; Dai, Meng; Liu, Geng; Shi, Xue-Tao; Yang, Bin; Xu, Can-Hua; Fu, Feng; You, Fu-Sheng; Tang, Meng-Xing; Dong, Xiu-Zhen

    2014-02-01

    Brain electrical impedance tomography (EIT) is an emerging method for monitoring brain injuries. To effectively evaluate brain EIT systems and reconstruction algorithms, we have developed a novel head phantom that features realistic anatomy and spatially varying skull resistivity. The head phantom was created with three layers, representing scalp, skull, and brain tissues. The fabrication process entailed 3-D printing of the anatomical geometry for mold creation followed by casting to ensure high geometrical precision and accuracy of the resistivity distribution. We evaluated the accuracy and stability of the phantom. Results showed that the head phantom achieved high geometric accuracy, accurate skull resistivity values, and good stability over time and in the frequency domain. Experimental impedance reconstructions performed using the head phantom and computer simulations were found to be consistent for the same perturbation object. In conclusion, this new phantom could provide a more accurate test platform for brain EIT research.

  1. Design of a head phantom produced on a 3D rapid prototyping printer and comparison with a RANDO and 3M lucite head phantom in eye dosimetry applications.

    Science.gov (United States)

    Homolka, Peter; Figl, Michael; Wartak, Andreas; Glanzer, Mathias; Dünkelmeyer, Martina; Hojreh, Azadeh; Hummel, Johann

    2017-04-21

    An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using a photo-cured acrylic resin to best allow tissue equivalence. Thus H p (3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface. A comparison of dose reduction factors (DRFs) of a common lead glasses model has also been performed. Eye dose per incident air kerma were comparable between all three phantoms (printed phantom: 1.40, standard error (SE) 0.04; RANDO: 1.36, SE 0.03; 3M: 1.37, SE 0.03). Doses to the forehead were identical to eye surface doses for the printed phantom and the RANDO head (ratio 1.00 SE 0.04, and 0.99 SE 0.03, respectively). In the 3M Lucite skull phantom dose on the forehead was 15% lower than dose to the eyes attributable to phantom properties. DRF of a sport frame style leaded glasses model with 0.75 mm lead equivalence measured were 6.8 SE 0.5, 9.3 SE 0.4 and 10.5 SE 0.5 for the RANDO head, the printed phantom, and the 3M Lucite head phantom, respectively, for frontal irradiation. A comparison of doses measured in 3 mm depth and on the surface of the eyes in the printed phantom revealed no difference larger than standard errors from TLD dosimetry. 3D printing offers an interesting opportunity for phantom design with increasing potential as printers allowing combinations of tissue substitutes will become available. Variations between phantoms may provide a useful indication of uncertainty budgets when using phantom measurements to estimate individual personnel doses.

  2. Development of a high resolution voxelised head phantom for medical physics applications.

    Science.gov (United States)

    Giacometti, V; Guatelli, S; Bazalova-Carter, M; Rosenfeld, A B; Schulte, R W

    2017-01-01

    Computational anthropomorphic phantoms have become an important investigation tool for medical imaging and dosimetry for radiotherapy and radiation protection. The development of computational phantoms with realistic anatomical features contribute significantly to the development of novel methods in medical physics. For many applications, it is desirable that such computational phantoms have a real-world physical counterpart in order to verify the obtained results. In this work, we report the development of a voxelised phantom, the HIGH_RES_HEAD, modelling a paediatric head based on the commercial phantom 715-HN (CIRS). HIGH_RES_HEAD is unique for its anatomical details and high spatial resolution (0.18×0.18mm 2 pixel size). The development of such a phantom was required to investigate the performance of a new proton computed tomography (pCT) system, in terms of detector technology and image reconstruction algorithms. The HIGH_RES_HEAD was used in an ad-hoc Geant4 simulation modelling the pCT system. The simulation application was previously validated with respect to experimental results. When compared to a standard spatial resolution voxelised phantom of the same paediatric head, it was shown that in pCT reconstruction studies, the use of the HIGH_RES_HEAD translates into a reduction from 2% to 0.7% of the average relative stopping power difference between experimental and simulated results thus improving the overall quality of the head phantom simulation. The HIGH_RES_HEAD can also be used for other medical physics applications such as treatment planning studies. A second version of the voxelised phantom was created that contains a prototypic base of skull tumour and surrounding organs at risk. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. Reducing dose in head CT: A phantom study

    International Nuclear Information System (INIS)

    Perez Diaz, M.; Carvalho, A. E.; Andrade, M. E.; Khoury, H. J.

    2013-01-01

    Thirty two head CT scans were acquired employing an anthropomorphic phantom which contains small lesions in posterior fosse, using 2 scanners, one with 64 slices 'Siemens Sensation' and other with 6 slices P hilip Brilliance . Parameters as Tube current (I [mA]), Collimation (C [mm]), spectrum energy (kVp) and dynamic range were changed during studies, looking for the optimal acquisition/processing conditions which permit both, good lesion detectability and the lowest dose. Air kerma (mGy) was measured with a ionization chamber and the air kerma index (Ca,100 [mGy]) was calculated as dose index. Image quality was analyzed by 5 expert criteria using a 5 points-scale (1=poor, 2=fair, 3=good, 4=very good, 5=excellent) and also using 5 Figure of merit in the spatial and frequency domains: Contrast C(%), Contrast to Noise Ratio CNR, Signal to Noise Ratio SNR, Normalized Mean Square Error (NMSE) and the Spectral Distance (SD). Objective and subjective results were correlated. We observed that doses can be diminished until a 25% respect to the usual practice with both technologies, diminishing mainly the mAs, without affecting lesion detection. As a result, we propose an optimized protocol for each scanner as follow: The use of 250 mAs, 120 kVp and the collimation of 6 slices x 1.50 mm per rotation to detect the lesions in posterior fosse with good image quality for the Philips Brilliance 6 tested, while 150 mAs, 100 kVp and slice thickness of 3 mm were needed with the Siemens Sensation 64. (Author)

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

    International Nuclear Information System (INIS)

    Kiarashi, Nooshin; Nolte, Adam C.; Sturgeon, Gregory M.; Ghate, Sujata V.; Segars, William P.; Nolte, Loren W.; Samei, Ehsan

    2015-01-01

    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

  5. 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

  6. Composition of MRI phantom equivalent to human tissues

    International Nuclear Information System (INIS)

    Kato, Hirokazu; Kuroda, Masahiro; Yoshimura, Koichi; Yoshida, Atsushi; Hanamoto, Katsumi; Kawasaki, Shoji; Shibuya, Koichi; Kanazawa, Susumu

    2005-01-01

    We previously developed two new MRI phantoms (called the CAG phantom and the CAGN phantom), with T1 and T2 relaxation times equivalent to those of any human tissue at 1.5 T. The conductivity of the CAGN phantom is equivalent to that of most types of human tissue in the frequency range of 1 to 130 MHz. In this paper, the relaxation times of human tissues are summarized, and the composition of the corresponding phantoms are provided in table form. The ingredients of these phantoms are carrageenan as the gelling agent, GdCl 3 as a T1 modifier, agarose as a T2 modifier, NaCl (CAGN phantom only) as a conductivity modifier, NaN 3 as an antiseptic, and distilled water. The phantoms have T1 values of 202-1904 ms and T2 values of 38-423 ms when the concentrations of GdCl 3 and agarose are varied from 0-140 μmol/kg, and 0%-1.6%, respectively, and the CAGN phantom has a conductivity of 0.27-1.26 S/m when the NaCl concentration is varied from 0%-0.7%. These phantoms have sufficient strength to replicate a torso without the use of reinforcing agents, and can be cut by a knife into any shape. We anticipate the CAGN phantom to be highly useful and practical for MRI and hyperthermia-related research

  7. SU-G-206-05: A Comparison of Head Phantoms Used for Dose Determination in Imaging Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Z; Vijayan, S; Kilian-Meneghin, J; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

    2016-06-15

    Purpose: To determine similarities and differences between various head phantoms that might be used for dose measurements in diagnostic imaging procedures. Methods: We chose four frequently used anthropomorphic head phantoms (SK-150, PBU-50, RS-240T and Alderson Rando), a computational patient phantom (Zubal) and the CTDI head phantom for comparison in our study. We did a CT scan of the head phantoms using the same protocol and compared their dimensions and CT numbers. The scan data was used to calculate dose values for each of the phantoms using EGSnrc Monte Carlo software. An .egsphant file was constructed to describe these phantoms using a Visual C++ program for DOSXYZnrc/EGSnrc simulation. The lens dose was calculated for a simulated CBCT scan using DOSXYZnrc/EGSnrc and the calculated doses were validated with measurements using Gafchromic film and an ionization chamber. Similar calculations and measurements were made for PA radiography to investigate the attenuation and backscatter differences between these phantoms. We used the Zubal phantom as the standard for comparison since it was developed based on a CT scan of a patient. Results: The lens dose for the Alderson Rando phantom is around 9% different than the Zubal phantom, while the lens dose for the PBU-50 phantom was about 50% higher, possibly because its skull thickness and the density of bone and soft tissue are lower than anthropometric values. The lens dose for the CTDI phantom is about 500% higher because of its totally different structure. The entrance dose profiles are similar for the five anthropomorphic phantoms, while that for the CTDI phantom was distinctly different. Conclusion: The CTDI and PBU-50 head phantoms have substantially larger lens dose estimates in CBCT. The other four head phantoms have similar entrance dose with backscatter hence should be preferred for dose measurement in imaging procedures of the head. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems

  8. Radiation dose evaluation of dental cone beam computed tomography using an anthropomorphic adult head phantom

    Science.gov (United States)

    Wu, Jay; Shih, Cheng-Ting; Ho, Chang-hung; Liu, Yan-Lin; Chang, Yuan-Jen; Min Chao, Max; Hsu, Jui-Ting

    2014-11-01

    Dental cone beam computed tomography (CBCT) provides high-resolution tomographic images and has been gradually used in clinical practice. Thus, it is important to examine the amount of radiation dose resulting from dental CBCT examinations. In this study, we developed an in-house anthropomorphic adult head phantom to evaluate the level of effective dose. The anthropomorphic phantom was made of acrylic and filled with plaster to replace the bony tissue. The contour of the head was extracted from a set of adult computed tomography (CT) images. Different combinations of the scanning parameters of CBCT were applied. Thermoluminescent dosimeters (TLDs) were used to measure the absorbed doses at 19 locations in the head and neck regions. The effective doses measured using the proposed phantom at 65, 75, and 85 kVp in the D-mode were 72.23, 100.31, and 134.29 μSv, respectively. In the I-mode, the effective doses were 108.24, 190.99, and 246.48 μSv, respectively. The maximum percent error between the doses measured by the proposed phantom and the Rando phantom was l4.90%. Therefore, the proposed anthropomorphic adult head phantom is applicable for assessing the radiation dose resulting from clinical dental CBCT.

  9. Dose profile study in head CT scans using a male anthropomorphic phantom

    International Nuclear Information System (INIS)

    Gomez, Alvaro M.L.; Santana, Priscila do C.; Mourao, Arnaldo P.

    2017-01-01

    Computed tomography (CT) test is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in the patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. An anthropomorphic adult male phantom was used and radiochromic film strips were placed to measure the absorbed dose deposited in areas such as the lens, thyroid and pituitary for study of dose deposited in these important areas containing high radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans. (author)

  10. Dose profile study in head CT scans using a male anthropomorphic phantom

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Alvaro M.L.; Santana, Priscila do C.; Mourao, Arnaldo P., E-mail: amlgphys@gmail.com, E-mail: pridili@gmail.com, E-mail: apratabhz@gmail.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear; Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)

    2017-11-01

    Computed tomography (CT) test is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in the patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. An anthropomorphic adult male phantom was used and radiochromic film strips were placed to measure the absorbed dose deposited in areas such as the lens, thyroid and pituitary for study of dose deposited in these important areas containing high radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans. (author)

  11. Averaged head phantoms from magnetic resonance images of Korean children and young adults

    Science.gov (United States)

    Han, Miran; Lee, Ae-Kyoung; Choi, Hyung-Do; Jung, Yong Wook; Park, Jin Seo

    2018-02-01

    Increased use of mobile phones raises concerns about the health risks of electromagnetic radiation. Phantom heads are routinely used for radiofrequency dosimetry simulations, and the purpose of this study was to construct averaged phantom heads for children and young adults. Using magnetic resonance images (MRI), sectioned cadaver images, and a hybrid approach, we initially built template phantoms representing 6-, 9-, 12-, 15-year-old children and young adults. Our subsequent approach revised the template phantoms using 29 averaged items that were identified by averaging the MRI data from 500 children and young adults. In females, the brain size and cranium thickness peaked in the early teens and then decreased. This is contrary to what was observed in males, where brain size and cranium thicknesses either plateaued or grew continuously. The overall shape of brains was spherical in children and became ellipsoidal by adulthood. In this study, we devised a method to build averaged phantom heads by constructing surface and voxel models. The surface model could be used for phantom manipulation, whereas the voxel model could be used for compliance test of specific absorption rate (SAR) for users of mobile phones or other electronic devices.

  12. Dosimetric study on head CT scans using adult and newborn phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Paiva de O, G. A.; Prata M, A., E-mail: giovanni_paiva@hotmail.com [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

    2016-10-15

    Computed tomography is the radiodiagnostic method that most contributes to the dose deposition in population. Therefore, the dose reductions used in these tests are very important, especially for pediatric patients who have a life expectancy greater than the rest of the population. This study purpose to compare the doses generated from newborns compared to adult patients in head computed tomography scans. Two head phantoms in a cylindrical shape made in PMMA were used, one to adult and another to newborn patient dimensions. The pediatric routine scan protocol from a radiological service was used for the computed tomography scans. They were performed in General Electric Computed Tomography scanner, Bright Speed model with 4 channels. The absorbed dose measurements were performed with a pencil chamber placed into both phantoms. The newborn head phantom was developed in order to compare the amount of absorbed dose by the phantoms when it is used the same acquisition protocol. The dose found for newborn phantom was 29.9% higher than the adult phantom. (Author)

  13. Construction of voxel head phantom and application to BNCT dose calculation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choon Sik; Lee, Choon Ik; Lee, Jai Ki [Hanyang Univ., Seoul (Korea, Republic of)

    2001-06-15

    Voxel head phantom for overcoming the limitation of mathematical phantom in depicting anatomical details was constructed and example dose calculation for BNCT was performed. The repeated structure algorithm of the general purpose Monte Carlo code, MCNP4B was applied for voxel Monte Carlo calculation. Simple binary voxel phantom and combinatorial geometry phantom composed of two materials were constructed for validating the voxel Monte Carlo calculation system. The tomographic images of VHP man provided by NLM(National Library of Medicine) were segmented and indexed to construct voxel head phantom. Comparison od doses for broad parallel gamma and neutron beams in AP and PA directions showed decrease of brain dose due to the attenuation of neutron in eye balls in case of voxel head phantom. The spherical tumor volume with diameter, 5cm was defined in the center of brain for BNCT dose calculation in which accurate 3 dimensional dose calculation is essential. As a result of BNCT dose calculation for downward neutron beam of 10keV and 40keV, the tumor dose is about doubled when boron concentration ratio between the tumor to the normal tissue is 30{mu}g/g to 3 {mu}g/g. This study established the voxel Monte Carlo calculation system and suggested the feasibility of precise dose calculation in therapeutic radiology.

  14. Dosimetric study on head CT scans using adult and newborn phantoms

    International Nuclear Information System (INIS)

    Paiva de O, G. A.; Prata M, A.

    2016-10-01

    Computed tomography is the radiodiagnostic method that most contributes to the dose deposition in population. Therefore, the dose reductions used in these tests are very important, especially for pediatric patients who have a life expectancy greater than the rest of the population. This study purpose to compare the doses generated from newborns compared to adult patients in head computed tomography scans. Two head phantoms in a cylindrical shape made in PMMA were used, one to adult and another to newborn patient dimensions. The pediatric routine scan protocol from a radiological service was used for the computed tomography scans. They were performed in General Electric Computed Tomography scanner, Bright Speed model with 4 channels. The absorbed dose measurements were performed with a pencil chamber placed into both phantoms. The newborn head phantom was developed in order to compare the amount of absorbed dose by the phantoms when it is used the same acquisition protocol. The dose found for newborn phantom was 29.9% higher than the adult phantom. (Author)

  15. Mathematical human phantoms and their application to radiation protection

    International Nuclear Information System (INIS)

    Yamaguchi, Yasuhiro

    1998-01-01

    This review described the characteristics of mathematical phantoms, their history over 30 years and their application. Mathematical phantoms are classified into two models of formula and voxel types. In the former, human body and organs are described by 2- and/or 3-D mathematical formula and can be seen as a combination of solid bodies like spheres, cubes and ovals. The phantom is composed from three tissue components (bone, lung and soft tissue) and made on data on Reference Man in ICRP Publ. 23. The latter voxel (volume pixel) phantom consists from a number of small cubes based on CT and MRI images of a certain man. For instance, the phantom CHILD, 1.54 x 1.54 x 8.00 mm 3 in size, is based on a 7-year old child, which consisting from about one million voxels. The mathematical phantom was first made in Oak Ridge National Laboratory in the middle of the nineteen-sixties, which have undergone various improvements to reach MIRD-5 phantom. Thereafter, many similitude phantoms have been made as a variation of MIRD-5, depending on age and sex (e.g., ADAM and EVA). Voxel phantom was made in the middle of nineteen-eighties and have undergone improvements which are continued even currently in Japan, U.S. etc. The mathematical phantoms are used for calculation of radiation transport program by Monte Carlo method in the field of radiation protection. Also in the field of medicine, the phantom is used for calculation of internal and external exposure doses, of correction constants of externally measuring instruments, of doses for neutron capture therapy and of A-bomb exposure doses in Hiroshima and Nagasaki for reevaluation. Recently, the development of phantom is in the current from formula phantom to voxel one due to the purpose of precision and standardization. (K.H.)

  16. A deformable head and neck phantom with in-vivo dosimetry for adaptive radiotherapy quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Graves, Yan Jiang [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 and Department of Physics, University of California San Diego, La Jolla, California 92093 (United States); Smith, Arthur-Allen; Mcilvena, David; Manilay, Zherrina; Lai, Yuet Kong [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States); Rice, Roger; Mell, Loren; Cerviño, Laura, E-mail: lcervino@ucsd.edu, E-mail: steve.jiang@utsouthwestern.edu [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 (United States); Jia, Xun; Jiang, Steve B., E-mail: lcervino@ucsd.edu, E-mail: steve.jiang@utsouthwestern.edu [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75235 (United States)

    2015-04-15

    Purpose: Patients’ interfractional anatomic changes can compromise the initial treatment plan quality. To overcome this issue, adaptive radiotherapy (ART) has been introduced. Deformable image registration (DIR) is an important tool for ART and several deformable phantoms have been built to evaluate the algorithms’ accuracy. However, there is a lack of deformable phantoms that can also provide dosimetric information to verify the accuracy of the whole ART process. The goal of this work is to design and construct a deformable head and neck (HN) ART quality assurance (QA) phantom with in vivo dosimetry. Methods: An axial slice of a HN patient is taken as a model for the phantom construction. Six anatomic materials are considered, with HU numbers similar to a real patient. A filled balloon inside the phantom tissue is inserted to simulate tumor. Deflation of the balloon simulates tumor shrinkage. Nonradiopaque surface markers, which do not influence DIR algorithms, provide the deformation ground truth. Fixed and movable holders are built in the phantom to hold a diode for dosimetric measurements. Results: The measured deformations at the surface marker positions can be compared with deformations calculated by a DIR algorithm to evaluate its accuracy. In this study, the authors selected a Demons algorithm as a DIR algorithm example for demonstration purposes. The average error magnitude is 2.1 mm. The point dose measurements from the in vivo diode dosimeters show a good agreement with the calculated doses from the treatment planning system with a maximum difference of 3.1% of prescription dose, when the treatment plans are delivered to the phantom with original or deformed geometry. Conclusions: In this study, the authors have presented the functionality of this deformable HN phantom for testing the accuracy of DIR algorithms and verifying the ART dosimetric accuracy. The authors’ experiments demonstrate the feasibility of this phantom serving as an end

  17. Study of the CT peripheral dose variation in a head phantom

    International Nuclear Information System (INIS)

    Mourao, Arnaldo P.

    2009-01-01

    The computed tomography is frequently used for the brain diagnosis and it is responsible for the largest doses in the head among the X-ray examinations. Established indexes define a reference dose value for a scan routine; however the dose value has a longitudinal variation in the scan. The purpose of this study is to investigate the variation of the peripheral doses in the head scan using a polymethylmethacrylate head phantom. The studies were performed using two different computed tomography scanners in the option single slice with a routine of a head adult protocol (i.e. default protocol in the scanner software). Radiation doses were measured using thermoluminescent dosimeter (LiF - TLD) rod model, distributed inside the PMMA head phantom in periphery and central area. The results allowed registering the variation dose curve, longitudinally the scan, for the peripheral area and to determine the MSAD value. The peripheral maximum dose value measured can be compared with the maximum dose value in the center of the phantom in each different routine (author)

  18. 3D dose distribution calculation in a voxelized human phantom by means of Monte Carlo method

    International Nuclear Information System (INIS)

    Abella, V.; Miro, R.; Juste, B.; Verdu, G.

    2010-01-01

    The aim of this work is to provide the reconstruction of a real human voxelized phantom by means of a MatLab program and the simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) 60 Co radiotherapy unit, by using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project results in 3D dose mapping calculations inside the voxelized antropomorphic head phantom. The program provides the voxelization by first processing the CT slices; the process follows a two-dimensional pixel and material identification algorithm on each slice and three-dimensional interpolation in order to describe the phantom geometry via small cubic cells, resulting in an MCNP input deck format output. Dose rates are calculated by using the MCNP5 tool FMESH, superimposed mesh tally, which gives the track length estimation of the particle flux in units of particles/cm 2 . Furthermore, the particle flux is converted into dose by using the conversion coefficients extracted from the NIST Physical Reference Data. The voxelization using a three-dimensional interpolation technique in combination with the use of the FMESH tool of the MCNP Monte Carlo code offers an optimal simulation which results in 3D dose mapping calculations inside anthropomorphic phantoms. This tool is very useful in radiation treatment assessments, in which voxelized phantoms are widely utilized.

  19. Advances in development of young-pediatric anthropometric and anthropomorphic head and neck phantoms for dosimetry

    International Nuclear Information System (INIS)

    Thompson, Larissa; Campos, Tarcisio P.R.

    2005-01-01

    The neck malign cancer in pediatric population differs significantly than adult cancer. The pediatric primary malign tumors result in the neck and head fence 5% . The malign cervical tumors, generally, are rabdomyossarcoms and lymphomas. The least frequent malign cancer includes metastasis, scammous cells and thyroid cancer. The larynx cancer treatment is surgery, preferentially. However, lesions with little infiltration, that do not compromise the vocals cords mobile, do not infiltrate cartilage, and do not compromise neither the anterior comissure neither the arytenoid, can be controlled with exclusive radiotherapy. The traditional dose for sub-clinical disease in larynx cancer, neck and head region, has been 50 to 60 Gy to standard fraction of 2 Gy/day, five times for week. When the treatment is consummated with exclusive radiotherapy in primary tumor. The dose must be higher, diversifying from 66 (for small tumors T1) to 70 Gy (for higher tumors, that T2 or T3). Phantoms are simulators utilized for dose prediction in patient simulating radiation interactions with matter. Also it is applied for radio diagnosis equipment calibration and quality control of medical image. Many kind of phantoms are developed, handmade and commercialized, with matters and forms most varied, holding distinct purpose, in senses of establishing double check parameters for reducing planning and calibration errors. This study addresses the development of a object for simulating young-pediatric anthropometric and anthropomorphic head and neck, called phantom, for dosimetric studies. The methodology will be based on the preparation of a phantom respecting the anatomic standards and its tissue equivalent composition. The hope is that phantom can be used in the scientific researches of radiation protocols applied to young-pediatric patient. (author)

  20. Radiological response and dosimetry in physical phantom of head and neck for 3D conformational radiotherapy; Resposta radiologica e dosimetria em phantom fisico de cabeca e pescoco para radioterapia conformacional 3D

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Larissa

    2013-07-01

    Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film

  1. Simulation tools for two-dimensional experiments in x-ray computed tomography using the FORBILD head phantom.

    Science.gov (United States)

    Yu, Zhicong; Noo, Frédéric; Dennerlein, Frank; Wunderlich, Adam; Lauritsch, Günter; Hornegger, Joachim

    2012-07-07

    Mathematical phantoms are essential for the development and early stage evaluation of image reconstruction algorithms in x-ray computed tomography (CT). This note offers tools for computer simulations using a two-dimensional (2D) phantom that models the central axial slice through the FORBILD head phantom. Introduced in 1999, in response to a need for a more robust test, the FORBILD head phantom is now seen by many as the gold standard. However, the simple Shepp-Logan phantom is still heavily used by researchers working on 2D image reconstruction. Universal acceptance of the FORBILD head phantom may have been prevented by its significantly higher complexity: software that allows computer simulations with the Shepp-Logan phantom is not readily applicable to the FORBILD head phantom. The tools offered here address this problem. They are designed for use with Matlab®, as well as open-source variants, such as FreeMat and Octave, which are all widely used in both academia and industry. To get started, the interested user can simply copy and paste the codes from this PDF document into Matlab® M-files.

  2. Simulation tools for two-dimensional experiments in x-ray computed tomography using the FORBILD head phantom

    International Nuclear Information System (INIS)

    Yu Zhicong; Noo, Frédéric; Wunderlich, Adam; Dennerlein, Frank; Lauritsch, Günter; Hornegger, Joachim

    2012-01-01

    Mathematical phantoms are essential for the development and early stage evaluation of image reconstruction algorithms in x-ray computed tomography (CT). This note offers tools for computer simulations using a two-dimensional (2D) phantom that models the central axial slice through the FORBILD head phantom. Introduced in 1999, in response to a need for a more robust test, the FORBILD head phantom is now seen by many as the gold standard. However, the simple Shepp–Logan phantom is still heavily used by researchers working on 2D image reconstruction. Universal acceptance of the FORBILD head phantom may have been prevented by its significantly higher complexity: software that allows computer simulations with the Shepp–Logan phantom is not readily applicable to the FORBILD head phantom. The tools offered here address this problem. They are designed for use with Matlab®, as well as open-source variants, such as FreeMat and Octave, which are all widely used in both academia and industry. To get started, the interested user can simply copy and paste the codes from this PDF document into Matlab® M-files. (note)

  3. Measurement of hard tissue density of head phantom based on the HU by using CBCT

    International Nuclear Information System (INIS)

    Kim, Moon Sun; Kang, Dong Wan; Kim, Jae Duk

    2009-01-01

    The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density (g cm -3 ) obtained from cone-beam computed tomography (CBMercuRay TM ) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the CBMercuRay TM (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using CBWorks TM . Linear regression analysis and Student t-test were performed statistically. There was no significant difference (P>0.54) between real densities and measured densities. A linear regression was performed using the density, ρ (g cm -3 ), as the dependent variable in terms of the HU (H). The regression equation obtained was ρ=0.00072 H-0.01588 with an R2 value of 0.9968. Density values based on the Hounsfield scale was 1697.1 ± 24.9 HU in cortical bone, 526.5 ± 44.4 HU in trabecular bone, 2639.1 ± 48.7 HU in enamel, 1246.1 ± 39.4 HU in dentin of dental head phantom. CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

  4. Development and application of anthropomorphic voxel phantom of the head for in vivo measurement.

    Science.gov (United States)

    Vrba, T

    2007-01-01

    The in vivo measurement of the activity deposited in the skeleton is a very useful source of information on human internal contaminations with transuranic elements, e.g. americium 241, especially for long time periods after intake. Measurements are performed on the skull or the larger joints such as the knee or elbow. The paper deals with the construction of an anthropomorphic numerical phantom based on CT scans, its potential for calibration and the estimation of the uncertainties of the detection system. The density of bones, activity distribution and position of the detectors were changed in individual simulations in order to estimate their effects on the result of the measurement. The results from simulations with the numerical phantom were compared with the results of physical phantoms.

  5. The role of phantom and treatment head generated bremsstrahlung in high-energy electron beam dosimetry

    International Nuclear Information System (INIS)

    Sorcini, B.B.; Hyoedynmaa, S.; Brahme, A.

    1996-01-01

    An analytical expression has been derived for the phantom generated bremsstrahlung photons in plane-parallel monoenergetic electron beams normally incident on material of any atomic number (Be, H 2 O, Al, Cu and U). The expression is suitable for the energy range from 1 to 50 MeV and it is solely based on known scattering power and radiative and collision stopping power data for the material at the incident electron energy. The depth dose distribution due to the bremsstrahlung generated by the electrons in the phantom is derived by convolving the bremsstrahlung energy fluence produced in the phantom with a simple analytical energy deposition kernel. The kernel accounts for both electrons and photons set in motion by the bremsstrahlung photons. The energy loss by the primary electrons, the build-up of the electron fluence and the generation, attenuation and absorption of bremsstrahlung photons are all taken into account in the analytical formula. The longitudinal energy deposition kernel is derived analytically and it is consistent with both the classical biexponential relation describing the photon depth dose distribution and the exponential attenuation of the primary photons. For comparison Monte Carlo calculated energy deposition distributions using ITS3 code were used. Good agreement was found between the results with the analytical expression and the Monte Carlo calculation. For tissue equivalent materials, the maximum total energy deposition differs by less than 0.2% from Monte Carlo calculated dose distributions. The result can be used to estimate the depth dependence of phantom generated bremsstrahlung in different materials in therapeutic electron beams and the bremsstrahlung production in different electron absorbers such as scattering foils, transmission monitors and photon and electron collimators. By subtracting the phantom generated bremsstrahlung from the total bremsstrahlung background the photon contamination generated in the treatment head can be

  6. Linear versus circular polarization of head coils - comparison on phantom and in the clinic

    International Nuclear Information System (INIS)

    Schratter, M.; Kramer, J.; Prayer, L.; Wimberger, D.; Imhof, H.; Schmid, W.

    1990-01-01

    Two different head coils - one with linear polarization and the other with circular polarization - were compared under the same measurement conditions. Comparison was done on a phantom with waterfilled and gadolinium-filled pin-holes, as well as on anatomical MR images of 23 volunteers. In three volunteers the whole brain was examined while, in the remaining 20 volunteers the sella region or cerebellopontine angleregion was examined. Criteria for comparison were signal-to-noise ratio, background noise, and detail resolution (phantom), as well as subjective criteria - image sharpness, anatomical, contrast, and recognition of anatomical details -, evaluated on anatomical MR images by four radiologists independently of each other. The results show a significant improvement of signal-to-noise ratio, lower background noise and therefore marked improvement of images harpness, and moderate improvement in the recognition of anatomical details using the circular polarized head coil; as for as detail resolution and anatomical contrast were concerned, however, no significant difference was seen between the two coils. Major advantages of the circular, polarized head coil in clinical application are shorter measurement times (reduced number of acquisitions), as well as thinner slices without loss of signal-to-noise ratio. (orig.) [de

  7. Human torso phantom for imaging of heart with realistic modes of cardiac and respiratory motion

    Science.gov (United States)

    Boutchko, Rostyslav; Balakrishnan, Karthikayan; Gullberg, Grant T; O& #x27; Neil, James P

    2013-09-17

    A human torso phantom and its construction, wherein the phantom mimics respiratory and cardiac cycles in a human allowing acquisition of medical imaging data under conditions simulating patient cardiac and respiratory motion.

  8. Large scale study on the variation of RF energy absorption in the head and brain regions of adults and children and evaluation of the SAM phantom conservativeness

    International Nuclear Information System (INIS)

    Keshvari, J; Kivento, M; Christ, A; Bit-Babik, G

    2016-01-01

    This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases. (paper)

  9. Large scale study on the variation of RF energy absorption in the head & brain regions of adults and children and evaluation of the SAM phantom conservativeness

    Science.gov (United States)

    Keshvari, J.; Kivento, M.; Christ, A.; Bit-Babik, G.

    2016-04-01

    This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases.

  10. Development and application of a pediatric head phantom for dosimetry in computed tomography; Desenvolvimento e aplicacao de um simulador pediatrico craniano para dosimetria em tomografia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Elaine Wirney

    2016-11-01

    To determine the exposure levels and the absorbed dose in patients undergoing CT scans, is necessary to calculate the CT dose index in measurements with a PMMA or water phantom. The phantom must be enough to simulate the attenuation and scattering characteristics of a human body or parts in a radiation field. The CT specific quantities : CT air kerma index (Ca,100) , weighted CT air kerma index (CW ), a total volume CT air kerma index (Cvol) and the CT air kerma-length product (PKL) must be determined and compared to literature reference levels. In this work a head pediatric phantom was developed, considering that the Brazilian published Diagnostic Reference Levels (DRL) are based on adult phantom measurements. This developed phantom shows a construction innovation using materials to simulate the skullcap, cortical bone (aluminum) and cancellous bone (PVC), and it was filled with distilled water. The phantom dimension follows the recommendations of the World Health Organization and the International Commission on Radiation Units for children from 0 to 5 years old head size: diameter of 160 mm and height of 155 mm. The skullcap has 4 mm of thickness and 111.9 mm of internal diameter. In order to evaluate its behavior, tests were carried out in calibration laboratories and in clinical beams. The results showed attenuation up to 23% when different materials are used as skullcap, demonstrating that the DRLs adopted could be overestimating the dose received by pediatric patients. It is observed that the dose received by CT skull scans presents different distribution, due to the skullcap partially attenuation and/or backscattering which is not considered when the PMMA phantom is used.

  11. A digital phantom of the axilla based on the Visible Human Project data set

    Science.gov (United States)

    McCallum, S. J.; Welch, A. E.; Baker, L.

    2001-08-01

    In this paper, we describe the development of a new digital phantom designed for Monte Carlo simulations of breast cancer and particularly positron emission tomography (PET) imaging of the axillary lymph nodes. The phantom was based on data from the Visible Human Project female data set. The phantom covers the head-to-diaphragm regions; 17 major tissue types were segmented and 66 individual lymph nodes were identified. The authors have used the phantom in Monte Carlo simulations to model a reduced field-of-view PET imager based on two flat plate arrays placed on either side of the shoulder. Images used a simple single angle set of projections. The authors have conducted two preliminary studies: one modeling a single-frame PET acquisition 60 min after FDG injection and the other modeling a dynamic PET acquisition simulating four time frames after FDG injection. The dynamic results were processed into parametric images using the Patlak method and show the advantage to be gained by including the temporal information for legion detection. The authors' preliminary results indicate that the performance of such an imager forming projection images is not sufficient for axillary node PET imaging.

  12. An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy

    International Nuclear Information System (INIS)

    Gallas, Raya R.; Huenemohr, Nora; Runz, Armin; Niebuhr, Nina I.; Greilich, Steffen; Jaekel, Oliver

    2015-01-01

    With the increasing complexity of external beam therapy ''end-to-end'' tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification.

  13. An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gallas, Raya R.; Huenemohr, Nora; Runz, Armin; Niebuhr, Nina I.; Greilich, Steffen [German Cancer Research Center (DKFZ), Heidelberg (Germany). Div. of Medical Physics in Radiation Oncology; National Center for Radiation Research in Oncology, Heidelberg (Germany). Heidelberg Institute of Radiation Oncology (HIRO); Jaekel, Oliver [German Cancer Research Center (DKFZ), Heidelberg (Germany). Div. of Medical Physics in Radiation Oncology; National Center for Radiation Research in Oncology, Heidelberg (Germany). Heidelberg Institute of Radiation Oncology (HIRO); Heidelberg University Hospital (Germany). Dept. of Radiation Oncology; Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg (Germany)

    2015-07-01

    With the increasing complexity of external beam therapy ''end-to-end'' tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification.

  14. An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy.

    Science.gov (United States)

    Gallas, Raya R; Hünemohr, Nora; Runz, Armin; Niebuhr, Nina I; Jäkel, Oliver; Greilich, Steffen

    2015-12-01

    With the increasing complexity of external beam therapy "end-to-end" tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification. Copyright © 2015. Published by Elsevier GmbH.

  15. Effect of titanium dental implants on proton therapy delivered for head tumors: experimental validation using an anthropomorphic head phantom

    Science.gov (United States)

    Oancea, C.; Shipulin, K.; Mytsin, G.; Molokanov, A.; Niculae, D.; Ambrožová, I.; Davídková, M.

    2017-03-01

    A dosimetric experiment was performed at the Medico-Technical Complex in the Joint Institute for Nuclear Research, Dubna, to investigate the effects of metallic dental implants in the treatment of head and neck tumours with proton therapy. The goal of the study was to evaluate the 2D dose distributions of different clinical treatment plans measured in an anthropomorphic phantom, and compare them to predictions from a treatment planning system. The anthropomorphic phantom was sliced into horizontal segments. Two grade 4 Titanium implants were inserted between 2 slices, corresponding to a maxillary area. GafChromic EBT2 films were placed between the segments containing the implants to measure the 2D delivered dose. Two different targets were designed: the first target includes the dental implants in the isocentre, and in the second target, the proton beam is delivered through the implants, which are located at the entrance region of the Bragg curve. The experimental results were compared to the treatment plans made using our custom 3D Treatment Planning System, named RayTreat. To quantitatively determine differences in the isodose distributions (measured and calculated), the gamma index (3 mm, 3%) was calculated for each target for the matrix value in the region of high isodose (> 90%): for the experimental setup, which includes the implants in the SOBP region, the result obtained was 84.3%. When the implants were localised in the entrance region of the Bragg curve, the result obtained was 86.4%. In conclusion, the uncertainties introduced by the clinically planned dose distribution are beyond reasonable limits. The linear energy transfer spectra in close proximity to the implants were investigated using solid state nuclear track detectors (TED). Scattered particles outside the target were detected.

  16. Effect of titanium dental implants on proton therapy delivered for head tumors: experimental validation using an anthropomorphic head phantom

    International Nuclear Information System (INIS)

    Oancea, C.; Shipulin, K.; Mytsin, G.; Molokanov, A.; Niculae, D.; Ambrožová, I.; Davídková, M.

    2017-01-01

    A dosimetric experiment was performed at the Medico-Technical Complex in the Joint Institute for Nuclear Research, Dubna, to investigate the effects of metallic dental implants in the treatment of head and neck tumours with proton therapy. The goal of the study was to evaluate the 2D dose distributions of different clinical treatment plans measured in an anthropomorphic phantom, and compare them to predictions from a treatment planning system. The anthropomorphic phantom was sliced into horizontal segments. Two grade 4 Titanium implants were inserted between 2 slices, corresponding to a maxillary area. GafChromic EBT2 films were placed between the segments containing the implants to measure the 2D delivered dose. Two different targets were designed: the first target includes the dental implants in the isocentre, and in the second target, the proton beam is delivered through the implants, which are located at the entrance region of the Bragg curve. The experimental results were compared to the treatment plans made using our custom 3D Treatment Planning System, named RayTreat. To quantitatively determine differences in the isodose distributions (measured and calculated), the gamma index (3 mm, 3%) was calculated for each target for the matrix value in the region of high isodose (> 90%): for the experimental setup, which includes the implants in the SOBP region, the result obtained was 84.3%. When the implants were localised in the entrance region of the Bragg curve, the result obtained was 86.4%. In conclusion, the uncertainties introduced by the clinically planned dose distribution are beyond reasonable limits. The linear energy transfer spectra in close proximity to the implants were investigated using solid state nuclear track detectors (TED). Scattered particles outside the target were detected.

  17. Code system to compute radiation dose in human phantoms

    International Nuclear Information System (INIS)

    Ryman, J.C.; Cristy, M.; Eckerman, K.F.; Davis, J.L.; Tang, J.S.; Kerr, G.D.

    1986-01-01

    Monte Carlo photon transport code and a code using Monte Carlo integration of a point kernel have been revised to incorporate human phantom models for an adult female, juveniles of various ages, and a pregnant female at the end of the first trimester of pregnancy, in addition to the adult male used earlier. An analysis code has been developed for deriving recommended values of specific absorbed fractions of photon energy. The computer code system and calculational method are described, emphasizing recent improvements in methods

  18. Evaluation of radiation dose in pediatric head CT examination: a phantom study

    Science.gov (United States)

    Norhasrina Nik Din, Nik; Zainon, Rafidah; Rahman, Ahmad Taufek Abdul

    2018-01-01

    The aim of this study was to evaluate the radiation dose in pediatric head Computed Tomography examination. It was reported that decreasing tube voltage in CT examination can reduce the dose to patients significantly. A head phantom was scanned with dual-energy CT at 80 kV and 120 kV. The tube current was set using automatic exposure control mode and manual setting. The pitch was adjusted to 1.4, 1.45 and 1.5 while the slice thickness was set at 5 mm. The dose was measured based on CT Dose Index (CTDI). Results from this study have shown that the image noise increases substantially with low tube voltage. The average dose was 2.60 mGy at CT imaging parameters of 80 kV and 10 - 30 mAs. The dose increases up to 17.19 mGy when the CT tube voltage increases to 120 kV. With the reduction of tube voltage from 120 kV to 80 kV, the radiation dose can be reduced by 12.1% to 15.1% without degradation of contrast-to-noise ratio.

  19. Marvin: an anatomical phantom for dosimetric evaluation of complex radiotherapy of the head and neck

    Science.gov (United States)

    Aitkenhead, A. H.; Rowbottom, C. G.; Mackay, R. I.

    2013-10-01

    We report on the design of Marvin, a Model Anatomy for Radiotherapy Verification and audit In the head and Neck and present results demonstrating its use in the development of the Elekta volumetric modulated arc therapy (VMAT) technique at the Christie, and in the audit of TomoTherapy and Varian RapidArc at other institutions. The geometry of Marvin was generated from CT datasets of eight male and female patients lying in the treatment position, with removable inhomogeneities modelling the sinuses and mandible. A modular system allows the phantom to be used with a range of detectors, with the locations of the modules being based on an analysis of a range of typical treatment plans (27 in total) which were mapped onto the phantom geometry. Results demonstrate the use of Gafchromic EBT2/EBT3 film for measurement of relative dose in a plane through the target and organs-at-risk, and the use of a small-volume ionization chamber for measurement of absolute dose in the target and spinal cord. Measurements made during the development of the head and neck VMAT protocol at the Christie quantified the improvement in plan delivery resulting from the installation of the Elekta Integrity upgrade (which permits an effectively continuously variable dose rate), with plans delivered before and after the upgrade having 88.5 ± 9.4% and 98.0 ± 2.2% respectively of points passing a gamma analysis (at 4%, 4 mm, global). Audits of TomoTherapy and Varian RapidArc neck techniques at other institutions showed a similar quality of plan delivery as for post-Integrity Elekta VMAT: film measurements for both techniques had >99% of points passing a gamma analysis at the clinical criteria of 4%, 4 mm, global, and >95% of points passing at tighter criteria of 3%, 3 mm, global; and absolute dose measurements in the PTV and spinal cord were within 1.5% and 3.5% of the planned doses respectively for both techniques. The results demonstrate that Marvin is an efficient and effective means of

  20. Marvin: an anatomical phantom for dosimetric evaluation of complex radiotherapy of the head and neck

    International Nuclear Information System (INIS)

    Aitkenhead, A H; Rowbottom, C G; Mackay, R I

    2013-01-01

    We report on the design of Marvin, a Model Anatomy for Radiotherapy Verification and audit In the head and Neck and present results demonstrating its use in the development of the Elekta volumetric modulated arc therapy (VMAT) technique at the Christie, and in the audit of TomoTherapy and Varian RapidArc at other institutions. The geometry of Marvin was generated from CT datasets of eight male and female patients lying in the treatment position, with removable inhomogeneities modelling the sinuses and mandible. A modular system allows the phantom to be used with a range of detectors, with the locations of the modules being based on an analysis of a range of typical treatment plans (27 in total) which were mapped onto the phantom geometry. Results demonstrate the use of Gafchromic EBT2/EBT3 film for measurement of relative dose in a plane through the target and organs-at-risk, and the use of a small-volume ionization chamber for measurement of absolute dose in the target and spinal cord. Measurements made during the development of the head and neck VMAT protocol at the Christie quantified the improvement in plan delivery resulting from the installation of the Elekta Integrity upgrade (which permits an effectively continuously variable dose rate), with plans delivered before and after the upgrade having 88.5 ± 9.4% and 98.0 ± 2.2% respectively of points passing a gamma analysis (at 4%, 4 mm, global). Audits of TomoTherapy and Varian RapidArc neck techniques at other institutions showed a similar quality of plan delivery as for post-Integrity Elekta VMAT: film measurements for both techniques had >99% of points passing a gamma analysis at the clinical criteria of 4%, 4 mm, global, and >95% of points passing at tighter criteria of 3%, 3 mm, global; and absolute dose measurements in the PTV and spinal cord were within 1.5% and 3.5% of the planned doses respectively for both techniques. The results demonstrate that Marvin is an efficient and effective means of

  1. CT head-scan dosimetry in an anthropomorphic phantom and associated measurement of ACR accreditation-phantom imaging metrics under clinically representative scan conditions

    Energy Technology Data Exchange (ETDEWEB)

    Brunner, Claudia C.; Stern, Stanley H.; Chakrabarti, Kish [U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States); Minniti, Ronaldo [National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899 (United States); Parry, Marie I. [Walter Reed National Military Medical Center, 8901 Rockville Pike, Bethesda, Maryland 20889 (United States); Skopec, Marlene [National Institutes of Health, 9000 Rockville Pike, Bethesda, Maryland 20892 (United States)

    2013-08-15

    Purpose: To measure radiation absorbed dose and its distribution in an anthropomorphic head phantom under clinically representative scan conditions in three widely used computed tomography (CT) scanners, and to relate those dose values to metrics such as high-contrast resolution, noise, and contrast-to-noise ratio (CNR) in the American College of Radiology CT accreditation phantom.Methods: By inserting optically stimulated luminescence dosimeters (OSLDs) in the head of an anthropomorphic phantom specially developed for CT dosimetry (University of Florida, Gainesville), we measured dose with three commonly used scanners (GE Discovery CT750 HD, Siemens Definition, Philips Brilliance 64) at two different clinical sites (Walter Reed National Military Medical Center, National Institutes of Health). The scanners were set to operate with the same data-acquisition and image-reconstruction protocols as used clinically for typical head scans, respective of the practices of each facility for each scanner. We also analyzed images of the ACR CT accreditation phantom with the corresponding protocols. While the Siemens Definition and the Philips Brilliance protocols utilized only conventional, filtered back-projection (FBP) image-reconstruction methods, the GE Discovery also employed its particular version of an adaptive statistical iterative reconstruction (ASIR) algorithm that can be blended in desired proportions with the FBP algorithm. We did an objective image-metrics analysis evaluating the modulation transfer function (MTF), noise power spectrum (NPS), and CNR for images reconstructed with FBP. For images reconstructed with ASIR, we only analyzed the CNR, since MTF and NPS results are expected to depend on the object for iterative reconstruction algorithms.Results: The OSLD measurements showed that the Siemens Definition and the Philips Brilliance scanners (located at two different clinical facilities) yield average absorbed doses in tissue of 42.6 and 43.1 m

  2. Radiological image interpretation for hematoma and small tumors simulated in a head and neck phantom

    International Nuclear Information System (INIS)

    Thompson, Larissa; Campos, Tarcisio Passos Ribeiro

    2009-01-01

    Subarachnoidal hemorrhages (HSA) are caused by aneurysms and their symptom usually becomes evident after a rupture. Nevertheless, there are situations in which the aneurysms compress a nerve or produce a bleed before the rupture happens, as consequence one alert signal like headache occurs. It, often occurs after minutes or weeks previous the major rupture. The main goal is to prevent a massive hemorrhage. Thus the Computer Tomography (CT) scan of skull provides a basic and specific function: to reveal the position where the hemorrhage was produced, guiding to a additional medical procedures. On the other hand, CT does not prevent the cerebral tumor development, but precise diagnostic for some symptoms such as vomits, nauseas, epileptic attacks, weakness in arms or legs, require this image protocol. CT has its fundamental importance to tumor detection. Indeed CT reveals its importance in the tumor early diagnosis. Specialized training in CT analysis shall be done. Ahead of a precise diagnosis to manager an early intervention, a CT diagnostic training is suitable for a favorable prognostic. In this context, focusing on propose of radiological inquires; a head and neck phantom will be used to simulate hematomas and cerebral tumors. Images of CT of skull will be used to identify these lesions physically implanted in phantom. The radiological response will be analyzed with the purpose of validation of the skull's CT diagnosis, for a double blind test. The diagnostic with non contrast CT shows only higher 5mm diameter subjects (tumors) identified by the double blind test. Hemorrhage is identified by only the administrator (single-blind test). As conclusion, the author's launches the hypothesis that this object simulator shall provide assistance for specialized training on pathology interpretation on radiological images. (author)

  3. A virtual phantom library for the quantification of deformable image registration uncertainties in patients with cancers of the head and neck.

    Science.gov (United States)

    Pukala, Jason; Meeks, Sanford L; Staton, Robert J; Bova, Frank J; Mañon, Rafael R; Langen, Katja M

    2013-11-01

    Deformable image registration (DIR) is being used increasingly in various clinical applications. However, the underlying uncertainties of DIR are not well-understood and a comprehensive methodology has not been developed for assessing a range of interfraction anatomic changes during head and neck cancer radiotherapy. This study describes the development of a library of clinically relevant virtual phantoms for the purpose of aiding clinicians in the QA of DIR software. These phantoms will also be available to the community for the independent study and comparison of other DIR algorithms and processes. Each phantom was derived from a pair of kVCT volumetric image sets. The first images were acquired of head and neck cancer patients prior to the start-of-treatment and the second were acquired near the end-of-treatment. A research algorithm was used to autosegment and deform the start-of-treatment (SOT) images according to a biomechanical model. This algorithm allowed the user to adjust the head position, mandible position, and weight loss in the neck region of the SOT images to resemble the end-of-treatment (EOT) images. A human-guided thin-plate splines algorithm was then used to iteratively apply further deformations to the images with the objective of matching the EOT anatomy as closely as possible. The deformations from each algorithm were combined into a single deformation vector field (DVF) and a simulated end-of-treatment (SEOT) image dataset was generated from that DVF. Artificial noise was added to the SEOT images and these images, along with the original SOT images, created a virtual phantom where the underlying "ground-truth" DVF is known. Images from ten patients were deformed in this fashion to create ten clinically relevant virtual phantoms. The virtual phantoms were evaluated to identify unrealistic DVFs using the normalized cross correlation (NCC) and the determinant of the Jacobian matrix. A commercial deformation algorithm was applied to the virtual

  4. Electromagnetic Head-And-Neck Hyperthermia Applicator: Experimental Phantom Verification and FDTD Model

    International Nuclear Information System (INIS)

    Paulides, Margarethus M.; Bakker, Jurriaan F.; Rhoon, Gerard C. van

    2007-01-01

    Purpose: To experimentally verify the feasibility of focused heating in the neck region by an array of two rings of six electromagnetic antennas. We also measured the dynamic specific absorption rate (SAR) steering possibilities of this setup and compared these SAR patterns to simulations. Methods and Materials: Using a specially constructed laboratory prototype head-and-neck applicator, including a neck-mimicking cylindrical muscle phantom, we performed SAR measurements by electric field, Schottky-diode sheet measurements and, using the power-pulse technique, by fiberoptic thermometry and infrared thermography. Using phase steering, we also steered the SAR distribution in radial and axial directions. All measured distributions were compared with the predictions by a finite-difference time-domain-based electromagnetic simulator. Results: A central 50% iso-SAR focus of 35 ± 3 mm in diameter and about 100 ± 15 mm in length was obtained for all investigated settings. Furthermore, this SAR focus could be steered toward the desired location in the radial and axial directions with an accuracy of ∼5 mm. The SAR distributions as measured by all three experimental methods were well predicted by the simulations. Conclusion: The results of our study have shown that focused heating in the neck is feasible and that this focus can be effectively steered in the radial and axial directions. For quality assurance measurements, we believe that the Schottky-diode sheet provides the best compromise among effort, speed, and accuracy, although a more specific and improved design is warranted

  5. Validation of a cylindrical phantom for verification of radiotherapy treatments in head and neck with special techniques

    International Nuclear Information System (INIS)

    Vargas, Nicolas M.; Garcia, Marcia; Piriz, Gustavo; Perez, Niurka

    2011-01-01

    Verification of radiotherapy treatments in head and neck requires, among other things, small volume chambers and a phantom to reproduce the geometry and density of the anatomical structure. New documents from the ICRU (International Commission on Radiation Units and Measurements), Report 83, established the need for quality control in radiotherapy with special techniques such as IMRT (intensity-modulated radiation therapy). In this study, we built a cylindrical acrylic phantom with standing water, containing seven measuring points in the transverse plane and free location (0-20 cm) in the longitudinal plane. These points of measurement are constituted by cavities for the accommodation of the ionization chamber of 7 mm of mayor diameter (semi flex, pinpoint with build cup). The results of the phantom validation yielded percentage differences less than 1% in fixed beams and less than 2.5% in arc therapy for TPS Eclipse calculation. The preparation of this phantom, particularly made to verify the head and neck treatments, was simple and reliable for checking the dose in radiotherapy with fixed beams and/or special techniques such as arc therapy or IMRT, so that will be sent to various radiotherapy centers in the country for dosimetric verification in such treatments. (author)

  6. Validation of a cylindrical phantom for verification of radiotherapy treatments in head and neck with special techniques

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Nicolas M.; Garcia, Marcia, E-mail: nimoralesv@gmail.com [Universidad de La Frontera, Temuco (Chile). Dept. de Ciencias Fisicas; Piriz, Gustavo [Instituto Nacional del Cancer, Santiago (Chile). Fisica Medica; Perez, Niurka [Instituto de Salud Publica, Santiago (Chile). QA Radioterapia. Inst. de Salud Publica

    2011-07-01

    Verification of radiotherapy treatments in head and neck requires, among other things, small volume chambers and a phantom to reproduce the geometry and density of the anatomical structure. New documents from the ICRU (International Commission on Radiation Units and Measurements), Report 83, established the need for quality control in radiotherapy with special techniques such as IMRT (intensity-modulated radiation therapy). In this study, we built a cylindrical acrylic phantom with standing water, containing seven measuring points in the transverse plane and free location (0-20 cm) in the longitudinal plane. These points of measurement are constituted by cavities for the accommodation of the ionization chamber of 7 mm of mayor diameter (semi flex, pinpoint with build cup). The results of the phantom validation yielded percentage differences less than 1% in fixed beams and less than 2.5% in arc therapy for TPS Eclipse calculation. The preparation of this phantom, particularly made to verify the head and neck treatments, was simple and reliable for checking the dose in radiotherapy with fixed beams and/or special techniques such as arc therapy or IMRT, so that will be sent to various radiotherapy centers in the country for dosimetric verification in such treatments. (author)

  7. 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

  8. 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

  9. Development of a head phantom to be used for quality control in stereotactic radiosurgery

    International Nuclear Information System (INIS)

    Barbosa, Nilseia Aparecida

    2010-05-01

    It was designed and developed a geometric acrylic head phantom (GHP) for Quality Assurance (QA) in Stereotactic Radiosurgery (SRS). Inside the phantom there are inserts that are able to accommodate acrylic targets representing the tumor tissue and organ at risk in the region cranial brain, the brain stem. The tumor tissue is represented by two semi-spheres of acrylic with a diameter of 13.0 mm and cavities in the central region for accommodation of a TLD-100 detector and a small radiochromic EBT Gafchromic filmstrip. The brain stem is represented by the two parts of acrylic cylinder with a diameter 18.0 mm, 38.0 mm length and cavities along the central region to accommodate the 5 detectors TLD-100 and yet another of EBT film. The distance tumor - brain stem is 2.0 mm. The experimental setup was filled with water, attached to the stereotactic frame to determine the coordinates of the target and underwent computed tomography (CT). Cf images were transferred to the SRS planning system BrainLab (BrainScan). The contours of the lesion and organ at risk were delineated and, through the technique of multiple circular arcs, the planning was conduced with five arches, one isocenter and a collimator of 17.5 mm from the combination between the table and gantry . The dose delivered to the isocenter of the lesion was 3.0 Gy and the total coverage of tumor volume corresponds to the 75% isodose. This experimental arrangement is subjected to radiosurgery treatment, after which the dosimeters are evaluated and their responses compared with the values of planned doses. The linear accelerator used was a Varian CLlNAC 2300 CID, photon beam of 6 MV, installed at the National Cancer Institute (INCA). For verification of dose distributions in 3D, the films were irradiated in three planes: sagittal, caronal and axial. The .films were scanned and digitized on a scanner Microtek ScanMaker 9800XL model. The dose distributions in irradiated films were compared with the distributions of doses

  10. Development of a unique phantom to assess dose error of metal artifact in head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Young; Kang, Sang Won; Suh, Tae Suk [Dept. of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Lee, Jeong Woo [Dept. of Radiation Oncology, Konkuk University Medical Center, Seoul (Korea, Republic of); Park, Ji Yeon [Dept. of Pediatrics and Molecular Imaging Program at Stanford, Stanford University, Stanford (United States)

    2016-04-15

    The artifacts not only blur the CT images and lead to inaccuracies in diagnosis, but also make the delineation of anatomical structures intractable, which is important in image-guided intervention procedures. These artifacts obscure the underlying anatomy, leading to uncertainty in the delineation of the target volumes and compromising the integrity of the density representation that is crucial for accurate dose calculation. Because head and neck cancer patients tend to be over the age of 50 years, they constitute a group likely to have dental prostheses. This kind of side effects considerably disturbs the therapeutic procedure. Radiation scatter from high atomic number (Z) materials is established to cause both soft tissue and bony complications in the oral cavity, making scattered radiation an important factor in head and neck region radiotherapy planning. In this study, we carried out theoretical analysis of the metal artifact, that is, streak artifact and dark artifact, and also critical analysis of dosimetric effect which cause by dental implants in CT images of head and neck cancer patients with the genuine teeth and implants inserted humanoid phantom. The phantom provides a unique and useful tool in head and neck dosimetry research. It can be used in the development of new imaging instrumentation, image acquisition strategies, and image processing and reconstruction methods.

  11. Experience of development and testing of a new model of an anthropomorphic radiodosimetric phantom of the human body ARDF-10 'Roman'

    International Nuclear Information System (INIS)

    Bruhov, R.E.; Finkel, F.V.

    2013-01-01

    In 2006-2010 by the commission of the Radiation and Nuclear Safety Authority in Finland applied scientific research and development of a new model of an anthropomorphic radio dosimetric phantom of the human body (the Phantom) were performed, after the development of the production technology and initial testing in 2010-2012 the first serial copy of the Phantom under the name ARDF-10 ROMAN was produced. The main application of the new model of the Phantom ARDF-10 ROMAN: - increase of the precision of calibration and implementation of the periodic monitoring of Whole body counters (WBC) equipment, standardization of measurement procedure for inter-laboratory comparisons of the incorporated activity. - metrological support of the development and implementation of new methods for human radiation spectrometry: identification of radionuclide content of incorporated activity in the human body; measurements of the activity of incorporated technogenic and natural radionuclides in the whole body and in the lungs; measurements of 90 Sr content in the bone tissue. Study of the mechanisms of the intake, distribution, accumulation and excretion of the radionuclides in the human body, such as: daughter products of 222 Rn decay in the respiratory tract, 241 Am, other transuranic elements; isotopes of iodine in the thyroid gland; radiopharmaceuticals administered to patients for diagnostic and medicinal purposes. Obtaining estimates of spatial-temporal distribution of individual internal exposure dose of a human. The result of the work of recent years has been the creation of hygienic safe standard sample of an anthropomorphic radio dosimetric phantom of the human body ARDF-10 ROMAN, consisting of 4 anthropometric models of body parts, which are independent assembly units (head phantom, neck phantom, torso phantom, knee phantom). Phantom models are made from simulators of bone, soft (muscle) and lungs biological tissue. The Phantom contains 28 separate elements. To the first

  12. Dosimetry in phantom of newborn head for computerized tomography signs with voltages of 80, 100 and 120 KV

    International Nuclear Information System (INIS)

    Oliveira, G.A.P.; Mourão, A.P.

    2017-01-01

    Computed Tomography is the radiodiagnostic method that most contributes to the dose deposition in population. Therefore, the dose reductions used in these tests are very important, especially for pediatric patients who have a life expectancy greater than the rest of the population. This study purpose to compare the doses generated from newborns (NB) with different voltages in a 64-channel multichannel CT equipment of the GE brand. One head phantom in a cylindrical shape made in PMMA were used to newborn patient dimensions. 100 mA.s of charge of the X-ray tube were standardized, alternating the voltages between 80, 100, 120 kV in the axial acquisition. The absorbed dose measurements were performed with a pencil-type ionization chamber positioned within the five apertures in the phantom. The phantom was developed with the cephalic percentile of male NB of 14 and female of 28 days, respectively. The doses obtained in the head phantom of NB were compared with the voltages of 80, 100 and 120 kV. The volumetric dose index, C VOL , generated in the 120 kV protocol was 25.10 mGy, for 100 kV of 19,06 mGy and not for 80 kV 15,81 mGy. The results allow to evaluate that for the generation of images with 120 kV, the dose was 37.0% higher when compared to the voltage of 80 kV. The study shows that the increase in tension in the tomography protocols also makes it possible to increase the dose for the NB patient. (author)

  13. Dosimetry in phantom of newborn head for computerized tomography signs with voltages of 80, 100 and 120 KV

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, G.A.P.; Mourão, A.P., E-mail: giovanni.paiva@pbh.gov.br, E-mail: apratabhz@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2017-07-01

    Computed Tomography is the radiodiagnostic method that most contributes to the dose deposition in population. Therefore, the dose reductions used in these tests are very important, especially for pediatric patients who have a life expectancy greater than the rest of the population. This study purpose to compare the doses generated from newborns (NB) with different voltages in a 64-channel multichannel CT equipment of the GE brand. One head phantom in a cylindrical shape made in PMMA were used to newborn patient dimensions. 100 mA.s of charge of the X-ray tube were standardized, alternating the voltages between 80, 100, 120 kV in the axial acquisition. The absorbed dose measurements were performed with a pencil-type ionization chamber positioned within the five apertures in the phantom. The phantom was developed with the cephalic percentile of male NB of 14 and female of 28 days, respectively. The doses obtained in the head phantom of NB were compared with the voltages of 80, 100 and 120 kV. The volumetric dose index, C{sub VOL}, generated in the 120 kV protocol was 25.10 mGy, for 100 kV of 19,06 mGy and not for 80 kV 15,81 mGy. The results allow to evaluate that for the generation of images with 120 kV, the dose was 37.0% higher when compared to the voltage of 80 kV. The study shows that the increase in tension in the tomography protocols also makes it possible to increase the dose for the NB patient. (author)

  14. Comparison of organ doses in human phantoms: variations due to body size and posture

    International Nuclear Information System (INIS)

    Feng, Xu; Xiang-Hong, Jia; Xue-Jun, Yu; Zhan-Chun, Pan; Qian, Liu; Chun-Xin, Yang

    2017-01-01

    Organ dose calculations performed using human phantoms can provide estimates of astronauts' health risks due to cosmic radiation. However, the characteristics of such phantoms strongly affect the estimation precision. To investigate organ dose variations with body size and posture in human phantoms, a non-uniform rational B-spline boundary surfaces model was constructed based on cryo-section images. This model was used to establish four phantoms with different body size and posture parameters, whose organs parameters were changed simultaneously and which were voxelised with 4x4x4 mm"3 resolution. Then, using Monte Carlo transport code, the organ doses caused by ≤500 MeV isotropic incident protons were calculated. The dose variations due to body size differences within a certain range were negligible, and the doses received in crouching and standing-up postures were similar. Therefore, a standard Chinese phantom could be established, and posture changes cannot effectively protect astronauts during solar particle events. (authors)

  15. Adaptation and validation of a commercial head phantom for cranial radiosurgery dosimetry end-to-end audit.

    Science.gov (United States)

    Dimitriadis, Alexis; Palmer, Antony L; Thomas, Russell A S; Nisbet, Andrew; Clark, Catharine H

    2017-06-01

    To adapt and validate an anthropomorphic head phantom for use in a cranial radiosurgery audit. Two bespoke inserts were produced for the phantom: one for providing the target and organ at risk for delineation and the other for performing dose measurements. The inserts were tested to assess their positional accuracy. A basic treatment plan dose verification with an ionization chamber was performed to establish a baseline accuracy for the phantom and beam model. The phantom and inserts were then used to perform dose verification measurements of a radiosurgery plan. The dose was measured with alanine pellets, EBT extended dose film and a plastic scintillation detector (PSD). Both inserts showed reproducible positioning (±0.5 mm) and good positional agreement between them (±0.6 mm). The basic treatment plan measurements showed agreement to the treatment planning system (TPS) within 0.5%. Repeated film measurements showed consistent gamma passing rates with good agreement to the TPS. For 2%-2 mm global gamma, the mean passing rate was 96.7% and the variation in passing rates did not exceed 2.1%. The alanine pellets and PSD showed good agreement with the TPS (-0.1% and 0.3% dose difference in the target) and good agreement with each other (within 1%). The adaptations to the phantom showed acceptable accuracies. The presence of alanine and PSD do not affect film measurements significantly, enabling simultaneous measurements by all three detectors. Advances in knowledge: A novel method for thorough end-to-end test of radiosurgery, with capability to incorporate all steps of the clinical pathway in a time-efficient and reproducible manner, suitable for a national audit.

  16. A new head-mounted display-based augmented reality system in neurosurgical oncology: a study on phantom.

    Science.gov (United States)

    Cutolo, Fabrizio; Meola, Antonio; Carbone, Marina; Sinceri, Sara; Cagnazzo, Federico; Denaro, Ennio; Esposito, Nicola; Ferrari, Mauro; Ferrari, Vincenzo

    2017-12-01

    Benefits of minimally invasive neurosurgery mandate the development of ergonomic paradigms for neuronavigation. Augmented Reality (AR) systems can overcome the shortcomings of commercial neuronavigators. The aim of this work is to apply a novel AR system, based on a head-mounted stereoscopic video see-through display, as an aid in complex neurological lesion targeting. Effectiveness was investigated on a newly designed patient-specific head mannequin featuring an anatomically realistic brain phantom with embedded synthetically created tumors and eloquent areas. A two-phase evaluation process was adopted in a simulated small tumor resection adjacent to Broca's area. Phase I involved nine subjects without neurosurgical training in performing spatial judgment tasks. In Phase II, three surgeons were involved in assessing the effectiveness of the AR-neuronavigator in performing brain tumor targeting on a patient-specific head phantom. Phase I revealed the ability of the AR scene to evoke depth perception under different visualization modalities. Phase II confirmed the potentialities of the AR-neuronavigator in aiding the determination of the optimal surgical access to the surgical target. The AR-neuronavigator is intuitive, easy-to-use, and provides three-dimensional augmented information in a perceptually-correct way. The system proved to be effective in guiding skin incision, craniotomy, and lesion targeting. The preliminary results encourage a structured study to prove clinical effectiveness. Moreover, our testing platform might be used to facilitate training in brain tumour resection procedures.

  17. A three-dimensional head-and-neck phantom for validation of multimodality deformable image registration for adaptive radiotherapy

    International Nuclear Information System (INIS)

    Singhrao, Kamal; Kirby, Neil; Pouliot, Jean

    2014-01-01

    Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H and N) phantom with realistic tissue contrast for both kilovoltage (kV) and megavoltage (MV) imaging modalities and use it to objectively evaluate deformable image registration (DIR) algorithms. Methods: The phantom represents H and N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kV and MV imaging. The phantom opens along a sagittal midsection to reveal radiotransparent markers, which were used to characterize the phantom deformation. The deformed and undeformed phantoms were scanned with kV and MV imaging modalities. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM software. Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able to represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV–kV registration, MIM produced mean and maximum errors of 1.8 and 11.5 mm, respectively. These same numbers for Velocity were 2.4 and 7.1 mm, respectively. For MV–MV, kV–MV, and kV–MC Velocity produced similar mean and maximum error values. MIM, however, produced gross errors for all three of these scenarios, with maximum errors ranging from 33.4 to 41.6 mm. Conclusions: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H and N phantom is an effective tool

  18. Generation of a head phantom according to the 95. percentile Chinese population data for evaluating the specific absorption rate by wireless communication devices

    International Nuclear Information System (INIS)

    Ma, Yu; Wang, Yuduo; Shao, Qing; Wu, Tongning; Li, Congsheng

    2014-01-01

    A Chinese head phantom (CHP) is constructed for evaluating the specific absorption rate (SAR) by the wireless transceivers. The dimensions of the head phantom are within 4 % difference compared with the 95. percentile data from the China's standard. The shell's thickness and the configuration of the pinna are the same as those of the specific anthropomorphic mannequin (SAM). Three computable models for the mobile phones are generated and used in the SAR simulations with the SAM and the CHP. The results show that the simulated SAR from the SAM head is similar. Its morphological reason has been analysed. The authors discuss the conservativeness of the two head phantoms as well. The CHP can be used in the inter-laboratory evaluation for the SAR uncertainty. It can also provide the information for the SAR variability due to physical difference, which will benefit the maintenance and the harmonisation of the standards. (authors)

  19. Modelling of UWB Antenna Perturbed by Human Phantom in Spherical Harmonics Space

    DEFF Research Database (Denmark)

    Mhedhbi, Meriem; Avrillon, Stephane; Pedersen, Troels

    2014-01-01

    is attractive for simulation purposes. We propose a simple model for the spherical harmonics coefficients allowing to predict the antenna behavior perturbed by a human phantom. The model is based on knowledge of the spherical harmonic coefficients of antenna in free space and the antenna-phantom distance.......In this paper we study how the antenna radiation pattern is perturbed in the presence of a human phantom in terms of changes in the coefficients of the spherical harmonic antenna representation. The spherical harmonic basis allows for a compact representation of the antenna pattern which...

  20. Cost-effective pediatric head and body phantoms for computed tomography dosimetry and its evaluation using pencil ion chamber and CT dose profiler

    Directory of Open Access Journals (Sweden)

    A Saravanakumar

    2015-01-01

    Full Text Available In the present work, a pediatric head and body phantom was fabricated using polymethyl methacrylate (PMMA at a low cost when compared to commercially available phantoms for the purpose of computed tomography (CT dosimetry. The dimensions of head and body phantoms were 10 cm diameter, 15 cm length and 16 cm diameter, 15 cm length, respectively. The dose from a 128-slice CT machine received by the head and body phantom at the center and periphery were measured using a 100 mm pencil ion chamber and 150 mm CT dose profiler (CTDP. Using these values, the weighted computed tomography dose index (CTDIw and in turn the volumetric CTDI (CTDIv were calculated for various combinations of tube voltage and current-time product. A similar study was carried out using standard calibrated phantom and the results have been compared with the fabricated ones to ascertain that the performance of the latter is equivalent to that of the former. Finally, CTDIv measured using fabricated and standard phantoms were compared with respective values displayed on the console. The difference between the values was well within the limits specified by Atomic Energy Regulatory Board (AERB, India. These results indicate that the cost-effective pediatric phantom can be employed for CT dosimetry.

  1. Systematic biases in human heading estimation.

    Directory of Open Access Journals (Sweden)

    Luigi F Cuturi

    Full Text Available Heading estimation is vital to everyday navigation and locomotion. Despite extensive behavioral and physiological research on both visual and vestibular heading estimation over more than two decades, the accuracy of heading estimation has not yet been systematically evaluated. Therefore human visual and vestibular heading estimation was assessed in the horizontal plane using a motion platform and stereo visual display. Heading angle was overestimated during forward movements and underestimated during backward movements in response to both visual and vestibular stimuli, indicating an overall multimodal bias toward lateral directions. Lateral biases are consistent with the overrepresentation of lateral preferred directions observed in neural populations that carry visual and vestibular heading information, including MSTd and otolith afferent populations. Due to this overrepresentation, population vector decoding yields patterns of bias remarkably similar to those observed behaviorally. Lateral biases are inconsistent with standard bayesian accounts which predict that estimates should be biased toward the most common straight forward heading direction. Nevertheless, lateral biases may be functionally relevant. They effectively constitute a perceptual scale expansion around straight ahead which could allow for more precise estimation and provide a high gain feedback signal to facilitate maintenance of straight-forward heading during everyday navigation and locomotion.

  2. A heterogeneous human tissue mimicking phantom for RF heating and MRI thermal monitoring verification.

    Science.gov (United States)

    Yuan, Yu; Wyatt, Cory; Maccarini, Paolo; Stauffer, Paul; Craciunescu, Oana; Macfall, James; Dewhirst, Mark; Das, Shiva K

    2012-04-07

    This paper describes a heterogeneous phantom that mimics a human thigh with a deep-seated tumor, for the purpose of studying the performance of radiofrequency (RF) heating equipment and non-invasive temperature monitoring with magnetic resonance imaging (MRI). The heterogeneous cylindrical phantom was constructed with an outer fat layer surrounding an inner core of phantom material mimicking muscle, tumor and marrow-filled bone. The component materials were formulated to have dielectric and thermal properties similar to human tissues. The dielectric properties of the tissue mimicking phantom materials were measured with a microwave vector network analyzer and impedance probe over the frequency range of 80-500 MHz and at temperatures of 24, 37 and 45 °C. The specific heat values of the component materials were measured using a differential scanning calorimeter over the temperature range of 15-55 °C. The thermal conductivity value was obtained from fitting the curves obtained from one-dimensional heat transfer measurement. The phantom was used to verify the operation of a cylindrical four-antenna annular phased array extremity applicator (140 MHz) by examining the proton resonance frequency shift (PRFS) thermal imaging patterns for various magnitude/phase settings (including settings to focus heating in tumors). For muscle and tumor materials, MRI was also used to measure T1/T2* values (1.5 T) and to obtain the slope of the PRFS phase change versus temperature change curve. The dielectric and thermal properties of the phantom materials were in close agreement to well-accepted published results for human tissues. The phantom was able to successfully demonstrate satisfactory operation of the tested heating equipment. The MRI-measured thermal distributions matched the expected patterns for various magnitude/phase settings of the applicator, allowing the phantom to be used as a quality assurance tool. Importantly, the material formulations for the various tissue types

  3. Reconstruction of segmented human voxel phantoms for skin dosimetry

    International Nuclear Information System (INIS)

    Antunes, Paula C.G.; Siqueira, Paulo de Tarso D.; Yoriyaz, Helio; Fonseca, Gabriel P.; Reis, Gabriela; Furnari, Laura

    2009-01-01

    High-resolution medical images along with methods that simulate the interaction of radiation with matter, as the Monte Carlo radiation transport codes, have been widely used in medical physics procedures. These images provide the construction of realistic anatomical models, which after being coupled to these codes, may drive to better assessments of dose distributions on the patient. These anatomical models constructed from medical images are known as voxel phantoms (voxel - volume element of an image). Present day regular images are unsuitable to correctly perform skin dose distribution evaluations. This inability is due to improper skin discrimination in most of the current medical images, once its thickness stands below the resolution of the pixels that form the image. This paper proposes the voxel phantom reconstruction by subdividing and segmenting the elements that form the phantom. It is done in order to better discriminate the skin by assigning it more adequate thickness and actual location, allowing a better dosimetric evaluation of the skin. This task is an important issue in many radiotherapy procedures. Particular interest lays in Total Skin Irradiation (TSI) with electron beams, where skin dose evaluation stands as the treatment key point of the whole body irradiation. This radiotherapy procedure is under implementation at the Hospital das Clinicas da Universidade de Sao Paulo (HC-USP). (author)

  4. Computational voxel phantom, associated to anthropometric and anthropomorphic real phantom for dosimetry in human male pelvis radiotherapy

    International Nuclear Information System (INIS)

    Silva, Cleuza Helena Teixeira; Campos, Tarcisio Passos Ribeiro de

    2005-01-01

    This paper addresses a computational model of voxels through MCNP5 Code and the experimental development of an anthropometric and anthropomorphic phantom for dosimetry in human male pelvis brachytherapy focusing prostatic tumors. For elaboration of the computational model of the human male pelvis, anatomical section images from the Visible Man Project were applied. Such selected and digital images were associated to a numeric representation, one for each section. Such computational representation of the anatomical sections was transformed into a bi-dimensional mesh of equivalent tissue. The group of bidimensional meshes was concatenated forming the three-dimensional model of voxels to be used by the MCNP5 code. In association to the anatomical information, data from the density and chemical composition of the basic elements, representatives of the organs and involved tissues, were setup in a material database for the MCNP-5. The model will be applied for dosimetric evaluations in situations of irradiation of the human masculine pelvis. Such 3D model of voxel is associated to the code of transport of particles MCNP5, allowing future simulations. It was also developed the construction of human masculine pelvis phantom, based on anthropometric and anthropomorphic dates and in the use of representative equivalent tissues of the skin, fatty, muscular and glandular tissue, as well as the bony structure.This part of work was developed in stages, being built the bony cast first, later the muscular structures and internal organs. They were then jointly mounted and inserted in the skin cast. The representative component of the fatty tissue was incorporate and accomplished the final retouchings in the skin. The final result represents the development of two important essential tools for elaboration of computational and experimental dosimetry. Thus, it is possible its use in calibrations of pre-existent protocols in radiotherapy, as well as for tests of new protocols, besides

  5. Diffusion Capillary Phantom vs. Human Data: Outcomes for Reconstruction Methods Depend on Evaluation Medium

    Directory of Open Access Journals (Sweden)

    Sarah D. Lichenstein

    2016-09-01

    Full Text Available Purpose: Diffusion MRI provides a non-invasive way of estimating structural connectivity in the brain. Many studies have used diffusion phantoms as benchmarks to assess the performance of different tractography reconstruction algorithms and assumed that the results can be applied to in vivo studies. Here we examined whether quality metrics derived from a common, publically available, diffusion phantom can reliably predict tractography performance in human white matter tissue. Material and Methods: We compared estimates of fiber length and fiber crossing among a simple tensor model (diffusion tensor imaging, a more complicated model (ball-and-sticks and model-free (diffusion spectrum imaging, generalized q-sampling imaging reconstruction methods using a capillary phantom and in vivo human data (N=14. Results: Our analysis showed that evaluation outcomes differ depending on whether they were obtained from phantom or human data. Specifically, the diffusion phantom favored a more complicated model over a simple tensor model or model-free methods for resolving crossing fibers. On the other hand, the human studies showed the opposite pattern of results, with the model-free methods being more advantageous than model-based methods or simple tensor models. This performance difference was consistent across several metrics, including estimating fiber length and resolving fiber crossings in established white matter pathways. Conclusions: These findings indicate that the construction of current capillary diffusion phantoms tends to favor complicated reconstruction models over a simple tensor model or model-free methods, whereas the in vivo data tends to produce opposite results. This brings into question the previous phantom-based evaluation approaches and suggests that a more realistic phantom or simulation is necessary to accurately predict the relative performance of different tractography reconstruction methods. Acronyms: BSM: ball-and-sticks model; d

  6. Measurements and calculations of neutron spectra and neutron dose distribution in human phantoms

    International Nuclear Information System (INIS)

    Palfalvi, J.

    1984-11-01

    The measurement and calculation of the radiation field around and in a phantom, with regard to the neutron component and the contaminating gamma radiation, are essential for radiation protection and radiotherapy purposes. The final report includes the development of the simple detector system, automized detector measuring facilities and a computerized evaluating system. The results of the depth dose and neutron spectra experiments and calculations in a human phantom are given

  7. A Chinese Visible Human-based computational female pelvic phantom for radiation dosimetry simulation

    International Nuclear Information System (INIS)

    Nan, H.; Jinlu, S.; Shaoxiang, Z.; Qing, H.; Li-wen, T.; Chengjun, G.; Tang, X.; Jiang, S. B.; Xiano-lin, Z.

    2010-01-01

    Accurate voxel phantom is needed for dosimetric simulation in radiation therapy for malignant tumors in female pelvic region. However, most of the existing voxel phantoms are constructed on the basis of Caucasian or non-Chinese population. Materials and Methods: A computational framework for constructing female pelvic voxel phantom for radiation dosimetry was performed based on Chinese Visible Human datasets. First, several organs within pelvic region were segmented from Chinese Visible Human datasets. Then, polygonization and voxelization were performed based on the segmented organs and a 3D computational phantom is built in the form of a set of voxel arrays. Results: The generated phantom can be converted and loaded into treatment planning system for radiation dosimetry calculation. From the observed dosimetric results of those organs and structures, we can evaluate their absorbed dose and implement some simulation studies. Conclusion: A voxel female pelvic phantom was developed from Chinese Visible Human datasets. It can be utilized for dosimetry evaluation and planning simulation, which would be very helpful to improve the clinical performance and reduce the radiation toxicity on organ at risk.

  8. Experimental Determination of the Neutron Radiation-Dose Distribution in the Human Phantom

    Energy Technology Data Exchange (ETDEWEB)

    Stipcic, Neda [Institute Rudjer Bogkovic, Zagreb, Yugoslavia (Serbia)

    1967-01-15

    The quality of the radiation delivering the radiation dose to the human phantom is quite different from that of the incident neutron beam. This paper describes the experimental investigation of the variation of neutron dose related to the variation of neutron fluence with depth in the human phantom. The distribution of neutron radiation was determined in the human phantom - a cube of paraffin wax 25 cm x 25 cm x 50 cm with a density of 0.92 cm{sup -3}. Po-Be and Ra-Be point sources were used as neutron sources. Neutron fluences were measured using different types of detector: scintillation detector, BF{sub 3} counter, and nuclear-track emulsions. Since the fluence measurements with these three types of detectors were carried out under the same experimental conditions, it was possible to separate and analyse each part of the radiation dose in the paraffin. From the investigations, the distribution of the total radiation dose was obtained as a function of the paraffin depth. The maximum value of this dose distribution is constant with respect to the distance between the source and the paraffin phantom. From the results obtained, some conclusions may be drawn concerning the amount of absorbed radiation dose in the human phantom. (author)

  9. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

    Science.gov (United States)

    Anderson, Danielle; Siegbahn, E. Albert; Fallone, B. Gino; Serduc, Raphael; Warkentin, Brad

    2012-05-01

    This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm2 microbeam array in each phantom, as well as a 16 × 16 mm2 array in the 8 cm cat head, and a 32 × 32 mm2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2-49 (mouse) and 2-46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2-87% and 33-96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this study

  10. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

    International Nuclear Information System (INIS)

    Anderson, Danielle; Fallone, B Gino; Warkentin, Brad; Siegbahn, E Albert; Serduc, Raphael

    2012-01-01

    This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm 2 microbeam array in each phantom, as well as a 16 × 16 mm 2 array in the 8 cm cat head, and a 32 × 32 mm 2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2–49 (mouse) and 2–46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2–87% and 33–96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this

  11. Determination of appropriate exposure angles for the reverse water's view using a head phantom

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Su; Lee, Keun Ohk [Dept. of Radiology, Soonchunhyang University Hospital, Bucheon (Korea, Republic of); Choi, Jae Ho [Dept. of Radiological Technology, Ansan University, Ansan (Korea, Republic of); Jung, Jae Hong [Dept. of Biomedical Engineering, College of Medicine, The Catholic University, Seoul (Korea, Republic of)

    2017-06-15

    Early diagnosis for upper facial trauma is difficult by using the standard Water's view (S-Water's) in general radiograph due to overlapping of anatomical structures, the uncertainty of patient positioning, and specific patients with obese, pediatric, old, or high-risk. The purpose of this study was to analyze appropriate exposure angles through a comparison of two different protocols (S-Water's vs. reverse Water's view (R-Water's)) by using a head phantom. A head phantom and general radiograph with 75 kVp, 400 mA, 45 ms 18 mAs, and SID 100 cm. Images of R-Water's were obtained by different angles in the range of 0 degree to 50 degrees, which adjusted an angle at 1 degree interval in supine position. Survey elements were developed and three observers were evaluated with four elements including the maxillary sinus, zygomatic arch, petrous ridge, and image distortion. Statistical significant analysis were used the Krippendorff's alpha and Fleiss' kappa. The intra-class correlation (ICC) coefficient for three observers were high with maxillary, 0.957 (0.903, 0.995); zygomatic arch, 0.939 (0.866, 0.987); petrous ridge, 0.972 (0.897, 1.000); and image distortion, 0.949 (0.830, 1.000). The high-quality image (HI) and perfect agreement (PA) for acquired exposure angles were high in range of the maxillary sinus (36 degrees – 44 degrees), zygomatic arch (33 degrees – 40 degrees), petrous ridge (32 degrees – 50 degrees), and image distortion (44 degrees– 50 degrees). Consequently, an appropriate exposure angles for the R-Water's view in the supine position for patients with facial trauma are in the from 36 degrees to 40 degrees in this phantom study. The results of this study will be helpful for the rapid diagnosis of facial fractures by simple radiography.

  12. Determination of appropriate exposure angles for the reverse water's view using a head phantom

    International Nuclear Information System (INIS)

    Lee, Min Su; Lee, Keun Ohk; Choi, Jae Ho; Jung, Jae Hong

    2017-01-01

    Early diagnosis for upper facial trauma is difficult by using the standard Water's view (S-Water's) in general radiograph due to overlapping of anatomical structures, the uncertainty of patient positioning, and specific patients with obese, pediatric, old, or high-risk. The purpose of this study was to analyze appropriate exposure angles through a comparison of two different protocols (S-Water's vs. reverse Water's view (R-Water's)) by using a head phantom. A head phantom and general radiograph with 75 kVp, 400 mA, 45 ms 18 mAs, and SID 100 cm. Images of R-Water's were obtained by different angles in the range of 0 degree to 50 degrees, which adjusted an angle at 1 degree interval in supine position. Survey elements were developed and three observers were evaluated with four elements including the maxillary sinus, zygomatic arch, petrous ridge, and image distortion. Statistical significant analysis were used the Krippendorff's alpha and Fleiss' kappa. The intra-class correlation (ICC) coefficient for three observers were high with maxillary, 0.957 (0.903, 0.995); zygomatic arch, 0.939 (0.866, 0.987); petrous ridge, 0.972 (0.897, 1.000); and image distortion, 0.949 (0.830, 1.000). The high-quality image (HI) and perfect agreement (PA) for acquired exposure angles were high in range of the maxillary sinus (36 degrees – 44 degrees), zygomatic arch (33 degrees – 40 degrees), petrous ridge (32 degrees – 50 degrees), and image distortion (44 degrees– 50 degrees). Consequently, an appropriate exposure angles for the R-Water's view in the supine position for patients with facial trauma are in the from 36 degrees to 40 degrees in this phantom study. The results of this study will be helpful for the rapid diagnosis of facial fractures by simple radiography

  13. Activity quantification of phantom using dual-head SPECT with two-view planar image

    International Nuclear Information System (INIS)

    Guo Leiming; Chen Tao; Sun Xiaoguang; Huang Gang

    2005-01-01

    The absorbed radiation dose from internally deposited radionuclide is a major factor in assessing risk and therapeutic utility in nuclear medicine diagnosis or treatment. The quantification of absolute activity in vivo is necessary procedure of estimating the absorbed dose of organ or tissue. To understand accuracy in the determination of organ activity, the experiments on 99 Tc m activity quantification were made for a body phantom using dual-heat SPECT with the two-view counting technique. Accuracy in the activity quantification is credible and is not affected by depth of source organ in vivo. When diameter of the radiation source is ≤2 cm, the most accurate activity quantification result can be obtained on the basis of establishing the system calibration factor and transmission factor. The use of Buijs's method is preferable, especially at very low source-to-background activity concentration rations. (authors)

  14. [The model of geometrical human body phantom for calculating tissue doses in the service module of the International Space Station].

    Science.gov (United States)

    Bondarenko, V A; Mitrikas, V G

    2007-01-01

    The model of a geometrical human body phantom developed for calculating the shielding functions of representative points of the body organs and systems is similar to the anthropomorphic phantom. This form of phantom can be integrated with the shielding model of the ISS Russian orbital segment to make analysis of radiation loading of crewmembers in different compartments of the vehicle. Calculation of doses absorbed by the body systems in terms of the representative points makes it clear that doses essentially depend on the phantom spatial orientation (eye direction). It also enables the absorbed dose evaluation from the shielding functions as the mean of the representative points and phantom orientation.

  15. Quantitative analysis of orthopedic metal artefact reduction in 64-slice computed tomography scans in large head metal-on-metal total hip replacement, a phantom study

    NARCIS (Netherlands)

    Boomsma, Martijn F.; Warringa, Niek; Edens, Mireille A.; Mueller, Dirk; Ettema, Harmen B.; Verheyen, Cees C. P. M.; Maas, Mario

    2016-01-01

    Purpose: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. Background: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose

  16. Chinese reference human voxel phantoms for radiation protection: development, application and recent progress

    International Nuclear Information System (INIS)

    Pan Yuxi; Qiu Rui; Ren Li; Zhu Huanjun; Li Junli; Liu Liye

    2014-01-01

    This paper presents the work of constructing Chinese reference human voxel phantoms, taking Chinese reference adult female voxel model for example. In this study, a site-specific skeleton structure was built, some radiation sensitive organs were supplemented. Organ sub-segmentation was taken into account. The constructed phantoms include almost all radiation sensitive organs required by ICRP new recommendation. Masses of the organs are almost consistent with the Chinese reference data within 5%. The Chinese reference human phantoms have been applied both in internal dosimetry and external dosimetry. The results provide fundamental data for Chinese radiation dosimetry. In addition, the newly established detailed breast model and micro-bone model were introduced. (authors)

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

    International Nuclear Information System (INIS)

    Wang Wen; Hu Liqin; Cheng Mengyun; Long Pengcheng

    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. (authors)

  18. The immunologic considerations in human head transplantation.

    Science.gov (United States)

    Hardy, Mark A; Furr, Allen; Barret, Juan P; Barker, John H

    2017-05-01

    The idea of head transplantation appears at first as unrealistic, unethical, and futile. Here we discuss immunological considerations in human head transplantation. In a separate accompanying article we discuss surgical, ethical, and psychosocial issues concerned in body-to-head transplantation (BHT) [1]. The success of such an unusual allograft, where the donor and the recipient can reject each other, depends on prevention of complex immunologic reactions, especially rejection of the head by the body (graft-vs-host) or probably less likely, the possibility of the head rejecting the total body allograft (host-vs-graft). The technical and immunologic difficulties are enormous, especially since rapid nerve and cord connections and regeneration have not yet been possible to achieve. In this article we begin by briefly reviewing neuro-immunologic issues that may favor BHT such as the blood brain barrier (BBB) and point out its shortcomings. And we touch on the cellular and humoral elements in the brain proper that differ in some respects from those in other organs and in the periphery. Based on recent successes in vascular composite allografts (VCAs), we will elaborate on potential specific advantages and difficulties in BHT of various available immunosuppressive medications already utilized in VCAs. The risk/benefit ratio of these drugs will be emphasized in relation to direct brain toxicity such as seizure disorders, interference, or promotion of nerve regeneration, and potentiation of cerebral viral infections. The final portion of this article will focus on pre-transplant immunologic manipulation of the deceased donor body along with pretreatment of the recipient. Copyright © 2017 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

  19. Development and application of the Chinese adult female computational phantom Rad-HUMAN

    International Nuclear Information System (INIS)

    Wu, Yican; Cheng, Mengyun; Wang, Wen; Fan, Yanchang; Zhao, Kai; He, Tao; Pei, Xi; Shang, Leiming; Chen, Chaobin; Long, Pengcheng; Cao, Ruifen; Wang, Guozhong; Zhou, Shaoheng; Yu, Shengpeng; Hu, Liqin; Zeng, Q.

    2013-01-01

    Rad-HUMAN is a whole-body numerical phantom of a Chinese adult woman which contains 46 organs and tissues and was created by MCAM6 software using the color photographs of the Chinese Visible Human dataset. This dataset was obtained from a 22-year old Chinese female cadaver judged to represent normal human anatomy as much as possible. The density and elemental composition recommended in the ICRP Publication 89 and in the ICRU report 44 were assigned to the organ and tissue in Rad-HUMAN for radiation protection purpose. The last step was to implement the anatomical data into a Monte Carlo code. Rad-HUMAN contains more than 28.8 billion tiny volume units, which produces an accurately whole-body numerical phantom of a Chinese adult female

  20. Radiation dose verification using real tissue phantom in modern radiotherapy techniques

    International Nuclear Information System (INIS)

    Gurjar, Om Prakash; Mishra, S.P.; Bhandari, Virendra; Pathak, Pankaj; Patel, Prapti; Shrivastav, Garima

    2014-01-01

    In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as 'head phantom' and goat meat as 'tissue phantom'. The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD): 0.74), 2.36 (SD: 0.77), 3.62 (SD: 1.05), and 3.31 (SD: 0.78) for three-dimensional conformal radiotherapy (3DCRT) (head phantom), intensity modulated radiotherapy (IMRT; head phantom), 3DCRT (tissue phantom), and IMRT (tissue phantom), respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%), but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body. (author)

  1. Radiation dose verification using real tissue phantom in modern radiotherapy techniques

    Directory of Open Access Journals (Sweden)

    Om Prakash Gurjar

    2014-01-01

    Full Text Available In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as "head phantom" and goat meat as "tissue phantom". The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD: 0.74, 2.36 (SD: 0.77, 3.62 (SD: 1.05, and 3.31 (SD: 0.78 for three-dimensional conformal radiotherapy (3DCRT (head phantom, intensity modulated radiotherapy (IMRT; head phantom, 3DCRT (tissue phantom, and IMRT (tissue phantom, respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%, but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body.

  2. Dosimetry and verification of 60Co total body irradiation with human phantom and semiconductor diodes

    Directory of Open Access Journals (Sweden)

    Allahverdi Mahmoud

    2007-01-01

    Full Text Available Total Body Irradiation (TBI is a form of radiotherapy used for patients prior to bone marrow or stem cell transplant to destroy any undetectable cancer cells. The dosimetry characteristics of a 60 Co unit for TBI were studied and a simple method for the calculation of the prescribed dose for TBI is presented. Dose homogeneity was verified in a human phantom. Dose measurements were made in water phantom (30 x 30 x 30 cm 3 , using farmer ionization chamber (0.6 cc, TM30010, PTW and a parallel plate ionization chamber (TM23343, PTW. Point dose measurements for AP/PA irradiation were measured in a human phantom using silicon diodes (T60010L, PTW. The lung dose was measured with an ionization chamber (0.3 cc, TM31013. The validity of the proposed algorithm was checked at TBI distance using the human phantom. The accuracy of the proposed algorithm was within 3.5%. The dose delivered to the mid-lobe of the lung was 14.14 Gy and it has been reduced to 8.16 Gy by applying the proper shield. Dose homogeneity was within ±7% for all measured points. The results indicate that a good agreement between the total prescribed and calculated midplane doses can be achieved using this method. Therefore, it could be possible to use calculated data for TBI treatments.

  3. 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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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(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 in

  5. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

    Science.gov (United States)

    Winant, Celeste D.; Aparici, Carina Mari; Zelnik, Yuval R.; Reutter, Bryan W.; Sitek, Arkadiusz; Bacharach, Stephen L.; Gullberg, Grant T.

    2012-01-01

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic 94Tc-methoxyisobutylisonitrile (94Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K1 for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K1. For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from 94Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of 99mTc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The spatiotemporal maximum

  6. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

    International Nuclear Information System (INIS)

    Winant, Celeste D; Aparici, Carina Mari; Bacharach, Stephen L; Gullberg, Grant T; Zelnik, Yuval R; Reutter, Bryan W; Sitek, Arkadiusz

    2012-01-01

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic 94 Tc-methoxyisobutylisonitrile ( 94 Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K 1 for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K 1 . For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from 94 Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of 99m Tc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The spatiotemporal

  7. Population of 224 realistic human subject-based computational breast phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, David W. [Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Wells, Jered R., E-mail: jered.wells@duke.edu [Clinical Imaging Physics Group and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Sturgeon, Gregory M. [Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 (United States); Samei, Ehsan [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Physics, Electrical and Computer Engineering, and Biomedical Engineering, and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Dobbins, James T. [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Physics and Biomedical Engineering and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Segars, W. Paul [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Lo, Joseph Y. [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Electrical and Computer Engineering and Biomedical Engineering and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States)

    2016-01-15

    Purpose: To create a database of highly realistic and anatomically variable 3D virtual breast phantoms based on dedicated breast computed tomography (bCT) data. Methods: A tissue classification and segmentation algorithm was used to create realistic and detailed 3D computational breast phantoms based on 230 + dedicated bCT datasets from normal human subjects. The breast volume was identified using a coarse three-class fuzzy C-means segmentation algorithm which accounted for and removed motion blur at the breast periphery. Noise in the bCT data was reduced through application of a postreconstruction 3D bilateral filter. A 3D adipose nonuniformity (bias field) correction was then applied followed by glandular segmentation using a 3D bias-corrected fuzzy C-means algorithm. Multiple tissue classes were defined including skin, adipose, and several fractional glandular densities. Following segmentation, a skin mask was produced which preserved the interdigitated skin, adipose, and glandular boundaries of the skin interior. Finally, surface modeling was used to produce digital phantoms with methods complementary to the XCAT suite of digital human phantoms. Results: After rejecting some datasets due to artifacts, 224 virtual breast phantoms were created which emulate the complex breast parenchyma of actual human subjects. The volume breast density (with skin) ranged from 5.5% to 66.3% with a mean value of 25.3% ± 13.2%. Breast volumes ranged from 25.0 to 2099.6 ml with a mean value of 716.3 ± 386.5 ml. Three breast phantoms were selected for imaging with digital compression (using finite element modeling) and simple ray-tracing, and the results show promise in their potential to produce realistic simulated mammograms. Conclusions: This work provides a new population of 224 breast phantoms based on in vivo bCT data for imaging research. Compared to previous studies based on only a few prototype cases, this dataset provides a rich source of new cases spanning a wide range

  8. MO-C-17A-05: A Three-Dimensional Head-And-Neck Phantom for Validation of Kilovoltage- and Megavoltage-Based Deformable Image Registration

    International Nuclear Information System (INIS)

    Kirby, N; Singhrao, K; Pouliot, J

    2014-01-01

    Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H and N) phantom with realistic tissue contrast for both kilovoltage and megavoltage computed tomography and use it to objectively evaluate deformable image registration (DIR) algorithms. Methods: The phantom represents H and N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kilovoltage (kV) and megavoltage (MV) imaging. The phantom opened along a sagittal midsection to reveal nonradiopaque markers, which were used to characterize the phantom deformation. The deformed and undeformed phantom was scanned with kV and MV computed tomography. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM Software. Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV-kV registration, MIM made the lowest mean error, and Velocity made the lowest maximum error. For MV-MV, kV-MV, and kV-MC Velocity produced both the lowest mean and lowest maximum errors. Conclusion: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H and N phantom is an effective tool for this purpose

  9. Comparison of radiation doses between newborns and 6-y-old children undergoing head, chest and abdominal CT examinations-A phantom study

    International Nuclear Information System (INIS)

    Sugimoto, N.; Aoyama, T.; Koyama, S.; Yamauchi-Kawaura, C.; Fujii, K.

    2013-01-01

    Radiation doses in paediatric computed tomography (CT) were investigated for various types of recent CT scanners with newborn and 6-y-old phantoms in which silicon-photodiode dosemeters were implanted at various organ positions. In the head, chest and abdominal CT for the newborn phantom, doses for organs within the scan region were 21-40, 3-8 and 3-12 mGy, respectively. The corresponding doses for the child phantom were 20-37, 2-11 and 4-17 mGy, respectively. In the head, chest and abdominal CT, the effective doses were respectively 2.1-3.3, 2.0-6.0 and 2.2-10.0 mSv for the newborn, and 1.0-2.0, 1.2-6.6 and 2.9-11.8 mSv for the child. Radiation doses for the newborn were at the same levels as those for the child, excepting effective doses in head CT for the newborn, which were 1.8 times higher than those for the child. (authors)

  10. Internal strain estimation for quantification of human heel pad elastic modulus: A phantom study

    DEFF Research Database (Denmark)

    Holst, Karen; Liebgott, Hervé; Wilhjelm, Jens E.

    2013-01-01

    Shock absorption is the most important function of the human heel pad. However, changes in heel pad elasticity, as seen in e.g. long-distance runners, diabetes patients, and victims of Falanga torture are affecting this function, often in a painful manner. Assessment of heel pad elasticity...... is usually based on one or a few strain measurements obtained by an external load-deformation system. The aim of this study was to develop a technique for quantitative measurements of heel pad elastic modulus based on several internal strain measures from within the heel pad by use of ultrasound images. Nine...... heel phantoms were manufactured featuring a combination of three heel pad stiffnesses and three heel pad thicknesses to model the normal human variation. Each phantom was tested in an indentation system comprising a 7MHz linear array ultrasound transducer, working as the indentor, and a connected load...

  11. Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV experimentation

    Directory of Open Access Journals (Sweden)

    Hütter Larissa

    2016-09-01

    Full Text Available Compliant phantoms of the human aortic arch can mimic patient specific cardiovascular dysfunctions in vitro. Hence, phantoms may enable elucidation of haemodynamic disturbances caused by aortic dysfunction. This paper describes the fabrication of a thin-walled silicone phantom of the human ascending aorta and brachiocephalic artery. The model geometry was determined via a meta-analysis and modelled in SolidWorks before 3D printing. The solid model surface was smoothed and scanned with a 3D scanner. An offset outer mould was milled from Ebalta S-Model board. The final phantom indicated that ABS was a suitable material for the internal model, the Ebalta S-Model board yielded a rough external surface. Co-location of the moulds during silicone pour was insufficient to enable consistent wall thickness. The resulting phantom was free of air bubbles but did not have the desired wall thickness consistency.

  12. The influence of a clear layer on near-infrared spectrophotometry measurements using a liquid neonatal head phantom

    International Nuclear Information System (INIS)

    Wolf, M.

    1999-01-01

    It is difficult to test near-infrared spectrophotometry instruments in vivo. Therefore we constructed a liquid phantom which mimics the neonatal head. It consists of a spherical 3.5 mm thick layer of silicone rubber simulating skin and bone and a 0.5 mm thick clear layer of polypropylene imitating cerebrospinal fluid. It acts as container for a liquid solution with Intralipid, 60 μmol l -1 haemoglobin and yeast. The solution was oxygenated using oxygen and then deoxygenated by the yeast. From the instrumental (Critikon 2020) algorithm, we found that with increasing scattering (0.5%, 1%, 1.5% and 2% Intralipid concentration) the reading was increasingly offset from the expected value of 0 μmol l -1 by 55.7, 68.6, 76.5 and 80.4 μmol l -1 (oxyhaemoglobin) and 16.0, 24.4, 29.6 and 31.7 μmol l -1 (deoxyhaemoglobin). This reduced the range of the oxygen saturation reading from the expected 100% to 31.5, 21.1, 14.3 and 11.5%. Haemoglobin concentration changes were increasingly underestimated by a factor of two to four. For a second algorithm based on the diffusion approximation the offsets were smaller: oxyhaemoglobin 11.4, 17.8, 22.5 and 25.1 μmol l -1 and deoxyhaemoglobin 1.3, 3.4, 5.2 and 6.0 μmol l -1 . The range of the oxygen saturation reading was higher: 41.3, 29.2, 23.4 and 16.6%. Concentration changes were underestimated by a factor of six to ten. This study demonstrates the need to develop algorithms which take into consideration anatomical structures. (author)

  13. Impact of patient weight on tumor visibility based on human-shaped phantom simulation study in PET imaging system

    Science.gov (United States)

    Musarudin, M.; Saripan, M. I.; Mashohor, S.; Saad, W. H. M.; Nordin, A. J.; Hashim, S.

    2015-10-01

    Energy window technique has been implemented in all positron emission tomography (PET) imaging protocol, with the aim to remove the unwanted low energy photons. Current practices in our institution however are performed by using default energy threshold level regardless of the weight of the patient. Phantom size, which represents the size of the patient's body, is the factor that determined the level of scatter fraction during PET imaging. Thus, the motivation of this study is to determine the optimum energy threshold level for different sizes of human-shaped phantom, to represent underweight, normal, overweight and obese patients. In this study, the scanner was modeled by using Monte Carlo code, version MCNP5. Five different sizes of elliptical-cylinder shaped of human-sized phantoms with diameter ranged from 15 to 30 cm were modeled. The tumor was modeled by a cylindrical line source filled with 1.02 MeV positron emitters at the center of the phantom. Various energy window widths, in the ranged of 10-50% were implemented to the data. In conclusion, the phantom mass volume did influence the scatter fraction within the volume. Bigger phantom caused more scattering events and thus led to coincidence counts lost. We evaluated the impact of phantom sizes on the sensitivity and visibility of the simulated models. Implementation of wider energy window improved the sensitivity of the system and retained the coincidence photons lost. Visibility of the tumor improved as an appropriate energy window implemented for the different sizes of phantom.

  14. SU-F-T-168: Development and Implementation of An Anthropomorphic Head & Neck Phantom for the Assessment of Proton Therapy Treatment Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Branco, D; Taylor, P; Frank, S; Li, H; Zhang, X; Mehrens, H; Guindani, M; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To design a Head and Neck (H&N) anthropomorphic QA phantom that the Imaging and Radiation Oncology Core Houston (IROC-H) can use to verify the quality of intensity modulated proton therapy (IMPT) H&N treatments for institutions participating in NCI clinical trials. Methods: The phantom was created to serve as a remote auditing tool for IROC-H to evaluate an institution’s IMPT planning and delivery abilities. The design was based on the composition, size, and geometry of a generalized oropharyngeal tumor and contains critical structures (parotids and spinal cord). Radiochromic film in the axial and sagittal planes and thermoluminescent dosimeters (TLD)-100 capsules were embedded in the phantom and used to perform the dose delivery evaluation. A CT simulation was used to create a passive scatter and a spot scanning treatment plan with typical clinical constraints for H&N cancer. The IMPT plan was approved by a radiation oncologist and the phantom was irradiated multiple times. The measured dose distribution using a 7%/4mm gamma analysis (85% of pixels passing) and point doses were compared with the treatment planning system calculations. Results: The designed phantom could not achieve the target dose prescription and organ at risk dose constraints with the passive scatter treatment plan. The target prescription dose could be met but not the parotid dose constraint. The average TLD point dose ratio in the target was 0.975, well within the 5% acceptance criterion. The dose distribution analysis using various acceptance criteria, 5%/4mm, 5%/3mm, 7%/4mm and 7%/5mm, had average pixel passing rates of 85.9%, 81.8%, 89.6% and 91.6%, and respectively. Conclusion: An anthropomorphic IMPT H&N phantom was designed that can assess the dose delivery of proton sites wishing to participate in clinical trials using a 5% TLD dose and 7%/4mm gamma analysis acceptance criteria.

  15. Application of the mathematical modelling and human phantoms for calculation of the organ doses

    International Nuclear Information System (INIS)

    Kluson, J.; Cechak, T.

    2005-01-01

    Increasing power of the computers hardware and new versions of the software for the radiation transport simulation and modelling of the complex experimental setups and geometrical arrangement enable to dramatically improve calculation of organ or target volume doses ( dose distributions) in the wide field of medical physics and radiation protection applications. Increase of computers memory and new software features makes it possible to use not only analytical (mathematical) phantoms but also allow constructing the voxel models of human or phantoms with voxels fine enough (e.g. 1·1·1 mm) to represent all required details. CT data can be used for the description of such voxel model geometry .Advanced scoring methods are available in the new software versions. Contribution gives the overview of such new possibilities in the modelling and doses calculations, discusses the simulation/approximation of the dosimetric quantities ( especially dose ) and calculated data interpretation. Some examples of application and demonstrations will be shown, compared and discussed. Present computational tools enables to calculate organ or target volumes doses with new quality of large voxel models/phantoms (including CT based patient specific model ), approximating the human body with high precision. Due to these features has more and more importance and use in the fields of medical and radiological physics, radiation protection, etc. (authors)

  16. Can fruits and vegetables be used as substitute phantoms for normal human brain tissues in magnetic resonance imaging?

    International Nuclear Information System (INIS)

    Teramoto, Daisuke; Ushioda, Yuichi; Sasaki, Ayaka; Sakurai Yuki; Nagahama, Hiroshi; Nakamura, Manami; Sugimori, Hiroyuki; Sakata, Motomichi

    2013-01-01

    Various custom-made phantoms designed to optimize magnetic resonance imaging (MRI) sequences have been created and subsequently reported in Japanese Society of Radiological Technology (JSRT). However, custom-made phantoms that correctly match the T 1 -value and T 2 -values of human brain tissue (gray matter and white matter) cannot be made easily or quickly. The aim of this project was to search for alternative materials, such as fruits and vegetables, for optimizing MRI sequences. The following eight fruits and vegetables were investigated: apple, tomato, melon, apple mango (Mangifera indica), banana, avocado, peach, and eggplant. Their potential was studied for use in modeling phantoms of normal human brain tissues. MRI (T 1 - and T 2 -weighted sequences) was performed on the human brain and the fruits and vegetables using various concentrations of contrast medium (gadolinium) in the same size tubes as the custom-made phantom. The authors compared the signal intensity (SI) in human brain tissue (gray matter and white matter) with that of the fruits and the custom-made phantom. The T 1 and T 2 values were measured for banana tissue and compared with those for human brain tissue in the literature. Our results indicated that banana tissue is similar to human brain tissue (both gray matter and white matter). Banana tissue can thus be employed as an alternative phantom for the human brain for the purpose of MRI. (author)

  17. Internal strain estimation for quantification of human heel pad elastic modulus: A phantom study.

    Science.gov (United States)

    Holst, Karen; Liebgott, Hervé; Wilhjelm, Jens E; Nikolov, Svetoslav; Torp-Pedersen, Søren T; Delachartre, Philippe; Jensen, Jørgen A

    2013-02-01

    Shock absorption is the most important function of the human heel pad. However, changes in heel pad elasticity, as seen in e.g. long-distance runners, diabetes patients, and victims of Falanga torture are affecting this function, often in a painful manner. Assessment of heel pad elasticity is usually based on one or a few strain measurements obtained by an external load-deformation system. The aim of this study was to develop a technique for quantitative measurements of heel pad elastic modulus based on several internal strain measures from within the heel pad by use of ultrasound images. Nine heel phantoms were manufactured featuring a combination of three heel pad stiffnesses and three heel pad thicknesses to model the normal human variation. Each phantom was tested in an indentation system comprising a 7MHz linear array ultrasound transducer, working as the indentor, and a connected load cell. Load-compression data and ultrasound B-mode images were simultaneously acquired in 19 compression steps of 0.1mm each. The internal tissue displacement was for each step calculated by a phase-based cross-correlation technique and internal strain maps were derived from these displacement maps. Elastic moduli were found from the resulting stress-strain curves. The elastic moduli made it possible to distinguish eight of nine phantoms from each other according to the manufactured stiffness and showed very little dependence of the thickness. Mean elastic moduli for the three soft, the three medium, and the three hard phantoms were 89kPa, 153kPa, and 168kPa, respectively. The combination of ultrasound images and force measurements provided an effective way of assessing the elastic properties of the heel pad due to the internal strain estimation. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom.

    Science.gov (United States)

    Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

    2014-07-01

    To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques.

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

    International Nuclear Information System (INIS)

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

    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 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 counting 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

  20. 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.

  1. Experimental verification of internal dosimetry calculations: Construction of a heterogeneous phantom based on human organs

    International Nuclear Information System (INIS)

    Lauridsen, B.; Hedemann Jensen, P.

    1987-01-01

    The basic dosimetric quantity in ICRP-publication no. 30 is the aborbed fraction AF(T<-S). This parameter is the fraction of energy absorbed in a target organ T per emission of radiation from activity deposited in the source organ S. Based upon this fraction it is possible to calculate the Specific Effective Energy SEE(T<-S). From this, the committed effective dose equivalent from an intake of radioactive material can be found, and thus the annual limit of intake for given radionuclides can be determined. A male phantom has been constructed with the aim of measuring the Specific Effective Energy SEE(T<-S) in various target organs. Impressions-of real human organs have been used to produce vacuum forms. Tissue equivalent plastic sheets were sucked into the vacuum forms producing a shell with a shape identical to the original organ. Each organ has been made of two shells. The same procedure has been used for the body. Thin tubes through the organs make it possible to place TL dose meters in a matrix so the dose distribution can be measured. The phantom has been supplied with lungs, liver, kidneys, spleen, stomach, bladder, pancreas, and thyroid gland. To select a suitable body liquid for the phantom, laboratory experiments have been made with different liquids and different radionuclides. In these experiments the change in dose rate due to changes in density and composition of the liquid was determined. Preliminary results of the experiments are presented. (orig.)

  2. Dedicated mobile volumetric cone-beam computed tomography for human brain imaging: A phantom study.

    Science.gov (United States)

    Ryu, Jong-Hyun; Kim, Tae-Hoon; Jeong, Chang-Won; Jun, Hong-Young; Heo, Dong-Woon; Lee, Jinseok; Kim, Kyong-Woo; Yoon, Kwon-Ha

    2015-01-01

    Mobile computed tomography (CT) with a cone-beam source is increasingly used in the clinical field. Mobile cone-beam CT (CBCT) has great merits; however, its clinical utility for brain imaging has been limited due to problems including scan time and image quality. The aim of this study was to develop a dedicated mobile volumetric CBCT for obtaining brain images, and to optimize the imaging protocol using a brain phantom. The mobile volumetric CBCT system was evaluated with regards to scan time and image quality, measured as signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), spatial resolution (10% MTF), and effective dose. Brain images were obtained using a CT phantom. The CT scan took 5.14 s at 360 projection views. SNR and CNR were 5.67 and 14.5 at 120 kV/10 mA. SNR and CNR values showed slight improvement as the x-ray voltage and current increased (p < 0.001). Effective dose and 10% MTF were 0.92 mSv and 360 μ m at 120 kV/10 mA. Various intracranial structures were clearly visible in the brain phantom images. Using this CBCT under optimal imaging acquisition conditions, it is possible to obtain human brain images with low radiation dose, reproducible image quality, and fast scan time.

  3. 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...

  4. DEEP code to calculate dose equivalents in human phantom for external photon exposure by Monte Carlo method

    International Nuclear Information System (INIS)

    Yamaguchi, Yasuhiro

    1991-01-01

    The present report describes a computer code DEEP which calculates the organ dose equivalents and the effective dose equivalent for external photon exposure by the Monte Carlo method. MORSE-CG, Monte Carlo radiation transport code, is incorporated into the DEEP code to simulate photon transport phenomena in and around a human body. The code treats an anthropomorphic phantom represented by mathematical formulae and user has a choice for the phantom sex: male, female and unisex. The phantom can wear personal dosimeters on it and user can specify their location and dimension. This document includes instruction and sample problem for the code as well as the general description of dose calculation, human phantom and computer code. (author)

  5. Exploratory study on the methodology of fast imaging of unilateral stroke lesions by electrical impedance asymmetry in human heads.

    Science.gov (United States)

    Ma, Jieshi; Xu, Canhua; Dai, Meng; You, Fusheng; Shi, Xuetao; Dong, Xiuzhen; Fu, Feng

    2014-01-01

    Stroke has a high mortality and disability rate and should be rapidly diagnosed to improve prognosis. Diagnosing stroke is not a problem for hospitals with CT, MRI, and other imaging devices but is difficult for community hospitals without these devices. Based on the mechanism that the electrical impedance of the two hemispheres of a normal human head is basically symmetrical and a stroke can alter this symmetry, a fast electrical impedance imaging method called symmetrical electrical impedance tomography (SEIT) is proposed. In this technique, electrical impedance tomography (EIT) data measured from the undamaged craniocerebral hemisphere (CCH) is regarded as reference data for the remaining EIT data measured from the other CCH for difference imaging to identify the differences in resistivity distribution between the two CCHs. The results of SEIT imaging based on simulation data from the 2D human head finite element model and that from the physical phantom of human head verified this method in detection of unilateral stroke.

  6. Impact of patient weight on tumor visibility based on human-shaped phantom simulation study in PET imaging system

    International Nuclear Information System (INIS)

    Musarudin, M.; Saripan, M.I.; Mashohor, S.; Saad, W.H.M.; Nordin, A.J.; Hashim, S.

    2015-01-01

    Energy window technique has been implemented in all positron emission tomography (PET) imaging protocol, with the aim to remove the unwanted low energy photons. Current practices in our institution however are performed by using default energy threshold level regardless of the weight of the patient. Phantom size, which represents the size of the patient's body, is the factor that determined the level of scatter fraction during PET imaging. Thus, the motivation of this study is to determine the optimum energy threshold level for different sizes of human-shaped phantom, to represent underweight, normal, overweight and obese patients. In this study, the scanner was modeled by using Monte Carlo code, version MCNP5. Five different sizes of elliptical-cylinder shaped of human-sized phantoms with diameter ranged from 15 to 30 cm were modeled. The tumor was modeled by a cylindrical line source filled with 1.02 MeV positron emitters at the center of the phantom. Various energy window widths, in the ranged of 10–50% were implemented to the data. In conclusion, the phantom mass volume did influence the scatter fraction within the volume. Bigger phantom caused more scattering events and thus led to coincidence counts lost. We evaluated the impact of phantom sizes on the sensitivity and visibility of the simulated models. Implementation of wider energy window improved the sensitivity of the system and retained the coincidence photons lost. Visibility of the tumor improved as an appropriate energy window implemented for the different sizes of phantom. - Highlights: • Optimizing the energy window improved the sensitivity of the PET system. • Improving the visibility of the tumors using the optimized energy window. • Recommendations on the optimized energy windows for different body sizes. • Using simulated phantom using MCNP to determine various body sizes

  7. Assessment of diffusion tensor image quality across sites and vendors using the American College of Radiology head phantom.

    Science.gov (United States)

    Wang, Zhiyue J; Seo, Youngseob; Babcock, Evelyn; Huang, Hao; Bluml, Stefan; Wisnowski, Jessica; Holshouser, Barbara; Panigrahy, Ashok; Shaw, Dennis W W; Altman, Nolan; McColl, Roderick W; Rollins, Nancy K

    2016-05-08

    The purpose of this study was to explore the feasibility of assessing quality of diffusion tensor imaging (DTI) from multiple sites and vendors using American College of Radiology (ACR) phantom. Participating sites (Siemens (n = 2), GE (n= 2), and Philips (n = 4)) reached consensus on parameters for DTI and used the widely available ACR phantom. Tensor data were processed at one site. B0 and eddy current distortions were assessed using grid line displacement on phantom Slice 5; signal-to-noise ratio (SNR) was measured at the center and periphery of the b = 0 image; fractional anisotropy (FA) and mean diffusivity (MD) were assessed using phantom Slice 7. Variations of acquisition parameters and deviations from specified sequence parameters were recorded. Nonlinear grid line distortion was higher with linear shimming and could be corrected using the 2nd order shimming. Following image registration, eddy current distortion was consistently smaller than acquisi-tion voxel size. SNR was consistently higher in the image periphery than center by a factor of 1.3-2.0. ROI-based FA ranged from 0.007 to 0.024. ROI-based MD ranged from 1.90 × 10-3 to 2.33 × 10-3 mm2/s (median = 2.04 × 10-3 mm2/s). Two sites had image void artifacts. The ACR phantom can be used to compare key qual-ity measures of diffusion images acquired from multiple vendors at multiple sites.

  8. 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...

  9. MO-F-CAMPUS-J-01: 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

    Energy Technology Data Exchange (ETDEWEB)

    Lin, H; Jing, J; Xie, C [Hefei University of Technology, Hefei (China); Lu, Y [Shanghai Jiao Tong University, Shanghai (China)

    2015-06-15

    Purpose: To find effective setting methods to mitigate the irradiation injure in synchrotron radiation microangiography(SRA) by Monte Carlo simulation. Methods: A mouse 1-D head model and a segmented voxel mouse head phantom were simulated by EGSnrc/Dosxyznrc code to investigate the dose enhancement effect of the iodine contrast agent irradiated by a monochromatic synchrotron radiation(SR) source. The influence of, like iodine concentration (IC), vessel width and depth, with and without skull layer protection and the various incident X ray energies, were simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated. Results: The dose enhancement ratio depends little on the irradiation depth, but strongly on the IC, which is linearly increases with IC. The skull layer protection cannot be ignored in SRA, the 700µm thick skull could decrease 10% of the dose. The incident X-ray energy can significantly affact the dose. E.g. compared to the dose of 33.2keV for 50mgI/ml, the 32.7keV dose decreases 38%, whereas the dose of 33.7 keV increases 69.2%, and the variation will strengthen more with enhanced IC. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depends little on the iodine voxel volume ratio, but strongly on IC. Conclusion: To decrease dose damage in SRA, the high-Z contrast agent should be used as little as possible, and try to avoid radiating locally the injected position immediately after the contrast agent injection. The fragile vessel containing iodine should avoid closely irradiating. Avoiding irradiating through the no or thin skull region, or appending thin equivalent material from outside to protect is also a better method. As long as SRA image quality is ensured, using incident X-ray energy as low as possible.

  10. Computer tomographic phantom

    International Nuclear Information System (INIS)

    Lonn, A.H.R.; Jacobsen, D.R.; Zech, D.J.

    1988-01-01

    A reference phantom for computer tomography employs a flexible member with means for urging the flexible member into contact along the curved surface of the lumbar region of a human patient. In one embodiment, the reference phantom is pre-curved in an arc greater than required. Pressure from the weight of a patient laying upon the reference phantom is effective for straightening out the curvature sufficiently to achieve substantial contact along the lumbar region. The curvature of the reference phantom may be additionally distorted by a resilient pad between the resilient phantom and a table for urging it into contact with the lumbar region. In a second embodiment of the invention, a flexible reference phantom is disposed in a slot in the top of a resilient cushion. The resilient cushion and reference phantom may be enclosed in a flexible container. A partially curved reference phantom in a slot in a resilient cushion is also contemplated. (author)

  11. Anne-Sylvie Catherin, Head of the Human Resources Department

    CERN Multimedia

    2009-01-01

    Anne-Sylvie Catherin has been appointed Head of the Human Resources Department with effect from 1 August 2009. Mrs Catherin is a lawyer specialized in International Administration and joined CERN in 1996 as legal advisor within the Office of the HR Department Head. After having been promoted to the position of Group Leader responsible for social and statutory conditions in 2000, Mrs Catherin was appointed Deputy of the Head of the Human Resources Department and Group Leader responsible for Strategy, Management and Development from 2005 to date. Since 2005, she has also served as a member of CCP and TREF. In the execution of her mandate as Deputy HR Department Head, Mrs Catherin closely assisted the HR Department Head in the organization of the Department and in devising new HR policies and strategies. She played an instrumental role in the last five-yearly review and in the revision of the Staff Rules and Regulations.

  12. Influence of different types of phantoms on the calibration of dosemeters for eye lens dosimetry

    International Nuclear Information System (INIS)

    Yoshitomi, H.; Kowatari, M.

    2016-01-01

    Both a cylinder and a slab phantom have been recommended to be used as calibration phantoms for eye lens dosimetry in the International Atomic Energy Agency TECDOC. This study describes investigations on the influence of the type of phantom on the calibration of dosemeters. In order to fulfil the purpose, backscatter radiation from practically used water-filled phantoms was evaluated by calculations and experiments. For photons, the calculations showed that the cylinder phantom had 10 % lower backscattered effect at maximum than a slab phantom, and simulated well the backscattered effect of the human head or neck to within ±10 %. The irradiation results of non-filtered optically stimulated luminescence and radio-photoluminescence glass dosemeters indicated that the differences of the calibration factors between the two types of phantoms were up to 20 and 10 %, respectively, reflecting the response to backscattered photons. For electrons, no difference was found between the two types of phantoms. (authors)

  13. Ion therapy for uveal melanoma in new human eye phantom based on GEANT4 toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Mahdipour, Seyed Ali [Physics Department, Hakim Sabzevari University, Sabzevar (Iran, Islamic Republic of); Mowlavi, Ali Asghar, E-mail: amowlavi@hsu.ac.ir [Physics Department, Hakim Sabzevari University, Sabzevar (Iran, Islamic Republic of); ICTP, Associate Federation Scheme, Medical Physics Field, Trieste (Italy)

    2016-07-01

    Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth−dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8 MeV proton, 190.1 MeV alpha, and 1060 MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam's Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.

  14. Ion therapy for uveal melanoma in new human eye phantom based on GEANT4 toolkit

    International Nuclear Information System (INIS)

    Mahdipour, Seyed Ali; Mowlavi, Ali Asghar

    2016-01-01

    Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth−dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8 MeV proton, 190.1 MeV alpha, and 1060 MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam's Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.

  15. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

    International Nuclear Information System (INIS)

    Könik, Arda; Johnson, Karen L; Dasari, Paul; Pretorius, P H; Dey, Joyoni; King, Michael A; Connolly, Caitlin M; Segars, Paul W; Lindsay, Clifford

    2014-01-01

    The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory

  16. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

    Science.gov (United States)

    Könik, Arda; Connolly, Caitlin M.; Johnson, Karen L.; Dasari, Paul; Segars, Paul W.; Pretorius, P. H.; Lindsay, Clifford; Dey, Joyoni; King, Michael A.

    2014-07-01

    The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory

  17. A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms.

    Science.gov (United States)

    Krueger, Diane; Libber, Jessie; Sanfilippo, Jennifer; Yu, Hui Jing; Horvath, Blaine; Miller, Colin G; Binkley, Neil

    2016-01-01

    New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good BMD and BMC agreement, did not detect

  18. Generation of a suite of 3D computer-generated breast phantoms from a limited set of human subject data

    International Nuclear Information System (INIS)

    Hsu, Christina M. L.; Palmeri, Mark L.; Segars, W. Paul; Veress, Alexander I.; Dobbins, James T. III

    2013-01-01

    Purpose: The authors previously reported on a three-dimensional computer-generated breast phantom, based on empirical human image data, including a realistic finite-element based compression model that was capable of simulating multimodality imaging data. The computerized breast phantoms are a hybrid of two phantom generation techniques, combining empirical breast CT (bCT) data with flexible computer graphics techniques. However, to date, these phantoms have been based on single human subjects. In this paper, the authors report on a new method to generate multiple phantoms, simulating additional subjects from the limited set of original dedicated breast CT data. The authors developed an image morphing technique to construct new phantoms by gradually transitioning between two human subject datasets, with the potential to generate hundreds of additional pseudoindependent phantoms from the limited bCT cases. The authors conducted a preliminary subjective assessment with a limited number of observers (n= 4) to illustrate how realistic the simulated images generated with the pseudoindependent phantoms appeared. Methods: Several mesh-based geometric transformations were developed to generate distorted breast datasets from the original human subject data. Segmented bCT data from two different human subjects were used as the “base” and “target” for morphing. Several combinations of transformations were applied to morph between the “base’ and “target” datasets such as changing the breast shape, rotating the glandular data, and changing the distribution of the glandular tissue. Following the morphing, regions of skin and fat were assigned to the morphed dataset in order to appropriately assign mechanical properties during the compression simulation. The resulting morphed breast was compressed using a finite element algorithm and simulated mammograms were generated using techniques described previously. Sixty-two simulated mammograms, generated from morphing

  19. A dictionary learning approach for human sperm heads classification.

    Science.gov (United States)

    Shaker, Fariba; Monadjemi, S Amirhassan; Alirezaie, Javad; Naghsh-Nilchi, Ahmad Reza

    2017-12-01

    To diagnose infertility in men, semen analysis is conducted in which sperm morphology is one of the factors that are evaluated. Since manual assessment of sperm morphology is time-consuming and subjective, automatic classification methods are being developed. Automatic classification of sperm heads is a complicated task due to the intra-class differences and inter-class similarities of class objects. In this research, a Dictionary Learning (DL) technique is utilized to construct a dictionary of sperm head shapes. This dictionary is used to classify the sperm heads into four different classes. Square patches are extracted from the sperm head images. Columnized patches from each class of sperm are used to learn class-specific dictionaries. The patches from a test image are reconstructed using each class-specific dictionary and the overall reconstruction error for each class is used to select the best matching class. Average accuracy, precision, recall, and F-score are used to evaluate the classification method. The method is evaluated using two publicly available datasets of human sperm head shapes. The proposed DL based method achieved an average accuracy of 92.2% on the HuSHeM dataset, and an average recall of 62% on the SCIAN-MorphoSpermGS dataset. The results show a significant improvement compared to a previously published shape-feature-based method. We have achieved high-performance results. In addition, our proposed approach offers a more balanced classifier in which all four classes are recognized with high precision and recall. In this paper, we use a Dictionary Learning approach in classifying human sperm heads. It is shown that the Dictionary Learning method is far more effective in classifying human sperm heads than classifiers using shape-based features. Also, a dataset of human sperm head shapes is introduced to facilitate future research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Outdoor Urban Propagation Experiment of a Handset MIMO Antenna with a Human Phantom located in a Browsing Stance

    DEFF Research Database (Denmark)

    Yamamoto, Atsushi; Hayashi, Toshiteru; Ogawa, Koichi

    2007-01-01

    Outdoor radio propagation experiments are presented at 2.4 GHz, using a handset MIMO antenna with two monopoles and two planar inverted-F antennas (PIFAs), adjacent to a human phantom in browsing stance. The propagation test was performed in an urban area of a city, which resulted in non lineof...

  1. Effect of inherent misalignment and head motion in neurological PET/MR with the Philips Ingenuity TF – phantom and patient study

    Energy Technology Data Exchange (ETDEWEB)

    Teuho, Jarmo; Johansson, Jarkko; Saunavaara, Virva; Kemppainen, Nina; Teräs, Mika [Turku PET Centre, Turku University Hospital, Turku (Finland)

    2014-07-29

    The aim of the study was to evaluate the effect of misalignment and head motion on image quantification in PET/MR with a novel brain phantom and a healthy control group. The phantom was imaged at two time points in PET/MR, concurrently with PET and PET/CT. Phantom images were evaluated visually and the relative difference in hemispheric accumulation was calculated. Difference in cortical accumulation in a healthy control group was evaluated from non-attenuation corrected (NAC) and MR attenuation corrected (MRAC) images. Regional ROI mean values from F{sup 18}-FDG ratio images and regional hemispheric asymmetries were calculated. Controls were divided to high and low asymmetry groups. A student’s t-test (p<0.005) for group difference and NAC versus MRAC data was performed. Finally, mean PET-MR registration parameters were measured. Only the first phantom scan exhibited asymmetry in lateral frontal cortex (17%) and temporal cortex (19%). Correcting the misalignment of 2.63mm reduced the asymmetry to less than 5%, to a level seen in PET and PET/CT. A significant asymmetry was found in the temporal and parietal cortex between groups in MRAC data with no significant asymmetry in NAC data. Asymmetries in affected MRAC data in temporal and parietal cortex were 9.4% and 11.7%. NAC data from both groups had asymmetry less than 5% in all regions. Both groups had significant y- and z-translation, while only the asymmetry group had significant z-rotation and x-translation. The shift in x-, y-, or z-direction in both groups was less than 4 mm, with no significant differences. Thus, PET-MRAC misalignment may cause under- and overestimation of attenuation in the lines of response on opposite sides of the cortical regions, resulting to asymmetric difference between the hemispheres. Our findings stress the need for novel QC procedures for PET-MR alignment and suggest confirming the quality of PET-MRAC alignment from PET-NAC images.

  2. Experimental validation of deterministic Acuros XB algorithm for IMRT and VMAT dose calculations with the Radiological Physics Center's head and neck phantom

    International Nuclear Information System (INIS)

    Han Tao; Mourtada, Firas; Kisling, Kelly; Mikell, Justin; Followill, David; Howell, Rebecca

    2012-01-01

    Purpose: The purpose of this study was to verify the dosimetric performance of Acuros XB (AXB), a grid-based Boltzmann solver, in intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Methods: The Radiological Physics Center (RPC) head and neck (H and N) phantom was used for all calculations and measurements in this study. Clinically equivalent IMRT and VMAT plans were created on the RPC H and N phantom in the Eclipse treatment planning system (version 10.0) by using RPC dose prescription specifications. The dose distributions were calculated with two different algorithms, AXB 11.0.03 and anisotropic analytical algorithm (AAA) 10.0.24. Two dose report modes of AXB were recorded: dose-to-medium in medium (D m,m ) and dose-to-water in medium (D w,m ). Each treatment plan was delivered to the RPC phantom three times for reproducibility by using a Varian Clinac iX linear accelerator. Absolute point dose and planar dose were measured with thermoluminescent dosimeters (TLDs) and GafChromic registered EBT2 film, respectively. Profile comparison and 2D gamma analysis were used to quantify the agreement between the film measurements and the calculated dose distributions from both AXB and AAA. The computation times for AAA and AXB were also evaluated. Results: Good agreement was observed between measured doses and those calculated with AAA or AXB. Both AAA and AXB calculated doses within 5% of TLD measurements in both the IMRT and VMAT plans. Results of AXB Dm,m (0.1% to 3.6%) were slightly better than AAA (0.2% to 4.6%) or AXB Dw,m (0.3% to 5.1%). The gamma analysis for both AAA and AXB met the RPC 7%/4 mm criteria (over 90% passed), whereas AXB Dm,m met 5%/3 mm criteria in most cases. AAA was 2 to 3 times faster than AXB for IMRT, whereas AXB was 4-6 times faster than AAA for VMAT. Conclusions: AXB was found to be satisfactorily accurate when compared to measurements in the RPC H and N phantom. Compared with AAA, AXB results were equal

  3. Modelling and assessment of the electric field strength caused by mobile phone to the human head.

    Science.gov (United States)

    Buckus, Raimondas; Strukcinskiene, Birute; Raistenskis, Juozas; Stukas, Rimantas

    2016-06-01

    Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. In this paper the software "COMSOL Multiphysics" was used to establish the electric field strength created by mobile phones around the head. The second generation (2G) Global System for Mobile (GSM) phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G) GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G) UMTS smart phones that effectively use high (2,100 MHz) radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear), and constitutes 1-12% of the artificial head's surface. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR) and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user's ear.

  4. SU-E-T-87: Comparison Study of Dose Reconstruction From Cylindrical Diode Array Measurements, with TLD Measurements and Treatment Planning System Calculations in Anthropomorphic Head and Neck and Lung Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Benhabib, S; Cardan, R; Huang, M; Brezovich, I; Popple, R [University of Alabama at Birmingham, Birmingham, AL (United States); Faught, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-01

    Purpose: To assess dose calculated by the 3DVH software (Sun Nuclear Systems, Melbourne, FL) against TLD measurements and treatment planning system calculations in anthropomorphic phantoms. Methods: The IROC Houston (RPC) head and neck (HN) and lung phantoms were scanned and plans were generated using Eclipse (Varian Medical Systems, Milpitas, CA) following IROC Houston procedures. For the H and N phantom, 6 MV VMAT and 9-field dynamic MLC (DMLC) plans were created. For the lung phantom 6 MV VMAT and 15 MV 9-field dynamic MLC (DMLC) plans were created. The plans were delivered to the phantoms and to an ArcCHECK (Sun Nuclear Systems, Melbourne, FL). The head and neck phantom contained 8 TLDs located at PTV1 (4), PTV2 (2), and OAR Cord (2). The lung phantom contained 4 TLDs, 2 in the PTV, 1 in the cord, and 1 in the heart. Daily outputs were recorded before each measurement for correction. 3DVH dose reconstruction software was used to project the calculated dose to patient anatomy. Results: For the HN phantom, the maximum difference between 3DVH and TLDs was -3.4% and between 3DVH and Eclipse was 1.2%. For the lung plan the maximum difference between 3DVH and TLDs was 4.3%, except for the spinal cord for which 3DVH overestimated the TLD dose by 12%. The maximum difference between 3DVH and Eclipse was 0.3%. 3DVH agreed well with Eclipse because the dose reconstruction algorithm uses the diode measurements to perturb the dose calculated by the treatment planning system; therefore, if there is a problem in the modeling or heterogeneity correction, it will be carried through to 3DVH. Conclusion: 3DVH agreed well with Eclipse and TLD measurements. Comparison of 3DVH with film measurements is ongoing. Work supported by PHS grant CA10953 and CA81647 (NCI, DHHS)

  5. Symbol phantoms

    International Nuclear Information System (INIS)

    Yamaguchi, Hiroshi; Hongo, Syozo; Takeshita, Hiroshi

    1990-01-01

    We have developed Japanese phantoms in two procedures for computation of organ doses exposed to internal and/or external radiation sources. One method is to make mathematical phantoms on the basis of ORNL mathematical phantoms. Parameters to specify organs of Japanese mathematical phantom are determined by interpolations of the ORNL data, which define the organs of Caucasian males and females of various ages, i.e. new born, 1, 5, 10, 15 years and adult, with survey data for Japanese physiques. Another procedure is to build 'symbol phantoms' for the Japanese public. The concept and its method of the symbol phantom enables us to make a phantom for an individual when we have all of his transversal section images obtained by a medical imaging device like MRI, and thus we may achieve more realistic phantoms for Japanese public than the mathematical phantoms. Both studies are in progress in NIRS. (author)

  6. 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.

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

    International Nuclear Information System (INIS)

    Cassola, V F; Kramer, R; Khoury, H J; De Melo Lima, V 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 A M and female RPI A F phantoms shows differences with respect to the material used, to the software and concepts applied, and to the anatomies created.

  8. Electromagnetic field effect simulation over a realistic pixel ed phantom human's brain

    International Nuclear Information System (INIS)

    Rojas, R.; Calderon, J. A.; Rivera, T.; Azorin, J.

    2012-10-01

    The exposition to different types of electromagnetic radiations can produce damages and injures on the people's tissues. The scientist, spend time and resources studying the effects of electromagnetic fields over the organs. Particularly in medical areas, the specialist in imaging methodologies and radiological treatment, are very worried about no injure there patient. Determination of matter radiation interaction, can be experimental or theoretical is not an easy task anyway. At first case, is not possible make measures inside the patient, then the experimental procedure consist in make measures in human's dummy, however, is not possible see deformations of electromagnetic fields due the organs presence. In the second case, is necessary solve, the Maxwell's equations with the electromagnetic field, crossing a lot of organs and tissues with different electric and magnetic properties each one. One alternative for theoretical solution, is make a computational simulation, however, this option, require an enormous quantity of memory and large computational times. Then, the most simulations are making in 2 dimensional or in 3 dimensional although using human models approximations, build ed with basic geometrical figures, like spheres, cylinders, ellipsoids, etc. Obviously this models just lets obtain a coarse solution of the actually situation. In this work, we propose a novel methodology to build a realistic pixel ed phantom of human's organs, and solve the Maxwell's equations over this models, evidently, the solutions are more approximated to the real behaviour. Additionally, there models results optimized when they are discretized and the finite element method is used to calculate the electromagnetic field and the induced currents. (Author)

  9. Electromagnetic field effect simulation over a realistic pixel ed phantom human's brain

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, R.; Calderon, J. A.; Rivera, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Calz. Legaria No. 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Azorin, J., E-mail: rafaelturing@prodigy.net.mx [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)

    2012-10-15

    The exposition to different types of electromagnetic radiations can produce damages and injures on the people's tissues. The scientist, spend time and resources studying the effects of electromagnetic fields over the organs. Particularly in medical areas, the specialist in imaging methodologies and radiological treatment, are very worried about no injure there patient. Determination of matter radiation interaction, can be experimental or theoretical is not an easy task anyway. At first case, is not possible make measures inside the patient, then the experimental procedure consist in make measures in human's dummy, however, is not possible see deformations of electromagnetic fields due the organs presence. In the second case, is necessary solve, the Maxwell's equations with the electromagnetic field, crossing a lot of organs and tissues with different electric and magnetic properties each one. One alternative for theoretical solution, is make a computational simulation, however, this option, require an enormous quantity of memory and large computational times. Then, the most simulations are making in 2 dimensional or in 3 dimensional although using human models approximations, build ed with basic geometrical figures, like spheres, cylinders, ellipsoids, etc. Obviously this models just lets obtain a coarse solution of the actually situation. In this work, we propose a novel methodology to build a realistic pixel ed phantom of human's organs, and solve the Maxwell's equations over this models, evidently, the solutions are more approximated to the real behaviour. Additionally, there models results optimized when they are discretized and the finite element method is used to calculate the electromagnetic field and the induced currents. (Author)

  10. Blood flow and microdialysis in the human femoral head

    DEFF Research Database (Denmark)

    Bøgehøj, Morten; Emmeluth, Claus; Overgaard, Søren

    2007-01-01

    BACKGROUND: If it would be possible to detect lack of flow and/or the development of ischemia in bone, we might have a way of predicting whether a broken bone will heal. We established microdialysis (MD) and laser Doppler (LD) flow measurement in the human femoral head in order to be able to detect...

  11. Dosimetric Comparison of Simulated Human Eye And Water Phantom in Investigation of Iodine Source Effects on Tumour And Healthy Tissues

    International Nuclear Information System (INIS)

    Sadi, A.S.; Masoudi, F.S. K.N.Toosi University of Technology

    2011-01-01

    For better clinical analysis in ophthalmic brachytherapy dosimetry, there is a need for the dose determination in different parts of the eye, so simulating the eye and defining the material of any parts of that, is helpful for better investigating dosimetry in human eye. However in brachytherapy dosimetry, it is common to consider the water phantom as human eye globe. In this work, a full human eye is simulated with MCNP-4C code by considering all parts of the eye like; lens, cornea, retina, choroid, sclera, anterior chamber, optic nerve, bulk of the eye comprising vitreous body and tumour. The average dose in different parts of this full model of human eye is determined and the results are compared with the dose calculated in water phantom. The central axes depth dose and the dose in whole of the tumour for these two simulated eye model are calculated too, and the results are compared. At long last, as the aim of this work is comparing the result of investigating dosimetry between two water phantom as human eye and simulated eye globe, the ratios of the absorbed dose by the healthy tissues to the absorbed dose by the tumour are calculated in these simulations and the comparison between results is done eventually.

  12. Enrico Chiaveri, new Head of the Human Resources Department

    CERN Document Server

    2005-01-01

    Enrico Chiaveri has been appointed Head of the Human Resources Department of with effect from 1st April 2005. A senior physicist, Dr Chiaveri joined CERN in 1973. During his career, he has performed various management roles, including that of Deputy Leader of the SPS/LEP Division, and has acquired extensive experience in human resources matters. Over the transition period up to 1st August 2005 he will gradually relinquish his current functions as Group Leader within the AB Department.

  13. SU-F-BRE-04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

    International Nuclear Information System (INIS)

    Ehler, E; Higgins, P; Dusenbery, K

    2014-01-01

    Purpose: To validate a method to create per patient phantoms for dosimetric verification measurements. Methods: Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in-vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel-opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On-board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation. Results: The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index). Conclusion: A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom

  14. SU-F-BRE-04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ehler, E; Higgins, P; Dusenbery, K [University of Minnesota, Minneapolis, MN (United States)

    2014-06-15

    Purpose: To validate a method to create per patient phantoms for dosimetric verification measurements. Methods: Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in-vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel-opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On-board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation. Results: The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index). Conclusion: A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom.

  15. PID - 3D: a software to develop mathematical human phantoms for use in computational dosimetry

    International Nuclear Information System (INIS)

    Lima Filho, Jose de Melo; Vieira, Jose Wilson; Lima, Vanildo Junior de Melo; Lima, Fernando Roberto de Andrade

    2009-01-01

    The PID-3D software, written in Visual C++, contains tools developed for building and editing of three-dimensional geometric figures formed of voxels (volume pixels). These tools were projected to be used, together with those already developed by the Grupo de Dosimetria Numerica (GDN/CNPq), such as the FANTOMAS and DIP software, in computational dosimetry of ionizing radiation. The main objective of this paper is to develop various voxel-based geometric solids to build voxel phantoms (meaning models), anthropomorphic or not. The domain of this technique of development of geometric solids is important for the GDN/CNPq, because it allows the use of just one Monte Carlo code to simulate the transportation, interaction and deposition of radiation in tomographic and mathematical phantoms. Building a particular geometric solid the user needs to inform to the PID-3D software, the location and the size of the parallelepiped that involves it. Each built solid can be saved in a binary file of the type SGI (file containing the size and the numeric values that constitutes the 3D matrix that represents the solid, commonly used by GDN/CNPq). The final mathematical phantom is built starting from these SGI files and the SGI file resulting constitutes a voxel phantom. With this approach the software's user does not have to manipulate the equations and inequalities of the solids that represent the organs and tissues of the phantom. The 3D-PID software, associated with the FANTOMAS and DIP software are tools produced by GDN/CNPq, providing a new technique for building of 3D scenes in dosimetric evaluations using voxel phantoms. To validate the PID-3D software one built, step by step, a phantom similar to the MIRD-5 stylized phantom. (author)

  16. Determination of the distal dose edge in a human phantom by measuring the prompt gamma distribution: a Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Min, Chul Hee; Lee, Han Rim; Yeom, Yeon Su; Cho, Sung Koo; Kim, Chan Hyeong [Hanyang University, Seoul (Korea, Republic of)

    2010-06-15

    The close relationship between the proton dose distribution and the distribution of prompt gammas generated by proton-induced nuclear interactions along the path of protons in a water phantom was demonstrated by means of both Monte Carlo simulations and limited experiments. In order to test the clinical applicability of the method for determining the distal dose edge in a human body, a human voxel model, constructed based on a body-composition-approximated physical phantom, was used, after which the MCNPX code was used to analyze the energy spectra and the prompt gamma yields from the major elements composing the human voxel model; finally, the prompt gamma distribution, generated from the voxel model and measured by using an array-type prompt gamma detection system, was calculated and compared with the proton dose distribution. According to the results, effective prompt gammas were produced mainly by oxygen, and the specific energy of the prompt gammas, allowing for selective measurement, was found to be 4.44 MeV. The results also show that the distal dose edge in the human phantom, despite the heterogeneous composition and the complicated shape, can be determined by measuring the prompt gamma distribution with an array-type detection system.

  17. Modelling and assessment of the electric field strength caused by mobile phone to the human head

    Directory of Open Access Journals (Sweden)

    Buckus Raimondas

    2016-01-01

    Full Text Available Background/Aim. Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. Methods. In this paper the software “COMSOL Multiphysics” was used to establish the electric field strength created by mobile phones around the head. Results. The second generation (2G Global System for Mobile (GSM phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G UMTS smart phones that effectively use high (2,100 MHz radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear, and constitutes 1-12% of the artificial head’s surface. Conclusion. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user ear.

  18. Effects of External Loads on Human Head Movement Control Systems

    Science.gov (United States)

    Nam, M. H.; Choi, O. M.

    1984-01-01

    The central and reflexive control strategies underlying movements were elucidated by studying the effects of external loads on human head movement control systems. Some experimental results are presented on dynamic changes weigh the addition of aviation helmet (SPH4) and lead weights (6 kg). Intended time-optimal movements, their dynamics and electromyographic activity of neck muscles in normal movements, and also in movements made with external weights applied to the head were measured. It was observed that, when the external loads were added, the subject went through complex adapting processes and the head movement trajectory and its derivatives reached steady conditions only after transient adapting period. The steady adapted state was reached after 15 to 20 seconds (i.e., 5 to 6 movements).

  19. WE-D-303-01: Development and Application of Digital Human Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Segars, P. [Duke University, Durham, NC (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.

  20. WE-D-303-01: Development and Application of Digital Human Phantoms

    International Nuclear Information System (INIS)

    Segars, P.

    2015-01-01

    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

  1. Animation of 3D Model of Human Head

    Directory of Open Access Journals (Sweden)

    V. Michalcin

    2007-04-01

    Full Text Available The paper deals with the new algorithm of animation of 3D model of the human head in combination with its global motion. The designed algorithm is very fast and with low calculation requirements, because it does not need the synthesis of the input videosequence for estimation of the animation parameters as well as the parameters of global motion. The used 3D model Candide generates different expressions using its animation units which are controlled by the animation parameters. These ones are estimated on the basis of optical flow without the need of extracting of the feature points in the frames of the input videosequence because they are given by the selected vertices of the animation units of the calibrated 3D model Candide. The established multiple iterations inside the designed animation algorithm of 3D model of the human head between two successive frames significantly improved its accuracy above all for the large motion.

  2. Design and optimization of a beam shaping assembly for BNCT based on D-T neutron generator and dose evaluation using a simulated head phantom.

    Science.gov (United States)

    Rasouli, Fatemeh S; Masoudi, S Farhad

    2012-12-01

    A feasibility study was conducted to design a beam shaping assembly for BNCT based on D-T neutron generator. The optimization of this configuration has been realized in different steps. This proposed system consists of metallic uranium as neutron multiplier, TiF(3) and Al(2)O(3) as moderators, Pb as reflector, Ni as shield and Li-Poly as collimator to guide neutrons toward the patient position. The in-air parameters recommended by IAEA were assessed for this proposed configuration without using any filters which enables us to have a high epithermal neutron flux at the beam port. Also a simulated Snyder head phantom was used to evaluate dose profiles due to the irradiation of designed beam. The dose evaluation results and depth-dose curves show that the neutron beam designed in this work is effective for deep-seated brain tumor treatments even with D-T neutron generator with a neutron yield of 2.4×10(12) n/s. The Monte Carlo Code MCNP-4C is used in order to perform these calculations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Subchondral bone density distribution in the human femoral head

    Energy Technology Data Exchange (ETDEWEB)

    Wright, David A.; Meguid, Michael; Lubovsky, Omri; Whyne, Cari M. [Sunnybrook Research Institute, Orthopaedic Biomechanics Laboratory, Toronto, Ontario (Canada)

    2012-06-15

    This study aims to quantitatively characterize the distribution of subchondral bone density across the human femoral head using a computed tomography derived measurement of bone density and a common reference coordinate system. Femoral head surfaces were created bilaterally for 30 patients (14 males, 16 females, mean age 67.2 years) through semi-automatic segmentation of reconstructed CT data and used to map bone density, by shrinking them into the subchondral bone and averaging the greyscale values (linearly related to bone density) within 5 mm of the articular surface. Density maps were then oriented with the center of the head at the origin, the femoral mechanical axis (FMA) aligned with the vertical, and the posterior condylar axis (PCA) aligned with the horizontal. Twelve regions were created by dividing the density maps into three concentric rings at increments of 30 from the horizontal, then splitting into four quadrants along the anterior-posterior and medial-lateral axes. Mean values for each region were compared using repeated measures ANOVA and a Bonferroni post hoc test, and side-to-side correlations were analyzed using a Pearson's correlation. The regions representing the medial side of the femoral head's superior portion were found to have significantly higher densities compared to other regions (p < 0.05). Significant side-to-side correlations were found for all regions (r {sup 2} = 0.81 to r {sup 2} = 0.16), with strong correlations for the highest density regions. Side-to-side differences in measured bone density were seen for two regions in the anterio-lateral portion of the femoral head (p < 0.05). The high correlation found between the left and right sides indicates that this tool may be useful for understanding 'normal' density patterns in hips affected by unilateral pathologies such as avascular necrosis, fracture, developmental dysplasia of the hip, Perthes disease, and slipped capital femoral head epiphysis. (orig.)

  4. Application of phantoms of the human body for solving radiation protection problems

    International Nuclear Information System (INIS)

    Poulheim, K.F.; Steuer, J.; Fasten, C.

    1977-01-01

    In order to assess the usefulness of various materials (such as polystyrene, crystal sugar and ethanol) as phantom materials for the mean soft tissue, the lung and the skeleton of the ICRP Reference Man, the linear attenuation coefficients for 20, 60, 100 and 134 keV photons have been calculated using an empirical formula. Furthermore, the design and properties of the phantoms used in the Staatliches Amt fuer Atomsicherheit und Strahlenschutz der DDR (SAAS) for calibration and training purposes have been described including some examples of application. (author)

  5. Effective dose evaluation of NORM-added consumer products using Monte Carlo simulations and the ICRP computational human phantoms

    International Nuclear Information System (INIS)

    Lee, Hyun Cheol; Yoo, Do Hyeon; Testa, Mauro; Shin, Wook-Geun; Choi, Hyun Joon; Ha, Wi-Ho; Yoo, Jaeryong; Yoon, Seokwon; Min, Chul Hee

    2016-01-01

    The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1 mSv y"−"1 for 44 products. It was demonstrated that NORM-added consumer products could be quantitatively assessed for the safety regulation. - Highlights: • Consumer products considered that NORM would be included should be regulated. • 44 products were collected and its gamma activities were measured with HPGe detector. • Through Monte Carlo simulation, organ equivalent doses and effective doses on human phantom were calculated. • All annual effective doses for the products were evaluated as lower than dose limit for the public.

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

    International Nuclear Information System (INIS)

    Lee, Choonsik; Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna; Williams, Jonathan L; Bolch, Wesley E

    2010-01-01

    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

  7. Probabilistic Mapping of Human Visual Attention from Head Pose Estimation

    Directory of Open Access Journals (Sweden)

    Andrea Veronese

    2017-10-01

    Full Text Available Effective interaction between a human and a robot requires the bidirectional perception and interpretation of actions and behavior. While actions can be identified as a directly observable activity, this might not be sufficient to deduce actions in a scene. For example, orienting our face toward a book might suggest the action toward “reading.” For a human observer, this deduction requires the direction of gaze, the object identified as a book and the intersection between gaze and book. With this in mind, we aim to estimate and map human visual attention as directed to a scene, and assess how this relates to the detection of objects and their related actions. In particular, we consider human head pose as measurement to infer the attention of a human engaged in a task and study which prior knowledge should be included in such a detection system. In a user study, we show the successful detection of attention to objects in a typical office task scenario (i.e., reading, working with a computer, studying an object. Our system requires a single external RGB camera for head pose measurements and a pre-recorded 3D point cloud of the environment.

  8. The estimation of 3D SAR distributions in the human head from mobile phone compliance testing data for epidemiological studies

    International Nuclear Information System (INIS)

    Wake, Kanako; Watanabe, Soichi; Taki, Masao; Varsier, Nadege; Wiart, Joe; Mann, Simon; Deltour, Isabelle; Cardis, Elisabeth

    2009-01-01

    A worldwide epidemiological study called 'INTERPHONE' has been conducted to estimate the hypothetical relationship between brain tumors and mobile phone use. In this study, we proposed a method to estimate 3D distribution of the specific absorption rate (SAR) in the human head due to mobile phone use to provide the exposure gradient for epidemiological studies. 3D SAR distributions due to exposure to an electromagnetic field from mobile phones are estimated from mobile phone compliance testing data for actual devices. The data for compliance testing are measured only on the surface in the region near the device and in a small 3D region around the maximum on the surface in a homogeneous phantom with a specific shape. The method includes an interpolation/extrapolation and a head shape conversion. With the interpolation/extrapolation, SAR distributions in the whole head are estimated from the limited measured data. 3D SAR distributions in the numerical head models, where the tumor location is identified in the epidemiological studies, are obtained from measured SAR data with the head shape conversion by projection. Validation of the proposed method was performed experimentally and numerically. It was confirmed that the proposed method provided good estimation of 3D SAR distribution in the head, especially in the brain, which is the tissue of major interest in epidemiological studies. We conclude that it is possible to estimate 3D SAR distributions in a realistic head model from the data obtained by compliance testing measurements to provide a measure for the exposure gradient in specific locations of the brain for the purpose of exposure assessment in epidemiological studies. The proposed method has been used in several studies in the INTERPHONE.

  9. Experimental study on tissue phantoms to understand the effect of injury and suturing on human skin mechanical properties.

    Science.gov (United States)

    Chanda, Arnab; Unnikrishnan, Vinu; Flynn, Zachary; Lackey, Kim

    2017-01-01

    Skin injuries are the most common type of injuries occurring in day-to-day life. A skin injury usually manifests itself in the form of a wound or a cut. While a shallow wound may heal by itself within a short time, deep wounds require surgical interventions such as suturing for timely healing. To date, suturing practices are based on a surgeon's experience and may vary widely from one situation to another. Understanding the mechanics of wound closure and suturing of the skin is crucial to improve clinical suturing practices and also to plan automated robotic surgeries. In the literature, phenomenological two-dimensional computational skin models have been developed to study the mechanics of wound closure. Additionally, the effect of skin pre-stress (due to the natural tension of the skin) on wound closure mechanics has been studied. However, in most of these analyses, idealistic two-dimensional skin geometries, materials and loads have been assumed, which are far from reality, and would clearly generate inaccurate quantitative results. In this work, for the first time, a biofidelic human skin tissue phantom was developed using a two-part silicone material. A wound was created on the phantom material and sutures were placed to close the wound. Uniaxial mechanical tests were carried out on the phantom specimens to study the effect of varying wound size, quantity, suture and pre-stress on the mechanical behavior of human skin. Also, the average mechanical behavior of the human skin surrogate was characterized using hyperelastic material models, in the presence of a wound and sutures. To date, such a robust experimental study on the effect of injury and sutures on human skin mechanics has not been attempted. The results of this novel investigation will provide important guidelines for surgical planning and validation of results from computational models in the future.

  10. Antenna modeling considerations for accurate SAR calculations in human phantoms in close proximity to GSM cellular base station antennas.

    Science.gov (United States)

    van Wyk, Marnus J; Bingle, Marianne; Meyer, Frans J C

    2005-09-01

    International bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute for Electrical and Electronic Engineering (IEEE) make provision for human exposure assessment based on SAR calculations (or measurements) and basic restrictions. In the case of base station exposure this is mostly applicable to occupational exposure scenarios in the very near field of these antennas where the conservative reference level criteria could be unnecessarily restrictive. This study presents a variety of critical aspects that need to be considered when calculating SAR in a human body close to a mobile phone base station antenna. A hybrid FEM/MoM technique is proposed as a suitable numerical method to obtain accurate results. The verification of the FEM/MoM implementation has been presented in a previous publication; the focus of this study is an investigation into the detail that must be included in a numerical model of the antenna, to accurately represent the real-world scenario. This is accomplished by comparing numerical results to measurements for a generic GSM base station antenna and appropriate, representative canonical and human phantoms. The results show that it is critical to take the disturbance effect of the human phantom (a large conductive body) on the base station antenna into account when the antenna-phantom spacing is less than 300 mm. For these small spacings, the antenna structure must be modeled in detail. The conclusion is that it is feasible to calculate, using the proposed techniques and methodology, accurate occupational compliance zones around base station antennas based on a SAR profile and basic restriction guidelines. (c) 2005 Wiley-Liss, Inc.

  11. Application of the method of phantom experimental simulation for evaluation of tissue doses for the Ukrytie object personnel at the Chernobyl' NPP

    International Nuclear Information System (INIS)

    Shcherbina, V.G.; Kochetkov, O.A.; Sokolova, I.K.; Timofeev, L.B.; Ponomarev, V.N.; Drabkin, Yu.A.; Tsov'yanov, A.G.; Panfilenko, V.I.

    1992-01-01

    It is suggested to use the method of experimental phantom simulation when solving the problem of minimization of personnel external irradiation dose loading. The method discussed gives an opportunity to obtain information on dose distributions on surface, inside human body and data on dose loading for individual organs of a human organism. The phantoms, which are used for determination of the laws of external irradiation dose distribution of several positions of the machine room of the fourth unit Ukrytie object, are described. The scheme of the phantom arrangement and the values of does in organism of the human head phantom are given. 6 refs.; 7 figs.; 2 tabs

  12. Performance of cone-beam computed tomography and multidetector computed tomography in diagnostic imaging of the midface: A comparative study on Phantom and cadaver head scans

    Energy Technology Data Exchange (ETDEWEB)

    Veldhoen, Simon [University Medical Center Hamburg, Department of Diagnostic and Interventional Radiology, Hamburg (Germany); University Hospital Wuerzburg, Department of Diagnostic and Interventional Radiology, Wuerzburg (Germany); Schoellchen, Maximilian; Hanken, H.; Precht, C.; Heiland, M. [University Medical Center Hamburg, Department of Oral- and Maxillofacial Surgery, Hamburg (Germany); Henes, F.O.; Adam, G.; Regier, M. [University Medical Center Hamburg, Department of Diagnostic and Interventional Radiology, Hamburg (Germany); Schoen, G. [University Medical Center Hamburg, Department of Medical Biometry and Epidemiology, Hamburg (Germany); Nagel, H.D. [Science and Technology for Radiology, Buchholz (Germany); Schumacher, U. [University Medical Center Hamburg, Institute of Anatomy, Hamburg (Germany)

    2017-02-15

    To compare multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) regarding radiation, resolution, image noise, and image quality. CBCT and 256-MDCT were compared based on three scan protocols: Standard-dose (∼24 mGy), reduced-dose (∼9 mGy), and low-dose (∼4 mGy). MDCT images were acquired in standard- and high-resolution mode (HR-MDCT) and reconstructed using filtered back projection (FBP) and iterative reconstruction (IR). Spatial resolution in linepairs (lp) and objective image noise (OIN) were assessed using dedicated phantoms. Image quality was assessed in scans of 25 cadaver heads using a Likert scale. OIN was markedly higher in FBP-MDCT when compared to CBCT. IR lowered the OIN to comparable values in standard-mode MDCT only. CBCT provided a resolution of 13 lp/cm at standard-dose and 11 lp/cm at reduced-dose vs. 11 lp/cm and 10 lp/cm in HR-MDCT. Resolution of 10 lp/cm was observed for both devices using low-dose settings. Quality scores of MDCT and CBCT did not differ at standard-dose (CBCT, 3.4; MDCT, 3.3-3.5; p > 0.05). Using reduced- and low-dose protocols, CBCT was superior (reduced-dose, 3.2 vs. 2.8; low dose, 3.0 vs. 2.3; p < 0.001). Using the low-dose protocol, the assessed CBCT provided better objective and subjective image quality and equality in resolution. Similar image quality, but better resolution using CBCT was observed at higher exposure settings. (orig.)

  13. 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

    Purpose: To calculate absorbed doses due to neutrons in 87 organs/tissues for anthropomorphic phantoms, irradiated in position supine (head first into the gantry) with orientations anteroposterior (AP) and right-left (RLAT) with a 18 MV accelerator. Conversion factors from monitor units to {mu}Gy per neutron in organs, equivalent doses in organs/tissues, and effective doses, which permit to quantify stochastic risks, are estimated. Methods: MAX06 and FAX06 phantoms were modeled with MCNPX and irradiated with a 18 MV Varian Clinac 2100C/D accelerator whose geometry included a multileaf collimator. Two actual fields of a pelvic treatment were simulated using electron-photon-neutron coupled transport. Absorbed doses due to neutrons were estimated from kerma. Equivalent doses were estimated using the radiation weighting factor corresponding to an average incident neutron energy 0.47 MeV. Statistical uncertainties associated to absorbed doses, as calculated by MCNPX, were also obtained. Results: Largest doses were absorbed in shallowest (with respect to the neutron pathway) organs. In {mu}GyMU{sup -1}, values of 2.66 (for penis) and 2.33 (for testes) were found in MAX06, and 1.68 (for breasts), 1.05 (for lenses of eyes), and 0.94 (for sublingual salivary glands) in FAX06, in AP orientation. In RLAT, the largest doses were found for bone tissues (leg) just at the entrance of the beam in the body (right side in our case). Values, in {mu}GyMU{sup -1}, of 1.09 in upper leg bone right spongiosa, for MAX06, and 0.63 in mandible spongiosa, for FAX06, were found. Except for gonads, liver, and stomach wall, equivalent doses found for FAX06 were, in both orientations, higher than for MAX06. Equivalent doses in AP are higher than in RLAT for all organs/tissues other than brain and liver. Effective doses of 12.6 and 4.1 {mu}SvMU{sup -1} were found for AP and RLAT, respectively. The organs/tissues with larger relative contributions to the effective dose were testes and breasts, in

  14. Human papilloma virus infection in head and neck cancer.

    Science.gov (United States)

    Tribius, Silke; Hoffmann, Markus

    2013-03-01

    The causal link between cervical cancer and human papilloma virus (HPV) is well known. It is now becoming clear that some types of squamous-cell carcinoma of the head and neck, particularly oropharyngeal carcinoma (OPC), are also linked to HPV infection. The development of vaccines against certain HPV genotypes has changed the management strategy for HPV-associated diseases of the uterine cervix. An analogous approach is now being considered for the prevention of HPV-associated diseases of the head and neck. We review pertinent articles retrieved by a selective search of the literature for phase II and III trials providing evidence about a possible effect of HPV status on the survival rates of patients with OPC. Seven trials fulfilled our search criteria: four phase III trials with retrospective HPV analysis and three phase II trials with retrospective and prospective HPV analysis. Patients with HPV-positive OPC survive significantly longer than those with HPV-negative OPC. Tobacco smoking has been identified as a negative prognostic factor in patients with either HPV-negative or HPV-positive disease. The established treatment strategy for OPC in patients with and without the traditional risk factors (tobacco and alcohol consumption) is now being reconsidered in the light of what we have learned about the role of HPV infection. Ongoing and projected clinical trials with risk-factor stratification may soon lead to changes in treatment. Further study is needed to answer the question whether HPV infection in the head and neck region is carcinogenic.

  15. Lesion detection and quantification performance of the Tachyon-I time-of-flight PET scanner: phantom and human studies

    Science.gov (United States)

    Zhang, Xuezhu; Peng, Qiyu; Zhou, Jian; Huber, Jennifer S.; Moses, William W.; Qi, Jinyi

    2018-03-01

    The first generation Tachyon PET (Tachyon-I) is a demonstration single-ring PET scanner that reaches a coincidence timing resolution of 314 ps using LSO scintillator crystals coupled to conventional photomultiplier tubes. The objective of this study was to quantify the improvement in both lesion detection and quantification performance resulting from the improved time-of-flight (TOF) capability of the Tachyon-I scanner. We developed a quantitative TOF image reconstruction method for the Tachyon-I and evaluated its TOF gain for lesion detection and quantification. Scans of either a standard NEMA torso phantom or healthy volunteers were used as the normal background data. Separately scanned point source and sphere data were superimposed onto the phantom or human data after accounting for the object attenuation. We used the bootstrap method to generate multiple independent noisy datasets with and without a lesion present. The signal-to-noise ratio (SNR) of a channelized hotelling observer (CHO) was calculated for each lesion size and location combination to evaluate the lesion detection performance. The bias versus standard deviation trade-off of each lesion uptake was also calculated to evaluate the quantification performance. The resulting CHO-SNR measurements showed improved performance in lesion detection with better timing resolution. The detection performance was also dependent on the lesion size and location, in addition to the background object size and shape. The results of bias versus noise trade-off showed that the noise (standard deviation) reduction ratio was about 1.1–1.3 over the TOF 500 ps and 1.5–1.9 over the non-TOF modes, similar to the SNR gains for lesion detection. In conclusion, this Tachyon-I PET study demonstrated the benefit of improved time-of-flight capability on lesion detection and ROI quantification for both phantom and human subjects.

  16. The properties of human body phantoms used in calculations of electromagnetic fields exposure by wireless communication handsets or hand-operated industrial devices.

    Science.gov (United States)

    Zradziński, Patryk

    2013-06-01

    According to international guidelines, the assessment of biophysical effects of exposure to electromagnetic fields (EMF) generated by hand-operated sources needs the evaluation of induced electric field (E(in)) or specific energy absorption rate (SAR) caused by EMF inside a worker's body and is usually done by the numerical simulations with different protocols applied to these two exposure cases. The crucial element of these simulations is the numerical phantom of the human body. Procedures of E(in) and SAR evaluation due to compliance analysis with exposure limits have been defined in Institute of Electrical and Electronics Engineers standards and International Commission on Non-Ionizing Radiation Protection guidelines, but a detailed specification of human body phantoms has not been described. An analysis of the properties of over 30 human body numerical phantoms was performed which has been used in recently published investigations related to the assessment of EMF exposure by various sources. The differences in applicability of these phantoms in the evaluation of E(in) and SAR while operating industrial devices and SAR while using mobile communication handsets are discussed. The whole human body numerical phantom dimensions, posture, spatial resolution and electric contact with the ground constitute the key parameters in modeling the exposure related to industrial devices, while modeling the exposure from mobile communication handsets, which needs only to represent the exposed part of the human body nearest to the handset, mainly depends on spatial resolution of the phantom. The specification and standardization of these parameters of numerical human body phantoms are key requirements to achieve comparable and reliable results from numerical simulations carried out for compliance analysis against exposure limits or within the exposure assessment in EMF-related epidemiological studies.

  17. SU-F-J-174: A Series of Computational Human Phantoms in DICOM-RT Format for Normal Tissue Dose Reconstruction in Epidemiological Studies

    International Nuclear Information System (INIS)

    Pyakuryal, A; Moroz, B; Lee, C; Pelletier, C; Jung, J; Lee, C

    2016-01-01

    Purpose: Epidemiological studies of second cancer risk in radiotherapy patients often require individualized dose estimates of normal tissues. Prior to 3D conformal radiation therapy planning, patient anatomy information was mostly limited to 2D radiological images or not even available. Generic patient CT images are often used in commercial radiotherapy treatment planning system (TPS) to reconstruct normal tissue doses. The objective of the current work was to develop a series of reference size computational human phantoms in DICOM-RT format for direct use in dose reconstruction in TPS. Methods: Contours of 93 organs and tissues were extracted from a series of pediatric and adult hybrid computational human phantoms (newborn, 1-, 5-, 10-, 15-year-old, and adult males and females) using Rhinoceros software. A MATLAB script was created to convert the contours into the DICOM-RT structure format. The simulated CT images with the resolution of 1×1×3 mm3 were also generated from the binary phantom format and coupled with the DICOM-structure files. Accurate volumes of the organs were drawn in the format using precise delineation of the contours in converted format. Due to complex geometry of organs, higher resolution (1×1×1 mm3) was found to be more efficient in the conversion of newborn and 1-year-old phantoms. Results: Contour sets were efficiently converted into DICOM-RT structures in relatively short time (about 30 minutes for each phantom). A good agreement was observed in the volumes between the original phantoms and the converted contours for large organs (NRMSD<1.0%) and small organs (NRMSD<7.7%). Conclusion: A comprehensive series of computational human phantoms in DICOM-RT format was created to support epidemiological studies of second cancer risks in radiotherapy patients. We confirmed the DICOM-RT phantoms were successfully imported into the TPS programs of major vendors.

  18. TH-AB-209-12: Tissue Equivalent Phantom with Excised Human Tissue for Assessing Clinical Capabilities of Coherent Scatter Imaging Applications

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, K; Morris, R; Spencer, J [Medical Physics Graduate Program, Duke University, Durham, NC (United States); Greenberg, J [Dept. of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Kapadia, A [Carl E Ravin Advanced Imaging Laboratories, Durham, NC (United States)

    2016-06-15

    Purpose: Previously we reported the development of anthropomorphic tissue-equivalent scatter phantoms of the human breast. Here we present the first results from the scatter imaging of the tissue equivalent breast phantoms for breast cancer diagnosis. Methods: A breast phantom was designed to assess the capability of coded aperture coherent x-ray scatter imaging to classify different types of breast tissue (adipose, fibroglandular, tumor). The phantom geometry was obtained from a prone breast geometry scanned on a dedicated breast CT system. The phantom was 3D printed using the segmented DICOM breast CT data. The 3D breast phantom was filled with lard (as a surrogate for adipose tissue) and scanned in different geometries alongside excised human breast tissues (obtained from lumpectomy and mastectomy procedures). The raw data were reconstructed using a model-based reconstruction algorithm and yielded the location and form factor (i.e., momentum transfer (q) spectrum) of the materials that were imaged. The measured material form factors were then compared to the ground truth measurements acquired by x-ray diffraction (XRD) imaging. Results: Our scatter imaging system was able to define the location and composition of the various materials and tissues within the phantom. Cancerous breast tissue was detected and classified through automated spectral matching and an 86% correlation threshold. The total scan time for the sample was approximately 10 minutes and approaches workflow times for clinical use in intra-operative or other diagnostic tasks. Conclusion: This work demonstrates the first results from an anthropomorphic tissue equivalent scatter phantom to characterize a coherent scatter imaging system. The functionality of the system shows promise in applications such as intra-operative margin detection or virtual biopsy in the diagnosis of breast cancer. Future work includes using additional patient-derived tissues (e.g., human fat), and modeling additional organs

  19. SU-F-J-174: A Series of Computational Human Phantoms in DICOM-RT Format for Normal Tissue Dose Reconstruction in Epidemiological Studies

    Energy Technology Data Exchange (ETDEWEB)

    Pyakuryal, A; Moroz, B [National Cancer Institute, National Institutes of Health, Rockville, MD (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Pelletier, C; Jung, J [East Carolina University Greenville, NC (United States); Lee, C [National Cancer Institute, Rockville, MD (United States)

    2016-06-15

    Purpose: Epidemiological studies of second cancer risk in radiotherapy patients often require individualized dose estimates of normal tissues. Prior to 3D conformal radiation therapy planning, patient anatomy information was mostly limited to 2D radiological images or not even available. Generic patient CT images are often used in commercial radiotherapy treatment planning system (TPS) to reconstruct normal tissue doses. The objective of the current work was to develop a series of reference size computational human phantoms in DICOM-RT format for direct use in dose reconstruction in TPS. Methods: Contours of 93 organs and tissues were extracted from a series of pediatric and adult hybrid computational human phantoms (newborn, 1-, 5-, 10-, 15-year-old, and adult males and females) using Rhinoceros software. A MATLAB script was created to convert the contours into the DICOM-RT structure format. The simulated CT images with the resolution of 1×1×3 mm3 were also generated from the binary phantom format and coupled with the DICOM-structure files. Accurate volumes of the organs were drawn in the format using precise delineation of the contours in converted format. Due to complex geometry of organs, higher resolution (1×1×1 mm3) was found to be more efficient in the conversion of newborn and 1-year-old phantoms. Results: Contour sets were efficiently converted into DICOM-RT structures in relatively short time (about 30 minutes for each phantom). A good agreement was observed in the volumes between the original phantoms and the converted contours for large organs (NRMSD<1.0%) and small organs (NRMSD<7.7%). Conclusion: A comprehensive series of computational human phantoms in DICOM-RT format was created to support epidemiological studies of second cancer risks in radiotherapy patients. We confirmed the DICOM-RT phantoms were successfully imported into the TPS programs of major vendors.

  20. Monte Carlo study of the influence of energy spectra, mesh size, high Z element on dose and PVDR based on 1-D and 3-D heterogeneous mouse head phantom for Microbeam Radiation Therapy.

    Science.gov (United States)

    Lin, Hui; Jing, Jia; Xu, Liangfeng; Mao, Xiaoli

    2017-12-01

    To evaluate the influence of energy spectra, mesh sizes, high Z element on dose and PVDR in Microbeam Radiation Therapy (MRT) based on 1-D analogy-mouse-head-model (1-D MHM) and 3-D voxel-mouse-head-phantom (3-D VMHP) by Monte Carlo simulation. A Microbeam-Array-Source-Model was implemented into EGSnrc/DOSXYZnrc. The microbeam size is assumed to be 25μm, 50μm or 75μm in thickness and fixed 1mm in height with 200μmc-t-c. The influence of the energy spectra of ID17@ESRF and BMIT@CLS were investigated. The mesh size was optimized. PVDR in 1-D MHM and 3-D VMHP was compared with the homogeneous water phantom. The arc influence of 3-D VMHP filled with water (3-D VMHWP) was compared with the rectangle phantom. PVDR of the lower BMIT@CLS spectrum is 2.4times that of ID17@ESRF for lower valley dose. The optimized mesh is 5µm for 25µm, and 10µm for 50µm and 75µm microbeams with 200µmc-t-c. A 500μm skull layer could make PVDR difference up to 62.5% for 1-D MHM. However this influence is limited (influence is limited for the more depth (influence of 3-D heterogeneous media. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  1. EVALUATION OF EMF EXPOSURE OF MOBILE PHONES ON HUMAN HEAD

    Directory of Open Access Journals (Sweden)

    N. I. Vtornikova

    2017-01-01

    Full Text Available Introduction. Mobile phones are worldwide spread nowadays. Smartphones penetration is growing year after year. Numerous studies indicate the negative effect of EMF exposure of these devices on humans. Therefore, it is important to study the peculiarities of their influence on the target organ-the brain. It is important for solving this problem to find out the real situation of the distribution of energy flux density (EFD of EMF exposure near the front panel of the apparatus.The aim of the study is to determine and compare EMF exposure from smartphones and classic mobile phones on human head.Material and methods. The original method patented in the Russian Federation was used in this study. The used original measuring setup is also patented, developed and assembled by the authors of the study. The object of the study was classical mobile phones and smartphones widespread at the time of work.Results. We got the graphic of matrices of distribution of energy flux density (EFD of EMF exposure in the plane against the front panel of 10 apparatus corresponding to the topography of a human head. The study revealed peculiarities of this distribution in smartphones and the classic mobile phones and got the values of energy flux density (EFD of EMF exposure in the investigated devices acting primarily on the brain.Conclusions. The design of smartphones and mobile phones determines the overall picture of distribution of EFD of EMF exposure in the plane against the front panel for devices of a particular type. This picture must be taken into account when planning epidemiological and experimental studies to obtain comparable results. Progress in the development of mobile communication technologies has led to an increase in the electromagnetic load on users of modern devices.

  2. A new anthropometric phantom of the human leg for calibrating in vivo measurements of stable lead in bone using x-ray fluorescence

    International Nuclear Information System (INIS)

    Spitz, Henry; Jenkins, Mark; Lodwick, Jeffrey

    1997-01-01

    Full text. A new anthropometric phantom of the human leg has been developed for calibrating in vivo measurements of stable lead in the bone using x-ray fluorescence. The phantom reproduces the shape and radiological characteristics of the midshaft of the human leg and includes tissue substitutes for cortical bone, bone marrow, and muscle which have been formulated using polyurethanes and calcium carbonate to provide the desired characteristics of density x-ray attenuation, and calcium content. The phantom includes a set of simulated tibia bones, each containing a precisely known concentration of stable lead, that can be easily inserted into the leg. Formerly, of a set of plexiglas cylinders filled with plaster of-paris, each containing a known lead content, was the consensus standard calibration phantom. Tissue substitute materials used in the new anthropometric calibration phantom are much more uniform in density and composition than the plaster-of-paris phantoms and its realistic appearance provides a practical means of evaluating the variability in measurements results due to the changes in subject-detector positioning. Use of the new anthropometric calibration phantom results in a energy spectrum that closely resembles the spectrum observed when measuring a human subject. The energy spectrum produced by the plaster-of-paris phantom lacks the substantial Compton Scattering component produced by the leg muscle mass which leads to unrealistic estimates of in vivo measurement sensitivity. The minimum detection limit (MDL) for in vivo measurement of stable lead in bone, using an efficiency derived from the new anthropometric phantom, ranges from 18,6 parts per million (ppm) to 26,3 ppm using the K β1,3 /Elastic ratio or the K 1 /Elastic ratio, respectively. These values are significantly greater than the MDL cited in the literature obtained using a efficiency derived the conventional cylindrical plaster-of-paris phantom. Likewise, the realistic shape of the new

  3. The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. Pt. 6

    International Nuclear Information System (INIS)

    Zankl, M.; Panzer, W.; Drexler, G.

    1991-11-01

    Computed tomography (CT) is a technique which offers a high diagnostic capability; however, the dose to the patient is high compared to conventional radiography. This report provides a catalogue of organ doses resulting from CT examinations. The organ doses were calculated for the type of CT scanners most commonly used in the FRG and for three different radiation qualities. For the dose calculations, the patients were represented by the adult mathematical phantoms Adam and Eva. The radiation transport in the body was simulated using a Monte Carlo method. The doses were calculated as conversion factors of mean organ doses per air kerma free in air on the axis of rotation. Mean organ dose conversion factors are given per organ and per single CT slice of 1 cm width. The mean dose to an organ resulting from a particular CT examination can be estimated by summing up the contribution to the organ dose from each relevant slice. In order to facilitate the selection of the appropriate slices, a table is given which relates the mathematical phantoms' coordinates to certain anatomical landmarks in the human body. (orig.)

  4. The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. Pt. 3

    International Nuclear Information System (INIS)

    Drexler, G.; Panzer, W.; Widenmann, L.; Williams, G.; Zankl, M.

    1984-03-01

    This report gives tables of conversion factors for the calculation of organ doses from technical parameters of typical radiographic techniques. These conversion factors were calculated using a male and a female mathematical human phantom and an efficient Monte Carlo programme that determines the mean organ doses from the energy deposited in each organ. Each diagnostic X-ray examination is studied using three X-ray spectra resulting from three different high tension values. The conversion factors per unit entrance air dose in free air are given for sixteen organs and for the entrance and exit surface skin doses. The tables are actually valid only for the given parameters such as phantom dimensions, source-to-skin distance, projection and X-ray quality. This, of course, gives rise to some uncertainty when dealing with the individual technique and patient. The uncertainty in organ dose of adult patients, however, should not be very large, if the calculation is based on a similar geometry, and before all, on the actually administered entrance air dose in the selected high tension range according to the patient parameters. (orig.)

  5. Kinematics of the human mandible for different head postures.

    Science.gov (United States)

    Visscher, C M; Huddleston Slater, J J; Lobbezoo, F; Naeije, M

    2000-04-01

    The influence of head posture on movement paths of the incisal point (IP) and of the mandibular condyles during free open-close movements was studied. Ten persons, without craniomandibular or cervical spine disorders, participated in the study. Open close mandibular movements were recorded with the head in five postures, viz., natural head posture, forward head posture, military posture, and lateroflexion to the right and to the left side, using the Oral Kinesiologic Analysis System (OKAS-3D). This study showed that in a military head posture, the opening movement path of the incisal point is shifted anteriorly relative to the path in a natural head posture. In a forward head posture, the movement path is shifted posteriorly whereas during lateroflexion, it deviates to the side the head has moved to. Moreover, the intra-articular distance in the temporomandibular joint during closing is smaller with the head in military posture and greater in forward head posture, as compared to the natural head posture. During lateroflexion, the intra-articular distance on the ipsilateral side is smaller. The influence of head posture upon the kinematics of the mandible is probably a manifestation of differences in mandibular loading in the different head postures.

  6. The influence of tube voltage and phantom size in computed tomography on the dose-response relationship of dicentrics in human blood samples

    International Nuclear Information System (INIS)

    Jost, G; Pietsch, H; Lengsfeld, P; Voth, M; Schmid, E

    2010-01-01

    The aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placed in tissue equivalent abdomen phantoms of standard, pediatric and adipose sizes were exposed at dose levels up to 0.1 Gy using a 64-slice CT scanner. It was found that both the tube voltage and the phantom size significantly influenced the CT scan-induced linear dose-response relationship of dicentrics in human lymphocytes. Using the same phantom (standard abdomen), 80 kV CT x-rays were biologically more effective than 140 kV CT x-rays. However, it could also be determined that the applied phantom size had much more influence on the biological effectiveness. Obviously, the increasing slopes of the CT scan-induced dose response relationships of dicentrics in human lymphocytes obtained in a pediatric, a standard and an adipose abdomen have been induced by scattering effects of photons, which strongly increase with increasing phantom size.

  7. The influence of tube voltage and phantom size in computed tomography on the dose-response relationship of dicentrics in human blood samples

    Energy Technology Data Exchange (ETDEWEB)

    Jost, G; Pietsch, H [TRG Diagnostic Imaging, Bayer Schering Pharma AG, Berlin (Germany); Lengsfeld, P; Voth, M [Global Medical Affairs Diagnostic Imaging, Bayer Schering Pharma AG, Berlin (Germany); Schmid, E, E-mail: Ernst.Schmid@lrz.uni-muenchen.d [Institute for Cell Biology, Center for Integrated Protein Science, University of Munich (Germany)

    2010-06-07

    The aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placed in tissue equivalent abdomen phantoms of standard, pediatric and adipose sizes were exposed at dose levels up to 0.1 Gy using a 64-slice CT scanner. It was found that both the tube voltage and the phantom size significantly influenced the CT scan-induced linear dose-response relationship of dicentrics in human lymphocytes. Using the same phantom (standard abdomen), 80 kV CT x-rays were biologically more effective than 140 kV CT x-rays. However, it could also be determined that the applied phantom size had much more influence on the biological effectiveness. Obviously, the increasing slopes of the CT scan-induced dose response relationships of dicentrics in human lymphocytes obtained in a pediatric, a standard and an adipose abdomen have been induced by scattering effects of photons, which strongly increase with increasing phantom size.

  8. Calculation of organ doses from environmental gamma rays using human phantoms and Monte Carlo methods. Pt. 1

    International Nuclear Information System (INIS)

    Saito, K.; Petoussi, N.; Zankl, M.; Veit, R.; Jacob, P.; Drexler, G.

    1990-01-01

    Organ doses from environmental γ-rays (U-238, Th-232, K-40) were calculated using Monte Carlo methods for three typical sources of a semi-infinite volume source in the air, an infinite plane source in the ground and a volume source in the ground. γ-ray fields in the natural environment were simulated rigourously without approximations or simplifications in the intermediate steps except for the disturbance of the radiation field by the human body which was neglected. Organ doses were calculated for four anthropomorphic phantoms representing a baby, a child, a female and a male adult. The dose of a fetus is given by the dose to the uterus of the adult female. Air kerma and dose conversion factors normalised to air kerma and to source intensity are given for monoenergetic sources and for the natural radionuclides. (orig./HP)

  9. Design of a phantom equivalent to measure bone-fluorine in a human's hand via delayed neutron activation analysis

    International Nuclear Information System (INIS)

    Mostafaei, F; McNeill, F E; Chettle, D R; Prestwich, W V; Inskip, M

    2013-01-01

    Fluorine is an element that can be either beneficial or harmful, depending on the total amount accumulated in the teeth or bones. In our laboratory, we have developed a non-invasive technique for the in vivo measurement of fluoride in bone using neutron activation analysis and performed the first pilot human study. Fluoride in humans is quantified by comparing the γ-ray signal from a person to the γ-ray signal obtained from appropriate anthropomorphic calibration phantoms. An identified problem with existing fluoride phantoms is contamination with aluminum. Aluminum creates an interfering γ-ray signal which, although it can be subtracted out, increases the uncertainty in the measurement and worsens the detection limit. This paper outlines a series of studies undertaken to develop a better calibration phantom for fluorine measurement, which does not have aluminum contamination. (paper)

  10. Comparison between the calculated and measured dose distributions for four beams of 6 MeV linac in a human-equivalent phantom

    Directory of Open Access Journals (Sweden)

    Reda Sonia M.

    2006-01-01

    Full Text Available Radiation dose distributions in various parts of the body are of importance in radiotherapy. Also, the percent depth dose at different body depths is an important parameter in radiation therapy applications. Monte Carlo simulation techniques are the most accurate methods for such purposes. Monte Carlo computer calculations of photon spectra and the dose ratios at surfaces and in some internal organs of a human equivalent phantom were performed. In the present paper, dose distributions in different organs during bladder radiotherapy by 6 MeV X-rays were measured using thermoluminescence dosimetry placed at different points in the human-phantom. The phantom was irradiated in exactly the same manner as in actual bladder radiotherapy. Four treatment fields were considered to maximize the dose at the center of the target and minimize it at non-target healthy organs. All experimental setup information was fed to the MCNP-4b code to calculate dose distributions at selected points inside the proposed phantom. Percent depth dose distribution was performed. Also, the absorbed dose as ratios relative to the original beam in the surrounding organs was calculated by MCNP-4b and measured by thermoluminescence dosimetry. Both measured and calculated data were compared. Results indicate good agreement between calculated and measured data inside the phantom. Comparison between MCNP-4b calculations and measurements of depth dose distribution indicated good agreement between both.

  11. Whole-body detector calibrating with a modular phantom

    International Nuclear Information System (INIS)

    Minev, L.; Boshkova, T.; Uzunov, P.

    1995-01-01

    Human body models (phantoms) of various size and weight are produced in order to calibrate gamma spectrometers for accurate activity measurement. The phantoms are built of separate modules with mass of 0.5 kg and size 20 x 14 x 2 cm. There are modules with standard Eu-152 and Am-241 radioactivity designed for homogenous radioactivity imitating and critical organs moulding, as well as 'zero' -phantom modules without activity imitating a standard human body. Human organs are modelled by 11 x 9 x 0.5 cm modules with 0.16 kg mass. The phantoms have been used to obtain calibration curves and absolute efficiencies for selected energies of radionuclides expected to be found in the Kozloduy NPP staff. It is shown that the efficiency depends not only on the mass but on the geometric size of the measured object. Scanning of phantoms has been carried out and a profile of activity obtained. The profile consists of an abrupt rising of the sum of pulses (measuring time - 20 s) when the detector passes from neck to chest, a plateau when it moves over the head or the trunk and gradual decrease over the legs. Profiles of activity in organs are best obtained with a lead collimator. 4 refs., 7 figs., 2 tabs

  12. Whole-body detector calibrating with a modular phantom

    Energy Technology Data Exchange (ETDEWEB)

    Minev, L; Boshkova, T; Uzunov, P [Sofia Univ. (Bulgaria). Fizicheski Fakultet

    1996-12-31

    Human body models (phantoms) of various size and weight are produced in order to calibrate gamma spectrometers for accurate activity measurement. The phantoms are built of separate modules with mass of 0.5 kg and size 20 x 14 x 2 cm. There are modules with standard Eu-152 and Am-241 radioactivity designed for homogenous radioactivity imitating and critical organs moulding, as well as `zero` -phantom modules without activity imitating a standard human body. Human organs are modelled by 11 x 9 x 0.5 cm modules with 0.16 kg mass. The phantoms have been used to obtain calibration curves and absolute efficiencies for selected energies of radionuclides expected to be found in the Kozloduy NPP staff. It is shown that the efficiency depends not only on the mass but on the geometric size of the measured object. Scanning of phantoms has been carried out and a profile of activity obtained. The profile consists of an abrupt rising of the sum of pulses (measuring time - 20 s) when the detector passes from neck to chest, a plateau when it moves over the head or the trunk and gradual decrease over the legs. Profiles of activity in organs are best obtained with a lead collimator. 4 refs., 7 figs., 2 tabs.

  13. Human Papillomavirus Genome Integration and Head and Neck Cancer.

    Science.gov (United States)

    Pinatti, L M; Walline, H M; Carey, T E

    2018-06-01

    We conducted a critical review of human papillomavirus (HPV) integration into the host genome in oral/oropharyngeal cancer, reviewed the literature for HPV-induced cancers, and obtained current data for HPV-related oral and oropharyngeal cancers. In addition, we performed studies to identify HPV integration sites and the relationship of integration to viral-host fusion transcripts and whether integration is required for HPV-associated oncogenesis. Viral integration of HPV into the host genome is not required for the viral life cycle and might not be necessary for cellular transformation, yet HPV integration is frequently reported in cervical and head and neck cancer specimens. Studies of large numbers of early cervical lesions revealed frequent viral integration into gene-poor regions of the host genome with comparatively rare integration into cellular genes, suggesting that integration is a stochastic event and that site of integration may be largely a function of chance. However, more recent studies of head and neck squamous cell carcinomas (HNSCCs) suggest that integration may represent an additional oncogenic mechanism through direct effects on cancer-related gene expression and generation of hybrid viral-host fusion transcripts. In HNSCC cell lines as well as primary tumors, integration into cancer-related genes leading to gene disruption has been reported. The studies have shown that integration-induced altered gene expression may be associated with tumor recurrence. Evidence from several studies indicates that viral integration into genic regions is accompanied by local amplification, increased expression in some cases, interruption of gene expression, and likely additional oncogenic effects. Similarly, reported examples of viral integration near microRNAs suggest that altered expression of these regulatory molecules may also contribute to oncogenesis. Future work is indicated to identify the mechanisms of these events on cancer cell behavior.

  14. Why infest the loved ones--inherent human behaviour indicates former mutualism with head lice.

    Science.gov (United States)

    Rózsa, Lajos; Apari, Péter

    2012-05-01

    Head lice transmit to new hosts when people lean their heads together. Humans frequently touch their heads to express friendship or love, while this behaviour is absent in apes. We hypothesize that this behaviour was adaptive because it enabled people to acquire head lice infestations as early as possible to provoke an immune response effective against both head lice and body lice throughout the subsequent periods of their life. This cross-immunity could provide some defence against the body-louse-borne lethal diseases like epidemic typhus, trench fever, relapsing fever and the classical plague. Thus the human 'touching heads' behaviour probably acts as an inherent and unconscious 'vaccination' against body lice to reduce the threat exposed by the pathogens they may transmit. Recently, the eradication of body-louse-borne diseases rendered the transmission of head lice a maladaptive, though still widespread, behaviour in developed societies.

  15. Phantom Pain

    Science.gov (United States)

    ... Because this is yet another version of tangled sensory wires, the result can be pain. A number of other factors are believed to contribute to phantom pain, including damaged nerve endings, scar tissue at the site of the amputation and the physical memory of pre-amputation pain in the affected area. ...

  16. Human Papilloma Virus in Head and Neck Squamous Cell Cancer

    Science.gov (United States)

    Asvadi Kermani, I; Seifi, SH; Dolatkhah, R; Sakhinia, E; Dastgiri, S; Ebrahimi, A; Lotfy, A; Esmaeili, HA; G, Mohammadi; M, Naderpour; SH, Hajalipour; Haggi A, Asghari; M, Nadri

    2012-01-01

    Background Epidemiologic and molecular evidences have established a strong link between high risk types of Human Papilloma Virus and a subgroup of Head and Neck Squamous Cell Carcinomas (HNSCC). We evaluated the frequency of HPV positivity in HNSCC and its relationship to demographic and some risk factor variables in an open case- control study. Methods Fourteen recently diagnosed patients with squamous cell cancer of oropharynx, hypopharynx and larynx aged 18-50 years were examined from 2008-2010 in Tabriz, Iran. HPV DNA was extracted from paraffin-embedded blocks of each patient's sample for PCR evaluation. Saliva samples of 94 control cancer-free subjects were collected for DNA analysis. Multivariable logistic regression method was used to calculate odds ratio for case-control comparisons. Results High risk HPV was detected in 6(42.8%) patients, and 6(5.3%) control subjects which was statistically significant (p<0.0001). HPV-18 was the most frequent type both in the cases and controls. HPV-16 DNA was detected in two patients of the case group, but it was not detected in any of the controls. The relation between demographic and risk factor variables was not statistically significant. Conclusion HPV infection has a significant impact on HNSCC. Despite HPV-16 stronger impact, HPV-18 is more likely to cause malignant degeneration in such cancers amongst some communities. It is vital to introduce and conduct immunization schedules in health care systems to protect communities to some extent. PMID:25780535

  17. MO-F-CAMPUS-T-01: IROC Houston QA Center’s Anthropomorphic Proton Phantom Program

    International Nuclear Information System (INIS)

    Lujano, C; Hernandez, N; Keith, T; Nguyen, T; Taylor, P; Molineu, A; Followill, D

    2015-01-01

    Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to be approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647

  18. MO-F-CAMPUS-T-01: IROC Houston QA Center’s Anthropomorphic Proton Phantom Program

    Energy Technology Data Exchange (ETDEWEB)

    Lujano, C; Hernandez, N; Keith, T; Nguyen, T; Taylor, P; Molineu, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to be approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647.

  19. Influence of the phantom shape (slab, cylinder or Alderson) on the performance of an Hp(3) eye dosemeter

    International Nuclear Information System (INIS)

    Behrens, R.; Hupe, O.

    2016-01-01

    In the past, the operational quantity H p (3) was defined for calibration purposes in a slab phantom. Recently, an additional phantom in the form of a cylinder has been suggested for eye lens dosimetry, as a cylinder much better approximates the shape of a human head. Therefore, this work investigates which of the two phantoms, slab or cylinder, is more suitable for calibrations and type tests of eye dosemeters. For that purpose, a typical H p (3) eye dosemeter was irradiated on a slab, a cylinder and on a human-like Alderson phantom. It turned out that the response on the three phantoms is nearly equal for angles of radiation incidence up to 45 deg. and deviates only at larger angles of incidence. Thus, calibrations (usually performed at 0 deg. radiation incidence) are practically equivalent on both the slab and the cylinder phantoms. However, type tests (up to 75 deg. or even 90 deg. radiation incidence) should be carried out on a cylinder phantom, as also for large angles of incidence the response on the cylinder and the Alderson phantoms is rather similar, whereas the response on the slab significantly deviates from the one on the Alderson phantom. (authors)

  20. SU-E-J-119: Head-And-Neck Digital Phantoms for Geometric and Dosimetric Uncertainty Evaluation of CT-CBCT Deformable Image Registration

    International Nuclear Information System (INIS)

    Shen, Z; Koyfman, S; Xia, P; Bzdusek, K

    2015-01-01

    Purpose: To evaluate geometric and dosimetric uncertainties of CT-CBCT deformable image registration (DIR) algorithms using digital phantoms generated from real patients. Methods: We selected ten H&N cancer patients with adaptive IMRT. For each patient, a planning CT (CT1), a replanning CT (CT2), and a pretreatment CBCT (CBCT1) were used as the basis for digital phantom creation. Manually adjusted meshes were created for selected ROIs (e.g. PTVs, brainstem, spinal cord, mandible, and parotids) on CT1 and CT2. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was applied to CBCT1 to create a simulated mid-treatment CBCT (CBCT2). The CT-CBCT digital phantom consisted of CT1 and CBCT2, which were linked by the reference DVF. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten digital phantoms. The images, ROIs, and volumetric doses were mapped from CT1 to CBCT2 using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.83 to 0.94 for Demons, from 0.82 to 0.95 for B-Spline, and from 0.67 to 0.89 for intensity-based DIR. The average Hausdorff distances for selected ROIs were from 2.4 to 6.2 mm for Demons, from 1.8 to 5.9 mm for B-Spline, and from 2.8 to 11.2 mm for intensity-based DIR. The average absolute dose errors for selected ROIs were from 0.7 to 2.1 Gy for Demons, from 0.7 to 2.9 Gy for B- Spline, and from 1.3 to 4.5 Gy for intensity-based DIR. Conclusion: Using clinically realistic CT-CBCT digital phantoms, Demons and B-Spline were shown to have similar geometric and dosimetric uncertainties while intensity-based DIR had the worst uncertainties. CT-CBCT DIR has the potential to provide accurate CBCT-based dose verification for H&N adaptive radiotherapy. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; S Koyfman: None; P Xia

  1. Human Papilloma Virus (HPV) Induced Head & Neck Squamous Cell Carcinoma: A Comprehensive Retrospect

    Science.gov (United States)

    Nishat, Roquaiya; Ramachandra, Sujatha; Kumar, Harish; Bandyopadhyay, Alokenath

    2015-01-01

    Head and Neck Squamous Cell Carcinoma accounts for the sixth most common malignancy occurring worldwide with tobacco and alcohol being the two well established risk factors. In the recent years, substantial evidence has been obtained that Human Papilloma Virus (HPV) associated head and neck cancers are on the rise. This article provides an insight into the structure of HPV genome, molecular pathogenesis, detection methods and clinical implications of HPV positive Head and Neck Squamous Cell Carcinoma. PMID:26266234

  2. NMR-CT image and symbol phantoms

    International Nuclear Information System (INIS)

    Hongo, Syozo; Yamaguchi, Hiroshi; Takeshita, Hiroshi

    1990-01-01

    We have developed Japanese phantoms in two procedures. One is described as a mathematical expression. Another is 'symbol phantoms' in 3 dimensional picture-elements, each of which symbolize an organ name. The concept and the algorithm of the symbol phantom enables us to make a phantom for a individual in terms of all his transversal section images. We got 85 transversal section images of head and trunk parts, and those of 40 legs parts by using NMR-CT. We have made the individual phantom for computation of organ doses. The transversal section images were not so clear to identify all organs needed to dose estimation that we had to do hand-editing the shapes of organs with viewing a typical section images: we could not yet make symbol phantom in a automatic editing. Symbols were coded to be visual cords as ASCII characters. After we got the symbol phantom of the first stage, we can edit it easily using a word-processor. Symbol phantom could describe more freely the shape of organs than mathematical phantom. Symbol phantom has several advantages to be an individual phantom, but the only difficult point is how to determine its end-point as a reference man when we apply the method to build the reference man. (author)

  3. Computational voxel phantom, associated to anthropometric and anthropomorphic real phantom for dosimetry in human male pelvis radiotherapy; Fantoma computacional de voxel, associado a fantoma real antropomorfico antropometrico, para dosimetria em radioterapia de pelve masculina

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cleuza Helena Teixeira; Campos, Tarcisio Passos Ribeiro de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares]. E-mail: campos@nuclear.ufmg.br

    2005-07-01

    This paper addresses a computational model of voxels through MCNP5 Code and the experimental development of an anthropometric and anthropomorphic phantom for dosimetry in human male pelvis brachytherapy focusing prostatic tumors. For elaboration of the computational model of the human male pelvis, anatomical section images from the Visible Man Project were applied. Such selected and digital images were associated to a numeric representation, one for each section. Such computational representation of the anatomical sections was transformed into a bi-dimensional mesh of equivalent tissue. The group of bidimensional meshes was concatenated forming the three-dimensional model of voxels to be used by the MCNP5 code. In association to the anatomical information, data from the density and chemical composition of the basic elements, representatives of the organs and involved tissues, were setup in a material database for the MCNP-5. The model will be applied for dosimetric evaluations in situations of irradiation of the human masculine pelvis. Such 3D model of voxel is associated to the code of transport of particles MCNP5, allowing future simulations. It was also developed the construction of human masculine pelvis phantom, based on anthropometric and anthropomorphic dates and in the use of representative equivalent tissues of the skin, fatty, muscular and glandular tissue, as well as the bony structure.This part of work was developed in stages, being built the bony cast first, later the muscular structures and internal organs. They were then jointly mounted and inserted in the skin cast. The representative component of the fatty tissue was incorporate and accomplished the final retouchings in the skin. The final result represents the development of two important essential tools for elaboration of computational and experimental dosimetry. Thus, it is possible its use in calibrations of pre-existent protocols in radiotherapy, as well as for tests of new protocols, besides

  4. Head Pose Estimation Using Multilinear Subspace Analysis for Robot Human Awareness

    Science.gov (United States)

    Ivanov, Tonislav; Matthies, Larry; Vasilescu, M. Alex O.

    2009-01-01

    Mobile robots, operating in unconstrained indoor and outdoor environments, would benefit in many ways from perception of the human awareness around them. Knowledge of people's head pose and gaze directions would enable the robot to deduce which people are aware of the its presence, and to predict future motions of the people for better path planning. To make such inferences, requires estimating head pose on facial images that are combination of multiple varying factors, such as identity, appearance, head pose, and illumination. By applying multilinear algebra, the algebra of higher-order tensors, we can separate these factors and estimate head pose regardless of subject's identity or image conditions. Furthermore, we can automatically handle uncertainty in the size of the face and its location. We demonstrate a pipeline of on-the-move detection of pedestrians with a robot stereo vision system, segmentation of the head, and head pose estimation in cluttered urban street scenes.

  5. Oncogenic impact of human papilloma virus in head and neck cancer.

    LENUS (Irish Health Repository)

    Heffernan, C B

    2012-02-01

    There is considerable debate within the literature about the significance of human papilloma virus in head and neck squamous cell carcinoma, and its potential influence on the prevention, diagnosis, grading, treatment and prognosis of these cancers. Cigarette smoking and alcohol consumption have traditionally been cited as the main risk factors for head and neck cancers. However, human papilloma virus, normally associated with cervical and other genital carcinomas, has emerged as a possible key aetiological factor in head and neck squamous cell carcinoma, especially oropharyngeal cancers. These cancers pose a significant financial burden on health resources and are increasing in incidence. The recent introduction of vaccines targeted against human papilloma virus types 16 and 18, to prevent cervical cancer, has highlighted the need for ongoing research into the importance of human papilloma virus in head and neck squamous cell carcinoma.

  6. Spectra from 2.5-15 μm of tissue phantom materials, optical clearing agents and ex vivo human skin: implications for depth profiling of human skin

    International Nuclear Information System (INIS)

    Viator, John A; Choi, Bernard; Peavy, George M; Kimel, Sol; Nelson, J Stuart

    2003-01-01

    Infrared measurements have been used to profile or image biological tissue, including human skin. Usually, analysis of such measurements has assumed that infrared absorption is due to water and collagen. Such an assumption may be reasonable for soft tissue, but introduction of exogenous agents into skin or the measurement of tissue phantoms has raised the question of their infrared absorption spectrum. We used Fourier transform infrared spectroscopy in attenuated total reflection mode to measure the infrared absorption spectra, in the range of 2-15 μm, of water, polyacrylamide, Intralipid, collagen gels, four hyperosmotic clearing agents (glycerol, 1,3-butylene glycol, trimethylolpropane, Topicare TM ), and ex vivo human stratum corneum and dermis. The absorption spectra of the phantom materials were similar to that of water, although additional structure was noted in the range of 6-10 μm. The absorption spectra of the clearing agents were more complex, with molecular absorption bands dominating between 6 and 12 μm. Dermis was similar to water, with collagen structure evident in the 6-10 μm range. Stratum corneum had a significantly lower absorption than dermis due to a lower content of water. These results suggest that the assumption of water-dominated absorption in the 2.5-6 μm range is valid. At longer wavelengths, clearing agent absorption spectra differ significantly from the water spectrum. This spectral information can be used in pulsed photothermal radiometry or utilized in the interpretation of reconstructions in which a constant μ ir is used. In such cases, overestimating μ ir will underestimate chromophore depth and vice versa, although the effect is dependent on actual chromophore depth. (note)

  7. Evaluation of sub-zero and residence times after continuous versus multiple intermittent cryogen spray cooling exposure on human skin phantom

    OpenAIRE

    Ramirez-San-Juan, JC; Tuqan, AT; Kelly, KM; Nelson, JS; Aguilar, G

    2004-01-01

    Cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during various laser dermatologic surgeries. However, as the application of single or multiple cryogen spurts becomes available on some commercial lasers devices, it is necessary to determine the optimal CSC parameters for different laser surgeries. The objective of this study was to measure the time the sprayed surface of a human skin phantom (HSP) remains below water freezing temperature 0°C, referred to as subzero...

  8. THREE DIMENSIONAL DIGITIZATION OF HUMAN HEAD BY FUSING STRUCTURED LIGHT AND CONTOURS

    Institute of Scientific and Technical Information of China (English)

    Jin Gang; Li Dehua; Hu Hanping; Hu Bing

    2002-01-01

    Three dimensional digitization of human head is desired in many applications. In this paper, an information fusion based scheme is presented to obtain 3-D information of human head. Structured light technology is employed to measure depth. For the special reflection areas,in which the structured light stripe can not be detected directly, the shape of the structured light stripe can be calculated from the corresponding contour. By fusing the information of structured light and the contours, the problem of reflectance influence is solved, and the whole shape of head,including hair area, can be obtained. Some good results are obtained.

  9. Polymorphisms in human DNA repair genes and head and neck ...

    Indian Academy of Sciences (India)

    Abstract. Genetic polymorphisms in some DNA repair proteins are associated with a number of malignant transformations like head and ... Such studies may benefit from analysis of multiple genes or polymorphisms and from the ... low survival and high morbidity when diagnosed in advanced ...... racial and/or ethnic cohort.

  10. Utilization of MAX and FAX human phantoms for space radiation exposure calculations using HZETRN

    Science.gov (United States)

    Qualls, Garry; Slaba, Tony; Clowdsley, Martha; Blattnig, Steve; Walker, Steven; Simonsen, Lisa

    To estimate astronaut health risk due to space radiation, one must have the ability to calculate, for known radiation environments external to the body, particle spectra, LET spectra, dose, dose equivalent, or gray equivalent that are averaged over specific organs or tissue types. This may be accomplished using radiation transport software and computational human body tissue models. Historically, NASA scientists have used the HZETRN software to calculate radiation transport through both vehicle shielding materials and body tissue. The Computerized Anatomical Man (CAM) and the Computerized Anatomical Female (CAF) body models, combined with the CAMERA software, have been used for body tissue self-shielding calculations. The CAM and CAF, which were developed in 1973 and 1992, respectively, model the 50th percentile U.S. Air Force male and female and are constructed using individual quadric surfaces that combine to form thousands of solid regions that represent specific tissues and structures within the body. In order to transport an external radiation environment to a point within one of the body models using HZETRN, a directional distribution of the tissues surrounding that point is needed. The CAMERA software is used to "ray trace" the CAM and CAF models, providing the thickness of each tissue type traversed along each of a large number of rays originating at a dose point. More recently, R. Kramer of the Departmento de Energia Nuclear, Universidade Federal de Pernambuco in Brazil and his co-workers developed the Male Adult voXel (MAX) model and the Female Adult voXel (FAX). These voxel-based body models were developed using segmented Computed Tomography (CT) scans of adult cadavers, and the quantities and distributions of various body tissues have been adjusted to match those specified in the International Commission on Radiological Protection (ICRP) reference adult male and female. A new set of tools has been developed to facilitate space radiation exposure

  11. Human papilloma virus: a new risk factor in a subset of head and neck cancers.

    Science.gov (United States)

    Bisht, Manisha; Bist, Sampan Singh

    2011-01-01

    Head and neck cancer is the sixth most common malignancy worldwide. Tobacco smoking and alcohol consumption are two well known behavioral risk factors associated with head and neck cancer. Recently, evidence is mounting that infection with human papilloma virus, most commonly human papilloma virus-16 is responsible for a subset of head and neck squamous cell carcinoma especially tumors of tonsillar origin. The molecular pathway used by human papilloma virus to trigger malignant transformation of tissue is different from that of other well known risk factors, i.e. smoking and alcohol, associated with squamous cell carcinoma. Apparently, these subsets of patients with human papilloma virus positive tumor are more likely to have a better prognosis than human papilloma virus negative tumor. Considering this fact, the human papilloma virus infection should be determined in all oropharyngeal cancers since it can have a major impact on the decision making process of the treatment.

  12. 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 (original ICRP reference phantoms, it is believed that the polygon-surface version of ICRP reference phantoms properly developed will not only provide the same or similar dose values (say, difference <5 or 10%) for highly penetrating radiations, but also provide correct dose values for the weakly penetrating

  13. Targeting ADAM12 in human disease: head, body or tail?

    DEFF Research Database (Denmark)

    Jacobsen, J; Wewer, U M

    2009-01-01

    ) and insulin-like growth factor receptor signaling. The body of the protein (consisting of the disintegrin, cysteine-rich, and EGF-like domains) is involved in contacts with the extracellular matrix and other cells through interactions with integrins and syndecans. Finally, the tail of the protein (consisting......ADAM12/meltrin alpha is a type I transmembrane multidomain protein involved in tumor progression and other severe diseases, including osteoarthritis, and as such could be considered as a potential drug target. In addition to protease activity, ADAM12 possesses cell binding and cell signaling...... properties. This functional trinity is reflected in the structure of ADAM12, which can be divided into head, body, and tail. The head of the protein (consisting of the pro and catalytic domains) mediates processing of growth factors and cytokines and has been implicated in epidermal growth factor (EGF...

  14. 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

    2004-12-07

    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.

  15. Growth trajectories of the human embryonic head and periconceptional maternal conditions.

    Science.gov (United States)

    Koning, I V; Baken, L; Groenenberg, I A L; Husen, S C; Dudink, J; Willemsen, S P; Gijtenbeek, M; Koning, A H J; Reiss, I K M; Steegers, E A P; Steegers-Theunissen, R P M

    2016-05-01

    Can growth trajectories of the human embryonic head be created using 3D ultrasound (3D-US) and virtual reality (VR) technology, and be associated with second trimester fetal head size and periconceptional maternal conditions? Serial first trimester head circumference (HC) and head volume (HV) measurements were used to create reliable growth trajectories of the embryonic head, which were significantly associated with fetal head size and periconceptional maternal smoking, age and ITALIC! in vitro fertilization (IVF)/intra-cytoplasmic sperm injection (ICSI) treatment. Fetal growth is influenced by periconceptional maternal conditions. We selected 149 singleton pregnancies with a live born non-malformed fetus from the Rotterdam periconception cohort. Bi-parietal diameter and occipital frontal diameter to calculate HC, HV and crown-rump length (CRL) were measured weekly between 9 + 0 and 12 + 6 weeks gestational age (GA) using 3D-US and VR. Fetal HC was obtained from second trimester structural anomaly scans. Growth trajectories of the embryonic head were created with general additive models and linear mixed models were used to estimate associations with maternal periconceptional conditions as a function of GA and CRL, respectively. A total of 303 3D-US images of 149 pregnancies were eligible for embryonic head measurements (intra-class correlation coefficients >0.99). Associations were found between embryonic HC and fetal HC ( ITALIC! ρ = 0.617, ITALIC! P head measured by HC and HV (All ITALIC! P head may be of benefit in future early antenatal care. This study was funded by the Department of Obstetrics and Gynaecology, Erasmus MC University Medical Centre and Sophia Foundation for Medical Research, Rotterdam, The Netherlands (SSWO grant number 644). No competing interests are declared. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email

  16. The role of human papillomavirus in head and neck cancer

    DEFF Research Database (Denmark)

    Lajer, Christel Braemer; Buchwald, Christian von

    2010-01-01

    Over the last 20 years, there has been increasing awareness of a subset of squamous cell carcinomas of the head and neck (HNSCC), i.e. HPV-positive HNSCC. These cancers seem to differ somewhat from HPV-negative HNSCC. Patients with HPV-positive HNSCC tend to be younger and have a lower intake of ......-negative HNSCC, and this seems to be related to the immune system. Whether the new vaccines for HPV will protect not only against cervical cancer but also against HPV-positive HNSCC remains unknown....

  17. Eyewear Computing – Augmenting the Human with Head-mounted Wearable Assistants (Dagstuhl Seminar 16042)

    OpenAIRE

    Bulling, Andreas; Cakmakci, Ozan; Kunze, Kai; Rehg, James M.

    2016-01-01

    The seminar was composed of workshops and tutorials on head-mounted eye tracking, egocentric vision, optics, and head-mounted displays. The seminar welcomed 30 academic and industry researchers from Europe, the US, and Asia with a diverse background, including wearable and ubiquitous computing, computer vision, developmental psychology, optics, and human-computer interaction. In contrast to several previous Dagstuhl seminars, we used an ignite talk format to reduce the time of talks to...

  18. Human Papilloma Virus Associated Squamous Cell Carcinoma of the Head and Neck

    OpenAIRE

    Ajila, Vidya; Shetty, Harish; Babu, Subhas; Shetty, Veena; Hegde, Shruthi

    2015-01-01

    Oral cancer is one of the commonest causes for mortality and morbidity with squamous cell carcinoma being the sixth most frequent malignant tumour worldwide. In addition to tobacco and alcohol, human papilloma virus (HPV) is associated with a proportion of head and neck cancers. As in cervical cancers, HPV types 16 and 18 are the cause of malignant transformation. HPV-positive cancers of head and neck have unique characteristics such as occurrence in a younger age group, distinct clinical and...

  19. Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations

    Energy Technology Data Exchange (ETDEWEB)

    Cassola, V F; Kramer, R; De Oliveira Lira, C A B; Khoury, H J [Department of Nuclear Energy, Federal University of Pernambuco, Avenida Professor Luiz Freire, 1000, CEP 50740-540, Recife, PE (Brazil); Milian, F M, E-mail: rkramer@uol.com.br [Department of Exact Science and Technology, State University of Santa Cruz, Campus Soane Nazare de Andrade, Km 16 Rodovia Ilheus-Itabuna, CEP 45662-000, Ilheus, BA (Brazil)

    2011-07-07

    Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also

  20. An effective dose assessment technique with NORM added consumer products using skin-point source on computational human phantom

    International Nuclear Information System (INIS)

    Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Hyun Cheol; Choi, Hyun Joon; Testa, Mauro; Lee, Jae Kook; Yeom, Yeon Soo; Kim, Chan Hyeong; Min, Chul Hee

    2016-01-01

    The aim of this study is to develop the assessment technique of the effective dose by calculating the organ equivalent dose with a Monte Carlo (MC) simulation and a computational human phantom for the naturally occurring radioactive material (NORM) added consumer products. In this study, we suggests the method determining the MC source term based on the skin-point source enabling the convenient and conservative modeling of the various type of the products. To validate the skin-point source method, the organ equivalent doses were compared with that by the product modeling source of the realistic shape for the pillow, waist supporter, sleeping mattress etc. Our results show that according to the source location, the organ equivalent doses were observed as the similar tendency for both source determining methods, however, it was observed that the annual effective dose with the skin-point source was conservative than that with the modeling source with the maximum 3.3 times higher dose. With the assumption of the gamma energy of 1 MeV and product activity of 1 Bq g"−"1, the annual effective doses of the pillow, waist supporter and sleeping mattress with skin-point source was 3.09E-16 Sv Bq"−"1 year"−"1, 1.45E-15 Sv Bq"−"1 year"−"1, and 2,82E-16 Sv Bq"−"1 year"−"1, respectively, while the product modeling source showed 9.22E-17 Sv Bq"−"1 year"−"1, 9.29E-16 Sv Bq"−"1 year"−"1, and 8.83E-17 Sv Bq"−"1 year"−"1, respectively. In conclusion, it was demonstrated in this study that the skin-point source method could be employed to efficiently evaluate the annual effective dose due to the usage of the NORM added consumer products. - Highlights: • We evaluate the exposure dose from the usage of NORM added consumer products. • We suggest the method determining the MC source term based on the skin-point source. • To validate the skin-point source, the organ equivalent doses were compared with that the modeling source. • The skin-point source could

  1. The role of human papillomavirus in head and neck cancer

    DEFF Research Database (Denmark)

    Lajer, Christel Braemer; Buchwald, Christian von

    2010-01-01

    Over the last 20 years, there has been increasing awareness of a subset of squamous cell carcinomas of the head and neck (HNSCC), i.e. HPV-positive HNSCC. These cancers seem to differ somewhat from HPV-negative HNSCC. Patients with HPV-positive HNSCC tend to be younger and have a lower intake...... of tobacco and alcohol. Distinct molecular profiles separate them from HPV-negative cancers and show similarities with HPV-positive cervical SCC. There is evidence that HPV-positive HNSCC is a sexually transmitted disease. Patients with HPV-positive HNSCC are often diagnosed at a late stage with large cystic......-negative HNSCC, and this seems to be related to the immune system. Whether the new vaccines for HPV will protect not only against cervical cancer but also against HPV-positive HNSCC remains unknown....

  2. Phantom position dependence

    International Nuclear Information System (INIS)

    Thorson, M.R.; Endres, G.W.R.

    1981-01-01

    Sensitivity of the Hanford dosimeter response to its position relative to the phantom and the neutron source has always been recognized. A thorough investigation was performed to quantify dosimeter response according to: (a) dosimeter position on phantom, (b) dosimeter distance from phantom, and (c) angular relationship of dosimeter relative to neutron source and phantom. Results were obtained for neutron irradiation at several different energies

  3. Development of a phantom for quality control of radiosurgery

    International Nuclear Information System (INIS)

    Scheidegger Soboll, D.; Reuters Schelin, H.

    2008-01-01

    The aim of this work was to build a phantom for quality control of stereotactic radiosurgery on linear accelerators. The outward appearance is a translucent human head filled with water and enclosing an insert with test objects of known shapes. The phantom was submitted to computerized tomography, magnetic resonance imaging and angiography exams, in order to perform a radiosurgery planning. Contours of the internal structures on the therapy planning system were drawn over the MRI images. Through the image fusion of CT and MRI, the contour data was transferred to CT images. Stereotactic registration of CT and angiography was made. One isocenter treatment was created, and using the stereotactic coordinates given by the therapy planning system, the phantom was placed on a linac. X-ray images were performed in order to verify the final positioning of the planned isocenter. In the whole process the phantom showed usefulness and adequacy for the positioning quality control of stereotactic radiosurgery with linacs, according to the main documents concerning the issue. (author)

  4. Original Research Human papillomavirus in head and neck ...

    African Journals Online (AJOL)

    2017 The College of Medicine and the Medical Association of Malawi. This work is ... Original Research. Human ... simultaneous evaluation of other risk factors including HIV ..... increased HNSCC compared to HIV-negative people.18,19.

  5. Metaproteomic analysis of human gut microbiota: where are we heading?

    Science.gov (United States)

    Lee, Pey Yee; Chin, Siok-Fong; Neoh, Hui-Min; Jamal, Rahman

    2017-06-12

    The human gut is home to complex microbial populations that change dynamically in response to various internal and external stimuli. The gut microbiota provides numerous functional benefits that are crucial for human health but in the setting of a disturbed equilibrium, the microbial community can cause deleterious outcomes such as diseases and cancers. Characterization of the functional activities of human gut microbiota is fundamental to understand their roles in human health and disease. Metaproteomics, which refers to the study of the entire protein collection of the microbial community in a given sample is an emerging area of research that provides informative details concerning functional aspects of the microbiota. In this mini review, we present a summary of the progress of metaproteomic analysis for studying the functional role of gut microbiota. This is followed by an overview of the experimental approaches focusing on fecal specimen for metaproteomics and is concluded by a discussion on the challenges and future directions of metaproteomic research.

  6. A structurally detailed finite element human head model for simulation of transcranial magnetic stimulation.

    Science.gov (United States)

    Chen, Ming; Mogul, David Jeffery

    2009-04-30

    Computational studies of the head utilizing finite element models (FEMs) have been used to investigate a wide variety of brain-electromagnetic (EM) field interaction phenomena including magnetic stimulation of the head using transcranial magnetic stimulation (TMS), direct electric stimulation of the brain for electroconvulsive therapy, and electroencephalography source localization. However, no human head model of sufficient complexity for studying the biophysics under these circumstances has been developed which utilizes structures at both the regional and cellular levels and provides well-defined smooth boundaries between tissues of different conductivities and orientations. The main barrier for building such accurate head models is the complex modeling procedures that include 3D object reconstruction and optimized meshing. In this study, a structurally detailed finite element model of the human head was generated that includes details to the level of cerebral gyri and sulci by combining computed tomography and magnetic resonance images. Furthermore, cortical columns that contain conductive processes of pyramidal neurons traversing the neocortical layers were included in the head model thus providing structure at or near the cellular level. These refinements provide a much more realistic model to investigate the effects of TMS on brain electrophysiology in the neocortex.

  7. Genotyping of human lice suggests multiple emergencies of body lice from local head louse populations.

    Directory of Open Access Journals (Sweden)

    Wenjun Li

    Full Text Available BACKGROUND: Genetic analyses of human lice have shown that the current taxonomic classification of head lice (Pediculus humanus capitis and body lice (Pediculus humanus humanus does not reflect their phylogenetic organization. Three phylotypes of head lice A, B and C exist but body lice have been observed only in phylotype A. Head and body lice have different behaviours and only the latter have been involved in outbreaks of infectious diseases including epidemic typhus, trench fever and louse borne recurrent fever. Recent studies suggest that body lice arose several times from head louse populations. METHODS AND FINDINGS: By introducing a new genotyping technique, sequencing variable intergenic spacers which were selected from louse genomic sequence, we were able to evaluate the genotypic distribution of 207 human lice. Sequence variation of two intergenic spacers, S2 and S5, discriminated the 207 lice into 148 genotypes and sequence variation of another two intergenic spacers, PM1 and PM2, discriminated 174 lice into 77 genotypes. Concatenation of the four intergenic spacers discriminated a panel of 97 lice into 96 genotypes. These intergenic spacer sequence types were relatively specific geographically, and enabled us to identify two clusters in France, one cluster in Central Africa (where a large body louse outbreak has been observed and one cluster in Russia. Interestingly, head and body lice were not genetically differentiated. CONCLUSIONS: We propose a hypothesis for the emergence of body lice, and suggest that humans with both low hygiene and head louse infestations provide an opportunity for head louse variants, able to ingest a larger blood meal (a required characteristic of body lice, to colonize clothing. If this hypothesis is ultimately supported, it would help to explain why poor human hygiene often coincides with outbreaks of body lice. Additionally, if head lice act as a reservoir for body lice, and that any social degradation in

  8. Gastrointestinal Physiology During Head Down Tilt Bedrest in Human Subjects

    Science.gov (United States)

    Vaksman, Z.; Guthienz, J.; Putcha, L.

    2008-01-01

    Introduction: Gastrointestinal (GI) motility plays a key role in the physiology and function of the GI tract. It directly affects absorption of medications and nutrients taken by mouth, in addition to indirectly altering GI physiology by way of changes in the microfloral composition and biochemistry of the GI tract. Astronauts have reported nausea, loss of appetite and constipation during space flight all of which indicate a reduction in GI motility and function similar to the one seen in chronic bed rest patients. The purpose of this study is to determine GI motility and bacterial proliferation during -6 degree head down tilt bed rest (HTD). Methods: Healthy male and female subjects between the ages of 25-40 participated in a 60 day HTD study protocol. GI transit time (GITT) was determined using lactulose breath hydrogen test and bacterial overgrowth was measured using glucose breath hydrogen test. H. Pylori colonization was determined using C13-urea breath test (UBIT#). All three tests were conducted on 9 days before HDT, and repeated on HDT days 2, 28, 58, and again on day 7 after HDT. Results: GITT increased during HTD compared to the respective ambulatory control values; GITT was significantly lower on day 7 after HTD. A concomitant increase in bacterial colonization was also noticed during HDT starting after approximately 28 days of HDT. However, H. Pylori proliferation was not recorded during HDT as indicated by UBIT#. Conclusion: GITT significantly decreased during HDT with a concomitant increase in the proliferation of GI bacterial flora but not H. pylori.

  9. SU-F-T-114: A Novel Anatomically Predictive Extension Model of Computational Human Phantoms for Dose Reconstruction in Retrospective Epidemiological Studies of Second Cancer Risks in Radiotherapy Patients

    International Nuclear Information System (INIS)

    Kuzmin, G; Lee, C; Lee, C; Pelletier, C; Jung, J

    2016-01-01

    Purpose: Recent advances in cancer treatments have greatly increased the likelihood of post-treatment patient survival. Secondary malignancies, however, have become a growing concern. Epidemiological studies determining secondary effects in radiotherapy patients require assessment of organ-specific dose both inside and outside the treatment field. An essential input for Monte Carlo modeling of particle transport is radiological images showing full patient anatomy. However, in retrospective studies it is typical to only have partial anatomy from CT scans used during treatment planning. In this study, we developed a multi-step method to extend such limited patient anatomy to full body anatomy for estimating dose to normal tissues located outside the CT scan coverage. Methods: The first step identified a phantom from a library of body size-dependent computational human phantoms by matching the height and weight of patients. Second, a Python algorithm matched the patient CT coverage location in relation to the whole body phantom. Third, an algorithm cut the whole body phantom and scaled them to match the size of the patient. Then, merged the two anatomies into one whole body. We entitled this new approach, Anatomically Predictive Extension (APE). Results: The APE method was examined by comparing the original chest-abdomen-pelvis CT images of the five patients with the APE phantoms developed from only the chest part of the CAP images and whole body phantoms. We achieved average percent differences of tissue volumes of 25.7%, 34.2%, 16.5%, 26.8%, and 31.6% with an average of 27% across all patients. Conclusion: Our APE method extends the limited CT patient anatomy to whole body anatomy by using image processing and computational human phantoms. Our ongoing work includes evaluating the accuracy of these APE phantoms by comparing normal tissue doses in the APE phantoms and doses calculated for the original full CAP images under generic radiotherapy simulations. This

  10. SU-F-T-114: A Novel Anatomically Predictive Extension Model of Computational Human Phantoms for Dose Reconstruction in Retrospective Epidemiological Studies of Second Cancer Risks in Radiotherapy Patients

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmin, G; Lee, C [National Cancer Institute, Rockville, MD (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Pelletier, C; Jung, J [East Carolina University Greenville, NC (United States)

    2016-06-15

    Purpose: Recent advances in cancer treatments have greatly increased the likelihood of post-treatment patient survival. Secondary malignancies, however, have become a growing concern. Epidemiological studies determining secondary effects in radiotherapy patients require assessment of organ-specific dose both inside and outside the treatment field. An essential input for Monte Carlo modeling of particle transport is radiological images showing full patient anatomy. However, in retrospective studies it is typical to only have partial anatomy from CT scans used during treatment planning. In this study, we developed a multi-step method to extend such limited patient anatomy to full body anatomy for estimating dose to normal tissues located outside the CT scan coverage. Methods: The first step identified a phantom from a library of body size-dependent computational human phantoms by matching the height and weight of patients. Second, a Python algorithm matched the patient CT coverage location in relation to the whole body phantom. Third, an algorithm cut the whole body phantom and scaled them to match the size of the patient. Then, merged the two anatomies into one whole body. We entitled this new approach, Anatomically Predictive Extension (APE). Results: The APE method was examined by comparing the original chest-abdomen-pelvis CT images of the five patients with the APE phantoms developed from only the chest part of the CAP images and whole body phantoms. We achieved average percent differences of tissue volumes of 25.7%, 34.2%, 16.5%, 26.8%, and 31.6% with an average of 27% across all patients. Conclusion: Our APE method extends the limited CT patient anatomy to whole body anatomy by using image processing and computational human phantoms. Our ongoing work includes evaluating the accuracy of these APE phantoms by comparing normal tissue doses in the APE phantoms and doses calculated for the original full CAP images under generic radiotherapy simulations. This

  11. Temperature changes associated with radiofrequency exposure near authentic metallic implants in the head phantom--a near field simulation study with 900, 1800 and 2450 MHz dipole.

    Science.gov (United States)

    Matikka Virtanen, H; Keshvari, J; Lappalainen, R

    2010-10-07

    Along with increased use of wireless communication devices operating in the radiofrequency (RF) range, concern has been raised about the related possible health risks. Among other concerns, the interaction of medical implants and RF devices has been studied in order to assure the safety of implant carriers under various exposure conditions. In the RF range, the main established quantitative effect of electromagnetic (EM) fields on biological tissues is heating due to vibrational movements of water molecules. The temperature changes induced in tissues also constitute the basis for the setting of RF exposure limits and recommendations. In this study, temperature changes induced by electromagnetic field enhancements near passive metallic implants have been simulated in the head region. Furthermore, the effect of the implant material on the induced temperature change was evaluated using clinically used metals with the highest and the lowest thermal conductivities. In some cases, remarkable increases in maximum temperatures of tissues (as much as 8 °C) were seen in the near field with 1 W power level whereas at lower power levels significant temperature increases were not observed.

  12. Estimation of dose enhancement to soft tissue due to backscatter radiation near metal interfaces during head and neck radiothearpy - A phantom dosimetric study with radiochromic film

    Directory of Open Access Journals (Sweden)

    Rajesh Ashok Kinhikar

    2014-01-01

    Full Text Available The objective of this study was to investigate the dose enhancement to soft tissue due to backscatter radiation near metal interfaces during head and neck radiotherapy. The influence of titanium-mandibular plate with the screws on radiation dose was tested on four real bones from mandible with the metal and screws fixed. Radiochromic films were used for dosimetry. The bone and metal were inserted through the film at the center symmetrically. This was then placed in a small jig (7 cm × 7 cm × 10 cm to hold the film vertically straight. The polymer granules (tissue-equivalent were placed around the film for homogeneous scatter medium. The film was irradiated with 6 MV X-rays for 200 monitor units in Trilogy linear accelerator for 10 cm × 10 cm field size with source to axis distance of 100 cm at 5 cm. A single film was also irradiated without any bone and metal interface for reference data. The absolute dose and the vertical dose profile were measured from the film. There was 10% dose enhancement due to the backscatter radiation just adjacent to the metal-bone interface for all the materials. The extent of the backscatter effect was up to 4 mm. There is significant higher dose enhancement in the soft tissue/skin due to the backscatter radiation from the metallic components in the treatment region.

  13. The Japanese adult, child and infant phantoms

    International Nuclear Information System (INIS)

    Cristy, Mark; Egbert, Stephen D.

    1987-01-01

    The mathematical phantom for adult Japanese atomic-bomb survivors is a modification of the 57-kg ORNL (Oak Ridge National Laboratory) phantom for Western 15-year-old males and adult females. For younger Japanese survivors mathematical phantoms were similarly modified from the 18 and 9 kg ORNL phantoms for Western 5- and 1-year-olds, respectively. To make the phantom correspond more closely with dimensions and organ sizes recommended for Japanese adults by Maruyama and coworkers (cf E184), changes were made in the size of the lungs, the pancreas, the thyroid, and the testes and in the length of the legs. Also, the head-and-neck region was modified to improve the dose estimates for the thyroid from external radiation, after the ideas of Nagarajan et al. The arms were separated from the trunk to represent more accurately the shielding by the phantom in external exposures. Furthermore, provisions were made to provide a phantom in a kneeling posture. The elemental composition of the tissues was changed to that given by Kerr. The resulting phantom is slightly smaller in mass (55 kg). Details of these changes are given

  14. Patient specific 3D printed phantom for IMRT quality assurance

    International Nuclear Information System (INIS)

    Ehler, Eric D; Higgins, Patrick D; Dusenbery, Kathryn E; Barney, Brett M

    2014-01-01

    The purpose of this study was to test the feasibility of a patient specific phantom for patient specific dosimetric verification. Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. Calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was compared for a parallel-opposed head and neck field geometry to establish tissue equivalence. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom as well as traditional standard phantoms. The maximum difference in calculated dose was 1.8% for the parallel-opposed configuration. Passing rates of various dosimetric parameters were compared for the IMRT plan measurements; the 3D printed phantom results showed greater disagreement at superficial depths than other methods. A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine use. (paper)

  15. Effective dose evaluation of NORM-added consumer products using Monte Carlo simulations and the ICRP computational human phantoms.

    Science.gov (United States)

    Lee, Hyun Cheol; Yoo, Do Hyeon; Testa, Mauro; Shin, Wook-Geun; Choi, Hyun Joon; Ha, Wi-Ho; Yoo, Jaeryong; Yoon, Seokwon; Min, Chul Hee

    2016-04-01

    The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1mSv y(-1) for 44 products. It was demonstrated that NORM-added consumer products could be quantitatively assessed for the safety regulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. The calculation of dose from external photon exposures using reference human phantoms and Monte-Carlo methods. Pt. 1

    International Nuclear Information System (INIS)

    Kramer, R.; Zankl, M.; Williams, G.; Drexler, G.

    1982-12-01

    By the help of a Monte-Carlo program the dose that single organs, organ groups and bigger or smaller parts of body would receive on an average, caused by an irradiation definitely fixed by the geometry of irradiation and photon energy, can be determined. Thus the phantom in connection with the Monte-Carlo program can be used for several considerations as for example - calculation of dose from occupational exposures - calculation of dose from diagnostic procedures - calculation of dose from radiotherapy procedures. (orig.)

  17. The response of some health physics instruments to sodium-24 and chlorine-38 activities in polythene man-phantoms and the human body

    International Nuclear Information System (INIS)

    Peabody, C.O.

    1963-12-01

    Measurements have been made of the response of five commonly used Health Physics instruments when held near polythene man-phantoms filled with aqueous solutions containing sodium-24 and chlorine-38 activities. The instruments discussed are the Type 1413A, 1597A and 1368A ratemeters, the E.M.I. PCM1 contamination monitor and the Type 1021C beta-gamma probe. The ratios of the whole-body chlorine-38 and sodium-24 activities are calculated for various periods of accidental human irradiation by neutrons. These ratios and the phantom results are used to estimate the response of the five instruments when held near the human body at various times after irradiation. The relative contributions of the chlorine-38 and sodium-24 to the instrument indications are listed. The tabulated data enable the instrument readings to be converted to whole-body sodium-24 activity at the time of irradiation. This may be used as a quick estimate of the degree of neutron irradiation. (author)

  18. Computational anthropomorphic phantoms for radiation protection dosimetry: evolution and prospects

    International Nuclear Information System (INIS)

    Lee, Choonsik; Lee, Jaiki

    2006-01-01

    Computational anthropomorphic phantoms are computer models of human anatomy used in the calculation of radiation dose distribution in the human body upon exposure to a radiation source. Depending on the manner to represent human anatomy, they are categorized into two classes: stylized and tomographic phantoms. Stylized phantoms, which have mainly been developed at the Oak Ridge National Laboratory (ORNL), describe human anatomy by using simple mathematical equations of analytical geometry. Several improved stylized phantoms such as male and female adults, pediatric series, and enhanced organ models have been developed following the first hermaphrodite adult stylized phantom, Medical Internal Radiation Dose (MIRD)-5 phantom. Although stylized phantoms have significantly contributed to dosimetry calculation, they provide only approximations of the true anatomical features of the human body and the resulting organ dose distribution. An alternative class of computational phantom, the tomographic phantom, is based upon three-dimensional imaging techniques such as Magnetic Resonance (MR) imaging and Computed Tomography (CT). The tomographic phantoms represent the human anatomy with a large number of voxels that are assigned tissue type and organ identity. To date, a total of around 30 tomographic phantoms including male and female adults, pediatric phantoms, and even a pregnant female, have been developed and utilized for realistic radiation dosimetry calculation. They are based on MRI/CT images or sectional color photos from patients, volunteers or cadavers. Several investigators have compared tomographic phantoms with stylized phantoms, and demonstrated the superiority of tomographic phantoms in terms of realistic anatomy and dosimetry calculation. This paper summarizes the history and current status of both stylized and tomographic phantoms, including Korean computational phantoms. Advantages, limitations, and future prospects are also discussed

  19. Everyman's prostate phantom: kiwi-fruit substitute for human prostates at magnetic resonance imaging, diffusion-weighted imaging and magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Lisse, Ullrich G.; Murer, Sophie; Kuhn, Marissa [University of Munich (' ' Ludwig-Maximilians-Universitaet' ' , LMU), Department of Radiology, Faculty of Medicine, Muenchen (Germany); Mueller-Lisse, Ulrike L. [University of Munich (' ' Ludwig-Maximilians-Universitaet' ' , LMU), Department of Urology, Faculty of Medicine, Muenchen (Germany); Interdisciplinary Oncology Centre Munich (IOZ), Department of Urology, Munich (Germany); Scheidler, Juergen [University of Munich (' ' Ludwig-Maximilians-Universitaet' ' , LMU), Department of Radiology, Faculty of Medicine, Muenchen (Germany); Radiology Centre Munich (RZM), Muenchen (Germany); Scherr, Michael [University of Munich (' ' Ludwig-Maximilians-Universitaet' ' , LMU), Department of Radiology, Faculty of Medicine, Muenchen (Germany); BG Unfallklinik Murnau, Department of Radiology, Murnau am Staffelsee (Germany)

    2017-08-15

    To apply an easy-to-assemble phantom substitute for human prostates in T2-weighted magnetic resonance imaging (T2WI), diffusion-weighted imaging (DWI) and 3D magnetic resonance spectroscopy (MRS). Kiwi fruit were fixed with gel hot and cold compress packs on two plastic nursery pots, separated by a plastic plate, and submerged in tap water inside a 1-L open-spout plastic watering can for T2WI (TR/TE 7500/101 ms), DWI (5500/61 ms, ADC b50-800 s/mm{sup 2} map) and MRS (940/145 ms) at 3.0 T, with phased array surface coils. One green kiwi fruit was additionally examined with an endorectal coil. Retrospective comparison with benign peripheral zone (PZ) and transitional zone (TZ) of prostate (n = 5), Gleason 6-7a prostate cancer (n = 8) and Gleason 7b-9 prostate cancer (n = 7) validated the phantom. Mean contrast between central placenta (CP) and outer pericarp (OP, 0.346-0.349) or peripheral placenta (PP, 0.364-0.393) of kiwi fruit was similar to Gleason 7b-9 prostate cancer and PZ (0.308) in T2WI. ADC values of OP and PP (1.27 ± 0.07-1.37 ± 0.08 mm{sup 2}/s x 10{sup -3}) resembled PZ and TZ (1.39 ± 0.17-1.60 ± 0.24 mm{sup 2}/s x 10{sup -3}), while CP (0.91 ± 0.14-0.99 ± 0.10 mm{sup 2}/s x 10{sup -3}) resembled Gleason 7b-9 prostate cancer (1.00 ± 0.25 mm{sup 2}/s x 10{sup -3}). MR spectra showed peaks of citrate and myo-inositol in kiwi fruit, and citrate and ''choline+creatine'' in prostates. The phantom worked with an endorectal coil, too. The kiwi fruit phantom reproducibly showed zones similar to PZ, TZ and cancer in human prostates in T2WI and DWI and two metabolite peaks in MRS and appears suitable to compare different MR protocols, coil systems and scanners. (orig.)

  20. Muecas: A Multi-Sensor Robotic Head for Affective Human Robot Interaction and Imitation

    Directory of Open Access Journals (Sweden)

    Felipe Cid

    2014-04-01

    Full Text Available This paper presents a multi-sensor humanoid robotic head for human robot interaction. The design of the robotic head, Muecas, is based on ongoing research on the mechanisms of perception and imitation of human expressions and emotions. These mechanisms allow direct interaction between the robot and its human companion through the different natural language modalities: speech, body language and facial expressions. The robotic head has 12 degrees of freedom, in a human-like configuration, including eyes, eyebrows, mouth and neck, and has been designed and built entirely by IADeX (Engineering, Automation and Design of Extremadura and RoboLab. A detailed description of its kinematics is provided along with the design of the most complex controllers. Muecas can be directly controlled by FACS (Facial Action Coding System, the de facto standard for facial expression recognition and synthesis. This feature facilitates its use by third party platforms and encourages the development of imitation and of goal-based systems. Imitation systems learn from the user, while goal-based ones use planning techniques to drive the user towards a final desired state. To show the flexibility and reliability of the robotic head, the paper presents a software architecture that is able to detect, recognize, classify and generate facial expressions in real time using FACS. This system has been implemented using the robotics framework, RoboComp, which provides hardware-independent access to the sensors in the head. Finally, the paper presents experimental results showing the real-time functioning of the whole system, including recognition and imitation of human facial expressions.

  1. Development of a head phantom to be used for quality control in stereotactic radiosurgery; Desenvolvimento de um simulador de cabeca para a aplicacao no controle da qualidade de radiocirurgia estereotaxica

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Nilseia Aparecida

    2010-05-15

    It was designed and developed a geometric acrylic head phantom (GHP) for Quality Assurance (QA) in Stereotactic Radiosurgery (SRS). Inside the phantom there are inserts that are able to accommodate acrylic targets representing the tumor tissue and organ at risk in the region cranial brain, the brain stem. The tumor tissue is represented by two semi-spheres of acrylic with a diameter of 13.0 mm and cavities in the central region for accommodation of a TLD-100 detector and a small radiochromic EBT Gafchromic filmstrip. The brain stem is represented by the two parts of acrylic cylinder with a diameter 18.0 mm, 38.0 mm length and cavities along the central region to accommodate the 5 detectors TLD-100 and yet another of EBT film. The distance tumor - brain stem is 2.0 mm. The experimental setup was filled with water, attached to the stereotactic frame to determine the coordinates of the target and underwent computed tomography (CT). Cf images were transferred to the SRS planning system BrainLab (BrainScan). The contours of the lesion and organ at risk were delineated and, through the technique of multiple circular arcs, the planning was conduced with five arches, one isocenter and a collimator of 17.5 mm from the combination between the table and gantry . The dose delivered to the isocenter of the lesion was 3.0 Gy and the total coverage of tumor volume corresponds to the 75% isodose. This experimental arrangement is subjected to radiosurgery treatment, after which the dosimeters are evaluated and their responses compared with the values of planned doses. The linear accelerator used was a Varian CLlNAC 2300 CID, photon beam of 6 MV, installed at the National Cancer Institute (INCA). For verification of dose distributions in 3D, the films were irradiated in three planes: sagittal, caronal and axial. The .films were scanned and digitized on a scanner Microtek ScanMaker 9800XL model. The dose distributions in irradiated films were compared with the distributions of doses

  2. Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners.

    Science.gov (United States)

    Lin, James C; Wang, Zhangwei

    2010-04-01

    The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea.

  3. Phantom atom

    International Nuclear Information System (INIS)

    Ludwig, K.; Voigt, S.

    1993-01-01

    The Society for People Living under Threat has been supporting those affected by radiation (Uranium decay), nuclear weapons testing, nuclear power stations and waste disposal since the mid-sixties. Through a great number of meetings, press releases and campaigns, it has succeeded in bringing the theme into the public spotlight in Germany, particularly within the ecology movement. The initial hesitation in supporting the indigenous peoples threatened by radiation contamination has given way to broad consensus and support. The ecology and human rights movement have united the need to listen to and give support to those of whom no-one speaks. (orig./DG) [de

  4. The role of Human papillomavirus in head and neck cancer and the impact on radiotherapy outcome

    International Nuclear Information System (INIS)

    Lassen, Pernille

    2010-01-01

    The profound influence of Human papillomavirus (HPV) on the epidemiological pattern and clinical course of head and neck cancer (HNSCC) has led to a change in the traditional understanding of this disease entity. Separate therapeutic strategies based on tumour HPV status are under consideration and in this light provision of knowledge concerning the influence of tumour HPV on the radiation response in HNSCC appears highly relevant. This review provides a summary of the current understanding of the role of HPV in head and neck cancer with specific focus on the viral impact on radiotherapy outcome of HNSCC.

  5. Evolution of dosimetric phantoms

    International Nuclear Information System (INIS)

    Reddy, A.R.

    2010-01-01

    In this oration evolution of the dosimetric phantoms for radiation protection and for medical use is briefly reviewed. Some details of the development of Indian Reference Phantom for internal dose estimation are also presented

  6. Analysis of two colliding fractionally damped spherical shells in modelling blunt human head impacts

    Science.gov (United States)

    Rossikhin, Yury A.; Shitikova, Marina V.

    2013-06-01

    The collision of two elastic or viscoelastic spherical shells is investigated as a model for the dynamic response of a human head impacted by another head or by some spherical object. Determination of the impact force that is actually being transmitted to bone will require the model for the shock interaction of the impactor and human head. This model is indended to be used in simulating crash scenarios in frontal impacts, and provide an effective tool to estimate the severity of effect on the human head and to estimate brain injury risks. The model developed here suggests that after the moment of impact quasi-longitudinal and quasi-transverse shock waves are generated, which then propagate along the spherical shells. The solution behind the wave fronts is constructed with the help of the theory of discontinuities. It is assumed that the viscoelastic features of the shells are exhibited only in the contact domain, while the remaining parts retain their elastic properties. In this case, the contact spot is assumed to be a plane disk with constant radius, and the viscoelastic features of the shells are described by the fractional derivative standard linear solid model. In the case under consideration, the governing differential equations are solved analytically by the Laplace transform technique. It is shown that the fractional parameter of the fractional derivative model plays very important role, since its variation allows one to take into account the age-related changes in the mechanical properties of bone.

  7. An improved Virtual Torso phantom

    International Nuclear Information System (INIS)

    Kramer, Gary H; Crowley, Paul

    2000-01-01

    The virtual phantom that was previously designed by the Human Monitoring Laboratory had some limitations. It contained no sternum and the ribs extended all the way round the torso, whereas in reality the central part of the chest is covered with a mixture of cartilage (ribs) and bone (sternum). The ribs were located below the chest wall which added to the thickness of the chest wall. The lungs did not touch the inner surface of the chest wall along their length due to the differences in curvature between the ellipsoidal lungs and the ellipsoidal cylinder that defined the torso. As a result there was extra intervening tissue between the lungs and the chest wall. This was shown to have a noticeable effect on the simulation of low energy photons. The virtual phantom has been redesigned and comparison of measured and calculated counting efficiencies shows that it is a good representation of both of LLNL or JAERI at all photon energies measured. The redesigned virtual phantom agrees to within 11% of the torsos' counting efficiency over the energy range 17 - 240 keV. Before modification, the virtual phantom's counting efficiency was a of factor three lower at 17 keV and a factor of two lower at 20 keV; now it is within 5% at 17 keV and within 10% at 20 keV. This phantom can now be reliably used to simulate lung counting. The virtual phantom still contains no sternum and the ribs extend all the way round the torso, whereas in reality the central part of the chest is covered with cartilage (ribs) and bone (sternum). However, the above results indicate that this is not a major flaw in the design of the virtual phantom, as agreement between the Monte Carlo results and experimental data is good. (author)

  8. Channel heads in mountain catchments subject to human impact - The Skrzyczne range in Southern Poland

    Science.gov (United States)

    Wrońska-Wałach, Dominika; Żelazny, Mirosław; Małek, Stanisław; Krakowian, Katarzyna; Dąbek, Natalia

    2018-05-01

    Channel heads in mountain catchments are increasingly influenced by human activity. The disturbance of mountain headwater areas in moderate latitudes by the clearing of trees and the associated logging, road building and hydrotechnical constructions contribute to changes in the water cycle and consequently may induce a change in channel head development. Here we examine channel heads in the Beskid Śląski Mts., one of the areas most affected by ecological disaster in the Polish Flysch Carpathians. An ecological disaster associated with the decline of spruce trees in the 1980s and 1990s caused a substantial decrease (of about 50%) in the land area occupied by spruce forest in the Beskid Śląski Mts. As a result, headwater areas were subject to multidirectional changes in the environment. The purpose of this paper is to determine the detailed characteristics of channel heads currently developing in the analyzed headwater areas, as well as to identify independent factors that affect the evolution of channel heads. Geomorphological mapping was conducted in 2012 in the vicinity of springs in the study area. One-way ANOVA was used to determine the significance of differences between mean values calculated for groups identified based on: i) geomorphologic processes (hollows with rock veneer - h, spring niches - sn, gullies - g), ii) location vs. transformation of channel heads (forested areas vs., deforested areas with road constructions). Principal component analysis (PCA) was used to determine the structure and general patterns associated with relationships between the parameters of a channel head and its contribution area, as well as to identify and interpret new (orthogonal) spaces defined using distinct factors. As far as we know, this kind of approach has been never applied before. A total of 80 channel heads surrounding 104 springs were surveyed close to the main ridge in the study area. A total of 14 morphometric parameters were taken into account in this study

  9. Human Papillomavirus Induced Transformation in Cervical and Head and Neck Cancers

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Allie K. [Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229 (United States); Wise-Draper, Trisha M. [Division of Hematology/Oncology, University of Cincinnati Medical Center, University of Cincinnati, Cincinnati, OH 45229 (United States); Wells, Susanne I., E-mail: Susanne.Wells@cchmc.org [Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229 (United States)

    2014-09-15

    Human papillomavirus (HPV) is one of the most widely publicized and researched pathogenic DNA viruses. For decades, HPV research has focused on transforming viral activities in cervical cancer. During the past 15 years, however, HPV has also emerged as a major etiological agent in cancers of the head and neck, in particular squamous cell carcinoma. Even with significant strides achieved towards the screening and treatment of cervical cancer, and preventive vaccines, cervical cancer remains the leading cause of cancer-associated deaths for women in developing countries. Furthermore, routine screens are not available for those at risk of head and neck cancer. The current expectation is that HPV vaccination will prevent not only cervical, but also head and neck cancers. In order to determine if previous cervical cancer models for HPV infection and transformation are directly applicable to head and neck cancer, clinical and molecular disease aspects must be carefully compared. In this review, we briefly discuss the cervical and head and neck cancer literature to highlight clinical and genomic commonalities. Differences in prognosis, staging and treatment, as well as comparisons of mutational profiles, viral integration patterns, and alterations in gene expression will be addressed.

  10. Human Papillomavirus Induced Transformation in Cervical and Head and Neck Cancers

    International Nuclear Information System (INIS)

    Adams, Allie K.; Wise-Draper, Trisha M.; Wells, Susanne I.

    2014-01-01

    Human papillomavirus (HPV) is one of the most widely publicized and researched pathogenic DNA viruses. For decades, HPV research has focused on transforming viral activities in cervical cancer. During the past 15 years, however, HPV has also emerged as a major etiological agent in cancers of the head and neck, in particular squamous cell carcinoma. Even with significant strides achieved towards the screening and treatment of cervical cancer, and preventive vaccines, cervical cancer remains the leading cause of cancer-associated deaths for women in developing countries. Furthermore, routine screens are not available for those at risk of head and neck cancer. The current expectation is that HPV vaccination will prevent not only cervical, but also head and neck cancers. In order to determine if previous cervical cancer models for HPV infection and transformation are directly applicable to head and neck cancer, clinical and molecular disease aspects must be carefully compared. In this review, we briefly discuss the cervical and head and neck cancer literature to highlight clinical and genomic commonalities. Differences in prognosis, staging and treatment, as well as comparisons of mutational profiles, viral integration patterns, and alterations in gene expression will be addressed

  11. WE-EF-303-06: Feasibility of PET Image-Based On-Line Proton Beam-Range Verification with Simulated Uniform Phantom and Human Brain Studies

    International Nuclear Information System (INIS)

    Lou, K; Sun, X; Zhu, X; Grosshans, D; Clark, J; Shao, Y

    2015-01-01

    Purpose: To study the feasibility of clinical on-line proton beam range verification with PET imaging Methods: We simulated a 179.2-MeV proton beam with 5-mm diameter irradiating a PMMA phantom of human brain size, which was then imaged by a brain PET with 300*300*100-mm 3 FOV and different system sensitivities and spatial resolutions. We calculated the mean and standard deviation of positron activity range (AR) from reconstructed PET images, with respect to different data acquisition times (from 5 sec to 300 sec with 5-sec step). We also developed a technique, “Smoothed Maximum Value (SMV)”, to improve AR measurement under a given dose. Furthermore, we simulated a human brain irradiated by a 110-MeV proton beam of 50-mm diameter with 0.3-Gy dose at Bragg peak and imaged by the above PET system with 40% system sensitivity at the center of FOV and 1.7-mm spatial resolution. Results: MC Simulations on the PMMA phantom showed that, regardless of PET system sensitivities and spatial resolutions, the accuracy and precision of AR were proportional to the reciprocal of the square root of image count if image smoothing was not applied. With image smoothing or SMV method, the accuracy and precision could be substantially improved. For a cylindrical PMMA phantom (200 mm diameter and 290 mm long), the accuracy and precision of AR measurement could reach 1.0 and 1.7 mm, with 100-sec data acquired by the brain PET. The study with a human brain showed it was feasible to achieve sub-millimeter accuracy and precision of AR measurement with acquisition time within 60 sec. Conclusion: This study established the relationship between count statistics and the accuracy and precision of activity-range verification. It showed the feasibility of clinical on-line BR verification with high-performance PET systems and improved AR measurement techniques. Cancer Prevention and Research Institute of Texas grant RP120326, NIH grant R21CA187717, The Cancer Center Support (Core) Grant CA016672

  12. Wavelet-based resolution recovery using an anatomical prior provides quantitative recovery for human population phantom PET [11C]raclopride data

    International Nuclear Information System (INIS)

    Shidahara, M; Tamura, H; Tsoumpas, C; McGinnity, C J; Hammers, A; Turkheimer, F E; Kato, T; Watabe, H

    2012-01-01

    The objective of this study was to evaluate a resolution recovery (RR) method using a variety of simulated human brain [ 11 C]raclopride positron emission tomography (PET) images. Simulated datasets of 15 numerical human phantoms were processed by a wavelet-based RR method using an anatomical prior. The anatomical prior was in the form of a hybrid segmented atlas, which combined an atlas for anatomical labelling and a PET image for functional labelling of each anatomical structure. We applied RR to both 60 min static and dynamic PET images. Recovery was quantified in 84 regions, comparing the typical ‘true’ value for the simulation, as obtained in normal subjects, simulated and RR PET images. The radioactivity concentration in the white matter, striatum and other cortical regions was successfully recovered for the 60 min static image of all 15 human phantoms; the dependence of the solution on accurate anatomical information was demonstrated by the difficulty of the technique to retrieve the subthalamic nuclei due to mismatch between the two atlases used for data simulation and recovery. Structural and functional synergy for resolution recovery (SFS-RR) improved quantification in the caudate and putamen, the main regions of interest, from −30.1% and −26.2% to −17.6% and −15.1%, respectively, for the 60 min static image and from −51.4% and −38.3% to −27.6% and −20.3% for the binding potential (BP ND ) image, respectively. The proposed methodology proved effective in the RR of small structures from brain [ 11 C]raclopride PET images. The improvement is consistent across the anatomical variability of a simulated population as long as accurate anatomical segmentations are provided. (paper)

  13. Verification of CTDI and Dlp values for a head tomography reported by the manufacturers of the CT scanners, using a CT dose profiler probe, a head phantom and a piranha electrometer

    International Nuclear Information System (INIS)

    Castillo C, E.; Garcia F, I. B.; Garcia H, J.; Roman L, S.; Salmeron C, O.

    2015-10-01

    The extensive use of Computed Tomography (CT) and the associated increase in patient dose calls for an accurate dose evaluation technique. The CT contributes up to 70% of the total dose given to patients during X-ray examinations. The rapid advancements in CT technology are placing new demands on the methods and equipment that are used for quality assurance. The wide beam widths found in CT scanners with multiple beam apertures make it impossible to use existing CT ionization chambers to measure the total dose given to the patient. Using a standard 10 cm CT ionization chamber may result in inaccurate measurements due to underestimation of the dose profile for wide beams. The use a CT dose profiler based on solid-state technology and the Piranha electrometer from RTI electronics provides a potential solution to the arising concerns over patient dose. This study intend to evaluate the feasibility and accuracy of CT Dose Index (CTDI) and Dose Length Product (Dlp) values for a head tomography reported by the manufacturers of the CT scanners at each study. (Author)

  14. Verification of CTDI and Dlp values for a head tomography reported by the manufacturers of the CT scanners, using a CT dose profiler probe, a head phantom and a piranha electrometer

    Energy Technology Data Exchange (ETDEWEB)

    Castillo C, E.; Garcia F, I. B.; Garcia H, J.; Roman L, S. [Servicios de Salud de Michoacan, Centro Estatal de Atencion Oncologica, Gertrudis Bocanegra No. 300, Col. Cuauhtemoc, 58020 Morelia, Michoacan (Mexico); Salmeron C, O., E-mail: edithcastillocorona@gmail.com [Servicios de Salud de Michoacan, Hospital General Dr. Miguel Silva, Isidro Huarte s/n, Centro Historico, 58000 Morelia, Michoacan (Mexico)

    2015-10-15

    The extensive use of Computed Tomography (CT) and the associated increase in patient dose calls for an accurate dose evaluation technique. The CT contributes up to 70% of the total dose given to patients during X-ray examinations. The rapid advancements in CT technology are placing new demands on the methods and equipment that are used for quality assurance. The wide beam widths found in CT scanners with multiple beam apertures make it impossible to use existing CT ionization chambers to measure the total dose given to the patient. Using a standard 10 cm CT ionization chamber may result in inaccurate measurements due to underestimation of the dose profile for wide beams. The use a CT dose profiler based on solid-state technology and the Piranha electrometer from RTI electronics provides a potential solution to the arising concerns over patient dose. This study intend to evaluate the feasibility and accuracy of CT Dose Index (CTDI) and Dose Length Product (Dlp) values for a head tomography reported by the manufacturers of the CT scanners at each study. (Author)

  15. SAR in human head model due to resonant wireless power transfer system.

    Science.gov (United States)

    Zhang, Chao; Liu, Guoqiang; Li, Yanhong; Song, Xianjin

    2016-04-29

    Efficient mid-range wireless power transfer between transmitter and the receiver has been achieved based on the magnetic resonant coupling method. The influence of electromagnetic field on the human body due to resonant wireless power transfer system (RWPT) should be taken into account during the design process of the system. To analyze the transfer performance of the RWPT system and the change rules of the specific absorption rate (SAR) in the human head model due to the RWPT system. The circuit-field coupling method for a RWPT system with consideration of the displacement current was presented. The relationship between the spiral coil parameters and transfer performance was studied. The SAR in the human head model was calculated under two different exposure conditions. A system with output power higher than 10 W at 0.2 m distance operating at a frequency of approximately 1 MHz was designed. The FEM simulation results show the peak SAR value is below the safety limit which appeared when the human head model is in front of the transmitter. The simulation results agreed well with the experimental results, which verified the validity of the analysis and design.

  16. Proteomics Analyses of Human Optic Nerve Head Astrocytes Following Biomechanical Strain*

    OpenAIRE

    Rogers, Ronan S.; Dharsee, Moyez; Ackloo, Suzanne; Sivak, Jeremy M.; Flanagan, John G.

    2011-01-01

    We investigate the role of glial cell activation in the human optic nerve caused by raised intraocular pressure, and their potential role in the development of glaucomatous optic neuropathy. To do this we present a proteomics study of the response of cultured, optic nerve head astrocytes to biomechanical strain, the magnitude and mode of strain based on previously published quantitative models. In this case, astrocytes were subjected to 3 and 12% stretches for either 2 h or 24 h. Proteomic me...

  17. Controversies surrounding Human Papilloma Virus infection, head & neck vs oral cancer, implications for prophylaxis and treatment

    OpenAIRE

    Campisi, G.; Giovannelli, L.

    2009-01-01

    Head & Neck Cancer (HNC) represents the sixth most common malignancy worldwide and it is historically linked to well-known behavioural risk factors, i.e., tobacco smoking and/or the alcohol consumption. Recently, substantial evidence has been mounting that Human Papillomavirus (HPV) infection is playing an increasing important role in oral cancer. Because of the attention and clamor surrounding oral HPV infection and related cancers, as well as the use of HPV prophylactic vaccines, in this in...

  18. Tribological changes in the articular cartilage of a human femoral head with avascular necrosis.

    Science.gov (United States)

    Seo, Eun-Min; Shrestha, Suman K; Duong, Cong-Truyen; Sharma, Ashish Ranjan; Kim, Tae-Woo; Vijayachandra, Ayyappan; Thompson, Mark S; Cho, Myung Guk; Park, Sungchan; Kim, Kwanghoon; Park, Seonghun; Lee, Sang-Soo

    2015-06-29

    The present study evaluated the tribological properties of the articular cartilage surface of the human femoral head with postcollapse stage avascular necrosis (AVN) using atomic force microscopy. The cartilage surface in the postcollapse stage AVN of the femoral head was reported to resemble those of disuse conditions, which suggests that the damage could be reversible and offers the possibilities of success of head-sparing surgeries. By comparing the tribological properties of articular cartilage in AVN with that of osteoarthritis, the authors intended to understand the cartilage degeneration mechanism and reversibility of AVN. Human femoral heads with AVN were explanted from the hip replacement surgery of four patients (60-83 years old). Nine cylindrical cartilage samples (diameter, 5 mm and height, 0.5 mm) were sectioned from the weight-bearing areas of the femoral head with AVN, and the cartilage surface was classified according to the Outerbridge Classification System (AVN0, normal; AVN1, softening and swelling; and AVN2, partial thickness defect and fissuring). Tribological properties including surface roughness and frictional coefficients and histochemistry including Safranin O and lubricin staining were compared among the three groups. The mean surface roughness Rq values of AVN cartilage increased significantly with increasing Outerbridge stages: Rq = 137 ± 26 nm in AVN0, Rq = 274 ± 49 nm in AVN1, and Rq = 452 ± 77 nm in AVN2. Significant differences in Rq were observed among different Outerbridge stages in all cases (p AVN0, μ = 0.143 ± 0.025 in AVN1, and μ = 0.171 ± 0.039 in AVN2. Similarly to the statistical analysis of surface roughness, significant statistical differences were detected between different Outerbridge stages in all cases (p AVN. The underlying mechanism of these results can be related to proteoglycan loss within the articular cartilage that is also observed in osteoarthritis. With regard to the tribological properties, the

  19. A novel device for head gesture measurement system in combination with eye-controlled human machine interface

    Science.gov (United States)

    Lin, Chern-Sheng; Ho, Chien-Wa; Chang, Kai-Chieh; Hung, San-Shan; Shei, Hung-Jung; Yeh, Mau-Shiun

    2006-06-01

    This study describes the design and combination of an eye-controlled and a head-controlled human-machine interface system. This system is a highly effective human-machine interface, detecting head movement by changing positions and numbers of light sources on the head. When the users utilize the head-mounted display to browse a computer screen, the system will catch the images of the user's eyes with CCD cameras, which can also measure the angle and position of the light sources. In the eye-tracking system, the program in the computer will locate each center point of the pupils in the images, and record the information on moving traces and pupil diameters. In the head gesture measurement system, the user wears a double-source eyeglass frame, so the system catches images of the user's head by using a CCD camera in front of the user. The computer program will locate the center point of the head, transferring it to the screen coordinates, and then the user can control the cursor by head motions. We combine the eye-controlled and head-controlled human-machine interface system for the virtual reality applications.

  20. Dose calculation on voxels phantoms using the GEANT4 code

    International Nuclear Information System (INIS)

    Martins, Maximiano C.; Santos, Denison S.; Queiroz Filho, Pedro P.; Begalli, Marcia

    2009-01-01

    This work implemented an anthropomorphic phantom of voxels on the structure of Monte Carlo GEANT4, for utilization by professionals from the radioprotection, external dosimetry and medical physics. This phantom allows the source displacement that can be isotropic punctual, plain beam, linear or radioactive gas, in order to obtain diverse irradiation geometries. In them, the radioactive sources exposure is simulated viewing the determination of effective dose or the dose in each organ of the human body. The Zubal head and body trunk phantom was used, and we can differentiate the organs and tissues by the chemical constitution in soft tissue, lung tissue, bone tissue, water and air. The calculation method was validated through the comparison with other well established method, the Visual Monte Carlo (VMC). Besides, a comparison was done with the international recommendation for the evaluation of dose by exposure to punctual sources, described in the document TECDOC - 1162- Generic Procedures for Assessment and Response During a Radiological Emergency, where analytical expressions for this calculation are given. Considerations are made on the validity limits of these expressions for various irradiation geometries, including linear sources, immersion into clouds and contaminated soils

  1. Design construction and testing of a human abdomen phantom (anthropomorphic) for in-vivo dosimetry in radiology

    International Nuclear Information System (INIS)

    Addison, E.C.K.; Andam, A.B.; Nani, E.K.; Dogbe, R.

    2007-01-01

    Using direct measurement, we investigated entrance surface doses of patients for routine radiographs in attempt to develop evaluation methods of patient dose in order to establish the guidance level in Ghana. To date, patient doses have been evaluated by calculation based on radiographic conditions, or model experiments using phantoms, also based on several assumptions. Direct measurement of patient dose is difficult to perform in many patients due to its time requirement, level of expertise required and difficulty in providing an explanation of the procedure to the patient. However, such direct measurement is essential since it incorporates all aspects of radiography from the radiographic equipment used, to the actual conditions of each patient without assumption. In this study, we examined the need for introducing the guidance level, controversial points in the calculation method for patient dose evaluation, evaluation accuracy required for introducing the guidance level, and necessity for a standardized method. The variation between measured and calculated doses range between -4.8 to +29.3 per cent. Computational technique is a wide ranging and cost effective method od conducting representative patient dose estimations in plain radiography. (au)

  2. BrainK for Structural Image Processing: Creating Electrical Models of the Human Head

    Directory of Open Access Journals (Sweden)

    Kai Li

    2016-01-01

    Full Text Available BrainK is a set of automated procedures for characterizing the tissues of the human head from MRI, CT, and photogrammetry images. The tissue segmentation and cortical surface extraction support the primary goal of modeling the propagation of electrical currents through head tissues with a finite difference model (FDM or finite element model (FEM created from the BrainK geometries. The electrical head model is necessary for accurate source localization of dense array electroencephalographic (dEEG measures from head surface electrodes. It is also necessary for accurate targeting of cerebral structures with transcranial current injection from those surface electrodes. BrainK must achieve five major tasks: image segmentation, registration of the MRI, CT, and sensor photogrammetry images, cortical surface reconstruction, dipole tessellation of the cortical surface, and Talairach transformation. We describe the approach to each task, and we compare the accuracies for the key tasks of tissue segmentation and cortical surface extraction in relation to existing research tools (FreeSurfer, FSL, SPM, and BrainVisa. BrainK achieves good accuracy with minimal or no user intervention, it deals well with poor quality MR images and tissue abnormalities, and it provides improved computational efficiency over existing research packages.

  3. Multi-element determination in cancellous bone of human femoral head by PIXE

    International Nuclear Information System (INIS)

    Yuanxun Zhang; Yongping Zhang; Yongpeng Tong; Shijing Qiu; Xiaotao Wu; Kerong Dai

    1996-01-01

    Proton Induced X-ray Emission (PIXE) method is used for the determination of elemental concentrations in cancellous bone of human femoral head from five autopsies and seven patients with femoral neck broken. The specimen preparation and experimental procedure are described in detail. Using the t test, the results show that the concentrations of P, Ca, Fe, Cu, Sr in control group are higher than those in patient group, but the concentrations of S, K, Zn, Mn are not significantly different. The physiological functions of metallic elements in human bone are also discussed. (author). 19 refs., 1 fig., 4 tabs

  4. A Novel Instrumented Human Head Surrogate for the Impact Evaluation of Helmets

    Directory of Open Access Journals (Sweden)

    Nicola Petrone

    2018-02-01

    Full Text Available A novel Human Head Surrogate was obtained from available MRI scans of a 50th percentile male human head. Addictive manufacturing was used to produce the skull, the brain and the skin. All original MRI geometries were partially smoothed and adjusted to provide the best biofidelity compatible with printing and molding technology. The skull was 3D-printed in ABS and ten pressure sensors were placed into it. The brain surrogate was cast from silicon rubber in the 3D-printed plastic molds. Nine tri-axial accelerometers (placed at the tops of the lobes, at the sides of the lobes, in the cerebellum and in the center of mass and a three-axis gyroscope (at the center of mass were inserted into the silicon brain during casting. The cranium, after assembly with brain, was filled with silicon oil mimicking the cerebral fluid. Silicon rubber was cast in additional 3D-printed molds to form the skin surrounding the cranium. The skull base was adapted to be compatible with the Hybrid-III neck and allow the exit of brain sensors cabling. Preliminary experiments were carried out proving the functionality of the surrogate. Results showed how multiple accelerometers and pressure sensors allowed a better comprehension of the head complex motion during impacts.

  5. Heads of household programme in Argentina: a human rights-based policy?

    Science.gov (United States)

    Colina, Jorge; Giordano, Osvaldo; Torres, Alejandra; Cárdenas, Marcelo

    2009-01-01

    This study analyses the consultative councils (CC) of the Argentinian conditional cash transfer heads of household programme as an institutional innovation directed to put into practice some of the principles of the human rights' approach for eradicating poverty. Since the main responsibilities assigned to the CCs coincided with some of the main principles of the human rights' approach, the research is focused on how CCs responded in practice. Using a case study methodology we show that even when, in theory, the CCs incorporate some of the principles of the human rights' approach to the programme, they deviated from this purpose due to a persistent phenomenon in the social policy arena in developing countries: political clientelism. Policy recommendations are formulated in order to deal with clientelism in the framework of the human rights' approach.

  6. Thoraco-abdominal high-pitch dual-source CT angiography: Experimental evaluation of injection protocols with an anatomical human vascular phantom

    Energy Technology Data Exchange (ETDEWEB)

    Puippe, Gilbert D., E-mail: gilbert.puippe@usz.ch [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland); Winklehner, Anna [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland); Hasenclever, Peter; Plass, André [Division of Cardiac and Vascular Surgery, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland); Frauenfelder, Thomas; Baumueller, Stephan [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland)

    2012-10-15

    Objective: To experimentally evaluate three different contrast injection protocols at thoraco-abdominal high-pitch dual-source computed tomography angiography (CTA), with regard to level and homogeneity of vascular enhancement at different cardiac outputs. Materials and methods: A uniphasic, a biphasic as well as an individually tailored contrast protocol were tested using a human vascular phantom. Each protocol was scanned at 5 different cardiac outputs (3–5 L/min, steps of 0.5 L/min) using an extracorporeal cardiac pump. Vascular enhancement of the thoraco-abdominal aorta was measured every 5 cm. Overall mean enhancement of each protocol and mean enhancement for each cardiac output within each protocol were calculated. Enhancement homogeneity along the z-axis was evaluated for each cardiac output and protocol. Results: Overall mean enhancement was significantly higher in the uniphasic than in the other two protocols (all p < .05), whereas the difference between the biphasic and tailored protocol was not significant (p = .76). Mean enhancement among each of the 5 cardiac outputs within each protocol was significantly different (all p < .05). Only within the tailored protocol mean enhancement differed not significantly at cardiac outputs of 3.5 L/min vs. 5 L/min (484 ± 25 HU vs. 476 ± 19 HU, p = .14) and 4 vs. 5 L/min (443 ± 49 HU vs. 476 ± 19 HU, p = .05). Both, uniphasic and tailored protocol yielded homogenous enhancement at all cardiac outputs, whereas the biphasic protocol failed to achieve homogenous enhancement. Conclusion: This phantom study suggests that diagnostic and homogenous enhancement at thoraco-abdominal high-pitch dual-source CTA is feasible with either a uniphasic or an individually tailored contrast protocol.

  7. Human Papilloma Virus Associated Squamous Cell Carcinoma of the Head and Neck

    Science.gov (United States)

    Ajila, Vidya; Shetty, Harish; Babu, Subhas; Shetty, Veena; Hegde, Shruthi

    2015-01-01

    Oral cancer is one of the commonest causes for mortality and morbidity with squamous cell carcinoma being the sixth most frequent malignant tumour worldwide. In addition to tobacco and alcohol, human papilloma virus (HPV) is associated with a proportion of head and neck cancers. As in cervical cancers, HPV types 16 and 18 are the cause of malignant transformation. HPV-positive cancers of head and neck have unique characteristics such as occurrence in a younger age group, distinct clinical and molecular features, and better prognosis as compared to HPV-negative carcinomas. They also possess the potential for prevention by using vaccination. The present review describes in detail the salient features of HPV associated oral squamous cell carcinoma (OSCC), its differences from HPV-negative OSCC, diagnostic features, and recent strategies in prevention and management. PMID:26483987

  8. Human Papilloma Virus Associated Squamous Cell Carcinoma of the Head and Neck.

    Science.gov (United States)

    Ajila, Vidya; Shetty, Harish; Babu, Subhas; Shetty, Veena; Hegde, Shruthi

    2015-01-01

    Oral cancer is one of the commonest causes for mortality and morbidity with squamous cell carcinoma being the sixth most frequent malignant tumour worldwide. In addition to tobacco and alcohol, human papilloma virus (HPV) is associated with a proportion of head and neck cancers. As in cervical cancers, HPV types 16 and 18 are the cause of malignant transformation. HPV-positive cancers of head and neck have unique characteristics such as occurrence in a younger age group, distinct clinical and molecular features, and better prognosis as compared to HPV-negative carcinomas. They also possess the potential for prevention by using vaccination. The present review describes in detail the salient features of HPV associated oral squamous cell carcinoma (OSCC), its differences from HPV-negative OSCC, diagnostic features, and recent strategies in prevention and management.

  9. ICRU activity in the field of phantoms in diagnostic radiology

    International Nuclear Information System (INIS)

    Wambersie, A.

    1992-01-01

    The ICRU Report on 'Phantoms and Computational Models in Radiation Therapy, Diagnosis and Protection' is presented. Different types of phantoms may be defined. They may be broadly categorized according to their primary function: dosimetry, calibration and imaging. Within each functional category, there are 3 types or designs of phantoms: body phantoms (anthropomorphic), standard phantoms and reference phantoms (used in the definition and specification of certain radiation quantities). In radiological imaging, anthropomorphic body phantoms are used for measuring the absorbed dose distribution resulting from imaging procedures. Standard phantoms have simple reproducible geometry and are used for comparing measurements under standard conditions of exposure. Imaging phantoms are useful for evaluating a given imaging system; they contain different types of test pieces. The report contains a major section on human anatomy, from fetus to adult with the variations due to ethnic origin. Tolerance levels for the phantoms (composition, dimensions) are proposed and quality assurance programs are outlined. The report contains extensive appendices; human anatomical data and full specification of over 80 phantoms and computational models. ICRU Report 46 on 'Photon, electron, proton and neutron interaction data for body tissues' is closely related to the field of phantoms. It is a logical continuation on ICRU Report 44 (1989) on 'Tissue substitutes in radiation dosimetry and measurements' and contains the interaction data for more than 100 tissues, from fetal to adult, including some diseased tissues

  10. The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. Pt. 4

    International Nuclear Information System (INIS)

    Williams, G.; Zankl, M.; Drexler, G.

    1984-12-01

    This report considers the contribution from scattered radiation to the dose to organs and tissues which lie outside the useful therapy beams. The results presented are the product of Monte Carlo studies used to determine the tissue doses due to internal scattering of the useful beams only. General cases are calculated in which central target volumes in the trunk are treated with 10 x 14 cm 2 and 14 x 14 cm 2 fields from 200 kV, Co-60, 8 MV and 25 MV therapy equipment. Target volumes in the neck are considered to be treated with 5 x 5 cm 2 fields. Different treatment plans are calculated including rotational therapy. Also two specific cases are more fully analysed, namely for Ankylosing Spondylitis and central abdomen malignant disease in the region of the head of the pancreas. The calculated organ doses are presented in tables as a percentage of the target volume dose. (orig.)

  11. Web-based visualisation of head pose and facial expressions changes: monitoring human activity using depth data

    OpenAIRE

    Kalliatakis, Grigorios; Vidakis, Nikolaos; Triantafyllidis, Georgios

    2017-01-01

    Despite significant recent advances in the field of head pose estimation and facial expression recognition, raising the cognitive level when analysing human activity presents serious challenges to current concepts. Motivated by the need of generating comprehensible visual representations from different sets of data, we introduce a system capable of monitoring human activity through head pose and facial expression changes, utilising an affordable 3D sensing technology (Microsoft Kinect sensor)...

  12. Saturation measurement accuracy in clinical near-infrared cerebral oximeters with a 3D-printed channel array phantom

    Science.gov (United States)

    Afshari, Ali; Ghassemi, Pejhman; Halprin, Molly; Lin, Jonathan; Weininger, Sandy; Gandjbakhche, Amir H.; Wang, Jianting; Pfefer, Joshua

    2018-02-01

    Clinical cerebral oximeters based on near-infrared spectroscopy (NIRS) are a commonly used, non-invasive tool for intraoperative monitoring of hemoglobin saturation. Research to verify performance of cerebral oximeters in human subject trials has shown differences between commercially available devices. Test methods based on tissue-simulating phantoms have been proposed to augment clinical findings. While prior studies have focused on liquid phantoms, this work is aimed at developing methods based on solid polymer phantoms that are stable. Specifically, we have designed and fabricated a neonatal/pediatric head mimicking layered phantoms based on a 3D-printed cerebral matrix incorporating an array of vessel-simulating linear channels. Superficial layers incorporating homogeneous molded polydimethylsiloxane (PDMS) slabs were fabricated to represent CSF, scalp and skull regions. The cerebral matrix was filled with bovine blood desaturated with sodium dithionite to achieve oxygenation levels across the 40-90% range. Measurements were performed with a commercially available cerebral oximeter using two probes with different illumination-collection geometries, as designed for neonatal and pediatric patients. Reference measurements of samples were performed with a CO-oximeter before injection and after extraction. Results from applied cerebral oximeters indicate a strong sensitivity to the thickness of the superficial layer of the phantom. Better correlation with the reference CO-oximeter results were obtained in the superficial layer thickness of 0.8-2.5 mm range. Channel array phantoms with modular superficial layers represent a promising approach for performance testing of NIRS-based cerebral oximeters.

  13. Vertical eye position-dependence of the human vestibuloocular reflex during passive and active yaw head rotations.

    Science.gov (United States)

    Thurtell, M J; Black, R A; Halmagyi, G M; Curthoys, I S; Aw, S T

    1999-05-01

    Vertical eye position-dependence of the human vestibuloocular reflex during passive and active yaw head rotations. The effect of vertical eye-in-head position on the compensatory eye rotation response to passive and active high acceleration yaw head rotations was examined in eight normal human subjects. The stimuli consisted of brief, low amplitude (15-25 degrees ), high acceleration (4,000-6,000 degrees /s2) yaw head rotations with respect to the trunk (peak velocity was 150-350 degrees /s). Eye and head rotations were recorded in three-dimensional space using the magnetic search coil technique. The input-output kinematics of the three-dimensional vestibuloocular reflex (VOR) were assessed by finding the difference between the inverted eye velocity vector and the head velocity vector (both referenced to a head-fixed coordinate system) as a time series. During passive head impulses, the head and eye velocity axes aligned well with each other for the first 47 ms after the onset of the stimulus, regardless of vertical eye-in-head position. After the initial 47-ms period, the degree of alignment of the eye and head velocity axes was modulated by vertical eye-in-head position. When fixation was on a target 20 degrees up, the eye and head velocity axes remained well aligned with each other. However, when fixation was on targets at 0 and 20 degrees down, the eye velocity axis tilted forward relative to the head velocity axis. During active head impulses, the axis tilt became apparent within 5 ms of the onset of the stimulus. When fixation was on a target at 0 degrees, the velocity axes remained well aligned with each other. When fixation was on a target 20 degrees up, the eye velocity axis tilted backward, when fixation was on a target 20 degrees down, the eye velocity axis tilted forward. The findings show that the VOR compensates very well for head motion in the early part of the response to unpredictable high acceleration stimuli-the eye position- dependence of the

  14. Phantom cosmologies and fermions

    International Nuclear Information System (INIS)

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

    2008-01-01

    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. As an application we analyze the cosmological constant group for a fermionic seed fluid

  15. 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

  16. Field Distribution of Transcranial Static Magnetic Stimulation in Realistic Human Head Model.

    Science.gov (United States)

    Tharayil, Joseph J; Goetz, Stefan M; Bernabei, John M; Peterchev, Angel V

    2017-10-10

    The objective of this work was to characterize the magnetic field (B-field) that arises in a human brain model from the application of transcranial static magnetic field stimulation (tSMS). The spatial distribution of the B-field magnitude and gradient of a cylindrical, 5.08 cm × 2.54 cm NdFeB magnet were simulated in air and in a human head model using the finite element method and calibrated with measurements in air. The B-field was simulated for magnet placements over prefrontal, motor, sensory, and visual cortex targets. The impact of magnetic susceptibility of head tissues on the B-field was quantified. Peak B-field magnitude and gradient respectively ranged from 179-245 mT and from 13.3-19.0 T/m across the cortical targets. B-field magnitude, focality, and gradient decreased with magnet-cortex distance. The variation in B-field strength and gradient across the anatomical targets largely arose from the magnet-cortex distance. Head magnetic susceptibilities had negligible impact on the B-field characteristics. The half-maximum focality of the tSMS B-field ranged from 7-12 cm 3 . This is the first presentation and characterization of the three-dimensional (3D) spatial distribution of the B-field generated in a human brain model by tSMS. These data can provide quantitative dosing guidance for tSMS applications across various cortical targets and subjects. The finding that the B-field gradient is high near the magnet edges should be considered in studies where neural tissue is placed close to the magnet. The observation that susceptibility has negligible effects confirms assumptions in the literature. © 2017 International Neuromodulation Society.

  17. 3D printed phantoms mimicking cortical bone for the assessment of ultrashort echo time magnetic resonance imaging.

    Science.gov (United States)

    Rai, Robba; Manton, David; Jameson, Michael G; Josan, Sonal; Barton, Michael B; Holloway, Lois C; Liney, Gary P

    2018-02-01

    bone. The multicompartment anthropomorphic head phantom was successfully produced and able to simulate realistic air cavities, bony anatomy, and soft tissue. Image quality assessment in the tibia phantom using the PETRA sequence showed the suitability of the resin to mimic human anatomy with high SNR and contrast making it suitable for tissue segmentation. A solid resin material, which can be 3D printed, has been found to have similar magnetic resonance signal properties to human cortical bone. Phantoms replicating skeletal anatomy were successfully produced using this resin and demonstrated their use for image quality and segmentation assessment of ultrashort echo time sequences. © 2017 American Association of Physicists in Medicine.

  18. Primary Radiation Therapy for Head-and-Neck Cancer in the Setting of Human Immunodeficiency Virus

    International Nuclear Information System (INIS)

    Klein, Emily A.; Guiou, Michael; Farwell, D. Gregory; Luu, Quang; Lau, Derick H.; Stuart, Kerri; Vaughan, Andrew; Vijayakumar, Srinivasan; Chen, Allen M.

    2011-01-01

    Purpose: To analyze outcomes after radiation therapy for head-and-neck cancer among a cohort of patients with human immunodeficiency virus (HIV). Methods and Materials: The medical records of 12 patients with serologic evidence of HIV who subsequently underwent radiation therapy to a median dose of 68 Gy (range, 64-72 Gy) for newly diagnosed squamous cell carcinoma of the head and neck were reviewed. Six patients (50%) received concurrent chemotherapy. Intensity-modulated radiotherapy was used in 6 cases (50%). All patients had a Karnofsky performance status of 80 or 90. Nine patients (75%) were receiving antiretroviral therapies at the time of treatment, and the median CD4 count was 460 (range, 266-800). Toxicity was graded according to the Radiation Therapy Oncology Group / European Organization for the Treatment of Cancer toxicity criteria. Results: The 3-year estimates of overall survival and local-regional control were 78% and 92%, respectively. Acute Grade 3+ toxicity occurred in 7 patients (58%), the most common being confluent mucositis (5 patients) and moist skin desquamation (4 patients). Two patients experienced greater than 10% weight loss, and none experienced more than 15% weight loss from baseline. Five patients (42%) experienced treatment breaks in excess of 10 cumulative days, although none required hospitalization. There were no treatment-related fatalities. Conclusions: Radiation therapy for head-and-neck cancer seems to be relatively well tolerated among appropriately selected patients with HIV. The observed rates of toxicity were comparable to historical controls without HIV.

  19. Diagnostics of femoral head status in humans using laser spectroscopy - In vitro studies.

    Science.gov (United States)

    Lin, Huiying; Li, Wansha; Zhang, Hao; Chen, Peng; Chen, Delong; He, Wei; Svanberg, Sune; Svanberg, Katarina

    2017-10-01

    Osteonecrosis of the femoral head (ONFH), a recalcitrant and disabling disease, is caused by inadequate or fully disrupted blood supply to the affected segment of the subchondral bone. Theoretically, there will develop gas-filled pores during the bone decay process due to lacking blood supply. Unfortunately, the relationship between the gas-filled pores and ONFH is still unclear. Here, we have introduced diode laser absorption spectroscopy to detect oxygen and water vapor signals in the femoral heads from hip replacement in 19 patients. Five samples are affected by osteoarthritis (OA) and the others are related to ONFH. Oxygen and water vapor signals could be obtained, demonstrating the presence of gas-filled pores in both the OA and ONFH groups while the measurement results showed no significant difference. A study of gas exchange was also performed on one excised bone sample to study how these gas pores communicate with the ambient air. The results suggested that the obtained oxygen signals inside the bone samples originate from the invasion of ambient air, which is not expected in vivo. In conclusion, the ability to detect the gas signal of laser absorption spectroscopy shows the potential for the medical application of assessing the human femoral head in vivo. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A Novel Method for Intraoral Access to the Superior Head of the Human Lateral Pterygoid Muscle

    Directory of Open Access Journals (Sweden)

    Aleli Tôrres Oliveira

    2014-01-01

    Full Text Available Background. The uncoordinated activity of the superior and inferior parts of the lateral pterygoid muscle (LPM has been suggested to be one of the causes of temporomandibular joint (TMJ disc displacement. A therapy for this muscle disorder is the injection of botulinum toxin (BTX, of the LPM. However, there is a potential risk of side effects with the injection guide methods currently available. In addition, they do not permit appropriate differentiation between the two bellies of the muscle. Herein, a novel method is presented to provide intraoral access to the superior head of the human LPM with maximal control and minimal hazards. Methods. Computational tomography along with digital imaging software programs and rapid prototyping techniques were used to create a rapid prototyped guide to orient BTX injections in the superior LPM. Results. The method proved to be feasible and reliable. Furthermore, when tested in one volunteer it allowed precise access to the upper head of LPM, without producing side effects. Conclusions. The prototyped guide presented in this paper is a novel tool that provides intraoral access to the superior head of the LPM. Further studies will be necessary to test the efficacy and validate this method in a larger cohort of subjects.

  1. Radio frequency-induced temperature elevations in the human head considering small anatomical structures

    International Nuclear Information System (INIS)

    Schmid, G.; Ueberbacher, R.; Samaras, T.

    2007-01-01

    In order to enable a detailed numerical radio frequency (RF) dosimetry and the computations of RF-induced temperature elevations, high-resolution (0.1 mm) numerical models of the human eye, the inner ear organs and the pineal gland were developed and inserted into a commercially available head model. As radiation sources, generic models of handsets at 400, 900 and 1850 MHz operating in close proximity to the head were considered. The results, obtained by finite-difference time domain-based computations, showed a highly heterogeneous specific absorption rate (SAR) distribution and SAR-peaks inside the inner ear structures; however, the corresponding RF-induced temperature elevations were well below 0.1 deg. C, when considering typical output power values of hand-held devices. In case of frontal exposure, with the radiation sources ∼2.5 cm in front of the closed eye, maximum temperature elevations in the eye in the range of ∼0.2-0.6 deg. C were found for typical device output powers. A reduction in tissue perfusion mainly affected the maximum RF-induced temperature elevation of tissues deep inside the head. Similarly, worst-case considerations regarding pulsed irradiation affected temperature elevations in deep tissue significantly more than in superficial tissues. (authors)

  2. Integration of visual and non-visual self-motion cues during voluntary head movements in the human brain.

    Science.gov (United States)

    Schindler, Andreas; Bartels, Andreas

    2018-05-15

    Our phenomenological experience of the stable world is maintained by continuous integration of visual self-motion with extra-retinal signals. However, due to conventional constraints of fMRI acquisition in humans, neural responses to visuo-vestibular integration have only been studied using artificial stimuli, in the absence of voluntary head-motion. We here circumvented these limitations and let participants to move their heads during scanning. The slow dynamics of the BOLD signal allowed us to acquire neural signal related to head motion after the observer's head was stabilized by inflatable aircushions. Visual stimuli were presented on head-fixed display goggles and updated in real time as a function of head-motion that was tracked using an external camera. Two conditions simulated forward translation of the participant. During physical head rotation, the congruent condition simulated a stable world, whereas the incongruent condition added arbitrary lateral motion. Importantly, both conditions were precisely matched in visual properties and head-rotation. By comparing congruent with incongruent conditions we found evidence consistent with the multi-modal integration of visual cues with head motion into a coherent "stable world" percept in the parietal operculum and in an anterior part of parieto-insular cortex (aPIC). In the visual motion network, human regions MST, a dorsal part of VIP, the cingulate sulcus visual area (CSv) and a region in precuneus (Pc) showed differential responses to the same contrast. The results demonstrate for the first time neural multimodal interactions between precisely matched congruent versus incongruent visual and non-visual cues during physical head-movement in the human brain. The methodological approach opens the path to a new class of fMRI studies with unprecedented temporal and spatial control over visuo-vestibular stimulation. Copyright © 2018 Elsevier Inc. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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

  4. Design, fabrication and evaluation of a new calibration phantom for in vivo measurement of bone-seeking radionuclides (invited paper)

    International Nuclear Information System (INIS)

    Spitz, H.B.; Lodwick, J.

    2000-01-01

    A new anthropometric phantom has been developed for use in calibrating in vivo measurements of bone-seeking radionuclides. The phantom has the external shape and appearance of the human adult knee and contains a realistic femur, patella, tibia, and fibula. Unique formulations of polyurethanes, CaCo 3 , and other trace materials are used in construction of the phantom to produce substitutes for human tissue having the same density, attenuation coefficient, and effective Z as that of human muscle and trabecular bone. The formulation for trabecular bone includes provision for a precisely known quantity of radioactive material that is either uniformly distributed throughout the bone matrix or deposited on the exterior surface. The knee phantom is assembled in three interlocking sections that simplify inserting the skeletal structures and prevent streaming. One or more detectors can easily be positioned on the top or sides of the phantom. Intercomparison measurements of 241 Am in bone using separate arrays of phoswich and germanium detectors demonstrate that a single knee phantom exhibits the same detection efficiency as that using the skull. In vivo measurement of the knee is a desirable alternative to the head if facial contamination is present or when evaluating recent exposure to bone seeking radionuclides, since bones of the knee exhibit more rapid uptake than the skull. In practice, greater measurement efficiency can be obtained by placing detectors over both knees since a larger fraction of the total body activity is observed. Calibration measurements using the new anthropometric knee phantom demonstrate that it is durable, easy to use, and provides consistent results over repeated measurements. (author)

  5. Effectiveness of isopropyl myristate/cyclomethicone D5 solution of removing cuticular hydrocarbons from human head lice (Pediculus humanus capitis

    Directory of Open Access Journals (Sweden)

    Barnett Eric

    2012-09-01

    Full Text Available Abstract Background In the treatment of human head lice infestation, healthcare providers are increasingly concerned about lice becoming resistant to existing pesticide treatments. Traditional pesticides, used to control these pests, have a neurological mechanism of action. This publication describes a topical solution with a non-traditional mechanism of action, based on physical disruption of the wax layer that covers the cuticle of the louse exoskeleton. This topical solution has been shown clinically to cure 82% of patients with only a 10-minute treatment time, repeated once after 7 days. All insects, including human head lice, have a wax-covered exoskeleton. This wax, composed of hydrocarbons, provides the insect with protection against water loss and is therefore critical to its survival. When the protective wax is disrupted, water loss becomes uncontrollable and irreversible, leading to dehydration and death. A specific pattern of hydrocarbons has been found in all of the head louse cuticular wax studied. Iso-octane effectively removes these hydrocarbons from human head lice’s cuticular wax. Methods A method of head louse cuticle wax extraction and analysis by gas chromatography was developed. Human head lice (Pediculus humanus capitis were collected from infested patients and subjected to any of three extraction solvents comprising either the test product or one of two solvents introduced as controls. A gas chromatograph equipped with a flame ionization detector (GC/FID was used to determine the presence of hydrocarbons in the three head lice extracts. Results In the study reported herein, the test product isopropyl myristate/cyclomethicone D5 (IPM/D5 was shown to perform comparably with iso-octane, effectively extracting the target hydrocarbons from the cuticular wax that coats the human head louse exoskeleton. Conclusions Disruption of the integrity of the insect cuticle by removal of specific hydrocarbons found in the cuticular wax

  6. The level of detail required in a deformable phantom to accurately perform quality assurance of deformable image registration

    Science.gov (United States)

    Saenz, Daniel L.; Kim, Hojin; Chen, Josephine; Stathakis, Sotirios; Kirby, Neil

    2016-09-01

    The primary purpose of the study was to determine how detailed deformable image registration (DIR) phantoms need to adequately simulate human anatomy and accurately assess the quality of DIR algorithms. In particular, how many distinct tissues are required in a phantom to simulate complex human anatomy? Pelvis and head-and-neck patient CT images were used for this study as virtual phantoms. Two data sets from each site were analyzed. The virtual phantoms were warped to create two pairs consisting of undeformed and deformed images. Otsu’s method was employed to create additional segmented image pairs of n distinct soft tissue CT number ranges (fat, muscle, etc). A realistic noise image was added to each image. Deformations were applied in MIM Software (MIM) and Velocity deformable multi-pass (DMP) and compared with the known warping. Images with more simulated tissue levels exhibit more contrast, enabling more accurate results. Deformation error (magnitude of the vector difference between known and predicted deformation) was used as a metric to evaluate how many CT number gray levels are needed for a phantom to serve as a realistic patient proxy. Stabilization of the mean deformation error was reached by three soft tissue levels for Velocity DMP and MIM, though MIM exhibited a persisting difference in accuracy between the discrete images and the unprocessed image pair. A minimum detail of three levels allows a realistic patient proxy for use with Velocity and MIM deformation algorithms.

  7. Visualization of light propagation in visible Chinese human head for functional near-infrared spectroscopy

    Science.gov (United States)

    Li, Ting; Gong, Hui; Luo, Qingming

    2011-04-01

    Using the visible Chinese human data set, which faithfully represents human anatomy, we visualize the light propagation in the head in detail based on Monte Carlo simulation. The simulation is verified to agree with published experimental results in terms of a differential path-length factor. The spatial sensitivity profile turns out to seem like a fat tropical fish with strong distortion along the folding cerebral surface. The sensitive brain region covers the gray matter and extends to the superficial white matter, leading to a large penetration depth (>3 cm). Finally, the optimal source-detector separation is suggested to be narrowed down to 3-3.5 cm, while the sensitivity of the detected signal to brain activation reaches the peak of 8%. These results indicate that the cerebral cortex folding geometry actually has substantial effects on light propagation, which should be necessarily considered for applications of functional near-infrared spectroscopy.

  8. A micro-architectural evaluation of osteoporotic human femoral heads to guide implant placement in proximal femoral fractures.

    Science.gov (United States)

    Jenkins, Paul J; Ramaesh, Rishikesan; Pankaj, Pankaj; Patton, James T; Howie, Colin R; Goffin, Jérôme M; Merwe, Andrew van der; Wallace, Robert J; Porter, Daniel E; Simpson, A Hamish

    2013-10-01

    The micro-architecture of bone has been increasingly recognized as an important determinant of bone strength. Successful operative stabilization of fractures depends on bone strength. We evaluated the osseous micro-architecture and strength of the osteoporotic human femoral head. 6 femoral heads, obtained during arthroplasty surgery for femoral neck fracture, underwent micro-computed tomography (microCT) scanning at 30 μm, and bone volume ratio (BV/TV), trabecular thickness, structural model index, connection density, and degree of anisotropy for volumes of interest throughout the head were derived. A further 15 femoral heads underwent mechanical testing of compressive failure stress of cubes of trabecular bone from different regions of the head. The greatest density and trabecular thickness was found in the central core that extended from the medial calcar to the physeal scar. This region also correlated with the greatest degree of anisotropy and proportion of plate-like trabeculae. In the epiphyseal region, the trabeculae were organized radially from the physeal scar. The weakest area was found at the apex and peripheral areas of the head. The strongest region was at the center of the head. The center of the femoral head contained the strongest trabecular bone, with the thickest, most dense trabeculae. The apical region was weaker. From an anatomical and mechanical point of view, implants that achieve fixation in or below this central core may achieve the most stable fixation during fracture healing.

  9. Phantoms for IMRT dose distribution measurement and treatment verification

    International Nuclear Information System (INIS)

    Low, Daniel A.; Gerber, Russell L.; Mutic, Sasa; Purdy, James A.

    1998-01-01

    Background: The verification of intensity-modulated radiation therapy (IMRT) patient treatment dose distributions is currently based on custom-built or modified dose measurement phantoms. The only commercially available IMRT treatment planning and delivery system (Peacock, NOMOS Corp.) is supplied with a film phantom that allows accurate spatial localization of the dose distribution using radiographic film. However, measurements using other dosimeters are necessary for the thorough verification of IMRT. Methods: We have developed a phantom to enable dose measurements using a cylindrical ionization chamber and the localization of prescription isodose curves using a matrix of thermoluminescent dosimetry (TLD) chips. The external phantom cross-section is identical to that of the commercial phantom, to allow direct comparisons of measurements. A supplementary phantom has been fabricated to verify the IMRT dose distributions for pelvis treatments. Results: To date, this phantom has been used for the verification of IMRT dose distributions for head and neck and prostate cancer treatments. Designs are also presented for a phantom insert to be used with polymerizing gels (e.g., BANG-2) to obtain volumetric dose distribution measurements. Conclusion: The phantoms have proven useful in the quantitative evaluation of IMRT treatments

  10. Usefulness of a functional tracheobronchial phantom for interventional procedure

    International Nuclear Information System (INIS)

    Kim, Tae Hyung; Lim, Cheong Hwan; Kim, Jeong Koo

    2003-01-01

    To evaluate usefulness of a functional tracheobronchial phantom for interventional procedure. The functional phantom was made as a actual size with human normal anatomy used silicone and a paper clay mold. A tracheobronchial-shape clay mold was placed inside a square box and liquid silicone was poured. After the silicone was formed, the clay was removed. We measured film density and tracheobronchial angle at the human, animal and phantom respectively. The film density of trachea part were 0.76 (± 0.011) in human, 0.97 (± 0.015) in animal, 0.45 (± 0.016) in phantom. The tracheobronchial bifurcation part measured 0.51 (± 0.006) in human, 0.65 (± 0.005) in animal, 0.65 (± 0.008) in phantom. The right bronchus part measured 0.14 (± 0.008) in human, 0.59 (± 0.014) in animal and 0.04 (± 0.007) in phantom. The left bronchus were 0.54 (± 0.004) in human, 0.54 (± 0.008) in animal and 0.08 (± 0.008) in phantom. At the stent part were 0.54 (± 0.004) in human, 0.59 (± 0.011) in animal and 0.04 (± 0.007) in phantom, respectively. The tracheobronchial angle of the left bronchus site were 42.6 (± 2.07).deg. in human, 43.4 (± 2.40).deg. in animal and 35 (± 2.00).deg. in phantom, respectively. The right bronchus site were 32.8 (± 2.77).deg. in human, 34.6 (± 1.94).deg. in animal and 50.2 (± 1.30).deg. in phantom, respectively. The phantom was useful for in-vitro testing of tracheobronchial interventional procedure, since it was easy to reproduce

  11. Dosimetric characterization of model Cs-1 Rev2 cesium-131 brachytherapy source in water phantoms and human tissues with MCNP5 Monte Carlo simulation

    International Nuclear Information System (INIS)

    Wang Jianhua; Zhang Hualin

    2008-01-01

    A recently developed alternative brachytherapy seed, Cs-1 Rev2 cesium-131, has begun to be used in clinical practice. The dosimetric characteristics of this source in various media, particularly in human tissues, have not been fully evaluated. The aim of this study was to calculate the dosimetric parameters for the Cs-1 Rev2 cesium-131 seed following the recommendations of the AAPM TG-43U1 report [Rivard et al., Med. Phys. 31, 633-674 (2004)] for new sources in brachytherapy applications. Dose rate constants, radial dose functions, and anisotropy functions of the source in water, Virtual Water, and relevant human soft tissues were calculated using MCNP5 Monte Carlo simulations following the TG-43U1 formalism. The results yielded dose rate constants of 1.048, 1.024, 1.041, and 1.044 cGy h -1 U -1 in water, Virtual Water, muscle, and prostate tissue, respectively. The conversion factor for this new source between water and Virtual Water was 1.02, between muscle and water was 1.006, and between prostate and water was 1.004. The authors' calculation of anisotropy functions in a Virtual Water phantom agreed closely with Murphy's measurements [Murphy et al., Med. Phys. 31, 1529-1538 (2004)]. Our calculations of the radial dose function in water and Virtual Water have good agreement with those in previous experimental and Monte Carlo studies. The TG-43U1 parameters for clinical applications in water, muscle, and prostate tissue are presented in this work

  12. Clinical and scientific impact of human papillomavirus on head and neck cancer.

    Science.gov (United States)

    Friedman, Jeffrey M; Stavas, Mark J; Cmelak, Anthony J

    2014-10-10

    Head and neck cancer (HNC) arises from the skull base to the clavicles and is the fifth most common cancer in the world by incidence. Historically, in the developed world HNC was associated with tobacco use and alcohol consumption, and the combination of the two produced a synergistic increase in risk. However, beginning in 1983, investigators have found a significant and growing proportion of HNC patients with human papillomavirus-positive (HPV) tumors who neither drank nor used tobacco. Since that time, there has been increased interest in the molecular biology of HPV-positive HNC. Multiple studies now show that HPV has shifted the epidemiological landscape and prognosis of head and neck squamous cell carcinoma (HNSCC). These studies provide strong evidence for improved survival outcomes in patients with HPV-positive HNSCC compared to those with HPV-negative HNSCC. In many reports, HPV status is the strongest predictor of locoregional control, disease specific survival and overall survival. In response to these findings, there has been significant interest in the best management of HPV-positive disease. Discussions within major cooperative groups consider new trials designed to maintain the current strong survival outcomes while reducing the long-term treatment-related toxicities. This review will highlight the epidemiological, clinical and molecular discoveries surrounding HPV-related HNSCC over the recent decades and we conclude by suggesting how these findings may guide future treatment approaches.

  13. Productivity Losses Associated with Head and Neck Cancer Using the Human Capital and Friction Cost Approaches.

    Science.gov (United States)

    Pearce, Alison M; Hanly, Paul; Timmons, Aileen; Walsh, Paul M; O'Neill, Ciaran; O'Sullivan, Eleanor; Gooberman-Hill, Rachael; Thomas, Audrey Alforque; Gallagher, Pamela; Sharp, Linda

    2015-08-01

    Previous studies suggest that productivity losses associated with head and neck cancer (HNC) are higher than in other cancers. These studies have only assessed a single aspect of productivity loss, such as temporary absenteeism or premature mortality, and have only used the Human Capital Approach (HCA). The Friction Cost Approach (FCA) is increasingly recommended, although has not previously been used to assess lost production from HNC. The aim of this study was to estimate the lost productivity associated with HNC due to different types of absenteeism and premature mortality, using both the HCA and FCA. Survey data on employment status were collected from 251 HNC survivors in Ireland and combined with population-level survival estimates and national wage data. The cost of temporary and permanent time off work, reduced working hours and premature mortality using both the HCA and FCA were calculated. Estimated total productivity losses per employed person of working age were EUR253,800 using HCA and EUR6800 using FCA. The main driver of HCA costs was premature mortality (38% of total) while for FCA it was temporary time off (73% of total). The productivity losses associated with head and neck cancer are substantial, and return to work assistance could form an important part of rehabilitation. Use of both the HCA and FCA approaches allowed different drivers of productivity losses to be identified, due to the different assumptions of the two methods. For future estimates of productivity losses, the use of both approaches may be pragmatic.

  14. Organ dose evaluation for CT scans based on in-phantom measurements

    International Nuclear Information System (INIS)

    Liu Haikuan; Zhuo Weihai; Chen Bo; Yi Yanling; Li Dehong

    2009-01-01

    Objective: To explore the organ doses and their distributions in different projections of CT scans. Methods: The CT values were measured and the linear absorption coefficients were derived for the main organs of the anthropomorphic phantom to compare with the normal values of human beings. The radiophotoluminescent glass dosimeters were set into various tissues or organs of the phantom for mimic measurements of the organ doses undergoing the head, chest, abdomen and pelvis CT scans, respectively. Results: The tissue equivalence of the phantom used in this study was good. The brain had the largest organ dose undergoing the head CT scan. The organ doses in thyroid, breast, lung and oesophagus were relatively large in performing the chest CT scan, while the liver, stomach, colon and lung had relatively hrge organ doses in abdomen CT practice. The doses in bone surface and colon exceeded by 50 mGy in a single pelvis CT scan. Conclusions: The organ doses and their distributions largely vary with different projections of CT scans. The organ doses of colon, bone marrow,gonads and bladder are fairly large in performing pelvis CT scan, which should be paid attention in the practice. (authors)

  15. The science of shrinking human heads: tribal warfare and revenge among the South American Jivaro-Shuar.

    Science.gov (United States)

    Jandial, Rahul; Hughes, Samuel A; Aryan, Henry E; Marshall, Lawrence F; Levy, Michael L

    2004-11-01

    THE PRACTICE OF "head-shrinking" has been the proper domain not of Africa but rather of the denizens of South America. Specifically, in the post-Columbian period, it has been most famously the practice of a tribe of indigenous people commonly called the Jivaro or Jivaro-Shuar. The evidence suggests that the Jivaro-Shuar are merely the last group to retain a custom widespread in northwestern South America. In both ceramic and textile art of the pre-Columbian residents of Peru, the motif of trophy heads smaller than normal life-size heads commonly recurs; the motif is seen even in surviving carvings in stone and shell. Moreover, although not true shrunken heads, trophy heads found in late pre-Columbian and even post-Columbian graves of the region demonstrate techniques of display very similar to those used by the Jivaro-Shuar, at least some of which are best understood in the context of head-shrinking. Regardless, the Jivaro-Shuar and their practices provide an illustrative counterexample to popular myth regarding the culture and science of the shrinking of human heads.

  16. A low-cost phantom for simple routine testing of single photon emission computed tomography (SPECT) cameras

    International Nuclear Information System (INIS)

    Ng, A.H.; Ng, K.H.; Dharmendra, H.; Perkins, A.C.

    2009-01-01

    A simple sphere test phantom has been developed for routine performance testing of SPECT systems in situations where expensive commercial phantoms may not be available. The phantom was based on a design with six universal syringe hubs set in the frame to support a circular array of six glass blown spheres of different sizes. The frame was then placed into a water-filled CT abdomen phantom and scanned with a triple head camera system (Philips IRIX TM , USA). Comparison was made with a commercially available phantom (Deluxe Jaszczak phantom). Whereas the commercial phantom demonstrates cold spot resolution, an important advantage of the sphere test phantom was that hot spot resolution could be easily measured using almost half (370 MBq) of the activity recommended for use in the commercial phantom. Results showed that the contrast increased non-linearly with sphere volume and radionuclide concentration. The phantom was found to be suitable as an inexpensive option for daily performance tests.

  17. Temperature elevation in the eye of anatomically based human head models for plane-wave exposures

    International Nuclear Information System (INIS)

    Hirata, A; Watanabe, S; Fujiwara, O; Kojima, M; Sasaki, K; Shiozawa, T

    2007-01-01

    This study investigated the temperature elevation in the eye of anatomically based human head models for plane-wave exposures. The finite-difference time-domain method is used for analyzing electromagnetic absorption and temperature elevation. The eyes in the anatomic models have average dimensions and weight. Computational results show that the ratio of maximum temperature in the lens to the eye-average SAR (named 'heating factor for the lens') is almost uniform (0.112-0.147 deg. C kg W -1 ) in the frequency region below 3 GHz. Above 3 GHz, this ratio increases gradually with an increase of frequency, which is attributed to the penetration depth of an electromagnetic wave. Particular attention is paid to the difference in the heating factor for the lens between this study and earlier works. Considering causes clarified in this study, compensated heating factors in all these studies are found to be in good agreement

  18. Brain response to primary blast wave using validated finite element models of human head and advanced combat helmet

    Directory of Open Access Journals (Sweden)

    Liying eZhang

    2013-08-01

    Full Text Available Blast-induced traumatic brain injury has emerged as a signature injury in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH, a finite element (FE study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27-0.66 MPa from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP in the head ranged from 0.68-1.8 MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10-35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44% was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%. The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence "iso-damage" curves for brain injury are likely different than the Bowen curves

  19. Development of Realistic Head Models for Electromagnetic Source Imaging of the Human Brain

    National Research Council Canada - National Science Library

    Akalin, Z

    2001-01-01

    In this work, a methodology is developed to solve the forward problem of electromagnetic source imaging using realistic head models, For this purpose, first segmentation of the 3 dimensional MR head...

  20. Survey of Permethrin and Malathion Resistance in Human Head Lice Populations from Denmark

    DEFF Research Database (Denmark)

    Kristensen, Michael; Knorr, Mette; Rasmussen, Anne-Marie

    2006-01-01

    was selected, 2 ng of permethrin and 100 ng of malathion per head louse, respectively. Head lice were collected from heads of infested children in Denmark at 33 primary schools, one kindergarten, and seven boarding schools. The lice were collected by combing of dry hair, with a fine-toothed antilouse comb...

  1. HEAVEN: The head anastomosis venture Project outline for the first human head transplantation with spinal linkage (GEMINI)

    OpenAIRE

    Canavero, Sergio

    2013-01-01

    In 1970, the first cephalosomatic linkage was achieved in the monkey. However, the technology did not exist for reconnecting the spinal cord, and this line of research was no longer pursued. In this paper, an outline for the first total cephalic exchange in man is provided and spinal reconnection is described. The use of fusogens, special membrane-fusion substances, is discussed in view of the first human cord linkage. Several human diseases without cure might benefit from the procedure.

  2. The influence of gravity on regional lung blood flow in humans: SPECT in the upright and head-down posture.

    Science.gov (United States)

    Ax, M; Sanchez-Crespo, A; Lindahl, S G E; Mure, M; Petersson, J

    2017-06-01

    Previous studies in humans have shown that gravity has little influence on the distribution of lung blood flow while changing posture from supine to prone. This study aimed to evaluate the maximal influence of posture by comparison of regional lung blood flow in the upright and head-down posture in 8 healthy volunteers, using a tilt table. Regional lung blood flow was marked by intravenous injection of macroaggregates of human albumin labeled with 99m Tc or 113m In, in the upright and head-down posture, respectively, during tidal breathing. Both radiotracers remain fixed in the lung after administration. The distribution of radioactivity was mapped using quantitative single photon emission computed tomography (SPECT) corrected for attenuation and scatter. All images were obtained supine during tidal breathing. A shift from upright to the head-down posture caused a clear redistribution of blood flow from basal to apical regions. We conclude that posture plays a role for the distribution of lung blood flow in upright humans, and that the influence of posture, and thereby gravity, is much greater in the upright and head-down posture than in horizontal postures. However, the results of the study demonstrate that lung structure is the main determinant of regional blood flow and gravity is a secondary contributor to the distribution of lung blood flow in the upright and head-down positions. NEW & NOTEWORTHY Using a dual-isotope quantitative SPECT method, we demonstrated that although a shift in posture redistributes blood flow in the direction of gravity, the results are also consistent with lung structure being a greater determinant of regional blood flow than gravity. To our knowledge, this is the first study to use modern imaging methods to quantify the shift in regional lung blood flow in humans at a change between the upright and head-down postures. Copyright © 2017 the American Physiological Society.

  3. Thermal effects of dorsal head immersion in cold water on nonshivering humans.

    Science.gov (United States)

    Giesbrecht, Gordon G; Lockhart, Tamara L; Bristow, Gerald K; Steinman, Allan M

    2005-11-01

    Personal floatation devices maintain either a semirecumbent flotation posture with the head and upper chest out of the water or a horizontal flotation posture with the dorsal head and whole body immersed. The contribution of dorsal head and upper chest immersion to core cooling in cold water was isolated when the confounding effect of shivering heat production was inhibited with meperidine (Demerol, 2.5 mg/kg). Six male volunteers were immersed four times for up to 60 min, or until esophageal temperature = 34 degrees C. An insulated hoodless dry suit or two different personal floatation devices were used to create four conditions: 1) body insulated, head out; 2) body insulated, dorsal head immersed; 3) body exposed, head (and upper chest) out; and 4) body exposed, dorsal head (and upper chest) immersed. When the body was insulated, dorsal head immersion did not affect core cooling rate (1.1 degrees C/h) compared with head-out conditions (0.7 degrees C/h). When the body was exposed, however, the rate of core cooling increased by 40% from 3.6 degrees C/h with the head out to 5.0 degrees C/h with the dorsal head and upper chest immersed (P immersed (approximately 10%). The exaggerated core cooling during dorsal head immersion (40% increase) may result from the extra heat loss affecting a smaller thermal core due to intense thermal stimulation of the body and head and resultant peripheral vasoconstriction. Dorsal head and upper chest immersion in cold water increases the rate of core cooling and decreases potential survival time.

  4. BabyMEG: A whole-head pediatric magnetoencephalography system for human brain development research

    Science.gov (United States)

    Okada, Yoshio; Hämäläinen, Matti; Pratt, Kevin; Mascarenas, Anthony; Miller, Paul; Han, Menglai; Robles, Jose; Cavallini, Anders; Power, Bill; Sieng, Kosal; Sun, Limin; Lew, Seok; Doshi, Chiran; Ahtam, Banu; Dinh, Christoph; Esch, Lorenz; Grant, Ellen; Nummenmaa, Aapo; Paulson, Douglas

    2016-09-01

    We developed a 375-channel, whole-head magnetoencephalography (MEG) system ("BabyMEG") for studying the electrophysiological development of human brain during the first years of life. The helmet accommodates heads up to 95% of 36-month old boys in the USA. The unique two-layer sensor array consists of: (1) 270 magnetometers (10 mm diameter, ˜15 mm coil-to-coil spacing) in the inner layer, (2) thirty-five three-axis magnetometers (20 mm × 20 mm) in the outer layer 4 cm away from the inner layer. Additionally, there are three three-axis reference magnetometers. With the help of a remotely operated position adjustment mechanism, the sensor array can be positioned to provide a uniform short spacing (mean 8.5 mm) between the sensor array and room temperature surface of the dewar. The sensors are connected to superconducting quantum interference devices (SQUIDs) operating at 4.2 K with median sensitivity levels of 7.5 fT/√Hz for the inner and 4 fT/√Hz for the outer layer sensors. SQUID outputs are digitized by a 24-bit acquisition system. A closed-cycle helium recycler provides maintenance-free continuous operation, eliminating the need for helium, with no interruption needed during MEG measurements. BabyMEG with the recycler has been fully operational from March, 2015. Ongoing spontaneous brain activity can be monitored in real time without interference from external magnetic noise sources including the recycler, using a combination of a lightly shielded two-layer magnetically shielded room, an external active shielding, a signal-space projection method, and a synthetic gradiometer approach. Evoked responses in the cortex can be clearly detected without averaging. These new design features and capabilities represent several advances in MEG, increasing the utility of this technique in basic neuroscience as well as in clinical research and patient studies.

  5. MIDA: A Multimodal Imaging-Based Detailed Anatomical Model of the Human Head and Neck.

    Directory of Open Access Journals (Sweden)

    Maria Ida Iacono

    Full Text Available Computational modeling and simulations are increasingly being used to complement experimental testing for analysis of safety and efficacy of medical devices. Multiple voxel- and surface-based whole- and partial-body models have been proposed in the literature, typically with spatial resolution in the range of 1-2 mm and with 10-50 different tissue types resolved. We have developed a multimodal imaging-based detailed anatomical model of the human head and neck, named "MIDA". The model was obtained by integrating three different magnetic resonance imaging (MRI modalities, the parameters of which were tailored to enhance the signals of specific tissues: i structural T1- and T2-weighted MRIs; a specific heavily T2-weighted MRI slab with high nerve contrast optimized to enhance the structures of the ear and eye; ii magnetic resonance angiography (MRA data to image the vasculature, and iii diffusion tensor imaging (DTI to obtain information on anisotropy and fiber orientation. The unique multimodal high-resolution approach allowed resolving 153 structures, including several distinct muscles, bones and skull layers, arteries and veins, nerves, as well as salivary glands. The model offers also a detailed characterization of eyes, ears, and deep brain structures. A special automatic atlas-based segmentation procedure was adopted to include a detailed map of the nuclei of the thalamus and midbrain into the head model. The suitability of the model to simulations involving different numerical methods, discretization approaches, as well as DTI-based tensorial electrical conductivity, was examined in a case-study, in which the electric field was generated by transcranial alternating current stimulation. The voxel- and the surface-based versions of the models are freely available to the scientific community.

  6. Canine spontaneous head and neck squamous cell carcinomas represent their human counterparts at the molecular level.

    Directory of Open Access Journals (Sweden)

    Deli Liu

    2015-06-01

    Full Text Available Spontaneous canine head and neck squamous cell carcinoma (HNSCC represents an excellent model of human HNSCC but is greatly understudied. To better understand and utilize this valuable resource, we performed a pilot study that represents its first genome-wide characterization by investigating 12 canine HNSCC cases, of which 9 are oral, via high density array comparative genomic hybridization and RNA-seq. The analyses reveal that these canine cancers recapitulate many molecular features of human HNSCC. These include analogous genomic copy number abnormality landscapes and sequence mutation patterns, recurrent alteration of known HNSCC genes and pathways (e.g., cell cycle, PI3K/AKT signaling, and comparably extensive heterogeneity. Amplification or overexpression of protein kinase genes, matrix metalloproteinase genes, and epithelial-mesenchymal transition genes TWIST1 and SNAI1 are also prominent in these canine tumors. This pilot study, along with a rapidly growing body of literature on canine cancer, reemphasizes the potential value of spontaneous canine cancers in HNSCC basic and translational research.

  7. Gene Expression Changes in Femoral Head Necrosis of Human Bone Tissue

    Directory of Open Access Journals (Sweden)

    Bernadett Balla

    2011-01-01

    Full Text Available Osteonecrosis of the femoral head (ONFH is the result of an interruption of the local circulation and the injury of vascular supply of bone. Multiple factors have been implicated in the development of the disease. However the mechanism of ischemia and necrosis in non-traumatic ONFH is not clear. The aim of our investigation was to identify genes that are differently expressed in ONFH vs. non-ONFH human bone and to describe the relationships between these genes using multivariate data analysis. Six bone tissue samples from ONFH male patients and 8 bone tissue samples from non-ONFH men were examined. The expression differences of selected 117 genes were analyzed by TaqMan probe-based quantitative real-time RT-PCR system. The significance test indicated marked differences in the expression of nine genes between ONFH and non-ONFH individuals. These altered genes code for collagen molecules, an extracellular matrix digesting metalloproteinase, a transcription factor, an adhesion molecule, and a growth factor. Canonical variates analysis demonstrated that ONFH and non-ONFH bone tissues can be distinguished by the multiple expression profile analysis of numerous genes controlled via canonical TGFB pathway as well as genes coding for extracellular matrix composing collagen type molecules. The markedly altered gene expression profile observed in the ONFH of human bone tissue may provide further insight into the pathogenetic process of osteonecrotic degeneration of bone.

  8. Tissue quantification for development of pediatric phantom

    International Nuclear Information System (INIS)

    Alves, A.F.F.; Miranda, J.R.A.; Pina, D.R.

    2013-01-01

    The optimization of the risk- benefit ratio is a major concern in the pediatric radiology, due to the greater vulnerability of children to the late somatic effects and genetic effects of exposure to radiation compared to adults. In Brazil, it is estimated that the causes of death from head trauma are 18 % for the age group between 1-5 years and the radiograph is the primary diagnostic test for the detection of skull fracture . Knowing that the image quality is essential to ensure the identification of structures anatomical and minimizing errors diagnostic interpretation, this paper proposed the development and construction of homogeneous phantoms skull, for the age group 1-5 years. The construction of the phantoms homogeneous was performed using the classification and quantification of tissue present in the skull of pediatric patients. In this procedure computational algorithms were used, using Matlab, to quantify distinct biological tissues present in the anatomical regions studied , using pictures retrospective CT scans. Preliminary data obtained from measurements show that between the ages of 1-5 years, assuming an average anteroposterior diameter of the pediatric skull region of the 145.73 ± 2.97 mm, can be represented by 92.34 mm ± 5.22 of lucite and 1.75 ± 0:21 mm of aluminum plates of a provision of PEP (Pacient equivalent phantom). After its construction, the phantoms will be used for image and dose optimization in pediatric protocols process to examinations of computerized radiography

  9. Conceiving Human Interaction by Visualising Depth Data of Head Pose Changes and Emotion Recognition via Facial Expressions

    NARCIS (Netherlands)

    Kalliatakis, Grigorios; Stergiou, A.G.; Vidakis, Nikolaos

    2017-01-01

    Affective computing in general and human activity and intention analysis in particular comprise a rapidly-growing field of research. Head pose and emotion changes present serious challenges when applied to player’s training and ludology experience in serious games, or analysis of customer

  10. Breast phantom for mammary tissue characterization by near infrared spectroscopy

    International Nuclear Information System (INIS)

    Miranda, D A; Cristiano, K L; Gutiérrez, J C

    2013-01-01

    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

  11. Effect of cell-phone radiofrequency on angiogenesis and cell invasion in human head and neck cancer cells.

    Science.gov (United States)

    Alahmad, Yaman M; Aljaber, Mohammed; Saleh, Alaaeldin I; Yalcin, Huseyin C; Aboulkassim, Tahar; Yasmeen, Amber; Batist, Gerald; Moustafa, Ala-Eddin Al

    2018-05-13

    Today, the cell phone is the most widespread technology globally. However, the outcome of cell-phone radiofrequency on head and neck cancer progression has not yet been explored. The chorioallantoic membrane (CAM) and human head and neck cancer cell lines, FaDu and SCC25, were used to explore the outcome of cell-phone radiofrequency on angiogenesis, cell invasion, and colony formation of head and neck cancer cells, respectively. Western blot analysis was used to investigate the impact of the cell phone on the regulation of E-cadherin and Erk1/Erk2 genes. Our data revealed that cell-phone radiofrequency promotes angiogenesis of the CAM. In addition, the cell phone enhances cell invasion and colony formation of human head and neck cancer cells; this is accompanied by a downregulation of E-cadherin expression. More significantly, we found that the cell phone can activate Erk1/Erk2 in our experimental models. Our investigation reveals that cell-phone radiofrequency could enhance head and neck cancer by stimulating angiogenesis and cell invasion via Erk1/Erk2 activation. © 2018 Wiley Periodicals, Inc.

  12. Influence of Manufacturing Processes on the Performance of Phantom Lungs

    International Nuclear Information System (INIS)

    Traub, Richard J.

    2008-01-01

    Chest counting is an important tool for estimating the radiation dose to individuals who have inhaled radioactive materials. Chest counting systems are calibrated by counting the activity in the lungs of phantoms where the activity in the phantom lungs is known. In the United States a commonly used calibration phantom was developed at the Lawrence Livermore National Laboratory and is referred to as the Livermore Torso Phantom. An important feature of this phantom is that the phantom lungs can be interchanged so that the counting system can be challenged by different combinations of radionuclides and activity. Phantom lungs are made from lung tissue substitutes whose constituents are foaming plastics and various adjuvants selected to make the lung tissue substitute similar to normal healthy lung tissue. Some of the properties of phantom lungs cannot be readily controlled by phantom lung manufacturers. Some, such as density, are a complex function of the manufacturing process, while others, such as elemental composition of the bulk plastic are controlled by the plastics manufacturer without input, or knowledge of the phantom manufacturer. Despite the fact that some of these items cannot be controlled, they can be measured and accounted for. This report describes how manufacturing processes can influence the performance of phantom lungs. It is proposed that a metric that describes the brightness of the lung be employed by the phantom lung manufacturer to determine how well the phantom lung approximates the characteristics of a human lung. For many purposes, the linear attenuation of the lung tissue substitute is an appropriate surrogate for the brightness

  13. 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....

  14. Phantom crash confirms models

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    To test computer models of how a nuclear reactor's containment building would fare if an airplane crashed into it, the Muto Institute in Tokyo sponsored a 3.2 million dollar project at Sandia National Laboratory to slam an F-4 Phantom jet into a 500 ton concrete wall. The results showed that the computer calculations were accurate

  15. Fabrication of subcutaneous veins phantom for vessel visualization system

    Science.gov (United States)

    Cheng, Kai; Narita, Kazuyuki; Morita, Yusuke; Nakamachi, Eiji; Honda, Norihiro; Awazu, Kunio

    2013-09-01

    The technique of subcutaneous veins imaging by using NIR (Near Infrared Radiation) is widely used in medical applications, such as the intravenous injection and the blood sampling. In the previous study, an automatic 3D blood vessel search and automatic blood sampling system was newly developed. In order to validate this NIR imaging system, we adopted the subcutaneous vein in the human arm and its artificial phantom, which imitate the human fat and blood vessel. The human skin and subcutaneous vein is characterized as the uncertainty object, which has the individual specificity, non-accurate depth information, non-steady state and hardly to be fixed in the examination apparatus. On the other hand, the conventional phantom was quite distinct from the human's characteristics, such as the non-multilayer structure, disagreement of optical property. In this study, we develop a multilayer phantom, which is quite similar with human skin, for improvement of NIR detection system evaluation. The phantom consists of three layers, such as the epidermis layer, the dermis layer and the subcutaneous fat layer. In subcutaneous fat layer, we built a blood vessel. We use the intralipid to imitate the optical scattering characteristics of human skin, and the hemoglobin and melanin for the optical absorption characteristics. In this study, we did two subjects. First, we decide the fabrication process of the phantom. Second, we compared newly developed phantoms with human skin by using our NIR detecting system, and confirm the availability of these phantoms.

  16. Analysis of SAR distribution in human head of antenna used in wireless power transform based on magnetic resonance.

    Science.gov (United States)

    Gong, Feixiang; Wei, Zhiqiang; Cong, Yanping; Chi, Haokun; Yin, Bo; Sun, Mingui

    2017-07-20

    In this paper, a novel wireless power transfer antenna system was designed for human head implantable devices. The antenna system used the structure of three plates and four coils and operated at low frequencies to transfer power via near field. In order to verify the electromagnetic radiation safety on the human head, the electromagnetic intensity and specific absorption rate (SAR) were studied by finite-difference-time-domain (FDTD) method. A three-layer model of human head including skin, bone and brain tissues was constructed. The transmitting and receiving antenna were set outside and inside the model. The local and average SAR were simulated at the resonance frequency of 18.67 MHz in two situations, in one scenario both transmitting and receiving coil worked, while in the other scenario only the transmitting coil worked. The results showed that the maximum of 10 g SAR average value of human thoracic were 0.142 W/kg and 0.148 W/kg, respectively, both were lower than the international safety standards for human body of the ICNIRP and FCC, which verified the safety of the human body in wireless power transmission based on magnetic coupling resonance.

  17. What's the risk? Identifying potential human pathogens within grey-headed flying foxes faeces.

    Directory of Open Access Journals (Sweden)

    Rebekah Henry

    Full Text Available Pteropus poliocephalus (grey-headed flying foxes are recognised vectors for a range of potentially fatal human pathogens. However, to date research has primarily focused on viral disease carriage, overlooking bacterial pathogens, which also represent a significant human disease risk. The current study applied 16S rRNA amplicon sequencing, community analysis and a multi-tiered database OTU picking approach to identify faecal-derived zoonotic bacteria within two colonies of P. poliocephalus from Victoria, Australia. Our data show that sequences associated with Enterobacteriaceae (62.8% ± 24.7%, Pasteurellaceae (19.9% ± 25.7% and Moraxellaceae (9.4% ± 11.8% dominate flying fox faeces. Further colony specific differences in bacterial faecal colonisation patterns were also identified. In total, 34 potential pathogens, representing 15 genera, were identified. However, species level definition was only possible for Clostridium perfringens, which likely represents a low infectious risk due to the low proportion observed within the faeces and high infectious dose required for transmission. In contrast, sequences associated with other pathogenic species clusters such as Haemophilus haemolyticus-H. influenzae and Salmonella bongori-S. enterica, were present at high proportions in the faeces, and due to their relatively low infectious doses and modes of transmissions, represent a greater potential human disease risk. These analyses of the microbial community composition of Pteropus poliocephalus have significantly advanced our understanding of the potential bacterial disease risk associated with flying foxes and should direct future epidemiological and quantitative microbial risk assessments to further define the health risks presented by these animals.

  18. How the unique configuration of the human head may enhance flavor perception capabilities: an evolutionary perspective

    Directory of Open Access Journals (Sweden)

    Daniel E Lieberman

    2014-07-01

    Full Text Available Since flavor derives from the synthesis of taste, somatosensation and smell, one of the most important factors in the ability to perceive flavor is retronasal olfaction in which volatile compounds pass from the oral cavity through the pharynx to the olfactory epithelium. Retronasal olfaction has been documented in both humans and rodents, but appears less effective in rodents than orthonasal olfaction because expired air does not come into as much contact with the sensory neurons in the olfactory epithelium as inspired air [1,2]. Detailed comparisons of retronasal airflow patterns among different species have not been conducted, but several lines of evidence lead to the hypothesis that retronasal airflow may be specially enhanced in humans because of four derived features of the human head and neck that evolved at different stages because of selection for functions other than olfaction [3]. If so, then human flavor perception capabilities may be more derived than is commonly appreciated, and perhaps played a role in selecting for the evolution of cooking. The first derived adaptation that aids human retronasal olfaction is the absence of the transverse lamina, a horizontal shelf of bone that partitions the olfactory chamber of the nasal fossa from the more inferior respiratory passage. This lamina, which is present in most mammals, was lost during the evolution of monkeys (haplorhines from more primitive primates (strepsirhines as part of a reorganization of the nasal cavity. The function of the transverse lamina has not been tested but it probably aids orthonasal olfaction by trapping inspired air in the olfactory region. Loss of the transverse lamina is commonly interpreted to be one of several trade-offs in primate evolution that favored vision over olfaction [4], but it likely benefits retronasal olfaction by permitting a direct pathway for expired air to flow towards the olfactory epithelium. A second derived adaptation present in humans is

  19. Homemade ultrasound phantom for simulation of hydronephrosis

    Directory of Open Access Journals (Sweden)

    Ana Karine Brandao Novaes

    2018-05-01

    Full Text Available Abstract In this article, we describe the development of a simple and inexpensive simulation phantom as a surrogate of human hydronephrosis for the identification of urinary tract obstruction at bedside to be used in undergraduate training of medical students.

  20. Highly preserved consensus gene modules in human papilloma virus 16 positive cervical cancer and head and neck cancers.

    Science.gov (United States)

    Zhang, Xianglan; Cha, In-Ho; Kim, Ki-Yeol

    2017-12-26

    In this study, we investigated the consensus gene modules in head and neck cancer (HNC) and cervical cancer (CC). We used a publicly available gene expression dataset, GSE6791, which included 42 HNC, 14 normal head and neck, 20 CC and 8 normal cervical tissue samples. To exclude bias because of different human papilloma virus (HPV) types, we analyzed HPV16-positive samples only. We identified 3824 genes common to HNC and CC samples. Among these, 977 genes showed high connectivity and were used to construct consensus modules. We demonstrated eight consensus gene modules for HNC and CC using the dissimilarity measure and average linkage hierarchical clustering methods. These consensus modules included genes with significant biological functions, including ATP binding and extracellular exosome. Eigengen network analysis revealed the consensus modules were highly preserved with high connectivity. These findings demonstrate that HPV16-positive head and neck and cervical cancers share highly preserved consensus gene modules with common potentially therapeutic targets.

  1. 'Goats that stare at men': dwarf goats alter their behaviour in response to human head orientation, but do not spontaneously use head direction as a cue in a food-related context.

    Science.gov (United States)

    Nawroth, Christian; von Borell, Eberhard; Langbein, Jan

    2015-01-01

    Recently, comparative research on the mechanisms and species-specific adaptive values of attributing attentive states and using communicative cues has gained increased interest, particularly in non-human primates, birds, and dogs. Here, we investigate these phenomena in a farm animal species, the dwarf goat (Capra aegagrus hircus). In the first experiment, we investigated the effects of different human head and body orientations, as well as human experimenter presence/absence, on the behaviour of goats in a food-anticipating paradigm. Over a 30-s interval, the experimenter engaged in one of four different postures or behaviours (head and body towards the subject-'Control', head to the side, head and body away from the subject, or leaving the room) before delivering a reward. We found that the level of subjects' active anticipatory behaviour was highest in the control condition and decreased with a decreasing level of attention paid to the subject by the experimenter. Additionally, goats 'stared' (i.e. stood alert) at the experimental set-up for significantly more time when the experimenter was present but paid less attention to the subject ('Head' and 'Back' condition) than in the 'Control' and 'Out' conditions. In a second experiment, the experimenter provided different human-given cues that indicated the location of a hidden food reward in a two-way object choice task. Goats were able to use both 'Touch' and 'Point' cues to infer the correct location of the reward but did not perform above the level expected by chance in the 'Head only' condition. We conclude that goats are able to differentiate among different body postures of a human, including head orientation; however, despite their success at using multiple physical human cues, they fail to spontaneously use human head direction as a cue in a food-related context.

  2. Toward the holistic, reference, and extendable atlas of the human brain, head, and neck.

    Science.gov (United States)

    Nowinski, Wieslaw L

    2015-06-01

    Despite numerous efforts, a fairly complete (holistic) anatomical model of the whole, normal, adult human brain, which is required as the reference in brain studies and clinical applications, has not yet been constructed. Our ultimate objective is to build this kind of atlas from advanced in vivo imaging. This work presents the taxonomy of our currently developed brain atlases and addresses the design, content, functionality, and current results in the holistic atlas development as well as atlas usefulness and future directions. We have developed to date 35 commercial brain atlases (along with numerous research prototypes), licensed to 63 companies and institutions, and made available to medical societies, organizations, medical schools, and individuals. These atlases have been applied in education, research, and clinical applications. Hundreds of thousands of patients have been treated by using our atlases. Based on this experience, the first version of the holistic and reference atlas of the brain, head, and neck has been developed and made available. The atlas has been created from multispectral 3 and 7 Tesla and high-resolution CT in vivo scans. It is fully 3D, scalable, interactive, and highly detailed with about 3,000 labeled components. This atlas forms a foundation for the development of a multi-level molecular, cellular, anatomical, physiological, and behavioral brain atlas platform.

  3. Incidence trends of human papillomavirus-related head and neck cancer in Taiwan, 1995-2009.

    Science.gov (United States)

    Hwang, Tzer-Zen; Hsiao, Jenn-Ren; Tsai, Chia-Rung; Chang, Jeffrey S

    2015-07-15

    Recent studies suggested that human papillomavirus (HPV) is an emerging risk factor of head and neck cancer (HNC), particularly for oropharyngeal cancer. Studies from the West showed a rising trend of HPV-related HNC despite a decrease of the overall HNC incidence. In contrast, the overall HNC incidence in Taiwan has continued to rise. It is not clear whether the incidence trends of HPV-related HNC in Taiwan have a similar pattern to those from countries with an overall decreasing incidence of HNC. This study examined the incidence trends of HPV-related and HPV-unrelated HNC in Taiwan using data from the Taiwan Cancer Registry. Our results showed that the incidence trends of HPV-related and HPV-unrelated HNC in Taiwan both rose during 1995-2009. The incidence of HPV-related HNC (1.3 per 100,000 in 1995 to 3.3 in 2009, annual percentage change (APC) = 6.9, p Taiwan has continued to increase, the most rapid rise is in the HPV-related HNC. This suggests that similar to the Western world, HPV-related HNC is becoming an important public health issue in Taiwan. © 2014 UICC.

  4. Proteomics analyses of human optic nerve head astrocytes following biomechanical strain.

    Science.gov (United States)

    Rogers, Ronan S; Dharsee, Moyez; Ackloo, Suzanne; Sivak, Jeremy M; Flanagan, John G

    2012-02-01

    We investigate the role of glial cell activation in the human optic nerve caused by raised intraocular pressure, and their potential role in the development of glaucomatous optic neuropathy. To do this we present a proteomics study of the response of cultured, optic nerve head astrocytes to biomechanical strain, the magnitude and mode of strain based on previously published quantitative models. In this case, astrocytes were subjected to 3 and 12% stretches for either 2 h or 24 h. Proteomic methods included nano-liquid chromatography, tandem mass spectrometry, and iTRAQ labeling. Using controls for both stretch and time, a six-plex iTRAQ liquid chromatography- tandem MS (LC/MS/MS) experiment yielded 573 proteins discovered at a 95% confidence limit. The pathways included transforming growth factor β1, tumor necrosis factor, caspase 3, and tumor protein p53, which have all been implicated in the activation of astrocytes and are believed to play a role in the development of glaucomatous optic neuropathy. Confirmation of the iTRAQ analysis was performed by Western blotting of various proteins of interest including ANXA 4, GOLGA2, and αB-Crystallin.

  5. Proteomics Analyses of Human Optic Nerve Head Astrocytes Following Biomechanical Strain*

    Science.gov (United States)

    Rogers, Ronan S.; Dharsee, Moyez; Ackloo, Suzanne; Sivak, Jeremy M.; Flanagan, John G.

    2012-01-01

    We investigate the role of glial cell activation in the human optic nerve caused by raised intraocular pressure, and their potential role in the development of glaucomatous optic neuropathy. To do this we present a proteomics study of the response of cultured, optic nerve head astrocytes to biomechanical strain, the magnitude and mode of strain based on previously published quantitative models. In this case, astrocytes were subjected to 3 and 12% stretches for either 2 h or 24 h. Proteomic methods included nano-liquid chromatography, tandem mass spectrometry, and iTRAQ labeling. Using controls for both stretch and time, a six-plex iTRAQ liquid chromatography- tandem MS (LC/MS/MS) experiment yielded 573 proteins discovered at a 95% confidence limit. The pathways included transforming growth factor β1, tumor necrosis factor, caspase 3, and tumor protein p53, which have all been implicated in the activation of astrocytes and are believed to play a role in the development of glaucomatous optic neuropathy. Confirmation of the iTRAQ analysis was performed by Western blotting of various proteins of interest including ANXA 4, GOLGA2, and αB-Crystallin. PMID:22126795

  6. [Human papilloma viruses: other risk factor of head and neck carcinoma].

    Science.gov (United States)

    Woto-Gaye, G; M'Farrej, M K; Doh, K; Thiam, I; Touré, S; Diop, R; Dial, C

    2016-08-01

    Head and neck carcinoma (HNC) occupy the sixth place as the most frequent type of cancer worldwide. Next to alcohol and tobacco intoxication, other risk factors (RF) are suspected, including the human papilloma viruses (HPVs). The aim of this study was to highlight the prevalence of HPVs and histo-epidemiological characteristics of HNC HPV+ in Senegal. This is a prospective, multicenter preliminary study of 18 months (January 1, 2012-June 30, 2014). The cases of HNC histologically confirmed in Senegal were then sent to the bio-pathology department of the Curie Institute in Paris to search HPVs. In the 90 included cases, the PCR technique was successful in 54 cases (60%). HPVs were found in seven cases, that is, a prevalence of 13%. HPVs were associated with 5 cases of hypopharyngeal carcinoma and 2 cases of carcinoma of the oral cavity. Patients with HNC HPV+ had a median age of 42 years against 49 years for HPV-patients. Three patients (42.8%) with HPV+ carcinomas were smokers. Of the 47 HPV-patients, 40 patients (87.1%) had alcohol intoxication and/or smoking. The concept of oral sex was refuted by all our patients. Squamous cell carcinoma was the only histological type found. HPV+ cell carcinoma showed no specific histological appearance. HPVs are another certain RF of HNC in Senegal. The major therapeutic and prognostic impact of HPVinduced cancers requires the systematic search of the viruses by the PCR technique.

  7. Lycopene inhibits the cell proliferation and invasion of human head and neck squamous cell carcinoma.

    Science.gov (United States)

    Ye, Min; Wu, Qundan; Zhang, Min; Huang, Jinbei

    2016-10-01

    Lycopene has been shown to be associated with anticancer effects in numerous tumor types. However, the underlying mechanisms of lycopene in human head and neck squamous cell carcinoma (HNSCC) remain to be determined. The present study aimed to investigate the involvement of lycopene overload and the cytotoxic effects of lycopene on HNSCC cells, and to determine the possible mechanisms involved. Treatment with lycopene at a dose of >10 µM for >24 h inhibited the growth of FaDu and Cal27 cells in a time‑ and dose‑dependent manner. The clearest increase in growth inhibition was due to the apoptotic population being significantly increased. The invasion abilities decreased with 25 µM lycopene exerting significant inhibitory effects (Plycopene induced the upregulation of the pro‑apoptotic protein, B‑cell lymphoma‑associated X protein, and therefore, resulted in the inhibition of the protein kinase B and mitogen‑activated protein kinase signaling pathway. These data provided insights into the antitumor activity of lycopene in HNSCC cells.

  8. Controversies surrounding human papilloma virus infection, head & neck vs oral cancer, implications for prophylaxis and treatment.

    Science.gov (United States)

    Campisi, Giuseppina; Giovannelli, Lucia

    2009-03-30

    Head & Neck Cancer (HNC) represents the sixth most common malignancy worldwide and it is historically linked to well-known behavioural risk factors, i.e., tobacco smoking and/or the alcohol consumption. Recently, substantial evidence has been mounting that Human Papillomavirus (HPV) infection is playing an increasing important role in oral cancer. Because of the attention and clamor surrounding oral HPV infection and related cancers, as well as the use of HPV prophylactic vaccines, in this invited perspective the authors raise some questions and review some controversial issues on HPV infection and its role in HNC, with a particular focus on oral squamous cell carcinoma. The problematic definition and classification of HNC will be discussed, together with the characteristics of oral infection with oncogenic HPV types, the frequency of HPV DNA detection in HNC, the location of HPV-related tumours, the severity and prognosis of HPV-positive HNC, the diagnosis of oral HPV infection, common routes of oral infection and the likelihood of oro-genital HPV transmission, the prevention of HPV infection and novel therapeutic approaches.

  9. Susceptibility of human head and neck cancer cells to combined inhibition of glutathione and thioredoxin metabolism.

    Directory of Open Access Journals (Sweden)

    Arya Sobhakumari

    Full Text Available Increased glutathione (GSH and thioredoxin (Trx metabolism are mechanisms that are widely implicated in resistance of cancer cells to chemotherapy. The current study determined if simultaneous inhibition of GSH and Trx metabolism enhanced cell killing of human head and neck squamous cell carcinoma (HNSCC cells by a mechanism involving oxidative stress. Inhibition of GSH and Trx metabolism with buthionine sulfoximine (BSO and auranofin (AUR, respectively, induced significant decreases in clonogenic survival compared to either drug alone in FaDu, Cal-27 and SCC-25 HNSCC cells in vitro and in vivo in Cal-27 xenografts. BSO+AUR significantly increased glutathione and thioredoxin oxidation and suppressed peroxiredoxin activity in vitro. Pre-treatment with N-acetylcysteine completely reversed BSO+AUR-induced cell killing in FaDu and Cal-27 cells, while catalase and selenium supplementation only inhibited BSO+AUR-induced cell killing in FaDu cells. BSO+AUR decreased caspase 3/7 activity in HNSCC cells and significantly reduced the viability of both Bax/Bak double knockout (DKO and DKO-Bax reconstituted hematopoietic cells suggesting that necrosis was involved. BSO+AUR also significantly sensitized FaDu, Cal-27, SCC-25 and SQ20B cells to cell killing induced by the EGFR inhibitor Erlotinib in vitro. These results support the conclusion that simultaneous inhibition of GSH and Trx metabolism pathways induces oxidative stress and clonogenic killing in HNSCCs and this strategy may be useful in sensitizing HNSCCs to EGFR inhibitors.

  10. The role of human papillomavirus in head and neck cancer in Senegal.

    Science.gov (United States)

    Ndiaye, Cathy; Alemany, Laia; Diop, Yankhoba; Ndiaye, Nafissatou; Diémé, Marie-Joseph; Tous, Sara; Klaustermeier, Jo Ellen; Alejo, Maria; Castellsagué, Xavier; Bosch, F Xavier; Trottier, Helen; Sanjosé, Silvia de

    2013-04-17

    Exploring the presence and role of human papillomavirus (HPV) in head and neck cancer (HNC) is a necessary step to evaluate the potential impact of HPV prophylactic vaccines. To assess the prevalence and oncogenic role of HPV in HNC in Senegal. This is a multicenter cross-sectional study. Paraffin-embedded blocks of cases diagnosed with invasive HNC between 2002 and 2010 were collected from 4 pathology laboratories in Senegal. Presence of HPV DNA was determined by PCR and DEIA, and genotyping performed with LiPA25. Tubulin analysis was performed to assess DNA quality. HPV DNA-positive cases were tested for p16INK4a expression. A total of 117 cases were included in the analysis: 71% were men, mean age was 52 years old (SD ±18.3), and 96% of cases were squamous cell carcinoma. Analysis was performed on 41 oral cavity tumors, 64 laryngeal tumors, 5 oropharyngeal tumors and 7 pharyngeal tumors. Only four cases (3.4%; 95% CI = 0.9%-8.5%) harbored HPV DNA. HPV types detected were HPV16, HPV35 and HPV45. However, among HPV-positive cases, none showed p16INK4a overexpression. Our findings indicate that HPV DNA prevalence in HNC in Senegal is very low, suggesting that HPV is not a strong risk factor for these cancers. Additional larger studies are needed to confirm these findings and explore other potential risk factors specific to the region.

  11. Do you believe in phantoms?

    CERN Multimedia

    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...

  12. Anthropomorphic phantom materials

    International Nuclear Information System (INIS)

    White, D.R.; Constantinou, C.

    1982-01-01

    The need, terminology and history of tissue substitutes are outlined. Radiation properties of real tissues are described and simulation procedures are outlined. Recent tissue substitutes are described and charted, as are calculated radiation classifications. Manufacturing procedures and quality control are presented. Recent phantom studies are reviewed and a discussion recorded. Elemental compositions of the recommended tissue substitutes are charted with elemental composition given for each tissue substitute

  13. Solid water phantom

    International Nuclear Information System (INIS)

    Arguiropulo, M.Y.; Ghilardi Neto, T.; Pela, C.A.; Ghilardi, A.J.P.

    1992-01-01

    A phantom were developed for simulating water, based in plastics. The material was evaluated for different energies, and the measures of relative transmission showed that the transmission and the water were inside of 0,6% for gamma rays. The results of this new material were presented, showing that it could be used in photon beam calibration with energies on radiotherapy range. (C.G.C.)

  14. Trichostatin A, a histone deacetylase inhibitor, potentiated cytotoxic effect of lionizing radiation in human head and neck cancer cell lines

    International Nuclear Information System (INIS)

    Kim, Jin Ho; Shin, Jin Hee; Chie, Eui Kyu; Wu, Hong Gyun; Kim, Jae Sung; Kim, Il Han; Ha, Sung Whan; Park, Charn Il; Kang, Wee Saing

    2004-01-01

    We have previously reported that human glioblastoma cells are sensitized to radiation-induced death after their exposure to trichostatin A (TSA), a histone deacetylase inhibitor (HDAC-I), prior to the irradiation. We aimed to measure the magnitude of the radiosensitizing effect of TSA in human head and neck cancer cell lines. human head and neck cancer cell lines, HN-3 and HN-9, were exposed to 0, 50, 100, and 200 nM TSA for 18 hr prior to irradiation. Then, the TSA-treated cells were irradiated with 0, 2, 4, 6, and 8 Gy, and cell survival was measured by clonogenic assay. Pre-irradiation exposure to TSA was found to radiosensitize HN-3 and HN-9 cell lines. In HN-9 cells, the fraction surviving after 2 Gy (SF2) was significantly reduced by treatment of TSA at concentration as low as 50 nM. However, a treatment with 200 nM TSA was required to significantly decrease SF2 in the HN-3 cell line. SER of pre-irradiation treatment with 200 nM TSA was 1.84 in HN-3 and 7.24 in HN-9, respectively. Our results clearly showed that human head and neck cancer cell lines can be sensitized to ionizing radiation by pre-irradiation inhibition of histone deacetylase (HDAC) using TSA, and that this potentiation might well be a general phenomenon

  15. 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...... 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...... scale, ranging from 0 to 100, was 36 (range: 1–89). One-third of the patients experienced phantom pain every day. Chilliness, windy weather and psychological stress/fatigue were the most commonly reported triggers for pain. Conclusions: Phantom pain after eye amputation is relatively common. The pain...

  16. A computer-simulated liver phantom (virtual liver phantom) for multidetector computed tomography evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Funama, Yoshinori [Kumamoto University, Department of Radiological Sciences, School of Health Sciences, Kumamoto (Japan); Awai, Kazuo; Nakayama, Yoshiharu; Liu, Da; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Miyazaki, Osamu; Goto, Taiga [Hitachi Medical Corporation, Tokyo (Japan); Hori, Shinichi [Gate Tower Institute of Image Guided Therapy, Osaka (Japan)

    2006-04-15

    The purpose of study was to develop a computer-simulated liver phantom for hepatic CT studies. A computer-simulated liver phantom was mathematically constructed on a computer workstation. The computer-simulated phantom was calibrated using real CT images acquired by an actual four-detector CT. We added an inhomogeneous texture to the simulated liver by referring to CT images of chronically damaged human livers. The mean CT number of the simulated liver was 60 HU and we added numerous 5-to 10-mm structures with 60{+-}10 HU/mm. To mimic liver tumors we added nodules measuring 8, 10, and 12 mm in diameter with CT numbers of 60{+-}10, 60{+-}15, and 60{+-}20 HU. Five radiologists visually evaluated similarity of the texture of the computer-simulated liver phantom and a real human liver to confirm the appropriateness of the virtual liver images using a five-point scale. The total score was 44 in two radiologists, and 42, 41, and 39 in one radiologist each. They evaluated that the textures of virtual liver were comparable to those of human liver. Our computer-simulated liver phantom is a promising tool for the evaluation of the image quality and diagnostic performance of hepatic CT imaging. (orig.)

  17. Thermal effects of whole head submersion in cold water on nonshivering humans.

    Science.gov (United States)

    Pretorius, Thea; Bristow, Gerald K; Steinman, Alan M; Giesbrecht, Gordon G

    2006-08-01

    This study isolated the effect of whole head submersion in cold water, on surface heat loss and body core cooling, when the confounding effect of shivering heat production was pharmacologically eliminated. Eight healthy male subjects were studied in 17 degrees C water under four conditions: the body was either insulated or uninsulated, with the head either above the water or completely submersed in each body-insulation subcondition. Shivering was abolished with buspirone (30 mg) and meperidine (2.5 mg/kg), and subjects breathed compressed air throughout all trials. Over the first 30 min of immersion, exposure of the head increased core cooling both in the body-insulated conditions (head out: 0.47 +/- 0.2 degrees C, head in: 0.77 +/- 0.2 degrees C; P body-exposed conditions (head out: 0.84 +/- 0.2 degrees C and head in: 1.17 +/- 0.5 degrees C; P body surface area) in the body-exposed conditions increased total heat loss by only 10%. In both body-exposed and body-insulated conditions, head submersion increased core cooling rate much more (average of 42%) than it increased total heat loss. This may be explained by a redistribution of blood flow in response to stimulation of thermosensitive and/or trigeminal receptors in the scalp, neck and face, where a given amount of heat loss would have a greater cooling effect on a smaller perfused body mass. In 17 degrees C water, the head does not contribute relatively more than the rest of the body to surface heat loss; however, a cold-induced reduction of perfused body mass may allow this small increase in heat loss to cause a relatively larger cooling of the body core.

  18. 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.

  19. Comparison of the ANSI, RSD, KKH, and BRMD thyroid-neck phantoms for 125I thyroid monitoring.

    Science.gov (United States)

    Kramer, G H; Olender, G; Vlahovich, S; Hauck, B M; Meyerhof, D P

    1996-03-01

    The Human Monitoring Laboratory, which acts as the Canadian National Calibration Reference Centre for In Vivo Monitoring, has determined the performance characteristics of four thyroid phantoms for 125I thyroid monitoring. The phantoms were a phantom built to the specifications of the American National Standards Institute Standard N44.3; the phantom available from Radiology Support Devices; the phantom available from Kyoto Kagaku Hyohon; the phantom manufactured by the Human Monitoring Laboratory and known as the BRMD phantom. The counting efficiencies of the phantoms for 125I were measured at different phantom-to-detector distances. The anthropomorphic characteristics of the phantoms have been compared with the average man parameters. It was concluded that the BRMD, American National Standards Institute, and Radiology Support Devices phantoms have the same performance characteristics when the neck-to-detector distances are greater than 12 cm and all phantoms are essentially equivalent at 30 cm or more. The Kyoto Kagaku Hyohon phantom showed lower counting efficiencies at phantom-to-detector distances less than 30 cm. This was attributed to the design of the phantom. This study has also shown that the phantom need not be highly anthropomorphic provided the calibration is not performed at short neck-detector distances. Indeed, it might be possible to use t simple point source of 125I placed behind a 1.5 cm block of lucite at neck detector distances of 12 cm or more.

  20. Associations among human papillomavirus, inflammation, and fatigue in patients with head and neck cancer.

    Science.gov (United States)

    Xiao, Canhua; Beitler, Jonathan J; Higgins, Kristin A; Glazer, Toby; Huynh, Linh Kha; Paul, Sudeshna; Felger, Jennifer C; Wommack, Evanthia C; Saba, Nabil F; Shin, Dong M; Bruner, Deborah W; Miller, Andrew H

    2018-05-09

    Human papillomavirus (HPV) infection has contributed to an increased incidence of squamous cell carcinoma of the head and neck (SCCHN). Fatigue is a major side effect of SCCHN and its treatment. However, to the authors' knowledge, the association between HPV and fatigue has not been examined to date, nor is it known whether HPV influences biological mechanisms of fatigue, including inflammation. Patients with SCCHN who were without distant metastasis were assessed at baseline (pre-radiotherapy) and 1 month and 3 months postradiotherapy. Fatigue was measured using the Multidimensional Fatigue Inventory. Peripheral inflammation was assessed by plasma C-reactive protein (CRP), interleukin 1 receptor antagonist (IL-1ra), soluble tumor necrosis factor receptor 2 (sTNFR2), and IL-6. Mixed effect models were used to examine associations. A total of 94 patients who were newly diagnosed were enrolled; 53% had HPV-related tumors. Patients with HPV-unrelated tumors had higher fatigue and higher plasma CRP, sTNFR2, and IL-6 over time, especially at baseline and 3 months after intensity-modulated radiotherapy compared with those with HPV-related tumors (all P < .05). However, fatigue and plasma sTNFR2 increased more significantly from baseline to 1 month after radiotherapy in the HPV-related group compared with the HPV-unrelated group (both P < .01). Controlling for significant covariates, HPV status and inflammation were found to be independent predictors of fatigue over time. HPV status is an important marker of vulnerability to the behavioral and immune consequences of SCCHN and its treatment, providing support for different symptom management strategies. Special emphasis should be placed on addressing marked persistent fatigue in patients with HPV-unrelated tumors, whereas attention should be paid to the large increases in fatigue during treatment among patients with HPV-related tumors. Cancer 2018. © 2018 American Cancer Society. © 2018 American Cancer Society.

  1. Human papilloma virus prevalence in HIV patients with head and neck squamous cell carcinoma.

    Science.gov (United States)

    Picard, Annabelle; Badoual, Cécile; Hourseau, Muriel; Halimi, Caroline; Pere, Hélène; Dib, Fadia; Barry, Béatrix; Albert, Sébastien

    2016-05-15

    The implication of human papilloma virus (HPV) in head and neck squamous cell carcinoma (HNSCC) is well established, especially in oropharyngeal SCC. HIV patients have a higher risk of persistent HPV infection. We investigated the role of HPV in HNSCC carcinogenesis in HIV population. Retrospective monocentric study. We studied HIV patients who presented with HNSCC between 1994 and 2014. For each patient, tumor characteristics, HIV disease, and survival information were collected. Tumor HPV testing was performed using p16 immunohistochemistry (IHC), in-situ hybridization and PCR. We assessed the percentage of HPV in this population of HIV patients with HNSCC and compared HIV disease characteristics based on HPV status. Forty-seven patients were included: 11 women/36 men, the median age was 50 years. Tumor HPV testing was performed in 40 patients. Tumors were located in oropharynx (32%), oral cavity (32%), larynx (21%), and hypopharynx (11%). At the time of diagnosis, median CD4 level was 385 cells/μl, 31% of the patients were stage (Centers for Disease Control, stage C). The percentage of HPV linked to HNSCC for all locations in HIV patients was 30% (n = 12). HPV16 accounted for 50% of all HPV genotypes. HPV positive status was associated with a CD4 nadir of less than 200 (P = 0.026), but not with CD4 level at time of diagnosis (P = 0.414). HPV-negative tumors tend to be associated with poorer 5-year overall survival (hazard ratio = 2.9, P = 0.0711). HPV plays a critical role in HNSCC development in HIV population. HIV immunodeficiency may increase HPV persistence and progression of HNSCC.

  2. Feasibility and implementation of a literature information management system for human papillomavirus in head and neck cancers with imaging.

    Science.gov (United States)

    Wu, Dee H; Matthiesen, Chance L; Alleman, Anthony M; Fournier, Aaron L; Gunter, Tyler C

    2014-01-01

    This work examines the feasibility and implementation of information service-orientated architecture (ISOA) on an emergent literature domain of human papillomavirus, head and neck cancer, and imaging. From this work, we examine the impact of cancer informatics and generate a full set of summarizing clinical pearls. Additionally, we describe how such an ISOA creates potential benefits in informatics education, enhancing utility for creating enduring digital content in this clinical domain.

  3. A Novel Cellular Handset Design for an Enhanced Antenna Performance and a Reduced SAR in the Human Head

    Directory of Open Access Journals (Sweden)

    Salah I. Al-Mously

    2008-01-01

    Full Text Available This paper presents a novel cellular handset design with a bottom-mounted short loaded-whip antenna. This new handset design is modeled and simulated using a finite difference time-domain (FDTD-based platform SEMCAD. The proposed handset is based on a current commercially available bar-phone type with a curvature shape, keypad positioned above the screen, and top-mounted antenna. The specific absorption rates (SARs are determined computationally in the specific anthropomorphic mannequin (SAM and anatomically correct model of a human head when exposed to the EM-field radiation of the proposed cellular handset and the handset with top-mounted antenna. The two cellular handsets are simulated to operate at both GSM standards, 900 MHz as well as 1800 MHz, having different antenna dimensions and intput power of 0.6 W and 0.125 W, respectively. The proposed human hand holding the two handset models is a semirealistic hand model consists of three tissues: skin, muscle, and bone. The simulations are conducted with handset positions based on the IEEE standard 1528-2003. The results show that the proposed handset has a significant improvement of antenna efficiency when it is hand-held close to head, as compared with the handset of top-mounted antenna. Also, the results show that a significant reduction of the induced SAR in the human head-tissues can be achieved with the proposed handset.

  4. SAR analysis of a needle type applicator made from a shape memory alloy using 3-D anatomical human head model

    International Nuclear Information System (INIS)

    Kubo, Mitsunori; Mimoto, Naoki; Hirashima, Taku; Morita, Emi; Shindo, Yasuhiro; Kato, Kazuo; Takahashi, Hideaki; Uzuka, Takeo; Fujii, Yukihiko

    2009-01-01

    This paper describes the possibility of a new heating method with a needle applicator made of a shape memory alloy (SMA) to expand the heating area for interstitial brain tumor hyperthermia treatments. The purpose of the study described here is to show the capability of the method to expand a defined heating region with the developed three-dimensional (3-D) anatomical human head model using the finite element method (FEM). One major disadvantage of radiofrequency (RF) interstitial hyperthermia treatment is that this heating method has a small heating area. To overcome this problem, a new type of needle made of a SMA was developed. The specific absorption rate (SAR) distributions of this proposed method, when applied to the 3-D anatomical human head model reconstructed from two-dimensional (2-D) MRI and X-ray CT images, were calculated with computer simulations. The calculated SAR distributions showed no unexpected hot spots within the model. The heated area was localized around the tumor. These results suggest that the proposed heating method using the SMA needle applicator and the developed method for reconstructing a 3-D anatomical human head model are capable of being used for invasive brain tumor hyperthermia treatments. (author)

  5. Effects of cooling portions of the head on human thermoregulatory response.

    Science.gov (United States)

    Katsuura, T; Tomioka, K; Harada, H; Iwanaga, K; Kikuchi, Y

    1996-03-01

    Seven healthy young male students participated in this study. Each subject sat on a chair in an anteroom at 25 degrees C for 30 min and then entered a climatic chamber, controlled at 40 degrees C and R.H. 50%, and sat on a chair for 90 min. Cooling of frontal portion including the region around the eyes (FC), occipital portion (OC), and temporal portion (TC) began after 50 min of entering. An experiment without head cooling (NC) was also made for the control measurement. Thermal comfort and thermal sensation were improved by head cooling, but response was the same regardless of portion cooled. Although rectal temperature, mean skin temperature and heart rate showed no significant effect due to head cooling, forearm skin blood flow (FBF), sweat rate (SR), and body weight loss (delta Wt) had a tendency to be depressed. FBF in FC and TC decreased during head cooling, but that in OC and NC did not change significantly, while SR in FC was depressed. delta Wt showed total sweating to decrease by FC and TC, and FC to have greater inhibitory effect on sweating than OC. Thermal strain was evaluated by the modified Craig Index (I(s)). I(s) in FC decreased significantly more than in NC. Cooling of other portions of the head had no significant effect on I(s). Cooling of the frontal portion of the head may thus be concluded to have the most effect on thermoregulatory response in a hot environment.

  6. Construction of cardiac anthropomorphic phantom for simulation of radiological exams

    International Nuclear Information System (INIS)

    Bandeira, C.K.; Vieira Neto, H.; Vieira, M.P.M.M.

    2017-01-01

    Phantoms are simulating objects of structures of the human body and can be applied in the quality control and calibration of radiological equipment. The aim of the work is the development of a cardiac anthropomorphic phantom to assist in the elaboration of protocols of dynamic studies that demonstrate the blood circulation inside the cardiac chambers. For the construction of the phantom was used latex, applied in layers on an anatomical model of heart, having been constructed the cardiac chambers and atrioventricular valves. Cardiac chambers were connected to the cannulas for fluid injection and simulation of the circulatory system. The constructed phantom presents anthropomorphic characteristics and allows the circulation of the fluid without reflux, but the thickness of the catheters used does not yet allow flows of greater order of magnitude. This phantom has the potential to be used in the dynamic simulation of cardiac exams, contributing to the elaboration and adequacy of computed tomography protocols

  7. From fish to modern humans--comparative anatomy, homologies and evolution of the head and neck musculature.

    Science.gov (United States)

    Diogo, R; Abdala, V; Lonergan, N; Wood, B A

    2008-10-01

    In a recent paper Diogo (2008) reported the results of the first part of an investigation of the comparative anatomy, homologies and evolution of the head and neck muscles of osteichthyans (bony fish + tetrapods). That report mainly focused on actinopterygian fish, but also compared these fish with certain non-mammalian sarcopterygians. The present paper focuses mainly on sarcopterygians, and particularly on how the head and neck muscles have evolved during the transitions from sarcopterygian fish and non-mammalian tetrapods to monotreme and therian mammals, including modern humans. The data obtained from our dissections of the head and neck muscles of representative members of sarcopterygian fish, amphibians, reptiles, monotremes and therian mammals, such as rodents, tree-shrews, colugos and primates, including modern humans, are compared with the information available in the literature. Our observations and comparisons indicate that the number of mandibular and true branchial muscles (sensu this work) present in modern humans is smaller than that found in mammals such as tree-shrews, rats and monotremes, as well as in reptiles such as lizards. Regarding the pharyngeal musculature, there is an increase in the number of muscles at the time of the evolutionary transition leading to therian mammals, but there was no significant increase during the transition leading to the emergence of higher primates and modern humans. The number of hypobranchial muscles is relatively constant within the therian mammals we examined, although in this case modern humans have more muscles than other mammals. The number of laryngeal and facial muscles in modern humans is greater than that found in most other therian taxa. Interestingly, modern humans possess peculiar laryngeal and facial muscles that are not present in the majority of the other mammalian taxa; this seems to corroborate the crucial role played by vocal communication and by facial expressions in primate and especially in

  8. Phantom breast syndrome

    Directory of Open Access Journals (Sweden)

    Ramesh

    2009-01-01

    Full Text Available Phantom breast syndrome is a type of condition in which patients have a sensation of residual breast tissue and can include both non-painful sensations as well as phantom breast pain. The incidence varies in different studies, ranging from approximately 30% to as high as 80% of patients after mastectomy. It seriously affects quality of life through the combined impact of physical disability and emotional distress. The breast cancer incidence rate in India as well as Western countries has risen in recent years while survival rates have improved; this has effectively increased the number of women for whom post-treatment quality of life is important. In this context, chronic pain following treatment for breast cancer surgery is a significantly under-recognized and under-treated problem. Various types of chronic neuropathic pain may arise following breast cancer surgery due to surgical trauma. The cause of these syndromes is damage to various nerves during surgery. There are a number of assumed factors causing or perpetuating persistent neuropathic pain after breast cancer surgery. Most well-established risk factors for developing phantom breast pain and other related neuropathic pain syndromes are severe acute postoperative pain and greater postoperative use of analgesics. Based upon current evidence, the goals of prophylactic strategies could first target optimal peri-operative pain control and minimizing damage to nerves during surgery. There is some evidence that chronic pain and sensory abnormalities do decrease over time. The main group of oral medications studied includes anti-depressants, anticonvulsants, opioids, N-methyl-D-asparate receptor antagonists, mexilitine, topical lidocaine, cannabinoids, topical capsaicin and glysine antagonists. Neuromodulation techniques such as motor cortex stimulation, spinal cord stimulation, and intrathecal drug therapies have been used to treat various neuropathic pain syndromes.

  9. Simplified realistic human head model for simulating Tumor Treating Fields (TTFields).

    Science.gov (United States)

    Wenger, Cornelia; Bomzon, Ze'ev; Salvador, Ricardo; Basser, Peter J; Miranda, Pedro C

    2016-08-01

    Tumor Treating Fields (TTFields) are alternating electric fields in the intermediate frequency range (100-300 kHz) of low-intensity (1-3 V/cm). TTFields are an anti-mitotic treatment against solid tumors, which are approved for Glioblastoma Multiforme (GBM) patients. These electric fields are induced non-invasively by transducer arrays placed directly on the patient's scalp. Cell culture experiments showed that treatment efficacy is dependent on the induced field intensity. In clinical practice, a software called NovoTalTM uses head measurements to estimate the optimal array placement to maximize the electric field delivery to the tumor. Computational studies predict an increase in the tumor's electric field strength when adapting transducer arrays to its location. Ideally, a personalized head model could be created for each patient, to calculate the electric field distribution for the specific situation. Thus, the optimal transducer layout could be inferred from field calculation rather than distance measurements. Nonetheless, creating realistic head models of patients is time-consuming and often needs user interaction, because automated image segmentation is prone to failure. This study presents a first approach to creating simplified head models consisting of convex hulls of the tissue layers. The model is able to account for anisotropic conductivity in the cortical tissues by using a tensor representation estimated from Diffusion Tensor Imaging. The induced electric field distribution is compared in the simplified and realistic head models. The average field intensities in the brain and tumor are generally slightly higher in the realistic head model, with a maximal ratio of 114% for a simplified model with reasonable layer thicknesses. Thus, the present pipeline is a fast and efficient means towards personalized head models with less complexity involved in characterizing tissue interfaces, while enabling accurate predictions of electric field distribution.

  10. The point spread function of the human head and its implications for transcranial current stimulation

    International Nuclear Information System (INIS)

    Dmochowski, Jacek P; Bikson, Marom; Parra, Lucas C

    2012-01-01

    Rational development of transcranial current stimulation (tCS) requires solving the ‘forward problem’: the computation of the electric field distribution in the head resulting from the application of scalp currents. Derivation of forward models has represented a major effort in brain stimulation research, with model complexity ranging from spherical shells to individualized head models based on magnetic resonance imagery. Despite such effort, an easily accessible benchmark head model is greatly needed when individualized modeling is either undesired (to observe general population trends as opposed to individual differences) or unfeasible. Here, we derive a closed-form linear system which relates the applied current to the induced electric potential. It is shown that in the spherical harmonic (Fourier) domain, a simple scalar multiplication relates the current density on the scalp to the electric potential in the brain. Equivalently, the current density in the head follows as the spherical convolution between the scalp current distribution and the point spread function of the head, which we derive. Thus, if one knows the spherical harmonic representation of the scalp current (i.e. the electrode locations and current intensity to be employed), one can easily compute the resulting electric field at any point inside the head. Conversely, one may also readily determine the scalp current distribution required to generate an arbitrary electric field in the brain (the ‘backward problem’ in tCS). We demonstrate the simplicity and utility of the model with a series of characteristic curves which sweep across a variety of stimulation parameters: electrode size, depth of stimulation, head size and anode–cathode separation. Finally, theoretically optimal montages for targeting an infinitesimal point in the brain are shown. (paper)

  11. Development of age-specific Japanese physical phantoms for dose evaluation in infant CT examinations

    International Nuclear Information System (INIS)

    Yamauchi-Kawaura, C.; Fujii, K.; Imai, K.; Ikeda, M.; Akahane, K.; Obara, S.; Yamauchi, M.; Narai, K.; Katsu, T.

    2016-01-01

    Secondary to the previous development of age-specific Japanese head phantoms, the authors designed Japanese torso phantoms for dose assessment in infant computed tomography (CT) examinations and completed a Japanese 3-y-old head-torso phantom. For design of age-specific torso phantoms (0, 0.5, 1 and 3 y old), anatomical structures were measured from CT images of Japanese infant patients. From the CT morphometry, it was found that rib cages of Japanese infants were smaller than those in Europeans and Americans. Radiophotoluminescence glass dosemeters were used for dose measurement of a 3-y-old head-torso phantom. To examine the validity of the developed phantom, organ and effective doses by the in-phantom dosimetry system were compared with simulation values in a web-based CT dose calculation system (WAZA-ARI). The differences in doses between the two systems were <20 % at the doses of organs within scan regions and effective doses in head, chest and abdomino-pelvic CT examinations. (authors)

  12. Factors affecting the aluminium content of human femoral head and neck.

    Science.gov (United States)

    Zioła-Frankowska, Anetta; Dąbrowski, Mikołaj; Kubaszewski, Łukasz; Rogala, Piotr; Frankowski, Marcin

    2015-11-01

    Tissues for the study were obtained intraoperatively during hip replacement procedures from 96 patients. In all the cases, the indication for this treatment was primary or secondary degenerative changes in the hip joint. The subject of the study was the head and neck of the femur, resected in situ. Aluminium concentrations measured in femoral head and neck samples from patients aged between 25 and 91 were varied. Statistical methods were applied to determine the variations in relation to the parameters from the background survey. Significant differences in the aluminium content of femoral head samples were observed between patients under and over 60 years of age. Based on the results, it was confirmed that the aluminium accumulates in bones over a lifetime. The study showed that the content of aluminium in the head and neck of the femur depends on the factors such as: type of medicines taken, contact with chemicals at work, differences in body anatomy and sex. The study on the levels of aluminium in bones and the factors affecting its concentration is a valuable source of information for further research on the role of aluminium in bone diseases. Based on the investigations, it was found that the GF-AAS technique is the best analytical tool for routine analysis of aluminium in complex matrix samples. The use of femoral heads in the investigations was approved by the Bioethics Committee of the University of Medical Sciences in Poznań (Poland). Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Reconstruction of voxel phantoms for skin dosimetry

    International Nuclear Information System (INIS)

    Antunes, Paula Cristina Guimaraes

    2010-01-01

    Radiotherapy is a therapeutic modality that utilizes ionizing radiation for the destruction of neoplastic human cells. One of the requirements for this treatment methodology success lays on the appropriate use of planning systems, which performs, among other information, the patient's dose distribution estimate. Nowadays, transport codes have been providing huge subsidies to these planning systems, once it enables specific and accurate patient organ and tissue dosimetry. The model utilized by these codes to describe the human anatomy in a realistic way is known as voxel phantoms, which are represented by discrete volume elements (voxels) directly associated to tomographic data. Nowadays, voxel phantoms doable of being inserted and processed by the transport code MCNP (Monte Carlo N-Particle) presents a 3-4 mm image resolution; however, such resolution limits some thin body structure discrimination, such as skin. In this context, this work proposes a calculus routine that discriminates this region with thickness and localization in the voxel phantoms similar to the real, leading to an accurate dosimetric skin dose assessment by the MCNP code. Moreover, this methodology consists in manipulating the voxel phantoms volume elements by segmenting and subdividing it in different skin thickness. In addition to validate the skin dose calculated data, a set of experimental evaluations with thermoluminescent dosimeters were performed in an anthropomorphic phantom. Due to significant differences observed on the dose distribution of several skin representations, it was found that is important to discriminate the skin thickness similar to the real. The presented methodology is useful to obtain an accurate skin dosimetric evaluation for several radiotherapy procedures, with particular interest on the electron beam radiotherapy, in which highlights the whole body irradiation therapy (TSET), a procedure under implementation at the Hospital das Clinicas da Faculdade de Medicina da

  14. Conceiving Human Interaction by Visualising Depth Data of Head Pose Changes and Emotion Recognition via Facial Expressions

    Directory of Open Access Journals (Sweden)

    Grigorios Kalliatakis

    2017-07-01

    Full Text Available Affective computing in general and human activity and intention analysis in particular comprise a rapidly-growing field of research. Head pose and emotion changes present serious challenges when applied to player’s training and ludology experience in serious games, or analysis of customer satisfaction regarding broadcast and web services, or monitoring a driver’s attention. Given the increasing prominence and utility of depth sensors, it is now feasible to perform large-scale collection of three-dimensional (3D data for subsequent analysis. Discriminative random regression forests were selected in order to rapidly and accurately estimate head pose changes in an unconstrained environment. In order to complete the secondary process of recognising four universal dominant facial expressions (happiness, anger, sadness and surprise, emotion recognition via facial expressions (ERFE was adopted. After that, a lightweight data exchange format (JavaScript Object Notation (JSON is employed, in order to manipulate the data extracted from the two aforementioned settings. Motivated by the need to generate comprehensible visual representations from different sets of data, in this paper, we introduce a system capable of monitoring human activity through head pose and emotion changes, utilising an affordable 3D sensing technology (Microsoft Kinect sensor.

  15. Epstein-Barr virus and human papillomavirus infections and genotype distribution in head and neck cancers.

    Directory of Open Access Journals (Sweden)

    Zeyi Deng

    Full Text Available To investigate the prevalence, genotypes, and prognostic values of Epstein-Barr virus (EBV and human papillomavirus (HPV infections in Japanese patients with different types of head and neck cancer (HNC.HPV and EBV DNA, EBV genotypes and LMP-1 variants, and HPV mRNA expression were detected by PCR from fresh-frozen HNC samples. HPV genotypes were determined by direct sequencing, and EBV encoded RNA (EBER was examined by in situ hybridization.Of the 209 HNC patients, 63 (30.1% had HPV infection, and HPV-16 was the most common subtype (86.9%. HPV E6/E7 mRNA expression was found in 23 of 60 (38.3% HPV DNA-positive cases detected. The site of highest prevalence of HPV was the oropharynx (45.9%. Among 146 (69.9% HNCs in which EBV DNA was identified, 107 (73.3% and 27 (18.5% contained types A and B, respectively, and 124 (84.9% showed the existence of del-LMP-1. However, only 13 (6.2% HNCs were positive for EBER, 12 (92.3% of which derived from the nasopharynx. Co-infection of HPV and EBER was found in only 1.0% of HNCs and 10.0% of NPCs. Kaplan-Meier survival analysis showed significantly better disease-specific and overall survival in the HPV DNA+/mRNA+ oropharyngeal squamous cell carcinoma (OPC patients than in the other OPC patients (P = 0.027 and 0.017, respectively. Multivariate analysis showed that stage T1-3 (P = 0.002 and HPV mRNA-positive status (P = 0.061 independently predicted better disease-specific survival. No significant difference in disease-specific survival was found between the EBER-positive and -negative NPC patients (P = 0.155.Our findings indicate that co-infection with HPV and EBV is rare in HNC. Oropharyngeal SCC with active HPV infection was related to a highly favorable outcome, while EBV status was not prognostic in the NPC cohort.

  16. SU-F-T-292: Imaging and Radiation Oncology Core (IROC) Houston QA Center’s Anthropomorphic Phantom Program

    International Nuclear Information System (INIS)

    Mehrens, H; Lewis, B; Lujano, C; Nguyen, T; Hernandez, N; Alvarez, P; Molineu, A; Followill, D

    2016-01-01

    Purpose: To describe the results of IROC Houston’s international and domestic end-to-end QA phantom irradiations. Methods: IROC Houston has anthropomorphic lung, liver, head and neck, prostate, SRS and spine phantoms that are used for credentialing and quality assurance purposes. The phantoms include structures that closely mimic targets and organs at risk and are made from tissue equivalent materials: high impact polystyrene, solid water, cork and acrylic. Motion tables are used to mimic breathing motion for some lung and liver phantoms. Dose is measured with TLD and radiochromic film in various planes within the target of the phantoms. Results: The most common phantom requested is the head and neck followed by the lung phantom. The head and neck phantom was sent to 800 domestic and 148 international sites between 2011 and 2015, with average pass rates of 89% and 92%, respectively. During the past five years, a general upward trend exists regarding demand for the lung phantom for both international and domestic sites with international sites more than tripling from 5 (2011) to 16 (2015) and domestic sites doubling from 66 (2011) to 152 (2015). The pass rate for lung phantoms has been consistent from year to year despite this large increase in the number of phantoms irradiated with an average pass rate of 85% (domestic) and 95% (international) sites. The percentage of lung phantoms used in combination with motions tables increased from 38% to 79% over the 5 year time span. Conclusion: The number of domestic and international sites irradiating the head and neck and lung phantoms continues to increase and the pass rates remained constant. These end-to-end QA tests continue to be a crucial part of clinical trial credentialing and institution quality assurance. This investigation was supported by IROC grant CA180803 awarded by the NCI.

  17. SU-F-T-292: Imaging and Radiation Oncology Core (IROC) Houston QA Center’s Anthropomorphic Phantom Program

    Energy Technology Data Exchange (ETDEWEB)

    Mehrens, H; Lewis, B; Lujano, C; Nguyen, T; Hernandez, N; Alvarez, P; Molineu, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To describe the results of IROC Houston’s international and domestic end-to-end QA phantom irradiations. Methods: IROC Houston has anthropomorphic lung, liver, head and neck, prostate, SRS and spine phantoms that are used for credentialing and quality assurance purposes. The phantoms include structures that closely mimic targets and organs at risk and are made from tissue equivalent materials: high impact polystyrene, solid water, cork and acrylic. Motion tables are used to mimic breathing motion for some lung and liver phantoms. Dose is measured with TLD and radiochromic film in various planes within the target of the phantoms. Results: The most common phantom requested is the head and neck followed by the lung phantom. The head and neck phantom was sent to 800 domestic and 148 international sites between 2011 and 2015, with average pass rates of 89% and 92%, respectively. During the past five years, a general upward trend exists regarding demand for the lung phantom for both international and domestic sites with international sites more than tripling from 5 (2011) to 16 (2015) and domestic sites doubling from 66 (2011) to 152 (2015). The pass rate for lung phantoms has been consistent from year to year despite this large increase in the number of phantoms irradiated with an average pass rate of 85% (domestic) and 95% (international) sites. The percentage of lung phantoms used in combination with motions tables increased from 38% to 79% over the 5 year time span. Conclusion: The number of domestic and international sites irradiating the head and neck and lung phantoms continues to increase and the pass rates remained constant. These end-to-end QA tests continue to be a crucial part of clinical trial credentialing and institution quality assurance. This investigation was supported by IROC grant CA180803 awarded by the NCI.

  18. Head and neck squamous cell carcinoma and its correlation with human papillomavirus in people living with HIV: a systematic review.

    Science.gov (United States)

    Ceccarelli, Manuela; Rullo, Emmanuele Venanzi; Facciolà, Alessio; Madeddu, Giordano; Cacopardo, Bruno; Taibi, Rosaria; D'Aleo, Francesco; Pinzone, Marilia Rita; Picerno, Isa; di Rosa, Michele; Visalli, Giuseppa; Condorelli, Fabrizio; Nunnari, Giuseppe; Pellicanò, Giovanni Francesco

    2018-03-30

    Over the last 20 years we assisted to an increase in the mean age of People Living with HIV and their comorbidities. Especially, there was an increase in Human Papillomavirus-related head and neck squamous cell carcinomas. Despite their increasing incidence in HIV-positive people, mechanisms that lead to their development and progression are only partially understood. The aim of this review is to identify key data and factors about HPV-related head and neck squamous cell carcinoma in HIV-seropositive patients. Systematic search and review of the relevant literature-peer-reviewed and grey-was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. We included in our review only the 35 full-text articles we considered the most substantial. It is mandatory to improve our knowledge about the interactions existing between HPV and HIV, and about their actions on oral mucosa immune system.

  19. Preliminary Study on Hybrid Computational Phantom for Radiation Dosimetry Based on Subdivision Surface

    International Nuclear Information System (INIS)

    Jeong, Jong Hwi; Choi, Sang Hyoun; Cho, Sung Koo; Kim, Chan Hyeong

    2007-01-01

    The anthropomorphic computational phantoms are classified into two groups. One group is the stylized phantoms, or MIRD phantoms, which are based on mathematical representations of the anatomical structures. The shapes and positions of the organs and tissues in these phantoms can be adjusted by changing the coefficients of the equations in use. The other group is the voxel phantoms, which are based on tomographic images of a real person such as CT, MR and serially sectioned color slice images from a cadaver. Obviously, the voxel phantoms represent the anatomical structures of a human body much more realistically than the stylized phantoms. A realistic representation of anatomical structure is very important for an accurate calculation of radiation dose in the human body. Consequently, the ICRP recently has decided to use the voxel phantoms for the forthcoming update of the dose conversion coefficients. However, the voxel phantoms also have some limitations: (1) The topology and dimensions of the organs and tissues in a voxel model are extremely difficult to change, and (2) The thin organs, such as oral mucosa and skin, cannot be realistically modeled unless the voxel resolution is prohibitively high. Recently, a new approach has been implemented by several investigators. The investigators converted their voxel phantoms to hybrid computational phantoms based on NURBS (Non-Uniform Rational B-Splines) surface, which is smooth and deformable. It is claimed that these new phantoms have the flexibility of the stylized phantom along with the realistic representations of the anatomical structures. The topology and dimensions of the anatomical structures can be easily changed as necessary. Thin organs can be modeled without affecting computational speed or memory requirement. The hybrid phantoms can be also used for 4-D Monte Carlo simulations. In this preliminary study, the external shape of a voxel phantom (i.e., skin), HDRK-Man, was converted to a hybrid computational

  20. Early components of the human vestibulo-ocular response to head rotation: latency and gain

    NARCIS (Netherlands)

    H. Collewijn (Han); J.B.J. Smeets (Jeroen)

    2000-01-01

    textabstractTo characterize vestibulo-ocular reflex (VOR) properties in the time window in which contributions by other systems are minimal, eye movements during the first 50-100 ms after the start of transient angular head accelerations ( approximately 1000 degrees

  1. Eye-head stabilization mechanism for a humanoid robot tested on human inertial data

    DEFF Research Database (Denmark)

    Vannucci, Lorenzo; Falotico, Egidio; Tolu, Silvia

    2016-01-01

    they keep the image stationary on the retina. In this work we present the first complete model of eye-head stabilization based on the coordination of VCR and VOR. The model is provided with learning and adaptation capabilities based on internal models. Tests on a simulated humanoid platform replicating...

  2. Comparison of acute cardiovascular responses to water immersion and head-down tilt in humans

    DEFF Research Database (Denmark)

    Shiraishi, Makoto; Schou, Morten; Gybel, Mikkel

    2002-01-01

    The hypothesis was tested that acute water immersion to the neck (WI) compared with 6 degrees head-down tilt (HDT) induces a more pronounced distension of the heart and lower plasma levels of vasoconstrictor hormones. Ten healthy males underwent 30 min of HDT, WI, and a seated control (randomized...

  3. A Wearable Goggle Navigation System for Dual-Mode Optical and Ultrasound Localization of Suspicious Lesions: Validation Studies Using Tissue-Simulating Phantoms and an Ex Vivo Human Breast Tissue Model.

    Directory of Open Access Journals (Sweden)

    Zeshu Zhang

    Full Text Available Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG-fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting.

  4. Neutron production in a spherical phantom aboard ISS

    International Nuclear Information System (INIS)

    Tasbaz, A.; Machrafi, R.

    2012-01-01

    As part of an ongoing research program on radiation monitoring on International Space Station (ISS) that was established to analyze the radiation exposure levels onboard the ISS using different radiation instruments and a spherical phantom to simulate human body. Monte Carlo transport code was used to simulate the interaction of high energy protons and neutrons with the spherical phantom currently onboard ISS. The phantom has been exposed to individual proton energies and to a spectrum of neutrons. The internal to external neutron flux ratio was calculated and compared to the experimental data, recently, measured on the ISS. (author)

  5. Construction of average adult Japanese voxel phantoms for dose assessment

    International Nuclear Information System (INIS)

    Sato, Kaoru; Takahashi, Fumiaki; Satoh, Daiki; Endo, Akira

    2011-12-01

    The International Commission on Radiological Protection (ICRP) adopted the adult reference voxel phantoms based on the physiological and anatomical reference data of Caucasian on October, 2007. The organs and tissues of these phantoms were segmented on the basis of ICRP Publication 103. In future, the dose coefficients for internal dose and dose conversion coefficients for external dose calculated using the adult reference voxel phantoms will be widely used for the radiation protection fields. On the other hand, the body sizes and organ masses of adult Japanese are generally smaller than those of adult Caucasian. In addition, there are some cases that the anatomical characteristics such as body sizes, organ masses and postures of subjects influence the organ doses in dose assessment for medical treatments and radiation accident. Therefore, it was needed to use human phantoms with average anatomical characteristics of Japanese. The authors constructed the averaged adult Japanese male and female voxel phantoms by modifying the previously developed high-resolution adult male (JM) and female (JF) voxel phantoms. It has been modified in the following three aspects: (1) The heights and weights were agreed with the Japanese averages; (2) The masses of organs and tissues were adjusted to the Japanese averages within 10%; (3) The organs and tissues, which were newly added for evaluation of the effective dose in ICRP Publication 103, were modeled. In this study, the organ masses, distances between organs, specific absorbed fractions (SAFs) and dose conversion coefficients of these phantoms were compared with those evaluated using the ICRP adult reference voxel phantoms. This report provides valuable information on the anatomical and dosimetric characteristics of the averaged adult Japanese male and female voxel phantoms developed as reference phantoms of adult Japanese. (author)

  6. Voxel anthropomorphic phantoms: review of models used for ionising radiation dosimetry

    International Nuclear Information System (INIS)

    Lemosquet, A.; Carlan, L. de; Clairand, I.

    2003-01-01

    Computational anthropomorphic phantoms have been used since the 1970's for dosimetric calculations. Realistic geometries are required for this operation, resulting in the development of ever more accurate phantoms. Voxel phantoms, consisting of a set of small-volume elements, appeared towards the end of the 1980's, and significantly improved on the original mathematical models. Voxel phantoms are models of the human body, obtained using computed tomography (CT) or magnetic resonance images (MRI). These phantoms are an extremely accurate representation of the human anatomy. This article provides a review of the literature available on the development of these phantoms and their applications in ionising radiation dosimetry. The bibliographical study has shown that there is a wide range of phantoms, covering various characteristics of the general population in terms of sex, age or morphology, and that they are used in applications relating to all aspects of ionising radiation. (author)

  7. Bioassay Phantoms Using Medical Images and Computer Aided Manufacturing

    International Nuclear Information System (INIS)

    Xu, X. Geroge

    2011-01-01

    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.

  8. ICRU activity in the field of phantoms in diagnostic radiology

    International Nuclear Information System (INIS)

    Wambersie, A.; White, D.R.

    1992-01-01

    The ICRU Report on 'Phantoms and Computational Models in Radiation Therapy, Diagnosis and Protection' is presented. The Report contains a major section on human anatomy, from fetus to adult with the variations due to ethnic origin. Tolerance levels for the phantoms (composition, dimensions) are proposed and quality assurance programs are outlined. The report contains extensive appendices: human anatomical data and full specification of over 80 phantoms and computational models. ICRU Report 46 on 'Photon, electron, proton and neutron interaction data for body tissues' is closely related to the field of phantoms. It is a logical continuation on ICRU Report 44 (1989) on 'Tissue substitutes in radiation dosimetry and measurements' and contains the interaction data for more than 100 tissues, from fetal to adult, including some diseased tissues. (author)

  9. Density distribution of currents induced inside the brain in the head part of the human model exposed to power frequency electric field

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, Atsuo [Yongo National Collage of Technology (Japan); Isaka, Katsuo [University of Tokushima (Japan)

    1999-07-01

    The health effect of the weak current induced in the human body as a result of the interaction between human body and power frequency electric fields has been investigated. However, the current density inside the head part tissues of the human body exposed to the electric fields has rarely been discussed. In this paper, the finite element method is applied to the analysis of the current density distribution of the head part composed of scalp, skull, cerebrospinal liquid and brain tissues. The basic characteristics of the current density distributions of the brain in the asymmetrical human model have been made clear. (author)

  10. Effects of face/head and whole body cooling during passive heat stress on human somatosensory processing.

    Science.gov (United States)

    Nakata, Hiroki; Namba, Mari; Kakigi, Ryusuke; Shibasaki, Manabu

    2017-06-01

    We herein investigated the effects of face/head and whole body cooling during passive heat stress on human somatosensory processing recorded by somatosensory-evoked potentials (SEPs) at C4' and Fz electrodes. Fourteen healthy subjects received a median nerve stimulation at the left wrist. SEPs were recorded at normothermic baseline (Rest), when esophageal temperature had increased by ~1.2°C (heat stress: HS) during passive heating, face/head cooling during passive heating (face/head cooling: FHC), and after HS (whole body cooling: WBC). The latencies and amplitudes of P14, N20, P25, N35, P45, and N60 at C4' and P14, N18, P22, and N30 at Fz were evaluated. Latency indicated speed of the subcortical and cortical somatosensory processing, while amplitude reflected the strength of neural activity. Blood flow in the internal and common carotid arteries (ICA and CCA, respectively) and psychological comfort were recorded in each session. Increases in esophageal temperature due to HS significantly decreased the amplitude of N60, psychological comfort, and ICA blood flow in the HS session, and also shortened the latencies of SEPs (all, P body temperature. Copyright © 2017 the American Physiological Society.

  11. Oral sex and human papilloma virus-related head and neck squamous cell cancer: a review of the literature.

    Science.gov (United States)

    Shah, Ankit; Malik, Akshat; Garg, Apurva; Mair, Manish; Nair, Sudhir; Chaturvedi, Pankaj

    2017-11-01

    Head neck squamous cell carcinomas (HNSCCs) are a significant cause of morbidity and mortality all around the world. Just like tobacco and alcohol, Human papilloma virus (HPV) infection is now recognized to play a role in the pathogenesis of a subset of HNSCCs. Unprotected sexual behaviours with the HPV carrier plays an important role in transmission of this virus. The global incidence of head and neck cancers is declining, but the incidence of HPV related head and neck cancers is rapidly increasing over the last few decades. However, most institutions do not mandate documentation of sexual history or counselling of patients regarding sexual practices like they do for tobacco and alcohol addictions in HNSCC patients. The aim of this review of literature is to analyse if there is a strong evidence to correlate oral sex with HPV related HNSCC and counsel the patient's regarding sexual behaviours. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  12. Toxicity of Head-and-Neck Radiation Therapy in Human Immunodeficiency Virus-Positive Patients

    International Nuclear Information System (INIS)

    Sanfilippo, Nicholas J.; Mitchell, James; Grew, David; DeLacure, Mark

    2010-01-01

    Purpose: To examine the acute morbidity of high dose head and neck RT and CRT in patients with infected with HIV. Methods and Materials: All HIV-positive patients who underwent radiation therapy for head and neck cancer in our department between 2004 and 2008 were reviewed. Treatment related data were examined. All treatments were delivered with megavoltage photon beams or electron beams. Patients were evaluated by an attending radiation oncologist for toxicity and response on a weekly basis during therapy and monthly after treatment in a multidisciplinary clinic. Acute toxicities were recorded using the Radiation Therapy and Oncology Group (RTOG) common toxicity criteria. Response to treatment was based on both physical exam as well as post-treatment imaging as indicated. Results: Thirteen patients who underwent RT with a diagnosis of HIV were identified. Median age was 53 years and median follow-up was 22 months. Twelve had squamous cell carcinoma and one had lymphoproliferative parotiditis. Median radiation dose was 66.4 Gy and median duration of treatment was 51 days. The median number of scheduled radiotherapy days missed was zero (range 0 to 7). One patient (8%) developed Grade 4 confluent moist desquamation. Eight patients (61%) developed Grade 3 toxicity. Conclusion: Based on our results, HIV-positive individuals appear to tolerate treatment for head and neck cancer, with toxicity similar to that in HIV-negative individuals.

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

    International Nuclear Information System (INIS)

    Nogueira, Luciana B.; Campos, Tarcisio P.R.

    2013-01-01

    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)

  14. Phantoms and computational models in therapy, diagnosis and protection

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    The development of realistic body phantoms and computational models is strongly dependent on the availability of comprehensive human anatomical data. This information is often missing, incomplete or not easily available. Therefore, emphasis is given in the Report to organ and body masses and geometries. The influence of age, sex and ethnic origins in human anatomy is considered. Suggestions are given on how suitable anatomical data can be either extracted from published information or obtained from measurements on the local population. Existing types of phantoms and computational models used with photons, electrons, protons and neutrons are reviewed in this Report. Specifications of those considered important to the maintenance and development of reliable radiation dosimetry and measurement are given. The information provided includes a description of the phantom or model, together with diagrams or photographs and physical dimensions. The tissues within body sections are identified and the tissue substitutes used or recommended are listed. The uses of the phantom or model in radiation dosimetry and measurement are outlined. The Report deals predominantly with phantom and computational models representing the human anatomy, with a short Section devoted to animal phantoms in radiobiology

  15. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    Science.gov (United States)

    Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

    2015-12-01

    The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements-including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth-were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light-tissue interactions and characterizing biophotonic system performance.

  16. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    Science.gov (United States)

    Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

    2015-01-01

    Abstract. The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements—including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth—were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light–tissue interactions and characterizing biophotonic system performance. PMID:26662064

  17. Vortex-ring mixing as a measure of diastolic function of the human heart: Phantom validation and initial observations in healthy volunteers and patients with heart failure.

    Science.gov (United States)

    Töger, Johannes; Kanski, Mikael; Arvidsson, Per M; Carlsson, Marcus; Kovács, Sándor J; Borgquist, Rasmus; Revstedt, Johan; Söderlind, Gustaf; Arheden, Håkan; Heiberg, Einar

    2016-06-01

    To present and validate a new method for 4D flow quantification of vortex-ring mixing during early, rapid filling of the left ventricle (LV) as a potential index of diastolic dysfunction and heart failure. 4D flow mixing measurements were validated using planar laser-induced fluorescence (PLIF) in a phantom setup. Controls (n = 23) and heart failure patients (n = 23) were studied using 4D flow at 1.5T (26 subjects) or 3T (20 subjects) to determine vortex volume (VV) and inflowing volume (VVinflow ). The volume mixed into the vortex-ring was quantified as VVmix-in = VV-VVinflow . The mixing ratio was defined as MXR = VVmix-in /VV. Furthermore, we quantified the fraction of the end-systolic volume (ESV) mixed into the vortex-ring (VVmix-in /ESV) and the fraction of the LV volume at diastasis (DV) occupied by the vortex-ring (VV/DV). PLIF validation of MXR showed fair agreement (R(2) = 0.45, mean ± SD 1 ± 6%). MXR was higher in patients compared to controls (28 ± 11% vs. 16 ± 10%, P Vortex-ring mixing can be quantified using 4D flow. The differences in mixing parameters observed between controls and patients motivate further investigation as indices of diastolic dysfunction. J. Magn. Reson. Imaging 2016;43:1386-1397. © 2015 Wiley Periodicals, Inc.

  18. Phantom dosimetry at 15 MV conformal radiation therapy

    International Nuclear Information System (INIS)

    Thompson, Larissa; Campos, Tarcisio P.R.; Dias, Humberto G.

    2013-01-01

    The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)

  19. Phantom dosimetry at 15 MV conformal radiation therapy

    International Nuclear Information System (INIS)

    Thompson, Larissa; Campos, Tarcisio P.R.

    2015-01-01

    The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)

  20. Calculation of conversion coefficients for effective dose by using voxel phantoms with defined genus for radiodiagnostic common examinations

    International Nuclear Information System (INIS)

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

    2004-01-01

    Patient exposure from radiological examinations is usually quantified in terms of average absorbed dose or equivalent dose to certain radiosensitive organs of the human body. As these quantities cannot be measured in vivo, it is common practice to use physical or computational exposure models, which simulate the exposure to the patient in order to determine not only the quantities of interest (absorbed or equivalent dose), but also at the same time measurable quantities for the exposure conditions given. The ratio between a quantity of interest and a measurable quantity is called a conversion coefficient (CC), which is a function of the source and field parameters (tube voltage, filtration, field size, field position, focus-to-skin distance, etc.), the anatomical properties of the phantom, the elemental composition of relevant body tissues, and the radiation transport method applied. As the effective dose represents a sum over 23 risk-weighted organ and tissue equivalent doses, its determination practically implies the measurement or calculation of a complete distribution of equivalent doses throughout the human body. This task can be resolved most efficiently by means of computational exposure models, which consist of a virtual representation of the human body, also called phantom, connected to a Monte Carlo radiation transport computer code. The recently introduced MAX (Male Adult voXel) and FAXht (Female Adult voXel) head+trunk phantoms have been chosen for this task. With respect to their anatomical properties these phantoms correspond fairly well to the data recommended by the ICRP for the Reference Adult Male and Female. (author)

  1. Monitoring Autophagy Immunohistochemically and Ultrastructurally during Human Head and Neck Carcinogenesis. Relationship with the DNA Damage Response Pathway †

    Science.gov (United States)

    Havaki, Sophia; Vlachou, Vassiliki; Zampetidis, Christos P.; Selemenakis, Platonas; Kotsinas, Athanassios; Mavrogonatou, Eleni; Rizou, Sophia V.; Kyrodimos, Euthymios; Evangelou, Konstantinos; Kletsas, Dimitris; Giatromanolaki, Alexandra; Gorgoulis, Vassilis G.

    2017-01-01

    Autophagy is a catabolic process that preserves cellular homeostasis. Its exact role during carcinogenesis is not completely defined. Specifically in head and neck cancer, such information from clinical settings that comprise the whole spectrum of human carcinogenesis is very limited. Towards this direction, we examined the in situ status of the autophagy-related factors, Beclin-1, microtubule-associated protein 1 light chain 3, member B (LC3B) and sequestosome 1/p62 (p62) in clinical material covering all histopathological stages of human head and neck carcinogenesis. This material is unique as each panel of lesions is derived from the same patient and moreover we have previously assessed it for the DNA damage response (DDR) activation status. Since Beclin-1, LC3B and p62 reflect the nucleation, elongation and degradation stages of autophagy, respectively, their combined immunohistochemical (IHC) expression profiles could grossly mirror the autophagic flux. This experimental approach was further corroborated by ultrastructural analysis, applying transmission electron microscopy (TEM). The observed Beclin-1/LC3B/p62 IHC patterns, obtained from serial sections analysis, along with TEM findings are suggestive of a declined authophagic activity in preneoplastic lesions that was restored in full blown cancers. Correlating these findings with DDR status in the same pathological stages are indicative of: (i) an antitumor function of autophagy in support to that of DDR, possibly through energy deprivation in preneoplastic stages, thus preventing incipient cancer cells from evolving; and (ii) a tumor-supporting role in the cancerous stage. PMID:28880214

  2. Schneiderian membrane detachment using transcrestal hydrodynamic ultrasonic cavitational sinus lift: a human cadaver head study and histologic analysis.

    Science.gov (United States)

    Troedhan, Angelo; Kurrek, Andreas; Wainwright, Marcel; Jank, Siegfried

    2014-08-01

    Recent studies have suggested the osteogenic layer of the periosteum at the base of the sinus membrane to play a key role in bone regeneration after sinus lift procedures. Thus, atraumatic detachment of the sinus membrane with an intact periosteum seems mandatory. The present histologic study of fresh human cadaver heads investigated the detachment behavior and histologic integrity of the detached periosteum after application of the transcrestal hydrodynamic ultrasonic cavitational sinus lift (tHUCSL-INTRALIFT). A total of 15 sinuses in 8 fresh human cadaver heads were treated using tHUCSL-INTRALIFT. After surgery, they were checked macroscopically for damage to the sinus membrane and then processed for histologic inspection under light microscopy. A total of 150 histologic specimens, randomly selected from the core surgical sites, were investigated using hematoxylin-eosin (HE), Azan, and trichrome staining. None of the 150 inspected specimens showed any perforation or dissection of the periosteum from the subepithelial connective tissue and respiratory epithelium and were fully detached from the bony antrum floor. The connecting Sharpey fibers revealed to be cleanly separated from the sinus floor in all specimens. The results of the present study suggest tHUCSL-INTRALIFT should be used to perform predictable and safe detachment of the periosteum from the bony sinus floor as a prerequisite for undisturbed and successful physiologic subantral bone regeneration. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  3. The sex ratio distortion in the human head louse is conserved over time

    Directory of Open Access Journals (Sweden)

    Biliński Szczepan M

    2004-05-01

    Full Text Available Abstract Background At the turn of the 19th century the first observations of a female-biased sex ratio in broods and populations of the head louse, Pediculus humanus capitis, had been reported. A study by Buxton in 1940 on the sex ratio of lice on prisoners in Ceylon is still today the subject of reanalyses. This sex ratio distortion had been detected in ten different countries. In the last sixty years no new data have been collected, especially on scalp infestations under economically and socially more developed conditions. Results Here we report a female bias of head lice in a survey of 480 school children in Argentina. This bias is independent of the intensity of the pediculosis, which makes local mate competition highly unlikely as the source of the aberrant sex ratio; however, other possible adaptive mechanisms cannot be discounted. These lice as well as lice from pupils in Britain were carrying several strains of the endosymbiotic bacterium Wolbachia pipientis, one of the most wide spread intracellular sex ratio distorters. Similar Wolbachia strains are also present in the pig louse, Haematopinus suis, suggesting that this endosymbiont might have a marked influence on the biology of the whole order. The presence of a related obligate nutritional bacterium in lice prevents the investigation of a causal link between sex ratio and endosymbionts. Conclusions Regardless of its origin, this sex ratio distortion in head lice that has been reported world wide, is stable over time and is a remarkable deviation from the stability of frequency-dependent selection of Fisher's sex ratio. A female bias first reported in 1898 is still present over a hundred years and a thousand generations later.

  4. Heads Up

    Science.gov (United States)

    ... Connect with Us HEADS UP Apps Reshaping the Culture Around Concussion in Sports Get HEADS UP on Your Web Site Concussion ... HEADS UP on your web site! Create a culture of safety for young athletes Officials, learn how you can ... UP to Providers HEADS UP to Youth Sports HEADS UP to School Sports HEADS UP to ...

  5. SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

    International Nuclear Information System (INIS)

    Ehler, E; Higgins, P; Dusenbery, K

    2014-01-01

    Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use

  6. SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

    Energy Technology Data Exchange (ETDEWEB)

    Ehler, E; Higgins, P; Dusenbery, K [University of Minnesota, Minneapolis, MN (United States)

    2014-06-15

    Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use.

  7. Development of realistic chest phantom for calibration of in-vivo plutonium counting facilities

    International Nuclear Information System (INIS)

    Shirotani, Takashi

    1987-06-01

    We have developed realistic chest phantom with removable model organs. The phantom is a torso and is terminated just above the femoral region. Tissue equivalent materials used in the phantom have been made of polyurethane with different amounts of ester of phosphoric acid, in order to simulate human soft tissues such as muscle, muscle-adipose mixtures and cartilage. Lung simulant has been made of foamed polyurethane. Capsulized small sources can be inserted into the holes, drilled in each sliced section of the model organ. Counting efficiencies, obtained with a pair of 12 cm diameter phoswich detectors set above the phantom chest, are 0.195 cpm/nCi for Pu-239 and 44.07 cpm/nCi for Am-241, respectively. The results agree well with efficiencies obtained with IAEA-Phantom. We conclude that the phantom can be used as a standard phantom for the calibration of Pu chest counting equipment. (author)

  8. Absorbed fractions in a voxel-based phantom calculated with the MCNP-4B code.

    Science.gov (United States)

    Yoriyaz, H; dos Santos, A; Stabin, M G; Cabezas, R

    2000-07-01

    A new approach for calculating internal dose estimates was developed through the use of a more realistic computational model of the human body. The present technique shows the capability to build a patient-specific phantom with tomography data (a voxel-based phantom) for the simulation of radiation transport and energy deposition using Monte Carlo methods such as in the MCNP-4B code. MCNP-4B absorbed fractions for photons in the mathematical phantom of Snyder et al. agreed well with reference values. Results obtained through radiation transport simulation in the voxel-based phantom, in general, agreed well with reference values. Considerable discrepancies, however, were found in some cases due to two major causes: differences in the organ masses between the phantoms and the occurrence of organ overlap in the voxel-based phantom, which is not considered in the mathematical phantom.

  9. Variations of the attachment of the superior head of human lateral pterygoid muscle.

    Science.gov (United States)

    Antonopoulou, Maria; Iatrou, Ioannis; Paraschos, Alexandros; Anagnostopoulou, Sophia

    2013-09-01

    The superior head of the lateral pterygoid muscle (LPM), is closely related to the temporomandibular joint (TMJ) and plays a role in the aetiology of temporomandibular disorders. Increased activity of this muscle has been implicated in the anterior displacement of the TMJ disc. However, there is uncertainty about the manner of the LPM attachment to the disc-condyle complex. The aim of this study was to investigate the exact anatomy of the attachment of the superior head of the LPM (SLPM) to the disc-condyle complex of the TMJ. Thirty-six TMJs were examined - both sides of 18 Greek cadavers (eight males and 10 females, mean age 79.6 years). Examination of the attachment of the SLPM was undertaken viewed under the dissecting microscope. Variation in the attachment of the SLPM was categorized into three types: in type I, the SLPM inserted into the condyle and the disc-capsule complex (55.5%). In type II, the SLPM only inserted into the condyle (27.8%). In type III, the SLPM inserted purely into the disc-capsule complex (16.7%). This study demonstrates that there are three different attachment types of the SLPM to the disc-condyle complex. The type III variation could be involved in the TMJ pathology. The knowledge of the variations of the SLPM attachment could be useful for precise surgical and pharmaceutical approaches. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  10. 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 tooth ... such as a specialist in oral medicine or orofacial pain. The information contained in this monograph is for ...

  11. Influence of stiffness and shape of contact surface on skull fractures and biomechanical metrics of the human head of different population underlateral impacts.

    Science.gov (United States)

    Shaoo, Debasis; Deck, Caroline; Yoganandan, Narayan; Willinger, Rémy

    2015-07-01

    The objective of this study was to determine the responses of 5th-percentile female, and 50th- and 95th-percentile male human heads during lateral impacts at different velocities and determine the role of the stiffness and shape of the impacting surface on peak forces and derived skull fracture metrics. A state-of-the-art validated finite element (FE) head model was used to study the influence of different population human heads on skull fracture for lateral impacts. The mass of the FE head model was altered to match the adult size dummies. Numerical simulations of lateral head impacts for 45 cases (15 experiments×3 different population human heads) were performed at velocities ranging from 2.4 to 6.5m/s and three impacting conditions (flat and cylindrical 90D; and flat 40D padding). The entire force-time signals from simulations were compared with experimental mean and upper/lower corridors at each velocity, stiffness (40 and 90 durometer) and shapes (flat and cylindrical) of the impacting surfaces. Average deviation of peak force from the 50th male to 95th male and 5th female were 6.4% and 10.6% considering impacts on the three impactors. These results indicate hierarchy of variables which can be used in injury mitigation efforts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Effect of Recombinant Human Deoxyribonuclease on Oropharyngeal Secretions in Patients With Head-and-Neck Cancers Treated With Radiochemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mittal, Bharat B., E-mail: bmittal@nmh.org [Department of Radiation Oncology, Northwestern University, Robert H. Lurie Comprehensive Cancer Center, Chicago, Illinois (United States); Wang, Edward [Department of Surgery, Northwestern University, Robert H. Lurie Comprehensive Cancer Center, Chicago, Illinois (United States); Sejpal, Samir [Department of Radiation Oncology, Northwestern University, Robert H. Lurie Comprehensive Cancer Center, Chicago, Illinois (United States); Agulnik, Mark [Section of Medical Oncology, Northwestern University, Robert H. Lurie Comprehensive Cancer Center, Chicago, Illinois (United States); Mittal, Amit [Yale University, New Haven, Connecticut (United States); Harris, Kirk [Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado (United States)

    2013-10-01

    Purpose: The current study examined the effect of recombinant human deoxyribonuclease (rhDNase) on quality of life (QOL) measures, clinical improvement, and DNA content of thick oropharyngeal secretions (OPS) in patients with head-and-neck (H and N) cancers. Methods and Materials: Thirty-six patients with local-regional advanced H and N cancer receiving chemoradiationtherapy (CRT) were randomized to receive either placebo or rhDNase. Endpoints included MD Anderson Symptom Inventory-Head and Neck (MDASI-HN) and Functional Assessment of Cancer Therapy–Head and Neck (FACT-NH) scores, along with clinical assessment and DNA concentration of OPS. Results: There were no statistically significant differences in patients' QOL outcomes over the study period. Both groups showed an increase in symptom and interference scores, although patients in the rhDNase group showed a greater decline in both scores during the 3 months posttreatment. Similarly, both groups showed a decline in physical and functional well being but recovered in the 3 months posttreatment follow-up, with the rhDNase group exhibiting speedier recovery. Patients in the rhDNase group exhibited significant clinical improvement in OPS, blindly assessed by a physician, compared with the placebo group (67% vs 27%, respectively; P=.046). The rhDNase group showed no change in OPS-DNA concentration, although the placebo group showed a significant increase in DNA concentration during the drug trial (P=.045). There was no differences in acute toxicities between the 2 groups. Conclusions: Our preliminary data suggest that rhDNase did not significantly improve study primary endpoints of QOL measures compared with the placebo group. However, there was a significant improvement in secondary endpoints of clinically assessed OPS and DNA concentration compared with placebo in H and N cancer patients treated with CRT. Further investigation in larger numbers of patients is warranted.

  13. Radiosensitivity of primary tumour cultures as a determinant of curability of human head and neck cancers

    International Nuclear Information System (INIS)

    Peters, L.J.; Tofilon, P.J.; Goepfert, H.; Brock, W.A.

    1989-01-01

    Between November 1985 and November 1987, 31 patients with squamous cell carcinomas of the head and neck who were treated on protocol by surgery and post-operative radiotherapy at the University of Texas M. D. Anderson Cancer Center had radiosensitivity measurements made on primary cultures of the surgical specimens using the Adhesive Tumour Cell Culture System. The parameter of cell survival at 2 Gy (S 2 ) was correlated with the clinical outcome independently of pathological risk factors. All five recurrences have been in patients with S 2 values >0.3 (p = 0.08). Evidence of significant intratumoral heterogeneity of cellular radiosensitivity in vitro was demonstrated in one of four cultures tested. Mathematical modelling suggests that in the absence of marked heterogeneity, the S 2 parameter is likely to be more robust than other radiobiologically based assays in predicting clinical treatment outcome. (author)

  14. 'Goats that stare at men'--revisited: do dwarf goats alter their behaviour in response to eye visibility and head direction of a human?

    Science.gov (United States)

    Nawroth, Christian; von Borell, Eberhard; Langbein, Jan

    2016-05-01

    Being able to recognise when one is being observed by someone else is thought to be adaptive during cooperative or competitive events. In particular for prey species, this ability should be of use in the context of predation. A previous study reported that goats (Capra aegagrus hircus) alter their behaviour according to the body and head orientation of a human experimenter. During a food anticipation task, an experimenter remained in a particular posture for 30 s before delivering a reward, and the goats' active anticipation and standing alert behaviour were analysed. To further evaluate the specific mechanisms at work, we here present two additional test conditions. In particular, we investigated the effects of the eye visibility and head orientation of a human experimenter on the behaviour of the goats (N = 7). We found that the level of the subjects' active anticipatory behaviour was highest in the conditions where the experimenter was directing his head and body towards the goat ('Control' and 'Eyes closed' conditions), but the anticipatory behaviour was significantly decreased when the body ('Head only') or the head and body of the experimenter were directed away from the subject ('Back' condition). For standing alert, we found no significant differences between the three conditions in which the experimenter was directing his head towards the subject ('Control', 'Eyes closed' and 'Head only'). This lack of differences in the expression of standing alert suggests that goats evaluate the direction of a human's head as an important cue in their anticipatory behaviour. However, goats did not respond to the visibility of the experimenter's eyes alone.

  15. Whole-body CT in polytrauma patients: the effect of arm position on abdominal image quality when using a human phantom

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Pil-Hyun [Yonsei University, Wonju (Korea, Republic of); Wonju Christian Hospital, Wonju (Korea, Republic of); Kim, Hee-Joung; Lee, Chang-Lae; Kim, Dae-Hong [Yonsei University, Wonju (Korea, Republic of); Lee, Won-Hyung; Jeon, Sung-Su [Wonju Christian Hospital, Wonju (Korea, Republic of)

    2012-06-15

    For a considerable number of emergency computed tomography (CT) scans, patients are unable to position their arms above their head due to traumatic injuries. The arms-down position has been shown to reduce image quality with beam-hardening artifacts in the dorsal regions of the liver, spleen, and kidneys, rendering these images non-diagnostic. The purpose of this study was to evaluate the effect of arm position on the image quality in patients undergoing whole-body CT. We acquired CT scans with various acquisition parameters at voltages of 80, 120, and 140 kVp and an increasing tube current from 200 to 400 mAs in 50 mAs increments. The image noise and the contrast assessment were considered for quantitative analyses of the CT images. The image noise (IN), the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and the coefficient of variation (COV) were evaluated. Quantitative analyses of the experiments were performed with CT scans representative of five different arm positions. Results of the CT scans acquired at 120 kVp and 250 mAs showed high image quality in patients with both arms raised above the head (SNR: 12.4, CNR: 10.9, and COV: 8.1) and both arms flexed at the elbows on the chest (SNR: 11.5, CNR: 10.2, and COV: 8.8) while the image quality significantly decreased with both arms in the down position (SNR: 9.1, CNR: 7.6, and COV: 11). Both arms raised, one arm raised, and both arms flexed improved the image quality compared to arms in the down position by reducing beam-hardening and streak artifacts caused by the arms being at the side of body. This study provides optimal methods for achieving higher image quality and lower noise in abdominal CT for trauma patients.

  16. Whole-body CT in polytrauma patients: The effect of arm position on abdominal image quality when using a human phantom

    Science.gov (United States)

    Jeon, Pil-Hyun; Kim, Hee-Joung; Lee, Chang-Lae; Kim, Dae-Hong; Lee, Won-Hyung; Jeon, Sung-Su

    2012-06-01

    For a considerable number of emergency computed tomography (CT) scans, patients are unable to position their arms above their head due to traumatic injuries. The arms-down position has been shown to reduce image quality with beam-hardening artifacts in the dorsal regions of the liver, spleen, and kidneys, rendering these images non-diagnostic. The purpose of this study was to evaluate the effect of arm position on the image quality in patients undergoing whole-body CT. We acquired CT scans with various acquisition parameters at voltages of 80, 120, and 140 kVp and an increasing tube current from 200 to 400 mAs in 50 mAs increments. The image noise and the contrast assessment were considered for quantitative analyses of the CT images. The image noise (IN), the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and the coefficient of variation (COV) were evaluated. Quantitative analyses of the experiments were performed with CT scans representative of five different arm positions. Results of the CT scans acquired at 120 kVp and 250 mAs showed high image quality in patients with both arms raised above the head (SNR: 12.4, CNR: 10.9, and COV: 8.1) and both arms flexed at the elbows on the chest (SNR: 11.5, CNR: 10.2, and COV: 8.8) while the image quality significantly decreased with both arms in the down position (SNR: 9.1, CNR: 7.6, and COV: 11). Both arms raised, one arm raised, and both arms flexed improved the image quality compared to arms in the down position by reducing beam-hardening and streak artifacts caused by the arms being at the side of body. This study provides optimal methods for achieving higher image quality and lower noise in abdominal CT for trauma patients.

  17. Whole-body CT in polytrauma patients: the effect of arm position on abdominal image quality when using a human phantom

    International Nuclear Information System (INIS)

    Jeon, Pil-Hyun; Kim, Hee-Joung; Lee, Chang-Lae; Kim, Dae-Hong; Lee, Won-Hyung; Jeon, Sung-Su

    2012-01-01

    For a considerable number of emergency computed tomography (CT) scans, patients are unable to position their arms above their head due to traumatic injuries. The arms-down position has been shown to reduce image quality with beam-hardening artifacts in the dorsal regions of the liver, spleen, and kidneys, rendering these images non-diagnostic. The purpose of this study was to evaluate the effect of arm position on the image quality in patients undergoing whole-body CT. We acquired CT scans with various acquisition parameters at voltages of 80, 120, and 140 kVp and an increasing tube current from 200 to 400 mAs in 50 mAs increments. The image noise and the contrast assessment were considered for quantitative analyses of the CT images. The image noise (IN), the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and the coefficient of variation (COV) were evaluated. Quantitative analyses of the experiments were performed with CT scans representative of five different arm positions. Results of the CT scans acquired at 120 kVp and 250 mAs showed high image quality in patients with both arms raised above the head (SNR: 12.4, CNR: 10.9, and COV: 8.1) and both arms flexed at the elbows on the chest (SNR: 11.5, CNR: 10.2, and COV: 8.8) while the image quality significantly decreased with both arms in the down position (SNR: 9.1, CNR: 7.6, and COV: 11). Both arms raised, one arm raised, and both arms flexed improved the image quality compared to arms in the down position by reducing beam-hardening and streak artifacts caused by the arms being at the side of body. This study provides optimal methods for achieving higher image quality and lower noise in abdominal CT for trauma patients.

  18. A methodology to develop computational phantoms with adjustable posture for WBC calibration

    Science.gov (United States)

    Ferreira Fonseca, T. C.; Bogaerts, R.; Hunt, John; Vanhavere, F.

    2014-11-01

    A Whole Body Counter (WBC) is a facility to routinely assess the internal contamination of exposed workers, especially in the case of radiation release accidents. The calibration of the counting device is usually done by using anthropomorphic physical phantoms representing the human body. Due to such a challenge of constructing representative physical phantoms a virtual calibration has been introduced. The use of computational phantoms and the Monte Carlo method to simulate radiation transport have been demonstrated to be a worthy alternative. In this study we introduce a methodology developed for the creation of realistic computational voxel phantoms with adjustable posture for WBC calibration. The methodology makes use of different software packages to enable the creation and modification of computational voxel phantoms. This allows voxel phantoms to be developed on demand for the calibration of different WBC configurations. This in turn helps to study the major source of uncertainty associated with the in vivo measurement routine which is the difference between the calibration phantoms and the real persons being counted. The use of realistic computational phantoms also helps the optimization of the counting measurement. Open source codes such as MakeHuman and Blender software packages have been used for the creation and modelling of 3D humanoid characters based on polygonal mesh surfaces. Also, a home-made software was developed whose goal is to convert the binary 3D voxel grid into a MCNPX input file. This paper summarizes the development of a library of phantoms of the human body that uses two basic phantoms called MaMP and FeMP (Male and Female Mesh Phantoms) to create a set of male and female phantoms that vary both in height and in weight. Two sets of MaMP and FeMP phantoms were developed and used for efficiency calibration of two different WBC set-ups: the Doel NPP WBC laboratory and AGM laboratory of SCK-CEN in Mol, Belgium.

  19. A methodology to develop computational phantoms with adjustable posture for WBC calibration

    International Nuclear Information System (INIS)

    Fonseca, T C Ferreira; Vanhavere, F; Bogaerts, R; Hunt, John

    2014-01-01

    A Whole Body Counter (WBC) is a facility to routinely assess the internal contamination of exposed workers, especially in the case of radiation release accidents. The calibration of the counting device is usually done by using anthropomorphic physical phantoms representing the human body. Due to such a challenge of constructing representative physical phantoms a virtual calibration has been introduced. The use of computational phantoms and the Monte Carlo method to simulate radiation transport have been demonstrated to be a worthy alternative. In this study we introduce a methodology developed for the creation of realistic computational voxel phantoms with adjustable posture for WBC calibration. The methodology makes use of different software packages to enable the creation and modification of computational voxel phantoms. This allows voxel phantoms to be developed on demand for the calibration of different WBC configurations. This in turn helps to study the major source of uncertainty associated with the in vivo measurement routine which is the difference between the calibration phantoms and the real persons being counted. The use of realistic computational phantoms also helps the optimization of the counting measurement. Open source codes such as MakeHuman and Blender software packages have been used for the creation and modelling of 3D humanoid characters based on polygonal mesh surfaces. Also, a home-made software was developed whose goal is to convert the binary 3D voxel grid into a MCNPX input file. This paper summarizes the development of a library of phantoms of the human body that uses two basic phantoms called MaMP and FeMP (Male and Female Mesh Phantoms) to create a set of male and female phantoms that vary both in height and in weight. Two sets of MaMP and FeMP phantoms were developed and used for efficiency calibration of two different WBC set-ups: the Doel NPP WBC laboratory and AGM laboratory of SCK-CEN in Mol, Belgium. (paper)

  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

  1. CT images of an anthropomorphic and anthropometric male pelvis phantom

    International Nuclear Information System (INIS)

    Matos, Andrea S.D. de; Campos, Tarcisio P.R. de

    2009-01-01

    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

  2. Distribution of elastic fibers in the head and neck: a histological study using late-stage human fetuses

    Science.gov (United States)

    Kinoshita, Hideaki; Umezawa, Takashi; Omine, Yuya; Kasahara, Masaaki; Rodríguez-Vázquez, José Francisco; Murakami, Gen

    2013-01-01

    There is little or no information about the distribution of elastic fibers in the human fetal head. We examined this issue in 15 late-stage fetuses (crown-rump length, 220-320 mm) using aldehyde-fuchsin and elastica-Masson staining, and we used the arterial wall elastic laminae and external ear cartilages as positive staining controls. The posterior pharyngeal wall, as well as the ligaments connecting the laryngeal cartilages, contained abundant elastic fibers. In contrast with the sphenomandibular ligament and the temporomandibular joint disk, in which elastic fibers were partly present, the discomalleolar ligament and the fascial structures around the pterygoid muscles did not have any elastic fibers. In addition, the posterior marginal fascia of the prestyloid space did contain such fibers. Notably, in the middle ear, elastic fibers accumulated along the tendons of the tensor tympani and stapedius muscles and in the joint capsules of the ear ossicle articulations. Elastic fibers were not seen in any other muscle tendons or vertebral facet capsules in the head and neck. Despite being composed of smooth muscle, the orbitalis muscle did not contain any elastic fibers. The elastic fibers in the sphenomandibular ligament seemed to correspond to an intermediate step of development between Meckel's cartilage and the final ligament. Overall, there seemed to be a mini-version of elastic fiber distribution compared to that in adults and a different specific developmental pattern of connective tissues. The latter morphology might be a result of an adaptation to hypoxic conditions during development. PMID:23560235

  3. Distribution of elastic fibers in the head and neck: a histological study using late-stage human fetuses.

    Science.gov (United States)

    Kinoshita, Hideaki; Umezawa, Takashi; Omine, Yuya; Kasahara, Masaaki; Rodríguez-Vázquez, José Francisco; Murakami, Gen; Abe, Shinichi

    2013-03-01

    There is little or no information about the distribution of elastic fibers in the human fetal head. We examined this issue in 15 late-stage fetuses (crown-rump length, 220-320 mm) using aldehyde-fuchsin and elastica-Masson staining, and we used the arterial wall elastic laminae and external ear cartilages as positive staining controls. The posterior pharyngeal wall, as well as the ligaments connecting the laryngeal cartilages, contained abundant elastic fibers. In contrast with the sphenomandibular ligament and the temporomandibular joint disk, in which elastic fibers were partly present, the discomalleolar ligament and the fascial structures around the pterygoid muscles did not have any elastic fibers. In addition, the posterior marginal fascia of the prestyloid space did contain such fibers. Notably, in the middle ear, elastic fibers accumulated along the tendons of the tensor tympani and stapedius muscles and in the joint capsules of the ear ossicle articulations. Elastic fibers were not seen in any other muscle tendons or vertebral facet capsules in the head and neck. Despite being composed of smooth muscle, the orbitalis muscle did not contain any elastic fibers. The elastic fibers in the sphenomandibular ligament seemed to correspond to an intermediate step of development between Meckel's cartilage and the final ligament. Overall, there seemed to be a mini-version of elastic fiber distribution compared to that in adults and a different specific developmental pattern of connective tissues. The latter morphology might be a result of an adaptation to hypoxic conditions during development.

  4. The role of human papilloma virus and p16 in occult primary of the head and neck: a comprehensive review of the literature.

    Science.gov (United States)

    Fotopoulos, George; Pavlidis, Nicholas

    2015-02-01

    Cancer of unknown primary of the head and neck is a challenging entity for the oncologist. The role of human papilloma virus/p16 in carcinogenesis and in prognosis is well established in certain HNSCC especially in that of the oropharynx. In the case of occult primary of the head and neck the role of HPV/p16 positivity is not well defined regarding prognosis and localization of the primary. An independent review of PubMed and ScienceDirect database was performed up to May 2014 using combinations of terms such as "occult primary of the head and neck", "CUP of the head and neck" "metastatic cervical squamous cell carcinoma of unknown primary", "HPV" and "HPV and head and neck cancer". Literature review shows a strong association between HPV/p16 positivity and primary location in the oropharynx in patients with CUP of the head and neck as well as a better clinical outcome. HPV positivity and p16 overexpression could be used as surrogate markers in the search of the primary site of patients with CUP of the head and neck therefore maybe guiding treatment decisions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. The ultimate intrinsic signal-to-noise ratio of loop- and dipole-like current patterns in a realistic human head model.

    Science.gov (United States)

    Pfrommer, Andreas; Henning, Anke

    2018-03-13

    The ultimate intrinsic signal-to-noise ratio (UISNR) represents an upper bound for the achievable SNR of any receive coil. To reach this threshold a complete basis set of equivalent surface currents is required. This study systematically investigated to what extent either loop- or dipole-like current patterns are able to reach the UISNR threshold in a realistic human head model between 1.5 T and 11.7 T. Based on this analysis, we derived guidelines for coil designers to choose the best array element at a given field strength. Moreover, we present ideal current patterns yielding the UISNR in a realistic body model. We distributed generic current patterns on a cylindrical and helmet-shaped surface around a realistic human head model. We excited electromagnetic fields in the human head by using eigenfunctions of the spherical and cylindrical Helmholtz operator. The electromagnetic field problem was solved by a fast volume integral equation solver. At 7 T and above, adding curl-free current patterns to divergence-free current patterns substantially increased the SNR in the human head (locally >20%). This was true for the helmet-shaped and the cylindrical surface. On the cylindrical surface, dipole-like current patterns had high SNR performance in central regions at ultra-high field strength. The UISNR increased superlinearly with B0 in most parts of the cerebrum but only sublinearly in the periphery of the human head. The combination of loop and dipole elements could enhance the SNR performance in the human head at ultra-high field strength. © 2018 International Society for Magnetic Resonance in Medicine.

  6. General equation for the differential pathlength factor of the frontal human head depending on wavelength and age.

    Science.gov (United States)

    Scholkmann, Felix; Wolf, Martin

    2013-10-01

    Continuous-wave near-infrared spectroscopy and near-infrared imaging enable the measurement of relative concentration changes in oxy- and deoxyhemoglobin and thus hemodynamics and oxygenation. The accuracy of determined changes depends mainly on the modeling of the light transport through the probed tissue. Due to the highly scattering nature of tissue, the light path is longer than the source-detector separation (d). This is incorporated in modeling by multiplying d by a differential pathlength factor (DPF) which depends on several factors such as wavelength, age of the subject, and type of tissue. In the present work, we derive a general DPF equation for the frontal human head, incorporating dependency on wavelength and age, based on published data. We validated the equation using different data sets of experimentally determined DPFs from six independent studies.

  7. Measurement of TLD Albedo response on various calibration phantoms

    International Nuclear Information System (INIS)

    Momose, T.; Tsujimura, N.; Shinohara, K.; Ishiguro, H.; Nakamura, T.

    1996-01-01

    The International Commission on Radiation Units and Measurements (ICRU) has recommended that individual dosemeter should be calibrated on a suitable phantom and has pointed out that the calibration factor of a neutron dosemeter is strongly influenced by the the exact size and shape of the body and the phantom to which the dosemeter is attached. As the principle of an albedo type thermoluminescent personal dosemeter (albedo TLD) is essentially based on a detection of scattered and moderated neutron from a human body, the sensitivity of albedo TLD is strongly influenced by the incident neutron energy and the calibration phantom. (1) Therefore for albedo type thermoluminescent personal dosemeter (albedo TLD), the information of neutron albedo response on the calibration phantom is important for appropriate dose estimation. In order to investigate the effect of phantom type on the reading of the albedo TLD, measurement of the TLD energy response and angular response on some typical calibration phantoms was performed using dynamitron accelerator and 252 Cf neutron source. (author)

  8. Heterogeneous Breast Phantom Development for Microwave Imaging Using Regression Models

    Directory of Open Access Journals (Sweden)

    Camerin Hahn

    2012-01-01

    Full Text Available As new algorithms for microwave imaging emerge, it is important to have standard accurate benchmarking tests. Currently, most researchers use homogeneous phantoms for testing new algorithms. These simple structures lack the heterogeneity of the dielectric properties of human tissue and are inadequate for testing these algorithms for medical imaging. To adequately test breast microwave imaging algorithms, the phantom has to resemble different breast tissues physically and in terms of dielectric properties. We propose a systematic approach in designing phantoms that not only have dielectric properties close to breast tissues but also can be easily shaped to realistic physical models. The approach is based on regression model to match phantom's dielectric properties with the breast tissue dielectric properties found in Lazebnik et al. (2007. However, the methodology proposed here can be used to create phantoms for any tissue type as long as ex vivo, in vitro, or in vivo tissue dielectric properties are measured and available. Therefore, using this method, accurate benchmarking phantoms for testing emerging microwave imaging algorithms can be developed.

  9. Influence of variation in eumelanin content on absorbance spectra of liquid skin-like phantoms

    CSIR Research Space (South Africa)

    Smit, Jacoba E

    2011-01-01

    Full Text Available are often always limited. Hence the use of skin-like phantoms. Bashkatov et al. (25) measured the optical properties of gelatin skin-like phantoms prepared from different concentrations of synthetic and natural (from Sepia officianalis) melanin. Fat... emulsions like Intralipid are commonly used to mimic light propagation in turbit media (26) and hence Shimada et al. (27) used similar gelatin and Sepia melanin phantoms and added Intralipid to mimic the scattering properties of human skin. The purpose...

  10. Anthropomorphic Phantoms for Confirmation of Linear Accelerator-Based Small Animal Irradiation.

    Science.gov (United States)

    Perks, Julian R; Lucero, Steven; Monjazeb, Arta M; Li, Jian Jian

    2015-03-01

    Three dimensional (3D) scanning and printing technology is utilized to create phantom models of mice in order to assess the accuracy of ionizing radiation dosing from a clinical, human-based linear accelerator. Phantoms are designed to simulate a range of research questions, including irradiation of lung tumors and primary subcutaneous or orthotopic tumors for immunotherapy experimentation. The phantoms are used to measure the accuracy of dose delivery and then refine it to within 1% of the prescribed dose.

  11. MRI-Based Multiscale Model for Electromagnetic Analysis in the Human Head with Implanted DBS

    Directory of Open Access Journals (Sweden)

    Maria Ida Iacono

    2013-01-01

    Full Text Available Deep brain stimulation (DBS is an established procedure for the treatment of movement and affective disorders. Patients with DBS may benefit from magnetic resonance imaging (MRI to evaluate injuries or comorbidities. However, the MRI radio-frequency (RF energy may cause excessive tissue heating particularly near the electrode. This paper studies how the accuracy of numerical modeling of the RF field inside a DBS patient varies with spatial resolution and corresponding anatomical detail of the volume surrounding the electrodes. A multiscale model (MS was created by an atlas-based segmentation using a 1 mm3 head model (mRes refined in the basal ganglia by a 200 μm2 ex-vivo dataset. Four DBS electrodes targeting the left globus pallidus internus were modeled. Electromagnetic simulations at 128 MHz showed that the peak of the electric field of the MS doubled (18.7 kV/m versus 9.33 kV/m and shifted 6.4 mm compared to the mRes model. Additionally, the MS had a sixfold increase over the mRes model in peak-specific absorption rate (SAR of 43.9 kW/kg versus 7 kW/kg. The results suggest that submillimetric resolution and improved anatomical detail in the model may increase the accuracy of computed electric field and local SAR around the tip of the implant.

  12. A video, text, and speech-driven realistic 3-d virtual head for human-machine interface.

    Science.gov (United States)

    Yu, Jun; Wang, Zeng-Fu

    2015-05-01

    A multiple inputs-driven realistic facial animation system based on 3-D virtual head for human-machine interface is proposed. The system can be driven independently by video, text, and speech, thus can interact with humans through diverse interfaces. The combination of parameterized model and muscular model is used to obtain a tradeoff between computational efficiency and high realism of 3-D facial animation. The online appearance model is used to track 3-D facial motion from video in the framework of particle filtering, and multiple measurements, i.e., pixel color value of input image and Gabor wavelet coefficient of illumination ratio image, are infused to reduce the influence of lighting and person dependence for the construction of online appearance model. The tri-phone model is used to reduce the computational consumption of visual co-articulation in speech synchronized viseme synthesis without sacrificing any performance. The objective and subjective experiments show that the system is suitable for human-machine interaction.

  13. Cocoa and Human Health: From Head to Foot--A Review.

    Science.gov (United States)

    De Araujo, Quintino Reis; Gattward, James Nascimento; Almoosawi, Suzana; Silva, Maria das Graças Conceição Parada Costa; Dantas, Paulo Alfredo De Santana; De Araujo Júnior, Quintino Reis

    2016-01-01

    The cocoa, as part of the wonderful nature, provides the mankind a wide variety of valuable food products and health benefits. The most known and universally relished product derived from this fruit is chocolate, an amazing and unique food for the human nutrition with records of consumption of similar products dating to 1000 years BC. In fact, the cocoa is a complex food that includes over 300 different components. This review is designed to inform scientists, technicians, academicians, farmers, and interested communities of numerous studies that have been conducted worldwide to investigate the properties of various cocoa constituents, their relations to human health, and their potential role in the prevention and treatment of many medical conditions. The general population, for example in Brazil, despite being one of the major producers of cocoa, is poorly informed of the significant and beneficial properties of cocoa. The present review covers important topics linking cocoa to human health and show the state of the art of effect of cocoa in different systems that comprise the human body. The paper is organized based on the main human organ system and includes: cardiovascular/circulatory, neurological/nervous, oral health, endocrine, lymphatic and immunological, respiratory, reproductive, and dermatological systems. Scientific findings tend to confirm the historic designation of cocoa as "food of the Gods."

  14. A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull

    International Nuclear Information System (INIS)

    Wydra, A; Maev, R Gr

    2013-01-01

    In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us. (note)

  15. NURBS-based 3-d anthropomorphic computational phantoms for radiation dosimetry applications

    International Nuclear Information System (INIS)

    Lee, Choonsik; Lodwick, Daniel; Lee, Choonik; Bolch, Wesley E.

    2007-01-01

    Computational anthropomorphic phantoms are computer models used in the evaluation of absorbed dose distributions within the human body. Currently, two classes of the computational phantoms have been developed and widely utilised for dosimetry calculation: (1) stylized (equation-based) and (2) voxel (image-based) phantoms describing human anatomy through the use of mathematical surface equations and 3-D voxel matrices, respectively. However, stylized phantoms have limitations in defining realistic organ contours and positioning as compared to voxel phantoms, which are themselves based on medical images of human subjects. In turn, voxel phantoms that have been developed through medical image segmentation have limitations in describing organs that are presented in low contrast within either magnetic resonance or computed tomography image. The present paper reviews the advantages and disadvantages of these existing classes of computational phantoms and introduces a hybrid approach to a computational phantom construction based on non-uniform rational B-Spline (NURBS) surface animation technology that takes advantage of the most desirable features of the former two phantom types. (authors)

  16. A set of 4D pediatric XCAT reference phantoms for multimodality research

    International Nuclear Information System (INIS)

    Norris, Hannah; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P.; Minhas, Anum; Frush, D.; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

    2014-01-01

    Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

  17. A set of 4D pediatric XCAT reference phantoms for multimodality research

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Hannah, E-mail: Hannah.norris@duke.edu; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Minhas, Anum; Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2014-03-15

    Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

  18. Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis

    International Nuclear Information System (INIS)

    Negus, Ian S.; Holmes, Robin B.; Thorne, Gareth C.; Saunders, Margaret; Jordan, Kirsty C.; Nash, David A.

    2016-01-01

    Purpose: To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. Methods: A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain by adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding 99m Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Results: Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. Conclusions: The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable for

  19. Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis

    Energy Technology Data Exchange (ETDEWEB)

    Negus, Ian S.; Holmes, Robin B.; Thorne, Gareth C.; Saunders, Margaret [Department of Medical Physics and Bioengineering, University Hospitals Bristol NHS Foundation Trust, Bristol BS28HW (United Kingdom); Jordan, Kirsty C. [Department of Biomedical Engineering, University of Strathclyde, Glasgow G11XQ (United Kingdom); Nash, David A. [Department of Medical Physics, Portsmouth Hospitals NHS Trust, Portsmouth PO63LY (United Kingdom)

    2016-09-15

    Purpose: To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. Methods: A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain by adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding {sup 99m}Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Results: Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. Conclusions: The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable

  20. Identification and characterization of cancer stem cells in human head and neck squamous cell carcinoma

    International Nuclear Information System (INIS)

    Han, Jing; Fujisawa, Toshio; Husain, Syed R; Puri, Raj K

    2014-01-01

    Current evidence suggests that initiation, growth, and invasion of cancer are driven by a small population of cancer stem cells (CSC). Previous studies have identified CD44+ cells as cancer stem cells in head and neck squamous cell carcinoma (HNSCC). However, CD44 is widely expressed in most cells in HNSCC tumor samples and several cell lines tested. We previously identified a small population of CD24+/CD44+ cells in HNSCC. In this study, we examined whether this population of cells may represent CSC in HNSCC. CD24+/CD44+ cells from HNSCC cell lines were sorted by flow cytometry, and their phenotype was confirmed by qRT-PCR. Their self-renewal and differentiation properties, clonogenicity in collagen gels, and response to anticancer drugs were tested in vitro. The tumorigenicity potential of CD24+/CD44+ cells was tested in athymic nude mice in vivo. Our results show that CD24+/CD44+ cells possessed stemness characteristics of self-renewal and differentiation. CD24+/CD44+ cells showed higher cell invasion in vitro and made higher number of colonies in collagen gels compared to CD24-/CD44+ HNSCC cells. In addition, the CD24+/CD44+ cells were more chemo-resistant to gemcitabine and cisplatin compared to CD24-/CD44+ cells. In vivo, CD24+/CD44+ cells showed a tendency to generate larger tumors in nude mice compared to CD24-/CD44+ cell population. Our study clearly demonstrates that a distinct small population of CD24+/CD44+ cells is present in HNSCC that shows stem cell-like properties. This distinct small population of cells should be further characterized and may provide an opportunity to target HNSCC CSC for therapy

  1. A feasiblity study of an ultrasonic test phantom arm

    Science.gov (United States)

    Schneider, Philip

    This thesis is a feasibility study for the creation of a test phantom that replicates the physiological features, from an acoustic and mechanical standpoint, of that of a human arm. Physiological feature set includes; Heart, Arteries, Veins, Bone, Muscle, Fat, Skin, and Dermotographic Features (finger prints). Mechanical Aspects include, vascular compression and distention, elasticity of tissue layers, mechanics of human heart. The end goal of which to have a working understanding of each component in order to create a controllable, real time, physiologically accurate, test phantom for a wide range of ultrasonic based applications. These applications can range from devices like wearable technologies to medical training, to biometric "Liveness" detection methods. The proposed phantom would allow for a number of natural bodily functions to be measured including but not limited to vascular mapping, blood pressure, heart rate, subdermal imaging, and general ultrasonic imaging.

  2. Human papillomavirus and its influence on head and neck cancer predisposition

    Directory of Open Access Journals (Sweden)

    Kamil H. Nelke

    2013-07-01

    Full Text Available Human papillomavirus (HPV is a virus often infecting humans. It is often present on skin or mucousmembranes. These diverse DNA viruses are often linked to many various benign and malignant neoplasticlesions. Over 40 types of HPV are transmitted through sexual contact and infect the anogenital regionwhich might be secondly transmitted to the oral mucous. Over 150 HPV viruses are defined according tothe invaded site. Oral papillomas are marked with numbers 6, 7, 11, 16 and 32. Squamous cell papillomais often found in laryngeal epithelial tumor associated with HPV-6 and HPV-11 and also HPV-16 in oralsquamous cell carcinoma (OSCC. In the last 15 years OSCC has become more common in children andyoung adults. The role of HPV virus causing oral squamous cell carcinomas is more often realized, butpeople’s lack of knowledge and risky sexual behavior is still the main factor in growing HPV infections.

  3. Focusing the photon dose in a head phantom

    International Nuclear Information System (INIS)

    Arkuszewski, J.

    1997-01-01

    The 30 keV photons stereotactic focusing is being examined for two kinds of collimated sources and it has been found less advantageous as compared to the gamma-knife MeV range. (author) 2 figs., 2 refs

  4. Human BK Polyomavirus—The Potential for Head and Neck Malignancy and Disease

    Directory of Open Access Journals (Sweden)

    Raquel Burger-Calderon

    2015-07-01

    Full Text Available Members of the human Polyomaviridae family are ubiquitous and pathogenic among immune-compromised individuals. While only Merkel cell polyomavirus (MCPyV has conclusively been linked to human cancer, all members of the polyomavirus (PyV family encode the oncoprotein T antigen and may be potentially carcinogenic. Studies focusing on PyV pathogenesis in humans have become more abundant as the number of PyV family members and the list of associated diseases has expanded. BK polyomavirus (BKPyV in particular has emerged as a new opportunistic pathogen among HIV positive individuals, carrying harmful implications. Increasing evidence links BKPyV to HIV-associated salivary gland disease (HIVSGD. HIVSGD is associated with elevated risk of lymphoma formation and its prevalence has increased among HIV/AIDS patients. Determining the relationship between BKPyV, disease and tumorigenesis among immunosuppressed individuals is necessary and will allow for expanding effective anti-viral treatment and prevention options in the future.

  5. Natural and Human-Induced Variations in Accretion of the Roanoke Bay-head Delta

    Science.gov (United States)

    Jalowska, A.; McKee, B. A.; Rodriguez, A. B.

    2014-12-01

    Bay-head deltas (BHD), along with their adjacent floodplains serve as storage sites for lithogenic and organic material on millennial time scales and are biogeochemically active sites on daily to decadal time scales, contributing to global nutrient and carbon cycles. BHD host unique, highly diverse ecosystems such as the pristine swamp forest and hardwood bottomlands, of the Lower Roanoke River, NC. The global value of ecosystem services provided by wetlands within natural BHD is 2.5 to 2.8 mln 2007$/km2/year. BHD are very sensitive to changes in sedimentation and to changes in the rate of sea-level rise. Core descriptions, 14C geo-chronologies and grain-size analyses show that the Roanoke BHD in North Carolina, USA experienced two episodes of retreat in late Holocene. The first event occurred around ca 3500 cal. yr. BC and is recognized as a prominent flooding surface separating the delta plain environment, below, from interdistributary bay, above. Across the flooding surface rates of sediment accumulation decreased from 1.8-3.3 mm/year to 0.5-0.6 mm/year. That change was associated with increased sediment accommodation. Sedimentation rates were keeping up with the low rates of sea-level rise until 1600-1700 AD. During that time, the delta started to rapidly accrete and the interdistributary bay was buried with delta plain and prodelta sediment. This occurred in response to the low rates of sea-level rise at that time (-0.1 to 0.47 mm/year) and the release of large quantities of sediments associated with the initiation of agriculture by European settlers in the drainage basin. The second episode of retreat was initiated during the 19th century when the rate of sea-level rose to 2.1 mm/year. During that time, agricultural practices improved, decreasing the amount of sediments delivered to the mouth of the Roanoke River. Under these conditions, the delta started backstepping. Analyses of historical maps, aerial photography, and side-scan sonar data show that between

  6. Effects of human head hair on performance and thermoregulatory responses during 10-km outdoor running in healthy men

    Directory of Open Access Journals (Sweden)

    Angelo Ruediger Pisani Martini

    2016-05-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p155   The aim of the present study was to evaluate the effects of human head hair on performance and thermoregulatory responses during 10-km outdoor running in healthy men. Twelve healthy males (29.5 ± 3.7 years, 174.9 ± 4.3 cm, 72.7 ± 3.2 kg and VO2max 44.6 ± 3.4 ml.kg-1.min-1 participated in two self-paced outdoor 10-km running trials separated by 7 days: 1 HAIR, subjects ran with their natural head hair; 2 NOHAIR, subjects ran after their hair had been totally shaved. Average running velocity was calculated from each 2-km running time. Rectal temperature, heart rate and physiological strain index were measured before and after the 10-km runs and at the end of each 2 km. The rate of heat storage was measured every 2 km. The environmental stress (WBGT was measured every 10 min. The running velocity (10.9 ± 1 and 10.9 ± 1.1 km.h-1, heart rate (183 ± 10 and 180 ± 12 bpm, rectal temperature (38.82 ± 0.29 and 38.81 ± 0.49oC, physiological strain index (9 ± 1 and 9 ± 1, or heat storage rate (71.9 ± 64.1 and 80.7 ± 56.7 W.m-1 did not differ between the HAIR and NOHAIR conditions, respectively (p>0.05. There was no difference in WBGT between the HAIR and NOHAIR conditions (24.0 ± 1.4 and 23.2 ± 1.5ºC, respectively; p=0.10. The results suggest that shaved head hair does not alter running velocity or thermoregulatory responses during 10-km running under the sun.

  7. Knowledge of human papillomavirus and its association with head and neck benign and malignant lesions in a group of dental patients in pakistan.

    Science.gov (United States)

    Gichki, Abdul Samad; Buajeeb, Waranun; Doungudomdacha, Sombhun; Khovidhunkit, Siribang-On Pibooniyom

    2015-01-01

    Human papillomaviruses (HPVs) remain a serious world health problem due to their association with cervical and head and neck cancers. While over 100 HPV types have been identified, only a few subtypes are associated with malignancies. HPV 16 and 18 are the most prevalent oncogenic types in head and neck cancers. Although it has been proven that some subsets of benign and malignant head and neck lesions are associated with HPV, the general population have very little awareness and knowledge of their association with HPV. Therefore, the purpose of this study was to determine the knowledge of HPV and its links with head and neck benign and malignant lesions in a group of Pakistani dental patients who attended the Dental Department of the Sandeman provincial hospital in Quetta, Pakistan. One hundred and ninety-two patients were recruited and requested to answer a questionnaire. It was revealed that there was a low level of knowledge about HPV and its association with head and neck benign and malignant lesions among the participants. This result suggested that more education regarding the relationship of HPV in inducing head and neck benign and malignant lesions is required in this group of patients.

  8. Construction of Chinese reference female phantom

    International Nuclear Information System (INIS)

    Sheng Yinxiangzi; Liu Lixing; Xia Xiaobin

    2013-01-01

    In this study, a Voxel-based Chinese Reference female Phantom (VCRP-woman) is developed from an individual female phantom which was based on high resolution cross-sectional color photographs. An in-house C ++ program was developed to adjust the phantom. Finally, a reference female phantom with have the same height, weighte and similar organs masses with the Chinese reference adult female data. The adjusted phantom is then imported to MCNPX to calculate the organs absorbed dose and effective dose conversion coefficients. Results are compared between VCRP-woman and the ICRP adult reference female phantom. (authors)

  9. The Relationship Between Human Papillomavirus Status and Other Molecular Prognostic Markers in Head and Neck Squamous Cell Carcinomas

    International Nuclear Information System (INIS)

    Kong, Christina S.; Narasimhan, Balasubramanian; Cao Hongbin; Kwok, Shirley; Erickson, Julianna P.; Koong, Albert; Pourmand, Nader; Le, Quynh-Thu

    2009-01-01

    Purpose: To evaluate the relationship between human papillomavirus (HPV) status and known prognostic makers for head and neck cancers including tumor hypoxia, epidermal growth factor receptor (EGFR) expression and intratumoral T-cell levels and to determine the prognostic impact of these markers by HPV status. Methods and Materials: HPV status in 82 evaluable head and neck squamous cell carcinomas patients was determined by pyrosequencing and related to p16 INK4a staining and treatment outcomes. It was correlated with tumor hypoxia (tumor pO 2 and carbonic anhydrase [CAIX] staining), EGFR status, and intratumoral lymphocyte expression (CD3 staining). Results: Forty-four percent of evaluable tumors had strong HPV signal by pyrosequencing. There was a significant relationship between strong HPV signal and p16 INK4a staining as well as oropharynx location. The strong HPV signal group fared significantly better than others, both in time to progression (TTP, p = 0.008) and overall survival (OS, p = 0.004) for all patients and for the oropharyngeal subset. Positive p16 INK4a staining was associated with better TTP (p = 0.014) and OS (p = 0.00002). There was no relationship between HPV status and tumor pO 2 or CAIX staining. However, HPV status correlated inversely with EGFR reactivity (p = 0.0006) and directly with CD3(+) T-lymphocyte level (p = 0.03). Whereas CAIX and EGFR overexpression were negative prognostic factors regardless of HPV status, CD3(+) T-cell levels was prognostic only in HPV(-) tumors. Conclusion: HPV status was a prognostic factor for progression and survival. It correlated inversely with EGFR expression and directly with T-cell infiltration. The prognostic effect of CAIX and EGFR expression was not influenced by HPV status, whereas intratumoral T-cell levels was significant only for HPV(-) tumors.

  10. Modelling and validation of diffuse reflectance of the adult human head for fNIRS: scalp sub-layers definition

    Science.gov (United States)

    Herrera-Vega, Javier; Montero-Hernández, Samuel; Tachtsidis, Ilias; Treviño-Palacios, Carlos G.; Orihuela-Espina, Felipe

    2017-11-01

    Accurate estimation of brain haemodynamics parameters such as cerebral blood flow and volume as well as oxygen consumption i.e. metabolic rate of oxygen, with funcional near infrared spectroscopy (fNIRS) requires precise characterization of light propagation through head tissues. An anatomically realistic forward model of the human adult head with unprecedented detailed specification of the 5 scalp sublayers to account for blood irrigation in the connective tissue layer is introduced. The full model consists of 9 layers, accounts for optical properties ranging from 750nm to 950nm and has a voxel size of 0.5mm. The whole model is validated comparing the predicted remitted spectra, using Monte Carlo simulations of radiation propagation with 108 photons, against continuous wave (CW) broadband fNIRS experimental data. As the true oxy- and deoxy-hemoglobin concentrations during acquisition are unknown, a genetic algorithm searched for the vector of parameters that generates a modelled spectrum that optimally fits the experimental spectrum. Differences between experimental and model predicted spectra was quantified using the Root mean square error (RMSE). RMSE was 0.071 +/- 0.004, 0.108 +/- 0.018 and 0.235+/-0.015 at 1, 2 and 3cm interoptode distance respectively. The parameter vector of absolute concentrations of haemoglobin species in scalp and cortex retrieved with the genetic algorithm was within histologically plausible ranges. The new model capability to estimate the contribution of the scalp blood flow shall permit incorporating this information to the regularization of the inverse problem for a cleaner reconstruction of brain hemodynamics.

  11. (−-Gossypol Inhibits Growth and Promotes Apoptosis of Human Head and Neck Squamous Cell Carcinoma In Vivo

    Directory of Open Access Journals (Sweden)

    Keith G. Wolter

    2006-03-01

    Full Text Available Resistance to chemotherapy is a common problem encountered in the treatment of head and neck squamous cell carcinoma (HNSCC. Chemoresistant HNSCC tumors frequently overexpress antiapoptotic proteins, such as BCI-xL. (−-Gossypol, the negative enantiomer of a cottonseed polyphenol, binds to BCI-xL and was recently been shown to inhibit HNSCC proliferation in vitro. In this study, we assessed the in vivo efficacy of (−-gossypol in an orthotopic xenograff model of HNSCC, using two human HNSCC cell lines with high BCI-xL expression levels. Both produced tumors in a murine floor-of-mouth model that mimics human HNSCC, exhibiting growth and invasion into adjacent tissues. Mice were randomized into three groups: vehicle control and two daily intraperitoneal (−-gossypol treatment groups (5 and 15 mg/kg. Tumors were measured twice weekly. In the control group, tumors grew progressively, whereas in (−-gossypol treatment groups, tumor growth was significantly suppressed. The mitotic rate in tumors from (−-gossypol-treated animals was significantly lower than that in controls, and an increase in the percentage of apoptotic cells was observed in treated tumors versus controls. Residual tumors remained growth-suppressed for 2 weeks after cessation of (−-gossypol treatment. Our results demonstrate that (−-gossypol can inhibit tumor growth in an orthotopic model of aggressive HNSCC.

  12. Human Papillomavirus Type 16 E6 and E7 Oncoproteins Act Synergistically to Cause Head and Neck Cancer in Mice

    Science.gov (United States)

    Jabbar, Sean; Strati, Katerina; Shin, Myeong Kyun; Pitot, Henry C.; Lambert, Paul F.

    2010-01-01

    High-risk human papillomaviruses (HPVs) contribute to cervical and other anogenital cancers, and they are also linked etiologically to a subset of head and neck squamous cell carcinomas (HNSCC). We previously established a model for HPV-associated HNSCC in which we treated transgenic mice expressing the papillomaviral oncoproteins with the chemical carcinogen 4-nitroquinoline-1-oxide (4-NQO). We found that the HPV-16 E7 oncoprotein was highly potent in causing HNSCC, and its dominance masked any potential oncogenic contribution of E6, a second papillomaviral oncoprotein commonly expressed in human cancers. In the current study, we shortened the duration of treatment with 4-NQO to reduce the incidence of cancers and discovered a striking synergy between E6 and E7 in causing HNSCC. Comparing the oncogenic properties of wild-type versus mutant E6 genes in this model for HNSCC uncovered a role for some but not other cellular targets of E6 previously shown to contribute to cervical cancer. PMID:20797753

  13. Quantitative analysis of three-dimensional fibrillar collagen microstructure within the normal, aged and glaucomatous human optic nerve head.

    Science.gov (United States)

    Jones, H J; Girard, M J; White, N; Fautsch, M P; Morgan, J E; Ethier, C R; Albon, J

    2015-05-06

    The aim of this study was to quantify connective tissue fibre orientation and alignment in young, old and glaucomatous human optic nerve heads (ONH) to understand ONH microstructure and predisposition to glaucomatous optic neuropathy. Transverse (seven healthy, three glaucomatous) and longitudinal (14 healthy) human ONH cryosections were imaged by both second harmonic generation microscopy and small angle light scattering (SALS) in order to quantify preferred fibre orientation (PFO) and degree of fibre alignment (DOFA). DOFA was highest within the peripapillary sclera (ppsclera), with relatively low values in the lamina cribrosa (LC). Elderly ppsclera DOFA was higher than that in young ppsclera (p < 0.00007), and generally higher than in glaucoma ppsclera. In all LCs, a majority of fibres had preferential orientation horizontally across the nasal-temporal axis. In all glaucomatous LCs, PFO was significantly different from controls in a minimum of seven out of 12 LC regions (p < 0.05). Additionally, higher fibre alignment was observed in the glaucomatous inferior-temporal LC (p < 0.017). The differences between young and elderly ONH fibre alignment within regions suggest that age-related microstructural changes occur within the structure. The additional differences in fibre alignment observed within the glaucomatous LC may reflect an inherent susceptibility to glaucomatous optic neuropathy, or may be a consequence of ONH remodelling and/or collapse.