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Sample records for heating phantom results

  1. Non-invasive ultrasound-based temperature imaging for monitoring radiofrequency heating-phantom results

    International Nuclear Information System (INIS)

    Daniels, M J; Varghese, T; Madsen, E L; Zagzebski, J A

    2007-01-01

    Minimally invasive therapies (such as radiofrequency ablation) are becoming more commonly used in the United States for the treatment of hepatocellular carcinomas and liver metastases. Unfortunately, these procedures suffer from high recurrence rates of hepatocellular carcinoma (∼34-55%) or metastases following ablation therapy. The ability to perform real-time temperature imaging while a patient is undergoing radiofrequency ablation could provide a significant reduction in these recurrence rates. In this paper, we demonstrate the feasibility of ultrasound-based temperature imaging on a tissue-mimicking phantom undergoing radiofrequency heating. Ultrasound echo signals undergo time shifts with increasing temperature, which are tracked using 2D correlation-based speckle tracking methods. Time shifts or displacements in the echo signal are accumulated, and the gradient of these time shifts are related to changes in the temperature of the tissue-mimicking phantom material using a calibration curve generated from experimental data. A tissue-mimicking phantom was developed that can undergo repeated radiofrequency heating procedures. Both sound speed and thermal expansion changes of the tissue-mimicking material were measured experimentally and utilized to generate the calibration curve relating temperature to the displacement gradient. Temperature maps were obtained, and specific regions-of-interest on the temperature maps were compared to invasive temperatures obtained using fiber-optic temperature probes at the same location. Temperature elevation during a radiofrequency ablation procedure on the phantom was successfully tracked to within ±0.5 0 C

  2. Regional heating patterns of RF hyperthermia applicators in phantoms

    International Nuclear Information System (INIS)

    Kantor, G.; Ruggera, P.S.; Samulski, T.V.

    1984-01-01

    An elliptical phantom (20 cm by 30 cm cross-section and 40 cm long) with a 1 cm fat layer filled with muscle material was used to compare the induced heating patterns of the NCDRH helical coil, a Henry Medical Magnetrode coil, both with a diameter of 35.6 cm, and the BSD Annular Phased Array System (APAS). Temperature profiles were taken in the midplane cross-sectional slice along the major and minor axes of the phantom. These profiles were measured with a Vitek thermistor probe and the associated specific absorption rates (SAR) were determined from this data. SAR curves for each applicator were obtained along the major and minor axes of the phantom. The depths of heating of the Magnetrode applicator are considerably smaller than those for the helical applicator. Heating patterns for the APAS can be highly variable and asymmetric depending on the frequency of operation and the location of the phantom within the APAS aperture. While the APAS requires a water bolus for good coupling, the NCDRH and Magnetrode coils need only to be air coupled for good phantom coupling. Both the helical applicator and APAS can provide significant heating in the central region of the phantom. However, the heating of the helical coil does not critically depend on the phantom loading

  3. 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

  4. Investigation of heat distribution during magnetic heating treatment using a polyurethane–ferrofluid phantom-model

    International Nuclear Information System (INIS)

    Henrich, F.; Rahn, H.; Odenbach, S.

    2014-01-01

    Magnetic heating treatment can be used as an adjuvant treatment for cancer therapy. In this therapy, magnetic nanoparticles are enriched inside the tumour and exposed to an alternating magnetic field. Due to magnetic losses the temperature in the tumour rises. The resulting temperature profile inside the tumour is useful for the therapeutic success. In this context heat transfer between tissue with nanoparticles and tissue without nanoparticles is a highly important feature which is actually not understood in detail. In order to investigate this, a phantom has been created which can be used to measure the temperature profile around a region enriched with magnetic nanoparticles. This phantom is composed of a material, which has similar thermal conductivity as human tissue. A tempered water bath surrounds the phantom to establish a constant surrounding temperature simulating the heat sink provided by the human body in a real therapeutic application. It has been found that even at a low concentration of magnetic nanoparticles around 13 mg/ml, sufficient heating of the enriched region can be achieved. Moreover it has been observed that the temperature drops rapidly in the material surrounding the enriched region. Corresponding numerical investigations provide a basis for future recalculations of the temperature inside the tumour using temperature data obtained in the surrounding tissue. - Highlights: • The temperature profile by magnetic hyperthermia was examined. • A model was built to get a deeper understanding of the temperature profile. • The temperature profile of the model inside magnetic fields was measured. • Based on the model a simulation of the temperature profile was performed. • The simulated temperature profile agreed well with the measured profile

  5. Magnetic navigation in a coronary phantom: experimental results.

    Science.gov (United States)

    García-García, Héctor M; Tsuchida, Keiichi; Meulenbrug, Hans; Ong, Andrew T L; Van der Giessen, Willem J; Serruys, Patrick W

    2005-11-01

    The objective was to investigate the efficacy of a magnetic navigation system (MNS) in a coronary phantom. The number of coronary interventional procedures performed is steadily increasing with the availability of new devices to treat more complex lesions. Vessel tortuosity remains an important limiting factor in percutaneous coronary intervention. The MNS can orient the tip of magnetized wire. The coronary phantom is a representation of the coronary tree. Two operators using both a magnetic wire and a standard wire, measured the procedural time (PT), the fluoroscopic time (FT) and the radiation exposure/area product (DAP) required to navigate through to fourteen segments. Ten wire advancements were performed per segment. In all but two segments, the PT was significantly longer using magnetic navigation than using manual navigation. The median FT in the left main artery (LMA) - first septal segment was 7 seconds vs. 18 seconds, with magnetic and manual navigation respectively, (p=0.05); in the LMA - obtuse marginal segment the median FT was 15 seconds with magnetic navigation vs. 29.5 seconds with manual navigation, (p=0.01); in the segment from proximal right coronary artery (RCA1) to the acute marginal branch, the median FT was 8 seconds with magnetic vs. 11 seconds with manual navigation, (p=0.05); and in the RCA1 -posterior descending segment the median FT was 9.5 seconds with magnetic vs. 15 seconds with manual navigation, (p=0.006). The MNS facilitates wire access to distal segments in a coronary phantom, with a reduction in FT and radiation exposure using magnetic navigation in tortuous segments.

  6. Methods for characterizing convective cryoprobe heat transfer in ultrasound gel phantoms.

    Science.gov (United States)

    Etheridge, Michael L; Choi, Jeunghwan; Ramadhyani, Satish; Bischof, John C

    2013-02-01

    While cryosurgery has proven capable in treating of a variety of conditions, it has met with some resistance among physicians, in part due to shortcomings in the ability to predict treatment outcomes. Here we attempt to address several key issues related to predictive modeling by demonstrating methods for accurately characterizing heat transfer from cryoprobes, report temperature dependent thermal properties for ultrasound gel (a convenient tissue phantom) down to cryogenic temperatures, and demonstrate the ability of convective exchange heat transfer boundary conditions to accurately describe freezing in the case of single and multiple interacting cryoprobe(s). Temperature dependent changes in the specific heat and thermal conductivity for ultrasound gel are reported down to -150 °C for the first time here and these data were used to accurately describe freezing in ultrasound gel in subsequent modeling. Freezing around a single and two interacting cryoprobe(s) was characterized in the ultrasound gel phantom by mapping the temperature in and around the "iceball" with carefully placed thermocouple arrays. These experimental data were fit with finite-element modeling in COMSOL Multiphysics, which was used to investigate the sensitivity and effectiveness of convective boundary conditions in describing heat transfer from the cryoprobes. Heat transfer at the probe tip was described in terms of a convective coefficient and the cryogen temperature. While model accuracy depended strongly on spatial (i.e., along the exchange surface) variation in the convective coefficient, it was much less sensitive to spatial and transient variations in the cryogen temperature parameter. The optimized fit, convective exchange conditions for the single-probe case also provided close agreement with the experimental data for the case of two interacting cryoprobes, suggesting that this basic characterization and modeling approach can be extended to accurately describe more complicated

  7. Development of a QA Phantom for online image registration and resultant couch shifts

    International Nuclear Information System (INIS)

    Arumugam, S.; Jameson, M.G.; Holloway, L.C.

    2010-01-01

    Full text: Purpose Recently our centre purchased an Elekta-Synergy accelerator with kV-CBCT and a hexapod couch attachment. This system allows six degrees of freedom for couch lOp shifts, based on registration of on line imaging. We designed and built a phantom in our centre to test the accuracy and precision of this system. The goal of this project was to investigate the accuracy and practical utilisation of this phantom. Method The phantom was constructed from perspex sheets and high density dental putty (Fig. I). Five high density regions (three small regions to simulate prostate seeds and two larger regions to simulate boney anatomy) were incorporated to test the manual and automatic registrations within the software. The phantom was utilised to test the accuracy and precision of repositioning with the hexapod couch and imaging system. To achieve this, the phantom was placed on the couch at known orientations and the shifts were quantified using the registration of verification and reference image data sets. True shifts and those predicted by the software were compared. Results The geometrical accuracy of the phantom was verified with measurements of the CT scan to be with I mm of the intended geometry. The image registration and resultant couch shifts were found to be accurate within I mm and 0.5 degrees. The phantom was found to be practical and easy to use. Conclusion The presented phantom provides a less expensive and effective alternative to commercially available systems for verifying imaging registration and corresponding six degrees of freedom couch shifts. (author)

  8. SU-G-TeP2-12: IROCHouston and MDAPL SRS Anthropomorphic Phantom Results

    International Nuclear Information System (INIS)

    Molineu, A; Kry, S; Alvarez, P; Hernandez, N; Nguyen, T; Followill, D

    2016-01-01

    Purpose: To report the results of SRS phantom irradiations Methods: Anthropomorphic SRS head phantoms were sent to institutions participating in NCI sponsored SRS clinical trials and institutions interested in verifying SRS treatment delivery. The phantom shell was purchased from Phantom Laboratory and altered to house dosimetry and imaging inserts. The imaging insert has 1.9 cm diameter spherical target. The dosimetry insert holds two TLD capsules and radiochromic film in the coronal and sagittal planes through the center of the target. Institutions were asked to image, plan and treat the phantom as they would an SRS patient. GammaKnife, CyberKnife and c-arm accelerator institutions were asked to cover the target with 15 Gy, 20 Gy and 25 Gy, respectively. Following these guidelines and typical planning protocols for these three types of machines gives roughly 30 Gy to the center of the target for all units. Submission of the DICOM digital data set was required for analysis. Criteria of 5% for TLD results and 85% of pixels passing 5%/3mm gamma analysis were applied beginning in 2013. Results: The phantom was analyzed 269 times between the beginning of 2013 to present. The pass rate is 81%. Nineteen of the irradiation results failed only the TLD criteria, 19 failed only the film criteria and 12 failed both. Irradiations included 32 CyberKnife 23 GammaKnife, 3 TomoTherapy and 211 c-arm units. Planning systems included Eclipse, Ergo, GammaPlan, Hi-Art, iPlan, Monaco, MultiPlan, Pinnacle, RayStation, XiO and XKnife. Irradiations that were not accompanied with DICOM data were not included in this analysis. Conclusion: The phantom is a valuable end-to-end test used to independently verify the accuracy of SRS treatment delivery. This investigation was supported by IROC grant CA180803 awarded by the NCI.

  9. TU-G-BRD-05: Results From Multi-Institutional Measurements with An Anthropomorphic Spine Phantom

    International Nuclear Information System (INIS)

    Molineu, A; Hernandez, N; Alvarez, P; Followill, D

    2015-01-01

    Purpose: To analyze the results from an anthropomorphic spine phantom used for credentialing institutions for National Cancer Institute (NCI) sponsored clinical trial. Methods: An anthropomorphic phantom that contains left and right lungs, a heart, an esophagus, spinal cord, bony material and a PTV was sent to institutions wishing to be credentialed for NCI trials. The PTV holds 4 TLD and radiochromic film in the axial and sagittal planes. The heart holds one TLD. Institutions created IMRT plans to cover ≥90% of the PTV with 6 Gy and limit the cord dose to <0.35cc receiving 3.75 Gy and <1.2cc receiving 2.63 Gy. They were instructed to treat the phantom as they would a patient, including making plan specific IMRT/SBRT QA measurements before treatment. The TLD results in the PTV were required to be within ±7% of the plan dose. A gamma calculation was performed using the film results and the submitted DICOM plan. ≥85% of the analyzed region was required to pass a 5%/3 mm criteria. Results: 176 institutions irradiated the spine phantom for a total of 255 results. The pass rate was 73% (187 irradiations) overall. 44 irradiations failed only the gamma criteria, 2 failed only the dose criteria and 22 failed both. The most used planning systems were Eclipse (116) and Pinnacle (52) and they had pass rates of 76% and 71%, respectively. The AAA algorithm had a pass rate of 77% while superposition type algorithms had a 71% pass rate. The average TLD measurement to institution calculation ratio was 0.99 (0.04 std dev.). The average percent pixels passing the gamma criteria for films was 89% (12% std dev.) Conclusion: Results show that this phantom is an important part of credentialing and that we have room for improvement in IMRT/SBRT spine treatments. This work was supported by PHS CA180803 and CA037422 awarded by NCI, DHHS

  10. MO-E-17A-12: Direct Realization of the CT Dose to Phantom: Energy to Heat Conversion in Polyethylene Using Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Chen-Mayer, H; Tosh, R [NIST, Gaithersburg, MD (United States)

    2014-06-15

    Purpose: To develop a primary reference standard for absorbed dose to phantom for medical CT dosimetry. CT dosimetry relies on the implementation of the CTDI standard based on air kerma. We are taking a step toward an absorbed dose to water standard by first investigating the dose in a solid phantom. By directly measuring the heat converted from the incident radiation, the absorbed dose in the phantom at a point can be assessed with primary methods without relying on indirect conversions. Methods: The calorimeter contains two small thermistors embedded in a removable PE “core” inserted into the cylindrical HDPE phantom. A core made with polystyrene (PS) was also tested because of its purportedly negligible heat defect. Measurements were made using the two cores and with a calibrated ionization chamber in a CT beam. The air chamber values were converted to the dose to medium using appropriate stopping-power ratios from the literature, and then compared to the thermal data. Results: The PS core data yielded a dose of 1.3 times (4-run average, 3% std. dev.) higher than the converted chamber value, whereas the PE core data were inexplicably higher. The possible systematic errors include 1) excess heat from the thermistors, 2) in PE the exothermic chemical reactions, 3) uncertainties of the specific heat capacities of the materials, 4) thermal drift, and 5) theoretical conversion of chamber values. Monte Carlo simulations and finite element heat transfer calculations were performed to address some of these issues. The general validity was assessed in a 6 MV photon beam with an entirely different calibration scheme. Conclusion: This study demonstrates the feasibility but also revealed the difficulty in developing a new primary reference standard for absorbed dose to material for CT. Additional experimental and theoretical work is planned to achieve our goal.

  11. Investigation of partial volume effect in different PET/CT systems: a comparison of results using the madeira phantom and the NEMA NU-2 2001 phantom

    International Nuclear Information System (INIS)

    Chipiga, L.; Sydoff, M.; Zvonova, I.; Bernhardsson, C.

    2016-01-01

    Positron emission tomography combined with computed tomography (PET/CT) is a quantitative technique used for diagnosing various diseases and for monitoring treatment response for different types of tumours. However, the accuracy of the data is limited by the spatial resolution of the system. In addition, the so-called partial volume effect (PVE) causes a blurring of image structures, which in turn may cause an underestimation of activity of a structure with high-activity content. In this study, a new phantom, MADEIRA (Minimising Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations) for activity quantification in PET and single photon emission computed tomography (SPECT) was used to investigate the influence on the PVE by lesion size and tumour-to-background activity concentration ratio (TBR) in four different PET/CT systems. These measurements were compared with data from measurements with the NEMA NU-2 2001 phantom. The results with the MADEIRA phantom showed that the activity concentration (AC) values were closest to the true values at low ratios of TBR (<10) and reduced to 50 % of the actual AC values at high TBR (30-35). For all scanners, recovery of true values became closer to 1 with an increasing diameter of the lesion. The MADEIRA phantom showed good agreement with the results obtained from measurements with the NEMA NU-2 2001 phantom but allows for a wider range of possibilities in measuring image quality parameters. (authors)

  12. Initial quality performance results using a phantom to simulate chest computed radiography

    Directory of Open Access Journals (Sweden)

    Muhogora Wilbroad

    2011-01-01

    Full Text Available The aim of this study was to develop a homemade phantom for quantitative quality control in chest computed radiography (CR. The phantom was constructed from copper, aluminium, and polymenthylmethacrylate (PMMA plates as well as Styrofoam materials. Depending on combinations, the literature suggests that these materials can simulate the attenuation and scattering characteristics of lung, heart, and mediastinum. The lung, heart, and mediastinum regions were simulated by 10 mm x 10 mm x 0.5 mm, 10 mm x 10 mm x 0.5 mm and 10 mm x 10 mm x 1 mm copper plates, respectively. A test object of 100 mm x 100 mm and 0.2 mm thick copper was positioned to each region for CNR measurements. The phantom was exposed to x-rays generated by different tube potentials that covered settings in clinical use: 110-120 kVp (HVL=4.26-4.66 mm Al at a source image distance (SID of 180 cm. An approach similar to the recommended method in digital mammography was applied to determine the CNR values of phantom images produced by a Kodak CR 850A system with post-processing turned off. Subjective contrast-detail studies were also carried out by using images of Leeds TOR CDR test object acquired under similar exposure conditions as during CNR measurements. For clinical kVp conditions relevant to chest radiography, the CNR was highest over 90-100 kVp range. The CNR data correlated with the results of contrast detail observations. The values of clinical tube potentials at which CNR is the highest are regarded to be optimal kVp settings. The simplicity in phantom construction can offer easy implementation of related quality control program.

  13. Compound analysis of gallstones using dual energy computed tomography-Results in a phantom model

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Ralf W., E-mail: ralfwbauer@aol.co [Department of Diagnostic and Interventional Radiology, Clinic of the Goethe University Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt (Germany); Schulz, Julian R., E-mail: julian.schulz@t-online.d [Department of Diagnostic and Interventional Radiology, Clinic of the Goethe University Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt (Germany); Zedler, Barbara, E-mail: zedler@em.uni-frankfurt.d [Department of Forensic Medicine, Clinic of the Goethe University Frankfurt, Kennedyallee 104, 60596 Frankfurt (Germany); Graf, Thomas G., E-mail: thomas.gt.graf@siemens.co [Siemens AG Healthcare Sector, Computed Tomography, Physics and Applications, Siemensstrasse 1, 91313 Forchheim (Germany); Vogl, Thomas J., E-mail: t.vogl@em.uni-frankfurt.d [Department of Diagnostic and Interventional Radiology, Clinic of the Goethe University Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt (Germany)

    2010-07-15

    Purpose: The potential of dual energy computed tomography (DECT) for the analysis of gallstone compounds was investigated. The main goal was to find parameters, that can reliably define high percentage (>70%) cholesterol stones without calcium components. Materials and methods: 35 gallstones were analyzed with DECT using a phantom model. Stone samples were put into specimen containers filled with formalin. Containers were put into a water-filled cylindrical acrylic glass phantom. DECT scans were performed using a tube voltage/current of 140 kV/83 mAs (tube A) and 80 kV/340 mAs (tube B). ROI-measurements to determine CT attenuation of each sector of the stones that had different appearance on the CT images were performed. Finally, semi-quantitative infrared spectroscopy (FTIR) of these sectors was performed for chemical analysis. Results: ROI-measurements were performed in 45 different sectors in 35 gallstones. Sectors containing >70% of cholesterol and no calcium component (n = 20) on FTIR could be identified with 95% sensitivity and 100% specificity on DECT. These sectors showed typical attenuation of -8 {+-} 4 HU at 80 kV and +22 {+-} 3 HU at 140 kV. Even the presence of a small calcium component (<10%) hindered the reliable identification of cholesterol components as such. Conclusion: Dual energy CT allows for reliable identification of gallstones containing a high percentage of cholesterol and no calcium component in this pre-clinical phantom model. Results from in vivo or anthropomorphic phantom trials will have to confirm these results. This may enable the identification of patients eligible for non-surgical treatment options in the future.

  14. Compound analysis of gallstones using dual energy computed tomography-Results in a phantom model

    International Nuclear Information System (INIS)

    Bauer, Ralf W.; Schulz, Julian R.; Zedler, Barbara; Graf, Thomas G.; Vogl, Thomas J.

    2010-01-01

    Purpose: The potential of dual energy computed tomography (DECT) for the analysis of gallstone compounds was investigated. The main goal was to find parameters, that can reliably define high percentage (>70%) cholesterol stones without calcium components. Materials and methods: 35 gallstones were analyzed with DECT using a phantom model. Stone samples were put into specimen containers filled with formalin. Containers were put into a water-filled cylindrical acrylic glass phantom. DECT scans were performed using a tube voltage/current of 140 kV/83 mAs (tube A) and 80 kV/340 mAs (tube B). ROI-measurements to determine CT attenuation of each sector of the stones that had different appearance on the CT images were performed. Finally, semi-quantitative infrared spectroscopy (FTIR) of these sectors was performed for chemical analysis. Results: ROI-measurements were performed in 45 different sectors in 35 gallstones. Sectors containing >70% of cholesterol and no calcium component (n = 20) on FTIR could be identified with 95% sensitivity and 100% specificity on DECT. These sectors showed typical attenuation of -8 ± 4 HU at 80 kV and +22 ± 3 HU at 140 kV. Even the presence of a small calcium component (<10%) hindered the reliable identification of cholesterol components as such. Conclusion: Dual energy CT allows for reliable identification of gallstones containing a high percentage of cholesterol and no calcium component in this pre-clinical phantom model. Results from in vivo or anthropomorphic phantom trials will have to confirm these results. This may enable the identification of patients eligible for non-surgical treatment options in the future.

  15. 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

  16. Optimisation need of dental radiodiagnostic procedures: results of effective dose evaluation from Rando phantom measurements

    International Nuclear Information System (INIS)

    Borio, R.; Chiocchini, S.; Cicioni, R.; Degli Esposti, P.; Rongoni, A.; Sabatini, P.; Saetta, D.M.S.; Regi, L.; Caprino, G.

    1994-01-01

    Radiological examinations of different types are needed in dental practice both to make a correct diagnosis and to carry out an adequate therapy. Particularly in orthodentic practices, because of the youth of the majority of the patients, an assessment of the detriment to health (through the effective dose equivalent) caused by medical diagnostic exposure to ionising radiation is needed to make decisions about the optimisation of dental radiodiagnostic procedures. Experimental data from measurements on a Rando phantom were collected for the radiological examinations required for dental and for orthodontic practices (with and without protective apron and collar). The results show the effectiveness of the leaded apron and collar in all the examinations carried out, particularly in reducing thyroid dose. (author)

  17. 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. ...

  18. SU-F-207-05: Excess Heat Corrections in a Prototype Calorimeter for Direct Realization of CT Absorbed Dose to Phantom

    International Nuclear Information System (INIS)

    Chen-Mayer, H; Tosh, R

    2015-01-01

    Purpose: To reconcile air kerma and calorimetry measurements in a prototype calorimeter for obtaining absorbed dose in diagnostic CT beams. While corrections for thermal artifacts are routine and generally small in calorimetry of radiotherapy beams, large differences in relative stopping powers of calorimeter materials at the lower energies typical of CT beams greatly magnify their effects. Work-to-date on the problem attempts to reconcile laboratory measurements with modeling output from Monte Carlo and finite-element analysis of heat transfer. Methods: Small thermistor beads were embedded in a polystyrene (PS) core element of 1 cm diameter, which was inserted into a cylindrical HDPE phantom of 30 cm diameter and subjected to radiation in a diagnostic CT x-ray imaging system. Resistance changes in the thermistors due to radiation heating were monitored via lock-in amplifier. Multiple 3-second exposures were recorded at 8 different dose-rates from the CT system, and least-squares fits to experimental data were compared to an expected thermal response obtained by finite-element analysis incorporating source terms based on semi-empirical modeling and Monte Carlo simulation. Results: Experimental waveforms exhibited large thermal artifacts with fast time constants, associated with excess heat in wires and glass, and smaller steps attributable to radiation heating of the core material. Preliminary finite-element analysis follows the transient component of the signal qualitatively, but predicts a slower decay of temperature spikes. This was supplemented by non-linear least-squares fits incorporating semi-empirical formulae for heat transfer, which were used to obtain dose-to-PS in reasonable agreement with the output of Monte Carlo calculations that converts air kerma to absorbed dose. Conclusion: Discrepancies between the finite-element analysis and our experimental data testify to the very significant heat transfer correction required for absorbed dose calorimetry of

  19. SU-F-207-05: Excess Heat Corrections in a Prototype Calorimeter for Direct Realization of CT Absorbed Dose to Phantom

    Energy Technology Data Exchange (ETDEWEB)

    Chen-Mayer, H; Tosh, R [NIST, Gaithersburg, MD (United States)

    2015-06-15

    Purpose: To reconcile air kerma and calorimetry measurements in a prototype calorimeter for obtaining absorbed dose in diagnostic CT beams. While corrections for thermal artifacts are routine and generally small in calorimetry of radiotherapy beams, large differences in relative stopping powers of calorimeter materials at the lower energies typical of CT beams greatly magnify their effects. Work-to-date on the problem attempts to reconcile laboratory measurements with modeling output from Monte Carlo and finite-element analysis of heat transfer. Methods: Small thermistor beads were embedded in a polystyrene (PS) core element of 1 cm diameter, which was inserted into a cylindrical HDPE phantom of 30 cm diameter and subjected to radiation in a diagnostic CT x-ray imaging system. Resistance changes in the thermistors due to radiation heating were monitored via lock-in amplifier. Multiple 3-second exposures were recorded at 8 different dose-rates from the CT system, and least-squares fits to experimental data were compared to an expected thermal response obtained by finite-element analysis incorporating source terms based on semi-empirical modeling and Monte Carlo simulation. Results: Experimental waveforms exhibited large thermal artifacts with fast time constants, associated with excess heat in wires and glass, and smaller steps attributable to radiation heating of the core material. Preliminary finite-element analysis follows the transient component of the signal qualitatively, but predicts a slower decay of temperature spikes. This was supplemented by non-linear least-squares fits incorporating semi-empirical formulae for heat transfer, which were used to obtain dose-to-PS in reasonable agreement with the output of Monte Carlo calculations that converts air kerma to absorbed dose. Conclusion: Discrepancies between the finite-element analysis and our experimental data testify to the very significant heat transfer correction required for absorbed dose calorimetry of

  20. Results From the Imaging and Radiation Oncology Core Houston's Anthropomorphic Phantoms Used for Proton Therapy Clinical Trial Credentialing

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Paige A., E-mail: pataylor@mdanderson.org; Kry, Stephen F.; Alvarez, Paola; Keith, Tyler; Lujano, Carrie; Hernandez, Nadia; Followill, David S.

    2016-05-01

    Purpose: The purpose of this study was to summarize the findings of anthropomorphic proton phantom irradiations analyzed by the Imaging and Radiation Oncology Core Houston QA Center (IROC Houston). Methods and Materials: A total of 103 phantoms were irradiated by proton therapy centers participating in clinical trials. The anthropomorphic phantoms simulated heterogeneous anatomy of a head, liver, lung, prostate, and spine. Treatment plans included those for scattered, uniform scanning, and pencil beam scanning beam delivery modalities using 5 different treatment planning systems. For every phantom irradiation, point doses and planar doses were measured using thermoluminescent dosimeters (TLD) and film, respectively. Differences between measured and planned doses were studied as a function of phantom, beam delivery modality, motion, repeat attempt, treatment planning system, and date of irradiation. Results: The phantom pass rate (overall, 79%) was high for simple phantoms and lower for phantoms that introduced higher levels of difficulty, such as motion, multiple targets, or increased heterogeneity. All treatment planning systems overestimated dose to the target, compared to TLD measurements. Errors in range calculation resulted in several failed phantoms. There was no correlation between treatment planning system and pass rate. The pass rates for each individual phantom are not improving over time, but when individual institutions received feedback about failed phantom irradiations, pass rates did improve. Conclusions: The proton phantom pass rates are not as high as desired and emphasize potential deficiencies in proton therapy planning and/or delivery. There are many areas for improvement with the proton phantom irradiations, such as treatment planning system dose agreement, range calculations, accounting for motion, and irradiation of multiple targets.

  1. The impact of audio-visual biofeedback on 4D PET images: Results of a phantom study

    Science.gov (United States)

    Yang, Jaewon; Yamamoto, Tokihiro; Cho, Byungchul; Seo, Youngho; Keall, Paul J.

    2012-01-01

    Purpose: Irregular breathing causes motion blurring artifacts in 4D PET images. Audiovisual (AV) biofeedback has been demonstrated to improve breathing regularity. To investigate the hypothesis that, compared with free breathing, motion blurring artifacts are reduced with AV biofeedback, the authors performed the first experimental phantom-based quantification of the impact of AV biofeedback on 4D PET image quality. Methods: The authors acquired 4D PET dynamic phantom images with AV biofeedback and free breathing by moving a phantom programmed with AV biofeedback trained and free breathing respiratory traces of ten healthy subjects. The authors also acquired stationary phantom images for reference. The phantom was cylindrical with six hollow sphere targets (10, 13, 17, 22, 28, and 37 mm in diameter). The authors quantified motion blurring using the target diameter, Dice coefficient and recovery coefficient (RC) metrics to estimate the effect of motion. Results: The average increase in target diameter for AV biofeedback was 0.6±1.6mm(4.7±13%), which was significantly (pbiofeedback was 0.90±0.07, which was significantly (pbiofeedback were consistently higher than those for free breathing and comparable to those for stationary targets. However, for RCs the impact of target sizes was more dominant than that of motion. In addition, the authors observed large variations in the results with respect to target sizes, subject traces and respiratory bins due to partial volume effects and respiratory motion irregularity. Conclusions: The results indicate that AV biofeedback can significantly reduce motion blurring artifacts and may facilitate improved identification and localization of lung tumors in 4D PET images. The results justify proceeding with clinical studies to quantify the impact of AV biofeedback on 4D PET image quality and tumor detectability. PMID:22320815

  2. 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)

  3. Virtual endoscopy of the small bowel: phantom study and preliminary clinical results

    International Nuclear Information System (INIS)

    Rogalla, P.; Werner-Rustner, M.; Meiri, N.; Hamm, B.; Huitema, A.; van Est, A.

    1998-01-01

    The purpose of this study was to determine the optimal scanning technique for lesion detection in a small bowel phantom and to evaluate the virtual endoscopy (VE) technique in patients. A small bowel phantom with a fold thickness of 7 mm and length of 115 cm was prepared with nine round lesions (3 x 1 mm, 2 x 2 mm, 2 x 3 mm, 2 x 4 mm). Spiral CT parameters were 7/7/4, 3/5/2, 3/5/1, 1.5/3/1 (slice thickness/table feed/reconstruction interval). VE was done using volume rendering technique with 1 cm distance between images and 120 viewing angle. Two masked readers were asked to determine the number and location of the lesions. Seven patients underwent an abdominal CT during one breathhold after placement of a duodenal tube and filling of the small bowel with methyl cellulose contrast solution. VE images were compared with the axial slices with respect to detectability of pathology. With the 7/7/4 protocol only the 4-mm lesions were visualised with fuzzy contours. The 3/5/2 protocol showed both 4-mm lesions, one 3-mm lesion and one false positive lesion. The 3/5/1 protocol showed both 4-mm and both 3-mm (one uncertain) lesions with improved sharpness, and no false positive lesions. One 2-mm and one 1-mm lesion were additionally seen with the 1.5/3/1 protocol. Path definition was difficult in sharp turns or kinks in the lumen. In all patients, no difference was found between VE and axial slices for bowel pathology; however, axial slices showed 'outside' information that was not included in VE. We conclude that the 3/5/2 protocol may be regarded as an optimal compromise between lesion detection, coverage during one breathhold, and number of reconstructed images in patients; round lesions of 4 mm in diameter can be detected with high certainty. (orig.)

  4. Semi-robotic 6 degree of freedom positioning for intracranial high precision radiotherapy; first phantom and clinical results

    Directory of Open Access Journals (Sweden)

    Flentje Michael

    2010-05-01

    Full Text Available Abstract Background To introduce a novel method of patient positioning for high precision intracranial radiotherapy. Methods An infrared(IR-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP and connected to the table via a 6 degree-of-freedom(DoF mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT is performed. A robotic 6 DoF treatment couch (HexaPOD™ then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within ± 2 mm and ± 2° of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction. The preclinical feasibility and attainable repositioning accuracy of this method was evaluated on a phantom and human volunteers as was the clinical efficacy on 7 pilot study patients. Results Phantom and volunteer manual IR-based prepositioning to within ± 2 mm and ± 2° in 6DoF was possible within a mean(± SD of 90 ± 31 and 56 ± 22 seconds respectively. Mean phantom translational and rotational precision after 6 DoF corrections by the HexaPOD was 0.2 ± 0.2 mm and 0.7 ± 0.8° respectively. For the actual patient collective, the mean 3D vector for inter-treatment repositioning accuracy (n = 102 was 1.6 ± 0.8 mm while intra-fraction movement (n = 110 was 0.6 ± 0.4 mm. Conclusions This novel semi-automatic 6DoF IR-based system has been shown to compare favourably with existing non-invasive intracranial repeat fixation systems with respect to handling, reproducibility and, more importantly, intra-fraction rigidity. Some advantages are full cranial positioning flexibility for single and fractionated IGRT treatments and possibly increased patient

  5. Aortic stentgraft movement detection using digital roentgen stereophotogrammetric analysis on plane film radiographs - initial results of a phantom study

    International Nuclear Information System (INIS)

    Georg, C.; Welker, V.; Eidam, H.; Alfke, H.

    2005-01-01

    Purpose: To evaluate the feasibility of aortic stentgraft micromovement detection using digital roentgen stereophotogrammetric analysis on plane film radiographs. Material and Methods: An aortic stentgraft used for demonstration purposes was marked with 10 tantalum markers of 0.8 mm in diameter. The stentgraft was placed on a Plexiglas phantom with 5 tantalum markers of 1 mm in diameter simulating a fixed segment needed for mathematical analysis. In a subsequent step, the stentgraft was placed onto an orthopaedic spine model to simulate in vivo conditions in a next step.Two radiographs taken simultaneously from different angles were used for simulating different stentgraft movement, e.g. translation, angulation, aortic pulsation and migration in the spine model. Movement of the stentgraft markers was analysed using a commercially available digital RSA setup (UmRSA registered 4.1, RSA Biomedical, Umea, Sweden). Results: Our study shows the feasibility of measuring aortic stentgraft movement and changes in stentgraft shape in the submillimeter range using digital roentgen stereophotogrammetric analysis. Translation along the 3 cardinal axes, change in stentgraft shape, simulation of aortic pulsation and simulation of in vivo conditions could be described precisely. Conclusion: Aortic stentgraft movement detection using digital roentgen stereophotogrammetric analysis on plane film radiographs is a very promising, precise method. (orig.)

  6. 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...

  7. Monte Carlo electron-photon transport using GPUs as an accelerator: Results for a water-aluminum-water phantom

    Energy Technology Data Exchange (ETDEWEB)

    Su, L.; Du, X.; Liu, T.; Xu, X. G. [Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2013-07-01

    An electron-photon coupled Monte Carlo code ARCHER - Accelerated Radiation-transport Computations in Heterogeneous Environments - is being developed at Rensselaer Polytechnic Institute as a software test bed for emerging heterogeneous high performance computers that utilize accelerators such as GPUs. In this paper, the preliminary results of code development and testing are presented. The electron transport in media was modeled using the class-II condensed history method. The electron energy considered ranges from a few hundred keV to 30 MeV. Moller scattering and bremsstrahlung processes above a preset energy were explicitly modeled. Energy loss below that threshold was accounted for using the Continuously Slowing Down Approximation (CSDA). Photon transport was dealt with using the delta tracking method. Photoelectric effect, Compton scattering and pair production were modeled. Voxelised geometry was supported. A serial ARHCHER-CPU was first written in C++. The code was then ported to the GPU platform using CUDA C. The hardware involved a desktop PC with an Intel Xeon X5660 CPU and six NVIDIA Tesla M2090 GPUs. ARHCHER was tested for a case of 20 MeV electron beam incident perpendicularly on a water-aluminum-water phantom. The depth and lateral dose profiles were found to agree with results obtained from well tested MC codes. Using six GPU cards, 6x10{sup 6} histories of electrons were simulated within 2 seconds. In comparison, the same case running the EGSnrc and MCNPX codes required 1645 seconds and 9213 seconds, respectively, on a CPU with a single core used. (authors)

  8. Automatic exposure control to reduce the dose in subsecond multislice spiral CT: phantom measurements and clinical results

    International Nuclear Information System (INIS)

    Greess, H.; Bautz, W.; Baum, U.; Wolf, H.; Suess, C.; Kalender, W.A.

    2004-01-01

    Purpose: To investigate the potential of dose reduction in multislice spiral CT (MSCT) with automatic exposure control. Materials and Methods: The study was performed on a Sensation 4 multislice scanner. This prototype implementation analyzed the distribution of the attenuation along the z-axis in the lateral and sagittal directions of the digital radiogram. Depending on this distribution of the attenuation, the tube current (mA) is defined for every tube rotation. In addition, the tube current was modulated during each tube rotation. First, a three step oval water phantom was measured to evaluate the potential of this method with respect to dose reduction and image quality. In a patient study (n=26), four different scan regions (shoulder, thorax, abdomen, pelvis) were examined and dose (mAs) and image quality evaluated in comparison to examinations with a standard protocol for these regions in adults and a weight-adjusted standard protocol in children. The image quality was classified in consensus as good, sufficient and poor image quality. Results: By adapting and modulating the tube current, we substantially reduced the variation of noise in one spiral scan and in one scan region of our patient collective. The dose (average mAs) was reduced by 31% to 66% in children (mean 44%) and between 35% and 64% in adults (mean 53%), depending on the scan region. The image quality was substantially improved in regions with high attenuation and did not suffer in low attenuation regions. Conclusion: The dose can be reduced substantially by an automatic exposure control including angular tube current modulation with the same or improved image quality. (orig.) [de

  9. [Heat stroke and burns resulting from use of sauna

    DEFF Research Database (Denmark)

    Runitz, K.; Jensen, T.H.

    2009-01-01

    We describe a case of severe heat stroke resulting from exposure to extreme heat in a sauna for an unknown period of time. The patient sustained 20% 2nd degree burns. On arrival at the emergency department, the patient's temperature was 40.5 degrees C. At the critical care unit, the patient devel...... developed severe multi-organ failure and critical polyneuropathy. Severe heat stroke is a rare diagnosis in Denmark. The treatment is symptomatic and the prognosis is grave, especially in combination with severe burns Udgivelsesdato: 2009/1/26......We describe a case of severe heat stroke resulting from exposure to extreme heat in a sauna for an unknown period of time. The patient sustained 20% 2nd degree burns. On arrival at the emergency department, the patient's temperature was 40.5 degrees C. At the critical care unit, the patient...

  10. Electromagnetic tracking for CT-guided spine interventions: phantom, ex-vivo and in-vivo results

    International Nuclear Information System (INIS)

    Bruners, Philipp; Penzkofer, Tobias; Nagel, Markus; Elfring, Robert; Schmitz-Rode, Thomas; Gronloh, Nina; Guenther, Rolf W.; Mahnken, Andreas H.

    2009-01-01

    An electromagnetic-based tracking and navigation system was evaluated for interventional radiology. The electromagnetic tracking system (CAPPA IRAD EMT, CASinnovations, Erlangen, Germany) was used for real-time monitoring of punctures of the lumbar facet joints and intervertebral disks in a spine phantom, three pig cadavers and three anaesthesized pigs. Therefore, pre-interventional computed tomography (CT) datasets were transferred to the navigation system and puncture trajectories were planned. A coaxial needle was advanced along the trajectories while the position of the needle tip was monitored in real time. After puncture tracts were marked with pieces of wire another CT examination was performed and distances between wires and anatomical targets were measured. Performing punctures of the facet joints mean needle positioning errors were 0.4 ± 0.8 mm in the spine phantom, 2.8 ± 2.1 mm ex vivo and 3.0 ± 2.0 mm in vivo with mean length of the puncture tract of 54.0 ± 10.4 mm (phantom), 51.6 ± 12.6 mm (ex vivo) and 50.9 ± 17.6 mm (in vivo). At first attempt, intervertebral discs were successfully punctured in 15/15 in the phantom study, in 12/15 in the ex-vivo study and 14/15 in the in-vivo study, respectively. Immobilization of the patient and optimal positioning of the field generator are essential to achieve a high accuracy of needle placement in a clinical CT setting. (orig.)

  11. Effects of Hot Streak and Phantom Cooling on Heat Transfer in a Cooled Turbine Stage Including Particulate Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bons, Jeffrey [The Ohio State Univ., Columbus, OH (United States); Ameri, Ali [The Ohio State Univ., Columbus, OH (United States)

    2016-01-08

    The objective of this research effort was to develop a validated computational modeling capability for the characterization of the effects of hot streaks and particulate deposition on the heat load of modern gas turbines. This was accomplished with a multi-faceted approach including analytical, experimental, and computational components. A 1-year no cost extension request was approved for this effort, so the total duration was 4 years. The research effort succeeded in its ultimate objective by leveraging extensive experimental deposition studies complemented by computational modeling. Experiments were conducted with hot streaks, vane cooling, and combinations of hot streaks with vane cooling. These studies contributed to a significant body of corporate knowledge of deposition, in combination with particle rebound and deposition studies funded by other agencies, to provide suitable conditions for the development of a new model. The model includes the following physical phenomena: elastic deformation, plastic deformation, adhesion, and shear removal. It also incorporates material property sensitivity to temperature and tangential-normal velocity rebound cross-dependencies observed in experiments. The model is well-suited for incorporation in CFD simulations of complex gas turbine flows due to its algebraic (explicit) formulation. This report contains model predictions compared to coefficient of restitution data available in the open literature as well as deposition results from two different high temperature turbine deposition facilities. While the model comparisons with experiments are in many cases promising, several key aspects of particle deposition remain elusive. The simple phenomenological nature of the model allows for parametric dependencies to be evaluated in a straightforward manner. This effort also included the first-ever full turbine stage deposition model published in the open literature. The simulations included hot streaks and simulated vane cooling

  12. Quality control within the multicentre perfusion CT study of primary colorectal cancer (PROSPeCT): results of an iodine density phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Maria; Honey, Ian [Trust, Medical Physics Department, Guy' s and St. Thomas' NHS Foundation, London (United Kingdom); Goh, Vicky [King' s College London, St Thomas' Hospital, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Beggs, Shaun [Bradford Teaching Hospitals NHS Foundation Trust, Radiation Physics Services, Bradford (United Kingdom); Bridges, Andrew; Wayte, Sarah [Radiology Physics University Hospitals Coventry and Warwickshire NHS Trust, Coventry (United Kingdom); Clewer, Philip [Medical Physics Department, University Hospital Southampton NHS Foundation Trust, Southampton (United Kingdom); Davis, Anne [Portsmouth Hospitals NHS Trust, Medical Physics Department, Portsmouth (United Kingdom); Foy, Trevelyan [Royal Cornwall Hospital NHS Trust, Medical Physics Department, Truro (United Kingdom); Fuller, Karen [Sheffield Teaching Hospitals NHS Foundation Trust, Medical Physics Department, Sheffield (United Kingdom); George, Jennifer [University Hospital of North Staffordshire NHS Trust, Medical Physics Department, Stoke-on-Trent (United Kingdom); Higginson, Antony [Portsmouth Hospitals NHS Trust, Department of Radiology, Portsmouth (United Kingdom); Iball, Gareth [Leeds Teaching Hospitals NHS Trust, Department of Medical Physics and Engineering, Leeds (United Kingdom); Mutch, Steve [Oxford University Hospitals NHS Trust, Radiation Physics and Protection Department, Oxford (United Kingdom); Neil, Shellagh; Sutton, David [NHS Tayside, Medical Physics Department, Dundee, Scotland (United Kingdom); Rivett, Cat [Plymouth Hospitals NHS Trust, Clinical and Radiation Physics, Plymouth (United Kingdom); Slater, Andrew [Oxford University Hospitals NHS Trust, Department of Radiology, Oxford (United Kingdom); Weir, Nick [Queen' s Medical Research Institute, Clinical Research Imaging Centre, Edinburgh, Scotland (United Kingdom); Collaboration: on behalf of the PROSPeCT Investigators

    2014-09-15

    To assess the cross-centre consistency of iodine enhancement, contrast-to-noise ratio and radiation dose in a multicentre perfusion CT trial of colorectal cancer. A cylindrical water phantom containing different iodine inserts was examined on seven CT models in 13 hospitals. The relationship between CT number (Hounsfield units, HU) and iodine concentration (milligrams per millilitre) was established and contrast-to-noise ratios (CNRs) calculated. Radiation doses (CTDI{sub vol}, DLP) were compared across all sites. There was a linear relationship between CT number and iodine density. Iodine enhancement varied by a factor of at most 1.10, and image noise by at most 1.5 across the study sites. At an iodine concentration of 1 mg ml{sup -1} and 100 kV, CNRs ranged from 3.6 to 4.8 in the 220-mm phantom and from 1.4 to 1.9 in the 300-mm phantom. Doses varied by a factor of at most 2.4, but remained within study dose constraints. Iterative reconstruction algorithms did not alter iodine enhancement but resulted in reduced image noise by a factor of at most 2.2, allowing a potential dose decrease of at most 80 % compared to filtered back projection (FBP). Quality control of CT performance across centres indicates that CNR values remain relatively consistent across all sites, giving acceptable image quality within the agreed dose constraints. (orig.)

  13. Quality control within the multicentre perfusion CT study of primary colorectal cancer (PROSPeCT): results of an iodine density phantom study

    International Nuclear Information System (INIS)

    Lewis, Maria; Honey, Ian; Goh, Vicky; Beggs, Shaun; Bridges, Andrew; Wayte, Sarah; Clewer, Philip; Davis, Anne; Foy, Trevelyan; Fuller, Karen; George, Jennifer; Higginson, Antony; Iball, Gareth; Mutch, Steve; Neil, Shellagh; Sutton, David; Rivett, Cat; Slater, Andrew; Weir, Nick

    2014-01-01

    To assess the cross-centre consistency of iodine enhancement, contrast-to-noise ratio and radiation dose in a multicentre perfusion CT trial of colorectal cancer. A cylindrical water phantom containing different iodine inserts was examined on seven CT models in 13 hospitals. The relationship between CT number (Hounsfield units, HU) and iodine concentration (milligrams per millilitre) was established and contrast-to-noise ratios (CNRs) calculated. Radiation doses (CTDI vol , DLP) were compared across all sites. There was a linear relationship between CT number and iodine density. Iodine enhancement varied by a factor of at most 1.10, and image noise by at most 1.5 across the study sites. At an iodine concentration of 1 mg ml -1 and 100 kV, CNRs ranged from 3.6 to 4.8 in the 220-mm phantom and from 1.4 to 1.9 in the 300-mm phantom. Doses varied by a factor of at most 2.4, but remained within study dose constraints. Iterative reconstruction algorithms did not alter iodine enhancement but resulted in reduced image noise by a factor of at most 2.2, allowing a potential dose decrease of at most 80 % compared to filtered back projection (FBP). Quality control of CT performance across centres indicates that CNR values remain relatively consistent across all sites, giving acceptable image quality within the agreed dose constraints. (orig.)

  14. Design, manufacture, and evaluation of an anthropomorphic pelvic phantom purpose-built for radiotherapy dosimetric intercomparison

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, K. M.; Ebert, M. A.; Kron, T.; Howlett, S. J.; Cornes, D.; Hamilton, C. S.; Denham, J. W. [Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales 2298, Australia and School of Physics, University of Newcastle, New South Wales 2308 (Australia); Department of Radiation Oncology, Sir Charles Gairdner Hospital, Western Australia, Australia and School of Physics, University of Western Australia, Western Australia 6009 (Australia); Department of Physical Sciences, Peter MacCallum Cancer Centre, Victoria 8006 (Australia); Australiasian College of Physical Scientists and Engineers in Medicine, Sydney, New South Wales 2020 (Australia); Trans-Tasman Radiation Oncology Group, Calvary Mater Newcastle, New South Wales 2298 (Australia); Heidelberg Repatriation Hospital, Victoria 3081 (Australia); Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales 2298, Australia and School of Medicine and Population Health, University of Newcastle, New South Wales 2308 (Australia)

    2011-10-15

    Purpose: An anthropomorphic pelvic phantom was designed and constructed to meet specific criteria for multicenter radiotherapy dosimetric intercomparison. Methods: Three dimensional external and organ outlines were generated from a computed tomography image set of a male pelvis, forming the basis of design for an anatomically realistic phantom. Clinically relevant points of interest were selected throughout the dataset where point-dose values could be measured with thermoluminescence dosimeters and a small-volume ionization chamber. Following testing, three materials were selected and the phantom was manufactured using modern prototyping techniques into five separate coronal slices. Time lines and resource requirements for the phantom design and manufacture were recorded. The ability of the phantom to mimic the entire treatment chain was tested. Results: The phantom CT images indicated that organ densities and geometries were comparable to those of the original patient. The phantom proved simple to load for dosimetry and rapid to assemble. Due to heat release during manufacture, small air gaps and density heterogeneities were present throughout the phantom. The overall cost for production of the prototype phantom was comparable to other commercial anthropomorphic phantoms. The phantom was shown to be suitable for use as a ''patient'' to mimic the entire treatment chain for typical external beam radiotherapy for prostate and rectal cancer. Conclusions: The phantom constructed for the present study incorporates all characteristics necessary for accurate Level III intercomparison studies. Following use in an extensive Level III dosimetric comparison over a large time scale and geographic area, the phantom retained mechanical stability and did not show signs of radiation-induced degradation.

  15. Space Launch System Base Heating Test: Experimental Operations & Results

    Science.gov (United States)

    Dufrene, Aaron; Mehta, Manish; MacLean, Matthew; Seaford, Mark; Holden, Michael

    2016-01-01

    NASA's Space Launch System (SLS) uses four clustered liquid rocket engines along with two solid rocket boosters. The interaction between all six rocket exhaust plumes will produce a complex and severe thermal environment in the base of the vehicle. This work focuses on a recent 2% scale, hot-fire SLS base heating test. These base heating tests are short-duration tests executed with chamber pressures near the full-scale values with gaseous hydrogen/oxygen engines and RSRMV analogous solid propellant motors. The LENS II shock tunnel/Ludwieg tube tunnel was used at or near flight duplicated conditions up to Mach 5. Model development was based on the Space Shuttle base heating tests with several improvements including doubling of the maximum chamber pressures and duplication of freestream conditions. Test methodology and conditions are presented, and base heating results from 76 runs are reported in non-dimensional form. Regions of high heating are identified and comparisons of various configuration and conditions are highlighted. Base pressure and radiometer results are also reported.

  16. Semi-robotic 6 degree of freedom positioning for intracranial high precision radiotherapy; first phantom and clinical results

    International Nuclear Information System (INIS)

    Wilbert, Jürgen; Guckenberger, Matthias; Polat, Bülent; Sauer, Otto; Vogele, Michael; Flentje, Michael; Sweeney, Reinhart A

    2010-01-01

    To introduce a novel method of patient positioning for high precision intracranial radiotherapy. An infrared(IR)-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP) and connected to the table via a 6 degree-of-freedom(DoF) mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT) is performed. A robotic 6 DoF treatment couch (HexaPOD™) then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within ± 2 mm and ± 2° of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction. The preclinical feasibility and attainable repositioning accuracy of this method was evaluated on a phantom and human volunteers as was the clinical efficacy on 7 pilot study patients. Phantom and volunteer manual IR-based prepositioning to within ± 2 mm and ± 2° in 6DoF was possible within a mean(± SD) of 90 ± 31 and 56 ± 22 seconds respectively. Mean phantom translational and rotational precision after 6 DoF corrections by the HexaPOD was 0.2 ± 0.2 mm and 0.7 ± 0.8° respectively. For the actual patient collective, the mean 3D vector for inter-treatment repositioning accuracy (n = 102) was 1.6 ± 0.8 mm while intra-fraction movement (n = 110) was 0.6 ± 0.4 mm. This novel semi-automatic 6DoF IR-based system has been shown to compare favourably with existing non-invasive intracranial repeat fixation systems with respect to handling, reproducibility and, more importantly, intra-fraction rigidity. Some advantages are full cranial positioning flexibility for single and fractionated IGRT treatments and possibly increased patient comfort

  17. 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)

  18. Preliminary results of statistical dynamic experiments on a heat exchanger

    International Nuclear Information System (INIS)

    Corran, E.R.; Cummins, J.D.

    1962-10-01

    The inherent noise signals present in a heat exchanger have been recorded and analysed in order to determine some of the statistical dynamic characteristics of the heat exchanger. These preliminary results show that the primary side temperature frequency response may be determined by analysing the inherent noise. The secondary side temperature frequency response and cross coupled temperature frequency responses between primary and secondary are poorly determined because of the presence of a non-stationary noise source in the secondary circuit of this heat exchanger. This may be overcome by correlating the dependent variables with an externally applied noise signal. Some preliminary experiments with an externally applied random telegraph type of signal are reported. (author)

  19. 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

  20. Solar systems and heat pumps in operation in Carinthia: results 1994 - 1997

    International Nuclear Information System (INIS)

    Faninger, G.

    1998-04-01

    Solar systems and heat pumps in operation in Carinthia: results 1994 - 1997. Test results from solar systems for swimming pool heating, hot water preparation and space heating as well as heat pumps for hot water preparation, space heating and heat recovery will be reported and assessed collectively. (author)

  1. Use of scatter correction in quantitative I-123 MIBG scintigraphy for differentiating patients with Parkinsonism: Results from Phantom experiment and clinical study

    International Nuclear Information System (INIS)

    Bai, J.; Hashimoto, J.; Suzuki, T.; Nakahara, T.; Kubo, A.; Ohira, M.; Takao, M.; Ogawa, K.

    2007-01-01

    The aims of this study were to elucidate the feasibility of scatter correction in improving the quantitative accuracy of the Heart-to-Mediastinum (H/M) ratio in I-123 MIBG imaging and to clarify whether the H/M ratio calculated from the scatter corrected image improves the accuracy of differentiating patients with Parkinsonism from other neurological disorders. The H/M ratio was calculated using the counts from planar images processed with and without scatter correction in the phantom and on patients. The triple energy window (TEW) method was used for scatter correction. Fifty five patients were enrolled in the clinical study. The Receiver Operating Characteristic (ROC) Curve analysis was used to evaluate diagnostic performance. The H/M ratio was found to be increased after scatter correction in the phantom simulating normal cardiac uptake, while no changes were observed in the phantom simulating no uptake. It was observed that scatter correction stabilized the H/M ratio by eliminating the influence of scatter photons originating from the liver, especially in the condition of no cardiac uptake. Similarly, scatter correction increased the H/M ratio in conditions other than Parkinson's disease but did not show any change in Parkinson's disease itself to widen the differences in the H/M ratios between the two groups. The overall power of the test did not show any significant improvement after scatter correction in differentiating patients with Parkinsonism. Based on the results of this study it has been concluded that scatter correction improves the quantitative accuracy of H/M ratio in MIBG imaging, but it does not offer any significant incremental diagnostic value over conventional imaging (without scatter correction). Nevertheless it is felt that the scatter correction technique deserves special consideration in order to make the test more robust and obtain stable H/M ratios. (author)

  2. KamLAND results and the radiogenic terrestrial heat

    International Nuclear Information System (INIS)

    Fiorentini, Gianni; Lissia, Marcello; Mantovani, Fabio; Ricci, Barbara

    2005-01-01

    We find that recent results from the KamLAND Collaboration on geologically produced antineutrinos, N(U+Th)=28 -15 +16 events, correspond to a radiogenic heat production from uranium and thorium decay chains H(U+Th)=38 -33 +35 TW. The 99% confidence limit on the geo-neutrino signal translates into the upper bound H(U+Th) 13 C(α,n) 16 O cross section. The result, N(U+Th)=31 -13 +14 , corroborates the evidence (∼2.5σ) for geo-neutrinos in KamLAND data

  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. Contrast-enhanced voiding urosonography phantom study: intravenous iodinated and gadolinium-based contrast agents may cause false-negative results in assessment of vesicoureteral reflux in children

    International Nuclear Information System (INIS)

    Veldhoen, Simon; Sauer, Alexander; Gassenmaier, Tobias; Petritsch, Bernhard; Herz, Stefan; Blanke, Philipp; Bley, Thorsten A.; Wirth, Clemens; Derlin, Thorsten

    2015-01-01

    Contrast-enhanced voiding urosonography (ce-VUS) is commonly requested simultaneously to other diagnostic imaging necessitating intravenous contrast agents. To date there is limited knowldedge about intravesical interactions between different types of contrast agents. To assess the effect of excreted intravenous iodinated and gadolinium-based contrast agents on the intravesical distribution of ultrasound contrast within contrast-enhanced voiding urosonography. Iodinated (iomeprol, iopamidol) and gadolinium-based (gadoterate meglumine) contrast agents were diluted to bladder concentration and injected into balloons filled with saline solution. CT scans were performed to assess the contrast distribution in these phantoms. Regions of interest were placed at the top and bottom side of each balloon and Hounsfield units (HU) were measured. Three other balloons were filled with saline solution and contrast media likewise. The ultrasound contrast agent sulphur hexafluoride was added and its distribution was assessed using sonography. MDCT scans showed a separation of two liquid layers in all bladder phantoms with the contrast layers located at the bottom and the saline solution at the top. Significant differences of the HU measurements at the top and bottom side were observed (P < 0.001-0.007). Following injection of ultrasound contrast agent, US showed its distribution exclusively among the saline solution. False-negative results of contrast-enhanced voiding urosonography may occur if it is performed shortly after imaging procedures requiring intravenous contrast. (orig.)

  5. 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

  6. 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.)

  7. WE-FG-207B-12: Quantitative Evaluation of a Spectral CT Scanner in a Phantom Study: Results of Spectral Reconstructions

    International Nuclear Information System (INIS)

    Duan, X; Arbique, G; Guild, J; Anderson, J; Yagil, Y

    2016-01-01

    Purpose: To evaluate the quantitative image quality of spectral reconstructions of phantom data from a spectral CT scanner. Methods: The spectral CT scanner (IQon Spectral CT, Philips Healthcare) is equipped with a dual-layer detector and generates conventional 80-140 kVp images and variety of spectral reconstructions, e.g., virtual monochromatic (VM) images, virtual non-contrast (VNC) images, iodine maps, and effective atomic number (Z) images. A cylindrical solid water phantom (Gammex 472, 33 cm diameter and 5 cm thick) with iodine (2.0-20.0 mg I/ml) and calcium (50-600 mg/ml) rod inserts was scanned at 120 kVp and 27 mGy CTDIvol. Spectral reconstructions were evaluated by comparing image measurements with theoretical values calculated from nominal rod compositions provided by the phantom manufacturer. The theoretical VNC was calculated using water and iodine basis material decomposition, and the theoretical Z was calculated using two common methods, the chemical formula method (Z1) and the dual-energy ratio method (Z2). Results: Beam-hardening-like artifacts between high-attenuation calcium rods (≥300 mg/ml, >800 HU) influenced quantitative measurements, so the quantitative analysis was only performed on iodine rods using the images from the scan with all the calcium rods removed. The CT numbers of the iodine rods in the VM images (50∼150 keV) were close to theoretical values with average difference of 2.4±6.9 HU. Compared with theoretical values, the average difference for iodine concentration, VNC CT number and effective Z of iodine rods were −0.10±0.38 mg/ml, −0.1±8.2 HU, 0.25±0.06 (Z1) and −0.23±0.07 (Z2). Conclusion: The results indicate that the spectral CT scanner generates quantitatively accurate spectral reconstructions at clinically relevant iodine concentrations. Beam-hardening-like artifacts still exist when high-attenuation objects are present and their impact on patient images needs further investigation. YY is an employee of Philips

  8. WE-FG-207B-12: Quantitative Evaluation of a Spectral CT Scanner in a Phantom Study: Results of Spectral Reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Duan, X; Arbique, G; Guild, J; Anderson, J [UT Southwestern Medical Center, Dallas, TX (United States); Yagil, Y [Philips Healthcare, Haifa (Israel)

    2016-06-15

    Purpose: To evaluate the quantitative image quality of spectral reconstructions of phantom data from a spectral CT scanner. Methods: The spectral CT scanner (IQon Spectral CT, Philips Healthcare) is equipped with a dual-layer detector and generates conventional 80-140 kVp images and variety of spectral reconstructions, e.g., virtual monochromatic (VM) images, virtual non-contrast (VNC) images, iodine maps, and effective atomic number (Z) images. A cylindrical solid water phantom (Gammex 472, 33 cm diameter and 5 cm thick) with iodine (2.0-20.0 mg I/ml) and calcium (50-600 mg/ml) rod inserts was scanned at 120 kVp and 27 mGy CTDIvol. Spectral reconstructions were evaluated by comparing image measurements with theoretical values calculated from nominal rod compositions provided by the phantom manufacturer. The theoretical VNC was calculated using water and iodine basis material decomposition, and the theoretical Z was calculated using two common methods, the chemical formula method (Z1) and the dual-energy ratio method (Z2). Results: Beam-hardening-like artifacts between high-attenuation calcium rods (≥300 mg/ml, >800 HU) influenced quantitative measurements, so the quantitative analysis was only performed on iodine rods using the images from the scan with all the calcium rods removed. The CT numbers of the iodine rods in the VM images (50∼150 keV) were close to theoretical values with average difference of 2.4±6.9 HU. Compared with theoretical values, the average difference for iodine concentration, VNC CT number and effective Z of iodine rods were −0.10±0.38 mg/ml, −0.1±8.2 HU, 0.25±0.06 (Z1) and −0.23±0.07 (Z2). Conclusion: The results indicate that the spectral CT scanner generates quantitatively accurate spectral reconstructions at clinically relevant iodine concentrations. Beam-hardening-like artifacts still exist when high-attenuation objects are present and their impact on patient images needs further investigation. YY is an employee of Philips

  9. Phantom black holes and critical phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Azreg-Aïnou, Mustapha [Engineering Faculty, Başkent University, Bağlıca Campus, Ankara (Turkey); Marques, Glauber T. [Universidade Federal Rural da Amazônia ICIBE-LASIC, Av. Presidente Tancredo Neves 2501, CEP 66077-901—Belém/PA (Brazil); Rodrigues, Manuel E., E-mail: azreg@baskent.edu.tr, E-mail: gtadaiesky@hotmail.com, E-mail: esialg@gmail.com [Faculdade de Ciências Exatas e Tecnologia, Universidade Federal do Pará, Campus Universitário de Abaetetuba, CEP 68440-000, Abaetetuba, Pará (Brazil)

    2014-07-01

    We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordström black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated.

  10. Results from the DCH-1 [Direct Containment Heating] experiment

    International Nuclear Information System (INIS)

    Tarbell, W.W.; Brockmann, J.E.; Pilch, M.; Ross, J.E.; Oliver, M.S.; Lucero, D.A.; Kerley, T.E.; Arellano, F.E.; Gomez, R.D.

    1987-05-01

    The DCH-1 (Direct Containment Heating) test was the first experiment performed in the Surtsey Direct Heating Test Facility. The test involved 20 kg of molten core debris simulant ejected into a 1:10 scale model of the Zion reactor cavity. The melt was produced by a metallothermic reaction of iron oxide and aluminum powders to yield molten iron and alumina. The cavity model was placed so that the emerging debris propagated directly upwards along the vertical centerline of the chamber. Results from the experiment showed that the molten material was ejected from the caviity as a cloud of particles and aerosol. The dispersed debris caused a rapid pressurization of the 103-m 3 chamber atmosphere. Peak pressure from the six transducers ranged from 0.09 to 0.13 MPa (13.4 to 19.4 psig) above the initial value in the chamber. Posttest debris collection yielded 11.6 kg of material outside the cavity, of which approximately 1.6 kg was attributed to the uptake of oxygen by the iron particles. Mechanical sieving of the recovered debris showed a lognormal size distribution with a mass mean size of 0.55 mm. Aerosol measurements indicated a subsantial portion (2 to 16%) of the ejected mass was in the size range less than 10 m aerodynamic equivalent diameter

  11. 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)

  12. 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

  13. Production of molten UO2 pools by internal heating: apparatus and preliminary experimental heat transfer results

    International Nuclear Information System (INIS)

    Chasanov, M.G.; Gunther, W.H.; Baker, L. Jr.

    1977-01-01

    The capability for removal of heat from a pool of molten fuel under postaccident conditions is an important consideration in liquid-metal fast breeder reactor safety analysis. No experimental data for pool heat transfer from molten UO 2 under conditions simulating internal heat generation by fission product decay have been reported previously in the literature. An apparatus to provide such data was developed and used to investigate heat transfer from pools containing up to 7.5 kg of UO 2 ; the internal heat generation rates and pool depths attained cover most of the ranges of interest for postaccident heat removal analysis. It was also observed in these studies that the presence of simulated fission products corresponding to approximately 150,000 kW-day/kg burnup had no significant effect on the observed heat transfer

  14. 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)

  15. Heating Development Analysis in Long HTS Objects - Updated Results

    Energy Technology Data Exchange (ETDEWEB)

    Vysotsky, V S; Repnikov, V V; Lobanov, E A; Karapetyan, G H; Sytnikov, V E [All-Russian Scientific R and D Cable Institute, 5, Shosse Entuziastov, 111024, Moscow (Russian Federation)

    2006-06-01

    During fault in a grid large overload current, up to 30-times fold, forcibly will go to an HTS superconducting cable installed in a grid causing its quench and heating. The upgraded model has been used to analyse the heating development in long HTS objects during overloads. The model better presents real properties of materials used. New calculations coincide well with experiments and permit to determine the cooling coefficients. The stability limit (thermal runaway current) was determined for different cooling and index n. The overload currents, at which the superconductor will be heated up to 100 K during 250 ms can be determined also. The model may be used for practical evaluations of operational parameters.

  16. Experimental results of a 3 k Wh thermochemical heat storage module for space heating application

    NARCIS (Netherlands)

    Finck, C.J.; Henquet, E.M.R.; Soest, C.F.L. van; Oversloot, H.P.; Jong, A.J. de; Cuypers, R.; Spijker, J.C. van 't

    2014-01-01

    A 3 kWh thermochemical heat storage (TCS) module was built as part of an all-in house system implementation focusing on space heating application at a temperature level of 40 ºC and a temperature lift of 20 K. It has been tested and measurements showed a maximum water circuit temperature span

  17. Active latent heat storage with a screw heat exchanger - experimental results for heat transfer and concept for high pressure steam

    Science.gov (United States)

    Zipf, Verena; Willert, Daniel; Neuhäuser, Anton

    2016-05-01

    An innovative active latent heat storage concept was invented and developed at Fraunhofer ISE. It uses a screw heat exchanger (SHE) for the phase change during the transport of a phase change material (PCM) from a cold to a hot tank or vice versa. This separates heat transfer and storage tank in comparison to existing concepts. A test rig has been built in order to investigate the heat transfer coefficients of the SHE during melting and crystallization of the PCM. The knowledge of these characteristics is crucial in order to assess the performance of the latent heat storage in a thermal system. The test rig contains a double shafted SHE, which is heated or cooled with thermal oil. The overall heat transfer coefficient U and the convective heat transfer coefficient on the PCM side hPCM both for charging and discharging have been calculated based on the measured data. For charging, the overall heat transfer coefficient in the tested SHE was Uch = 308 W/m2K and for discharging Udis = 210 W/m2K. Based on the values for hPCM the overall heat transfer coefficients for a larger SHE with steam as heat transfer fluid and an optimized geometry were calculated with Uch = 320 W/m2K for charging and Udis = 243 W/m2K for discharging. For pressures as high as p = 100 bar, an SHE concept has been developed, which uses an organic fluid inside the flight of the SHE as working media. With this concept, the SHE can also be deployed for very high pressure, e.g. as storage in solar thermal power plants.

  18. Comparison of LCA results of low temperature heat plant using electric heat pump, absorption heat pump and gas-fired boiler

    International Nuclear Information System (INIS)

    Nitkiewicz, Anna; Sekret, Robert

    2014-01-01

    Highlights: • Usage of geothermal heat pump can bring environmental benefits. • The lowest environmental impact for whole life cycle is obtained for absorption heat pump. • The value of heat pump COP has a significant influence on environmental impact. • In case of coal based power generation the damage to human health is significant. - Abstract: This study compares the life cycle impacts of three heating plant systems which differ in their source of energy and the type of system. The following heating systems are considered: electric water-water heat pump, absorption water-water heat pump and natural gas fired boiler. The heat source for heat pump systems is low temperature geothermal source with temperature below 20 °C and spontaneous outflow 24 m 3 /h. It is assumed that the heat pumps and boiler are working in monovalent system. The analysis was carried out for heat networks temperature characteristic at 50/40 °C which is changing with outdoor temperature during heating season. The environmental life cycle impact is evaluated within life cycle assessment methodological framework. The method used for life cycle assessment is eco-indicator ‘99. The functional unit is defined as heating plant system with given amount of heat to be delivered to meet local heat demand in assumed average season. The data describing heating plant system is derived from literature and energy analysis of these systems. The data describing the preceding life cycle phases: extraction of raw materials and fuels, production of heating devices and their transportation is taken from Ecoinvent 2.0 life cycle inventory database. The results were analyzed on three levels of indicators: single score indicator, damage category indicators and impact category indicator. The indicators were calculated for characterization, normalization and weighting phases as well. SimaPro 7.3.2 is the software used to model the systems’ life cycle. The study shows that heating plants using a low

  19. First results on a laser-heated emissive probe

    International Nuclear Information System (INIS)

    Madani, R.; Klinger, T.; Ionita, C.; Schrittwieser, R.

    2004-01-01

    The floating potential V(fl,em) of a probe, emitting a sufficiently high electron current, yields a fairly accurate approximation of Φ(pl). This is an advantage in comparison to the conventional Langmuir probe where, after determination of the electron temperature T e , the plasma potential can only be derived indirectly from the formula Φ(pl) = V(fl) + α*T e , where α is a function of the ratio of the electron to the ion saturation currents (α is around 2.4 in a magnetized hydrogen plasma). In addition, an emissive probe also works if there are electron drifts or beams in the plasma. Emissive probes are usually realised by small directly heated loops of W-wire. Drawbacks of this design are the limited lifetime, the low electron emissivity of W and the voltage drop across the wire. We have developed a new type of emissive probe, which is heated by an infrared high-power diode laser with a maximum output power of 50 W. The probe consists of a small cylinder of LaB 6 . The probe was inserted into the edge region of the VINETA helicon discharge plasma. Basic features of emissive probes were checked. (authors)

  20. Experimental result of BWR post-CHF tests. Critical heat flux and post-CHF heat transfer coefficient. Contract research

    International Nuclear Information System (INIS)

    Iguchi, Tadashi; Anoda, Yoshinari

    2002-02-01

    Authors performed post-CHF experiments under wider pressure ranges of 2 MPa - 18 MPa, wider mass flux ranges of 33 kg/m 2 s - 1651 kg/m 2 s and wider superheat of heaters up to 500 K in comparison to experimental ranges at previous post-CHF experiments. Data on boiling transition, critical heat flux and post-CHF heat transfer coefficient were obtained. Used test section was 4x4-rod bundle with heaters, which diameter and length were the same as those of BWR nuclear fuels. As the result of the experiments, it was found that the boiling transition occurred just below several grid spacers, and that the fronts of the boiling transition region proceeded lower with increase of heated power. Heat transfer was due to nucleate boiling above grid spacers, while it was due to film boiling below grid spacers. Consequently, critical heat flux is affected on the distance from the grid spacers. Critical heat flux above the grid spacers was about 15% higher than that below the grid spacers, by comparing them under the same local condition. Heat transfer by steam turbulent flow was dominant to post-CHF heat transfer, when superheat of heaters was sufficiently high. Then, post-CHF heat transfer coefficient was predicted with heat transfer correlations for single-phase flow. On the other hand, when superhead of heaters was not sufficiently high, post-CHF heat transfer coefficient was higher than the prediction with heat transfer correlations for single-phase flow. Mass flux effect on post-CHF heat transfer coefficient was described by standardization of post-CHF heat transfer coefficient with the prediction for single-phase flow. However, pressure effect, superheat effect and effect of position were not described. Authors clarified that those effects could be described with functions of heater temperature and position. Post-CHF heat transfer coefficient was lowest just blow the grid spacers, and it increased with the lower positions. It increased by about 30% in one span of the grid

  1. Experimental result of BWR post-CHF tests. Critical heat flux and post-CHF heat transfer coefficient. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Iguchi, Tadashi; Anoda, Yoshinari [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Iwaki, Chikako [Toshiba Corp., Tokyo (Japan)

    2002-02-01

    Authors performed post-CHF experiments under wider pressure ranges of 2 MPa - 18 MPa, wider mass flux ranges of 33 kg/m{sup 2}s - 1651 kg/m{sup 2}s and wider superheat of heaters up to 500 K in comparison to experimental ranges at previous post-CHF experiments. Data on boiling transition, critical heat flux and post-CHF heat transfer coefficient were obtained. Used test section was 4x4-rod bundle with heaters, which diameter and length were the same as those of BWR nuclear fuels. As the result of the experiments, it was found that the boiling transition occurred just below several grid spacers, and that the fronts of the boiling transition region proceeded lower with increase of heated power. Heat transfer was due to nucleate boiling above grid spacers, while it was due to film boiling below grid spacers. Consequently, critical heat flux is affected on the distance from the grid spacers. Critical heat flux above the grid spacers was about 15% higher than that below the grid spacers, by comparing them under the same local condition. Heat transfer by steam turbulent flow was dominant to post-CHF heat transfer, when superheat of heaters was sufficiently high. Then, post-CHF heat transfer coefficient was predicted with heat transfer correlations for single-phase flow. On the other hand, when superhead of heaters was not sufficiently high, post-CHF heat transfer coefficient was higher than the prediction with heat transfer correlations for single-phase flow. Mass flux effect on post-CHF heat transfer coefficient was described by standardization of post-CHF heat transfer coefficient with the prediction for single-phase flow. However, pressure effect, superheat effect and effect of position were not described. Authors clarified that those effects could be described with functions of heater temperature and position. Post-CHF heat transfer coefficient was lowest just blow the grid spacers, and it increased with the lower positions. It increased by about 30% in one span of

  2. 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

  3. 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

  4. Solar collectors and heat pump: Market review and preliminary simulation results

    International Nuclear Information System (INIS)

    Tepe, Rainer; Roennelid, Mats

    2002-01-01

    Heating systems that combine solar collectors and a heat pump available on the market in Sweden have been studied. A majority of the systems found combine the solar collectors with a ground source heat pump. The technology for combining the collectors and the heat pump does however vary considerably. In the most simple systems, the collectors heat the return water from the heat pump, i.e. the collectors are used for raising the temperature in the boreholes for the heat pump. In the advanced systems, the solar heat is used for tap water, space heating and for raising the temperature of the heat pump's evaporator. There exist only very few comparative evaluations of the contributions from solar collectors in heat pump systems, and there is a need for finding the potential for this technique. In the present study, results are reported from preliminary simulations of solar collectors and ground source heat pumps installed in one-family houses. Simulations are made for two heating loads: 8,650 and 16,500 kWh/year resp., and a hot water load of 3,000 kWh/year. The study shows that: the temperature of the borehole decreases when solar collectors are not used (about 1.2 deg C in three years): 8 m 2 glazed solar collectors used for hot water production can reduce the electricity consumption with up to 13%, with best results in the house with low heating load: 50 m 2 unglazed solar collectors coupled to the evaporator or the borehole can give reductions of up to 14%, largest reduction in the house with high heating load, where the heat extraction from the borehole is large: the unglazed collectors have the highest economic potential, and can be cost effective for houses with high heating load: the simulations do not include a thorough system optimization, better results can be expected from continued optimization work

  5. PANDA passive decay heat removal transient test results

    International Nuclear Information System (INIS)

    Bandurski, Th.; Dreier, J.; Huggenberger, M.

    1997-01-01

    PANDA is a large scale facility for investigating the long-term decay heat removal from the containment of a next generation of 'passive' Advanced Light Water Reactors (ALWR). PANDA was used to examine the long-term LOCA response of the Passive Containment Cooling System (PCCS) for the General Electric (GE) Simplified Boiling Water Reactor (SBWR). The first PANDA test series had the dual objectives of demonstrating the performance of the SBWR PCCS and extending the data base available for containment analysis code qualification. The test objectives also include the study of the effects of mixing and stratification of steam and noncondensible gases in the drywell (DW) and in the suppression chamber or wetwell (WW). Ten tests were conducted in the course of the PANDA SBWR Program. The tests demonstrated a favorable and robust overall PCCS performance under different conditions. The present paper focuses on the main phenomena observed during the tests with respect to PCCS operation and DW gas mixing. (author)

  6. The impact of heat waves on mortality in 9 European cities: results from the EuroHEAT project

    Directory of Open Access Journals (Sweden)

    Bisanti Luigi

    2010-07-01

    Full Text Available Abstract Background The present study aimed at developing a standardized heat wave definition to estimate and compare the impact on mortality by gender, age and death causes in Europe during summers 1990-2004 and 2003, separately, accounting for heat wave duration and intensity. Methods Heat waves were defined considering both maximum apparent temperature and minimum temperature and classified by intensity, duration and timing during summer. The effect was estimated as percent increase in daily mortality during heat wave days compared to non heat wave days in people over 65 years. City specific and pooled estimates by gender, age and cause of death were calculated. Results The effect of heat waves showed great geographical heterogeneity among cities. Considering all years, except 2003, the increase in mortality during heat wave days ranged from + 7.6% in Munich to + 33.6% in Milan. The increase was up to 3-times greater during episodes of long duration and high intensity. Pooled results showed a greater impact in Mediterranean (+ 21.8% for total mortality than in North Continental (+ 12.4% cities. The highest effect was observed for respiratory diseases and among women aged 75-84 years. In 2003 the highest impact was observed in cities where heat wave episode was characterized by unusual meteorological conditions. Conclusions Climate change scenarios indicate that extreme events are expected to increase in the future even in regions where heat waves are not frequent. Considering our results prevention programs should specifically target the elderly, women and those suffering from chronic respiratory disorders, thus reducing the impact on mortality.

  7. Results on heat transfer to He II for use in superconducting magnet technology

    International Nuclear Information System (INIS)

    Seyfert, P.

    1982-05-01

    The paper reviews several aspects of heat transfer to He II which are of practical interest for the cooling problem of superconductors. The heat transfer characteristics in the Kapitza boundary conductance regime are discussed and typical values for technical copper are given. It is shown how the peak heat flux depends on the boundary conditions of the bulk fluid and particularly on the time behaviour of heat sources. Results on transient recovery from film boiling applicable to superconductors are also presented

  8. The impact of heat waves on mortality in 9 European cities: results from the EuroHEAT project.

    Science.gov (United States)

    D'Ippoliti, Daniela; Michelozzi, Paola; Marino, Claudia; de'Donato, Francesca; Menne, Bettina; Katsouyanni, Klea; Kirchmayer, Ursula; Analitis, Antonis; Medina-Ramón, Mercedes; Paldy, Anna; Atkinson, Richard; Kovats, Sari; Bisanti, Luigi; Schneider, Alexandra; Lefranc, Agnès; Iñiguez, Carmen; Perucci, Carlo A

    2010-07-16

    The present study aimed at developing a standardized heat wave definition to estimate and compare the impact on mortality by gender, age and death causes in Europe during summers 1990-2004 and 2003, separately, accounting for heat wave duration and intensity. Heat waves were defined considering both maximum apparent temperature and minimum temperature and classified by intensity, duration and timing during summer. The effect was estimated as percent increase in daily mortality during heat wave days compared to non heat wave days in people over 65 years. City specific and pooled estimates by gender, age and cause of death were calculated. The effect of heat waves showed great geographical heterogeneity among cities. Considering all years, except 2003, the increase in mortality during heat wave days ranged from + 7.6% in Munich to + 33.6% in Milan. The increase was up to 3-times greater during episodes of long duration and high intensity. Pooled results showed a greater impact in Mediterranean (+ 21.8% for total mortality) than in North Continental (+ 12.4%) cities. The highest effect was observed for respiratory diseases and among women aged 75-84 years. In 2003 the highest impact was observed in cities where heat wave episode was characterized by unusual meteorological conditions. Climate change scenarios indicate that extreme events are expected to increase in the future even in regions where heat waves are not frequent. Considering our results prevention programs should specifically target the elderly, women and those suffering from chronic respiratory disorders, thus reducing the impact on mortality.

  9. IMRT credentialing for prospective trials using institutional virtual phantoms: results of a joint European Organization for the Research and Treatment of Cancer and Radiological Physics Center project

    International Nuclear Information System (INIS)

    Weber, Damien C; Vallet, Veronique; Molineu, Andrea; Melidis, Christos; Teglas, Vanda; Naudy, Suzanne; Moeckli, Raphael; Followill, David S; Hurkmans, Coen W

    2014-01-01

    Intensity-modulated radiotherapy (IMRT) credentialing for a EORTC study was performed using an anthropomorphic head phantom from the Radiological Physics Center (RPC; RPC PH ). Institutions were retrospectively requested to irradiate their institutional phantom (INST PH ) using the same treatment plan in the framework of a Virtual Phantom Project (VPP) for IMRT credentialing. CT data set of the institutional phantom and measured 2D dose matrices were requested from centers and sent to a dedicated secure EORTC uploader. Data from the RPC PH and INST PH were thereafter centrally analyzed and inter-compared by the QA team using commercially available software (RIT; ver.5.2; Colorado Springs, USA). Eighteen institutions participated to the VPP. The measurements of 6 (33%) institutions could not be analyzed centrally. All other centers passed both the VPP and the RPC ±7%/4 mm credentialing criteria. At the 5%/5 mm gamma criteria (90% of pixels passing), 11(92%) as compared to 12 (100%) centers pass the credentialing process with RPC PH and INST PH (p = 0.29), respectively. The corresponding pass rate for the 3%/3 mm gamma criteria (90% of pixels passing) was 2 (17%) and 9 (75%; p = 0.01), respectively. IMRT dosimetry gamma evaluations in a single plane for a H&N prospective trial using the INST PH measurements showed agreement at the gamma index criteria of ±5%/5 mm (90% of pixels passing) for a small number of VPP measurements. Using more stringent, criteria, the RPC PH and INST PH comparison showed disagreement. More data is warranted and urgently required within the framework of prospective studies

  10. 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

  11. Temperature mapping of laser-induced hyperthermia in an ocular phantom using magnetic resonance thermography.

    Science.gov (United States)

    Maswadi, Saher M; Dodd, Stephen J; Gao, Jia-Hong; Glickman, Randolph D

    2004-01-01

    Laser-induced heating in an ocular phantom is measured with magnetic resonance thermography (MRT) using temperature-dependent phase changes in proton resonance frequency. The ocular phantom contains a layer of melanosomes isolated from bovine retinal pigment epithelium. The phantom is heated by the 806-nm output of a continuous wave diode laser with an irradiance of 2.4 to 21.6 W/cm2 in a beam radius of 0.8 or 2.4 mm, depending on the experiment. MRT is performed with a 2 T magnet, and a two-turn, 6-cm-diam, circular radio frequency coil. Two-dimensional temperature gradients are measured within the plane of the melanin layer, as well as normal to it, with a temperature resolution of 1 degrees C or better. The temperature gradients extending within the melanin layer are broader than those orthogonal to the layer, consistent with the higher optical absorption and consequent heating in the melanin. The temperature gradients in the phantom measured by MRT closely approximate the predictions of a classical heat diffusion model. Three-dimensional temperature maps with a spatial resolution of 0.25 mm in all directions are also made. Although the temporal resolution is limited in the prototype system (22.9 s for a single image "slice"), improvements in future implementations are likely. These results indicate that MRT has sufficient spatial and temperature resolution to monitor target tissue temperature during transpupillary thermotherapy in the human eye.

  12. 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

  13. 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

  14. Results of heating mode performance tests of a solar-assisted heat pump

    Science.gov (United States)

    Jones, C. B.; Smetana, F. O.

    1979-01-01

    The performance of a heat pump, utilizing 8.16 square meters of low-cost solar collectors as the evaporator in a Freon-114 refrigeration cycle, was determined under actual insolation conditions during the summer and fall of 1976. C.O.P.'s (coefficient of performance) greater than 3 were obtained with condensing temperatures around 78 C and evaporating temperatures around 27 C. Ambient temperatures were about 3 C above evaporating temperatures. Similar performance levels were obtained at other insolation and temperature conditions. Experience with the system has identified some component and system changes which should increase the obtainable C.O.P. to about 4.0. These are described along with the system's design rationale. The accumulated data are presented as an appendix.

  15. A statistically defined anthropomorphic software breast phantom

    International Nuclear Information System (INIS)

    Lau, Beverly A.; Reiser, Ingrid; Nishikawa, Robert M.; Bakic, Predrag R.

    2012-01-01

    Purpose: Digital anthropomorphic breast phantoms have emerged in the past decade because of recent advances in 3D breast x-ray imaging techniques. Computer phantoms in the literature have incorporated power-law noise to represent glandular tissue and branching structures to represent linear components such as ducts. When power-law noise is added to those phantoms in one piece, the simulated fibroglandular tissue is distributed randomly throughout the breast, resulting in dense tissue placement that may not be observed in a real breast. The authors describe a method for enhancing an existing digital anthropomorphic breast phantom by adding binarized power-law noise to a limited area of the breast. Methods: Phantoms with (0.5 mm) 3 voxel size were generated using software developed by Bakic et al. Between 0% and 40% of adipose compartments in each phantom were replaced with binarized power-law noise (β = 3.0) ranging from 0.1 to 0.6 volumetric glandular fraction. The phantoms were compressed to 7.5 cm thickness, then blurred using a 3 × 3 boxcar kernel and up-sampled to (0.1 mm) 3 voxel size using trilinear interpolation. Following interpolation, the phantoms were adjusted for volumetric glandular fraction using global thresholding. Monoenergetic phantom projections were created, including quantum noise and simulated detector blur. Texture was quantified in the simulated projections using power-spectrum analysis to estimate the power-law exponent β from 25.6 × 25.6 mm 2 regions of interest. Results: Phantoms were generated with total volumetric glandular fraction ranging from 3% to 24%. Values for β (averaged per projection view) were found to be between 2.67 and 3.73. Thus, the range of textures of the simulated breasts covers the textures observed in clinical images. Conclusions: Using these new techniques, digital anthropomorphic breast phantoms can be generated with a variety of glandular fractions and patterns. β values for this new phantom are comparable

  16. Contrast-enhanced near-infrared laser mammography with a prototype breast scanner: feasibility study with tissue phantoms and preliminary results of imaging experimental tumors.

    Science.gov (United States)

    Boehm, T; Hochmuth, A; Malich, A; Reichenbach, J R; Fleck, M; Kaiser, W A

    2001-10-01

    Near-infrared (NIR) optical mammography without contrast has a low specificity. The application of optical contrast medium may improve the performance. The concentration-dependent detectability of a new NIR contrast medium was determined with a prototype optical breast scanner. In vivo imaging of experimental tumors was performed. The NIR contrast agent NIR96010 is a newly synthesized, hydrophilic contrast agent for NIR mammography. A concentration-dependent contrast resolution was determined for tissue phantoms consisting of whole milk powder and gelatin. A central part of the phantoms measuring 2 x 2 cm2 without contrast was replaced with phantom material containing 1 micromol/L to 25 nmol/L NIR96010. The composite phantoms were measured with a prototype NIR breast scanner with lasers of lambda1 = 785 nm and lambda2 = 850 nm wavelength. Intensity profiles and standard deviations of the transmission signal in areas with and without contrast were determined by linear fit procedures. Signal-to-noise ratios and spatial resolution as a function of contrast concentration were determined. Near-infrared imaging of five tumor-bearing SCID mice (MX1 breast adenocarcinoma, tumor diameter 5-10 mm) was performed before and after intravenous application of 2 micromol/kg NIR96010. Spectrometry showed an absorption maximum of the contrast agent at 755 nm. No spectral shifts occurred in protein-containing solution. Signal-to-noise ratio in the transmission intensity profiles ranged from 1.1 at 25 nmol/L contrast to 28 at 1 micromol/L. At concentrations contrast-enhanced images, with better delineation after contrast administration. In postcontrast absorption profiles, a 44.1% +/- 11.3% greater absorption increase was seen in tumor tissue compared with normal tissue. The laser wavelength lambda1 of the prototype laser mammography device was not situated at maximum absorption of the contrast agent NIR96010 but on the descending shoulder of the absorption spectrum. This implies a 20

  17. 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

  18. 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

  19. Solar heating by radiant floor: Experimental results and emission reduction obtained with a micro photovoltaic–heat pump system

    International Nuclear Information System (INIS)

    Izquierdo, M.; Agustín-Camacho, P. de

    2015-01-01

    Highlights: • This work presents a PVT multicrystalline solar heating system for buildings. • The PV DC electricity generated was converted to AC to drive an air–water heat pump. • Experimental results obtained from December 1, 2012 to April 30, 2013 are detailed. • An environmental study is also presented. - Abstract: An experimental research with a solar photovoltaic thermal (PVT) micro grid feeding a reversible air–water, 6 kW heating capacity heat pump, has been carried out from December 2012 to April 2013. Its purpose is to heat a laboratory that is used as a house prototype for the study of heating/cooling systems. It was built in accordance with the 2013 Spanish CTE, and has an area of 35 m 2 divided into two internal rooms: one of them housing the storage system, the solar controller, the inverter and the control system; the other one is occupied by three people. Its main thermal characteristics are: UA = 125 W/°C and a maximum thermal load about 6.0 kW at the initial time. The PVT field consists of 12 modules, with a total area of 15.7 m 2 and useful area of 14 m 2 . Each module is composed of 48 polycrystalline silicon cells of 243.4 cm 2 , which with a nominal efficiency 14% can generate a power of 180 W, being the total nominal power installed 2.16 kW. The PV system stores electricity in 250 Ah batteries from where is converted from DC to AC through a 3.0 kW inverter that feeds the heat pump. This works supplying 840 l/h of hot water at 35–45 °C to the radiant floor. The data storing system is recording variables such as solar radiation; temperatures; input power to batteries; heat produced; heat transferred by the radiant floor; heat pump’s COP; isolated ratio; and solar fraction. The objective of this work is to present and discuss the experimental results and the emission reduction of CO 2 obtained during the period from 01/12/2012 to 30/04/2013, including the detailed results of two representative days of Madrid’s climate: 28

  20. Experimental results of acetone hydrogenation on a heat exchanger type reactor for solar chemical heat pump; Solar chemical heat pump ni okeru acetone suisoka hanno netsu kaishu jikken

    Energy Technology Data Exchange (ETDEWEB)

    Takashima, T; Doi, T; Tanaka, T; Ando, Y [Electrotechnical Laboratory, Tsukuba (Japan); Miyahara, R; Kamoshida, J [Shibaura Institute of Technology, Tokyo (Japan)

    1996-10-27

    With the purpose of converting solar heat energy to industrial heat energy, an experiment of acetone hydrogenation was carried out using a heat exchanger type reactor that recovers heat generated by acetone hydrogenation, an exothermic reaction, and supplies it to an outside load. In the experiment, a pellet-like activated carbon-supported ruthenium catalyst was used for the acetone hydrogenation with hydrogen and acetone supplied to the catalyst layer at a space velocity of 400-1,200 or so. In the external pipe of the double-pipe type reactor, a heating medium oil was circulated in parallel with the flow of the reactant, with the heat of reaction recovered that was generated from the acetone hydrogenation. In this experiment, an 1wt%Ru/C catalyst and a 5wt%Ru/C catalyst were used so as to examine the effects of variation in the space velocity. As a result, from the viewpoint of recovering the heat of reaction, it was found desirable to increase the reaction speed by raising catalytic density and also to supply the reactant downstream inside the reaction pipe by increasing the space velocity. 1 ref., 6 figs., 1 tab.

  1. 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

  2. Main results of assessing integrity of RNPP-3 steam generator heat exchange tubes in accident management

    International Nuclear Information System (INIS)

    Shugajlo, Al-j P.; Mustafin, M.A.; Shugajlo, Al-r P.; Ryzhov, D.I.; Zhabin, O.I.

    2017-01-01

    Tubes integrity evaluation under accident conditions considering drain of SG and current technical state of steam exchange tubes is an important question regarding SG long-term operation and improvement of accident management strategy.The main investigation results prepared for heat exchange surface of RNPP-3 steam generator are presented in this research aimed at assessing integrity of heat exchange tubes under accident conditions, which lead to full or partial drain of heat exchange surface, in particular during station blackout.

  3. Individual virtual phantom reconstruction for organ dosimetry based on standard available phantoms

    International Nuclear Information System (INIS)

    Babapour Mofrad, F.; Aghaeizadeh Zoroofi, R.; Abbaspour Tehran Fard, A.; Akhlaghpoor, Sh.; Chen, Y. W.; Sato, Y.

    2010-01-01

    In nuclear medicine application often it is required to use computational methods for evaluation of organ absorbed dose. Monte Carlo Simulation and phantoms have been used in many works before. The shape, size and volume In organs are varied, and this variation will produce error in dose calculation if no correction is applied. Materials and Methods: A computational framework for constructing individual phantom for dosimetry was performed on five liver CT scan data sets of Japanese normal individuals. The Zubal phantom was used as an original phantom to be adjusted by each individual data set. This registration was done by Spherical Harmonics and Thin-Plate Spline methods. Hausdorff distance was calculated for each case. Results: Result of Hausdorff distance for five lndividual phantoms showed that before registration ranged from 140.9 to 192.1, and after registration it changed to 52.5 to 76.7. This was caused by Index similarity ranged from %56.4 to %70.3. Conclusion: A new and automatic three-dimensional (3D) phantom construction approach was-suggested for individual internal dosimetry simulation via Spherical Harmonics and Thin-Plate Spline methods. The results showed that the Individual comparable phantom can be calculated with acceptable accuracy using geometric registration. This method could be used for race-specific statistical phantom modeling with major application in nuclear medicine for absorbed dose calculation.

  4. Results from evaporation tests to support the MWTF heat removal system design

    International Nuclear Information System (INIS)

    Crea, B.A.

    1994-01-01

    An experimental tests program was conducted to measure the evaporative heat removal from the surface of a tank of simulated waste. The results contained in this report constitute definition design data for the latest heat removal function of the MWTF primary ventilation system

  5. First results of a coated heat exchanger for the use in dehumidification and cooling processes

    International Nuclear Information System (INIS)

    Munz, Gunther M.; Bongs, C.; Morgenstern, A.; Lehmann, S.; Kummer, H.; Henning, H.-M.; Henninger, Stefan K.

    2013-01-01

    In this work a novel solar driven dehumidification and cooling system is presented. The core components of this combined system are a sorptive dehumidification device based on high performance sorptive coatings and a novel evacuated tube solar air collector providing the driving heat. The essential part of the system is the coated heat exchanger. The chosen adsorbent is attached to the heat exchanger surface by a newly developed coating technique. Besides a brief description of the novel components and the experimental setup, the development of the aluminum heat exchanger, the coating procedure and scale up for geometries comparable to the heat exchanger in the dehumidification setup, as well as a first characterization of a small-sized coated heat exchanger regarding water uptake and dehumidification performance are presented. For estimating an overall system performance, a 2-dimensional thermodynamic model was applied, using the parameters in focus for the development of heat exchanger, coating and demonstration system. Highlights: • A novel developed technology is applied for sorptive coating of heat exchangers. • Upscaling to dimensions of 100 × 100 × 400 mm 3 was successful. • A small scale heat exchanger was coated and characterized showing good results. • Evaluation of adsorbents and simulation of system performance were carried out. • SAPO-34 gives best performance for driving temperatures of 100 °C and above

  6. Dose distribution in organs: patient-specific phantoms versus reference phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, I.V.B., E-mail: isabelle.lacerda@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Vieira, J.W. [Instituto Federal de Pernambuco (IFPE), Recife (Brazil); Oliveira, M.L.; Lima, F.R.A. [Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE/CNEN-PB), Recife (Brazil)

    2017-07-01

    Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

  7. Dose distribution in organs: patient-specific phantoms versus reference phantoms

    International Nuclear Information System (INIS)

    Lacerda, I.V.B.; Vieira, J.W.; Oliveira, M.L.; Lima, F.R.A.

    2017-01-01

    Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

  8. 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)

  9. Toxicology Analysis of Tissue-Mimicking Phantom Made From Gelatin

    Science.gov (United States)

    Dolbashid, A. S.; Hamzah, N.; Zaman, W. S. W. K.; Mokhtar, M. S.

    2017-06-01

    Skin phantom mimics the biological skin tissues as it have the ability to respond to changes in its environment. The development of tissue-mimicking phantom could contributes towards the reduce usage of animal in cosmetics and pharmacokinetics. In this study, the skin phantoms made from gelatin were tested with four different commonly available cosmetic products to determine the toxicity of each substance. The four substances used were; mercury-based whitening face cream, carcinogenic liquid make-up foundation, paraben-based acne cleanser, and organic lip balm. Toxicity test were performed on all of the phantoms. For toxicity testing, topographical and electrophysiological changes of the phantoms were evaluated. The ability of each respective phantom to react with mild toxic substances and its electrical resistance were analysed in to determine the toxicity of all the phantom models. Four-electrode method along with custom made electrical impedance analyser was used to differentiate electrical resistance between intoxicated phantom and non-intoxicated phantom in this study. Electrical resistance values obtained from the phantom models were significantly higher than the control group. The result obtained suggests the phantom as a promising candidate to be used as alternative for toxicology testing in the future.

  10. Results of investigation of spray controlled heat transfer crisis in tubes

    International Nuclear Information System (INIS)

    Sapankevich, A.P.; Kalinina, O.K.; Selivanov, Yu.F.

    1984-01-01

    Coefficient of liquid phase mass transfer is a determining parameter in tubes at crisis controlled with precipitating on heat surface a liquid phase carried in flow. To determine mass transfer coefficients in 4-14 MPa pressure range at 400-2000 kg/m 2 s mass velocities, special experiments were performed in experimental section consisting of two independently heated tubes in-series-connected along the flow. Heat transfer crisis was reached simultaneously in two sections which permitted to eliminate influence of liquid flowing on the wall in the controlsection. A part of heat removed due to forced convection was taken account of during calculation of mass transfer coefficient. Processing results are presented in the criterional form. Mean-square deviation with respect to massive obtained was amounted to 24% during calculation of the mass transfer coefficient and 20% during calculation of critical heat flux

  11. 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....

  12. Development of a physical 3D anthropomorphic breast phantom

    Energy Technology Data Exchange (ETDEWEB)

    Carton, Ann-Katherine; Bakic, Predrag; Ullberg, Christer; Derand, Helen; Maidment, Andrew D. A. [Department of Radiology, University of Pennsylvania, 1 Silverstein Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104-4206 (United States); XCounter AB, Svaerdvaegen 11, SE-182 33 Danderyd (Sweden); Department of Radiology, University of Pennsylvania, 1 Silverstein Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104-4206 (United States)

    2011-02-15

    Purpose: Develop a technique to fabricate a 3D anthropomorphic breast phantom with known ground truth for image quality assessment of 2D and 3D breast x-ray imaging systems. Methods: The phantom design is based on an existing computer model that can generate breast voxel phantoms of varying composition, size, and shape. The physical phantom is produced in two steps. First, the portion of the voxel phantom consisting of the glandular tissue, skin, and Cooper's ligaments is separated into sections. These sections are then fabricated by high-resolution rapid prototyping using a single material with 50% glandular equivalence. The remaining adipose compartments are then filled using an epoxy-based resin (EBR) with 100% adipose equivalence. The phantom sections are stacked to form the physical anthropomorphic phantom. Results: The authors fabricated a prototype phantom corresponding to a 450 ml breast with 45% dense tissue, deformed to a 5 cm compressed thickness. Both the rapid prototype (RP) and EBR phantom materials are radiographically uniform. The coefficient of variation (CoV) of the relative attenuation between RP and EBR phantom samples was <1% and the CoV of the signal intensity within RP and EBR phantom samples was <1.5% on average. Digital mammography and reconstructed digital breast tomosynthesis images of the authors' phantom were reviewed by two radiologists; they reported that the images are similar in appearance to clinical images, noting there are still artifacts from air bubbles in the EBR. Conclusions: The authors have developed a technique to produce 3D anthropomorphic breast phantoms with known ground truth, yielding highly realistic x-ray images. Such phantoms may serve both qualitative and quantitative performance assessments for 2D and 3D breast x-ray imaging systems.

  13. Anthropogenic Heat Flux Estimation from Space: Results of the second phase of the URBANFLUXES Project

    Science.gov (United States)

    Chrysoulakis, Nektarios; Marconcini, Mattia; Gastellu-Etchegorry, Jean-Philippe; Grimmond, Sue; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Landier, Lucas; Gabey, Andy; Parlow, Eberhard; Olofson, Frans

    2017-04-01

    The H2020-Space project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic heat flux, as a key component of the Urban Energy Budget (UEB). URBANFLUXES advances the current knowledge of the impacts of UEB fluxes on urban heat island and consequently on energy consumption in cities. In URBANFLUXES, the anthropogenic heat flux is estimated as a residual of UEB. Therefore, the rest UEB components, namely, the net all-wave radiation, the net change in heat storage and the turbulent sensible and latent heat fluxes are independently estimated from Earth Observation (EO), whereas the advection term is included in the error of the anthropogenic heat flux estimation from the UEB closure. The Discrete Anisotropic Radiative Transfer (DART) model is employed to improve the estimation of the net all-wave radiation balance, whereas the Element Surface Temperature Method (ESTM), adjusted to satellite observations is used to improve the estimation the estimation of the net change in heat storage. Furthermore the estimation of the turbulent sensible and latent heat fluxes is based on the Aerodynamic Resistance Method (ARM). Based on these outcomes, QF is estimated by regressing the sum of the turbulent heat fluxes versus the available energy. In-situ flux measurements are used to evaluate URBANFLUXES outcomes, whereas uncertainties are specified and analyzed. URBANFLUXES is expected to prepare the ground for further innovative exploitation of EO in scientific activities (climate variability studies at local and regional scales) and future and emerging applications (sustainable urban planning, mitigation technologies) to benefit climate change mitigation/adaptation. This study presents the results of the second phase of the project and detailed information on URBANFLUXES is available at: http://urbanfluxes.eu

  14. Results of high heat flux tests of tungsten divertor targets under plasma heat loads expected in ITER and tokamaks (review)

    Energy Technology Data Exchange (ETDEWEB)

    Budaev, V. P., E-mail: budaev@mail.ru [National Research Centre Kurchatov Institute (Russian Federation)

    2016-12-15

    Heat loads on the tungsten divertor targets in the ITER and the tokamak power reactors reach ~10MW m{sup −2} in the steady state of DT discharges, increasing to ~0.6–3.5 GW m{sup −2} under disruptions and ELMs. The results of high heat flux tests (HHFTs) of tungsten under such transient plasma heat loads are reviewed in the paper. The main attention is paid to description of the surface microstructure, recrystallization, and the morphology of the cracks on the target. Effects of melting, cracking of tungsten, drop erosion of the surface, and formation of corrugated and porous layers are observed. Production of submicron-sized tungsten dust and the effects of the inhomogeneous surface of tungsten on the plasma–wall interaction are discussed. In conclusion, the necessity of further HHFTs and investigations of the durability of tungsten under high pulsed plasma loads on the ITER divertor plates, including disruptions and ELMs, is stressed.

  15. Performance investigation of a lab–scale latent heat storage prototype – Numerical results

    International Nuclear Information System (INIS)

    Niyas, Hakeem; Prasad, Sunku; Muthukumar, P.

    2017-01-01

    Highlights: • Developed a numerical tool for analyzing a shell-and-tube LHS system. • Effective heat capacity method is used for incorporating the latent heat. • Number of heat transfer fluid tubes and fins are optimized. • Partial charging/discharging is efficient than complete charging/discharging. • Numerically predicted values match well with the experimental results. - Abstract: In the current study, numerical analysis of the charging and discharging characteristics of a lab-scale latent heat storage (LHS) prototype is presented. A mathematical model is developed to analyze the performance characteristics of the LHS prototype of shell and tube heat exchanger configuration. Effective heat capacity (EHC) method is implemented to consider the latent heat of the phase change material (PCM) and Boussinesq approximation is used to incorporate the buoyancy effect of the molten layer of the PCM in the model. For proper modeling of velocities in the PCM, Darcy law’s source term is added. The governing equations involved in the model are solved using a finite element based software product, COMSOL Multiphysics 4.3a. The number of embedded tubes and fins on the embedded tubes are optimized based on the discharging time of the model. Various performance parameters such as charging/discharging time, energy storage/discharge rate and melt fraction are evaluated. Numerically predicted temperature variations of the model during charging and discharging processes were compared with the experimental data extracted from the lab-scale LHS prototype and a good agreement was found between them.

  16. 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

  17. Selenide isotope generator for the Galileo Mission. Axially-grooved heat pipe: accelerated life test results

    International Nuclear Information System (INIS)

    1979-08-01

    The results through SIG/Galileo contract close-out of accelerated life testing performed from June 1978 to June 1979 on axially-grooved, copper/water heat pipes are presented. The primary objective of the test was to determine the expected lifetime of axially-grooved copper/water heat pipes. The heat pipe failure rate, due to either a leak or a build-up of non-condensible gas, was determined. The secondary objective of the test was to determine the effects of time and temperature on the thermal performance parameters relevant to long-term (> 50,000 h) operation on a space power generator. The results showed that the gas generation rate appears to be constant with time after an initial sharp rise although there are indications that it drops to approximately zero beyond approx. 2000 h. During the life test, the following pipe-hours were accumulated: 159,000 at 125 0 C, 54,000 at 165 0 C, 48,000 at 185 0 C, and 8500 at 225 0 C. Heated hours per pipe ranged from 1000 to 7500 with an average of 4720. Applying calculated acceleration factors yields the equivalent of 930,000 pipe-h at 125 0 C. Including the accelerated hours on vendor tested pipes raises this number to 1,430,000 pipe-hours at 125 0 C. It was concluded that, for a heat pipe temperature of 125 0 C and a mission time of 50,000 h, the demonstrated heat pipe reliability is between 80% (based on 159,000 actual pipe-h at 125 0 C) and 98% (based on 1,430,000 accelerated pipe-h at 125 0 C). Measurements indicate some degradation of heat transfer with time, but no detectable degradation of heat transport

  18. Some results of heating of a thick-walled cylinder fragment

    International Nuclear Information System (INIS)

    Zholdak, G.I.; Solov'ev, A.P.

    1977-01-01

    The effect of heat cycles on a reinforced concrete structure has been experimentally investigated. A reinforced concrete ring structure, reinforced on two sides, has been subjected to heat treatment by a complex heating cycle within a temperature range of from 20 to 300 deg C. The heating rate being 20 deg/hour and the total number of the cooling-heating cycles - 300. The cracking behaviour has been studied by ultrasonic inspection. In theoretical treatment, the principal relationships of the theory of elasticity have been used with account for the variations in the physico-mechanical properties of concrete and the development of nonelastic strains. The results have demonstrated both the applicability of the underlying theoretical calculations and the very feasibility of using reinforced concrete under cyclic heating conditions. The effect of cracks in the structure can be easily taken into account as it is remembered that the crack depth is 500 to 700 times greater than their mean exposure on the tensile surface of concrete

  19. Investigation of radiofrequency heating for a closed conducting loop formed in a part of the patient's body in 1.5 tesla magnetic resonance (MR) imaging and 3.0 tesla MR imaging. Measurement of temperature by use of human body-equivalent phantom

    International Nuclear Information System (INIS)

    Yamazaki, Masaru; Higashida, Mitsuji; Kudo, Sadahiro; Ideta, Takahiro; Nakazawa, Masami

    2012-01-01

    Thermal injuries have been sometimes reported due to a closed conducting loop formed in a part of the patient's body during magnetic resonance imaging (MRI). In recent years, 3.0 T-MRI scanner has been widely used. However, it is considered that the specific absorption rate (SAR) of 3.0 T-MRI can affect the heat of the loop because its own SAR becomes approximately 4 times as much as that of the 1.5 T-MRI scanner. With this, the change in temperature was measured with human body-equivalent loop phantom in both 1.5 T-MRI and 3.0 T-MRI. In the two scanners, the temperature during 20 min of scanning time was measured with three types of sequences such as field echo (FE), spin echo (SE), and turbo SE (TSE) set up with the same scanning condition. It was found from the result that rise in temperature depended on SAR of the scanning condition irrespective of static magnetic field intensity and any pulse sequences. Furthermore, the increase of SAR and rise in temperature were not only in proportion to each other but also were indicated to have good correlation. However, even low SAR can occasionally induce serious thermal injuries. It was found from result that we had to attempt not to form a closed conducting loop with in a part of the patient's body during MRI. (author)

  20. Coupled oscillators as models of phantom and scalar field cosmologies

    International Nuclear Information System (INIS)

    Faraoni, Valerio

    2004-01-01

    We study a toy model for phantom cosmology recently introduced in the literature and consisting of two oscillators, one of which carries negative kinetic energy. The results are compared with the exact phase space picture obtained for similar dynamical systems describing, respectively, a massive canonical scalar field conformally coupled to the spacetime curvature and a conformally coupled massive phantom. Finally, the dynamical system describing exactly a minimally coupled phantom is studied and compared with the toy model

  1. Creating 3D gelatin phantoms for experimental evaluation in biomedicine

    Directory of Open Access Journals (Sweden)

    Stein Nils

    2015-09-01

    Full Text Available We describe and evaluate a setup to create gelatin phantoms by robotic 3D printing. Key aspects are the large workspace, reproducibility and resolution of the created phantoms. Given its soft tissue nature, the gelatin is kept fluid during inside the system and we present parameters for additive printing of homogeneous, solid objects. The results indicate that 3D printing of gelatin can be an alternative for quickly creating larger soft tissue phantoms without the need for casting a mold.

  2. Major results of the electron cyclotron heating experiment in the PDX tokamak

    International Nuclear Information System (INIS)

    Hsuan, H.; Bol, K.; Bowen, N.

    1984-07-01

    Electron Cyclotron Heating (ECH) experiments on PDX have been carried out with two 60 GHz pulsed gyrotrons each yielding up to approximately 100 kW. The ECH system used two waveguide runs each about 30 meters long. One run included 5 bends and the other, 7 bends. Predetermined waveguide modes were transmitted. The electron cyclotron waves were launched in narrow beams from both the high field and the low field sides of the plasma torus. The major new physics results are: (1) efficient central electron heating for both ohmic and neutral beam heated target plasmas; (2) alteration of MHD behavior using ECH; (3) identification of the trapped electron population with ECH; and (4) signature of velocity-space time evolution during ECH. In the best heating results obtained, Thomson scattering data indicated a central temperature increase from less than or equal to 1.5 keV to greater than or equal to 2.5 keV. This occurred with an average density of about 10 13 cm -3 and approximately 80 kW outside-launch ordinary-mode heating

  3. Deformable and durable phantoms with controlled density of scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Bisaillon, Charles-Etienne; Lamouche, Guy; Dufour, Marc; Monchalin, Jean-Pierre [Industrial Materials Institute, National Research Council Canada, 75 de Mortagne, Boucherville, Quebec J4B 6Y4 (Canada); Maciejko, Romain [Optoelectronics Laboratory, Engineering Physics, Ecole Polytechnique de Montreal, PO Box 6079, Station ' Centre-ville' Montreal, Quebec H3C 3A7 (Canada)], E-mail: charles-etienne.bisaillon@cnrc-nrc.gc.ca, E-mail: guy.lamouche@cnrc-nrc.gc.ca, E-mail: marc.dufour@cnrc-nrc.gc.ca, E-mail: jean-pierre.monchalin@cnrc-nrc.gc.ca, E-mail: romain.maciejko@polytml.ca

    2008-07-07

    We have developed deformable and durable optical tissue phantoms with a simple and well-defined microstructure including a novel combination of scatterers and a matrix material. These were developed for speckle and elastography investigations in optical coherence tomography, but should prove useful in many other fields. We present in detail the fabrication process which involves embedding silica microspheres in a silicone matrix. We also characterize the resulting phantoms with scanning electron microscopy and optical measurements. To our knowledge, no such phantoms were proposed in the literature before. Our technique has a wide range of applicability and could also be adapted to fabricate phantoms with various optical and mechanical properties. (note)

  4. 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.

  5. Racetrack coil instability resulting from friction-heat generation at fixtures

    International Nuclear Information System (INIS)

    Yazawa, T.; Urata, M.; Chandratilleke, G.R.; Maeda, H.

    1993-01-01

    This paper describes racetrack coil instability resulting from friction-heat generation at fixtures and a preventive measure against it using a thermal barrier. Epoxy impregnated racetrack coils sometimes experience premature quenches due to frictional heat produced by coil slides at fixtures that are essential for the coil straight part to withstand the electromagnetic force. Experimentally, we confirmed for a small-sized racetrack coil that coil slides were actually occurring. The coil movements coupled with acoustic emissions were observed several times when the coil was energized. Each of them was about 10 μm, an equivalent of 20 mJ in frictional heat. This frictional heat was almost comparable with the analytical and experimental coil stability margins when an insulation layer was thin. One of the effective measures against the frictional heat is the thermal barrier, which is a thick insulation layer at the interface between the coil and the fixtures. By thickening the insulation layer from 0.36 to 1.00 mm, the coil stability margin increased from 100 to 200 mJ. (orig.)

  6. Using Remote Sensing Data and Research Results for Urban Heat Island Mitigation

    Science.gov (United States)

    Estes, Maury; Luvall, Jeffrey

    1999-01-01

    This paper provides information on the characteristics of the urban heat island, research designed to provide the data needed to develop effective urban heat island reduction strategies, and the development of local working groups to develop implementation plans. As background, an overview of research results on the urban heat island phenomenon and the resultant effect on energy usage and air quality will be explored. The use of more reflective roofing materials, paving materials, tree planting, and other initiatives will be explored as a basis for strategies to mitigate urban heat islands and improve the urban environment. Current efforts to use aircraft remote sensing data in Atlanta, Baton Rouge, Sacramento, and Salt Lake City and our work with non-profit organizations designated to lead public education and strategic development efforts will be presented. Efforts to organize working groups comprised of key stakeholders, the process followed in communicating research results, and methodology for soliciting feedback and incorporating ideas into local plans, policies and decision-making will be discussed. Challenges in developing and transferring data products and research results to stakeholders will be presented. It is our ultimate goal that such efforts be integrated into plans and/or decision models that encourage sustainable development.

  7. Transorbital therapy delivery: phantom testing

    Science.gov (United States)

    Ingram, Martha-Conley; Atuegwu, Nkiruka; Mawn, Louise; Galloway, Robert L.

    2011-03-01

    We have developed a combined image-guided and minimally invasive system for the delivery of therapy to the back of the eye. It is composed of a short 4.5 mm diameter endoscope with a magnetic tracker embedded in the tip. In previous work we have defined an optimized fiducial placement for accurate guidance to the back of the eye and are now moving to system testing. The fundamental difficulty in testing performance is establishing a target in a manner which closely mimics the physiological task. We have to have a penetrable material which obscures line of sight, similar to the orbital fat. In addition we need to have some independent measure of knowing when a target has been reached to compare to the ideal performance. Lastly, the target cannot be rigidly attached to the skull phantom since the optic nerve lies buried in the orbital fat. We have developed a skull phantom with white cloth stellate balls supporting a correctly sized globe. Placed in the white balls are red, blue, orange and yellow balls. One of the colored balls has been soaked in barium to make it bright on CT. The user guides the tracked endoscope to the target as defined by the images and tells us its color. We record task accuracy and time to target. We have tested this with 28 residents, fellows and attending physicians. Each physician performs the task twice guided and twice unguided. Results will be presented.

  8. 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

  9. Designing a compact MRI motion phantom

    Directory of Open Access Journals (Sweden)

    Schmiedel Max

    2016-09-01

    Full Text Available Even today, dealing with motion artifacts in magnetic resonance imaging (MRI is a challenging task. Image corruption due to spontaneous body motion complicates diagnosis. In this work, an MRI phantom for rigid motion is presented. It is used to generate motion-corrupted data, which can serve for evaluation of blind motion compensation algorithms. In contrast to commercially available MRI motion phantoms, the presented setup works on small animal MRI systems. Furthermore, retrospective gating is performed on the data, which can be used as a reference for novel motion compensation approaches. The motion of the signal source can be reconstructed using motor trigger signals and be utilized as the ground truth for motion estimation. The proposed setup results in motion corrected images. Moreover, the importance of preprocessing the MRI raw data, e.g. phase-drift correction, is demonstrated. The gained knowledge can be used to design an MRI phantom for elastic motion.

  10. Determination of photon conversion factors relating exposure and dose for several extremity phantom designs

    International Nuclear Information System (INIS)

    Roberson, P.L.; Eichner, F.N.; Reece, W.D.

    1986-09-01

    This report presents the results of measurements of dosimetric properties of simple extremity phantoms suitable for use in extremity dosimeter performance testing. Two sizes of phantoms were used in this study. One size represented the forearm or lower leg and the other size represented the finger or toe. For both phantom sizes, measurements were performed on solid plastic phantoms and on phantoms containing simulated bone material to determine the effect of backscattered radiations from the bone on the surface dose. Exposure-to-dose conversion factors (C/sub x/ factors) were determined for photon energies ranging from 16 to 1250 keV (average for 60 Co). The effect of the presence of a phantom was also measured for a 90 Sr/ 90 Y source. Significant differences in the measured C/sub x/ factors were found among the phantoms investigated. The factors for the finger-sized phantoms were uniformly less than for the arm-sized phantoms

  11. Benchmark calculations with simple phantom for neutron dosimetry (2)

    International Nuclear Information System (INIS)

    Yukio, Sakamoto; Shuichi, Tsuda; Tatsuhiko, Sato; Nobuaki, Yoshizawa; Hideo, Hirayama

    2004-01-01

    Benchmark calculations for high-energy neutron dosimetry were undertaken after SATIF-5. Energy deposition in a cylindrical phantom with 100 cm radius and 30 cm depth was calculated for the irradiation of neutrons from 100 MeV to 10 GeV. Using the ICRU four-element loft tissue phantom and four single-element (hydrogen, carbon, nitrogen and oxygen) phantoms, the depth distributions of deposition energy and those total at the central region of phantoms within l cm radius and at the whole region of phantoms within 100 cm radius were calculated. The calculated results of FLUKA, MCNPX, MARS, HETC-3STEP and NMTC/JAM codes were compared. It was found that FLUKA, MARS and NMTC/JAM showed almost the same results. For the high-energy neutron incident, the MCNP-X results showed the largest ones in the total deposition energy and the HETC-3STEP results show'ed smallest ones. (author)

  12. Phantom limb phenomenon as an example of body image distortion

    Directory of Open Access Journals (Sweden)

    Razmus Magdalena

    2017-06-01

    Full Text Available Introduction: The perception of one’s own body, its mental representation, and emotional attitude to it are the components of so-called “body image” [1]. The aim of the research was to analyse phantom pain and non-painful phantom sensations as results of limb loss and to explain them in terms of body image distortion.

  13. Non-lethal heat treatment of cells results in reduction of tumor initiation and metastatic potential

    International Nuclear Information System (INIS)

    Kim, Yoo-Shin; Lee, Tae Hoon; O'Neill, Brian E.

    2015-01-01

    Non-lethal hyperthermia is used clinically as adjuvant treatment to radiation, with mixed results. Denaturation of protein during hyperthermia treatment is expected to synergize with radiation damage to cause cell cycle arrest and apoptosis. Alternatively, hyperthermia is known to cause tissue level changes in blood flow, increasing the oxygenation and radiosensitivity of often hypoxic tumors. In this study, we elucidate a third possibility, that hyperthermia alters cellular adhesion and mechanotransduction, with particular impact on the cancer stem cell population. We demonstrate that cell heating results in a robust but temporary loss of cancer cell aggressiveness and metastatic potential in mouse models. In vitro, this heating results in a temporary loss in cell mobility, adhesion, and proliferation. Our hypothesis is that the loss of cellular adhesion results in suppression of cancer stem cells and loss of tumor virulence and metastatic potential. Our study suggests that the metastatic potential of cancer is particularly reduced by the effects of heat on cellular adhesion and mechanotransduction. If true, this could help explain both the successes and failures of clinical hyperthermia, and suggest ways to target treatments to those who would most benefit. - Highlights: • Non-lethal hyperthermia treatment of cancer cells is shown to cause a reduction in rates of tumor initiation and metastasis. • Dynamic imaging of cells during heat treatment shows temporary changes in cell shape, cell migration, and cell proliferation. • Loss of adhesion may lead to the observed effect, which may disproportionately impact the tumor initiating cell fraction. • Loss or suppression of the tumor initiating cell fraction results in the observed loss of metastatic potential in vivo. • This result may lead to new approaches to synergizing hyperthermia with surgery, radiation, and chemotherapy

  14. Non-lethal heat treatment of cells results in reduction of tumor initiation and metastatic potential

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoo-Shin; Lee, Tae Hoon; O' Neill, Brian E., E-mail: BEOneill@houstonmethodist.org

    2015-08-14

    Non-lethal hyperthermia is used clinically as adjuvant treatment to radiation, with mixed results. Denaturation of protein during hyperthermia treatment is expected to synergize with radiation damage to cause cell cycle arrest and apoptosis. Alternatively, hyperthermia is known to cause tissue level changes in blood flow, increasing the oxygenation and radiosensitivity of often hypoxic tumors. In this study, we elucidate a third possibility, that hyperthermia alters cellular adhesion and mechanotransduction, with particular impact on the cancer stem cell population. We demonstrate that cell heating results in a robust but temporary loss of cancer cell aggressiveness and metastatic potential in mouse models. In vitro, this heating results in a temporary loss in cell mobility, adhesion, and proliferation. Our hypothesis is that the loss of cellular adhesion results in suppression of cancer stem cells and loss of tumor virulence and metastatic potential. Our study suggests that the metastatic potential of cancer is particularly reduced by the effects of heat on cellular adhesion and mechanotransduction. If true, this could help explain both the successes and failures of clinical hyperthermia, and suggest ways to target treatments to those who would most benefit. - Highlights: • Non-lethal hyperthermia treatment of cancer cells is shown to cause a reduction in rates of tumor initiation and metastasis. • Dynamic imaging of cells during heat treatment shows temporary changes in cell shape, cell migration, and cell proliferation. • Loss of adhesion may lead to the observed effect, which may disproportionately impact the tumor initiating cell fraction. • Loss or suppression of the tumor initiating cell fraction results in the observed loss of metastatic potential in vivo. • This result may lead to new approaches to synergizing hyperthermia with surgery, radiation, and chemotherapy.

  15. Development, calibration and experimental results obtained with an innovative calorimeter (CALMOS) for nuclear heating measurements

    International Nuclear Information System (INIS)

    Carcreff, H.; Cloute-Cazalaa, V.; Salmon, L.

    2011-01-01

    Nuclear heating inside an MTR reactor has to be known in order to be able to control samples temperature during irradiation experiments. An R and D program has been carried out at CEA to design a new type of in-core calorimetric system. This new development, started in 2002, has for main objective to manufacture a calorimeter suitable to monitoring nuclear heating inside the 70 MWth OSIRIS material testing reactor operated by CEA's Nuclear Energy Div. at the Saclay research center. An innovative calorimetric probe, associated to a specific handling system, has been designed to provide access to measurements both along the fissile height and on the upper part of the core, where nuclear heating still remains high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for process validation, while a displacement system has been especially studied to move the probe along a given axial measurement range. This paper deals with the development, tests on preliminary mock-ups and the finalization of the probe. Main modeling and experimental results are presented. Moreover, alternative methods to calibration for nuclear heating rate measurements which are now possible with this new calorimeter are presented and discussed. (authors)

  16. Development, calibration, and experimental results obtained with an innovative calorimeter (CALMOS) for nuclear heating measurements

    International Nuclear Information System (INIS)

    Carcreff, Hubert; Cloute-Cazalaa, Veronique; Salmon, Laurent

    2012-01-01

    Nuclear heating inside an MTR reactor has to be known in order to be able to control samples temperature during irradiation experiments. An R and D program has been carried out at CEA to design a new type of in-core calorimetric system. This new development, started in 2002, has for main objective to manufacture a calorimeter suitable to monitoring nuclear heating inside the 70 MWth OSIRIS material testing reactor operated by CEA's Nuclear Energy Division at the Saclay research center. An innovative calorimetric probe, associated to a specific handling system, has been designed to provide access to measurements both along the fissile height and on the upper part of the core, where nuclear heating still remains high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for process validation, while a displacement system has been especially studied to move the probe along a given axial measurement range. This paper deals with the development, tests on preliminary mock-ups and the finalization of the probe. Main modeling and experimental results are presented. Moreover, alternative methods to calibration for nuclear heating rate measurements which are now possible with this new calorimeter are presented and discussed. (authors)

  17. High heat flux actively cooled plasma facing components development, realization and first results in Tore Supra

    International Nuclear Information System (INIS)

    Grosman, A.

    2004-01-01

    The development, design, manufacture and testing of actively cooled high heat flux plasma facing components (PFC) has been an essential stage towards long powerful tokamak operations for Tore-Supra, it lasted about 10 years. This paper deals with the toroidal pumped limiter (TPL) that is able to sustain up to 10 MW/m 2 of nominal heat flux. This device is based on hardened copper alloy heat sink structures covered by a carbon fiber composite armour, it resulted in the manufacturing of 600 elementary components, called finger elements, to achieve the 7.6 m 2 TPL. This assembly has been operating in Tore-Supra since spring 2002. Some difficulties occurred during the manufacturing phase, the valuable industrial experience is summarized in the section 2. The permanent monitoring of PFC surface temperature all along the discharge is performed by a set of 6 actively cooled infrared endoscopes. The heat flux monitoring and control issue but also the progress made in our understanding of the deuterium retention in long discharges are described in the section 3. (A.C.)

  18. High heat flux actively cooled plasma facing components development, realization and first results in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Grosman, A. [Association Euratom-CEA, Centre d' Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    2004-07-01

    The development, design, manufacture and testing of actively cooled high heat flux plasma facing components (PFC) has been an essential stage towards long powerful tokamak operations for Tore-Supra, it lasted about 10 years. This paper deals with the toroidal pumped limiter (TPL) that is able to sustain up to 10 MW/m{sup 2} of nominal heat flux. This device is based on hardened copper alloy heat sink structures covered by a carbon fiber composite armour, it resulted in the manufacturing of 600 elementary components, called finger elements, to achieve the 7.6 m{sup 2} TPL. This assembly has been operating in Tore-Supra since spring 2002. Some difficulties occurred during the manufacturing phase, the valuable industrial experience is summarized in the section 2. The permanent monitoring of PFC surface temperature all along the discharge is performed by a set of 6 actively cooled infrared endoscopes. The heat flux monitoring and control issue but also the progress made in our understanding of the deuterium retention in long discharges are described in the section 3. (A.C.)

  19. The subresolution DaTSCAN phantom: a cost-effective, flexible alternative to traditional phantom technology.

    Science.gov (United States)

    Taylor, Jonathan C; Vennart, Nicholas; Negus, Ian; Holmes, Robin; Bandmann, Oliver; Lo, Christine; Fenner, John

    2018-03-01

    The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer. The paper sheets and attenuating slabs are interleaved before scanning. Use of thin layers ensures that they cannot be individually resolved on reconstructed images. An investigation was carried out to demonstrate the performance of such a phantom in producing simplified I-FP-CIT uptake patterns. Single photon emission computed tomography imaging was carried out on an assembled phantom designed to mimic a healthy patient. Striatal binding ratio results and linear striatal dimensions were calculated from the reconstructed data and compared with that of 22 clinical patients without evidence of Parkinsonian syndrome, determined from clinical follow-up. Striatal binding ratio results for the fully assembled phantom were: 3.1, 3.3, 2.9 and 2.6 for the right caudate, left caudate, right putamen and right caudate, respectively. All were within two SDs of results derived from a cohort of clinical patients. Medial-lateral and anterior-posterior dimensions of the simulated striata were also within the range of values seen in clinical data. This work provides the foundation for the generation of a range of more clinically realistic, physical phantoms.

  20. Nonlinear heat conduction equations with memory: Physical meaning and analytical results

    Science.gov (United States)

    Artale Harris, Pietro; Garra, Roberto

    2017-06-01

    We study nonlinear heat conduction equations with memory effects within the framework of the fractional calculus approach to the generalized Maxwell-Cattaneo law. Our main aim is to derive the governing equations of heat propagation, considering both the empirical temperature-dependence of the thermal conductivity coefficient (which introduces nonlinearity) and memory effects, according to the general theory of Gurtin and Pipkin of finite velocity thermal propagation with memory. In this framework, we consider in detail two different approaches to the generalized Maxwell-Cattaneo law, based on the application of long-tail Mittag-Leffler memory function and power law relaxation functions, leading to nonlinear time-fractional telegraph and wave-type equations. We also discuss some explicit analytical results to the model equations based on the generalized separating variable method and discuss their meaning in relation to some well-known results of the ordinary case.

  1. The results of the measurements of mass- and heat-transfer in the wet cooling tower

    International Nuclear Information System (INIS)

    Fabjan, Lj.; Gaspersic, B.

    1979-01-01

    These are the results of our investigations carried out on a packing inside a wet cooling tower for the purpose of studying the mass and heat transfer at the counterflow of water and humid air. The measurements on the experimental tower of the corresponding mathematical model reflect the average coefficient of mass and heat transfer for the unity of the active volume. Further the measurements of pressure drop at the air flow were carried out and thus the coefficient of aerodynamic losses were obtained. The results of measurements are given in the corresponding equations with the dimensionless numbers and diagrams. They will be of great use for the planning of new cooling towers. (author)

  2. Comparison of different phantoms used in digital diagnostic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bor, Dogan, E-mail: bor@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics. Tandogan, 06100 Ankara (Turkey); Unal, Elif, E-mail: elf.unall@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey); Uslu, Anil, E-mail: m.aniluslu@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey)

    2015-09-21

    The organs of extremity, chest, skull and lumbar were physically simulated using uniform PMMA slabs with different thicknesses alone and using these slabs together with aluminum plates and air gaps (ANSI Phantoms). The variation of entrance surface air kerma and scatter fraction with X-ray beam qualities was investigated for these phantoms and the results were compared with those measured from anthropomorphic phantoms. A flat panel digital radiographic system was used for all the experiments. Considerable variations of entrance surface air kermas were found for the same organs of different designs, and highest doses were measured for the PMMA slabs. A low contrast test tool and a contrast detail test object (CDRAD) were used together with each organ simulation of PMMA slabs and ANSI phantoms in order to test the clinical image qualities. Digital images of these phantom combinations and anthropomorphic phantoms were acquired in raw and clinically processed formats. Variation of image quality with kVp and post processing was evaluated using the numerical metrics of these test tools and measured contrast values from the anthropomorphic phantoms. Our results indicated that design of some phantoms may not be efficient enough to reveal the expected performance of the post processing algorithms.

  3. The impact of anthropometric patient-phantom matching on organ dose: A hybrid phantom study for fluoroscopy guided interventions

    International Nuclear Information System (INIS)

    Johnson, Perry B.; Geyer, Amy; Borrego, David; Ficarrotta, Kayla; Johnson, Kevin; Bolch, Wesley E.

    2011-01-01

    Purpose: To investigate the benefits and limitations of patient-phantom matching for determining organ dose during fluoroscopy guided interventions. Methods: In this study, 27 CT datasets representing patients of different sizes and genders were contoured and converted into patient-specific computational models. Each model was matched, based on height and weight, to computational phantoms selected from the UF hybrid patient-dependent series. In order to investigate the influence of phantom type on patient organ dose, Monte Carlo methods were used to simulate two cardiac projections (PA/left lateral) and two abdominal projections (RAO/LPO). Organ dose conversion coefficients were then calculated for each patient-specific and patient-dependent phantom and also for a reference stylized and reference hybrid phantom. The coefficients were subsequently analyzed for any correlation between patient-specificity and the accuracy of the dose estimate. Accuracy was quantified by calculating an absolute percent difference using the patient-specific dose conversion coefficients as the reference. Results: Patient-phantom matching was shown most beneficial for estimating the dose to heavy patients. In these cases, the improvement over using a reference stylized phantom ranged from approximately 50% to 120% for abdominal projections and for a reference hybrid phantom from 20% to 60% for all projections. For lighter individuals, patient-phantom matching was clearly superior to using a reference stylized phantom, but not significantly better than using a reference hybrid phantom for certain fields and projections. Conclusions: The results indicate two sources of error when patients are matched with phantoms: Anatomical error, which is inherent due to differences in organ size and location, and error attributed to differences in the total soft tissue attenuation. For small patients, differences in soft tissue attenuation are minimal and are exceeded by inherent anatomical differences

  4. Development of a phantom to test fully automated breast density software – A work in progress

    International Nuclear Information System (INIS)

    Waade, G.G.; Hofvind, S.; Thompson, J.D.; Highnam, R.; Hogg, P.

    2017-01-01

    Objectives: Mammographic density (MD) is an independent risk factor for breast cancer and may have a future role for stratified screening. Automated software can estimate MD but the relationship between breast thickness reduction and MD is not fully understood. Our aim is to develop a deformable breast phantom to assess automated density software and the impact of breast thickness reduction on MD. Methods: Several different configurations of poly vinyl alcohol (PVAL) phantoms were created. Three methods were used to estimate their density. Raw image data of mammographic images were processed using Volpara to estimate volumetric breast density (VBD%); Hounsfield units (HU) were measured on CT images; and physical density (g/cm 3 ) was calculated using a formula involving mass and volume. Phantom volume versus contact area and phantom volume versus phantom thickness was compared to values of real breasts. Results: Volpara recognized all deformable phantoms as female breasts. However, reducing the phantom thickness caused a change in phantom density and the phantoms were not able to tolerate same level of compression and thickness reduction experienced by female breasts during mammography. Conclusion: Our results are promising as all phantoms resulted in valid data for automated breast density measurement. Further work should be conducted on PVAL and other materials to produce deformable phantoms that mimic female breast structure and density with the ability of being compressed to the same level as female breasts. Advances in knowledge: We are the first group to have produced deformable phantoms that are recognized as breasts by Volpara software. - Highlights: • Several phantoms of different configurations were created. • Three methods to assess phantom density were implemented. • All phantoms were identified as breasts by the Volpara software. • Reducing phantom thickness caused a change in phantom density.

  5. IMRT delivery verification using a spiral phantom

    International Nuclear Information System (INIS)

    Richardson, Susan L.; Tome, Wolfgang A.; Orton, Nigel P.; McNutt, Todd R.; Paliwal, Bhudatt R.

    2003-01-01

    In this paper we report on the testing and verification of a system for IMRT delivery quality assurance that uses a cylindrical solid water phantom with a spiral trajectory for radiographic film placement. This spiral film technique provides more complete dosimetric verification of the entire IMRT treatment than perpendicular film methods, since it samples a three-dimensional dose subspace rather than using measurements at only one or two depths. As an example, the complete analysis of the predicted and measured spiral films is described for an intracranial IMRT treatment case. The results of this analysis are compared to those of a single field perpendicular film technique that is typically used for IMRT QA. The comparison demonstrates that both methods result in a dosimetric error within a clinical tolerance of 5%, however the spiral phantom QA technique provides a more complete dosimetric verification while being less time consuming. To independently verify the dosimetry obtained with the spiral film, the same IMRT treatment was delivered to a similar phantom in which LiF thermoluminescent dosimeters were arranged along the spiral trajectory. The maximum difference between the predicted and measured TLD data for the 1.8 Gy fraction was 0.06 Gy for a TLD located in a high dose gradient region. This further validates the ability of the spiral phantom QA process to accurately verify delivery of an IMRT plan

  6. Image fusion tool: Validation by phantom measurements

    International Nuclear Information System (INIS)

    Zander, A.; Geworski, L.; Richter, M.; Ivancevic, V.; Munz, D.L.; Muehler, M.; Ditt, H.

    2002-01-01

    Aim: Validation of a new image fusion tool with regard to handling, application in a clinical environment and fusion precision under different acquisition and registration settings. Methods: The image fusion tool investigated allows fusion of imaging modalities such as PET, CT, MRI. In order to investigate fusion precision, PET and MRI measurements were performed using a cylinder and a body contour-shaped phantom. The cylinder phantom (diameter and length 20 cm each) contained spheres (10 to 40 mm in diameter) which represented 'cold' or 'hot' lesions in PET measurements. The body contour-shaped phantom was equipped with a heart model containing two 'cold' lesions. Measurements were done with and without four external markers placed on the phantoms. The markers were made of plexiglass (2 cm diameter and 1 cm thickness) and contained a Ga-Ge-68 core for PET and Vitamin E for MRI measurements. Comparison of fusion results with and without markers was done visually and by computer assistance. This algorithm was applied to the different fusion parameters and phantoms. Results: Image fusion of PET and MRI data without external markers yielded a measured error of 0 resulting in a shift at the matrix border of 1.5 mm. Conclusion: The image fusion tool investigated allows a precise fusion of PET and MRI data with a translation error acceptable for clinical use. The error is further minimized by using external markers, especially in the case of missing anatomical orientation. Using PET the registration error depends almost only on the low resolution of the data

  7. Oscillating-flow loss test results in rectangular heat exchanger passages

    Science.gov (United States)

    Wood, J. Gary

    1991-01-01

    Test results of oscillating flow losses in rectangular heat exchanger passages of various aspect ratios are given. This work was performed in support of the design of a free-piston Stirling engine (FPSE) for a dynamic space power conversion system. Oscillating flow loss testing was performed using an oscillating flow rig, which was based on a variable stroke and variable frequency linear drive motor. Tests were run over a range of oscillating flow parameters encompassing the flow regimes of the proposed engine design. Test results are presented in both tabular and graphical form and are compared against analytical predictions.

  8. 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.

  9. Alderson-Rando phantom 'voxelization' for use in numerical dosimetry

    International Nuclear Information System (INIS)

    Santos, A.M.; Vieira, J.W.

    2008-01-01

    This paper presents the methodology used for creating a voxel phantom from the tomographic physical Alderson-Rando phantom images (HR) and to develop a computer model formed by exposure of the resulting phantom 'voxelization' of AR coupled to the Monte Carlo code EGS4 plus algorithms to simulate radioactive sources in internal dosimetry

  10. A paper sheet phantom for scintigraphic planar imaging. Usefulness of pouch-laminated paper source

    International Nuclear Information System (INIS)

    Takaki, Akihiro; Soma, Tsutomu; Murase, Kenya; Teraoka, Satomi; Murakami, Tomonori; Kojima, Akihiro; Matsumoto, Masanori

    2007-01-01

    In order to perform experimental measurements for evaluation of imaging device's performance, data acquisition technique, and clinical images on scintigraphic imaging, many kinds of phantoms are employed. However, since these materials are acrylic and plastic, the thickness and quality of those materials cause attenuation and scatter in itself. We developed a paper sheet phantom sealed with a pouch laminator, which can be a true radioactive source in air. In this study, the paper sheet phantom was compared to the acrylic liver phantom, with the thickness of 2 cm, which is commercially available. The results showed that although some scatter counts were contained within the image of the acrylic liver phantom, there were few scattered photons in the paper sheet phantom image. Furthermore, this laminated paper sheet phantom made handling of the source and its waste easier. If the paper sheet phantom will be designed more sophisticatedly, it becomes a useful tool for planar imaging experiments. (author)

  11. 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)

  12. First results of out-of-pile experiments concerning cooling phenomena of molten layers with internal heat sources

    International Nuclear Information System (INIS)

    Fieg, G.

    1977-01-01

    After severe hypothetical reactor accidents, large amounts of molten core material with internal heat generation may appear. It must be guaranteed that these materials can be kept within the containment. To clarify this situation, the knowledge of heat transport from liquid layers with internal heat generation is needed. First experimental results on heat transport from internally heated horizontal fluid layers are presented. The experiments have been performed in a smooth horizontal vessel with the base of 15 x 15 cm 2 . The Joule-heated liquid layer (depth L = 1 cm - 3.5 cm) is enclosed between two isothermal horizontal walls. They are polished fore parts of heat exchangers. The temperatures of the walls were held constant with thermostatically controlled water circulating through the heat exchangers. Horizontal heat fluxes were depressed by appropriate insulation of the side walls. The total heat transport to the upper and lower boundaries has been measured by the mass transport through the heat exchangers and the temperature rise of the cooling water

  13. Roles of Urban Tree Canopy and Buildings in Urban Heat Island Effects: Parameterization and Preliminary Results

    Science.gov (United States)

    Loughner, Christopher P.; Allen, Dale J.; Zhang, Da-Lin; Pickering, Kenneth E.; Dickerson, Russell R.; Landry, Laura

    2012-01-01

    Urban heat island (UHI) effects can strengthen heat waves and air pollution episodes. In this study, the dampening impact of urban trees on the UHI during an extreme heat wave in the Washington, D.C., and Baltimore, Maryland, metropolitan area is examined by incorporating trees, soil, and grass into the coupled Weather Research and Forecasting model and an urban canopy model (WRF-UCM). By parameterizing the effects of these natural surfaces alongside roadways and buildings, the modified WRF-UCM is used to investigate how urban trees, soil, and grass dampen the UHI. The modified model was run with 50% tree cover over urban roads and a 10% decrease in the width of urban streets to make space for soil and grass alongside the roads and buildings. Results show that, averaged over all urban areas, the added vegetation decreases surface air temperature in urban street canyons by 4.1 K and road-surface and building-wall temperatures by 15.4 and 8.9 K, respectively, as a result of tree shading and evapotranspiration. These temperature changes propagate downwind and alter the temperature gradient associated with the Chesapeake Bay breeze and, therefore, alter the strength of the bay breeze. The impact of building height on the UHI shows that decreasing commercial building heights by 8 m and residential building heights by 2.5 m results in up to 0.4-K higher daytime surface and near-surface air temperatures because of less building shading and up to 1.2-K lower nighttime temperatures because of less longwave radiative trapping in urban street canyons.

  14. Experimental results for hydrocarbon refrigerant vaporization inside brazed plate heat exchangers at high pressure

    DEFF Research Database (Denmark)

    Desideri, Adriano; Ommen, Torben Schmidt; Wronski, Jorrit

    2016-01-01

    fluids at typical working conditions of ORC systems for low temperature waste heat recovery (WHR) applications. Based on these premises, a novel testrig has been recently designed and built at the Technical University of Denmark to simulate the evaporating condition occurring in a small capacity ORC...... power unit. In this contribution the preliminary experimental results obtained from the first experimental campaign carried out on the rig are reported. HFC-134a was selected as working fluid. The experiments were carried out at saturation temperature of 60, 70 and 80 °C and inlet and outlet qualities...

  15. 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 ...

  16. Effect of insertion depth on helical antenna performance in a muscle-equivalent phantom

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, J W; Meeson, S; Birch, M J [Department of Clinical Physics, Royal London Hospital, 56-76 Ashfield Street, London, E1 1BB (United Kingdom)

    2005-06-21

    Barrett's oesophagus is considered to increase the risk of cancer 30 fold. A set of helical microwave antennas was designed to investigate their potential use in the thermal therapy of Barrett's oesophagus. For treatment, a balloon filled with muscle-equivalent material encapsulates the antenna. The effects of insertion depth and coil-spacing on the thermal distribution produced by the antennas (20-35 mm) were characterized. The 35 mm helical antenna, with a coil-spacing of 3.6 mm resulted in uniform heating for an insertion depth of 40 mm. It was observed that the resultant temperature distribution produced, by the antennas, was dependent on the insertion depth within the phantom. For all antennas studied, deeper insertion resulted in two high intensity regions, approximately 1/4 and 3/4 along the antenna length. In contrast, shallow insertion resulted in predominant tip heating with undesirable heating at the phantom entry point. However, by manipulating the coil-spacing of the helix, uniform temperature profiles were achieved for a range of insertion depths.

  17. Efficiency factors for Phoswich based lung monitor using ICRP Voxel phantoms

    International Nuclear Information System (INIS)

    Manohari, M.; Mathiyarasu, R.; Rajagopal, V.; Jose, M.T.; Venkatraman, B.

    2016-01-01

    The actinide contamination in lungs is measured either using array of HPGe detector or Phoswich based lung monitors. This paper discusses the results obtained during numerical calibration of Phoswich based lung counting system using ICRP VOXEL phantoms. The results are also compared with measured efficiency values obtained using LLNL phantom. The efficiency factors of 241 Am present in the lungs for phoswich detector was simulated using ICRP male voxel phantom and compared with experimentally observed values using LLNL Phantom. The observed deviation is 12%. The efficiency of the same for female subjects was estimated using ICRP female voxel phantom for both supine and posterior geometries

  18. Preliminary results from the Arecibo Heating Experiment (HEX): HF to GNSS

    Science.gov (United States)

    Jackson-Booth, N.; Penney, R.; Bernhardt, P. A.; Martin, P. L.; Buckland, R.; Morton-Orr, T.; Nossa, E.; Buckland, R.

    2017-12-01

    The ionosphere is subject to many solar and terrestrial influences that can generate disturbances, causing degradation to modern communication and navigational systems. Whilst the disturbances are normally caused by natural phenomena such as hurricanes, earthquakes and solar storms; they can also be generated by artificially modifying the ionosphere. Artificial Ionospheric Modification (AIM) attempts to alter a small region of the ionosphere in order to perturb the RF propagation environment. This can be achieved through injecting the ionosphere with aerosols, chemicals or radio signals. The effects of any such modification can be detected through the deployment of sensors, including ground based high-frequency (HF) sounders and dual-band Global Navigation Satellite System (GNSS) receivers. HF sounders allow measurements of the bottom-side of the ionosphere. GNSS receivers offer a convenient means of obtaining information about the ionosphere, including ionospheric disturbances through changes in the derived total electron content information. The Heating EXperiment (HEX), which took place in March and May 2017, was designed to further our understanding of the phenomena caused by artificially heating a small region of the ionosphere, using the Arecibo facility in Puerto Rico. This was achieved by utilizing a HF measurement experiment spread between Texas and Trinidad and the deployment of a small scale travelling ionospheric disturbance (TID) network near the heater. The TID network comprised three GNSS receivers along baselines of approximately 4 km, located 20 km north of the heater. This paper presents preliminary results from the HEX campaign, including evidence of heating-induced disturbances enhancing propagation between Virginia and Trinidad. The implications of generated irregularities on GNSS will also be discussed.

  19. Effect of degree of lipomobilization on results of glucose test in dairy cows in heat stress

    Directory of Open Access Journals (Sweden)

    Cincović M.R.

    2012-01-01

    Full Text Available Cows exposed to heat stress exhibit a decreased ability to mobilize lipids due to increased sensitivity to insulin, which is expressed in a decreased concentration of NEFA. However, certain cows can preserve the level of lipid mobilization after adapting to heat stress. We assumed that cows that have a preserved ability to mobilize lipids are less sensitive to insulin and that they have a lower tolerance for glucose. The aim of this work was to compare the results of an intravenous glucose tolerance test in cows that exhibited, in prolonged heat stress, a decreased (NEFA0.30 mmol/l ability for lipid mobilization. Glucose concentration and NEFA concentration were measured following intravenous application of glucose. The mean glycaemic index value did not differ statistically significantly between the two groups of cows at 10, 15 and 20 minutes after glucose application (p>0.05, but there was a tendency at 10 and 15 minutes for the glycaemia to be higher in cows with preserved lipomobilization (p<0.1. At 30, 60 and 90 minutes after glucose application, glycaemia was statistically significantly higher (p<0.01; p<0.05 and p<0.05 in the group of cows with preserved lipomobilization. The glycaemic index values (mmol/l shown in the same order (30, 60 and 90 minutes were as follows 9.91±0.21: 9.23±0.41; 5.41±0.5: 4.67±0.33 and 4.31±0.39: 3.47±0.37. The mean value for NEFA concentration in samples originating from the two experimental groups of cows did not differ statistically significantly following glucose application. The NEFA concentration showed a tendency to be higher in cows with preserved lipid mobilization in comparison with cows with decreased lipomobilization at 20 and 30 minutes after glucose application (p<0.1. Following the intravenous glucose tolerance test, NEFA and glucose concentrations were in a significant negative correlation, and that correlation was more expressed in cows with decreased lipomobilization. Cows with preserved

  20. Experimental results for an experimental condensation heat exchanger with a spiral minichanel tube. Comparison to numerical imulations

    Directory of Open Access Journals (Sweden)

    Hrubý J.

    2013-04-01

    Full Text Available The paper describes new results for an experimental heat exchanger equipped with a single corrugated capillary tube, basic information about the measurements and the experimental setup. Some of the results were compared with numerical simulations.

  1. Phantom shocks in patients with implantable cardioverter defibrillator

    DEFF Research Database (Denmark)

    Berg, Selina Kikkenborg; Moons, Philip; Zwisler, Ann-Dorthe

    2013-01-01

    of phantom shocks.METHODS AND RESULTS: The design was secondary explorative analyses of data from a randomized controlled trial. One hundred and ninety-six patients with first-time ICD implantation (79% male, mean age 58 years) were randomized (1 : 1) to either combined rehabilitation or a control group...... questions regarding the experience of phantom shocks, date, time, and place. Twelve patients (9.4%) experienced a phantom shock, 7 in the intervention group and 5 in the control group (NS). Neither age, sex, quality of life nor perceived health at baseline was significantly related to the probability...

  2. Evaluating the effectiveness of heat-resistant cast steel filtration from the results of structure examinations

    Directory of Open Access Journals (Sweden)

    Asłanowicz M.

    2007-01-01

    Full Text Available Filtration guarantees castings characterised by high quality and free from any non-metallic inclusions, which are formed at the stage of melting and pouring of liquid metal. This article discusses the problem of the effectiveness of filtration process taking as an example heat-resistant cast steel poured into ceramic moulds. In investigations, foamed zircon filters made by FerroTerm Sp. z o.o. The effectiveness of filtration was described and examined using the results of metallographic examinations, including macro- and micro-structure examinations of metal and of cast metal/ceramic filter interface, and measurements of the content of non-metallic inclusions. The methods of investigations were presented, the obtained results were described, and relevant conclusions were drawn, all of them unmistakably indicating a very beneficial effect that filtration has on molten metal quality. Łódź, Poland, were used.

  3. Test results for a heat-treated 4-cell 805 MHz superconducting cavity

    International Nuclear Information System (INIS)

    Rusnak, B.; Shapiro, A.H.

    1995-01-01

    Assessing superconducting technology for potential upgrades to existing proton accelerators as well as applications to future high-current machines necessitates developing expertise in the processing and handling of multicell cavities at useful frequencies. In order to address some of these technological issues, Los Alamos has purchased a 4-cell 805-MHz superconducting cavity from Siemens AG. The individual cavity cells were double-sided titanium heat-treated after equatorial welding, then the irises were welded to complete the cavity assembly. The resulting high RRR (residual resistance ratio) in the cells enables stable operation at higher cavity field levels than are possible with lower RRR material. Additionally, the high thermal conductivity of the material is conducive to rf and high peak power processing. The cavity was also cleaned at Los Alamos with high-pressure water rinsing. Results from the initial cavity tests, utilizing various processing techniques, are presented

  4. Hubungan Phantom Vibration Syndrome Terhadap Sleep Disorder dan Kondisi Stress

    Directory of Open Access Journals (Sweden)

    Ajeng Yeni Setianingrum

    2017-10-01

    Full Text Available Phantom vibration syndrome is a condition where a person would feel the sensation of vibration of a cell phone as if there were incoming notification but the fact is not. This research investigated the relationship between phantom vibration syndromes, sleep disorder and stress condition. Questionnaires were distributed to 120 participants with age range 18 to 23 years old. Data of participants showed that all of participants using a smart mobile phone and 24% of them have more than one cell phone. Time usage of cell phone is at least 1 hour. 23% of participants using a cell phone for social media activity, followed by 21% related to entertainment (music, video and games. The results showed a positive relationship between phantom vibration syndrome, sleep disorder and stress condition. Insomnia contributed a greater influence on stress condition. However, the phantom vibration syndrome is more directly affecting the sleep apnea compared to insomnia and stress condition. Therefore, the phantom vibration syndrome more affects stress condition indirectly, through sleep disorder (sleep apnea and insomnia. Consequently, phantom vibration syndrome has a strong relationship with stress condition at the time of the phantom vibration syndrome can cause sleep disorder.

  5. PCM-air heat exchangers for free-cooling applications in buildings: Experimental results of two real-scale prototypes

    International Nuclear Information System (INIS)

    Lazaro, Ana; Dolado, Pablo; Marin, Jose M.; Zalba, Belen

    2009-01-01

    Latent heat storage using phase change materials (PCM) can be used for free-cooling. In this application low air temperature is used to solidify the PCM during the night and then during the next day, the inside air of a building can be cooled down by exchanging heat with PCM. Short times for charging and discharging the PCM are required. PCM have in general low thermal conductivity, therefore the heat exchanger design is very important to fulfil free-cooling requirements. This paper presents an experimental setup for testing PCM-air real-scale heat exchangers and the results for two real-scale prototypes. Results show that a heat exchanger using a PCM with lower thermal conductivity and lower total stored energy, but adequately designed, has higher cooling power and can be applied for free-cooling

  6. Summary of results from sodium-heated steam generator test program

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, J S

    1975-07-01

    A 28 MWt sodium-heated steam generator test unit developed and fabricated by Atomics International was operated in the Sodium Component Test Installation. The SCTI is located at the Liquid Metal Engineering Center which is operated for the Atomic Energy Commission by Atomics International, Reviewed in this paper are the results of the test operations and the findings of the post-test examination of the module. Testing was performed to assure the mechanical integrity of the unit over a wide range of simulated plant operating conditions and to develop a variety of performance data. Specific tests conducted included preheat, vibration, startup-shutdown, pressurization, steady state and parametric performance mapping, endurance, simulated leak injection, low- flow stability and simulated plant transients. (author)

  7. Photoacoustic microscopy of bilirubin in tissue phantoms

    Science.gov (United States)

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

    2012-12-01

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

  8. New mechanism to cross the phantom divide

    International Nuclear Information System (INIS)

    Du, Yunshuang; Zhang, Hongsheng; Li, Xin-Zhou

    2011-01-01

    Recently, type Ia supernova data appear to support a dark energy whose equation of state w crosses -1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the equation of state to cross the phantom divide by a scalar field in gravity with an additional inverse power-law term of the Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the phantom divide is obtained. Some analytical solutions with w -1 are obtained. A minimally coupled scalar with different potentials, including quadratic, cubic, quantic, exponential and logarithmic potentials are investigated via numerical methods, respectively. All these potentials lead to the crossing behavior. We show that it is a robust result which is hardly dependent on the concrete form of the potential of the scalar. (orig.)

  9. Solar assisted conditioning of residences with floor heating and ceiling cooling: review and simulation results

    OpenAIRE

    Egrican, Nilufer; Korkmaz, Adnan

    2015-01-01

    Solar or solar assisted heating and cooling systems are becoming widespread to reduce CO2 emissions. Efficient radiant space heating and cooling systems can be used to decrease the energy bills and improve occupant thermal comfort in buildings. This study uses the TRNSYS program, for the modeling and simulation of solar assisted radiant heating and cooling of a building with the domestic hot water supply, to examine the effects of various parameters on energy consumption. Calculations are per...

  10. Experimental Results For Hydrocarbon Refrigerant Vaporization In Brazed Plate Heat Exchangers at High Pressure

    OpenAIRE

    Desideri, Adriano; Schmidt Ommen, Torben; Wronski, Jorrit; Quoilin, Sylvain; Lemort, Vincent; Haglind, Fredrik

    2016-01-01

    In this contribution, the experimental heat transfer coefficient  and the pressure drop measured during HFC refrigerants vaporization inside small brazed plate heat exchanger (PHE) at typical evaporation temperature for organic Rankine cycle systems for low thermal energy quality applications are presented. Scientific work focusing on the heat transfer in PHEs has been carried out since the late 19th century. More recent publications have been focusing on vaporization and condensation of ref...

  11. Experimental results for hydrocarbon refrigerant vaporization in brazed plate heat exchangers at high pressure

    OpenAIRE

    Desideri, Adriano; Rhyl Kaern, Martin; Ommen Schmidt, Torben; Wronski, Jorrit; Quoilin, Sylvain; Lemort, Vincent; Haglind, Fredrik

    2016-01-01

    In recent years the interest in small capacity organic Rankine cycle (ORC) power systems for harvesting low quality waste thermal energy from industrial processes has been steadily growing. Micro ORC systems are normally equipped with brazed plate heat exchangers which allows for efficient heat transfer with a compact design. An accurate prediction of the heat transfer process characterizing these devices is required from the design phase to the development of model- based control strategies....

  12. Design of a tracked ultrasound calibration phantom made of LEGO bricks

    Science.gov (United States)

    Walsh, Ryan; Soehl, Marie; Rankin, Adam; Lasso, Andras; Fichtinger, Gabor

    2014-03-01

    PURPOSE: Spatial calibration of tracked ultrasound systems is commonly performed using precisely fabricated phantoms. Machining or 3D printing has relatively high cost and not easily available. Moreover, the possibilities for modifying the phantoms are very limited. Our goal was to find a method to construct a calibration phantom from affordable, widely available components, which can be built in short time, can be easily modified, and provides comparable accuracy to the existing solutions. METHODS: We designed an N-wire calibration phantom made of LEGO® bricks. To affirm the phantom's reproducibility and build time, ten builds were done by first-time users. The phantoms were used for a tracked ultrasound calibration by an experienced user. The success of each user's build was determined by the lowest root mean square (RMS) wire reprojection error of three calibrations. The accuracy and variance of calibrations were evaluated for the calibrations produced for various tracked ultrasound probes. The proposed model was compared to two of the currently available phantom models for both electromagnetic and optical tracking. RESULTS: The phantom was successfully built by all ten first-time users in an average time of 18.8 minutes. It cost approximately $10 CAD for the required LEGO® bricks and averaged a 0.69mm of error in the calibration reproducibility for ultrasound calibrations. It is one third the cost of similar 3D printed phantoms and takes much less time to build. The proposed phantom's image reprojections were 0.13mm more erroneous than those of the highest performing current phantom model The average standard deviation of multiple 3D image reprojections differed by 0.05mm between the phantoms CONCLUSION: It was found that the phantom could be built in less time, was one third the cost, compared to similar 3D printed models. The proposed phantom was found to be capable of producing equivalent calibrations to 3D printed phantoms.

  13. Effectiveness of quantitative MAA SPECT/CT for the definition of vascularized hepatic volume and dosimetric approach: phantom validation and clinical preliminary results in patients with complex hepatic vascularization treated with yttrium-90-labeled microspheres.

    Science.gov (United States)

    Garin, Etienne; Lenoir, Laurence; Rolland, Yan; Laffont, Sophie; Pracht, Marc; Mesbah, Habiba; Porée, Philippe; Ardisson, Valérie; Bourguet, Patrick; Clement, Bruno; Boucher, Eveline

    2011-12-01

    The goal of this study was to assess the use of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) analysis for vascularized volume measurements in the use of the yttrium-90-radiolabeled microspheres (TheraSphere). A phantom study was conducted for the validation of SPECT/CT volume measurement. SPECT/CT quantitative analysis was used for the measurement of the volume of distribution of the albumin macroaggregates (MAA; i.e., the vascularized volume) in the liver and the tumor, and the total activity contained in the liver and the tumor in four consecutive patients presenting with a complex liver vascularization referred for a treatment with TheraSphere. SPECT/CT volume measurement proved to be accurate (mean error <7%) and reproducible (interobserver concordance 0.99). For eight treatments, in cases of complex hepatic vascularization, the hepatic volumes based on angiography and CT led to a relative overestimation or underestimation of the vascularized hepatic volume by 43.2 ± 32.7% (5-87%) compared with SPECT/CT analyses. The vascularized liver volume taken into account calculated from SPECT/CT data, instead of angiography and CT data, results in modifying the activity injected for three treatments of eight. Moreover, quantitative analysis of SPECT/CT allows us to calculate the absorbed dose in the tumor and in the healthy liver, leading to doubling of the injected activity for one treatment of eight. MAA SPECT/CT is accurate for volume measurements. It provides a valuable contribution to the therapeutic planning of patients presenting with complex hepatic vascularization, in particular for calculating the vascularized liver volume, the activity to be injected and the absorbed doses. Studies should be conducted to assess the role of quantitative MAA/SPECT CT in therapeutic planning.

  14. 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)

  15. 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.

  16. 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)

  17. 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.

  18. 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)

  19. The Consequences of Unpredictable Development of Economic Conditions on Heat Exchanger Network Configurations and Economic Results

    DEFF Research Database (Denmark)

    Mou, C.; Qvale, Einar Bjørn

    2002-01-01

    streams. The primary objective of the present work was to gain an understanding of the influence of dramatic economic changes on heat exchanger network (HEN) configurations, their profitability and how an existing HEN could restrict future possibilities of heat recovery. HENs were designed to maximise...

  20. Full-scale and time-scale heating experiments at Stripa: preliminary results

    International Nuclear Information System (INIS)

    Cook, N.G.W.; Hood, Michael; California Univ., Berkeley

    1978-01-01

    Two full-scale heating experiments and a time-scale heating experiment have recently been started in granite 340 meters below surface. The purpose of the full-scale heating experiments is to assess the near-field effects of thermal loading for the design of an underground repository of nuclear wastes. That of the time-scale heating experiments is to obtain field data of the interaction between heaters and its effect on the rock mass during a period of about two years, which corresponds to about twenty years of full-scale operation. Geological features of the rock around each experiment have been mapped carefully, and temperatures, stresses and displacements induced in the rock by heating have been calculated in advance of the experiments. Some 800 different measurements are recorded at frequent intervals by a computer system situated underground. These data can be compared at any time with predictions made earlier on video display units underground

  1. Determination of optimum filter in myocardial SPECT: A phantom study

    International Nuclear Information System (INIS)

    Takavar, A.; Shamsipour, Gh.; Sohrabi, M.; Eftekhari, M.

    2004-01-01

    Background: In myocardial perfusion SPECT images are degraded by photon attenuation, the distance-dependent collimator, detector response and photons scatter. Filters greatly affect quality of nuclear medicine images. Materials and Methods: A phantom simulating heart left ventricle was built. About 1mCi of 99m Tc was injected into the phantom. Images was taken from this phantom. Some filters including Parzen, Hamming, Hanning, Butter worth and Gaussian were exerted on the phantom images. By defining some criteria such as contrast, signal to noise ratio, and defect size detectability, the best filter can be determined. Results: 0.325 Nyquist frequency and 0.5 nq was obtained as the optimum cut off frequencies respectively for hamming and handing filters. Order 11, cut off 0.45 Nq and order 20 cut off 0.5 Nq obtained optimum respectively for Butter worth and Gaussian filters. Conclusion: The optimum member of every filter's family was obtained

  2. BOMAB phantom manufacturing quality assurance study using Monte Carlo computations

    International Nuclear Information System (INIS)

    Mallett, M.W.

    1994-01-01

    Monte Carlo calculations have been performed to assess the importance of and quantify quality assurance protocols in the manufacturing of the Bottle-Manikin-Absorption (BOMAB) phantom for calibrating in vivo measurement systems. The parameters characterizing the BOMAB phantom that were examined included height, fill volume, fill material density, wall thickness, and source concentration. Transport simulation was performed for monoenergetic photon sources of 0.200, 0.662, and 1,460 MeV. A linear response was observed in the photon current exiting the exterior surface of the BOMAB phantom due to variations in these parameters. Sensitivity studies were also performed for an in vivo system in operation at the Pacific Northwest Laboratories in Richland, WA. Variations in detector current for this in vivo system are reported for changes in the BOMAB phantom parameters studied here. Physical justifications for the observed results are also discussed

  3. Phantom dark ghost in Einstein-Cartan gravity

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Chiao [National Taiwan University, Department of Physics, Taipei (China); National Taiwan University, LeCosPA, Taipei (China); Bouhmadi-Lopez, Mariam [University of the Basque Country UPV/EHU, Department of Theoretical Physics, P.O. Box 644, Bilbao (Spain); Basque Foundation for Science, IKERBASQUE, Bilbao (Spain); Chen, Pisin [National Taiwan University, Department of Physics, Taipei (China); National Taiwan University, LeCosPA, Taipei (China); National Taiwan University, Graduate Institute of Astrophysics, Taipei (China); SLAC National Accelerator Laboratory, Stanford University, Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA (United States)

    2017-05-15

    A class of dynamical dark energy models is constructed through an extended version of fermion fields corresponding to phantom dark ghost spinors, which are spin 1/2 with mass dimension 1. We find that if these spinors interact with torsion fields in a homogeneous and isotropic universe, then it does not imply any future dark energy singularity or any abrupt event, though the fermion has a negative kinetic energy. In fact, the equation of state of this dark energy model will asymptotically approach the value w = -1 from above without crossing the phantom divide and inducing therefore a de Sitter state. Consequently, we expect the model to be stable because no real phantom fields will be created. At late time, the torsion fields will vanish as the corresponding phantom dark ghost spinors dilute. As would be expected, intuitively, this result is unaffected by the presence of cold dark matter although the proof is not as straightforward as in general relativity. (orig.)

  4. Development of phantom periapical for control quality

    International Nuclear Information System (INIS)

    Mendes, J.M.S.; Sales Junior, E.S.; Ferreira, F.C.L.; Paschoal, C.M.M.

    2015-01-01

    This study aimed to develop a dental phantom with cysts for evaluation of periapical radiographs that was tested in private dental offices in the city of Maraba, northern Brazil. Through some tests with the object simulator (phantom) were obtained 12 periapical radiographs (one in each of the offices visited) that waking up to the standards of Ordinance No. 453 were visually evaluated by observing the physical parameters of exposure (kVp and mA), time revelation of the radiographic film, later the other radiographs were visually compared with C6 ray set as the default. Among the results, it was found that only two of the twelve rays cysts could not be viewed and, therefore, these two images were deemed unsuitable for accurate diagnosis in the 10 images the cysts could be displayed, however according the images have different qualities comparisons. In addition, it can be concluded that the performance of the phantom was highly satisfactory showing to be efficient for use in quality control testing of dental X-rays, the quality control of radiographs and continuing education of dental professionals for a price much more accessible. (authors)

  5. Feasibility of salvage interstitial microwave thermal therapy for prostate carcinoma following failed brachytherapy: studies in a tissue equivalent phantom

    International Nuclear Information System (INIS)

    McCann, Claire; Kumaradas, J Carl; Gertner, Mark R; Davidson, Sean R H; Dolan, Alfred M; Sherar, Michael D

    2003-01-01

    Thermal therapy is an experimental treatment to destroy solid tumours by heating them to temperatures ranging from 55 deg C to 90 deg C, inducing thermal coagulation and necrosis of the tumour. We are investigating the feasibility of interstitial microwave thermal therapy as a salvage treatment for prostate cancer patients with local recurrence following failed brachytherapy. Due to the electrical and thermal conductivity of the brachytherapy seeds, we hypothesized that the seeds could scatter the microwave energy and cause unpredictable heating. To investigate this, a 915 MHz helical antenna was inserted into a muscle-equivalent phantom with and without brachytherapy seeds. Following a 10 W, 5 s input to the antenna, the temperature rise was used to calculate absorbed power, also referred to as specific absorption rate (SAR). Plane wave models based on Maxwell's equations were also used to characterize the electromagnetic scattering effect of the seeds. In addition, the phantom was heated with 8 W for 5 min to quantify the effect of the seeds on the temperature distribution during extended heating. SAR measurements indicated that the seeds had no significant effect on the shape and size of the SAR pattern of the antenna. However, the plane wave simulations indicated that the seeds could scatter the microwave energy resulting in hot spots at the seed edges. Lack of experimental evidence of these hot spots was probably due to the complex polarization of the microwaves emitted by the helical antenna. Extended heating experiments also demonstrated that the seeds had no significant effect on the temperature distributions and rates of temperature rise measured in the phantom. The results indicate that brachytherapy seeds are not a technical impediment to interstitial microwave thermal therapy as a salvage treatment following failed brachytherapy

  6. Test results from a helium gas-cooled porous metal heat exchanger

    International Nuclear Information System (INIS)

    North, M.T.; Rosenfeld, J.H.; Youchison, D.L.

    1996-01-01

    A helium-cooled porous metal heat exchanger was built and tested, which successfully absorbed heat fluxes exceeding all previously tested gas-cooled designs. Helium-cooled plasma-facing components are being evaluated for fusion applications. Helium is a favorable coolant for fusion devices because it is not a plasma contaminant, it is not easily activated, and it is easily removed from the device in the event of a leak. The main drawback of gas coolants is their relatively poor thermal transport properties. This limitation can be removed through use of a highly efficient heat exchanger design. A low flow resistance porous metal heat exchanger design was developed, based on the requirements for the Faraday shield for the International Thermonuclear Experimental Reactor (ITER) device. High heat flux tests were conducted on two representative test articles at the Plasma Materials Test Facility (PMTF) at Sandia National Laboratories. Absorbed heat fluxes as high as 40 MW/m 2 were successfully removed during these tests without failure of the devices. Commercial applications for electronics cooling and other high heat flux applications are being identified

  7. Design methodology and results evaluation of a heating functionality in modular lab-on-chip systems

    Science.gov (United States)

    Streit, Petra; Nestler, Joerg; Shaporin, Alexey; Graunitz, Jenny; Otto, Thomas

    2018-06-01

    Lab-on-a-chip (LoC) systems offer the opportunity of fast and customized biological analyses executed at the ‘point-of-need’ without expensive lab equipment. Some biological processes need a temperature treatment. Therefore, it is important to ensure a defined and stable temperature distribution in the biosensor area. An integrated heating functionality is realized with discrete resistive heating elements including temperature measurement. The focus of this contribution is a design methodology and evaluation technique of the temperature distribution in the biosensor area with regard to the thermal-electrical behaviour of the heat sources. Furthermore, a sophisticated control of the biosensor temperature is proposed. A finite element (FE) model with one and more integrated heat sources in a polymer-based LoC system is used to investigate the impact of the number and arrangement of heating elements on the temperature distribution around the heating elements and in the biosensor area. Based on this model, various LOC systems are designed and fabricated. Electrical characterization of the heat sources and independent temperature measurements with infrared technique are performed to verify the model parameters and prove the simulation approach. The FE model and the proposed methodology is the foundation for optimization and evaluation of new designs with regard to temperature requirements of the biosensor. Furthermore, a linear dependency of the heater temperature on the electric current is demonstrated in the targeted temperature range of 20 °C to 70 °C enabling the usage of the heating functionality for biological reactions requiring a steady-state temperature up to 70 °C. The correlation between heater and biosensor area temperature is derived for a direct control through the heating current.

  8. Liver phantom for quality control and training in nuclear medicine

    International Nuclear Information System (INIS)

    Lima Ferreira, Fernanda Carla; Nascimento Souza, Divanizia do

    2011-01-01

    In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256x256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

  9. Liver phantom for quality control and training in nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Lima Ferreira, Fernanda Carla [Departamento de Fisica, Universidade Federal de Sergipe, Sao Cristovao, SE, 49100 000 (Brazil); Nascimento Souza, Divanizia do, E-mail: divanizi@ufs.br [Departamento de Fisica, Universidade Federal de Sergipe, Sao Cristovao, SE, 49100 000 (Brazil)

    2011-10-01

    In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256x256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

  10. Liver phantom for quality control and training in nuclear medicine

    Science.gov (United States)

    Lima Ferreira, Fernanda Carla; Souza, Divanizia do Nascimento

    2011-10-01

    In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256×256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

  11. Contrast detail phantom for SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Cabrejas, M.L. de; Arashiro, J G; Giannone, C. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Camuyrano, M; Nohara, G [Universidad de Buenos Aires, Buenos Aires (Argentina). Facultad Ciencias Exactas

    1996-06-01

    A new low variable contrast phantom for single photon emission computed tomography (SPECT) was constructed, tested and compared with other existing phantoms. It contains simulated cylindrical lesions of four different diameters (D{sub i}), embedded in a cylindrical scattering medium and a uniform section to evaluate tomographic uniformity. The concentration of tracer in the simulated lesions and the scattering medium (background) can be varied to simulate hot and cold lesions. Different applications of the phantom were tested, including determination of the minimum object contrast (OCm) necessary to detect lesions as a function of lesion size, lesion type (hot or cold) and acquisition and processing protocols by visual inspection. This parameter allows categorization of instruments comparing an `image quality index` (IQI). Preliminary comparison with the Britten contrast processing method showed that the detectable OCm was of the same order of magnitude, but the presented device seems more suitable for training and intercomparison purposes. The constructed phantom, of simple design, has proved to be useful for acquisition and processing condition evaluation, OCm estimation and external quality control. (author). 11 refs, 4 figs.

  12. SU-E-P-59: A Graphical Interface for XCAT Phantom Configuration, Generation and Processing

    International Nuclear Information System (INIS)

    Myronakis, M; Cai, W; Dhou, S; Cifter, F; Lewis, J; Hurwitz, M

    2015-01-01

    Purpose: To design a comprehensive open-source, publicly available, graphical user interface (GUI) to facilitate the configuration, generation, processing and use of the 4D Extended Cardiac-Torso (XCAT) phantom. Methods: The XCAT phantom includes over 9000 anatomical objects as well as respiratory, cardiac and tumor motion. It is widely used for research studies in medical imaging and radiotherapy. The phantom generation process involves the configuration of a text script to parameterize the geometry, motion, and composition of the whole body and objects within it, and to generate simulated PET or CT images. To avoid the need for manual editing or script writing, our MATLAB-based GUI uses slider controls, drop-down lists, buttons and graphical text input to parameterize and process the phantom. Results: Our GUI can be used to: a) generate parameter files; b) generate the voxelized phantom; c) combine the phantom with a lesion; d) display the phantom; e) produce average and maximum intensity images from the phantom output files; f) incorporate irregular patient breathing patterns; and f) generate DICOM files containing phantom images. The GUI provides local help information using tool-tip strings on the currently selected phantom, minimizing the need for external documentation. The DICOM generation feature is intended to simplify the process of importing the phantom images into radiotherapy treatment planning systems or other clinical software. Conclusion: The GUI simplifies and automates the use of the XCAT phantom for imaging-based research projects in medical imaging or radiotherapy. This has the potential to accelerate research conducted with the XCAT phantom, or to ease the learning curve for new users. This tool does not include the XCAT phantom software itself. We would like to acknowledge funding from MRA, Varian Medical Systems Inc

  13. SU-E-P-59: A Graphical Interface for XCAT Phantom Configuration, Generation and Processing

    Energy Technology Data Exchange (ETDEWEB)

    Myronakis, M; Cai, W; Dhou, S; Cifter, F; Lewis, J [Brigham and Women’s Hospital, Boston, MA (United States); Hurwitz, M [Newton, MA (United States)

    2015-06-15

    Purpose: To design a comprehensive open-source, publicly available, graphical user interface (GUI) to facilitate the configuration, generation, processing and use of the 4D Extended Cardiac-Torso (XCAT) phantom. Methods: The XCAT phantom includes over 9000 anatomical objects as well as respiratory, cardiac and tumor motion. It is widely used for research studies in medical imaging and radiotherapy. The phantom generation process involves the configuration of a text script to parameterize the geometry, motion, and composition of the whole body and objects within it, and to generate simulated PET or CT images. To avoid the need for manual editing or script writing, our MATLAB-based GUI uses slider controls, drop-down lists, buttons and graphical text input to parameterize and process the phantom. Results: Our GUI can be used to: a) generate parameter files; b) generate the voxelized phantom; c) combine the phantom with a lesion; d) display the phantom; e) produce average and maximum intensity images from the phantom output files; f) incorporate irregular patient breathing patterns; and f) generate DICOM files containing phantom images. The GUI provides local help information using tool-tip strings on the currently selected phantom, minimizing the need for external documentation. The DICOM generation feature is intended to simplify the process of importing the phantom images into radiotherapy treatment planning systems or other clinical software. Conclusion: The GUI simplifies and automates the use of the XCAT phantom for imaging-based research projects in medical imaging or radiotherapy. This has the potential to accelerate research conducted with the XCAT phantom, or to ease the learning curve for new users. This tool does not include the XCAT phantom software itself. We would like to acknowledge funding from MRA, Varian Medical Systems Inc.

  14. Development of polygonal surface version of ICRP reference phantoms: Preliminary study for posture change

    International Nuclear Information System (INIS)

    Nguyen, Tat Thang; Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong

    2013-01-01

    Even though International Commission on Radiological Protection (ICRP) officially adopted a set of adult male and female voxel phantoms as the ICRP reference phantoms, there are several critical limitations due to the nature of voxel geometry and their low voxel resolutions. In order to overcome these limitations of the ICRP phantoms, we are currently developing polygonal surface version of ICRP reference phantoms by directly converting the ICRP voxel phantoms to polygonal surface geometries. Among the many advantages of the ICRP polygonal surface phantom, especially, it is flexible and deformable. In principle, it is, therefore, possible to make the posture-changed ICRP phantoms which can provide more accurate dose values for exposure situations strongly relevant to worker's postures. As a preliminary study for developing the posture-changed ICRP phantoms, in this work we changed the posture of the preliminary version of ICRP male polygon-surface phantom constructed in the previous study. Organ doses were then compared between original and posture-changed phantoms. In the present study, we successfully changed a posture of the preliminary version of ICRP male polygon-surface phantom to the walking posture. From this results, it was explicitly shown that the polygon-surface version of the ICRP phantoms can be sufficiently modified to be various postures with the posture-changing method used in this study. In addition, it was demonstrated that phantom's posture must be considered in certain exposure situations, which can differ dose values from the conventional standing-posture phantom

  15. Prevalent hallucinations during medical internships: phantom vibration and ringing syndromes.

    Directory of Open Access Journals (Sweden)

    Yu-Hsuan Lin

    Full Text Available BACKGROUND: Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. METHODS: A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. RESULTS: The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. CONCLUSION: This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships.

  16. Side-by-Side Testing of Water Heating Systems: Results from the 2013-2014 Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Colon, Carlos [Florida Solar Energy Center, Cocoa, FL (United States). Bulding America Partnership for Improved Residential Construction

    2017-07-12

    The Florida Solar Energy Center (FSEC) has completed a fourth year-long evaluation on residential hot water heating systems in a laboratory environment (east central Florida, hot-humid climate). This report contains a summary of research activities regarding the evaluation of two residential electric heat pump water heaters (HPWHs), a solar thermal system utilizing a polymer glazed absorber and a high efficiency natural gas system.

  17. SU-F-I-14: 3D Breast Digital Phantom for XACT Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tang, S; Laaroussi, R; Chen, J; Samant, P; Xiang, L [University of Oklahoma, Norman, OK (United States); Chen, Y; Ahmad, S [University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States); Yang, K [Massachusetts General Hospital, Boston, MA (United States)

    2016-06-15

    Purpose: The X-ray induced acoustic computed tomography (XACT) is a new imaging modality which combines X-ray contrast and high ultrasonic resolution in a single modality. Using XACT in breast imaging, a 3D breast volume can be imaged by only one pulsed X-ray radiation, which could dramatically reduce the imaging dose for patients undergoing breast cancer screening and diagnosis. A 3D digital phantom that contains both X-ray properties and acoustic properties of different tissue types is indeed needed for developing and optimizing the XACT system. The purpose of this study is to offer a realistic breast digital phantom as a valuable tool for improving breast XACT imaging techniques and potentially leading to better diagnostic outcomes. Methods: A series of breast CT images along the coronal plane from a patient who has breast calcifications are used as the source images. A HU value based segmentation algorithm is employed to identify breast tissues in five categories, namely the skin tissue, fat tissue, glandular tissue, chest bone and calcifications. For each pixel, the dose related parameters, such as material components and density, and acoustic related parameters, such as frequency-dependent acoustic attenuation coefficient and bandwidth, are assigned based on tissue types. Meanwhile, other parameters which are used in sound propagation, including the sound speed, thermal expansion coefficient, and heat capacity are also assigned to each tissue. Results: A series of 2D tissue type image is acquired first and the 3D digital breast phantom is obtained by using commercial 3D reconstruction software. When giving specific settings including dose depositions and ultrasound center frequency, the X-ray induced initial pressure rise can be calculated accordingly. Conclusion: The proposed 3D breast digital phantom represents a realistic breast anatomic structure and provides a valuable tool for developing and evaluating the system performance for XACT.

  18. Acceleration/heating of plasma on auroral field lines: preliminary results from the Viking satellite

    International Nuclear Information System (INIS)

    Lundin, R.

    1988-01-01

    In this report, a review of the first results obtained from the particle experiment on board the Viking spacecraft will be given. During the first part of the Viking mission, the orbit was suitable for high-altitude measurements (up to ∼ 13500 km) in the dayside oval and the cusp/cleft region. Thus, some emphasis will be put on processes occurring in the dayside auroral region. On the basis of more than 100 Viking traversals of the cusp and cleft it is suggested that these regions can be identified by some regular characteristics in the particle data. The cusp has a continuous presence of solar wind plasma, affected mainly by convection and containing modest plasma energization. Conversely, the cleft is characterized by extensive plasma energization, and strong field aligned current sheets. Temporal injections of solar wind plasma are frequently observed in the cleft. A distinguishing characteristic of the Viking charged particle experiment is the energy and angular resolution. Thus, the fine-structure of narrow particle beams and conical distributions of both electrons and ions can be determined. This enables very detailed studies of the plasma acceleration processes along auroral field lines. Some examples of accelerated plasma populations and their related energy and angular distribution will be presented. The observations are compared with existing theories of auroral plasma heating and acceleration processes

  19. Conductive heat flow at the TAG Active Hydrothermal Mound: Results from 1993-1995 submersible surveys

    Science.gov (United States)

    Becker, K.; Von Herzen, R.; Kirklin, J.; Evans, R.; Kadko, D.; Kinoshita, M.; Matsubayashi, O.; Mills, R.; Schultz, A.; Rona, P.

    We report 70 measurements of conductive heat flow at the 50-m-high, 200-m-diameter TAG active hydrothermal mound, made during submersible surveys with Alvin in 1993 and 1995 and Shinkai 6500 in 1994. The stations were all measured with 5-thermistor, 0.6- or 1-m-long Alvin heat flow probes, which are capable of determining both gradient and thermal conductivity, and were transponder-navigated to an estimated accuracy of ±5-10 m relative to the 10-m-diameter central complex of black smokers. Within 20 m of this complex, conductive heat flow values are extremely variable (0.1- > 100 W/m²), which can only be due to local spatial and possible temporal variability in the immediate vicinity of the vigorous discharge sites. A similar local variability is suggested in the “Kremlin” area of white smokers to the southeast of the black smoker complex. On the south and southeast side of the mound, there is very high heat flow (3.7- > 25 W/m²) on the sedimented terraces that slope down from the Kremlin area. Heat flow is also high (0.3-3 W/m²) in the pelagic carbonate sediments on the surrounding seafloor within a few tens of meters of the southwest, northwest, and northeast sides of the mound. On the west side of the sulfide rubble plateau that surrounds the central black smoker peak, there is a coherent belt of very low heat flow (smokers, suggestive of local, shallow recharge of bottom water. The three submersible surveys spanned nearly two years, but showed no indication of any temporal variability in conductive heat flow over this time scale, whether natural or induced by ODP drilling in 1994.

  20. Magnetoencephalography Phantom Comparison and Validation: Hospital Universiti Sains Malaysia (HUSM) Requisite.

    Science.gov (United States)

    Omar, Hazim; Ahmad, Alwani Liyan; Hayashi, Noburo; Idris, Zamzuri; Abdullah, Jafri Malin

    2015-12-01

    Magnetoencephalography (MEG) has been extensively used to measure small-scale neuronal brain activity. Although it is widely acknowledged as a sensitive tool for deciphering brain activity and source localisation, the accuracy of the MEG system must be critically evaluated. Typically, on-site calibration with the provided phantom (Local phantom) is used. However, this method is still questionable due to the uncertainty that may originate from the phantom itself. Ideally, the validation of MEG data measurements would require cross-site comparability. A simple method of phantom testing was used twice in addition to a measurement taken with a calibrated reference phantom (RefPhantom) obtained from Elekta Oy of Helsinki, Finland. The comparisons of two main aspects were made in terms of the dipole moment (Qpp) and the difference in the dipole distance from the origin (d) after the tests of statistically equal means and variance were confirmed. The result of Qpp measurements for the LocalPhantom and RefPhantom were 978 (SD24) nAm and 988 (SD32) nAm, respectively, and were still optimally within the accepted range of 900 to 1100 nAm. Moreover, the shifted d results for the LocalPhantom and RefPhantom were 1.84 mm (SD 0.53) and 2.14 mm (SD 0.78), respectively, and these values were below the maximum acceptance range of within 5.0 mm of the nominal dipole location. The Local phantom seems to outperform the reference phantom as indicated by the small standard error of the former (SE 0.094) compared with the latter (SE 0.138). The result indicated that HUSM MEG system was in excellent working condition in terms of the dipole magnitude and localisation measurements as these values passed the acceptance limits criteria of the phantom test.

  1. 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

  2. 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.

  3. 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

  4. Efficiency of heat pump plants. Results of field tests; Effizienz von Waermepumpenanlagen. Ergebnisse aus Felduntersuchungen

    Energy Technology Data Exchange (ETDEWEB)

    Miara, Marek; Guenther, Danny [Fraunhofer-Institut fuer Solare Energiesysteme ISE (Germany)

    2011-07-01

    In Germany, households account for about 30 percent of the total end use energy consumption. In fact, if heating and water heating are taken into account, the total amounts to more than 80 percent. This shows the necessity of making heating more energy-efficient and ecological. Heat pumps are an interesting solution. The contribution investigates their efficiency in real conditions, both in new and older buildings, and also goes into the possibility of optimization during installation, control and operation. The contribution is based on the long-term heat pump monitoring projects of Fraunhofer Institut fuer Solare Energiesysteme ISE of Freiburg. [German] In den deutschen Haushalten werden rund 30 % der Endenergie verbraucht. Obwohl der Bedarf fuer die Heizung oftmals unterschaetzt wird, entfallen in den Haushalten auf die Bereiche Raumwaerme und Warmwasser tatsaechlich mehr als 80 % des Energieverbrauches. Angesichts des fortschreitenden Klimawandels sowie der Ressourcenknappheit ist es dringend notwendig, die notwendige Heizenergie moeglichst effizient und oekologisch bereitzustellen. Die Waermepumpentechnologie ist in der Lage diesen Anforderungen gerecht zu werden. Wie effizient allerdings sind die Waermepumpenanlagen unter realen Bedingungen sowohl bei Neubauten als auch bei Bestandsgebaeuden? Oder: welche Optimierungsmoeglichkeiten bestehen bei Installation, Regelung sowie Betrieb von Waermepumpenanlagen? Um diese Fragen beantworten zu koennen, fuehrt das Fraunhofer Institut fuer Solare Energiesysteme ISE aus Freiburg seit mehreren Jahren umfangreiche Monitoringprojekte durch in denen Waermepumpenanlagen im Mittelpunkt der Untersuchung stehen.

  5. Standardization of calibration method of whole-body counter. 1. Calibration by using anthropometric phantoms

    International Nuclear Information System (INIS)

    Ishikawa, Tetsuo; Matsumoto, Masaki; Uchiyama, Masafumi; Kobayashi, Sadayoshi; Mizushita, Seiichi.

    1995-01-01

    To standardize the calibration methods of whole-body counters, three anthropometric phantoms were manufactured based on dozens of Japanese average value of body size data. Using these phantoms, the calibrations of some whole-body counters were carried out and the comparison of counting efficiency between anthropometric phantoms and block phantoms, which used to be used for the calibration of whole-body counters generally, was implemented. Five whole-body counters, one scanning system, two stationary systems and two chair systems, were used for this study. The following results were derived: As an example, in NIRS scanning system, the counting efficiency of anthropometric phantom of 162cm height was 12.7% greater than that of block phantom of the same height. This means 137 Cs body burdens in adult men used to be estimated with the excess of about 10%. Body burdens tended to be estimated excessively in adult because the difference of counting efficiency between anthropometric phantom and block phantom increases with increase of height. To standardize body burden data measured with various whole-body counters, the calibration of each whole-body counter should be conducted using anthropometric phantoms and phantoms which used to be used for the calibration of that whole-body counter. (author)

  6. Agency over Phantom Limb Enhanced by Short-Term Mirror Therapy.

    Science.gov (United States)

    Imaizumi, Shu; Asai, Tomohisa; Koyama, Shinichi

    2017-01-01

    Most amputees experience phantom limb, whereby they feel that the amputated limb is still present. In some cases, these experiences include pain that can be alleviated by "mirror therapy." Mirror therapy consists of superimposing a mirrored image of the moving intact limb onto the phantom limb. This therapy provides a closed loop between the motor command to the amputated limb and its predicted visual feedback. This loop is also involved in the sense of agency, a feeling of controlling one's own body. However, it is unclear how mirror therapy is related to the sense of agency over a phantom limb. Using mirror therapy, we investigated phantom limb pain and the senses of agency and ownership (i.e., a feeling of having one's own body) of the phantom limb. Nine upper-limb amputees, five of whom reported recent phantom limb pain, underwent a single 15-min trial of mirror therapy. Before and after the trial, the participants completed a questionnaire regarding agency, ownership, and pain related to their phantom limb. They reported that the sense of agency over the phantom limb increased following the mirror therapy trial, while the ownership slightly increased but not as much as did the agency. The reported pain did not change; that is, it was comparably mild before and after the trial. These results suggest that short-term mirror therapy can, at least transiently, selectively enhance the sense of agency over a phantom limb, but may not alleviate phantom limb pain.

  7. Structural integrity assessment of intermediate heat exchanger in the HTTR. Based on results of rise-to-power test

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Takeshi; Tachibana, Yukio; Nakagawa, Shigeaki [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    2002-12-01

    A helium/helium intermediate heat exchanger (IHX) in the high temperature engineering test reactor (HTTR) is an essential component for demonstration of future nuclear process heat utilization of high temperature gas-cooled reactor (HTGR). The IHX with a heat capacity of 10 MW has 96 helically-coiled heat transfer tubes. Structural design for the IHX had been conducted through elastic-creep analysis of superalloy Hastelloy XR components such as heat transfer tubes and center pipe. In the HTTR rise-to-power test, it was clarified that temperature of the coolant in the IHX at the reactor scrams changes more rapidly than expected in the design. Effects of the IHX coolant temperature change, at anticipated reactor scram from the full power of 30 MW at high temperature test operation, on structural integrity of the heat transfer tubes and the lower reducer of the center pipe were investigated analytically based on the coolant temperature data obtained from the rise-to-power test. As results of the assessment, it was confirmed that cumulative principal creep strain, cumulative creep and fatigue damage factor of the IHX components during 10{sup 5} h of the HTTR lifetime should be below the allowable limits, which are established in the high-temperature structural design code for the HTGR Class 1 components. (author)

  8. Results from a CFD reference study into the modelling of heat and smoke transport by different CFD-practitioners

    NARCIS (Netherlands)

    Loomans, M.G.L.C.; Lemaire, A.D.; Plas, van der M.

    2009-01-01

    The paper describes results from a reference study that focuses on the application of the Computational Fluid Dynamics (CFD-) technique for heat and smoke transport in practice. Goal of the study is to obtain insight into the amount and causes of the spread of CFD-results when applied by different

  9. Pulsating Heat pipe Only for Space (PHOS): results of the REXUS 18 sounding rocket campaign

    International Nuclear Information System (INIS)

    Creatini, F; Guidi, G M; Belfi, F; Cicero, G; Fioriti, D; Di Prizio, D; Piacquadio, S; Becatti, G; Orlandini, G; Frigerio, A; Fontanesi, S; Nannipieri, P; Rognini, M; Morganti, N; Filippeschi, S; Di Marco, P; Fanucci, L; Baronti, F; Mameli, M; Manzoni, M

    2015-01-01

    Two Closed Loop Pulsating Heat Pipes (CLPHPs) are tested on board REXUS 18 sounding rocket in order to obtain data over a relatively long microgravity period (approximately 90 s). The CLPHPs are partially filled with FC-72 and have, respectively, an inner tube diameter larger (3 mm) and slightly smaller (1.6 mm) than the critical diameter evaluated in static Earth gravity conditions. On ground, the small diameter CLPHP effectively works as a Pulsating Heat Pipe (PHP): the characteristic slug and plug flow pattern forms inside the tube and the heat exchange is triggered by thermally driven self-sustained oscillations of the working fluid. On the other hand, the large diameter CLPHP works as a two- phase thermosyphon in vertical position and doesn't work in horizontal position: in this particular condition, the working fluid stratifies within the device as the surface tension force is no longer able to balance buoyancy. Then, the idea to test the CLPHPs in reduced gravity conditions: as the gravity reduces the buoyancy forces becomes less intense and it is possible to recreate the typical PHP flow pattern also for larger inner tube diameters. This allows to increase the heat transfer rate and, consequently, to decrease the overall thermal resistance. Even though it was not possible to experience low gravity conditions due to a failure in the yoyo de-spin system, the thermal response to the peculiar acceleration field (hyper-gravity) experienced on board are thoroughly described. (paper)

  10. SRB thermal protection systems materials test results in an arc-heated nitrogen environment

    Science.gov (United States)

    Wojciechowski, C. J.

    1979-01-01

    The external surface of the Solid Rocket Booster (SRB) will experience imposed thermal and shear environments due to aerodynamic heating and radiation heating during launch, staging and reentry. This report is concerned with the performance of the various TPS materials during the staging maneuver. During staging, the wash from the Space Shuttle Main Engine (SSME) exhust plumes impose severe, short duration, thermal environments on the SRB. Five different SRB TPS materials were tested in the 1 MW Arc Plasma Generator (APG) facility. The maximum simulated heating rate obtained in the APG facility was 248 Btu/sq ft./sec, however, the test duration was such that the total heat was more than simulated. Similarly, some local high shear stress levels of 0.04 psia were not simulated. Most of the SSME plume impingement area on the SRB experiences shear stress levels of 0.02 psia and lower. The shear stress levels on the test specimens were between 0.021 and 0.008 psia. The SSME plume stagnation conditions were also simulated.

  11. 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)

  12. 3D Printing Openable Imaging Phantom Design

    International Nuclear Information System (INIS)

    Kim, Myoung Keun; Won, Jun Hyeok; Lee, Seung Wook

    2017-01-01

    The purpose of this study is to design an openable phantom that can replace the internal measurement bar used for contrast comparison in order to increase the efficiency of manufacturing imaging phantom used in the medical industry and to improve convenience using 3D printer. Phantom concept design, 3D printing, and Image reconstruction were defined as the scope of the thesis. Also, we study metal artifact reduction with openable phantom. We have designed a Openable phantom using 3D printing, and have investigated metal artifact reduction after inserting a metallic material inside the phantom. The openable phantom can be adjusted at any time to suit the user's experiment and can be easily replaced and useful.

  13. Monte Carlo dose calculations for phantoms with hip prostheses

    International Nuclear Information System (INIS)

    Bazalova, M; Verhaegen, F; Coolens, C; Childs, P; Cury, F; Beaulieu, L

    2008-01-01

    Computed tomography (CT) images of patients with hip prostheses are severely degraded by metal streaking artefacts. The low image quality makes organ contouring more difficult and can result in large dose calculation errors when Monte Carlo (MC) techniques are used. In this work, the extent of streaking artefacts produced by three common hip prosthesis materials (Ti-alloy, stainless steel, and Co-Cr-Mo alloy) was studied. The prostheses were tested in a hypothetical prostate treatment with five 18 MV photon beams. The dose distributions for unilateral and bilateral prosthesis phantoms were calculated with the EGSnrc/DOSXYZnrc MC code. This was done in three phantom geometries: in the exact geometry, in the original CT geometry, and in an artefact-corrected geometry. The artefact-corrected geometry was created using a modified filtered back-projection correction technique. It was found that unilateral prosthesis phantoms do not show large dose calculation errors, as long as the beams miss the artefact-affected volume. This is possible to achieve in the case of unilateral prosthesis phantoms (except for the Co-Cr-Mo prosthesis which gives a 3% error) but not in the case of bilateral prosthesis phantoms. The largest dose discrepancies were obtained for the bilateral Co-Cr-Mo hip prosthesis phantom, up to 11% in some voxels within the prostate. The artefact correction algorithm worked well for all phantoms and resulted in dose calculation errors below 2%. In conclusion, a MC treatment plan should include an artefact correction algorithm when treating patients with hip prostheses

  14. 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

  15. 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.

  16. Technical Note: Characterization of custom 3D printed multimodality imaging phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Bieniosek, Matthew F. [Department of Electrical Engineering, Stanford University, 350 Serra Mall, Stanford, California 94305 (United States); Lee, Brian J. [Department of Mechanical Engineering, Stanford University, 440 Escondido Mall, Stanford, California 94305 (United States); Levin, Craig S., E-mail: cslevin@stanford.edu [Departments of Radiology, Physics, Bioengineering and Electrical Engineering, Stanford University, 300 Pasteur Dr., Stanford, California 94305-5128 (United States)

    2015-10-15

    Purpose: Imaging phantoms are important tools for researchers and technicians, but they can be costly and difficult to customize. Three dimensional (3D) printing is a widely available rapid prototyping technique that enables the fabrication of objects with 3D computer generated geometries. It is ideal for quickly producing customized, low cost, multimodal, reusable imaging phantoms. This work validates the use of 3D printed phantoms by comparing CT and PET scans of a 3D printed phantom and a commercial “Micro Deluxe” phantom. This report also presents results from a customized 3D printed PET/MRI phantom, and a customized high resolution imaging phantom with sub-mm features. Methods: CT and PET scans of a 3D printed phantom and a commercial Micro Deluxe (Data Spectrum Corporation, USA) phantom with 1.2, 1.6, 2.4, 3.2, 4.0, and 4.8 mm diameter hot rods were acquired. The measured PET and CT rod sizes, activities, and attenuation coefficients were compared. A PET/MRI scan of a custom 3D printed phantom with hot and cold rods was performed, with photon attenuation and normalization measurements performed with a separate 3D printed normalization phantom. X-ray transmission scans of a customized two level high resolution 3D printed phantom with sub-mm features were also performed. Results: Results show very good agreement between commercial and 3D printed micro deluxe phantoms with less than 3% difference in CT measured rod diameter, less than 5% difference in PET measured rod diameter, and a maximum of 6.2% difference in average rod activity from a 10 min, 333 kBq/ml (9 μCi/ml) Siemens Inveon (Siemens Healthcare, Germany) PET scan. In all cases, these differences were within the measurement uncertainties of our setups. PET/MRI scans successfully identified 3D printed hot and cold rods on PET and MRI modalities. X-ray projection images of a 3D printed high resolution phantom identified features as small as 350 μm wide. Conclusions: This work shows that 3D printed

  17. Technical Note: Characterization of custom 3D printed multimodality imaging phantoms

    International Nuclear Information System (INIS)

    Bieniosek, Matthew F.; Lee, Brian J.; Levin, Craig S.

    2015-01-01

    Purpose: Imaging phantoms are important tools for researchers and technicians, but they can be costly and difficult to customize. Three dimensional (3D) printing is a widely available rapid prototyping technique that enables the fabrication of objects with 3D computer generated geometries. It is ideal for quickly producing customized, low cost, multimodal, reusable imaging phantoms. This work validates the use of 3D printed phantoms by comparing CT and PET scans of a 3D printed phantom and a commercial “Micro Deluxe” phantom. This report also presents results from a customized 3D printed PET/MRI phantom, and a customized high resolution imaging phantom with sub-mm features. Methods: CT and PET scans of a 3D printed phantom and a commercial Micro Deluxe (Data Spectrum Corporation, USA) phantom with 1.2, 1.6, 2.4, 3.2, 4.0, and 4.8 mm diameter hot rods were acquired. The measured PET and CT rod sizes, activities, and attenuation coefficients were compared. A PET/MRI scan of a custom 3D printed phantom with hot and cold rods was performed, with photon attenuation and normalization measurements performed with a separate 3D printed normalization phantom. X-ray transmission scans of a customized two level high resolution 3D printed phantom with sub-mm features were also performed. Results: Results show very good agreement between commercial and 3D printed micro deluxe phantoms with less than 3% difference in CT measured rod diameter, less than 5% difference in PET measured rod diameter, and a maximum of 6.2% difference in average rod activity from a 10 min, 333 kBq/ml (9 μCi/ml) Siemens Inveon (Siemens Healthcare, Germany) PET scan. In all cases, these differences were within the measurement uncertainties of our setups. PET/MRI scans successfully identified 3D printed hot and cold rods on PET and MRI modalities. X-ray projection images of a 3D printed high resolution phantom identified features as small as 350 μm wide. Conclusions: This work shows that 3D printed

  18. Technical Note: Characterization of custom 3D printed multimodality imaging phantoms.

    Science.gov (United States)

    Bieniosek, Matthew F; Lee, Brian J; Levin, Craig S

    2015-10-01

    Imaging phantoms are important tools for researchers and technicians, but they can be costly and difficult to customize. Three dimensional (3D) printing is a widely available rapid prototyping technique that enables the fabrication of objects with 3D computer generated geometries. It is ideal for quickly producing customized, low cost, multimodal, reusable imaging phantoms. This work validates the use of 3D printed phantoms by comparing CT and PET scans of a 3D printed phantom and a commercial "Micro Deluxe" phantom. This report also presents results from a customized 3D printed PET/MRI phantom, and a customized high resolution imaging phantom with sub-mm features. CT and PET scans of a 3D printed phantom and a commercial Micro Deluxe (Data Spectrum Corporation, USA) phantom with 1.2, 1.6, 2.4, 3.2, 4.0, and 4.8 mm diameter hot rods were acquired. The measured PET and CT rod sizes, activities, and attenuation coefficients were compared. A PET/MRI scan of a custom 3D printed phantom with hot and cold rods was performed, with photon attenuation and normalization measurements performed with a separate 3D printed normalization phantom. X-ray transmission scans of a customized two level high resolution 3D printed phantom with sub-mm features were also performed. Results show very good agreement between commercial and 3D printed micro deluxe phantoms with less than 3% difference in CT measured rod diameter, less than 5% difference in PET measured rod diameter, and a maximum of 6.2% difference in average rod activity from a 10 min, 333 kBq/ml (9 μCi/ml) Siemens Inveon (Siemens Healthcare, Germany) PET scan. In all cases, these differences were within the measurement uncertainties of our setups. PET/MRI scans successfully identified 3D printed hot and cold rods on PET and MRI modalities. X-ray projection images of a 3D printed high resolution phantom identified features as small as 350 μm wide. This work shows that 3D printed phantoms can be functionally equivalent to

  19. Fuzzy classification of phantom parent groups in an animal model

    Directory of Open Access Journals (Sweden)

    Fikse Freddy

    2009-09-01

    Full Text Available Abstract Background Genetic evaluation models often include genetic groups to account for unequal genetic level of animals with unknown parentage. The definition of phantom parent groups usually includes a time component (e.g. years. Combining several time periods to ensure sufficiently large groups may create problems since all phantom parents in a group are considered contemporaries. Methods To avoid the downside of such distinct classification, a fuzzy logic approach is suggested. A phantom parent can be assigned to several genetic groups, with proportions between zero and one that sum to one. Rules were presented for assigning coefficients to the inverse of the relationship matrix for fuzzy-classified genetic groups. This approach was illustrated with simulated data from ten generations of mass selection. Observations and pedigree records were randomly deleted. Phantom parent groups were defined on the basis of gender and generation number. In one scenario, uncertainty about generation of birth was simulated for some animals with unknown parents. In the distinct classification, one of the two possible generations of birth was randomly chosen to assign phantom parents to genetic groups for animals with simulated uncertainty, whereas the phantom parents were assigned to both possible genetic groups in the fuzzy classification. Results The empirical prediction error variance (PEV was somewhat lower for fuzzy-classified genetic groups. The ranking of animals with unknown parents was more correct and less variable across replicates in comparison with distinct genetic groups. In another scenario, each phantom parent was assigned to three groups, one pertaining to its gender, and two pertaining to the first and last generation, with proportion depending on the (true generation of birth. Due to the lower number of groups, the empirical PEV of breeding values was smaller when genetic groups were fuzzy-classified. Conclusion Fuzzy

  20. Some results from a Mellin transform expansion for the heat Kernel

    International Nuclear Information System (INIS)

    Malbouisson, A.P.C.; Simao, F.R.A.; Camargo Filho, A.F. de.

    1988-01-01

    The coefficients of a new Heat Kernel expansion, in the case of a differential operator containing a gauge field. The meromorphic structure of the generalized zeta-function obtained by that expansion is compared with the one obtained in a proceeding paper. The expansion is applied to anomalies, obtaining a general formula for arbitrary dimension D. The special cases D=2 and D=3 are investigated. (author) [pt

  1. Airflow Obstruction and Use of Solid Fuels for Cooking or Heating: BOLD Results.

    Science.gov (United States)

    Amaral, André F S; Patel, Jaymini; Kato, Bernet S; Obaseki, Daniel O; Lawin, Hervé; Tan, Wan C; Juvekar, Sanjay K; Harrabi, Imed; Studnicka, Michael; Wouters, Emiel F M; Loh, Li-Cher; Bateman, Eric D; Mortimer, Kevin; Buist, A Sonia; Burney, Peter G J

    2017-09-12

    Evidence supporting the association of COPD or airflow obstruction with use of solid fuels is conflicting and inconsistent. To assess the association of airflow obstruction with self-reported use of solid fuels for cooking or heating. We analysed 18,554 adults from the BOLD study, who had provided acceptable post-bronchodilator spirometry measurements and information on use of solid fuels. The association of airflow obstruction with use of solid fuels for cooking or heating was assessed by sex, within each site, using regression analysis. Estimates were stratified by national income and meta-analysed. We carried out similar analyses for spirometric restriction, chronic cough and chronic phlegm. We found no association between airflow obstruction and use of solid fuels for cooking or heating (ORmen=1.20, 95%CI 0.94-1.53; ORwomen=0.88, 95%CI 0.67-1.15). This was true for low/middle and high income sites. Among never smokers there was also no evidence of an association of airflow obstruction with use of solid fuels (ORmen=1.00, 95%CI 0.57-1.76; ORwomen=1.00, 95%CI 0.76-1.32). Overall, we found no association of spirometric restriction, chronic cough or chronic phlegm with the use of solid fuels. However, we found that chronic phlegm was more likely to be reported among female never smokers and those who had been exposed for ≥20 years. Airflow obstruction assessed from post-bronchodilator spirometry was not associated with use of solid fuels for cooking or heating.

  2. 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.

  3. Quantification of breast density using dual-energy mammography with liquid phantom calibration

    International Nuclear Information System (INIS)

    Lam, Alfonso R; Ding, Huanjun; Molloi, Sabee

    2014-01-01

    Breast density is a widely recognized potential risk factor for breast cancer. However, accurate quantification of breast density is a challenging task in mammography. The current use of plastic breast-equivalent phantoms for calibration provides limited accuracy in dual-energy mammography due to the chemical composition of the phantom. We implemented a breast-equivalent liquid phantom for dual-energy calibration in order to improve the accuracy of breast density measurement. To design these phantoms, three liquid compounds were chosen: water, isopropyl alcohol, and glycerol. Chemical compositions of glandular and adipose tissues, obtained from NIST database, were used as reference materials. Dual-energy signal of the liquid phantom at different breast densities (0% to 100%) and thicknesses (1 to 8 cm) were simulated. Glandular and adipose tissue thicknesses were estimated from a higher order polynomial of the signals. Our results indicated that the linear attenuation coefficients of the breast-equivalent liquid phantoms match those of the target material. Comparison between measured and known breast density data shows a linear correlation with a slope close to 1 and a non-zero intercept of 7%, while plastic phantoms showed a slope of 0.6 and a non-zero intercept of 8%. Breast density results derived from the liquid calibration phantoms showed higher accuracy than those derived from the plastic phantoms for different breast thicknesses and various tube voltages. We performed experimental phantom studies using liquid phantoms and then compared the computed breast density with those obtained using a bovine tissue model. The experimental data and the known values were in good correlation with a slope close to 1 (∼1.1). In conclusion, our results indicate that liquid phantoms are a reliable alternative for calibration in dual-energy mammography and better reproduce the chemical properties of the target material. (paper)

  4. Removal of contaminated concrete surfaces by microwave heating: Phase 1 results

    International Nuclear Information System (INIS)

    White, T.L.; Grubb, R.G.; Pugh, L.P.; Foster, D. Jr.; Box, W.D.

    1992-01-01

    Oak Ridge National Laboratory (ORNL) is developing a microwave heating process to remove radiologically contaminated surface layers from concrete. The microwave energy is directed at the concrete surface and heats the concrete and free water present in the concrete matrix. Continued heating produces steam-pressure-induced mechanical stresses that cause the concrete surface to burst. The concrete particles from this steam explosion are small enough to be removed by a vacuum system, yet less than 1% of the debris is small enough to pose an airborne contamination hazard. The first phase of this program has demonstrated reliable removal of noncontaminated concrete surfaces at frequencies of 2.45 GHz and 10.6 GHz. Continuous concrete removal rates of 1.07 cm 3 /s with 5.2 kW of 2.45.-GHz power and 2.11 cm 3 /s with 3.6 kW of 10.6-GHz power have been demonstrated. Figures-of-merit for microwave removal of concrete have been calculated to be 0.21 cm 3 /s/kW at 2.45 GHz and 0.59 cm 3 /s/kW at 10.6 GHz. The amount of concrete removed in a single pass can be controlled by choosing the frequency and power of the microwave system

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

    International Nuclear Information System (INIS)

    Lee, Choonsik; Lodwick, Daniel; Hasenauer, Deanna; Williams, Jonathan L; Lee, Choonik; Bolch, Wesley E

    2007-01-01

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

  6. Effect of phantom voxelization in CT simulations

    International Nuclear Information System (INIS)

    Goertzen, Andrew L.; Beekman, Freek J.; Cherry, Simon R.

    2002-01-01

    In computer simulations of x-ray CT systems one can either use continuous geometrical descriptions for phantoms or a voxelized representation. The voxelized approach allows arbitrary phantoms to be defined without being confined to geometrical shapes. The disadvantage of the voxelized approach is that inherent errors are introduced due to the phantom voxelization. To study effects of phantom discretization, analytical CT simulations were run for a fan-beam geometry with phantom voxel sizes ranging from 0.0625 to 2 times the reconstructed pixel size and noise levels corresponding to 10 3 -10 7 photons per detector pixel prior to attenuation. The number of rays traced per detector element was varied from 1 to 16. Differences in the filtered backprojection images caused by changing the phantom matrix sizes and number of rays traced were assessed by calculating the difference between reconstructions based on the finest matrix and coarser matrix simulations. In noise free simulations, all phantom matrix sizes produced a measurable difference in comparison with the finest phantom matrix used. When even a small amount of noise was added to the projection data, the differences due to the phantom discretization were masked by the noise, and in all cases there was almost no improvement by using a phantom matrix that was more than twice as fine as the reconstruction matrix. No substantial improvement was achieved by tracing more than 4 rays per detector pixel

  7. Modeling fluid flow and heat transfer at Basin and Range faults: preliminary results for Leach hot springs, Nevada

    Science.gov (United States)

    López, Dina L.; Smith, Leslie; Storey, Michael L.; Nielson, Dennis L.

    1994-01-01

    The hydrothermal systems of the Basin and Range Province are often located at or near major range bounding normal faults. The flow of fluid and energy at these faults is affected by the advective transfer of heat and fluid from an to the adjacent mountain ranges and valleys, This paper addresses the effect of the exchange of fluid and energy between the country rock, the valley fill sediments, and the fault zone, on the fluid and heat flow regimes at the fault plane. For comparative purposes, the conditions simulated are patterned on Leach Hot Springs in southern Grass Valley, Nevada. Our simulations indicated that convection can exist at the fault plane even when the fault is exchanging significant heat and fluid with the surrounding country rock and valley fill sediments. The temperature at the base of the fault decreased with increasing permeability of the country rock. Higher groundwater discharge from the fault and lower temperatures at the base of the fault are favored by high country rock permabilities and fault transmissivities. Preliminary results suggest that basal temperatures and flow rates for Leach Hot Springs can not be simulated with a fault 3 km deep and an average regional heat flow of 150 mW/m2 because the basal temperature and mass discharge rates are too low. A fault permeable to greater depths or a higher regional heat flow may be indicated for these springs.

  8. Heat performance resulting from combined effects of radiation and mixed convection in a rectangular cavity ventilated by injection or suction

    Science.gov (United States)

    Ezzaraa, K.; Bahlaoui, A.; Arroub, I.; Raji, A.; Hasnaoui, M.; Naïmi, M.

    2018-05-01

    In this work, we investigated numerically heat transfer by mixed convection coupled to thermal radiation in a vented rectangular enclosure uniformly heated from below with a constant heat flux. The fresh fluid is admitted into the cavity by injection or suction, by means of two openings located on the lower part of both right and left vertical sides. Another opening is placed on the middle of the top wall to ensure the ventilation. Air, a radiatively transparent medium, is considered to be the cooling fluid. The inner surfaces, in contact with the fluid, are assumed to be gray, diffuse emitters and reflectors of radiation with identical emissivities. The effects of some pertinent parameters such as the Reynolds number, 300 ≤ Re ≤ 5000, and the emissivity of the walls, 0 ≤ ɛ ≤ 0.85, on flow and temperature patterns as well as on the heat transfer rate within the enclosure are presented for the two ventilation modes (injection and suction). The results indicate that the flow and thermal structures are affected by the thermal radiation for the two modes of imposed flow. However, the suction mode is found to be more favorable to the heat transfer in comparison with the injection one.

  9. Heat Flow and Gas Hydrates on the Continental Margin of India: Building on Results from NGHP Expedition 01

    Energy Technology Data Exchange (ETDEWEB)

    Anne Trehu; Peter Kannberg

    2011-06-30

    The Indian National Gas Hydrate Program (NGHP) Expedition 01 presented the unique opportunity to constrain regional heat flow derived from seismic observations by using drilling data in three regions on the continental margin of India. The seismic bottom simulating reflection (BSR) is a well-documented feature in hydrate bearing sediments, and can serve as a proxy for apparent heat flow if data are available to estimate acoustic velocity and density in water and sediments, thermal conductivity, and seafloor temperature. Direct observations of temperature at depth and physical properties of the sediment obtained from drilling can be used to calibrate the seismic observations, decreasing the uncertainty of the seismically-derived estimates. Anomalies in apparent heat flow can result from a variety of sources, including sedimentation, erosion, topographic refraction and fluid flow. We constructed apparent heat flow maps for portions of the Krishna-Godavari (K-G) basin, the Mahanadi basin, and the Andaman basin and modeled anomalies using 1-D conductive thermal models. Apparent heat flow values in the Krishna-Godavari (K-G) basin and Mahanadi basin are generally 0.035 to 0.055 watts per square meter (W/m{sup 2}). The borehole data show an increase in apparent heat flow as water depth increases from 900 to 1500 m. In the SW part of the seismic grid, 1D modeling of the effect of sedimentation on heat flow shows that {approx}50% of the observed increase in apparent heat flow with increasing water depth can be attributed to trapping of sediments behind a 'toe-thrust' ridge that is forming along the seaward edge of a thick, rapidly accumulating deltaic sediment pile. The remainder of the anomaly can be explained either by a decrease in thermal conductivity of the sediments filling the slope basin or by lateral advection of heat through fluid flow along stratigraphic horizons within the basin and through flexural faults in the crest of the anticline. Such flow

  10. Heat Flow and Gas Hydrates on the Continental Margin of India: Building on Results from NGHP Expedition 01

    Energy Technology Data Exchange (ETDEWEB)

    Trehu, Anne; Kannberg, Peter

    2011-06-30

    The Indian National Gas Hydrate Program (NGHP) Expedition 01 presented the unique opportunity to constrain regional heat flow derived from seismic observations by using drilling data in three regions on the continental margin of India. The seismic bottom simulating reflection (BSR) is a well-documented feature in hydrate bearing sediments, and can serve as a proxy for apparent heat flow if data are available to estimate acoustic velocity and density in water and sediments, thermal conductivity, and seafloor temperature. Direct observations of temperature at depth and physical properties of the sediment obtained from drilling can be used to calibrate the seismic observations, decreasing the uncertainty of the seismically-derived estimates. Anomalies in apparent heat flow can result from a variety of sources, including sedimentation, erosion, topographic refraction and fluid flow. We constructed apparent heat flow maps for portions of the Krishna-Godavari (K-G) basin, the Mahanadi basin, and the Andaman basin and modeled anomalies using 1-D conductive thermal models. Apparent heat flow values in the Krishna-Godavari (K-G) basin and Mahanadi basin are generally 0.035 to 0.055 watts per square meter (W/m2). The borehole data show an increase in apparent heat flow as water depth increases from 900 to 1500 m. In the SW part of the seismic grid, 1D modeling of the effect of sedimentation on heat flow shows that ~50% of the observed increase in apparent heat flow with increasing water depth can be attributed to trapping of sediments behind a "toe-thrust" ridge that is forming along the seaward edge of a thick, rapidly accumulating deltaic sediment pile. The remainder of the anomaly can be explained either by a decrease in thermal conductivity of the sediments filling the slope basin or by lateral advection of heat through fluid flow along stratigraphic horizons within the basin and through flexural faults in the crest of the anticline. Such flow probably plays a role in

  11. Fiscal 1999 report on result of the model project for waste heat recovery in hot blast stove; 1999 nendo netsufuro hainetsu kaishu model jigyo seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    For the purpose of curtailing energy consumption of the steel industry, a heavy energy consuming industry in China, a model project was carried out for waste heat recovery in a hot blast stove, with the fiscal 1999 results reported. In the process of this project, a heat exchanger for recovering heat is installed in the exhaust gas flue of a hot blast stove in ironworks, with sensible heat recovered through a heating medium. The heat exchanger for recovering heat and the preheating heat exchanger, which was installed in the main pipe for blast furnace gas and for combustion air, were connected by pressure piping, with the blast furnace gas and the combustion air preheated. In addition, a heating medium circulating pump for transporting the heating medium is installed, as are an expansion tank for absorbing expansion/contraction due to change in temperature, a heating medium storage tank for accepting the entire heating medium in the system for the maintenance of the equipment, and heating medium feeding pump, for example. This year, on the basis of the 'Agreement Annex', basic designs and detailed designs were performed for each equipment in the waste heat recovering equipment for the hot blast stove. Further, procurement and manufacturing were implemented for various component parts and devices of the waste heat recovering equipment. (NEDO)

  12. Phantom positioning variation in the Gamma Knife® Perfexion dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nathalia Almeida; Potiens, Maria da Penha Albuquerque [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Saraiva, Crystian [Hospital do Coracao, Sao Paulo, SP (Brazil)

    2015-07-01

    The use of small volume ionization chamber has become required for the dosimetry of equipment that use small radiation fields. A pinpoint ionization chamber is ideal for the dosimetry of a Gamma Knife® Perfexion (GKP) unit. In this work, this chamber was inserted into the phantom, and measurements were performed with the phantom in different positions, in order to verify if the change in the phantom positioning affects the dosimetry of the GKP. Three different phantom positions were performed. The variation in the result is within the range allowed for the dosimetry of a GKP equipment. (author)

  13. Design of a phantom multitrous for a gamma camera quality control

    International Nuclear Information System (INIS)

    Ben Krir, Wafa; Ben Ameur, Narjes

    2009-01-01

    In this study we presented the technique of scintigraphy in its various theoretical and practical aspects. We have also shown the importance the quality control procedure according to international standards, as NEMA. Starting from different phantoms currently used, developed according to standards, we designed our phantom. On the other part, this implementation has helped to highlight our expectations in Concerning the functionality of the phantom. Indeed, these results were very conclusive since they made it possible to make a very fast cost and quality control without ambiguity lower. We have thus proved the very advanced stage of reliability of our phantom.

  14. Energy saving potential of heat insulation solar glass: Key results from laboratory and in-situ testing

    International Nuclear Information System (INIS)

    Cuce, Erdem; Cuce, Pinar Mert; Young, Chin-Huai

    2016-01-01

    HISG (heat insulation solar glass) is a recently developed multi-functional glazing technology to mitigate energy consumption of buildings. HISG can generate electricity similar to conventional PV (photovoltaic) glazing products when exposed to sunlight, however it differs from them by having some extraordinary characteristic features such as thermal insulation, which is competitive with Argon filled triple glazed windows, acoustic comfort, remarkable energy saving potential and self-cleaning ability owing to TiO_2 nano coating. Within the scope of this research, latest results from laboratory and in-situ testing of HISG are presented in terms of its key role in mitigating heating and cooling demand of buildings as well as clean energy generation. Lighting and thermal comfort related parameters such as shading coefficient, UV, IR and visible light intensity are also investigated through the tests conducted in real operating conditions. It is achieved from the results that instant electricity generation of HISG is 16% higher than that of standard PV glazing owing to its nano layer reflective film. Shading coefficient of HISG is only 0.136, which provides almost 80% reduction in solar heat gain compared to ordinary glazing. Indoor air temperature measured from HISG test house in summer time is very close to the ambient temperature, whereas it is found to be 14.7 °C higher in ordinary glass test house due to greenhouse effect. Annual heating and cooling demand tests indicate that HISG provides 38 and 48% energy saving in heating and cooling season, respectively. - Highlights: • Nano layer reflective film of HISG enables 16% more power generation. • 80% of undesired outdoor thermal radiation is prevented by HISG. • HISG has a 100% UV blocking rate. • The shading coefficient of HISG is 0.136. • HISG provides 38 and 48% energy saving in heating and cooling season.

  15. 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)

  16. NUCLEAR HEATING IN LIF DOSEMETERS IN A FUSION NEUTRON FIELD, TRIAL OF DIRECT COMPARISON OF EXPERIMENTAL AND SIMULATED RESULTS.

    Science.gov (United States)

    Pohorecki, Wladyslaw; Obryk, Barbara

    2017-09-29

    The results of nuclear heating measured by means of thermoluminescent dosemeters (TLD-LiF) in a Cu block irradiated by 14 MeV neutrons are presented. The integral Cu experiment relevant for verification of copper nuclear data at neutron energies characteristic for fusion facilities was performed in the ENEA FNG Laboratory at Frascati. Five types of TLDs were used: highly photon sensitive LiF:Mg,Cu,P (MCP-N), 7LiF:Mg,Cu,P (MCP-7) and standard, lower sensitivity LiF:Mg,Ti (MTS-N), 7LiF:Mg,Ti (MTS-7) and 6LiF:Mg,Ti (MTS-6). Calibration of the detectors was performed with gamma rays in terms of air-kerma (10 mGy of 137Cs air-kerma). Nuclear heating in the Cu block was also calculated with the use of MCNP transport code Nuclear heating in Cu and air in TLD's positions was calculated as well. The nuclear heating contribution from all simulated by MCNP6 code particles including protons, deuterons, alphas tritons and heavier ions produced by the neutron interactions were calculated. A trial of the direct comparison between experimental results and results of simulation was performed. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Radiological equipment analyzed by specific developed phantoms and software

    International Nuclear Information System (INIS)

    Soto, M.; Campayo, J. M.; Mayo, P.; Verdu, G.; Rodenas, F.

    2010-10-01

    The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

  18. Radiological equipment analyzed by specific developed phantoms and software

    Energy Technology Data Exchange (ETDEWEB)

    Soto, M.; Campayo, J. M. [Logistica y Acondicionamientos Industriales SAU, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Mayo, P. [TITANIA Servicios Tecnologicos SL, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Verdu, G.; Rodenas, F., E-mail: m.soto@lainsa.co [ISIRYIM Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia (Spain)

    2010-10-15

    The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

  19. Investigation of radio frequency heating of dental implants made of titanium in 1.5 tesla and 3.0 tesla magnetic resonance procedure. Measurement of the temperature by using tissue-equivalent phantom

    International Nuclear Information System (INIS)

    Ideta, Takahiro; Yamazaki, Masaru; Kudou, Sadahiro; Higashida, Mitsuji; Nakazawa, Masami; Mori, Shintarou; Kaneda, Takashi

    2013-01-01

    Titanium (Ti) implants are increasingly being used for dental parts. There is no problem with the attraction of a static magnetic field for Ti in magnetic resonance imaging (MRI), since Ti is paramagnetic. However, there is a risk of radio frequency (RF) heat generation within Ti. 3.0 T-MRI scanners are becoming increasingly common. The specific absorption rate (SAR) of 3.0 T-MRI is quadruple that of SAR compared with 1.5 T-MRI due to its being proportional to the square of the strength of a static magnetic field. The effect of heat generation in 3.0 T-MRI can thus be greater than in 1.5 T-MRI. So, using 1.5 T and 3.0 T-MRI scanners, we measured the temperature of several Ti implants using the same scanning parameters during MRI scanning. Our measurements showed the rise in temperature of the Ti implants to be a maximum of 0.4degC. In this study, however, Ti in a human mouth was not directly measured, so we need to attempt to perform MRI carefully on patients with Ti implants. (author)

  20. A Software Phantom : Application in Digital Tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Lazos, D; Kolitsi, Z; Badea, C; Pallikarakis, N [Medical Physics Laboratory, School of Medicine, Univercity of Patras (Greece)

    1999-12-31

    A software phantom intended to be used in radiographic applications has been developed. The application was used for research in the field of Digital Tomosynthesis and specifically for studying tomographic noise removal methods. The application consists of a phantom design and a phantom imaging module. The radiation-matter interaction is based on the exponential relation of attenuation. Projections are formed by simulated irradiation with selectable geometrical parameters, source spectrum and detector response. Phantoms are defined either as sets containing certain geometrical objects or as groups of voxels. Comparison with real projections taken from a physical phantom with identical geometry and composition with the simulated one, showed good approximation with improved contrast due to the absence of scatter in the simulated projections. The software phantom proved to be a very useful tool for DTS investigations. Further development to include scatter is expected to expand the use of the application to more areas in radiological imaging research. (author) 4 refs., 3 figs

  1. A Software Phantom : Application in Digital Tomosynthesis

    International Nuclear Information System (INIS)

    Lazos, D.; Kolitsi, Z.; Badea, C.; Pallikarakis, N.

    1998-01-01

    A software phantom intended to be used in radiographic applications has been developed. The application was used for research in the field of Digital Tomosynthesis and specifically for studying tomographic noise removal methods. The application consists of a phantom design and a phantom imaging module. The radiation-matter interaction is based on the exponential relation of attenuation. Projections are formed by simulated irradiation with selectable geometrical parameters, source spectrum and detector response. Phantoms are defined either as sets containing certain geometrical objects or as groups of voxels. Comparison with real projections taken from a physical phantom with identical geometry and composition with the simulated one, showed good approximation with improved contrast due to the absence of scatter in the simulated projections. The software phantom proved to be a very useful tool for DTS investigations. Further development to include scatter is expected to expand the use of the application to more areas in radiological imaging research. (author)

  2. Profile Modifications Resulting from Early High-harmonic Fast Wave heating in NSTX

    International Nuclear Information System (INIS)

    Mendard, J.E.; LeBlanc, Wilson J.R.; Sabbagh, S.A.; Stutman, D.; Swain, D.W.

    2001-01-01

    Experiments have been performed in the National Spherical Torus Experiment (NSTX) to inject high harmonic fast wave (HHFW) power early during the plasma current ramp-up in an attempt to reduce the current penetration rate to raise the central safety factor during the flattop phase of the discharge. To date, up to 2 MW of HHFW power has been coupled to deuterium plasmas as early as t = 50 ms using the slowest interstrap phasing of k|| approximately equals 14 m(superscript)-1 (nf = 24). Antenna-plasma gap scans have been performed and find that for small gaps (5-8 cm), electron heating is observed with relatively small density rises and modest reductions in current penetration rate. For somewhat larger gaps (10-12 cm), weak electron heating is observed but with a spontaneous density rise at the plasma edge similar to that observed in NSTX H-modes. In the larger gap configuration, EFIT code reconstructions (without MSE [motional Stark effect]) find that resistive flux consumption is reduced as much as 30%, the internal inductance is maintained below 0.6 at 1 MA into the flattop, q(0) is increased significantly, and the MHD stability character of the discharges is strongly modified

  3. Heat storage in the Hettangian aquifer in Berlin - results from a column experiment

    Science.gov (United States)

    Milkus, Chri(Sch)augott

    2015-04-01

    Aquifer Thermal Energy Storage (ATES) is a sustainable alternative for storage and seasonal availability of thermal energy. However, its impact on the subsurface flow regime is not well known. In Berlin (Germany), the Jurassic (Hettangian) sandstone aquifer with highly mineralized groundwater (TDS 27 g/L) is currently used for heat storage. The aim of this study was to examine the hydrogeochemical changes that are caused by the induced temperature shift and its effects on the hydraulic permeability of the aquifer. Column experiments were conducted, in which stainless steel columns were filled with sediment from the aquifer and flushed with native groundwater for several weeks. The initial temperature of the experiment was 20°C, comparable to the in-situ conditions within the aquifer. After reaching equilibrium between sediment and water, the temperature was increased to simulate heating of the aquifer. During the experiment, physical and chemical parameters (pH, ORP, dissolved oxygen and dissolved carbon dioxide) were measured at the outflow of the column and the effluent water was sampled. Using a Scanning Electron Microscope, the deposition of precipitated minerals and biofilm on sediment grains was analyzed. Changes in hydraulic properties of the sediment were studied by the use of tracer tests with Uranin.

  4. Side-by-Side Testing of Water Heating Systems: Results from the 2013–2014 Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Colon, Carlos [Florida Solar Energy Center, Cocoa, FL (United States). Building America Partnership for Improved Residential Construction (BA-PIRC)

    2017-07-01

    The Florida Solar Energy Center (FSEC) completed a fourth year-long evaluation on residential hot water heating systems in a laboratory environment (east central Florida, hot-humid climate). The evaluation studied the performance of five hot water systems (HWS) plus a reference baseline system for each fuel, (i.e., electric and natural gas). Electric HWS consisted of two residential electric heat pump water heaters (HPWHs, 60 and 80 gallons), a solar thermal system using a polymer absorber (glazed) collector with 80-gallon storage and a duplicate 50-gallon standard electric water heater with added cap and wrap insulation. Baseline performance data were collected from a standard 50-gallon electric water heater of minimum code efficiency to compare energy savings. Similarly, a standard 40-gallon upright vented natural gas water heater served as baseline for the natural gas fuel category. The latter, having a larger jacket diameter [18 in., with an energy factor (EF) of 0.62] with increased insulation, replaced a former baseline (17 in. diameter, EF = 0.59) that served during three previous testing rotations (2009–2013). A high-efficiency, condensing natural gas hybrid water heater with 27-gallon buffered tank was also tested and compared against the gas baseline. All systems underwent testing simultaneously side-by-side under the criteria specified elsewhere in this report.

  5. Dual Energy Tomosynthesis breast phantom imaging

    Science.gov (United States)

    Koukou, V.; Martini, N.; Fountos, G.; Messaris, G.; Michail, C.; Kandarakis, I.; Nikiforidis, G.

    2017-12-01

    Dual energy (DE) imaging technique has been applied to many theoretical and experimental studies. The aim of the current study is to evaluate dual energy in breast tomosynthesis using commercial tomosynthesis system in terms of its potential to better visualize microcalcifications (μCs). The system uses a tungsten target X-ray tube and a selenium direct conversion detector. Low-energy (LE) images were acquired at different tube voltages (28, 30, 32 kV), while high-energy images at 49 kV. Fifteen projections, for the low- and high-energy respectively, were acquired without grid while tube scanned continuously. Log-subtraction algorithm was used in order to obtain the DE images with the weighting factor, w, derived empirically. The subtraction was applied to each pair of LE and HE slices after reconstruction. The TORMAM phantom was imaged with the different settings. Four regions-of-interest including μCs were identified in the inhomogeneous part of the phantom. The μCs in DE images were more clearly visible compared to the low-energy images. Initial results showed that DE tomosynthesis imaging is a promising modality, however more work is required.

  6. Characterization of tracked radiofrequency ablation in phantom

    International Nuclear Information System (INIS)

    Chen, Chun-Cheng R.; Miga, Michael I.; Galloway, Robert L.

    2007-01-01

    In radiofrequency ablation (RFA), successful therapy requires accurate, image-guided placement of the ablation device in a location selected by a predictive treatment plan. Current planning methods rely on geometric models of ablations that are not sensitive to underlying physical processes in RFA. Implementing plans based on computational models of RFA with image-guided techniques, however, has not been well characterized. To study the use of computational models of RFA in planning needle placement, this work compared ablations performed with an optically tracked RFA device with corresponding models of the ablations. The calibration of the tracked device allowed the positions of distal features of the device, particularly the tips of the needle electrodes, to be determined to within 1.4±0.6 mm of uncertainty. Ablations were then performed using the tracked device in a phantom system based on an agarose-albumin mixture. Images of the sliced phantom obtained from the ablation experiments were then compared with the predictions of a bioheat transfer model of RFA, which used the positional data of the tracked device obtained during ablation. The model was demonstrated to predict 90% of imaged pixels classified as being ablated. The discrepancies between model predictions and observations were analyzed and attributed to needle tracking inaccuracy as well as to uncertainties in model parameters. The results suggest the feasibility of using finite element modeling to plan ablations with predictable outcomes when implemented using tracked RFA

  7. Solid tissue simulating phantoms having absorption at 970 nm for diffuse optics

    Science.gov (United States)

    Kennedy, Gordon T.; Lentsch, Griffin R.; Trieu, Brandon; Ponticorvo, Adrien; Saager, Rolf B.; Durkin, Anthony J.

    2017-07-01

    Tissue simulating phantoms can provide a valuable platform for quantitative evaluation of the performance of diffuse optical devices. While solid phantoms have been developed for applications related to characterizing exogenous fluorescence and intrinsic chromophores such as hemoglobin and melanin, we report the development of a poly(dimethylsiloxane) (PDMS) tissue phantom that mimics the spectral characteristics of tissue water. We have developed these phantoms to mimic different water fractions in tissue, with the purpose of testing new devices within the context of clinical applications such as burn wound triage. Compared to liquid phantoms, cured PDMS phantoms are easier to transport and use and have a longer usable life than gelatin-based phantoms. As silicone is hydrophobic, 9606 dye was used to mimic the optical absorption feature of water in the vicinity of 970 nm. Scattering properties are determined by adding titanium dioxide, which yields a wavelength-dependent scattering coefficient similar to that observed in tissue in the near-infrared. Phantom properties were characterized and validated using the techniques of inverse adding-doubling and spatial frequency domain imaging. Results presented here demonstrate that we can fabricate solid phantoms that can be used to simulate different water fractions.

  8. Research and development of selected components of the high-temperature reactor for process heat generation - results and their application

    International Nuclear Information System (INIS)

    Theymann, W.; Lange, G.

    1989-01-01

    For the process heat supplying high-temperature reactor (PNP) a comprehensive research and development program was performed. Investigations in three fields of the program are reported: heat transfer, gas flow guidance components, and seismic properties of the core structure. Results are presented for the statistics of heat transfer in the core and for heat transfer under operational conditions of a PNP-plant. Further topics are cooling of the side reflector, hot gas mixing in the core bottom region, optimization of inlet flow into the steam generator, and flow tests on a large diameter shut-off valve. Performance tests on hot gas insulations in a special test facility are described as well as tests on connecting elements for coaxial ducts. The measured data on dynamic excitation of the pebble bed with the SAMSON test facility allow an analytical description of the pebble bed core with respect to seismic behaviour. The results of experiments and calculations, using the computer codes CRUNCH-1D and -2D, for seismic excitation of the suspended top reflector are discussed. The seismic tests will be completed in 1989 with the side reflector investigations. A comprehensive seismic verification will then be available. (orig.)

  9. Design and evaluation of corn starch-bonded Rhizophora spp. particleboard phantoms for SPECT/CT imaging

    Science.gov (United States)

    Hamid, Puteri Nor Khatijah Abd; Yusof, Mohd Fahmi Mohd; Aziz Tajuddin, Abd; Hashim, Rokiah; Zainon, Rafidah

    2018-01-01

    The aim of this study was to design and evaluate of corn starch-bonded Rhizophora spp. particleboards as phantom for SPECT/CT imaging. The phantom was designed according to the Jaszczak phantom commonly used in SPECT imaging with dimension of 22 cm diameter and 18 cm length. Six inserts with different diameter were made for insertion of vials filled with 1.6 µCi/ml of 99mTc unsealed source. The particleboard phantom was scanned using SPECT/CT imaging protocol. The contrast of each vial for particleboards phantom were calculated based on the ratio of counts in radionuclide volume and phantom background and compared to Perspex® and water phantom. The results showed that contrast values for each vial in particleboard phantomis near to 1.0 and in good agreement with Perspex® and water phantoms as common phantom materials for SPECT/CT. The paired sample t-test result showed no significant difference of contrast values between images in particleboard phantoms and that in water. The overall results showed the potential of corn starch-bonded Rhizophora spp. as phantom for quality control and dosimetry works in SPECT/CT imaging.

  10. The internal radiation dose calculations based on Chinese mathematical phantom

    International Nuclear Information System (INIS)

    Wang Haiyan; Li Junli; Cheng Jianping; Fan Jiajin

    2006-01-01

    The internal radiation dose calculations built on Chinese facts become more and more important according to the development of nuclear medicine. the MIRD method developed and consummated by the society of Nuclear Medicine (America) is based on the European and American mathematical phantom and can't fit Chinese well. The transport of γ-ray in the Chinese mathematical phantom was simulated with Monte Carlo method in programs as MCNP4C. the specific absorbed fraction (Φ) of Chinese were calculated and the Chinese Φ database was created. The results were compared with the recommended values by ORNL. the method was proved correct by the coherence when the target organ was the same with the source organ. Else, the difference was due to the different phantom and the choice of different physical model. (authors)

  11. A Dynamic Compliance Cervix Phantom Robot for Latent Labor Simulation.

    Science.gov (United States)

    Luk, Michelle Jennifer; Lobb, Derek; Smith, James Andrew

    2018-05-09

    Physical simulation systems are commonly used in training of midwifery and obstetrics students, but none of these systems offers a dynamic compliance aspect that would make them more truly representative of cervix ripening. In this study, we introduce a unique soft robot phantom that simulates the cervix softening during the latent labor phase of birth. This proof-of-concept robotic phantom can be dilated by 1 cm and effaced by 35% through the application of a Foley catheter-like loading mechanism. Furthermore, psychophysics trials demonstrate how untrained subjects can identify hard and soft states of the phantom with specificities of 91% and 87%, respectively. Both results indicated the appropriateness for application of this soft robot technology to birth training simulators.

  12. Dosimetry using radiochromic film and planning algorithms in heterogeneous phantoms

    International Nuclear Information System (INIS)

    Leite, Vinicius Freitas

    2012-01-01

    This work analyzes, through the study of the interaction of electromagnetic radiation with matter, two schemes of heterogeneous phantoms schematised to simulate real cases of planning with different electronic densities through the Pencil Beam, Collapsed Cone and Analytical Anisotropic Algorithm algorithms and compare with measurements Of relative absorbed dose in an IBA CC13 ionization chamber and Gafchromic® EBT2 radiochromic film. Epichlorohydrin rubber and its compatibility in comparison with human bone has also been evaluated. The assembly of the heterogeneous phantoms was feasible and the results regarding the density and attenuation of the rubber presented consistent values. However, the study of PDPs in constructed phantoms showed a considerable percentage discrepancy between measurements and planning

  13. 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...

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-03-01

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

  16. Heat transfer and solidification processes of alloy melt with undercooling: I. Experimental results

    International Nuclear Information System (INIS)

    Yoshioka, Hideaki; Tada, Yukio; Kunimine, Kanji; Furuichi, Taira; Hayashi, Yujiro

    2006-01-01

    The solidification process of Pb-Sn and Bi-Sn alloy melts is discussed to obtain a basic understanding of the essential phenomena of solidification with undercooling. First, from macroscopic observations, it is shown that the solidification process consists of the following three stages: (1) free growth with recalescence dissipation of thermal undercooling (2) expansion of crystals with the relaxation of constitutional undercooling or with the recovering process of interrupted quasi-steady heat conduction, and (3) equilibrium solidification. The specific features of free growth under non-uniform undercooling are also shown by comparison with the Lipton, Glicksman, and Kurz model. Next, from microscopic observations, the distribution of the solute concentration and the change of crystal morphology in the solidified materials were investigated quantitatively using scanning electron microscopy and energy-dispersive spectroscopy. Finally, the solidification path during the above three fundamental processes is dynamically represented on phase diagrams

  17. Ventilation System Type and the Resulting Classroom Temperature and Air Quality During Heating Season

    DEFF Research Database (Denmark)

    Gao, Jie; Wargocki, Pawel; Wang, Yi

    2014-01-01

    The present study investigated how different ventilation system types influence classroom temperature and air quality. Five classrooms were selected in the same school. They were ventilated by manually operable windows, manually operable windows with exhaust fan, automatically operable windows...... with and without exhaust fan and by mechanical ventilation system. Temperature, relative humidity, carbon dioxide (CO2) concentration and opening of windows were continuously monitored for one month during heating season in 2012. Classroom with manually operable windows had the highest carbon dioxide concentration...... levels so that the estimated ventilation rate was the lowest compared with the classrooms ventilated with other systems. Temperatures were slightly lower in classroom ventilated by manually operable windows with exhaust fan. Windows were opened seldom even in the classroom ventilated by manually operable...

  18. Effective dose measurement at workplaces within an instrumented anthropomorphic phantom

    International Nuclear Information System (INIS)

    Villagrasa, C.; Darreon, J.; Martin-Burtat, N.; Clairand, I.; Colin, J.; Fontbonne, J. M.

    2011-01-01

    The Laboratory of Ionizing Radiation Dosimetry of the IRSN (France) is developing an instrumented anthropomorphic phantom in order to measure the effective dose for photon fields at workplaces. This anthropomorphic phantom will be equipped with small active detectors located inside at chosen positions. The aim of this paper is to present the development of these new detectors showing the results of the characterisation of the prototype under metrological conditions. New evaluations of the effective dose for standard and non-homogenous irradiation configurations taking into account the real constraints of the project have been done validating the feasibility and utility of the instrument. (authors)

  19. Phantom-based interactive simulation system for dental treatment training.

    Science.gov (United States)

    Sae-Kee, Bundit; Riener, Robert; Frey, Martin; Pröll, Thomas; Burgkart, Rainer

    2004-01-01

    In this paper, we propose a new interactive simulation system for dental treatment training. The system comprises a virtual reality environment and a force-torque measuring device to enhance the capabilities of a passive phantom of tooth anatomy in dental treatment training processes. The measuring device is connected to the phantom, and provides essential input data for generating the graphic animations of physical behaviors such as drilling and bleeding. The animation methods of those physical behaviors are also presented. This system is not only able to enhance interactivity and accessibility of the training system compared to conventional methods but it also provides possibilities of recording, evaluating, and verifying the training results.

  20. Heat Stress

    Science.gov (United States)

    ... Publications and Products Programs Contact NIOSH NIOSH HEAT STRESS Recommend on Facebook Tweet Share Compartir OSHA-NIOSH ... hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational ...

  1. Preventing damage in heating systems. Corrosion resulting from water in heating systems; Schaeden in Heizungsanlagen vermeiden. Korrosion in Verbindung mit Heizungswasser

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, M. [Hannemann Wassertechnik Deutschland, Erding (Germany)

    2004-02-01

    Nearly all heating systems today use water as heating fluid. It is therefore important to know about the properties of this heat carrier fluid and about its interactions with heating system materials. This contribution discusses the main characteristics of common types of water and their effects on the heating systems. (orig.) [German] Praktisch in jeder Heizungsanlage wird Wasser als Waermetraeger verwendet. Von daher ist es ratsam, Eigenschaften dieses Waermetraegers und seine Wechselwirkungen mit Heizungswerkstoffen zu kennen. Der nachfolgende Beitrag behandelt die wichtigsten Eigenschaften gebraeuchlicher Waesser und deren Auswirkungen auf die Heizungsanlagen. (orig.)

  2. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: experimental design and preliminary results.

    Science.gov (United States)

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

  3. Thermal Response Testing Results of Different Types of Borehole Heat Exchangers: An Analysis and Comparison of Interpretation Methods

    Directory of Open Access Journals (Sweden)

    Angelo Zarrella

    2017-06-01

    Full Text Available The design phase of ground source heat pump systems is an extremely important one as many of the decisions made at that time can affect the system’s energy performance as well as installation and operating costs. The current study examined the interpretation of thermal response testing measurements used to evaluate the equivalent ground thermal conductivity and thus to design the system. All the measurements were taken at the same geological site located in Molinella, Bologna (Italy where a variety of borehole heat exchangers (BHEs had been installed and investigated within the project Cheap-GSHPs (Cheap and efficient application of reliable Ground Source Heat exchangers and Pumps of the European Union’s Horizon 2020 research and innovation program. The measurements were initially analyzed in accordance with the common interpretation based on the first-order approximation of the solution for the infinite line source model and then by utilizing the complete solutions of both the infinite line and cylinder source models. An inverse numerical approach based on a detailed model that considers the current geometry of the BHE and the axial heat transfer as well as the effect of weather on the ground surface was also used. Study findings revealed that the best result was generally obtained using the inverse numerical interpretation.

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

    NARCIS (Netherlands)

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

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

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

    Science.gov (United States)

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

    2016-10-01

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

  6. Realistic deformable 3D numeric phantom for transcutaneous ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Fernando Mitsuyama; Moraes, Matheus Cardoso; Furuie, Sergio Shiguemi, E-mail: fernando.okara@gmail.com [Universidade de Sao Paulo (USP), SP (Brazil). Escola de Engenharia

    2017-01-15

    Introduction: Numerical phantoms are important tools to design, calibrate and evaluate several methods in various image-processing applications, such as echocardiography and mammography. We present a framework for creating ultrasound numerical deformable phantoms based on Finite Element Method (FEM), Linear Isomorphism and Field II. The proposed method considers that the scatterers map is a property of the tissue; therefore, the scatterers should move according to the tissue strain. Methods: First, a volume representing the target tissue is loaded. Second, parameter values, such as Young's Modulus, scatterers density, attenuation and scattering amplitudes are inserted for each different regions of the phantom. Then, other parameters related to the ultrasound equipment, such as ultrasound frequency and number of transducer elements, are also defined in order to perform the ultrasound acquisition using Field II. Third, the size and position of the transducer and the pressures that are applied against the tissue are defined. Subsequently, FEM is executed and deformation is computed. Next, 3D linear isomorphism is performed to displace the scatterers according to the deformation. Finally, Field II is carried out to generate the non-deformed and deformed ultrasound data. Results: The framework is evaluated by comparing strain values obtained the numerical simulation and from the physical phantom from CIRS. The mean difference between both phantoms is lesser than 10%. Conclusion: The acoustic and deformation outcomes are similar to those obtained using a physical phantom. This framework led to a tool, which is available online and free of charges for educational and research purposes. (author)

  7. Design and development of an ultrasound calibration phantom and system

    Science.gov (United States)

    Cheng, Alexis; Ackerman, Martin K.; Chirikjian, Gregory S.; Boctor, Emad M.

    2014-03-01

    Image-guided surgery systems are often used to provide surgeons with informational support. Due to several unique advantages such as ease of use, real-time image acquisition, and no ionizing radiation, ultrasound is a common medical imaging modality used in image-guided surgery systems. To perform advanced forms of guidance with ultrasound, such as virtual image overlays or automated robotic actuation, an ultrasound calibration process must be performed. This process recovers the rigid body transformation between a tracked marker attached to the ultrasound transducer and the ultrasound image. A phantom or model with known geometry is also required. In this work, we design and test an ultrasound calibration phantom and software. The two main considerations in this work are utilizing our knowledge of ultrasound physics to design the phantom and delivering an easy to use calibration process to the user. We explore the use of a three-dimensional printer to create the phantom in its entirety without need for user assembly. We have also developed software to automatically segment the three-dimensional printed rods from the ultrasound image by leveraging knowledge about the shape and scale of the phantom. In this work, we present preliminary results from using this phantom to perform ultrasound calibration. To test the efficacy of our method, we match the projection of the points segmented from the image to the known model and calculate a sum squared difference between each point for several combinations of motion generation and filtering methods. The best performing combination of motion and filtering techniques had an error of 1.56 mm and a standard deviation of 1.02 mm.

  8. Polyvinyl chloride plastisol breast phantoms for ultrasound imaging.

    Science.gov (United States)

    de Carvalho, Isabela Miller; De Matheo, Lucas Lobianco; Costa Júnior, José Francisco Silva; Borba, Cecília de Melo; von Krüger, Marco Antonio; Infantosi, Antonio Fernando Catelli; Pereira, Wagner Coelho de Albuquerque

    2016-08-01

    Ultrasonic phantoms are objects that mimic some features of biological tissues, allowing the study of their interactions with ultrasound (US). In the diagnostic-imaging field, breast phantoms are an important tool for testing performance and optimizing US systems, as well as for training medical professionals. This paper describes the design and manufacture of breast lesions by using polyvinyl chloride plastisol (PVCP) as the base material. Among the materials available for this study, PVCP was shown to be stable, durable, and easy to handle. Furthermore, it is a nontoxic, nonpolluting, and low-cost material. The breast's glandular tissue (image background) was simulated by adding graphite powder with a concentration of 1% to the base material. Mixing PVCP and graphite powder in differing concentrations allows one to simulate lesions with different echogenicity patterns (anechoic, hypoechoic, and hyperechoic). From this mixture, phantom materials were obtained with speed of sound varying from 1379.3 to 1397.9ms(-1) and an attenuation coefficient having values between 0.29 and 0.94dBcm(-1) for a frequency of 1MHz at 24°C. A single layer of carnauba wax was added to the lesion surface in order to evaluate its applicability for imaging. The images of the phantoms were acquired using commercial ultrasound equipment; a specialist rated the images, elaborating diagnoses representative of both benign and malignant lesions. The results indicated that it was possible to easily create a phantom by using low-cost materials, readily available in the market and stable at room temperature, as the basis of ultrasonic phantoms that reproduce the image characteristics of fatty breast tissue and typical lesions of the breast. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Introduction of a stack-phantom for PET

    International Nuclear Information System (INIS)

    Jonsson, C.; Schnell, P.O.; Jacobsson, H.; Engelin, L.; Danielsson, A.M.; Johansson, L.; Larsson, S.A.; Pagani, M.; Stone-Elander, S.

    2002-01-01

    Aim: We have previously developed a new flexible phantom system for SPECT, i.e. 'the stack phantom' (Eur. J. Nucl. Med. 27, No.2, 131-139, 2000). The unique feature of this phantom system is that it allows studies with, as well as without major degrading impacts from photon attenuation and Compton scattering. The specific aim of this work was to further develop the system with special reference to PET. Material and methods: The principle of the phantom concept is discrete sampling of 3D objects by a series of equidistant 2D planes. The 2D planes are a digitised set of 2D sections, representing the radioactivity distribution in the object of interest. Using a grey scale related to the radioactivity concentration, selected images are printed by radioactive ink on thin paper sheets and stacked into the 3D structure with low-density or with tissue equivalent material in between. Using positron emitting radionuclides, the paper sheets alone may not be sufficiently thick to avoid annihilation losses due to escaping positrons. In order to investigate the amount of additional material needed, a spot of radioactivity ( 18 F) was printed out and subsequently covered by adding thin plastic films (0.055mm) on both sides of the paper. Short PET scans (ECAT 921) were performed and the count-rate was registered after each additional layer of plastic cover. A first prototype, a cylindrical cold-spot phantom was constructed on the basis of these results. Nine identical sheets were printed out and first mounted in between 4 mm plates of polystyrene (density 1.04 g/cm 3 ). After a PET-scan, the paper sheets were re-mounted in between a low-density material (Divinycell, H30, density 0.03 g/cm 3 ) before repeating the PET scan. Results: For 18 F, the number of registered annihilation photons increased with increasing number of plastic sheets from 70% for the pure paper sheet to about 100% with 0.5 mm plastic cover on each side. PET of the low-density stacked cold spot phantom

  10. Development of PIMAL: Mathematical Phantom with Moving Arms and Legs

    Energy Technology Data Exchange (ETDEWEB)

    Akkurt, Hatice [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eckerman, Keith F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2007-05-01

    The computational model of the human anatomy (phantom) has gone through many revisions since its initial development in the 1970s. The computational phantom model currently used by the Nuclear Regulatory Commission (NRC) is based on a model published in 1974. Hence, the phantom model used by the NRC staff was missing some organs (e.g., neck, esophagus) and tissues. Further, locations of some organs were inappropriate (e.g., thyroid).Moreover, all the computational phantoms were assumed to be in the vertical-upright position. However, many occupational radiation exposures occur with the worker in other positions. In the first phase of this work, updates on the computational phantom models were reviewed and a revised phantom model, which includes the updates for the relevant organs and compositions, was identified. This revised model was adopted as the starting point for this development work, and hence a series of radiation transport computations, using the Monte Carlo code MCNP5, was performed. The computational results were compared against values reported by the International Commission on Radiation Protection (ICRP) in Publication 74. For some of the organs (e.g., thyroid), there were discrepancies between the computed values and the results reported in ICRP-74. The reasons behind these discrepancies have been investigated and are discussed in this report.Additionally, sensitivity computations were performed to determine the sensitivity of the organ doses for certain parameters, including composition and cross sections used in the simulations. To assess the dose for more realistic exposure configurations, the phantom model was revised to enable flexible positioning of the arms and legs. Furthermore, to reduce the user time for analyses, a graphical user interface (GUI) was developed. The GUI can be used to visualize the positioning of the arms and legs as desired posture is achieved to generate the input file, invoke the computations, and extract the organ dose

  11. Results of high heat flux qualification tests of W monoblock components for WEST

    Science.gov (United States)

    Greuner, H.; Böswirth, B.; Lipa, M.; Missirlian, M.; Richou, M.

    2017-12-01

    One goal of the WEST project (W Environment in Steady-state Tokamak) is the manufacturing, quality assessment and operation of ITER-like actively water-cooled divertor plasma facing components made of tungsten. Six W monoblock plasma facing units (PFUs) from different suppliers have been successfully evaluated in the high heat flux test facility GLADIS at IPP. Each PFU is equipped with 35 W monoblocks of an ITER-like geometry. However, the W blocks are made of different tungsten grades and the suppliers applied different bonding techniques between tungsten and the inserted Cu-alloy cooling tubes. The intention of the HHF test campaign was to assess the manufacturing quality of the PFUs on the basis of a statistical analysis of the surface temperature evolution of the individual W monoblocks during thermal loading with 100 cycles at 10 MW m-2. These tests confirm the non-destructive examinations performed by the manufacturer and CEA prior to the installation of the WEST platform, and no defects of the components were detected.

  12. Focus on Bioenergy in the electricity and heat market. Project results 2015-2016

    International Nuclear Information System (INIS)

    Thraen, Daniela; Pfeiffer, Diana

    2017-01-01

    The report covers the following contributions: DeHoGas - sustainable local wood gasification plant with coupled micro gas turbine; SEVERA - sensor technique for efficient fermentation og biogenic residuals and wastes; FuelBand - extension of the fuel band of modern biomass combustion; REPOWERING - measures for efficiency improvement for the existing plants; PROKOSYS - processes, components and systems for flexible operation of biogas plants using biogenic residuals and wastes; Carola - electrostatic finest particle separator for flexible adaptation to biomass vessels; HydoCon - hydrolysis container - flexible plant components for substrate usage improvement in biogas plants; EFFIGEST - efficiency improvement in poultry manure fermentation using modified straw fractions and process integrated production of marketable fertilizer; FLUHKE - dry low-temperature entrained flow gasification with bio-coals from hydrothermal carbonization for local electricity and heat production with motor-cogeneration; REMISBIO - measures for emissions reduction of bio gas plants - catalyst test; Mini-bio-cogeneration - readiness of prototype for decentralized gasification of residual pellets for serial production; IbeKEt - innovative communal demand-adaptive energy carrier concept; Regiobalance - flexible bioenergy as regional compensation option in the German electricity market; FLEXHKW - flexible operation of cogeneration plants.

  13. Starch nanoparticles resulting from combination of dry heating under mildly acidic conditions and homogenization.

    Science.gov (United States)

    Kim, Jong Hun; Kim, Jiyeon; Park, Eun Young; Kim, Jong-Yea

    2017-07-15

    To modify starch granular structure, normal maize starch was subjected to dry heating with various amounts of 1.0M HCl (1.2, 1.4 or 1.6mL) and different treatment times (2, 4 or 8h). For all reaction conditions, at least 80% of the starch substance was recovered, and amylose and amylopectin B1 chains were preferentially cleaved. As acidic condition and/or treatment time increased, the treated granules were readily fragmented by homogenization. The treatment appeared to alter short-range crystalline structure (FT-IR), but long-range crystalline structure (XRD) remained intact. Homogenization for 60min fragmented the treated starch granules (subjected to reaction condition of 1.4mL/4h, 1.6mL/2h, and 1.6mL/4h) into nanoparticles consisting of individual platelet-like and spherical particles with diameters less than 100nm. However, the fragmentation caused obvious damage in the long-range crystalline structure of starch nanoparticles, while the short-range chain associations remained relatively intact. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Results of high heat flux qualification tests of W monoblock components for WEST

    International Nuclear Information System (INIS)

    Greuner, H; Böswirth, B; Lipa, M; Missirlian, M; Richou, M

    2017-01-01

    One goal of the WEST project (W Environment in Steady-state Tokamak) is the manufacturing, quality assessment and operation of ITER-like actively water-cooled divertor plasma facing components made of tungsten. Six W monoblock plasma facing units (PFUs) from different suppliers have been successfully evaluated in the high heat flux test facility GLADIS at IPP. Each PFU is equipped with 35 W monoblocks of an ITER-like geometry. However, the W blocks are made of different tungsten grades and the suppliers applied different bonding techniques between tungsten and the inserted Cu-alloy cooling tubes. The intention of the HHF test campaign was to assess the manufacturing quality of the PFUs on the basis of a statistical analysis of the surface temperature evolution of the individual W monoblocks during thermal loading with 100 cycles at 10 MW m −2 . These tests confirm the non-destructive examinations performed by the manufacturer and CEA prior to the installation of the WEST platform, and no defects of the components were detected. (paper)

  15. DCH-2: Results from the second experiment performed in the Surtsey Direct Heating Test Facility

    International Nuclear Information System (INIS)

    Tarbell, W.W.; Nichols, R.T.; Brockmann, J.E.; Ross, J.W.; Oliver, M.S.; Lucero, D.A.

    1988-01-01

    This test involved 80 kg of molten core debris simulant ejected under pressure into a 1:10 linear scale model of a reactor cavity. The apparatus was placed in the Surtsey Direct Heating Test Facility to allow direct measurement of the temperature and pressure rise of the contained atmosphere. The molten material was ejected from the cavity as a dense cloud of particles and gas. The dispersed debris caused a rapid pressurization of the 103-m 3 atmosphere. Peak pressures ranged from 0.22 to 0.31 MPa above the ambient level. Peak temperatures were from 759 0 C to 1335 0 C, with the highest values recorded near the top of the chamber. Much of the debris (∼70%) was found adhered to the top and sides of the steel chamber. The pattern of the retained material suggested that the debris field propagated around the chamber following the contour of the vessel. Aerosol measurements indicated that ∼1% to ∼6.6% of the ejected mass was in the size range less than 10μm aerodynamic diameter. 8 refs., 28 figs., 6 tabs

  16. Experimental evaluation of the thermal properties of two tissue equivalent phantom materials.

    Science.gov (United States)

    Craciunescu, O I; Howle, L E; Clegg, S T

    1999-01-01

    Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for computing the power and/or temperature distributions. For the numerical simulations to be accurate, the electrical and thermal properties of the materials that form the phantom should be accurately characterized. This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the electrical properties of human muscle. Particularities of the two samples required the design of alternative measuring techniques for the specific heat and thermal conductivity. For the specific heat, a calorimeter method is used. For the thermal diffusivity, a method derived from the standard guarded comparative-longitudinal heat flow technique was used for both materials. For the 'muscle'-like material, the thermal conductivity, density and specific heat at constant pressure were measured as: k = 0.31 +/- 0.001 W(mK)(-1), p = 1026 +/- 7 kgm(-3), and c(p) = 4584 +/- 107 J(kgK)(-1). For the 'fat'-like material, the literature reports on the density and specific heat such that only the thermal conductivity was measured as k = 0.55 W(mK)(-1).

  17. Characterisation of an anthropomorphic chest phantom for dose measurements in radiology beams

    Science.gov (United States)

    Henriques, L. M. S.; Cerqueira, R. A. D.; Santos, W. S.; Pereira, A. J. S.; Rodrigues, T. M. A.; Carvalho Júnior, A. B.; Maia, A. F.

    2014-02-01

    The objective of this study was to characterise an anthropomorphic chest phantom for dosimetric measurements of conventional radiology beams. This phantom was developed by a previous research project at the Federal University of Sergipe for image quality control tests. As the phantom consists of tissue-equivalent material, it is possible to characterise it for dosimetric studies. For comparison, a geometric chest phantom, consisting of PMMA (polymethylmethacrylate) with dimensions of 30×30×15 cm³ was used. Measurements of incident air kerma (Ki) and entrance surface dose (ESD) were performed using ionisation chambers. From the results, backscatter factors (BSFs) of the two phantoms were determined and compared with values estimated by CALDose_X software, based on a Monte Carlo simulation. For the technical parameters evaluated in this study, the ESD and BSF values obtained experimentally showed a good similarity between the two phantoms, with minimum and maximum difference of 0.2% and 7.0%, respectively, and showed good agreement with the results published in the literature. Organ doses and effective doses for the anthropomorphic phantom were also estimated by the determination of conversion coefficients (CCs) using the visual Monte Carlo (VMC) code. Therefore, the results of this study prove that the anthropomorphic thorax phantom proposed is a good tool to use in dosimetry and can be used for risk evaluation of X-ray diagnostic procedures.

  18. Pre-evaluation study in SPECT images using a phantom

    International Nuclear Information System (INIS)

    Rebelo, Marina de Sa; Furuie, Sergio Shiguemi; Abe, Rubens; Moura, Lincoln

    1996-01-01

    An alternative solution for the reconstruction of SPECT images using a Poisson Noise Model is presented. The proposed algorithm was applied on a real phantom and compared to the standard clinical procedures. Results have shown that the proposed method improves the quality of the SPECT images

  19. Results of high heat flux tests and structural analysis of the new solid tungsten divertor tile for ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Jaksic, Nikola, E-mail: nikola.jaksic@ipp.mpg.de; Greuner, Henri; Herrmann, Albrecht; Böswirth, Bernd; Vorbrugg, Stefan

    2015-10-15

    Highlights: • The main motivation for the HHF investigation of tungsten tiles was an untypical deformation of some specimens under thermal loading, observed during the previous tests in GLADIS test facility. • A nonlinear finite element (FE) model for simulations of the GLADIS tests has been built. • The unexpected plastic deformations are mainly caused by internal stresses due to the manufacturing process. The small discrepancies among the FEA investigated and measured plastic deformations are most likely caused, beside of the practical difficulties by measuring of low items, also by tile internal stresses. • The influences of the residual stresses caused by special production processes have to be taken into account by design of the structural part made of solid tungsten. - Abstract: Tungsten as plasma-facing material for fusion devices is currently the most favorable candidate. In general solid tungsten is used for shielding the plasma chamber interior against the high heat generated from the plasma. For the purposes of implementation at ASDEX Upgrade and as a contribution to ITER the thermal performance of tungsten tiles has been extensively tested in the high heat flux test facility GLADIS during the development phase and beyond. These tests have been performed on full scale tungsten tile prototypes including their clamping and cooling structure. Simulating the adiabatically thermal loading due to plasma operation in ASDEX Upgrade, the tungsten tiles have been subjected to a thermal load with central heat flux of 10–24 MW/m{sup 2} and absorbed energy between 370 and 680 kJ. This loading results in maximum surface temperatures between 1300 °C and 2800 °C. The tests in GLADIS have been accompanied by intensive numerical investigations using FEA methods. For this purpose a multiple nonlinear finite element model has been set up. This paper discusses the main results of the high heat flux final tests and their numerical simulation. Moreover, first

  20. Results of high heat flux tests and structural analysis of the new solid tungsten divertor tile for ASDEX Upgrade

    International Nuclear Information System (INIS)

    Jaksic, Nikola; Greuner, Henri; Herrmann, Albrecht; Böswirth, Bernd; Vorbrugg, Stefan

    2015-01-01

    Highlights: • The main motivation for the HHF investigation of tungsten tiles was an untypical deformation of some specimens under thermal loading, observed during the previous tests in GLADIS test facility. • A nonlinear finite element (FE) model for simulations of the GLADIS tests has been built. • The unexpected plastic deformations are mainly caused by internal stresses due to the manufacturing process. The small discrepancies among the FEA investigated and measured plastic deformations are most likely caused, beside of the practical difficulties by measuring of low items, also by tile internal stresses. • The influences of the residual stresses caused by special production processes have to be taken into account by design of the structural part made of solid tungsten. - Abstract: Tungsten as plasma-facing material for fusion devices is currently the most favorable candidate. In general solid tungsten is used for shielding the plasma chamber interior against the high heat generated from the plasma. For the purposes of implementation at ASDEX Upgrade and as a contribution to ITER the thermal performance of tungsten tiles has been extensively tested in the high heat flux test facility GLADIS during the development phase and beyond. These tests have been performed on full scale tungsten tile prototypes including their clamping and cooling structure. Simulating the adiabatically thermal loading due to plasma operation in ASDEX Upgrade, the tungsten tiles have been subjected to a thermal load with central heat flux of 10–24 MW/m"2 and absorbed energy between 370 and 680 kJ. This loading results in maximum surface temperatures between 1300 °C and 2800 °C. The tests in GLADIS have been accompanied by intensive numerical investigations using FEA methods. For this purpose a multiple nonlinear finite element model has been set up. This paper discusses the main results of the high heat flux final tests and their numerical simulation. Moreover, first results

  1. Enceladus' 101 Geysers: Phantoms? Hardly

    Science.gov (United States)

    Porco, C.; Nimmo, F.; DiNino, D.

    2015-12-01

    The discovery by the Cassini mission of present-day geysering activity capping the southern hemisphere of Saturn's moon Enceladus (eg, Porco, C. C. et al. Science 311, 1393, 2006) and sourced within a subsurface body of liquid water (eg, Postberg, F. et al. Nature 459, 1098, 2009; Porco, C.C. et al. AJ 148, 45, 2014, hereafter PEA], laced with organic compounds (eg, Waite, J.H. et al. Science 311, 1419, 2006), has been a significant one, with far-reaching astrobiological implications. In an extensive Cassini imaging survey of the moon's south polar terrain (SPT), PEA identified 101 distinct, narrow jets of small icy particles erupting, with varying strengths, from the four major fractures crossing the SPT. A sufficient spread in stereo angles of the 107 images used in that work allowed (in some cases, many) pair-wise triangulations to be computed; precise surface locations were derived for 98 jets. Recently, it has been claimed (Spitale, J.N. et al. Nature 521, 57, 2015) that the majority of the geysers are not true discrete jets, but are "phantoms" that appear in shallow-angle views of a dense continuous curtain of material with acute bends in it. These authors also concluded that the majority of the eruptive material is not in the form of jets but in the form of fissure-style 'curtain' eruptions. We argue below the contrary, that because almost all the moon's geysers were identified by PEA using multiple images with favorable viewing geometries, the vast majority of them, and likely all, are discrete jets. Specifically, out of 98 jets, no fewer than 90 to 95 were identified with viewing geometries that preclude the appearance of phantoms. How the erupting solids (i.e., icy particles) that are seen in Cassini images are partitioned between jets and inter-jet curtains is still an open question.

  2. Monitoring results and analysis of thermal comfort conditions in experimental buildings for different heating systems and ventilation regimes during heating and cooling seasons

    Science.gov (United States)

    Gendelis, S.; Jakovičs, A.; Ratnieks, J.; Bandeniece, L.

    2017-10-01

    This paper focuses on the long-term monitoring of thermal comfort and discomfort parameters in five small test buildings equipped with different heating and cooling systems. Calculations of predicted percentage of dissatisfied people (PPD) index and discomfort factors are provided for the room in winter season running three different heating systems - electric heater, air-air heat pump and air-water heat pump, as well as for the summer cooling with split type air conditioning systems. It is shown that the type of heating/cooling system and its working regime has an important impact on thermal comfort conditions in observed room. Recommendations for the optimal operating regimes and choice of the heating system from the thermal comfort point of view are summarized.

  3. 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

  4. Dosimetric characteristics of water equivalent for two solid water phantoms

    International Nuclear Information System (INIS)

    Wang Jianhua; Wang Xun; Ren Jiangping

    2011-01-01

    Objective: To investigate the water equivalent of two solid water phantoms. Methods: The X-ray and electron beam depth-ion curves were measured in water and two solid water phantoms, RW3 and Virtual Water. The water-equivalency correction factors for the two solid water phantoms were compared. We measured and calculated the range sealing factors and the fluence correction factors for the two solid water phantoms in the case of electron beams. Results: The average difference between the measured ionization in solid water phantoms and water was 0.42% and 0.16% on 6 MV X-ray (t=-6.15, P=0.001 and t=-1.65, P=0.419) and 0.21% and 0.31% on 10 MV X-ray (t=1.728, P=0.135 and t=-2.296, P=0.061), with 17.4% and 14.5% on 6 MeV electron beams (t=-1.37, P=0.208 and t=-1.47, P=0.179) and 7.0% and 6.0% on 15 MeV electron beams (t=-0.58, P=0.581 and t=-0.90, P=0.395). The water-equivalency correction factors for the two solid water phantoms varied slightly largely, F=58.54, P=0.000 on 6 MV X-ray, F=0.211, P=0.662 on 10 MV X-ray, F=0.97, P=0.353 on 6 MeV electron beams, F=0.14, P=0.717 on 15 MeV electron beams. However, they were almost equal to 1 near the reference depths. The two solid water phantoms showed a similar tread of C pl increasing (F=26.40, P=0.014) and h pl decreasing (F=7.45, P=0.072) with increasing energy. Conclusion: The solid water phantom should undergo a quality control test before being clinical use. (authors)

  5. 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

  6. A phantom for quality control in mammography

    International Nuclear Information System (INIS)

    Gambaccini, M.; Rimondi, O.; Marziani, M.; Toti, A.

    1989-01-01

    A phantom for evaluating image quality in mammography has been designed and will be used in the Italian national programme ''Dose and Quality in Mammography''. The characteristics of the phantom are (a) about the same X-ray transmission as a 5 cm 50% fat and 50% water breast for energies between 15 and 50 keV and (b) optimum energies for imaging of the test objects (included in the phantom) in very close agreement with the optimum energies for imaging of calcifications and tumours in a 5 cm 50% fat and 50% water breast. An experimental comparison between the prototype and some commercial phantoms was carried out. Measurements are in progress to test the phantom's ability to evaluate the performances of mammographic systems quantitatively. (author)

  7. Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Williams, Cameron H.; Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2013-04-15

    Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest-abdomen-pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient 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. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve

  8. Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

    International Nuclear Information System (INIS)

    Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E.; Williams, Cameron H.; Frush, D.; Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

    2013-01-01

    Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest–abdomen–pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient 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. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore

  9. High field Q slope and the baking effect: Review of recent experimental results and new data on Nb heat treatments

    Directory of Open Access Journals (Sweden)

    G. Ciovati

    2010-02-01

    Full Text Available The performance of superconducting radio-frequency (SRF cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT is characterized by exponentially increasing rf losses (high-field Q slope, in the absence of field emission, which are often mitigated by low-temperature (100–140°C, 12–48 h baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q slope will be presented for cavities that had been heat treated in a vacuum furnace at high temperature without subsequent chemical etching. These studies are aimed at understanding the role of hydrogen on the high-field Q slope and at the passivation of the Nb surface during heat treatment. Improvement of the cavity performances, particularly of the cavities’ quality factor, have been obtained following the high-temperature heat treatments, while secondary ion mass spectroscopy surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.

  10. Optimization of phantom backscatter thickness and lateral scatter volume for radiographic film dosimetry

    International Nuclear Information System (INIS)

    Srivastava, R.P.; De Wagter, C.

    2012-01-01

    The aim of this study is to determine the optimal backscatter thickness and lateral phantom dimension beyond the irradiated volume for the dosimetric verification with radiographic film when applying large field sizes. Polystyrene and Virtual Water™ phantoms were used to study the influence of the phantom backscatter thickness. EDR2 and XV films were used in 6 and 18 MV photon beams. The results show 11.4% and 6.4% over-response of the XV2 film when compared to the ion chamber for 6 MV 30×30 and 10×10 cm 2 field sizes, respectively, when the phantom backscatter thickness is 5 cm. For the same setup, measurements with EDR2 films indicate 8.5% and 1.7% over-response. The XV2 film response in the polystyrene phantom is about 2.0% higher than in the Virtual Water™ phantom for the 6 MV beam and 20 cm backscatter thickness. Similar results were obtained for EDR2 film. In the lateral scatter study, film response was nearly constant within 5 cm of lateral thickness and it increases when lateral thickness increases due to more multiple scatter of low energy photons. The backscatter thickness of the phantom should be kept below 7 cm for the accuracy of the film dosimetry. The lateral extension of the phantom should not be more than 5 cm from the field boundary in case of large irradiated volumes.

  11. Comparison of methods for individualized astronaut organ dosimetry: Morphometry-based phantom library versus body contour autoscaling of a reference phantom

    Science.gov (United States)

    Sands, Michelle M.; Borrego, David; Maynard, Matthew R.; Bahadori, Amir A.; Bolch, Wesley E.

    2017-11-01

    One of the hazards faced by space crew members in low-Earth orbit or in deep space is exposure to ionizing radiation. It has been shown previously that while differences in organ-specific and whole-body risk estimates due to body size variations are small for highly-penetrating galactic cosmic rays, large differences in these quantities can result from exposure to shorter-range trapped proton or solar particle event radiations. For this reason, it is desirable to use morphometrically accurate computational phantoms representing each astronaut for a risk analysis, especially in the case of a solar particle event. An algorithm was developed to automatically sculpt and scale the UF adult male and adult female hybrid reference phantom to the individual outer body contour of a given astronaut. This process begins with the creation of a laser-measured polygon mesh model of the astronaut's body contour. Using the auto-scaling program and selecting several anatomical landmarks, the UF adult male or female phantom is adjusted to match the laser-measured outer body contour of the astronaut. A dosimetry comparison study was conducted to compare the organ dose accuracy of both the autoscaled phantom and that based upon a height-weight matched phantom from the UF/NCI Computational Phantom Library. Monte Carlo methods were used to simulate the environment of the August 1972 and February 1956 solar particle events. Using a series of individual-specific voxel phantoms as a local benchmark standard, autoscaled phantom organ dose estimates were shown to provide a 1% and 10% improvement in organ dose accuracy for a population of females and males, respectively, as compared to organ doses derived from height-weight matched phantoms from the UF/NCI Computational Phantom Library. In addition, this slight improvement in organ dose accuracy from the autoscaled phantoms is accompanied by reduced computer storage requirements and a more rapid method for individualized phantom generation

  12. Cosmological perturbations on the phantom brane

    Energy Technology Data Exchange (ETDEWEB)

    Bag, Satadru; Sahni, Varun [Inter-University Centre for Astronomy and Astrophysics, Pune (India); Viznyuk, Alexander; Shtanov, Yuri, E-mail: satadru@iucaa.in, E-mail: viznyuk@bitp.kiev.ua, E-mail: shtanov@bitp.kiev.ua, E-mail: varun@iucaa.in [Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine)

    2016-07-01

    We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, w {sub eff} < −1, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom—the 'Weyl fluid' or 'dark radiation'. Setting initial conditions on super-Hubble spatial scales at the epoch of radiation domination, we evolve perturbations of radiation, pressureless matter and the Weyl fluid until the present epoch. We observe a gradual decrease in the amplitude of the Weyl-fluid perturbations after Hubble-radius crossing, which results in a negligible effect of the Weyl fluid on the evolution of matter perturbations on spatial scales relevant for structure formation. Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials Φ and Ψ evolve differently on the brane than in ΛCDM, for which Φ = Ψ. On the brane, by contrast, the ratio Φ/Ψ exceeds unity during the late matter-dominated epoch ( z ∼< 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large-scale structure.

  13. Phantom motor execution facilitated by machine learning and augmented reality as treatment for phantom limb pain: a single group, clinical trial in patients with chronic intractable phantom limb pain.

    Science.gov (United States)

    Ortiz-Catalan, Max; Guðmundsdóttir, Rannveig A; Kristoffersen, Morten B; Zepeda-Echavarria, Alejandra; Caine-Winterberger, Kerstin; Kulbacka-Ortiz, Katarzyna; Widehammar, Cathrine; Eriksson, Karin; Stockselius, Anita; Ragnö, Christina; Pihlar, Zdenka; Burger, Helena; Hermansson, Liselotte

    2016-12-10

    Phantom limb pain is a debilitating condition for which no effective treatment has been found. We hypothesised that re-engagement of central and peripheral circuitry involved in motor execution could reduce phantom limb pain via competitive plasticity and reversal of cortical reorganisation. Patients with upper limb amputation and known chronic intractable phantom limb pain were recruited at three clinics in Sweden and one in Slovenia. Patients received 12 sessions of phantom motor execution using machine learning, augmented and virtual reality, and serious gaming. Changes in intensity, frequency, duration, quality, and intrusion of phantom limb pain were assessed by the use of the numeric rating scale, the pain rating index, the weighted pain distribution scale, and a study-specific frequency scale before each session and at follow-up interviews 1, 3, and 6 months after the last session. Changes in medication and prostheses were also monitored. Results are reported using descriptive statistics and analysed by non-parametric tests. The trial is registered at ClinicalTrials.gov, number NCT02281539. Between Sept 15, 2014, and April 10, 2015, 14 patients with intractable chronic phantom limb pain, for whom conventional treatments failed, were enrolled. After 12 sessions, patients showed statistically and clinically significant improvements in all metrics of phantom limb pain. Phantom limb pain decreased from pre-treatment to the last treatment session by 47% (SD 39; absolute mean change 1·0 [0·8]; p=0·001) for weighted pain distribution, 32% (38; absolute mean change 1·6 [1·8]; p=0·007) for the numeric rating scale, and 51% (33; absolute mean change 9·6 [8·1]; p=0·0001) for the pain rating index. The numeric rating scale score for intrusion of phantom limb pain in activities of daily living and sleep was reduced by 43% (SD 37; absolute mean change 2·4 [2·3]; p=0·004) and 61% (39; absolute mean change 2·3 [1·8]; p=0·001), respectively. Two of four

  14. Research results from a prototype for power generation from low temperature heat sources in small and medium sized sawmills

    Energy Technology Data Exchange (ETDEWEB)

    Tveit, Tor-Martin; Hoeeg, Arne; Asphjell, Trond-Atle; Horn, Henning

    2010-07-01

    In this paper we present research results from a low temperature power generation unit prototype, SPP 2-67A, installed at the timber company Moelven Eidsvold Vaerk in Norway. The power generation unit is a Stirling cycle reciprocating engine connected to a generator, which is designed to combine the mature technology for high temperature Stirling engines (as seen for instance as air independent propulsion (AIP) units in submarines) and recent academic work on low temperature Stirling engines. The power generation unit is installed in a boiler room at the Moelven Eidsvold Vaerk plant and uses steam at approximately 1.5 bar pressure as a heat source. The steam is generated in the 5.5 MW biomass-fuelled boiler, where bark of Norway spruce (Picea abies) is the main biofuel. The installation has been intended both to use hot water as a heat sink to demonstrate CHP operation, and cold water from the grid to demonstrate maximum power generation from surplus steam. The installation is part of a research project partly financed by the Research Council of Norway, with the goal of testing new technology to improve the use of bioenergy resources and conversion of heat from biofuels to power. (Author)

  15. Heat Transfer and Flow on the First Stage Blade Tip of a Power Generation Gas Turbine. Part 1; Experimental Results

    Science.gov (United States)

    Bunker, Ronald S.; Bailey, Jeremy C.; Ameri, Ali A.

    1999-01-01

    A combined computational and experimental study has been performed to investigate the detailed distribution of convective heat transfer coefficients on the first stage blade tip surface for a geometry typical of large power generation turbines(>100MW). This paper is concerned with the design and execution of the experimental portion of the study. A stationary blade cascade experiment has been run consisting of three airfoils, the center airfoil having a variable tip gap clearance. The airfoil models the aerodynamic tip section of a high pressure turbine blade with inlet Mach number of 0.30, exit Mach number of 0.75, pressure ratio of 1.45, exit Reynolds number based on axial chord of 2.57 x 10(exp 6), and total turning of about 110 degrees. A hue detection based liquid crystal method is used to obtain the detailed heat transfer coefficient distribution on the blade tip surface for flat, smooth tip surfaces with both sharp and rounded edges. The cascade inlet turbulence intensity level took on values of either 5% or 9%. The cascade also models the casing recess in the shroud surface ahead of the blade. Experimental results are shown for the pressure distribution measurements on the airfoil near the tip gap, on the blade tip surface, and on the opposite shroud surface. Tip surface heat transfer coefficient distributions are shown for sharp-edge and rounded-edge tip geometries at each of the inlet turbulence intensity levels.

  16. Tracked ultrasound calibration studies with a phantom made of LEGO bricks

    Science.gov (United States)

    Soehl, Marie; Walsh, Ryan; Rankin, Adam; Lasso, Andras; Fichtinger, Gabor

    2014-03-01

    In this study, spatial calibration of tracked ultrasound was compared by using a calibration phantom made of LEGO® bricks and two 3-D printed N-wire phantoms. METHODS: The accuracy and variance of calibrations were compared under a variety of operating conditions. Twenty trials were performed using an electromagnetic tracking device with a linear probe and three trials were performed using varied probes, varied tracking devices and the three aforementioned phantoms. The accuracy and variance of spatial calibrations found through the standard deviation and error of the 3-D image reprojection were used to compare the calibrations produced from the phantoms. RESULTS: This study found no significant difference between the measured variables of the calibrations. The average standard deviation of multiple 3-D image reprojections with the highest performing printed phantom and those from the phantom made of LEGO® bricks differed by 0.05 mm and the error of the reprojections differed by 0.13 mm. CONCLUSION: Given that the phantom made of LEGO® bricks is significantly less expensive, more readily available, and more easily modified than precision-machined N-wire phantoms, it prompts to be a viable calibration tool especially for quick laboratory research and proof of concept implementations of tracked ultrasound navigation.

  17. The design and fabrication of two portal vein flow phantoms by different methods

    Energy Technology Data Exchange (ETDEWEB)

    Yunker, Bryan E., E-mail: bryan.yunker@ucdenver.edu; Lanning, Craig J.; Shandas, Robin; Hunter, Kendall S. [Department of Bioengineering, University of Colorado – Denver/Anschutz, 12700 East 19th Avenue, MS 8607, Aurora, Colorado 80045 (United States); Dodd, Gerald D., E-mail: gerald.dodd@ucdenver.edu; Chang, Samuel; Scherzinger, Ann L. [Department of Radiology, University of Colorado – SOM, 12401 East 17th Avenue, Mail Stop L954, Aurora, Colorado 80045 (United States); Chen, S. James, E-mail: james.chen@ucdenver.edu [Department of Medicine, University of Colorado Denver, Colorado 80045 and Department of Medicine/Cardiology, University of Colorado – SOM, 12401 East 17th Avenue, Mail Stop B132, Aurora, Colorado 80045 (United States); Feng, Yusheng, E-mail: yusheng.feng@utsa.edu [Department of Mechanical Engineering, University of Texas – San Antonio, One UTSA Circle, Mail Stop: AET 2.332, San Antonio, Texas 78249–0670 (United States)

    2014-02-15

    Purpose: This study outlines the design and fabrication techniques for two portal vein flow phantoms. Methods: A materials study was performed as a precursor to this phantom fabrication effort and the desired material properties are restated for continuity. A three-dimensional portal vein pattern was created from the Visual Human database. The portal vein pattern was used to fabricate two flow phantoms by different methods with identical interior surface geometry using computer aided design software tools and rapid prototyping techniques. One portal flow phantom was fabricated within a solid block of clear silicone for use on a table with Ultrasound or within medical imaging systems such as MRI, CT, PET, or SPECT. The other portal flow phantom was fabricated as a thin walled tubular latex structure for use in water tanks with Ultrasound imaging. Both phantoms were evaluated for usability and durability. Results: Both phantoms were fabricated successfully and passed durability criteria for flow testing in the next project phase. Conclusions: The fabrication methods and materials employed for the study yielded durable portal vein phantoms.

  18. Test results on prototype 50-kA conductors for tokamak induction heating coils

    International Nuclear Information System (INIS)

    Wollan, J.J.; Williamson, K.D. Jr.; Turck, B.

    1979-01-01

    Fabricability of a very large, 50-kA superconducting cable has been demonstrated. Test results of critical current and stability measurements are presented. The design critical current of 55 kA at 7 T was met. The recovery current was degraded as a result of the expectedly poor insulation system. Energy loss measurements on prototype advanced mixed matrix conductors, which will be incorporated into a second prototype cable, are presented

  19. Distributions of neutron and gamma doses in phantom under a mixed field

    International Nuclear Information System (INIS)

    Beraud-Sudreau, E.

    1982-06-01

    A calculation program, based on Monte Carlo method, allowed to estimate the absorbed doses relatives to the reactor primary radiation, in a water cubic phantom and in cylindrical phantoms modelized from tissue compositions. This calculation is a theoretical approach of gamma and neutron dose gradient study in an animal phantom. PIN junction dosimetric characteristics have been studied experimentally. Air and water phantom radiation doses measured by PIN junction and lithium 7 fluoride, in reactor field have been compared to doses given by dosimetry classical techniques as tissue equivalent plastic and aluminium ionization chambers. Dosimeter responses have been employed to evaluate neutron and gamma doses in plastinaut (tissue equivalent plastic) and animal (piglet). Dose repartition in the piglet bone medulla has been also determined. This work has been completed by comparisons with Doerschell, Dousset and Brown results and by neutron dose calculations; the dose distribution related to lineic energy transfer in Auxier phantom has been also calculated [fr

  20. Using NURBS type phantoms for the investigation of morphological factors affecting pulmonary anthropo-radiometry

    International Nuclear Information System (INIS)

    Farah, J.; Broggio, D.; Franck, D.

    2010-01-01

    As existing phantoms used for the calibration of dosimetry measurements, notably in anthropo-radiometry, exhibit a poor anatomic realism because of their crude geometries, compositions and densities, and some other drawbacks, the authors, within the frame of improvement of calibration techniques, report the combined use of Mesh and NURBS-type phantoms (Non Uniform Rational B-Splines) which allow smooth shapes and finer geometries to be replicated. More precisely, they report the application of this type of phantoms to the modelling of a thorax and of a ribcage. They describe the protocols used to generate these phantoms and how some variations are introduced to take morphological characteristics (for example a female thorax) as well as various gamma ray distributions into account. Results are discussed in terms of validation of phantoms, and morphology variation

  1. Spherical phantom for research of radiation situation in outer space. Design-structural special features

    International Nuclear Information System (INIS)

    Kartsev, I.S.; Eremenko, V.G.; Petrov, V.I.; Polenov, B.V.; Yudin, V.N.; Akatov, Yu.A.; Petrov, V.M.; Shurshakov, V.A.

    2005-01-01

    The design-structural features of the updated spherical phantom applied within the frameworks of the space experiment Matreshka-R at the Russian segment of International space station during ISS-8 and ISS-9 expeditions are described. The replacement of 48 polyethylene containers with TLD and STD assemblies by 16 cases installed from external side of the phantom and 4 tissue-equivalent caps of the central disk by 4 cases with detector assemblies is carried out. The updated tissue-equivalent phantom contains the active dosemeter based on 5 MOS detectors. The phantom cover is made from the non-flammable material NT-7. The basic characteristics of the flight specimen of the phantom are presented. The results of its on-Earth testing and real space flights are analyzed [ru

  2. Phantom sensations in people with complete spinal cord lesions: a grounded theory perspective.

    Science.gov (United States)

    Drysdale, Daren G; Shem, Kazuko; Walbom, Agnes; Miner, Maureen D; Maclachlan, Malcolm

    2009-01-01

    Phantom sensations are somatic phenomena arising from denervated parts of the body. There is very little research, and much diagnostic confusion, regarding such experiences in people with spinal cord injuries. In the case of 'complete' spinal cord lesions, phantom experiences may challenge, and indeed, contradict, the understanding that both clinicians and patients have of such injuries. This paper seeks to provide a better understanding of such 'phantom' sensations in spinal cord injury. We used grounded theory methods to explore 'phantom' sensations as experienced by individuals with complete (ASIA A) spinal lesions. Eight people with complete lesions, who were selected through theoretical sampling, participated in a semi-structured interview. Emergent themes included injury context, sensations experienced, the meaning of sensations, body connectivity, attitude and communication about sensations. Our results provide an enhanced understanding of the embodied experience of phantom sensations, and important insights regarding self-construction and rehabilitative processes in people with spinal cord injury who experience such anomalous sensations.

  3. Near infrared spatial frequency domain fluorescence imaging of tumor phantoms containing erythrocyte-derived optical nanoplatforms

    Science.gov (United States)

    Burns, Joshua M.; Schaefer, Elise; Anvari, Bahman

    2018-02-01

    Light-activated theranostic constructs provide a multi-functional platform for optical imaging and phototherapeutic applications. Our group has engineered nano-sized vesicles derived from erythrocytes that encapsulate the FDAapproved near infrared (NIR) absorber indocyanine green (ICG). We refer to these constructs as NIR erythrocytemimicking transducers (NETs). Once photo-excited by NIR light these constructs can transduce the photons energy to emit fluorescence, generate heat, or induce chemical reactions. In this study, we investigated fluorescence imaging of NETs embedded within tumor phantoms using spatial frequency domain imaging (SFDI). Using SFDI, we were able to fluorescently image simulated tumors doped with different concentration of NETs. These preliminary results suggest that NETs can be used in conjunction with SFDI for potential tumor imaging applications.

  4. 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)

  5. Neutron measurements with a tissue-equivalent phantom

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J W [Health Physics Division, Atomic Energy Establishment, Harwell (United Kingdom)

    1962-03-15

    This Appendix 3E of the dosimetry experiment at the R-B reactor describes the apparatus used and presents the obtained results. The phantom used was a 1/4-inch thick polythene container, 60 cm high, of elliptical cross-section, with a major axis of 36 cm and a minor axis of 20 cm. This was filled with an approximately tissue-equivalent liquid. A light but rigid internal framework of Perspex supported a series of small detectors through the phantom. The detectors used in the first high-level run at Vinca, to measure flux above 0.5 MeV, were 0.5-cm wide track plates wrapped in cadmium foil. Each track plate was a sandwich of two Ilford El 50 - mu emulsions, with glass backing, separated by a 250-mu polythene radiator, and was oriented at an angle of 45 deg to the front surface of the phantom. Under these conditions the response is constant with neutron energy between 0.5 MeV and 8 MeV at 1.26 X 10 sup - sup 3 tracks/neutron to within +- 15%. The detectors used in the second high-level run were gold foils (260 mg/cm sup 2 thick) for determination of the show neutron distribution. Previous experiments with 0.13 MeV, 2.5 MeV, 14 MeV and Po-Be neutrons have shown that the shape of the curve through a phantom obtained from these gold foils is the same as that given by either manganese foils or sodium samples despite the difference in resonance integrals. From the relaxation length of the neutron flux in the phantom, as measured by the track plates, the mean energy of the neutrons with energies greater than 0.5 MeV may be found by comparison with the relaxation lengths obtained by irradiation of the phantom with monoenergetic neutrons. The results of these experiments are given. Track plate results from the Vinca experiment are shown. It can be seen that the backscattered fast flux is about one-third of the incident fast flux and that the energy indicated by the shape of the curve is considerably lower than the energy of the direct neutrons. It seems possible that the high

  6. Neutron measurements with a tissue-equivalent phantom

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J W [Health Physics Division, Atomic Energy Establishment, Harwell (United Kingdom)

    1962-03-01

    This Appendix 3E of the dosimetry experiment at the R-B reactor describes the apparatus used and presents the obtained results. The phantom used was a 1/4-inch thick polythene container, 60 cm high, of elliptical cross-section, with a major axis of 36 cm and a minor axis of 20 cm. This was filled with an approximately tissue-equivalent liquid. A light but rigid internal framework of Perspex supported a series of small detectors through the phantom. The detectors used in the first high-level run at Vinca, to measure flux above 0.5 MeV, were 0.5-cm wide track plates wrapped in cadmium foil. Each track plate was a sandwich of two Ilford El 50 - {mu} emulsions, with glass backing, separated by a 250-{mu} polythene radiator, and was oriented at an angle of 45 deg to the front surface of the phantom. Under these conditions the response is constant with neutron energy between 0.5 MeV and 8 MeV at 1.26 X 10{sup -3} tracks/neutron to within {+-} 15%. The detectors used in the second high-level run were gold foils (260 mg/cm{sup 2} thick) for determination of the show neutron distribution. Previous experiments with 0.13 MeV, 2.5 MeV, 14 MeV and Po-Be neutrons have shown that the shape of the curve through a phantom obtained from these gold foils is the same as that given by either manganese foils or sodium samples despite the difference in resonance integrals. From the relaxation length of the neutron flux in the phantom, as measured by the track plates, the mean energy of the neutrons with energies greater than 0.5 MeV may be found by comparison with the relaxation lengths obtained by irradiation of the phantom with monoenergetic neutrons. The results of these experiments are given. Track plate results from the Vinca experiment are shown. It can be seen that the backscattered fast flux is about one-third of the incident fast flux and that the energy indicated by the shape of the curve is considerably lower than the energy of the direct neutrons. It seems possible that the

  7. Development of digital phantom for DRR evaluation

    International Nuclear Information System (INIS)

    Ikeda, Tsuyoshi; Katsuta, Shoichi; Oyama, Masaya; Ogino, Takashi

    2009-01-01

    Generally, digitally reconstructed radiograph (DRR) is evaluated by physical phantom. The CT image is camouflaged by the performance of the radiation treatment planning system and contains a variety of error factors. The CT image (as follows the digital phantom), where an arbitrary CT value is arranged in the matrix, is necessary to evaluate the pure performance of the radiation treatment planning system. In this study, the development of a digital phantom is described, and the utility is discussed. CTport and the radiation treatment planning system are evaluated with the use of a digital phantom as follows: geometrical accuracy evaluation of DRR, consisting of the center position, size of irradiation field, distortion, extension of X-ray, and beam axis, and the image quality evaluation of DRR, which consists of the contrast resolution. As for DRR made with CTport and the treatment planning system, the part that shifted geometrically was confirmed. In the image quality evaluation, there was a remarkable difference. Because the making accuracy and the installation accuracy of the phantom do not influence the digital phantom, the geometrical accuracy of the DRR is reliable. Because the CT conditions and the phantom factor have no influence, the peculiar DRR image quality can be evaluated and used to evaluate the best image processing parameters. (author)

  8. Evaluation of tomosynthesis elastography in a breast-mimicking phantom

    International Nuclear Information System (INIS)

    Engelken, Florian Jan; Sack, Ingolf; Klatt, Dieter; Fischer, Thomas; Fallenberg, Eva Maria; Bick, Ulrich; Diekmann, Felix

    2012-01-01

    Objective: To evaluate whether measurement of strain under static compression in tomosynthesis of a breast-mimicking phantom can be used to distinguish tumor-simulating lesions of different elasticities and to compare the results to values predicted by rheometric analysis as well as results of ultrasound elastography. Materials and methods: We prepared three soft breast-mimicking phantoms containing simulated tumors of different elasticities. The phantoms were imaged using a wide angle tomosynthesis system with increasing compression settings ranging from 0 N to 105 N in steps of 15 N. Strain of the inclusions was measured in two planes using a commercially available mammography workstation. The elasticity of the phantom matrix and inclusion material was determined by rheometric analysis. Ultrasound elastography of the inclusions was performed using two different ultrasound elastography algorithms. Results: Strain at maximal compression was 24.4%/24.5% in plane 1/plane 2, respectively, for the soft inclusion, 19.6%/16.9% for the intermediate inclusion, and 6.0%/10.2% for the firm inclusion. The strain ratios predicted by rheometrical testing were 0.41, 0.83 and 1.26 for the soft, intermediate, and firm inclusions, respectively. The strain ratios obtained for the soft, intermediate, and firm inclusions were 0.72 ± 0.13, 1.02 ± 0.21 and 2.67 ± 1.70, respectively for tomosynthesis elastography, 0.91, 1.64 and 2.07, respectively, for ultrasound tissue strain imaging, and 0.97, 2.06 and 2.37, respectively, for ultrasound real-time elastography. Conclusions: Differentiation of tumor-simulating inclusions by elasticity in a breast mimicking phantom may be possible by measuring strain in tomosynthesis. This method may be useful for assessing elasticity of breast lesions tomosynthesis of the breast

  9. Comparison between FEM and high heat flux thermal fatigue testing results of ITER divertor plasma facing mock-ups

    Energy Technology Data Exchange (ETDEWEB)

    Crescenzi, F., E-mail: fabio.crescenzi@enea.it; Roccella, S.; Visca, E.; Moriani, A.

    2014-10-15

    Highlights: • Divertor is an important part of the ITER machine. • Finite element analysis allows designers to explore multiple design options, reducing physical prototypes and optimizing design performance. • The hydraulic thermal-mechanical analysis performed by ANSYS and the test results on small-scale mock-ups manufactured by HRP were compared. • FEA results confirmed many experimental data, then it could be very useful for next design optimization. - Abstract: The divertor is one of the most challenging components of “DEMO” the next step ITER machine, so many tasks regarding modeling and experiments have been made in the past years to assess manufacturing processes, materials and thus the life-time of the components. In this context the finite element analysis (FEA) allows designers to explore multiple design options, to reduce physical prototypes and to optimize design performance. The comparison between the hydraulic thermal-mechanical analysis performed by ANSYS WORKBENCH 14.5 and the test results [1] on small-scale mock-ups manufactured with the Hot Radial Pressing (HRP) [2] technology is presented in this paper. During the thermal fatigue testing in the Efremov TSEFEY facility to assess the heat flux load-carrying capability of the mock-ups, only the surface temperature was measured, so the FEA was important because it allowed to know any other information (temperature inside the materials, local water temperature, local stress, etc.). FEA was performed coupling the thermal-hydraulic analysis, that calculated the temperature distributions on the components and the heat transfer coefficient (HTC) between water and heat sink tube, with the mechanical analysis. The comparison between analysis and testing results was based on the temperature maps of the loaded surface and on number of the cycles supported during the testing and those predicted by the mechanical analysis using the experimental fatigue curves for CuCrZr-IG, that is the structural

  10. Quality assessment of brain images by Hoffman phantom

    International Nuclear Information System (INIS)

    Karimian, A.R.; Saddad, F.; Mosalla, B.; Moradkhani, S.; Degbankhan, R.; Pouladi, M.

    2002-01-01

    The purpose of this investigation is using Hoffman brain phantom for quality assessment of brian images in SPECT system. There are the following standards for quality control in nuclear medicine: American Association of Physicists in Medicine, National Electrical Manufacturers Association, International Electromechanical Commission, International Atomic Energy Agency. Each of the above standards has the following important orders: Physical inspection, Acceptance and Reference Testing, Periodic Q C tests (Daily, Weekly, Monthly, Quarterly, Annually). The above tests are simple physics measures. To more meaningful ones based on performance of some tasks related to clinical application it is better to use from organs' phantoms, such as: brain, cardiac, etc. In this research we made a comparison between normal and abnormal states of Hoffman brain phantom. Methods of Hoffman brain phantom was filled with a solution of Tc- 99 m (5 mCi) and water (1300 cc). this results: The investigation of small abnormalities strongly related to the operating conditions and deviation from best tuning state of the system

  11. Gravitational Quasinormal Modes of Regular Phantom Black Hole

    Directory of Open Access Journals (Sweden)

    Jin Li

    2017-01-01

    Full Text Available We investigate the gravitational quasinormal modes (QNMs for a type of regular black hole (BH known as phantom BH, which is a static self-gravitating solution of a minimally coupled phantom scalar field with a potential. The studies are carried out for three different spacetimes: asymptotically flat, de Sitter (dS, and anti-de Sitter (AdS. In order to consider the standard odd parity and even parity of gravitational perturbations, the corresponding master equations are derived. The QNMs are discussed by evaluating the temporal evolution of the perturbation field which, in turn, provides direct information on the stability of BH spacetime. It is found that in asymptotically flat, dS, and AdS spacetimes the gravitational perturbations have similar characteristics for both odd and even parities. The decay rate of perturbation is strongly dependent on the scale parameter b, which measures the coupling strength between phantom scalar field and the gravity. Furthermore, through the analysis of Hawking radiation, it is shown that the thermodynamics of such regular phantom BH is also influenced by b. The obtained results might shed some light on the quantum interpretation of QNM perturbation.

  12. Are phantoms useful for predicting the potential of dose reduction in full-field digital mammography?

    International Nuclear Information System (INIS)

    Gennaro, Gisella; Katz, Luc; Souchay, Henri; Alberelli, Claudio; Maggio, Cosimo di

    2005-01-01

    A phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future clinical study on the impact of dose reduction on clinical results. Three different mammography phantoms (ACR RMI 156, CIRS 11A and CDMAM 3.4) were imaged by a full-field digital mammography unit (GE Senographe 2000D) at different dose levels. Images were rated by three observers with softcopy reading and scoring methods specific to each phantom. Different types of data analysis were applied to the ACR (American College of Radiology) and the other two phantoms, respectively. With reference to the minimum acceptance score in screen/film accreditation programmes, the ACR phantom showed that about 45% dose reduction could be applied, while keeping the phantom scores above that threshold. A relative comparison was done for CIRS and CDMAM, for which no threshold is defined. CIRS scoring remained close to the reference level down to 40% dose reduction, the inter- and intra-observer variability being the main source of uncertainty. Contrast-detail curves provided by CDMAM overlapped down to 50% dose reduction, at least for object contrast values ranging between 30% and 3%. This multi-phantom study shows the potential of further reducing the dose in full-field digital mammography beyond the current values. A common dose reduction factor around 50% seems acceptable for all phantoms. However, caution is required before extrapolating the results for clinical use, given the limitations of these widely used phantoms, mainly related to their limited dynamic range and uniform background

  13. Comparison of the results of several heat transfer computer codes when applied to a hypothetical nuclear waste repository

    International Nuclear Information System (INIS)

    Claiborne, H.C.; Wagner, R.S.; Just, R.A.

    1979-12-01

    A direct comparison of transient thermal calculations was made with the heat transfer codes HEATING5, THAC-SIP-3D, ADINAT, SINDA, TRUMP, and TRANCO for a hypothetical nuclear waste repository. With the exception of TRUMP and SINDA (actually closer to the earlier CINDA3G version), the other codes agreed to within +-5% for the temperature rises as a function of time. The TRUMP results agreed within +-5% up to about 50 years, where the maximum temperature occurs, and then began an oscillary behavior with up to 25% deviations at longer times. This could have resulted from time steps that were too large or from some unknown system problems. The available version of the SINDA code was not compatible with the IBM compiler without using an alternative method for handling a variable thermal conductivity. The results were about 40% low, but a reasonable agreement was obtained by assuming a uniform thermal conductivity; however, a programming error was later discovered in the alternative method. Some work is required on the IBM version to make it compatible with the system and still use the recommended method of handling variable thermal conductivity. TRANCO can only be run as a 2-D model, and TRUMP and CINDA apparently required longer running times and did not agree in the 2-D case; therefore, only HEATING5, THAC-SIP-3D, and ADINAT were used for the 3-D model calculations. The codes agreed within +-5%; at distances of about 1 ft from the waste canister edge, temperature rises were also close to that predicted by the 3-D model

  14. Measurements of parametric instability near the critical density and the resultant electron heating: Final report

    International Nuclear Information System (INIS)

    Mizuno, K.; De Groot, J.S.; Seka, W.

    1986-01-01

    Detailed studies of the ion acoustic parametric decay instability have been made. Theoretical and particle simulation results indicate these instabilities are important in long scale length plasma irradiated by moderate intensity laser light (10'' ≤ Iλ 2 /T/sub e/ (W/cm 2 ) (μm 2 )/(keV) ≤ 5 x 10 14 ). Laser light (λ 0 ≅ 1/2 μm) is focused onto a CH target. The parametric decay instability has been measured by detecting the emission spectrum at frequencies near 2ω 0 . The experimental results clearly indicate that this parametric instability is important for short wavelength (1/2 μm) laser light irradiation. The threshold of the parametric instability (λ 0 = 1/2 μm) was only slightly higher than that of 1 μm laser case. The measured wavelength shift of the Stokes component (λ 0 = 1/2 μm) compared very well with the 1 μm laser results

  15. 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.

  16. 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.

  17. Results and analysis of high heat flux tests on a full-scale vertical target prototype of ITER divertor

    International Nuclear Information System (INIS)

    Missirlian, M.; Escourbiac, F.; Merola, M.; Bobin-Vastra, I.; Schlosser, J.; Durocher, A.

    2005-01-01

    After an extensive R and D development program, a full-scale divertor target prototype, manufactured with all the main features of the corresponding ITER divertor, was intensively tested in the high heat flux FE200 facility. The prototype consists of four units having a full monoblock geometry. The lower part (CFC armour) and the upper part (W armour) of each monoblock were joined to the solution annealed, quenched and cold worked CuCrZr tube by HIP technique. This paper summarises and analyses the main test results obtained on this prototype

  18. Valve stem packing seal test results for primary heat transport system conditions in Canadian nuclear generating stations

    International Nuclear Information System (INIS)

    Dixon, D.F.; Farrell, J.M.; Coutinho, R.F.

    1978-06-01

    Valve stem packing tests were done to obtain performance data on packing already in CANDU-PHW reactor service and on alternative packings. Most of the tests were replicated. Results are presented for ten packings tested under two stem cycle modes; leakage, packing consolidation and packing friction were the main responses. Packing tests were performed with water at close to CANDU-PHW reactor primary heat transport (PHT) system conditions (288 deg C and 10 MPa), but without ionizing radiation. The test rigs had rising, rotating stems. Stuffing box dimensions were typical of a standard Velan valve; packings were spring loaded to control applied packing stress

  19. Charged black holes in phantom cosmology

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-15

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

  20. 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

  1. 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

  2. Wormholes supported by phantom energy

    International Nuclear Information System (INIS)

    Gonzalez, J. A.; Guzman, F. S.; Montelongo-Garcia, N.; Zannias, T.

    2009-01-01

    By a combination of analytical and numerical techniques, we demonstrate the existence of spherical, asymptotically flat traversable wormholes supported by exotic matter whose stress tensor relative to the orthonormal frame of Killing observers takes the form of a perfect fluid possessing anisotropic pressures and subject to linear equations of state: τ=λρc 2 , P=μρc 2 . We show that there exists a four parameter family of asymptotically flat spherical wormholes parametrized by the area of the throat A(0), the gradient Λ(0) of the red shift factor evaluated on the throat as well as the values of (λ,μ). The latter are subject to restrictions: λ>1 and 2μ>λ or λ<0 and 2μ<-|λ|. For particular values of (λ,μ), the stress tensor may be interpreted as representing a phantom configuration, while for other values represents exotic matter. All solutions have the property that the two asymptotically flat ends possess finite Arnowitt-Deser-Misner mass.

  3. Estimation of internal dose from radiocesium and phantom

    International Nuclear Information System (INIS)

    Uchiyama, Masafumi; Nakamura, Yuji

    1994-01-01

    A complicated model describing the movement of a radionuclide in both the natural environment and socioeconomical systems is usually used to estimate the internal dose to the public in terms of collective dose, taking demographic data into account. The result can be certified for reliability in some compartments of the model. One of the compartments is the body content. In the case of radiocesium, the individual body burden can be measured using a whole-body counter. The measurement must be calibrated with a phantom. The public is composed of individuals of various ages. Accordingly, the whole-body counter should be calibrated with a set of phantoms approximating individuals of different body sizes. Relationships between counting efficiency and body size were analyzed on 137 Cs 134 Cs or 40 K incorporated into the whole-body using a set of phantoms. Four sizes covering average Japanese physiques from infant to adult male, were chosen to prepare an anthropomorphic phantom system. The distribution of 137 Cs in aquatic solution was homogeneous through the phantom. A whole-body counter at the National Institute of Radiological Sciences, was used at a rate of 5 cm per minute in a scanning mode. The measurements were carried out in an iron room. Relations were analyzed between counting efficiency and some anthropometric parameters. The best fit was given by a linear equation of both reciprocals of height in cm and weight in kg, with a correlation coefficient of 1.00 for 137 Cs. The result indicates that radioactivity of 137 Cs can be determined for individuals with different anthropometric parameters using the whole-body counter system. This means that effective equivalent doses for individuals can be computed accurately from the measurements. Further, an estimate on the body content from an dose estimation model using measurements of radioactivity in environmental substances can be evaluated by comparing the body burden measured. (J.P.N.)

  4. Development of System for Evaluating Concrete Strength Deterioration Due to Radiation and Resultant Heat

    International Nuclear Information System (INIS)

    Maruyama, I.; Kontani, O.; Ishizawa, A.; Takizawa, M.; Sato, O.

    2012-01-01

    Evaluation of the soundness of concrete exposed to irradiation has been studied within the framework of a project of the Nuclear and Industrial Safety Agency (NISA) 'Japan Ageing Management Program for System Safety'. This contribution presents the background to the existing evaluation processes, a review of the irradiation exposure effect on concrete and needs for irradiation testing. Based on results of this study, working assumptions for the development of an evaluation system are derived, and an overall picture of a numerical model as well as a framework for evaluating concrete soundness under irradiated conditions are proposed. (author)

  5. Method of processing results of tests of heating surfaces of a steam generator on a digital computer

    Energy Technology Data Exchange (ETDEWEB)

    Glusker, B.N.

    1975-03-01

    At present, processing of information obtained by testing steam generators in high-capacity generating units is carried out manually. This takes a long time and does not always permit one to process all the information obtained, which impoverishes the results of experimental work. In addition, this kind of processing of experimental results is as a rule done after completion of a considerable part of the tests, and occasionally after completion of all the tests. In this case, it is impossible to conduct a better directed, corrected experiment, and this leads to duplication of experiments and to increasing the period of adjusting and exploratory work on industrial plants. An algorithm was developed for automated processing of the hydraulic and temperature conditions of the heating surfaces in steam generators on digital computers, which is a part of the general algorithm of processing of results of thermal tests of steam generators. It includes calculation of all characteristics determining the thermal and hydraulic conditions of the heating surfaces. The program of processing includes a subprogram: determination of the thermophysical and thermodynamic properties of the water and steam.

  6. Material-specific Conversion Factors for Different Solid Phantoms Used in the Dosimetry of Different Brachytherapy Sources

    Directory of Open Access Journals (Sweden)

    Sedigheh Sina

    2015-07-01

    Full Text Available Introduction Based on Task Group No. 43 (TG-43U1 recommendations, water phantom is proposed as a reference phantom for the dosimetry of brachytherapy sources. The experimental determination of TG-43 parameters is usually performed in water-equivalent solid phantoms. The purpose of this study was to determine the conversion factors for equalizing solid phantoms to water. Materials and Methods TG-43 parameters of low- and high-energy brachytherapy sources (i.e., Pd-103, I-125 and Cs-137 were obtained in different phantoms, using Monte Carlo simulations. The brachytherapy sources were simulated at the center of different phantoms including water, solid water, poly(methyl methacrylate, polystyrene and polyethylene. Dosimetric parameters such as dose rate constant, radial dose function and anisotropy function of each source were compared in different phantoms. Then, conversion factors were obtained to make phantom parameters equivalent to those of water. Results Polynomial coefficients of conversion factors were obtained for all sources to quantitatively compare g(r values in different phantom materials and the radial dose function in water. Conclusion Polynomial coefficients of conversion factors were obtained for all sources to quantitatively compare g(r values in different phantom materials and the radial dose function in water.

  7. Three-dimensional printer-generated patient-specific phantom for artificial in vivo dosimetry in radiotherapy quality assurance.

    Science.gov (United States)

    Kamomae, Takeshi; Shimizu, Hidetoshi; Nakaya, Takayoshi; Okudaira, Kuniyasu; Aoyama, Takahiro; Oguchi, Hiroshi; Komori, Masataka; Kawamura, Mariko; Ohtakara, Kazuhiro; Monzen, Hajime; Itoh, Yoshiyuki; Naganawa, Shinji

    2017-12-01

    Pretreatment intensity-modulated radiotherapy quality assurance is performed using simple rectangular or cylindrical phantoms; thus, the dosimetric errors caused by complex patient-specific anatomy are absent in the evaluation objects. In this study, we construct a system for generating patient-specific three-dimensional (3D)-printed phantoms for radiotherapy dosimetry. An anthropomorphic head phantom containing the bone and hollow of the paranasal sinus is scanned by computed tomography (CT). Based on surface rendering data, a patient-specific phantom is formed using a fused-deposition-modeling-based 3D printer, with a polylactic acid filament as the printing material. Radiophotoluminescence glass dosimeters can be inserted in the 3D-printed phantom. The phantom shape, CT value, and absorbed doses are compared between the actual and 3D-printed phantoms. The shape difference between the actual and printed phantoms is less than 1 mm except in the bottom surface region. The average CT value of the infill region in the 3D-printed phantom is -6 ± 18 Hounsfield units (HU) and that of the vertical shell region is 126 ± 18 HU. When the same plans were irradiated, the dose differences were generally less than 2%. These results demonstrate the feasibility of the 3D-printed phantom for artificial in vivo dosimetry in radiotherapy quality assurance. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  8. 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

  9. 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

  10. 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.

  11. SU-C-209-07: Phantoms for Digital Breast Tomosynthesis Imaging System Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, D; Liu, Y [Medical College of Wisconsin, Milwaukee, WI (United States)

    2016-06-15

    Purpose: Digital Breast Tomosynthesis (DBT) is gaining importance in breast imaging. There is a need for phantoms that can be used for image evaluation and comparison. Existing commercially available phantoms for DBT are expensive and may lack clinically relevant test objects. The purpose of this study is to develop phantoms for DBT evaluation. Methods Four phantoms have been designed and constructed to assess the image quality (IQ) of two DBT systems. The first contains a spiral of 0.3 mm SiC beads in gelatin to measure the tomographic slice thickness profile and uniformity of coverage in a series of tomographic planes. The second contains simulated tumors inclined with respect to the phantom base to assess tomographic image quality. The third has a tilted array of discs with varying contrast and diameter. This phantom was imaged alone and in a stack of TE slabs giving 2 to 10 cm thickness. The fourth has a dual wedge of glandular and adipose simulating materials. One wedge contains discs with varying diameter and thickness; the other supports a mass with six simulated spicules of varying size and a cluster of simulated calcifications. The simulated glandular tissue material varies between 35 and 100% of the total thickness (5.5 cm). Results: All phantoms were scanned successfully. The best IQ comparison was achieved with the dual wedge phantom as demonstrated by the spiculated mass and calcifications. Images were evaluated by two radiologists and one physicist. The projection images and corresponding set of tomographic planes were comparable and the synthesized projection images were inferior to the projection images for both systems. Conclusion: Four phantoms were designed, constructed and imaged on two DBT systems. They successfully demonstrated performance differences between two systems, and between true and synthesized projection images. Future work will incorporate these designs into a single phantom.

  12. Estimation of computed tomography dose in various phantom shapes and compositions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Lae [Dept. of Radiological Science, Yonsei University, Seoul (Korea, Republic of)

    2017-03-15

    The purpose of this study was to investigate CTDI (computed tomography dose index at center) for various phantom shapes, sizes, and compositions by using GATE (geant4 application for tomographic emission) simulations. GATE simulations were performed for various phantom shapes (cylinder, elliptical, and hexagonal prism PMMA phantoms) and phantom compositions (water, PMMA, polyethylene, polyoxymethylene) with various diameters (1-50 cm) at various kVp and mAs levels. The CTDI100center values of cylinder, elliptical, and hexagonal prism phantom at 120 kVp, 200 mAs resulted in 11.1, 13.4, and 12.2 mGy, respectively. The volume is the same, but CTDI{sub 100center} values are different depending on the type of phantom. The water, PMMA, and polyoxymethylene phantom CTDI{sub 100center} values were relatively low as the material density increased. However, in the case of Polyethylene, the CTDI{sub 100center} value was higher than that of PMMA at diameters exceeding 15 cm (CTDI{sub 100center} : 35.0 mGy). And a diameter greater than 30 cm (CTDI{sub 100center} : 17.7 mGy) showed more CTDI{sub 100center} than Water. We have used limited phantoms to evaluate CT doses. In this study, CTDI{sub 100center} values were estimated and simulated by GATE simulation according to the material and shape of the phantom. CT dosimetry can be estimated more accurately by using various materials and phantom shapes close to human body.

  13. A tissue phantom for visualization and measurement of ultrasound-induced cavitation damage.

    Science.gov (United States)

    Maxwell, Adam D; Wang, Tzu-Yin; Yuan, Lingqian; Duryea, Alexander P; Xu, Zhen; Cain, Charles A

    2010-12-01

    Many ultrasound studies involve the use of tissue-mimicking materials to research phenomena in vitro and predict in vivo bioeffects. We have developed a tissue phantom to study cavitation-induced damage to tissue. The phantom consists of red blood cells suspended in an agarose hydrogel. The acoustic and mechanical properties of the gel phantom were found to be similar to soft tissue properties. The phantom's response to cavitation was evaluated using histotripsy. Histotripsy causes breakdown of tissue structures by the generation of controlled cavitation using short, focused, high-intensity ultrasound pulses. Histotripsy lesions were generated in the phantom and kidney tissue using a spherically focused 1-MHz transducer generating 15 cycle pulses, at a pulse repetition frequency of 100 Hz with a peak negative pressure of 14 MPa. Damage appeared clearly as increased optical transparency of the phantom due to rupture of individual red blood cells. The morphology of lesions generated in the phantom was very similar to that generated in kidney tissue at both macroscopic and cellular levels. Additionally, lesions in the phantom could be visualized as hypoechoic regions on a B-mode ultrasound image, similar to histotripsy lesions in tissue. High-speed imaging of the optically transparent phantom was used to show that damage coincides with the presence of cavitation. These results indicate that the phantom can accurately mimic the response of soft tissue to cavitation and provide a useful tool for studying damage induced by acoustic cavitation. Copyright © 2010 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  14. Careful system design. Current interim results of the heat pump field test; Das Gesamtsystem sorgfaeltig auslegen. Aktuelle Zwischenergebnisse im Waermepumpen-Feldtest

    Energy Technology Data Exchange (ETDEWEB)

    Miara, Marek [Fraunhofer-Institut fuer Solare Energiesysteme ISE, Freiburg (Germany)

    2008-09-15

    How efficient are modern electric heat pumps for newly constructed single-family dwellings? This question is to be answered by the project ''Waermepumpen-Effizienz'' (heat pump efficiency), a scientific field test that started in the summer of 2006. The contribution presents first results, including the measured performance data. Further, factors were identified that interfere with the optimum operation of heat pumps. (orig.)

  15. Clinical results after different protocols of combined local heat and radiation

    International Nuclear Information System (INIS)

    Arcangeli, G.; Cividalli, A.; Nervi, C.; Lovisolo, G.

    1983-01-01

    Since 1977, 69 patients with 138 multiple lesions have been treated with combined radiotherapy and hyperthermia, according to 3 protocols. Firstly, radiotherapy was given following a thrice-a-day fractionation scheme of 1.5 to 2 Gy/fraction, up to 60 Gy. Hyperthermia (42.5 0 C/45 min) was applied each other day, immediately after the 2nd radiation fraction. Immediate response resulted significantly higher in the combined group (76% clearances in comparison with 46% after radiotherapy alone). Secondly, tumors received 40 Gy/8 fractions, twice a week, and hyperthermia (42.5 0 C/45 min) was applied with each radiotherapy fraction, either immediately after irradiation (simultaneously) of 4 h later (sequentially). A remarkable improvement of radiation response was obtained, especially with the simultaneous treatment. Thirdly, tumors received 30 Gy/6 fractions, twice a week. Hyperthermia (45 0 C/30 min) was applied simultaneously with each radiotherapy fraction and the surrounding skin was cooled. Complete tumor clearance was achieved in 88% lesions in comparison with 31% after radiotherapy alone. As expected, the incidence of thermal damage on uncooled skin was also increased. In conclusion, the best therapeutic ratio was obtained with low fractional radiotherapy doses and low temperature hyperthermia. (orig.) [de

  16. Internal dosimetry estimates using voxelized reference phantoms for thyroid agents

    International Nuclear Information System (INIS)

    Hoseinian-Azghadi, E.; Rafat-Motavalli, L.; Miri-Hakimabad, H.

    2014-01-01

    This work presents internal dosimetry estimates for diagnostic procedures performed for thyroid disorders by relevant radiopharmaceuticals. The organ doses for 131 Iodine, 123 Iodine and 99m Tc incorporated into the body were calculated for the International Commission on Radiological Protection (ICRP) reference voxel phantoms using the Monte Carlo transport method. A comparison between different thyroid uptakes of iodine in the range of 0–55% was made, and the effect of various techniques for administration of 99m Tc on organ doses was studied. To investigate the necessity of calculating organ dose from all source regions, the major source organ and its contribution to total dose were specified for each target organ. Moreover, we compared effective dose in ICRP voxel phantoms with that in stylized phantoms. In our method, we directly calculated the organ dose without using the S values or SAFs, as is commonly done. Hence, a distribution of the absorbed dose to entire tissues was obtained. The chord length distributions (CLDs) were also computed for the selected source–target pairs to make comparison across the genders. The results showed that the S values for radionuclides in the thyroid are not sufficient for calculating the organ doses, especially for 123 I and 99m Tc. The thyroid and its neighboring organs receive a greater dose as thyroid uptake increases. Our comparisons also revealed an underestimation of organ doses reported for the stylized phantoms compared with the values based on the ICRP voxel phantoms in the uptake range of 5–55%, and an overestimation of absorbed dose by up to 2-fold for Iodine administration using blocking agent and for 99m Tc incorporation. (author)

  17. A phantom design for assessment of detectability in PET imaging

    International Nuclear Information System (INIS)

    Wollenweber, Scott D.; Alessio, Adam M.; Kinahan, Paul E.

    2016-01-01

    Purpose: The primary clinical role of positron emission tomography (PET) imaging is the detection of anomalous regions of 18 F-FDG uptake, which are often indicative of malignant lesions. The goal of this work was to create a task-configurable fillable phantom for realistic measurements of detectability in PET imaging. Design goals included simplicity, adjustable feature size, realistic size and contrast levels, and inclusion of a lumpy (i.e., heterogeneous) background. Methods: The detection targets were hollow 3D-printed dodecahedral nylon features. The exostructure sphere-like features created voids in a background of small, solid non-porous plastic (acrylic) spheres inside a fillable tank. The features filled at full concentration while the background concentration was reduced due to filling only between the solid spheres. Results: Multiple iterations of feature size and phantom construction were used to determine a configuration at the limit of detectability for a PET/CT system. A full-scale design used a 20 cm uniform cylinder (head-size) filled with a fixed pattern of features at a contrast of approximately 3:1. Known signal-present and signal-absent PET sub-images were extracted from multiple scans of the same phantom and with detectability in a challenging (i.e., useful) range. These images enabled calculation and comparison of the quantitative observer detectability metrics between scanner designs and image reconstruction methods. The phantom design has several advantages including filling simplicity, wall-less contrast features, the control of the detectability range via feature size, and a clinically realistic lumpy background. Conclusions: This phantom provides a practical method for testing and comparison of lesion detectability as a function of imaging system, acquisition parameters, and image reconstruction methods and parameters.

  18. Possible association between phantom vibration syndrome and occupational burnout

    Directory of Open Access Journals (Sweden)

    Chen CP

    2014-12-01

    Full Text Available Chao-Pen Chen,1 Chi-Cheng Wu,2 Li-Ren Chang,3 Yu-Hsuan Lin4 1Department of Education, National Taiwan University Hospital, 2Department of Family Medicine, Min-Sheng General Hospital, Taoyuan City, 3Department of Psychiatry, National Taiwan University, College of Medicine, 4Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan Background: Phantom vibration syndrome (PVS and phantom ringing syndrome (PRS occur in many cell phone users. Previous studies have indicated an association between PVS/PRS and job stress. The aim of this study was to determine if PVS/PRS were also associated with occupational burnout.Methods: This was a cross-sectional study of 384 employees of a high-tech company in northern Taiwan. They all completed a phantom vibration and ringing questionnaire, the Hospital Anxiety and Depression Scale, and the Chinese version of the Occupational Burnout Inventory.Results: Significantly more women and people with at least a college education were in the population with PRS and PVS, respectively. Anxiety and depression had no associations with PVS/PRS. Higher scores for personal fatigue, job fatigue, and service target fatigue had an independent impact on the presence of PVS, but only a higher score for service target fatigue had an independent impact on the presence of PRS.Conclusion: The independent association between work-related burnout and PVS/PRS suggests that PVS/PRS may be a harbinger of mental stress or a component of the clinical burnout syndrome, and may even be a more convenient and accurate predictor of occupational burnout. Keywords: phantom vibration syndrome, phantom ringing syndrome, occupational burnout

  19. Ten Year Operating Test Results and Post-Test Analysis of a 1/10 Segment Stirling Sodium Heat Pipe, Phase III

    Science.gov (United States)

    Rosenfeld, John, H; Minnerly, Kenneth, G; Dyson, Christopher, M.

    2012-01-01

    High-temperature heat pipes are being evaluated for use in energy conversion applications such as fuel cells, gas turbine re-combustors, Stirling cycle heat sources; and with the resurgence of space nuclear power both as reactor heat removal elements and as radiator elements. Long operating life and reliable performance are critical requirements for these applications. Accordingly, long-term materials compatibility is being evaluated through the use of high-temperature life test heat pipes. Thermacore, Inc., has carried out a sodium heat pipe 10-year life test to establish long-term operating reliability. Sodium heat pipes have demonstrated favorable materials compatibility and heat transport characteristics at high operating temperatures in air over long time periods. A representative one-tenth segment Stirling Space Power Converter heat pipe with an Inconel 718 envelope and a stainless steel screen wick has operated for over 87,000 hr (10 yr) at nearly 700 C. These life test results have demonstrated the potential for high-temperature heat pipes to serve as reliable energy conversion system components for power applications that require long operating lifetime with high reliability. Detailed design specifications, operating history, and post-test analysis of the heat pipe and sodium working fluid are described.

  20. Excess heat from kraft pulp mills: Trade-offs between internal and external use in the case of Sweden-Part 2: Results for future energy market scenarios

    International Nuclear Information System (INIS)

    Joensson, Johanna; Svensson, Inger-Lise; Berntsson, Thore; Moshfegh, Bahram

    2008-01-01

    In this paper the trade-off between internal and external use of excess heat from a kraft pulp mill is investigated for four different future energy market scenarios. The work follows the methodology described in Svensson et al. [2008. Excess heat from kraft pulp mills: trade-offs between internal and external use in the case of Sweden-Part 1: methodology. Energy Policy, submitted for publication], where a systematic approach is proposed for investigating the potential for profitable excess heat cooperation. The trade-off is analyzed by economic optimization of an energy system model consisting of a pulp mill and an energy company (ECO). In the model, investments can be made, which increase the system's energy efficiency by utilization of the mill's excess heat, as well as investments that increase the electricity production. The results show that the trade-off depends on energy market prices, the district heating demand and the type of existing heat production. From an economic point of view, external use of the excess heat is preferred for all investigated energy market scenarios if the mill is studied together with an ECO with a small heat load. For the cases with medium or large district heating loads, the optimal use of excess heat varies with the energy market price scenarios. However, from a CO 2 emissions perspective, external use is preferred, giving the largest reduction of global emissions in most cases

  1. Vitrification of Hanford wastes in a joule-heated ceramic melter and evaluation of resultant canisterized product

    International Nuclear Information System (INIS)

    Chapman, C.C.; Buelt, J.L.; Slate, S.C.; Katayama, Y.B.; Bunnell, L.R.

    1979-08-01

    Experience gained in the week-long vitrification test and characterization of the glass produced in the run support the following conclusions: The Hanford waste simulated in this test can be readily vitrified in a joule-heated ceramic melter. Physical properties of the molten glass were entirely compatible with melter operation. The average feed rate of 106 kg/h is high enough to make the ceramic melter a feasible piece of equipment for vitrifying Hanford wastes. The glass produced in this trial had good chemical durability, 6(10) -5 g/cm 2 -d. When one of the canisters was purposely dropped onto a steel pad, the damage was limited to deformation of the steel can in the impact area, cracking of a weld, and fracturing of glass in the immediate vicinity of the impact area. No glass was released from the canister as a result of the drop test. The results of this vitrification test support the technical feasibility of vitrifying Hanford wastes by means of a joule-heated ceramic melter. Surface area for large glass castings is equivalent to the mass median particle diameters between 4.27 cm (1.75 in.) and 8.91 cm (3.51 in.) even when allowed to cool rapidly by standing in ambient air. Large canisters (up to 0.91 m in dia) can be cast without large voids while standing in air if the fill rate is over 100 kg/h. 34 figures, 10 tables

  2. Thermodynamic properties of xanthone: Heat capacities, phase-transition properties, and thermodynamic-consistency analyses using computational results

    International Nuclear Information System (INIS)

    Chirico, Robert D.; Kazakov, Andrei F.

    2015-01-01

    Highlights: • Heat capacities were measured for the temperature range (5 to 520) K. • The enthalpy of combustion was measured and the enthalpy of formation was derived. • Thermodynamic-consistency analysis resolved inconsistencies in literature enthalpies of sublimation. • An inconsistency in literature enthalpies of combustion was resolved. • Application of computational chemistry in consistency analysis was demonstrated successfully. - Abstract: Heat capacities and phase-transition properties for xanthone (IUPAC name 9H-xanthen-9-one and Chemical Abstracts registry number [90-47-1]) are reported for the temperature range 5 < T/K < 524. Statistical calculations were performed and thermodynamic properties for the ideal gas were derived based on molecular geometry optimization and vibrational frequencies calculated at the B3LYP/6-31+G(d,p) level of theory. These results are combined with sublimation pressures from the literature to allow critical evaluation of inconsistent enthalpies of sublimation for xanthone, also reported in the literature. Literature values for the enthalpy of combustion of xanthone are re-assessed, a revision is recommended for one result, and a new value for the enthalpy of formation of the ideal gas is derived. Comparisons with thermophysical properties reported in the literature are made for all other reported and derived properties, where possible

  3. Phantom cosmology without Big Rip singularity

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-23

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

  4. Phantom inflation and the 'Big Trip'

    International Nuclear Information System (INIS)

    Gonzalez-Diaz, Pedro F.; Jimenez-Madrid, Jose A.

    2004-01-01

    Primordial inflation is regarded to be driven by a phantom field which is here implemented as a scalar field satisfying an equation of state p=ωρ, with ω-1. Being even aggravated by the weird properties of phantom energy, this will pose a serious problem with the exit from the inflationary phase. We argue, however, in favor of the speculation that a smooth exit from the phantom inflationary phase can still be tentatively recovered by considering a multiverse scenario where the primordial phantom universe would travel in time toward a future universe filled with usual radiation, before reaching the big rip. We call this transition the 'Big Trip' and assume it to take place with the help of some form of anthropic principle which chooses our current universe as being the final destination of the time transition

  5. Phantom cosmology without Big Rip singularity

    International Nuclear Information System (INIS)

    Astashenok, Artyom V.; Nojiri, Shin'ichi; Odintsov, Sergei D.; Yurov, Artyom V.

    2012-01-01

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

  6. Results of out-of-pile experiments to investigate the possibilities of cooling a core melt with internal heat production

    International Nuclear Information System (INIS)

    Fieg, G.

    1976-01-01

    After serious hypothetical reactor accidents, melted core materials with internal heat production can occur in large quantities. A retention of these molten core masses within the containment must be ensured. The knowledge of the heat transport from volume-heated layers is necessary to clarify this matter. (orig./LH) [de

  7. Pediatric phantoms for use in dosimetric calculations

    International Nuclear Information System (INIS)

    Shoup, R.L.; Hwang, J.L.; Poston, J.W.; Warner, G.G.

    1976-01-01

    Estimating absorbed doses to children from external and internal radiation sources has become important to the nuclear industry and pediatric nuclear medicine. The Medical Physics and Internal Dosimetry Section at ORNL has recently completed the design of mathematical representations of children of ages newborn, 1 year, and 5 years old. These mathematical representations will be referred to as pediatric phantoms. Using these phantoms, relevant energy deposition data have been developed which establish a meaningful model for use in estimating radiation dose to children

  8. Optimisation of radioprotection of patients in nuclear medicine: assessment of doses for the new ICRP's reference voxelized phantoms

    International Nuclear Information System (INIS)

    Hadid, L.; Blanchardon, E.; Desbree, A.; Makovicka, L.; Zankl, M.

    2010-01-01

    As the ICPR (International Commission on Radiological Protection) decided to adopt voxelized phantoms to emulate a reference adult, the authors report the validation of calculations of the SFAs (specific absorbed fractions) for the new ICPR's reference phantoms. After a presentation of these phantoms, the authors briefly present the OEDIPE software which is used to compute the SAFs and notably the absorbed doses. They discuss the results obtained for the SAFs (for photons and for electrons) and for the doses

  9. First results of saturation curve measurements of heat-resistant steel using GEANT4 and MCNP5 codes

    International Nuclear Information System (INIS)

    Hoang, Duc-Tam; Tran, Thien-Thanh; Le, Bao-Tran; Vo, Hoang-Nguyen; Chau, Van-Tao; Tran, Kim-Tuyet; Huynh, Dinh-Chuong

    2015-01-01

    A gamma backscattering technique is applied to calculate the saturation curve and the effective mass attenuation coefficient of material. A NaI(Tl) detector collimated by collimator of large diameter is modeled by Monte Carlo technique using both MCNP5 and GEANT4 codes. The result shows a good agreement in response function of the scattering spectra for the two codes. Based on such spectra, the saturation curve of heat-resistant steel is determined. The results represent a strong confirmation that it is appropriate to use the detector collimator of large diameter to obtain the scattering spectra and this work is also the basis of experimental set-up for determining the thickness of material. (author)

  10. Results and analysis of high heat flux tests on a full scale vertical target prototype of ITER divertor

    International Nuclear Information System (INIS)

    Missirlian, M.; Escourbiac, F.; Schlosser, J.; Durocher, A.; Bobin-Vastra, I.

    2004-01-01

    After an extensive development program, a Full-Scale Divertor Target prototype (VTFS) manufactured with all the main features of the corresponding ITER divertor, was intensively tested in the high heat flux FE200 facility. The prototype consists of four units having a full mono-block geometry. The lower part (CFC armour) and the upper part (W armour) of each mono-block were joined to the solution annealed, quenched and cold worked CuCrZr tube by HIP technique. The CFC mono-block was successfully tested up to 1000 cycles at 23 MW/m 2 without any indication of failure. This value is well beyond the ITER design target of 300 cycles at 20 MW/m 2 . The W mono-block endured ∼600 cycles at 10 MW/m 2 . This value of flux is one order of magnitude higher than the ITER design target for the upper part of the vertical target. Fatigue damage is observed when pursuing the cycling up to 15 MW/m 2 . A first stress analysis seems to predict these factual results. However, macro-graphic examinations should bring a better damage valuation. Meanwhile, the fatigue testing will continue on the W healthy part of the VTFS prototype with castellation located on the heated surface (reducing the stresses close to the W-Cu interface). (authors)

  11. Results and analysis of high heat flux tests on a full scale vertical target prototype of ITER divertor

    Energy Technology Data Exchange (ETDEWEB)

    Missirlian, M.; Escourbiac, F.; Schlosser, J.; Durocher, A. [Association Euratom-CEA, Centre d' Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Merola, M. [EFDA Close Support Unit, Garching (Germany); Bobin-Vastra, I. [Framatome, 71 - Le Creusot (France)

    2004-07-01

    After an extensive development program, a Full-Scale Divertor Target prototype (VTFS) manufactured with all the main features of the corresponding ITER divertor, was intensively tested in the high heat flux FE200 facility. The prototype consists of four units having a full mono-block geometry. The lower part (CFC armour) and the upper part (W armour) of each mono-block were joined to the solution annealed, quenched and cold worked CuCrZr tube by HIP technique. The CFC mono-block was successfully tested up to 1000 cycles at 23 MW/m{sup 2} without any indication of failure. This value is well beyond the ITER design target of 300 cycles at 20 MW/m{sup 2}. The W mono-block endured {approx}600 cycles at 10 MW/m{sup 2}. This value of flux is one order of magnitude higher than the ITER design target for the upper part of the vertical target. Fatigue damage is observed when pursuing the cycling up to 15 MW/m{sup 2}. A first stress analysis seems to predict these factual results. However, macro-graphic examinations should bring a better damage valuation. Meanwhile, the fatigue testing will continue on the W healthy part of the VTFS prototype with castellation located on the heated surface (reducing the stresses close to the W-Cu interface). (authors)

  12. Shifts of heat availability and stressful temperatures in Russian Federation result in gains and losses of wheat thermal suitability

    Science.gov (United States)

    Di Paola, Arianna; Caporaso, Luca; Santini, Monia; Di Paola, Francesco; Vasenev, Ivan; Valentini, Riccardo

    2017-04-01

    Climate changes are likely to shift the suitability of lands devoted to cropping systems. We explored the past-to-future thermal suitability of Russian Federation for wheat (Triticum aestivum) culture through an ensemble of bias corrected CMIP5-GCMs outputs considering two representative concentration pathways (RCP 4.5 and 8.5). Thermal suitability assesses where wheat heat requirement, counted from suggested sowing dates, is satisfied without the occurrence of stressful hot and frost temperatures. Thermal requirement was estimated by means of phenological observations on soft wheat involving different wheat cultivar collected in different regions of Russian Federation, Azerbaidhan, Kazakhstan and Tadzhikistan, whilst stressful temperatures were taken from a literature survey. Results showed projected geographical shift of heat resource toward the north-eastern regions, currently mainly covered by forests and croplands, but also an increase of very hot temperatures in the most productive areas of the southern regions. Gains and losses were then quantified and discussed from both agronomical and climatic perspective.

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

    Science.gov (United States)

    Lee, Choonsik; Lee, Choonik; Lee, Jai-Ki

    2006-11-01

    -Man, were obtained from literature sources. The absorbed doses for lungs, oesophagus, liver and kidneys that could be affected by arm structures in the lateral irradiation geometry were obtained for both classes of phantoms in lateral monoenergetic photon irradiation geometries. As expected, those organs in the ORNL phantoms received apparently higher absorbed doses than those in the voxel phantoms. The overestimation is mainly attributed to the relatively poor representation of the arm structure in the ORNL phantom in which the arm bones are embedded within the regions describing the phantom's torso. The results of this study suggest that the overestimation of organ doses, due to unrealistic arm representation, should be taken into account when stylized phantoms are employed for equivalent or effective dose estimates, especially in the case of an irradiation scenario with dominating lateral exposure. For such a reason, the stylized phantom arm structure definition should be revised in order to obtain more realistic evaluations.

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

    International Nuclear Information System (INIS)

    Lee, Choonsik; Lee, Choonik; Lee, Jai-Ki

    2006-01-01

    -Man, were obtained from literature sources. The absorbed doses for lungs, oesophagus, liver and kidneys that could be affected by arm structures in the lateral irradiation geometry were obtained for both classes of phantoms in lateral monoenergetic photon irradiation geometries. As expected, those organs in the ORNL phantoms received apparently higher absorbed doses than those in the voxel phantoms. The overestimation is mainly attributed to the relatively poor representation of the arm structure in the ORNL phantom in which the arm bones are embedded within the regions describing the phantom's torso. The results of this study suggest that the overestimation of organ doses, due to unrealistic arm representation, should be taken into account when stylized phantoms are employed for equivalent or effective dose estimates, especially in the case of an irradiation scenario with dominating lateral exposure. For such a reason, the stylized phantom arm structure definition should be revised in order to obtain more realistic evaluations. (note)

  15. ANTHROPOMORPHIC PHANTOMS FOR ASSESSMENT OF STRAIN IMAGING METHODS INVOLVING SALINE-INFUSED SONOHYSTEROGRAPHY

    Science.gov (United States)

    Hobson, Maritza A.; Madsen, Ernest L.; Frank, Gary R.; Jiang, Jingfeng; Shi, Hairong; Hall, Timothy J.; Varghese, Tomy

    2008-01-01

    Two anthropomorphic uterine phantoms were developed which allow assessment and comparison of strain imaging systems adapted for use with saline-infused sonohysterography (SIS). Tissue-mimicking (TM) materials consist of dispersions of safflower oil in gelatin. TM fibroids are stiffer than the TM myometrium/cervix and TM polyps are softer. The first uterine phantom has 3-mm diameter TM fibroids randomly distributed in TM myometrium. The second uterine phantom has a 5-mm and an 8-mm spherical TM fibroid in addition to a 5-mm spherical and a 12.5-mm long (medicine-capsule-shaped) TM endometrial polyp protruding into the endometrial cavity; also, a 10-mm spherical TM fibroid projects from the serosal surface. Strain images using the first phantom show the stiffer 3-mm TM fibroids in the myometrium. Results from the second uterine phantom show that, as expected, parts of inclusions projecting into the uterine cavity will appear very stiff, whether they are stiff or soft. Results from both phantoms show that even though there is a five-fold difference in the Young’s moduli values, there is not a significant difference in the strain in the transition from the TM myometrium to the TM fat. These phantoms allow for realistic comparison and evolution of SIS strain imaging techniques and can aid clinical personnel to develop skills for SIS strain imaging. PMID:18514999

  16. Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program

    Directory of Open Access Journals (Sweden)

    Jalil Pirayesh Islamian

    2012-03-01

    Full Text Available Introduction Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. Materials and Methods The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. Results The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and rods. The calculated contrasts of the rods were 0.774, 0.627, 0.575, 0.372, 0.191, and 0.132 for an experiment with the rods diameters of 31.8, 25.4, 19.1, 15.9, 12.7, and 9.5 mm, respectively. The calculated contrasts of simulated rods were 0.661, 0.527, 0.487, 0.400, 0.23, and 0.2 for cold rods and also 0.92, 0.91, 0.88, 0.81, 0.76, and 0.56 for hot rods. Reconstructed spatial tomographic resolution of both experiment and simulated SPECTs of the phantom obtained about 9.5 mm. An executable phantom file and an input phantom file were created for the SIMIND Monte Carlo program. Conclusion This phantom may be used for simulated SPECT systems and would be ideal for verification of the simulated systems with real ones by comparing the results of quality control and image evaluation. It is also envisaged that this phantom could be used with a range of radionuclide doses in simulation situations such as cold, hot, and background uptakes for the assessment of detection

  17. 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.

  18. Porous phantoms for PET and SPECT performance evaluation and quality assurance

    International Nuclear Information System (INIS)

    DiFilippo, Frank P.; Price, James P.; Kelsch, Daniel N.; Muzic, Raymond F. Jr.

    2004-01-01

    Characterization of PET and SPECT imaging performance often requires phantoms with complex radionuclide distributions. For example, lesion detection studies use multiple spherical regions of specific target-to-background ratios to simulate cancerous lesions. Such complex distributions are typically created using phantoms with multiple fillable chambers. However, such phantoms are typically difficult and time-consuming to prepare accurately and reproducibly. A new approach using a single-chamber phantom with a porous core can overcome these difficulties. Methods: Prototypes of two designs of porous core phantoms were produced and evaluated. The 'hot spheres' phantom contained a multitude of simulated spherical lesions with diameters ranging from 6.35 to 25.4 mm ('multi-resolution' slice) and with lesion-to-background ratios ranging from 1.6 to 4.4 ('multi-contrast' slice). The 'multi-attenuation' phantom consisted of two halves. One half contained a porous core to produce regions of different attenuation but uniform activity. The other half mimicked the NEMA-94 design with cold inserts of different attenuation. Results: Both phantoms produced the expected radionuclide distributions while requiring the preparation of only a single radionuclide solution and with much reduced preparation time. In images taken on clinical PET and SPECT scanners, the porous core structures were found to contribute negligible background noise or artifact. The measured lesion-to-background ratios from the hot spheres phantom differed slightly from calculated values, with the differences attributed mainly to uncertainty in pore diameter. The measured attenuation coefficients from the multi-attenuation phantom agreed well with expected values. However, it was found that trapped air bubbles due to manufacturing defects in the porous core could potentially cause quantitative errors. Conclusion: The hot spheres and multi-attenuation porous phantoms exhibited a wide range of imaging features

  19. An Alternative Method of Evaluating 1540NM Exposure Laser Damage using an Optical Tissue Phantom

    National Research Council Canada - National Science Library

    Jindra, Nichole M; Figueroa, Manuel A; Rockwell, Benjamin A; Chavey, Lucas J; Zohner, Justin J

    2006-01-01

    An optical phantom was designed to physically and optically resemble human tissue, in an effort to provide an alternative for detecting visual damage resulting from inadvertent exposure to infrared lasers...

  20. Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program

    International Nuclear Information System (INIS)

    Pirayesh Islamian, J.; Bahreyni Toosi, M. T.; Momennezhad, M.; Naseri, Sh.; Ljungberg, M.

    2012-01-01

    Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and rods. The calculated contrasts of the rods were 0.774, 0.627, 0.575, 0.372, 0.191, and 0.132 for an experiment with the rods diameters of 31.8, 25.4, 19.1, 15.9, 12.7, and 9.5 mm, respectively. The calculated contrasts of simulated rods were 0.661, 0.527, 0.487, 0.400, 0.23, and 0.2 for cold rods and also 0.92, 0.91, 0.88, 0.81, 0.76, and 0.56 for hot rods. Reconstructed spatial tomographic resolution of both experiment and simulated SPECTs of the phantom obtained about 9.5 mm. An executable phantom file and an input phantom file were created for the SIMIND Monte Carlo program. This phantom may be used for simulated SPECT systems and would be ideal for verification of the simulated systems with real ones by comparing the results of quality control and image evaluation. It is also envisaged that this phantom could be used with a range of radionuclide doses in simulation situations such as cold, hot, and background uptakes for the assessment of detection characteristics when a new similar clinical SPECT procedure is being simulated.

  1. Development of 5 and 10 years old infant phantoms based on polygonal meshes

    International Nuclear Information System (INIS)

    Lima, Vanildo Junior de Melo; Kramer, Richard; Cassola, Vagner Ferreira; Lira, Carlos Alberto Brayner de Oliveira; Khoury, Helen Jamil; Vieira, Jose Wilson; Universidade de Pernambuco

    2011-01-01

    This paper focuses the development of reference infant phantoms of 5 and 10 years old to be used in calculation of equivalent doses in the area of radiological protection. The method uses tools developed for the modelling of 3D objects. The forms and positions are available in the literature. The mass values of each organ and tissue were adjusted according to the reference data published by the International Commission Radiological Protection. The results are presented in image of organs and tissues, and in tables. Dosimetric calculations show concordance with adult and infant phantoms, considering the differences among phantoms

  2. Low cost phantom for computed radiology; Objeto de teste de baixo custo para radiologia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Travassos, Paulo Cesar B.; Magalhaes, Luis Alexandre G., E-mail: pctravassos@ufrj.br [Universidade do Estado do Rio de Janeiro (IBRGA/UERJ), RJ (Brazil). Laboratorio de Ciencias Radiologicas; Augusto, Fernando M.; Sant' Yves, Thalis L.A.; Goncalves, Elicardo A.S. [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil); Botelho, Marina A. [Hospital Universitario Pedro Ernesto (UERJ), Rio de Janeiro, RJ (Brazil)

    2012-08-15

    This article presents the results obtained from a low cost phantom, used to analyze Computed Radiology (CR) equipment. The phantom was constructed to test a few parameters related to image quality, as described in [1-9]. Materials which can be easily purchased were used in the construction of the phantom, with total cost of approximately U$100.00. A bar pattern was placed only to verify the efficacy of the grids in the spatial resolution determination, and was not included in the budget because the data was acquired from the grids. (author)

  3. Thermodynamics of Phantom Energy Accreting onto a Black Hole in Einstein—Power—Maxwell Gravity

    International Nuclear Information System (INIS)

    Abbas, G.; Ramzan, R. M.

    2013-01-01

    We investigate the phantom energy accretion onto a 3D black hole formulated in the Einstein—Power—Maxwell theory, and present the conditions for critical accretion of phantom energy onto the black hole. Further, we discuss the thermodynamics of phantom energy accreting onto the black hole and find that the first law of thermodynamics is easily satisfied while the second law and the generalized second law of thermodynamics remain invalid and conditionally valid, respectively. The results for the Banados—Teitelboim—Zanelli black hole can be recovered by taking Maxwellian contribution equal to zero

  4. ``Phantom'' Modes in Ab Initio Tunneling Calculations: Implications for Theoretical Materials Optimization, Tunneling, and Transport

    Science.gov (United States)

    Barabash, Sergey V.; Pramanik, Dipankar

    2015-03-01

    Development of low-leakage dielectrics for semiconductor industry, together with many other areas of academic and industrial research, increasingly rely upon ab initio tunneling and transport calculations. Complex band structure (CBS) is a powerful formalism to establish the nature of tunneling modes, providing both a deeper understanding and a guided optimization of materials, with practical applications ranging from screening candidate dielectrics for lowest ``ultimate leakage'' to identifying charge-neutrality levels and Fermi level pinning. We demonstrate that CBS is prone to a particular type of spurious ``phantom'' solution, previously deemed true but irrelevant because of a very fast decay. We demonstrate that (i) in complex materials, phantom modes may exhibit very slow decay (appearing as leading tunneling terms implying qualitative and huge quantitative errors), (ii) the phantom modes are spurious, (iii) unlike the pseudopotential ``ghost'' states, phantoms are an apparently unavoidable artifact of large numerical basis sets, (iv) a presumed increase in computational accuracy increases the number of phantoms, effectively corrupting the CBS results despite the higher accuracy achieved in resolving the true CBS modes and the real band structure, and (v) the phantom modes cannot be easily separated from the true CBS modes. We discuss implications for direct transport calculations. The strategy for dealing with the phantom states is discussed in the context of optimizing high-quality high- κ dielectric materials for decreased tunneling leakage.

  5. The underground heat storage for solar-assisted district heating in Neckarsulm. First measuring results; Der Erdsonden-Waermespeicher fuer die solarunterstuetzte Nahwaermeversorgung in Neckarsulm. Erste Messergebnisse

    Energy Technology Data Exchange (ETDEWEB)

    Seiwald, H.; Hahne, E. [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik und Waermetechnik

    1998-12-31

    A solar-assisted district heating system with seasonal underground heat storage is currently under construction in Neckarsulm (Baden-Wurttemberg). In the new residential area approximately 1,300 flats are going to be built during the next years. The overall energy demand (hot water and space heating) is supposed to be covered by 50% with solar energy. During the first phase the project will be subsidised in the frame of the BMBF programme `Solarthermie 2000, Teilprogramm III`. A solar plant consisting of 2,700 square metres of collectors, a buffer tank (100 cubic metre) and an underground heat storage with a volume of approx. 20,000 cubic metres will be constructed by the end of 1998. It will be the first plant in Germany where thermal energy generated of solar energy is stored at high temperatures (up to 80 C) directly in the earth and utilised without a heat pump. (orig.) [Deutsch] In Neckarsulm (Baden-Wuerttemberg) befindet sich derzeit eine solar unterstuetzte Nahwaermeversorgung mit saisonalem Endsonden-Waermespeicher im Aufbau. Im Neubaugebiet Amorbach werden in den naechsten Jahren rund 1300 Wohneinheiten entstehen, deren Gesamtwaermebedarf (Warmwasser und Raumheizung) zu rund 50% mit Sonnenenergie gedeckt werden soll. In der ersten Phase wird das Projekt im Rahmen des BMBF-Programms `Solarthermie 2000, Teilprogramm III` gefoerdert. Bis Ende 1998 wird eine Solaranlage bestehend aus 2.700 m{sup 2} Kollektoren, einem Pufferspeicher (100 m{sup 3}) und einem Endsonden-Waermespeicher mit einem Volumen von ca. 20.000 m{sup 3} erstellt. Damit wird in Deutschland erstmalig eine Anlage realisiert, bei der solar erzeugte Waerme auf hohem Temperaturniveau (bis zu 80 C) direkt im Erdreich gespeichert und ohne Waermepumpe genutzt werden soll. (orig.)

  6. Application of a sitting MIRD phantom for effective dose calculations

    International Nuclear Information System (INIS)

    Olsher, R. H.; Van Riper, K. A.

    2005-01-01

    In typical realistic scenarios, dose factors due to 60 Co contaminated steel, used in consumer products, cannot be approximated by standard exposure geometries. It is then necessary to calculate the effective dose using an appropriate anthropomorphic phantom. MCNP calculations were performed using a MIRD human model in two settings. In the first, a male office worker is sitting in a chair containing contaminated steel, surrounded by contaminated furniture. In the second, a male driver is seated inside an automobile, the steel of which is uniformly contaminated. To accurately calculate the dose to lower body organs, especially the gonads, it was essential to modify the MIRD model to simulate two sitting postures: chair and driving position. The phantom modifications are described, and the results of the calculations are presented. In the case of the automobile scenarios, results are compared to those obtained using an isotropic fluence-to-dose conversion function. (authors)

  7. Monte Carlo simulation of a mammographic test phantom

    International Nuclear Information System (INIS)

    Hunt, R. A.; Dance, D. R.; Pachoud, M.; Carlsson, G. A.; Sandborg, M.; Ullman, G.

    2005-01-01

    A test phantom, including a wide range of mammographic tissue equivalent materials and test details, was imaged on a digital mammographic system. In order to quantify the effect of scatter on the contrast obtained for the test details, calculations of the scatter-to-primary ratio (S/P) have been made using a Monte Carlo simulation of the digital mammographic imaging chain, grid and test phantom. The results show that the S/P values corresponding to the imaging conditions used were in the range 0.084-0.126. Calculated and measured pixel values in different regions of the image were compared as a validation of the model and showed excellent agreement. The results indicate the potential of Monte Carlo methods in the image quality-patient dose process optimisation, especially in the assessment of imaging conditions not available on standard mammographic units. (authors)

  8. A dynamic phantom for radionuclide renography

    International Nuclear Information System (INIS)

    Heikkinen, J.O.

    1999-01-01

    The aim of the study was to develop and test a dynamic phantom simulating radionuclide renography. The phantom consisted of five partly lead covered plastic containers simulating kidneys, heart, bladder and background (soft tissues, liver and spleen). Dynamics were performed with multiple movable steel plates between containers and a gamma camera. Control of the plates is performed manually with a stopwatch following exact time schedules. The containers were filled with activities ( 99m Tc) which produce count rates close to clinical situations. Count rates produced by the phantom were compared with ten clinical renography cases: five 99m Tc MAG3 and five 99m Tc DTPA examinations. Two phantom simulations were repeated three times with separate fillings, acquisitions and analyses. Precision errors as a coefficient of variation (CV) of repeated measurements were calculated and theoretical values were compared with the corresponding measured ones. A multicentre comparison was made between 19 nuclear medicine laboratories and three clinical cases were simulated with the phantom. Correlations between count rates produced by the phantom and clinical studies were r=0.964 for 99m Tc MAG3 (p 99m Tc DTPA (p max was 4.0±1.6%. Images and curves of the scanned phantom were close to a real patient in all 19 laboratories but calculated parameters varied: the difference between theoretical and measured values for T max was 6.8±6.2%. The difference between laboratories is most probably due to variations in acquisition protocols and analysis programs: 19 laboratories with 18 different protocols and 8 different programs. The dynamics were found to be repeatable and suitable for calibration purposes for radionuclide renography programs and protocols as well as for multicentre comparisons. (author)

  9. The effect of magnetic nanoparticles on the acoustic properties of tissue-mimicking agar-gel phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Józefczak, A., E-mail: aras@amu.edu.pl [Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Kaczmarek, K. [Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Kubovčíková, M. [Institute of Experimental Physics, Slovak Academy of Sciences, Košice (Slovakia); Rozynek, Z.; Hornowski, T. [Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland)

    2017-06-01

    In ultrasonic hyperthermia, ultrasound-induced heating is achieved by the absorption of wave energy and its conversion into heat. The effectiveness of ultrasounds can be improved by using sonosensitisers that greatly attenuate ultrasonic waves and then dissipate the acquired energy in the form of heat. One possible candidate for such a sonosensitiser are superparamagnetic iron oxide nanoparticles. Here, we used magnetic nanoparticles embedded in a tissue-mimicking agar-gel matrix. Such tissue-mimicking phantoms possess acoustic properties similar to those of real tissues, and are used as a tool for performance testing and optimisation of medical ultrasound systems. In this work, we studied the effect of magnetic nanoparticles on the acoustic properties of agar-gel phantoms, including the attenuation of ultrasonic waves. - Highlights: • Ultrasonic insertion technique is used to study acoustic properties of agar-gel phantoms with and without magnetic particles. • The addition of magnetic nanoparticles improves effectiveness of ultrasound heating in agar phantoms. • Acoustics properties of a pure agar-gel phantom are altered by adding nanoparticles.

  10. Electrically driven heat pumps. Latest results from research and field tests; Elektrisch angetriebene Waermepumpen. Aktuelle Ergebnisse aus Forschung und Feldtests

    Energy Technology Data Exchange (ETDEWEB)

    Braungardt, Simon; Guenther, Danny; Miara, Marek; Wapler, Jeannette [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Wessing, Werner [E.ON Ruhrgas AG, Essen (Germany)

    2013-11-01

    Electric heat pumps have become firmly established in the German heating market. In recent years they have gained an eight to ten per cent share of the market. Approximately every fourth new building is heated with a heat pump. Whereas until a few years ago ground source heat pumps were still sold the most, the sales figures have shifted in recent years in favour of air source heat pumps. Carefully planned, heat pump systems compare very economically with other heating systems, whereby their higher procurement costs are offset by their lower energy and operating costs. Heat pumps are also competitive in terms of their ecological balance. This situation is continually improving with the growing proportion of renewable energies used for supplying electricity. [German] Auf dem deutschen Heizungsmarkt haben sich elektrische Waermepumpen als feste Groesse etabliert. Ihr Marktanteil lag in den letzten Jahren zwischen acht und zehn Prozent. Etwa jeder vierte Neubau wird mit einer Waermepumpe beheizt. Waehrend vor einigen Jahren noch ueberwiegend Erdreich-Waermepumpen verkauft wurden, haben sich die Verkaufszahlen in den letzten Jahren zugunsten der Aussenluft-Waermepumpen verschoben. Sorgfaeltig geplant, koennen Waermepumpenanlagen oekonomisch sehr gut gegenueber anderen Heizsystemen bestehen. Den hoeheren Anschaffungskosten stehen niedrigere Energie- und Betriebskosten gegenueber. Auch in der oekologischen Bilanz sind Waermepumpen konkurrenzfaehig. Die Position verbessert sich stetig mit dem wachsenden Anteil erneuerbarer Energien bei der Stromversorgung.

  11. SU-E-T-114: Analysis of MLC Errors On Gamma Pass Rates for Patient-Specific and Conventional Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Sterling, D; Ehler, E [University of Minnesota, Minneapolis, MN (United States)

    2015-06-15

    Purpose: To evaluate whether a 3D patient-specific phantom is better able to detect known MLC errors in a clinically delivered treatment plan than conventional phantoms. 3D printing may make fabrication of such phantoms feasible. Methods: Two types of MLC errors were introduced into a clinically delivered, non-coplanar IMRT, partial brain treatment plan. First, uniformly distributed random errors of up to 3mm, 2mm, and 1mm were introduced into the MLC positions for each field. Second, systematic MLC-bank position errors of 5mm, 3.5mm, and 2mm due to simulated effects of gantry and MLC sag were introduced. The original plan was recalculated with these errors on the original CT dataset as well as cylindrical and planar IMRT QA phantoms. The original dataset was considered to be a perfect 3D patient-specific phantom. The phantoms were considered to be ideal 3D dosimetry systems with no resolution limitations. Results: Passing rates for Gamma Index (3%/3mm and no dose threshold) were calculated on the 3D phantom, cylindrical phantom, and both on a composite and field-by-field basis for the planar phantom. Pass rates for 5mm systematic and 3mm random error were 86.0%, 89.6%, 98% and 98.3% respectively. For 3.5mm systematic and 2mm random error the pass rates were 94.7%, 96.2%, 99.2% and 99.2% respectively. For 2mm systematic error with 1mm random error the pass rates were 99.9%, 100%, 100% and 100% respectively. Conclusion: A 3D phantom with the patient anatomy is able to discern errors, both severe and subtle, that are not seen using conventional phantoms. Therefore, 3D phantoms may be beneficial for commissioning new treatment machines and modalities, patient-specific QA and end-to-end testing.

  12. SU-E-T-114: Analysis of MLC Errors On Gamma Pass Rates for Patient-Specific and Conventional Phantoms

    International Nuclear Information System (INIS)

    Sterling, D; Ehler, E

    2015-01-01

    Purpose: To evaluate whether a 3D patient-specific phantom is better able to detect known MLC errors in a clinically delivered treatment plan than conventional phantoms. 3D printing may make fabrication of such phantoms feasible. Methods: Two types of MLC errors were introduced into a clinically delivered, non-coplanar IMRT, partial brain treatment plan. First, uniformly distributed random errors of up to 3mm, 2mm, and 1mm were introduced into the MLC positions for each field. Second, systematic MLC-bank position errors of 5mm, 3.5mm, and 2mm due to simulated effects of gantry and MLC sag were introduced. The original plan was recalculated with these errors on the original CT dataset as well as cylindrical and planar IMRT QA phantoms. The original dataset was considered to be a perfect 3D patient-specific phantom. The phantoms were considered to be ideal 3D dosimetry systems with no resolution limitations. Results: Passing rates for Gamma Index (3%/3mm and no dose threshold) were calculated on the 3D phantom, cylindrical phantom, and both on a composite and field-by-field basis for the planar phantom. Pass rates for 5mm systematic and 3mm random error were 86.0%, 89.6%, 98% and 98.3% respectively. For 3.5mm systematic and 2mm random error the pass rates were 94.7%, 96.2%, 99.2% and 99.2% respectively. For 2mm systematic error with 1mm random error the pass rates were 99.9%, 100%, 100% and 100% respectively. Conclusion: A 3D phantom with the patient anatomy is able to discern errors, both severe and subtle, that are not seen using conventional phantoms. Therefore, 3D phantoms may be beneficial for commissioning new treatment machines and modalities, patient-specific QA and end-to-end testing

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-15

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

  14. Mammography dosimetry using an in-house developed polymethyl methacrylate phantom

    International Nuclear Information System (INIS)

    Sharma, R.; Sharma, S. D.; Mayya, Y. S.; Chourasiya, G.

    2012-01-01

    Phantom-based measurements in mammography are well-established for quality assurance (QA) and quality control (QC) procedures involving equipment performance and comparisons of X-ray machines. Polymethyl methacrylate (PMMA) is among the best suitable materials for simulation of the breast. For carrying out QA/QC exercises in India, a mammographic PMMA phantom with engraved slots for keeping thermoluminescence dosemeters (TLD) has been developed. The radiation transmission property of the developed phantom was compared with the commercially available phantoms for verifying its suitability for mammography dosimetry. The breast entrance exposure (BEE), mean glandular dose (MGD), percentage depth dose (PDD), percentage surface dose distribution (PSDD), calibration testing of automatic exposure control (AEC) and density control function of a mammography machine were measured using this phantom. MGD was derived from the measured BEE following two different methodologies and the results were compared. The PDD and PSDD measurements were carried out using LiF: Mg, Cu, P chips. The in-house phantom was found comparable with the commercially available phantoms. The difference in the MGD values derived using two different methods were found in the range of 17.5-32.6 %. Measured depth ranges in the phantom lie between 0.32 and 0.40 cm for 75 % depth dose, 0.73 and 0.92 cm for 50 % depth dose, and 1.54 and 1.78 cm for 25 % depth dose. Higher PSDD value was observed towards chest wall edge side of the phantom, which is due to the orientation of cathode-anode axis along the chest wall to the nipple direction. Results obtained for AEC configuration testing shows that the observed mean optical density (O.D) of the phantom image was 1.59 and O.D difference for every successive increase in thickness of the phantom was within ±0.15 O.D. Under density control function testing, at -2 and -1 density settings, the variation in film image O.D was within ±0.15 O.D of the normal density

  15. Experimental Setup for Determining Ammonia-Salt Adsorption and Desorption Behavior Under Typical Heat Pump Conditions. Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Van der Pal, M.; De Boer, R.; Veldhuis, J.B.J. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2013-09-15

    For the aim of obtaining a better understanding of the performance of a salt-ammonia sorption reactor/heat exchanger a new test-rig was developed. This test-rig enables the measurement of the performance in adsorption and desorption mode of different sorption reactor designs. It measures the speed of uptake and release of ammonia gas of various salt-ammonia reactions under well-controlled and well-monitored process conditions, similar to the heat pump conditions. The test-rig measures the ammonia uptake and release under controlled pressure and temperature conditions. Temperatures of the salt reactor can be varied from ambient temperature up to 200{sup o}C and the ammonia pressure can be varied between 0.02 to 2 MPa. These conditions can be set independently and repeated at regular time-intervals. Besides NH3-mass-flow meters, pressure and temperature sensors, the setup also contains an endoscope to observe any macroscopic structural changes in the material during uptake and release of ammonia. Measurements so far have shown a liquid phase of LiCl.3NH3 at pressures of 0.5 MPa and temperatures exceeding 90{sup o}C. Voilent foaming is observed at 120{sup o}C resulting in salt losses. A correlation was determined between the reaction rate of MgCl{sub 2}(2-6)NH3 and the relative pressure gradient yielding a reaction time of about 1500 seconds for a relative pressure difference of 1. Multiple sorption cycles of the CaCl{sub 2}(2-4)NH3 reaction, showed a reduced activity from 85% of the theoretical maximum sorbed mass at the first sorption cycle, to 15% after 300+ cycles.

  16. Doses mammography: from phantom to the patient

    Energy Technology Data Exchange (ETDEWEB)

    Cross, P [Gammasonic Radiological Services, Pty., Ltd., Five Dock, NSW (Australia)

    1994-02-01

    While the use of a reference phantom is essential for dosimetry in acceptance testing and in regular quality control checks of a mammographic X-ray unit, it is also of importance to be able to estimate the patient dose in each individual investigation. Radiographic and physical data were analysed for a total of 212 women who were screened at three locations participating in a breast screening programme. The radiologists made estimates of the individual breast composition (%glandular/adipose ratio) at the film reporting sessions, and then the glandular doses were calculated by the auditor according to the NCRP 85 methodology. Arising from the data analysis of this dosimetry survey, a method is proposed to determine objectively patient breast composition from the photo-timed mAs for a given film optical density setting. This permits the NCRP calculations to be extended from breasts of 'average' (50/50) composition to breasts of individually determined composition. The diversity of the results between the three locations emphasises the need for regular audits of a mammographic X-ray unit's performance by an experienced radiological physicists, at least annually or after any major interventional service on the unit. 11 refs., 6 tabs., 4 figs.

  17. WE-F-16A-06: Using 3D Printers to Create Complex Phantoms for Dose Verification, Quality Assurance, and Treatment Planning System Commissioning in Radiotherapy

    International Nuclear Information System (INIS)

    Kassaee, A; Ding, X; McDonough, J; Reiche, M; Witztum, A; Teo, B

    2014-01-01

    Purpose: To use 3D printers to design and construct complex geometrical phantoms for commissioning treatment planning systems, dose calculation algorithms, quality assurance (QA), dose delivery, and patient dose verifications. Methods: In radiotherapy, complex geometrical phantoms are often required for dose verification, dose delivery and calculation algorithm validation. Presently, fabrication of customized phantoms is limited due to time, expense and challenges in machining of complex shapes. In this work, we designed and utilized 3D printers to fabricate two phantoms for QA purposes. One phantom includes hills and valleys (HV) for verification of intensity modulated radiotherapy for photons, and protons (IMRT and IMPT). The other phantom includes cylindrical cavities (CC) of various sizes for dose verification of inhomogeneities. We evaluated the HV phantoms for an IMPT beam, and the CC phantom to study various inhomogeneity configurations using photon, electron, and proton beams. Gafcromic ™ films were used to quantify the dose distributions delivered to the phantoms. Results: The HV phantom has dimensions of 12 cm × 12 cm and consists of one row and one column of five peaks with heights ranging from 2 to 5 cm. The CC phantom has a size 10 cm × 14 cm and includes 6 cylindrical cavities with length of 7.2 cm and diameters ranging from 0.6 to 1.2 cm. The IMPT evaluation using the HV phantom shows good agreement as compared to the dose distribution calculated with treatment planning system. The CC phantom also shows reasonable agreements for using different algorithms for each beam modalities. Conclusion: 3D printers with submillimiter resolutions are capable of printing complex phantoms for dose verification and QA in radiotherapy. As printing costs decrease and the technology becomes widely available, phantom design and construction will be readily available to any clinic for testing geometries that were not previously feasible

  18. Characterization of a dielectric phantom for high-field magnetic resonance imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Qi, E-mail: Qi.Duan@nih.gov; Duyn, Jeff H.; Gudino, Natalia; Zwart, Jacco A. de; Gelderen, Peter van [Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892 (United States); Sodickson, Daniel K.; Brown, Ryan [The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016 (United States)

    2014-10-15

    Purpose: In this work, a generic recipe for an inexpensive and nontoxic phantom was developed within a range of biologically relevant dielectric properties from 150 MHz to 4.5 GHz. Methods: The recipe includes deionized water as the solvent, NaCl to primarily control conductivity, sucrose to primarily control permittivity, agar–agar to gel the solution and reduce heat diffusivity, and benzoic acid to preserve the gel. Two hundred and seventeen samples were prepared to cover the feasible range of NaCl and sucrose concentrations. Their dielectric properties were measured using a commercial dielectric probe and were fitted to a 3D polynomial to generate a recipe describing the properties as a function of NaCl concentration, sucrose concentration, and frequency. Results: Results indicated that the intuitive linear and independent relationships between NaCl and conductivity and between sucrose and permittivity are not valid. A generic polynomial recipe was developed to characterize the complex relationship between the solutes and the resulting dielectric values and has been made publicly available as a web application. In representative mixtures developed to mimic brain and muscle tissue, less than 2% difference was observed between the predicted and measured conductivity and permittivity values. Conclusions: It is expected that the recipe will be useful for generating dielectric phantoms for general magnetic resonance imaging (MRI) coil development at high magnetic field strength, including coil safety evaluation as well as pulse sequence evaluation (including B{sub 1}{sup +} mapping, B{sub 1}{sup +} shimming, and selective excitation pulse design), and other non-MRI applications which require biologically equivalent dielectric properties.

  19. Effect of phantom dimension variation on Monte Carlo simulation speed and precision

    International Nuclear Information System (INIS)

    Lin Hui; Xu Yuanying; Xu Liangfeng; Li Guoli; Jiang Jia

    2007-01-01

    There is a correlation between Monte Carlo simulation speed and the phantom dimension. The effect of the phantom dimension on the Monte Carlo simulation speed and precision was studied based on a fast Monte Carlo code DPM. The results showed that when the thickness of the phantom was reduced, the efficiency would increase exponentially without compromise of its precision except for the position at the tailor. When the width of the phantom was reduced to outside the penumbra, the effect on the efficiency would be neglectable. However when it was reduced to within the penumbra, the efficiency would be increased at some extent without precision loss. This result was applied to a clinic head case, and the remarkable increased efficiency was acquired. (authors)

  20. Complexity of MRI induced heating on metallic leads: Experimental measurements of 374 configurations

    Directory of Open Access Journals (Sweden)

    Mendoza Gonzalo

    2008-03-01

    Full Text Available Abstract Background MRI induced heating on PM leads is a very complex issue. The widely varying results described in literature suggest that there are many factors that influence the degree of heating and that not always are adequately addressed by existing testing methods. Methods We present a wide database of experimental measurements of the heating of metallic wires and PM leads in a 1.5 T RF coil. The aim of these measurements is to systematically quantify the contribution of some potential factors involved in the MRI induced heating: the length and the geometric structure of the lead; the implant location within the body and the lead path; the shape of the phantom used to simulate the human trunk and its relative position inside the RF coil. Results We found that the several factors are the primary influence on heating at the tip. Closer locations of the leads to the edge of the phantom and to the edge of the coil produce maximum heating. The lead length is the other crucial factor, whereas the implant area does not seem to have a major role in the induced temperature increase. Also the lead structure and the geometry of the phantom revealed to be elements that can significantly modify the amount of heating. Conclusion Our findings highlight the factors that have significant effects on MRI induced heating of implanted wires and leads. These factors must be taken into account by those who plan to study or model MRI heating of implants. Also our data should help those who wish to develop guidelines for defining safe medical implants for MRI patients. In addition, our database of the entire set of measurements can help those who wish to validate their numerical models of implants that may be exposed to MRI systems.

  1. Full-scale and time-scale heating experiments at Stripa: preliminary results. Technical project report No. 11

    International Nuclear Information System (INIS)

    Cook, N.G.W.; Hood, M.

    1978-12-01

    Two full-scale heating experiments and a time-scale heating experiment have recently been started in granite 340 meters below surface. The purpose of the full-scale heating experiments is to assess the near-field effects of thermal loading for the design of an underground repository of nuclear wastes. That of the time-scale heating experiments is to obtain field data of the interaction between heaters and its effect on the rock mass during a period of about two years, which corresponds to about twenty years of full-scale operation. Geological features of the rock around each experiment have been mapped carefully, and temperatures, stresses and displacements induced in the rock by heating have been calculated in advance of the experiments. Some 800 different measurements are recorded at frequent intervals by a computer system situated underground. These data can be compared at any time with predictions made earlier on video display units underground

  2. 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

  3. Experimental results of 2-propanol dehydrogenation with a falling-liquid film reactor for solar chemical heat pump; Solar chemical heat pump ni okeru ryuka ekimakushiki 2-propanol bunkai hanno jikken

    Energy Technology Data Exchange (ETDEWEB)

    Doi, T; Tanaka, T; Ando, Y; Takashima, T [Electrotechnical Laboratory, Tsukuba (Japan); Koike, M; Kamoshida, J [Shibaura Institute of Technology, Tokyo (Japan)

    1997-11-25

    A solar chemical heat pump is intended to attempt multi-purposed effective utilization of solar energy by raising low temperature solar heat of about 100 degC to 150 to 200 degC by utilizing chemical reactions. The chemical heat pump under the present study uses a 2-propanol (IPA)/acetone/hydrogen system which can utilize low-temperature solar heat and has large temperature rising degree. It was found from the result of experiments and analyses that IPA dehydrogenation reaction can improve more largely the heat utilization rate in using a falling-liquid film reactor than using a liquid phase suspended system. As an attempt to improve further the heat utilization rate, this paper reports the result of experimental discussions on inclination angles of a reaction vessel and feed liquid flow rate which would affect the fluid condition of the liquid film. As a result of the experiments, the initial deterioration in the catalyst has settled in about 15 hours, and its activity has decreased to about 60% of the initial activity. It was made clear that the influence of the inclination angle of the reaction vessel on the reaction is small. 5 refs., 7 figs.

  4. 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

  5. Tissue Equivalent Phantom Design for Characterization of a Coherent Scatter X-ray Imaging System

    Science.gov (United States)

    Albanese, Kathryn Elizabeth

    testing. Our imaging system has been able to define the location and composition of the various materials in the phantom. These phantoms were used to characterize the CACSSI system in terms of beam width and imaging technique. The result of this work showed accurate modeling and characterization of the phantoms through comparison of the tissue-equivalent form factors to those from literature. The physical construction of the phantoms, based on actual patient anatomy, was validated using mammography and computed tomography to visually compare the clinical images to those of actual patient anatomy.

  6. The development of a population of 4D pediatric XCAT phantoms for imaging research and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Segars, W. P., E-mail: paul.segars@duke.edu; Norris, Hannah; Sturgeon, Gregory M.; Zhang, Yakun; Bond, Jason; Samei, E. [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 27705 (United States); Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2015-08-15

    Purpose: We previously developed a set of highly detailed 4D reference pediatric extended cardiac-torso (XCAT) phantoms at ages of newborn, 1, 5, 10, and 15 yr with organ and tissue masses matched to ICRP Publication 89 values. In this work, we extended this reference set to a series of 64 pediatric phantoms of varying age and height and body mass percentiles representative of the public at large. The models will provide a library of pediatric phantoms for optimizing pediatric imaging protocols. Methods: High resolution positron emission tomography-computed tomography data obtained from the Duke University database were reviewed by a practicing experienced radiologist for anatomic regularity. The CT portion of the data was then segmented with manual and semiautomatic methods to form a target model defined using nonuniform rational B-spline surfaces. A multichannel large deformation diffeomorphic metric mapping algorithm was used to calculate the transform from the best age matching pediatric XCAT reference phantom to the patient target. The transform was used to complete the target, filling in the nonsegmented structures and defining models for the cardiac and respiratory motions. The complete phantoms, consisting of thousands of structures, were then manually inspected for anatomical accuracy. The mass for each major tissue was calculated and compared to linearly interpolated ICRP values for different ages. Results: Sixty four new pediatric phantoms were created in this manner. Each model contains the same level of detail as the original XCAT reference phantoms and also includes parameterized models for the cardiac and respiratory motions. For the phantoms that were 10 yr old and younger, we included both sets of reproductive organs. This gave them the capability to simulate both male and female anatomy. With this, the population can be expanded to 92. Wide anatomical variation was clearly seen amongst the phantom models, both in organ shape and size, even for

  7. 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)

  8. 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)

  9. Cosmological perturbations in transient phantom inflation scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Richarte, Martin G. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil); Universidad de Buenos Aires, Ciudad Universitaria 1428, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Kremer, Gilberto M. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil)

    2017-01-15

    We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that the present unified model only deals with a single field and that the transition between the two eras is achieved in a smooth way, so the model does not suffer from the eternal inflation issue. We explore the conditions for the crossing of the phantom divide line within the inflationary era along with the structural stability of several critical points. We study the behavior of the phantom field within the slow-climb approximation along with the necessary conditions to have sufficient inflation. We also examine the model at the level of classical perturbations within the Newtonian gauge and determine the behavior of the gravitational potential, contrast density and perturbed field near the inflation stage and the subsequent radiation era. (orig.)

  10. 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

  11. 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

  12. Transport calculations for a 14.8 MeV neutron beam in a water phantom

    International Nuclear Information System (INIS)

    Goetsch, S.J.

    1981-01-01

    A coupled neutron/photon Monte Carlo radiation transport code (MORSE-CG) has been used to calculate neutron and photon doses in a water phantom irradiated by 14.8 MeV neutrons from the Gas Target Neutron Source. The source-collimator-phantom geometry was carefully simulated. Results of calculations utilizing two different statistical estimators (next-collision and track-length) are presented

  13. Development of an Anthropomorphic Breast Phantom for Combined PET, B-Mode Ultrasound and Elastographic Imaging

    OpenAIRE

    Dang, J; Lecoq, P; Tavernier, S; Lasaygues, P; Mensah, S; Zhang, D C; Auffray, E; Frisch, B; Varela, J; Wan, M X; Felix, N

    2011-01-01

    International audience; Combining the advantages of different imaging modalities leads to improved clinical results. For example, ultrasound provides good real-time structural information without any radiation and PET provides sensitive functional information. For the ongoing ClearPEM-Sonic project combining ultrasound and PET for breast imaging, we developed a dual-modality PET/Ultrasound (US) phantom. The phantom reproduces the acoustic and elastic properties of human breast tissue and allo...

  14. Noncontact ultrasound imaging applied to cortical bone phantoms.

    Science.gov (United States)

    Bulman, J B; Ganezer, K S; Halcrow, P W; Neeson, Ian

    2012-06-01

    The purpose of this paper was to take the first steps toward applying noncontact ultrasound (NCU) to the tasks of monitoring osteoporosis and quantitative ultrasound imaging (QUS) of cortical bone. The authors also focused on the advantages of NCU, such as its lack of reliance on a technologist to apply transducers and a layer of acoustical coupling gel, the ability of the transducers to operate autonomously as specified by preprogrammed software, and the likely reduction in statistical and systematic errors associated with the variability in the pressure applied by the clinician to the transmitting transducer that NCU might provide. The authors also undertook this study in order to find additional applications of NCU beyond its past limited usage in assessing the severity of third degree burns. A noncontact ultrasound imaging system using a pair of specially designed broadband, 1.5 MHz noncontact piezoelectric transducers and cortical bone phantoms, were used to determine bone mineral density (BMD), speed of sound (SOS), integrated response (IR), and ultrasonic transmittance. Air gaps of greater than 3 cm, two transmission and two reflection paths, and a digital signal processor were also used in the collection of data from phantoms of nominal mass densities that varied from 1.17 to 2.25 g/cm(3) and in bone mineral density from 0 to 1.7 g/cm(3). Good correlations between known BMD and measured SOS, IR, and transmittance were obtained for all 17 phantoms, and methods for quantifying and minimizing sources of systematic errors were outlined. The BMD of the phantom sets extended through most of the in vivo range found in cortical bone. A total of 16-20 repeated measurements of the SOS, thickness, and IR for the phantom set that were conducted over a period of several months showed a small variation in the range of measurements of ±1%-2%. These NCU data were shown to be in agreement with similar results using contact ultrasound to be within 1%-2%. Transmittance

  15. New mechanism to cross the phantom divide

    OpenAIRE

    Du, Yunshuang; Zhang, Hongsheng; Li, Xin-Zhou

    2010-01-01

    Recently, type Ia supernovae data appear to support a dark energy whose equation of state $w$ crosses -1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the equation of state to cross the phantom divide by a scalar field in the gravity with an additional inverse power-law term of Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the phantom divide is obtained. So...

  16. Results of studying of turbulent heat transfer deterioration and their application for development of engineering methods of calculation of heat transfer and pressure drop in supercritical-pressure coolant flow

    International Nuclear Information System (INIS)

    Vladimir A Kurganov; Yuri A Zeigarnik

    2005-01-01

    Full text of publication follows: Using of the supercritical-pressure (SCP) water as a working medium is an apparent way to increase specific capacity and economic efficiency of nuclear power installations. Nevertheless, to provide safe operation of SCP nuclear power units, it is necessary to considerably improve reliability and accuracy of calculations of pressure drop and heat transfer in the SCP working media and coolants flows and the methods of forecasting such a dangerous phenomenon as deterioration of the turbulent heat transfer at a certain level of heat flux density. A value of the latter changes within a very large range depending on the specific conditions of the process under consideration. In the paper, the main results of the experimental study of heat transfer, pressure drop, and velocity and temperature fields in both upward and downward flows of the SCP CO 2 in tubes are considered. This study was conducted at OIVT RAN under conditions of heat input and embraced the regimes of normal and deteriorated heat transfer as well. On the basis of this data, the concept regarding to physical mechanism of incipience of the regimes of deteriorated heat transfer was developed. Classification of different modes of heat transfer deterioration in vertical channels is proposed. A degree of a danger of certain regimes is assessed. It is shown that the above phenomenon is caused by transformation of the structure of nonisothermal flow of SCP fluid due to changes in proportions between the forces acting upon a flow, specifically, because of an increase in the inertia forces due to thermal acceleration of a flow and/or in Archimedes' (buoyancy) forces up to the level comparable or higher than that of friction forces. The efficiency of the most thorough correlations for calculating normal and deteriorated heat transfer in flows of SCP water and CO 2 is analyzed. Reliability of existed recommendations to determine boundaries of normal heat transfer regimes is considered

  17. Image quality assessment using the CD-DISC phantom for vascular radiology and vascular surgery

    International Nuclear Information System (INIS)

    Struelens, Lara; Hambach, Lionel; Buls, Nico; Smans, Kristien; Malchair, Francoise; Hoornaert, Marie-Therese; Vanhavere, Filip; Bosmans, Hilde

    2008-01-01

    The purpose of the study was to evaluate image quality (IQ) associated with vascular radiology and vascular surgery procedures in Belgium and to determine reference values for future image quality assessment. IQ was evaluated with the CD-DISC contrast-detail phantom. This circular PMMA phantom contains 225 holes with different diameter and depth, to quantify resolution and contrast. Images of the phantom were acquired for both fluoroscopy and subtraction images on 21 systems. Three observers evaluated the images by determining the threshold contrast visible for every diameter. This results in contrast-detail curves and image quality figures. We observed a large difference in IQ between the centres. No straightforward correlation could be found with radiation dose or other exposure settings. A comparison was made with the image quality evaluation of the systems performed with the TOR[18FG] phantom for fluoroscopy. There is no clear correlation observed between the results of the CD-DISC phantom and the TOR phantom. However, systems with very poor or very good image quality could be detected by both phantoms. An important result is that a 75th percentile reference contrast-detail curve could be proposed to separate the best centres from these with poorer quality. Some centres had also a significantly better image quality than others. Therefore, we introduced also a 25th percentile. Centres with IQ above this value are recommended to lower the dose and work with acceptable rather than excellent image quality. The CD-DISC phantom thus allows to guide the image quality setting

  18. Heat transfer

    International Nuclear Information System (INIS)

    Saad, M.A.

    1985-01-01

    Heat transfer takes place between material systems as a result of a temperature difference. The transmission process involves energy conversions governed by the first and second laws of thermodynamics. The heat transfer proceeds from a high-temperature region to a low-temperature region, and because of the finite thermal potential, there is an increase in entropy. Thermodynamics, however, is concerned with equilibrium states, which includes thermal equilibrium, irrespective of the time necessary to attain these equilibrium states. But heat transfer is a result of thermal nonequilibrium conditions, therefore, the laws of thermodynamics alone cannot describe completely the heat transfer process. In practice, most engineering problems are concerned with the rate of heat transfer rather than the quantity of heat being transferred. Resort then is directed to the particular laws governing the transfer of heat. There are three distinct modes of heat transfer: conduction, convection, and radiation. Although these modes are discussed separately, all three types may occur simultaneously

  19. Characteristics of 3D gamma evaluation according to phantom rotation error and dose gradient

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyeong Hyun; Kim, Dong Su; Kim, Tae Ho; Kang, Seong Hee; Shin, Dong Seok; Noh, Yu Yoon; Suh, Tae Seok [Dept. of Biomedical Engineering, Research Institute of Biomedical Engineering, College of Medicine, the Catholic University of Korea, Seoul (Korea, Republic of); Cho, Min Seok [Dept. of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of)

    2016-12-15

    In intensity modulated radiation therapy (IMRT) quality assurance (QA) using dosimetric phantom, a spatial uncertainty induced from phantom set-up inevitably occurs and gamma index that is used to evaluate IMRT plan quality can be affected differently by a combination of the spatial uncertainty and magnitude of dose gradient. In this study, we investigated the impacts of dose gradient and the phantom set-up error on 3D gamma evaluation. In this study, we investigated the characteristics of gamma evaluation according to dose gradient and phantom rotation axis. As a result, 3D gamma had better performance than 2D gamma. Therefore, it can be useful for IMRT QA analysis at clinical field.

  20. Calibration of lung counter using a CT model of Torso phantom and Monte Carlo method

    International Nuclear Information System (INIS)

    Zhang Binquan; Ma Jizeng; Yang Duanjie; Liu Liye; Cheng Jianping

    2006-01-01

    Tomography image of a Torso phantom was obtained from CT-Scan. The Torso phantom represents the trunk of an adult man that is 170 cm high and weight of 65 kg. After these images were segmented, cropped, and resized, a 3-dimension voxel phantom was created. The voxel phantom includes more than 2 million voxels, which size was 2.73 mm x 2.73 mm x 3 mm. This model could be used for the calibration of lung counter with Monte Carlo method. On the assumption that radioactive material was homogeneously distributed throughout the lung, counting efficiencies of a HPGe detector in different positions were calculated as Adipose Mass fraction (AMF) was different in the soft tissue in chest. The results showed that counting efficiencies of the lung counter changed up to 67% for 17.5 keV γ ray and 20% for 25 keV γ ray when AMF changed from 0 to 40%. (authors)

  1. A new cubic phantom for PET/CT dosimetry: Experimental and Monte Carlo characterization

    International Nuclear Information System (INIS)

    Belinato, Walmir; Silva, Rogerio M.V.; Souza, Divanizia N.; Santos, William S.; Caldas, Linda V.E.; Perini, Ana P.; Neves, Lucio P.

    2015-01-01

    In recent years, positron emission tomography (PET) associated with multidetector computed tomography (MDCT) has become a diagnostic technique widely disseminated to evaluate various malignant tumors and other diseases. However, during PET/CT examinations, the doses of ionizing radiation experienced by the internal organs of patients may be substantial. To study the doses involved in PET/CT procedures, a new cubic phantom of overlapping acrylic plates was developed and characterized. This phantom has a deposit for the placement of the fluorine-18 fluoro-2-deoxy-D-glucose ( 18 F-FDG) solution. There are also small holes near the faces for the insertion of optically stimulated luminescence dosimeters (OSLD). The holes for OSLD are positioned at different distances from the 18 F-FDG deposit. The experimental results were obtained in two PET/CT devices operating with different parameters. Differences in the absorbed doses were observed in OSLD measurements due to the non-orthogonal positioning of the detectors inside the phantom. This phantom was also evaluated using Monte Carlo simulations, with the MCNPX code. The phantom and the geometrical characteristics of the equipment were carefully modeled in the MCNPX code, in order to develop a new methodology form comparison of experimental and simulated results, as well as to allow the characterization of PET/CT equipments in Monte Carlo simulations. All results showed good agreement, proving that this new phantom may be applied for these experiments. (authors)

  2. A new cubic phantom for PET/CT dosimetry: Experimental and Monte Carlo characterization

    Energy Technology Data Exchange (ETDEWEB)

    Belinato, Walmir [Departamento de Ensino, Instituto Federal de Educacao, Ciencia e Tecnologia da Bahia, Campus Vitoria da Conquista, Zabele, Av. Amazonas 3150, 45030-220 Vitoria da Conquista, BA (Brazil); Silva, Rogerio M.V.; Souza, Divanizia N. [Departamento de Fisica, Universidade Federal de Sergipe-UFS, Sao Cristovao, Sergipe (Brazil); Santos, William S.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, 05508-000 Sao Paulo SP (Brazil); Perini, Ana P.; Neves, Lucio P. [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, 05508-000 Sao Paulo SP (Brazil); Instituto de Fisica, Universidade Federal de Uberlandia, Caixa Postal 593, 38400-902, Uberlandia, MG (Brazil)

    2015-07-01

    In recent years, positron emission tomography (PET) associated with multidetector computed tomography (MDCT) has become a diagnostic technique widely disseminated to evaluate various malignant tumors and other diseases. However, during PET/CT examinations, the doses of ionizing radiation experienced by the internal organs of patients may be substantial. To study the doses involved in PET/CT procedures, a new cubic phantom of overlapping acrylic plates was developed and characterized. This phantom has a deposit for the placement of the fluorine-18 fluoro-2-deoxy-D-glucose ({sup 18}F-FDG) solution. There are also small holes near the faces for the insertion of optically stimulated luminescence dosimeters (OSLD). The holes for OSLD are positioned at different distances from the {sup 18}F-FDG deposit. The experimental results were obtained in two PET/CT devices operating with different parameters. Differences in the absorbed doses were observed in OSLD measurements due to the non-orthogonal positioning of the detectors inside the phantom. This phantom was also evaluated using Monte Carlo simulations, with the MCNPX code. The phantom and the geometrical characteristics of the equipment were carefully modeled in the MCNPX code, in order to develop a new methodology form comparison of experimental and simulated results, as well as to allow the characterization of PET/CT equipments in Monte Carlo simulations. All results showed good agreement, proving that this new phantom may be applied for these experiments. (authors)

  3. 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.

  4. Possible association between phantom vibration syndrome and occupational burnout

    Science.gov (United States)

    Chen, Chao-Pen; Wu, Chi-Cheng; Chang, Li-Ren; Lin, Yu-Hsuan

    2014-01-01

    Background Phantom vibration syndrome (PVS) and phantom ringing syndrome (PRS) occur in many cell phone users. Previous studies have indicated an association between PVS/PRS and job stress. The aim of this study was to determine if PVS/PRS were also associated with occupational burnout. Methods This was a cross-sectional study of 384 employees of a high-tech company in northern Taiwan. They all completed a phantom vibration and ringing questionnaire, the Hospital Anxiety and Depression Scale, and the Chinese version of the Occupational Burnout Inventory. Results Significantly more women and people with at least a college education were in the population with PRS and PVS, respectively. Anxiety and depression had no associations with PVS/PRS. Higher scores for personal fatigue, job fatigue, and service target fatigue had an independent impact on the presence of PVS, but only a higher score for service target fatigue had an independent impact on the presence of PRS. Conclusion The independent association between work-related burnout and PVS/PRS suggests that PVS/PRS may be a harbinger of mental stress or a component of the clinical burnout syndrome, and may even be a more convenient and accurate predictor of occupational burnout. PMID:25750984

  5. Membership function used to construction of a hand homogeneous phantom

    International Nuclear Information System (INIS)

    Pavan, Ana Luiza Menegatti; Alvarez, Matheus; Alves, Allan Felipe Fattori; Rosa, Maria Eugenia Dela; Miranda, Jose Ricardo de Arruda

    2014-01-01

    Fractures and dislocations of the hand are some injuries most frequently encountered in trauma of the musculoskeletal system. In evaluating these lesions, in addition to physical examination, radiography, in at least two incidents, is the investigation of choice, and rarely is necessary the help of other images to establish the diagnosis and treatment. The image quality of X-ray examination is therefore essential. In this study, a homogeneous phantom hand was developed to be used in the optimization of images from hand using computed radiography system process. In this procedure were quantified thicknesses of different tissues that constitute an anthropomorphic phantom hand. To perform the classification and quantification of tissue was applied membership functions for histograms of CT scans. The same procedure was adopted for retrospective examinations of 30 patients of the Hospital das Clinicas, Botucatu Medicine School, UNESP (HCFMB-UNESP). The results showed agreement between the thicknesses of tissues that make up the anthropomorphic phantom and sampling of patients, presenting variations between 12.63% and 6.48% for soft tissue and bone, respectively. (author)

  6. A phantom study of tumor contouring on PET imaging

    International Nuclear Information System (INIS)

    Chen Song; Li Xuena; Li Yaming; Yin Yafu; Li Na; Han Chunqi

    2010-01-01

    Objective: To explore an algorithm to define the threshold value for tumor contouring on 18 F-fluorodeoxyglucose (FDG) PET imaging. Methods: A National Electrical Manufacturing Association (NEMA)NU 2 1994 PET phantom with 5 spheres of different diameters were filled with 18 F-FDG. Seven different sphere-to-background ratios were obtained and the phantom was scanned by Discovery LS 4. For each sphere-to-background ratio, the maximum standardized uptake value (SUV max ) of each sphere, the SUV of the border of each sphere (SUV border ), the mean SUV of a 1 cm region of background (SUV bg ) and the diameter (D) of each sphere were measured. SPSS 13.0 software was used for curve fitting and regression analysis to obtain the threshold algorithm. The calculated thresholds were applied to delineate 29 pathologically confirmed lung cancer lesions on PET images and the obtained volumes were compared with the volumes contoured on CT images in lung window. Results: The algorithm for defining contour threshold is TH% = 33.1% + 46.8% SUV bg /SUV max + 13.9%/D (r = 0.994) by phantom studies. For 29 lung cancer lesions, the average gross tumor volumes (GTV) delineated on PET and CT are (7.36±1.62) ml and (8.31±2.05) ml, respectively (t = -1.26, P>0.05). Conclusion: The proposed threshold algorithm for tumor contouring on PET image could provide comparable GTV with CT. (authors)

  7. Calibration of clinical dosemeters in the IAEA water phantom

    International Nuclear Information System (INIS)

    Caldas, L.V.E.; Albuquerque, M.P.P.

    1994-01-01

    The procedures recommended by the IAEA Code of Practice were applied at the Calibration Laboratory of Sao Paulo in order to provide in the future the clinical dosemeters users with absorbed dose to water calibration factors for Cobalt 60 radiation beams. In this work the clinical dosemeters were calibrated free in air and in water, and the results were compared, using conversion factors. The several tested clinical dosemeters of different manufacturers and models belong to the laboratory and to hospitals. For the measurements in water the IAEA cubic water phantom was used. The dosemeters were all calibrated free in air in terms of air kerma, and the calibration factors in terms of absorbed dose to water were obtained through conversion factors. the same dosemeters were also calibrated into the water phantom. Good agreement was found between the two methods, the differences were always less than 0.5%. The data obtained during this work show that when the dosemeters are used only in Cobalt 60 radiation and the users apply in the hospital routine work the IAEA Code of Practice, the calibration can be performed directly in the water phantom. This procedure provides the useful calibration factors in terms of absorbed dose to water

  8. Results of experimental investigations on the heat conductivity of nanofluids based on diathermic oil for high temperature applications

    International Nuclear Information System (INIS)

    Colangelo, Gianpiero; Favale, Ernani; Risi, Arturo de; Laforgia, Domenico

    2012-01-01

    Highlights: ► This work reports experimental results for nanofluids using diathermic oil as base fluid. ► Nanofluids with CuO, Al 2 O 3 , ZnO and Cu, with different shapes and concentrations have been tested. ► Thermal conductivity enhancement of nanofluids with diathermic oil is higher than those with demineralized water. ► Better results were obtained with ZnO, for nanofluids with metal oxide nanoparticles. -- Abstract: The work reported in this paper shows the experimental results from a study on diathermic oil based nanofluids. Diathermic oil finds application in renewable energy, cogeneration and cooling systems. For example, it is used in solar thermodynamic or biomass plants, where high efficiency, compact volumes and high energy fluxes are required. Besides diathermic oil is very important in those applications where high temperatures are reached or where the use of water or vapor is not suitable. Therefore an improvement of diathermic oil thermo-physical properties, by using of nanoparticles, can increase the performance of the systems. In literature there are not many experimental data on diathermic oil based nanofluids because many experimental campaigns are focused on water nanofluids. Samples of nanofluids, with nanoparticles of CuO, Al 2 O 3 , ZnO and Cu, having different shapes and concentrations varying from 0.0% up to 3.0%, have been produced and their thermal conductivity has been measured by means of hot-wire technique, according to the standard ASTM D 2717-95. Measurements were carried out to investigate the effects of volume fraction, particle size of nanoparticles on the thermal conductivity of the nanofluid. The effect of temperature has been also investigated in the range 20–60 °C. A dependence was observed on the measured parameters and the results showed that the heat transfer performance of diathermic oil enhances more than water with the same nanoparticles.

  9. Development of the voxel computational phantoms of pediatric patients and their application to organ dose assessment

    Science.gov (United States)

    Lee, Choonik

    A series of realistic voxel computational phantoms of pediatric patients were developed and then used for the radiation risk assessment for various exposure scenarios. The high-resolution computed tomographic images of live patients were utilized for the development of the five voxel phantoms of pediatric patients, 9-month male, 4-year female, 8-year female, 11-year male, and 14-year male. The phantoms were first developed as head and torso phantoms and then extended into whole body phantoms by utilizing computed tomographic images of a healthy adult volunteer. The whole body phantom series was modified to have the same anthropometrics with the most recent reference data reported by the international commission on radiological protection. The phantoms, named as the University of Florida series B, are the first complete set of the pediatric voxel phantoms having reference organ masses and total heights. As part of the dosimetry study, the investigation on skeletal tissue dosimetry methods was performed for better understanding of the radiation dose to the active bone marrow and bone endosteum. All of the currently available methodologies were inter-compared and benchmarked with the paired-image radiation transport model. The dosimetric characteristics of the phantoms were investigated by using Monte Carlo simulation of the broad parallel beams of external phantom in anterior-posterior, posterior-anterior, left lateral, right lateral, rotational, and isotropic angles. Organ dose conversion coefficients were calculated for extensive photon energies and compared with the conventional stylized pediatric phantoms of Oak Ridge National Laboratory. The multi-slice helical computed tomography exams were simulated using Monte Carlo simulation code for various exams protocols, head, chest, abdomen, pelvis, and chest-abdomen-pelvis studies. Results have found realistic estimates of the effective doses for frequently used protocols in pediatric radiology. The results were very

  10. About calculation results of heat transfer in the fuel assembly clusters cooled by water with supercritical parameters

    International Nuclear Information System (INIS)

    Grabezhnaya, V.A.

    2008-01-01

    Paper reviews the numerical investigation into the heat transfer in the supercritical water cooled fuel assemblies on the basis of the various commercial codes. The turbulence available models specified in the codes describe adequately the experimental data in tubes within the range of flow temperatures away from the pseudocritical point, as well as under high mass velocities. There are k-ε type turbulence models that show qualitatively the local acceleration (slowdown) of the heat transfer in tubes, but they fail to describe the mentioned phenomena quantitatively. To determine the effect of grid spacers on the suppression of the heat transfer local slowdown and on the heat transfer acceleration in fuel assemblies and to ensure more accurate calculation of the fuel element cladding maximum temperature one should perform a number of the experiments making use of the fuel assembly models [ru

  11. 30 kV/10 mA solid state anode modulator for gyrotron plasma heating: design issues and results

    International Nuclear Information System (INIS)

    Fasel, D.; Lucia, C.; Ganuza, D.; Doyharzabal, I.

    2001-01-01

    Three 30 kV/10 mA solid state pulsed modulators have been delivered to the CRPP in Lausanne, by the company JEMA. Each modulator supplies the anode grid of a triode type gyrotron, used for heating purpose at the third harmonic in the TCV Tokamak. The main parameters of the final design are: the use of solid state technology, a floating output referred to the -80 kV of the gyrotron cathode potential, an output voltage range of -5 to 30 kV, 1 kHz square and sinusoidal modulation, fast switching off to -5 kV (10 μs) and pulsed operation (duty cycle of 1%). After studying and testing a solution based on regulated Mosfet transistors in series, a more stable alternative has been adopted. The final topology consists of a rectifier fed from an insulated 230 V input, a chopper, two inverter steps (for +30 and -5 kV) supplying two diode rectifiers bridges through HV transformers with two switches which commute the load to the positive or negative voltage, connected in series. This article presents the most significant aspects of the design, with special emphasis on the control principle. The final results will be presented in the context of normal operation, supplying a triode gyrotron

  12. Impact of the temperature gradient between twin inclined jets and an oncoming crossflow on their resulting heat transfer

    International Nuclear Information System (INIS)

    Radhouane, Amina; Mahjoub, Nejla; Mhiri, Hatem; Le Palec, George; Bournot, Philippe

    2009-01-01

    This paper deals with the interaction of twin inclined jets in crossflow. The consideration of this particular configuration is of great interest due to its wide presence in various domains and applications and to its dependence in many parameters. These parameters may be geometric like the jets height, the jet nozzles separating distance, the jet nozzles, exit section, etc... It may also be based upon one of the reigning features like the velocity ratio, the temperature gradient, etc...The gradient between the jets and the crossflow temperatures is precisely the parameter we intend to handle in the present work due to its great relevance in several environmental concerns and in technical constraints as well. The evaluation of this parameter will be carried out numerically on the temperature distribution itself. This evaluation is likely to give a thorough idea about the cooling/heating process resulted from the jets interaction with the oncoming crossflow. Such an understanding is likely to give viable solutions to problems raised by this configuration like the acid rain engendered by too hot fumes or the deterioration of the combustors walls by too high temperature jets, etc...The numerically simulated model is based on the resolution of the Navier-Stokes equations by means of the finite volume method and the RSM second order turbulent model and is validated by confrontation to experimental data depicted on the same geometric replica

  13. Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

    Energy Technology Data Exchange (ETDEWEB)

    King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.; Browne, Jacinta E. [Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8 (Ireland); Centre for Advanced Medical Imaging (CAMI), St James' s Hospital, Dublin 8 (Ireland); Department of Medical Physics, University of Edinburgh, Edinburgh EH16 4TJ (United Kingdom); Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8 (Ireland)

    2011-02-15

    Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T{sub 1},T{sub 2}) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast

  14. Analysis of biological tissues in infant chest for the development of an equivalent radiographic phantom

    International Nuclear Information System (INIS)

    Pina, D. R.; Souza, Rafael T. F.; Duarte, Sergio B.; Alvarez, Matheus; Miranda, Jose R. A.

    2012-01-01

    Purpose: The main purpose of the present study was to determine the amounts of different tissues in the chest of the newborn patient (age ≤1 year), with the aim of developing a homogeneous phantom chest equivalent. This type of phantom is indispensable in the development of optimization procedures for radiographic techniques, including dosimetric control, which is a crucial aspect of pediatric radiology. The authors present a systematic set of procedures, including a computational algorithm, to estimate the amounts of tissues and thicknesses of the corresponding simulator material plates used to construct the phantom. Methods: The Gaussian fit of computed tomographic (CT) analysis was applied to classify and quantify different biological tissues. The methodology is summarized with a computational algorithm, which was used to quantify tissues through automated CT analysis. The thicknesses of the equivalent homogeneous simulator material plates were determined to construct the phantom. Results: A total of 180 retrospective CT examinations with anterior-posterior diameter values ranging 8.5-13.0 cm were examined. The amounts of different tissues were evaluated. The results provided elements to construct a phantom to simulate the infant chest in the posterior-anterior or anterior-posterior (PA/AP) view. Conclusions: To our knowledge, this report represents the first demonstration of an infant chest phantom dedicated to the radiology of children younger than one year. This phantom is a key element in the development of clinical charts for optimizing radiographic technique in pediatric patients. Optimization procedures for nonstandard patients were reported previously [Pina et al., Phys. Med. Biol. 49, N215-N226 (2004) and Pina et al., Appl. Radiat. Isot. 67, 61-69 (2009)]. The constructed phantom represents a starting point to obtain radiologic protocols for the infant patient.

  15. Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

    International Nuclear Information System (INIS)

    King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.; Browne, Jacinta E.

    2011-01-01

    Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T 1 ,T 2 ) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast to allow

  16. MCNPX simulation of proton dose distribution in homogeneous and CT phantoms

    International Nuclear Information System (INIS)

    Lee, C.C.; Lee, Y.J.; Tung, C.J.; Cheng, H.W.; Chao, T.C.

    2014-01-01

    A dose simulation system was constructed based on the MCNPX Monte Carlo package to simulate proton dose distribution in homogeneous and CT phantoms. Conversion from Hounsfield unit of a patient CT image set to material information necessary for Monte Carlo simulation is based on Schneider's approach. In order to validate this simulation system, inter-comparison of depth dose distributions among those obtained from the MCNPX, GEANT4 and FLUKA codes for a 160 MeV monoenergetic proton beam incident normally on the surface of a homogeneous water phantom was performed. For dose validation within the CT phantom, direct comparison with measurement is infeasible. Instead, this study took the approach to indirectly compare the 50% ranges (R 50% ) along the central axis by our system to the NIST CSDA ranges for beams with 160 and 115 MeV energies. Comparison result within the homogeneous phantom shows good agreement. Differences of simulated R 50% among the three codes are less than 1 mm. For results within the CT phantom, the MCNPX simulated water equivalent R eq,50% are compatible with the CSDA water equivalent ranges from the NIST database with differences of 0.7 and 4.1 mm for 160 and 115 MeV beams, respectively. - Highlights: ► Proton dose simulation based on the MCNPX 2.6.0 in homogeneous and CT phantoms. ► CT number (HU) conversion to electron density based on Schneider's approach. ► Good agreement among MCNPX, GEANT4 and FLUKA codes in a homogeneous water phantom. ► Water equivalent R 50 in CT phantoms are compatible to those of NIST database

  17. 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.

  18. 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.

  19. Ultrasonographic Quantification of Fat Content in Fatty Liver Phantoms

    International Nuclear Information System (INIS)

    Kim, Il Young; Kim, Pyo Nyun; Joo, Gyung Soo; Kim, Ho Jung; Kim, Young Beom; Lee, Byoung Ho

    1995-01-01

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

  20. 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

  1. PHANTOM: Smoothed particle hydrodynamics and magnetohydrodynamics code

    Science.gov (United States)

    Price, Daniel J.; Wurster, James; Nixon, Chris; Tricco, Terrence S.; Toupin, Stéven; Pettitt, Alex; Chan, Conrad; Laibe, Guillaume; Glover, Simon; Dobbs, Clare; Nealon, Rebecca; Liptai, David; Worpel, Hauke; Bonnerot, Clément; Dipierro, Giovanni; Ragusa, Enrico; Federrath, Christoph; Iaconi, Roberto; Reichardt, Thomas; Forgan, Duncan; Hutchison, Mark; Constantino, Thomas; Ayliffe, Ben; Mentiplay, Daniel; Hirsh, Kieran; Lodato, Giuseppe

    2017-09-01

    Phantom is a smoothed particle hydrodynamics and magnetohydrodynamics code focused on stellar, galactic, planetary, and high energy astrophysics. It is modular, and handles sink particles, self-gravity, two fluid and one fluid dust, ISM chemistry and cooling, physical viscosity, non-ideal MHD, and more. Its modular structure makes it easy to add new physics to the code.

  2. 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.

  3. The "Phantom Costs" of Florida's Citrus Industry

    OpenAIRE

    Muraro, Ronald P.; Roka, Fritz M.; Spreen, Thomas H.

    2006-01-01

    Regulatory compliance, the "phantom costs of production," is an increasingly "fact-of-life" for U.S. agriculture. A survey was developed and implemented to enumerate regulatory compliance costs for Florida's 748,500 acres citrus industry. Complying with 61 production related regulations, 643,757 hours were expended at a total annual cost of over $24.3 million.

  4. Phantom breast sensations are frequent after mastectomy

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  5. Detailing Radio Frequency Heating Induced by Coronary Stents: A 7.0 Tesla Magnetic Resonance Study

    Science.gov (United States)

    Santoro, Davide; Winter, Lukas; Müller, Alexander; Vogt, Julia; Renz, Wolfgang; Özerdem, Celal; Grässl, Andreas; Tkachenko, Valeriy; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2012-01-01

    The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR) holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF) power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF) simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR) limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study. PMID:23185498

  6. Detailing radio frequency heating induced by coronary stents: a 7.0 Tesla magnetic resonance study.

    Directory of Open Access Journals (Sweden)

    Davide Santoro

    Full Text Available The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-05-21

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

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

    International Nuclear Information System (INIS)

    Kim, Chan Hyeong; Jeong, Jong Hwi; Bolch, Wesley E; Cho, Kun-Woo; Hwang, Sung Bae

    2011-01-01

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

  9. 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)

  10. Mathematical development of a 10 years old child phantom for use in internal dosimetry

    International Nuclear Information System (INIS)

    Deus, S.F.; Poston, J.W.; Watanabe, S.

    1989-08-01

    The main objectives of this work are: 1) to develop a project of a mathematical phantom representing as far as possible a child of 10 years old and 2)to use this phantom as a base for the specific absorbed fractions (SAF) calculations in the internal organs and skeleton due to the radioisotopes most used in nuclear medicine. This phantom was similar in shape to the Fisher and Snyder one, but several changes were introduced to make the phantom more realistic. Those changes included the addition of a neck region, puting the arms outside the trunk region, changes in the trunk, head and genitalia regions shapes. Several modifications were also done in the skeleton. For instance, the head bones, rib cage, pelvis, vertebral column, scapula, clavicles and the arms and legs bones were made very close to the real anatomic shapes. Some internal organs as the brain, lungs, liver, small and large intestines were also changed as a consenquence of the above modifications. In all those cases, the changes were made not only in the shapes but also in the organs and bones position in such a way to be more representative of the 10 years old anatomic age. Estimates of the SAF obtained by the use of this phantom, resulted, as expected, significantly different from those obtained by the use of a simpler model. In other words, the ratio between the SAF in the organs of the phantom developed in this project and the SAF in the organs of the phantom similar to the adult (obtained by reducing each region of the adult phantom by the use of appropriate factor) vary from 0.37 to 5. Those differences and their meaning are also discussed. (author) [pt

  11. 3D printed cardiac phantom for procedural planning of a transcatheter native mitral valve replacement

    Science.gov (United States)

    Izzo, Richard L.; O'Hara, Ryan P.; Iyer, Vijay; Hansen, Rose; Meess, Karen M.; Nagesh, S. V. Setlur; Rudin, Stephen; Siddiqui, Adnan H.; Springer, Michael; Ionita, Ciprian N.

    2016-03-01

    3D printing an anatomically accurate, functional flow loop phantom of a patient's cardiac vasculature was used to assist in the surgical planning of one of the first native transcatheter mitral valve replacement (TMVR) procedures. CTA scans were acquired from a patient about to undergo the first minimally-invasive native TMVR procedure at the Gates Vascular Institute in Buffalo, NY. A python scripting library, the Vascular Modeling Toolkit (VMTK), was used to segment the 3D geometry of the patient's cardiac chambers and mitral valve with severe stenosis, calcific in nature. A stereolithographic (STL) mesh was generated and AutoDesk Meshmixer was used to transform the vascular surface into a functioning closed flow loop. A Stratasys Objet 500 Connex3 multi-material printer was used to fabricate the phantom with distinguishable material features of the vasculature and calcified valve. The interventional team performed a mock procedure on the phantom, embedding valve cages in the model and imaging the phantom with a Toshiba Infinix INFX-8000V 5-axis Carm bi-Plane angiography system. Results: After performing the mock-procedure on the cardiac phantom, the cardiologists optimized their transapical surgical approach. The mitral valve stenosis and calcification were clearly visible. The phantom was used to inform the sizing of the valve to be implanted. Conclusion: With advances in image processing and 3D printing technology, it is possible to create realistic patientspecific phantoms which can act as a guide for the interventional team. Using 3D printed phantoms as a valve sizing method shows potential as a more informative technique than typical CTA reconstruction alone.

  12. Integral test phantom for dosimetric quality assurance of image guided and intensity modulated stereotactic radiotherapy

    International Nuclear Information System (INIS)

    Letourneau, Daniel; Keller, Harald; Sharpe, Michael B.; Jaffray, David A.

    2007-01-01

    The objective of this work is to develop a dosimetric phantom quality assurance (QA) of linear accelerators capable of cone-beam CT (CBCT) image guided and intensity-modulated radiotherapy (IG-IMRT). This phantom is to be used in an integral test to quantify in real-time both the performance of the image guidance and the dose delivery systems in terms of dose localization. The prototype IG-IMRT QA phantom consisted of a cylindrical imaging phantom (CatPhan) combined with an array of 11 radiation diodes mounted on a 10 cm diameter disk, oriented perpendicular to the phantom axis. Basic diode response characterization was performed for 6 and 18 MV photons. The diode response was compared to planning system calculations in the open and penumbrae regions of simple and complex beam arrangements. The clinical use of the QA phantom was illustrated in an integral test of an IG-IMRT treatment designed for a clinical spinal radiosurgery case. The sensitivity of the phantom to multileaf collimator (MLC) calibration and setup errors in the clinical setting was assessed by introducing errors in the IMRT plan or by displacing the phantom. The diodes offered good response linearity and long-term reproducibility for both 6 and 18 MV. Axial dosimetry of coplanar beams (in a plane containing the beam axes) was made possible with the nearly isoplanatic response of the diodes over 360 deg. of gantry (usually within ±1%). For single beam geometry, errors in phantom placement as small as 0.5 mm could be accurately detected (in gradient ≥1%/mm). In clinical setting, MLC systematic errors of 1 mm on a single MLC bank introduced in the IMRT plan were easily detectable with the QA phantom. The QA phantom demonstrated also sufficient sensitivity for the detection of setup errors as small as 1 mm for the IMRT delivery. These results demonstrated that the prototype can accurately and efficiently verify the entire IG-IMRT process. This tool, in conjunction with image guidance capabilities

  13. Integral test phantom for dosimetric quality assurance of image guided and intensity modulated stereotactic radiotherapy.

    Science.gov (United States)

    Létourneau, Daniel; Keller, Harald; Sharpe, Michael B; Jaffray, David A

    2007-05-01

    The objective of this work is to develop a dosimetric phantom quality assurance (QA) of linear accelerators capable of cone-beam CT (CBCT) image guided and intensity-modulated radiotherapy (IG-IMRT). This phantom is to be used in an integral test to quantify in real-time both the performance of the image guidance and the dose delivery systems in terms of dose localization. The prototype IG-IMRT QA phantom consisted of a cylindrical imaging phantom (CatPhan) combined with an array of 11 radiation diodes mounted on a 10 cm diameter disk, oriented perpendicular to the phantom axis. Basic diode response characterization was performed for 6 and 18 MV photons. The diode response was compared to planning system calculations in the open and penumbrae regions of simple and complex beam arrangements. The clinical use of the QA phantom was illustrated in an integral test of an IG-IMRT treatment designed for a clinical spinal radiosurgery case. The sensitivity of the phantom to multileaf collimator (MLC) calibration and setup errors in the clinical setting was assessed by introducing errors in the IMRT plan or by displacing the phantom. The diodes offered good response linearity and long-term reproducibility for both 6 and 18 MV. Axial dosimetry of coplanar beams (in a plane containing the beam axes) was made possible with the nearly isoplanatic response of the diodes over 360 degrees of gantry (usually within +/-1%). For single beam geometry, errors in phantom placement as small as 0.5 mm could be accurately detected (in gradient > or = 1% /mm). In clinical setting, MLC systematic errors of 1 mm on a single MLC bank introduced in the IMRT plan were easily detectable with the QA phantom. The QA phantom demonstrated also sufficient sensitivity for the detection of setup errors as small as 1 mm for the IMRT delivery. These results demonstrated that the prototype can accurately and efficiently verify the entire IG-IMRT process. This tool, in conjunction with image guidance

  14. Deep brain stimulation for phantom limb pain.

    Science.gov (United States)

    Bittar, Richard G; Otero, Sofia; Carter, Helen; Aziz, Tipu Z

    2005-05-01

    Phantom limb pain is an often severe and debilitating phenomenon that has been reported in up to 85% of amputees. Its pathophysiology is poorly understood. Peripheral and spinal mechanisms are thought to play a role in pain modulation in affected individuals; however central mechanisms are also likely to be of importance. The neuromatrix theory postulates a genetically determined representation of body image, which is modified by sensory input to create a neurosignature. Persistence of the neurosignature may be responsible for painless phantom limb sensations, whereas phantom limb pain may be due to abnormal reorganisation within the neuromatrix. This study assessed the clinical outcome of deep brain stimulation of the periventricular grey matter and somatosensory thalamus for the relief of chronic neuropathic pain associated with phantom limb in three patients. These patients were assessed preoperatively and at 3 month intervals postoperatively. Self-rated visual analogue scale pain scores assessed pain intensity, and the McGill Pain Questionnaire assessed the quality of the pain. Quality of life was assessed using the EUROQOL EQ-5D scale. Periventricular gray stimulation alone was optimal in two patients, whilst a combination of periventricular gray and thalamic stimulation produced the greatest degree of relief in one patient. At follow-up (mean 13.3 months) the intensity of pain was reduced by 62% (range 55-70%). In all three patients, the burning component of the pain was completely alleviated. Opiate intake was reduced in the two patients requiring morphine sulphate pre-operatively. Quality of life measures indicated a statistically significant improvement. This data supports the role for deep brain stimulation in patients with phantom limb pain. The medical literature relating to the epidemiology, pathogenesis, and treatment of this clinical entity is reviewed in detail.

  15. 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

  16. Phantom Sensations, Supernumerary Phantom Limbs and Apotemnophilia: Three Body Representation Disorders.

    Science.gov (United States)

    Tatu, Laurent; Bogousslavsky, Julien

    2018-01-01

    Body representation disorders continue to be mysterious and involve the anatomical substrate that underlies the mental representation of the body. These disorders sit on the boundaries of neurological and psychiatric diseases. We present the main characteristics of 3 examples of body representation disorders: phantom sensations, supernumerary phantom limb, and apotemnophilia. The dysfunction of anatomical circuits that regulate body representation can sometimes have paradoxical features. In the case of phantom sensations, the patient feels the painful subjective sensation of the existence of the lost part of the body after amputation, surgery or trauma. In case of apotemnophilia, now named body integrity identity disorder, the subject wishes for the disappearance of the existing and normal limb, which can occasionally lead to self-amputation. More rarely, a brain-damaged patient with 4 existing limbs can report the existence of a supernumerary phantom limb. © 2018 S. Karger AG, Basel.

  17. Results from transient transport experiments in Rijnhuizen tokamak project: Heat convection, transport barriers and 'non-local' effects

    International Nuclear Information System (INIS)

    Mantica, P.; Gorini, G.; Hogeweij, G.M.D.; Kloe, J. de; Lopez Cardozo, N.J.; Schilham, A.M.R.

    2001-01-01

    An overview of experimental transport studies performed on the Rijnhuizen Tokamak Project (RTP) using transient transport techniques in both Ohmic and ECH dominated plasmas is presented. Modulated Electron Cyclotron Heating (ECH) and oblique pellet injection (OPI) have been used to induce electron temperature (T e ) perturbations at different radial locations. These were used to probe the electron transport barriers observed near low order rational magnetic surfaces in ECH dominated steady-state RTP plasmas. Layers of inward electron heat convection in off-axis ECH plasmas were detected with modulated ECH. This suggests that RTP electron transport barriers consist of heat pinch layers rather than layers of low thermal diffusivity. In a different set of experiments, OPI triggered a transient rise of the core T e due to an increase of the T e gradient in the 1< q<2 region. These transient transport barriers were probed with modulated ECH and found to be due to a transient drop of the electron heat diffusivity, except for off-axis ECH plasmas, where a transient inward pinch is also observed. Transient transport studies in RTP could not solve this puzzling interplay between heat diffusion and convection in determining an electron transport barrier. They nevertheless provided challenging experimental evidence both for theoretical modelling and for future experiments. (author)

  18. Scale model test results for an inverted U-tube steam generator with comparisons to heat transfer correlations

    International Nuclear Information System (INIS)

    Boucher, T.J.

    1987-01-01

    To provide data for assessment and development of thermal-hydraulic computer codes, bottom main feedwater-line-break transient simulations were performed in a scale model (Semiscale Mod-2C) of a pressurized water reactor (PWR) with conditions typical of a PWR (15.0 MPa primary pressure, 600 K steam generator inlet plenum fluid temperatures, 6.2 MPa secondary pressure). The state-of-the-art measurements in the scale model (Type III) steam generator allow for the determination of U-tube steam generator allow for the determination of U-tube steam generator secondary component interactions, tube bundle local radial heat transfer, and tube bundle and riser vapor void fractions for steady state and transient operations. To enhance the understanding of the observed phenomena, the component interactions, local heat fluxes, local secondary convective heat transfer coefficients and local vapor void fractions are discussed for steady state, full-power and transient operations. Comparisons between the measurement-derived secondary convective heat transfer coefficients and those predicted by a number of correlations, including the Chen correlation currently used in thermal-hydraulic computer codes, show that none of the correlations adequately predict the data and points out the need for the formulation of a new correlation based on this experimental data. The unique information presented herein should be of the interest to anyone involved in modeling inverted U-tube steam generator thermal-hydraulics for forced convection boiling/vaporization heat transfer. 5 refs., 13 figs., 1 tab

  19. 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.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  1. Incorporation of detailed eye model into polygon-mesh versions of ICRP-110 reference phantoms.

    Science.gov (United States)

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

    2015-11-21

    The dose coefficients for the eye lens reported in ICRP 2010 Publication 116 were calculated using both a stylized model and the ICRP-110 reference phantoms, according to the type of radiation, energy, and irradiation geometry. To maintain consistency of lens dose assessment, in the present study we incorporated the ICRP-116 detailed eye model into the converted polygon-mesh (PM) version of the ICRP-110 reference phantoms. After the incorporation, the dose coefficients for the eye lens were calculated and compared with those of the ICRP-116 data. The results showed generally a good agreement between the newly calculated lens dose coefficients and the values of ICRP 2010 Publication 116. Significant differences were found for some irradiation cases due mainly to the use of different types of phantoms. Considering that the PM version of the ICRP-110 reference phantoms preserve the original topology of the ICRP-110 reference phantoms, it is believed that the PM version phantoms, along with the detailed eye model, provide more reliable and consistent dose coefficients for the eye lens.

  2. Monte Carlo simulations in CT for the study of the surface air kerma and energy imparted to phantoms of varying size and position

    Science.gov (United States)

    Avilés Lucas, P.; Dance, D. R.; Castellano, I. A.; Vañó, E.

    2004-04-01

    A Monte Carlo computational model of CT has been developed and used to investigate the effect of various physical factors on the surface air kerma length product, the peak surface air kerma, the air kerma length product within a phantom and the energy imparted. The factors investigated were the bow-tie filter and the size, shape and position of a phantom which simulates the patient. The calculations show that the surface air kerma length product and the maximum surface air kerma are mainly dependent on phantom position and decrease along the vertical axis of the CT plane as the phantom surface moves away from the isocentre along this axis. As a result, measurements using standard body dosimetry phantoms may underestimate the skin dose for real patients. This result is specially important for CT fluoroscopic procedures: for an adult patient the peak skin dose can be 37% higher than that estimated with a standard measurement on the body AAPM (American Association of Physicists in Medicine) phantom. The results also show that the energy imparted to a phantom is mainly influenced by phantom size and is nearly independent of phantom position (within 3%) and shape (up to 5% variation). However, variations of up to 30% were found for the air kerma to regions within the AAPM body phantom when it is moved vertically. This highlights the importance of calculating doses to organs taking into account their size and position within the gantry.

  3. Phantom energy accretion onto black holes in a cyclic universe

    International Nuclear Information System (INIS)

    Sun Chengyi

    2008-01-01

    Black holes pose a serious problem in cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by phantom energy prior to turnaround before they can create any problems. In this paper, using the mechanism of phantom accretion onto black holes, we find that black holes do not disappear before phantom turnaround. But the remanent black holes will not cause any problems due to Hawking evaporation.

  4. Recruitment, Methods, and Descriptive Results of a Physiologic Assessment of Latino Farmworkers: The California Heat Illness Prevention Study.

    Science.gov (United States)

    Mitchell, Diane C; Castro, Javier; Armitage, Tracey L; Vega-Arroyo, Alondra J; Moyce, Sally C; Tancredi, Daniel J; Bennett, Deborah H; Jones, James H; Kjellstrom, Tord; Schenker, Marc B

    2017-07-01

    The California heat illness prevention study (CHIPS) devised methodology and collected physiological data to assess heat related illness (HRI) risk in Latino farmworkers. Bilingual researchers monitored HRI across a workshift, recording core temperature, work rate (metabolic equivalents [METs]), and heart rate at minute intervals. Hydration status was assessed by changes in weight and blood osmolality. Personal data loggers and a weather station measured exposure to heat. Interviewer administered questionnaires were used to collect demographic and occupational information. California farmworkers (n = 588) were assessed. Acceptable quality data was obtained from 80% of participants (core temperature) to 100% of participants (weight change). Workers (8.3%) experienced a core body temperature more than or equal to 38.5 °C and 11.8% experienced dehydration (lost more than 1.5% of body weight). Methodology is presented for the first comprehensive physiological assessment of HRI risk in California farmworkers.

  5. Hybrid pregnant reference phantom series based on adult female ICRP reference phantom

    Science.gov (United States)

    Rafat-Motavalli, Laleh; Miri-Hakimabad, Hashem; Hoseinian-Azghadi, Elie

    2018-03-01

    This paper presents boundary representation (BREP) models of pregnant female and her fetus at the end of each trimester. The International Commission on Radiological Protection (ICRP) female reference voxel phantom was used as a base template in development process of the pregnant hybrid phantom series. The differences in shape and location of the displaced maternal organs caused by enlarging uterus were also taken into account. The CT and MR images of fetus specimens and pregnant patients of various ages were used to replace the maternal abdominal pelvic organs of template phantom and insert the fetus inside the gravid uterus. Each fetal model contains 21 different organs and tissues. The skeletal model of the fetus also includes age-dependent cartilaginous and ossified skeletal components. The replaced maternal organ models were converted to NURBS surfaces and then modified to conform to reference values of ICRP Publication 89. The particular feature of current series compared to the previously developed pregnant phantoms is being constructed upon the basis of ICRP reference phantom. The maternal replaced organ models are NURBS surfaces. With this great potential, they might have the feasibility of being converted to high quality polygon mesh phantoms.

  6. Heat and nuclear radiation as risk factors for male infertility: results of a French case-control study

    International Nuclear Information System (INIS)

    Thonneau, P.F.; Rachou, E.; Ducot, B.; Multigner, L.; Velez de la Calle, J.P.; Le Martelot, M.T.

    1998-01-01

    Very few studies have investigated the possible effects of environmental radiation and heat exposure on male reproductive function. We conducted a case control study to evaluate the various infertility risk factors in the military population of the french town of Brest to investigate an apparently high incidence of infertility in couples in which the man may have been exposed to occupational nuclear radiation. These findings suggest that in addition to well known medical factors, 'potential' exposure to heat or nuclear radiation could also be risk factors for infertility. (N.C.)

  7. Initial investigation of a novel light-scattering gel phantom for evaluation of optical CT scanners for radiotherapy gel dosimetry

    International Nuclear Information System (INIS)

    Bosi, Stephen; Naseri, Pourandokht; Puran, Alicia; Davies, Justin; Baldock, Clive

    2007-01-01

    There is a need for stable gel materials for phantoms used to validate optical computerized tomography (CT) scanners used in conjunction with radiation-induced polymerizing gel dosimeters. Phantoms based on addition of light-absorbing dyes to gelatine to simulate gel dosimeters have been employed. However, to more accurately simulate polymerizing gels one requires phantoms that employ light-scattering colloidal suspensions added to the gel. In this paper, we present the initial results of using an optical CT scanner to evaluate a novel phantom in which radiation-exposed polymer gels are simulated by the addition of colloidal suspensions of varying turbidity. The phantom may be useful as a calibration transfer standard for polymer gel dosimeters. The tests reveal some phenomena peculiar to light-scattering gels that need to be taken into account when calibrating polymer gel dosimeters

  8. A comparison of methods to evaluate gray scale response of tomosynthesis systems using a software breast phantom

    Science.gov (United States)

    Sousa, Maria A. Z.; Bakic, Predrag R.; Schiabel, Homero; Maidment, Andrew D. A.

    2017-03-01

    Digital breast tomosynthesis (DBT) has been shown to be an effective imaging tool for breast cancer diagnosis as it provides three-dimensional images of the breast with minimal tissue overlap. The quality of the reconstructed image depends on many factors that can be assessed using uniform or realistic phantoms. In this paper, we created four models of phantoms using an anthropomorphic software breast phantom and compared four methods to evaluate the gray scale response in terms of the contrast, noise and detectability of adipose and glandular tissues binarized according to phantom ground truth. For each method, circular regions of interest (ROIs) were selected with various sizes, quantity and positions inside a square area in the phantom. We also estimated the percent density of the simulated breast and the capability of distinguishing both tissues by receiver operating characteristic (ROC) analysis. Results shows a sensitivity of the methods to the ROI size, placement and to the slices considered.

  9. 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.

  10. Fiscal 1974 Sunshine Project result report. Research on solar energy utilization systems (solar heat power generation); 1974 nendo taiyo energy riyo system chosa kenkyu seika hokokusho. Taiyonetsu hatsuden

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1975-03-01

    This report summarizes the fiscal 1974 research result on solar heat power generation. The following are promising as solar heat power plant sites in Japan: Large-scale sites such as the foot of volcanos, riverbed, railway site and road, medium-scale sites such as isolated island, saltpan site and industrial park, and small-scale sites such as factory site, factory roof floor, housing complex, warehouse and school. Based on the primary concept design of both curved reflector type and tower type 1,000kW class solar heat power plants, various requirements were clarified roughly. It was clarified that food, fiber and non-ferrous metal factories can cover 80-90% of their thermal energy requirements with high- temperature solar heat, while factories related to food and fiber can cover even nearly 100% of their electric power requirements with solar heat. Study was also made on specifications of a solar simulator as common use facility necessary for characteristic evaluation of equipment and materials for solar heat power generation systems. (NEDO)

  11. Influence of the PMMA and the ISO slab phantom for calibrating personal dosemeters

    International Nuclear Information System (INIS)

    Ginjaume, M.; Ortega, X.; Barbosa, A.

    2000-01-01

    Wide agreement has been achieved among the main Bodies and Organisations involved in standardisation of radiation protection, related to the operational quantities for personal dosimetry. Since their definition in 1985, several reports have been published to clarify and define the experimental set up to be used for the calibration of dosemeters in terms of the above-mentioned quantities. Among these lines, ICRU 47 has listed five different phantoms that are used for calibration and whose results were accurate, within accepted uncertainties. However, to achieve uniformity in calibration procedures, the 30 cm x 30 cm x 15 cm PMMA slab phantom was recommended. The secondary calibration Laboratory from the Institut de Techniques Energetiques at the Technical University of Catalonia (UPC) agreed with the Spanish Nacional Laboratory to adopt the recommended PMMA phantom but to improve the accuracy of the calibration procedure, by introducing a correction factor for backscatter differences in a PMMA and an ICRU slab phantom. Such corrections were of the order of 8% for the low-energy X-ray qualities. Recently, ISO in ISO 4037-3, has proposed the ISO water slab phantom which consists of a 30 cm x 30 cm x 15 cm water phantom with PMMA walls (front wall 2.5 mm thick). This new phantom could be substituted by the above mentioned PMMA phantom for radiation qualities with mean energy equal or above that of 137 Cs. The aim of this work is to compare the influence of both phantoms when calibrating personal dosemeters with photons. A set of four TL personal dosemeters that are used in the UPC personal dosimetry Service and an electronic personal dosemeter (SIEMENS EPD-2) were calibrated in terms of H p (10) and H p (0.07) using the two proposed phantoms. Calibration factors for ISO X-ray narrow spectra, 137 Cs and 60 Co were experimentally obtained for each phantom and compared. In the TL measurements, differences were found to be within TL statistical uncertainty, provided that a

  12. An externally and internally deformable, programmable lung motion phantom

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Yam; Sawant, Amit, E-mail: amit.sawant@utsouthwestern.edu [UT Southwestern Medical Center, University of Texas, Dallas, Texas 75390 (United States)

    2015-05-15

    Purpose: Most clinically deployed strategies for respiratory motion management in lung radiotherapy (e.g., gating and tracking) use external markers that serve as surrogates for tumor motion. However, typical lung phantoms used to validate these strategies are based on a rigid exterior and a rigid or a deformable-interior. Such designs do not adequately represent respiration because the thoracic anatomy deforms internally as well as externally. In order to create a closer approximation of respiratory motion, the authors describe the construction and experimental testing of an externally as well as internally deformable, programmable lung phantom. Methods: The outer shell of a commercially available lung phantom (RS-1500, RSD, Inc.) was used. The shell consists of a chest cavity with a flexible anterior surface, and embedded vertebrae, rib-cage and sternum. A custom-made insert was designed using a piece of natural latex foam block. A motion platform was programmed with sinusoidal and ten patient-recorded lung tumor trajectories. The platform was used to drive a rigid foam “diaphragm” that compressed/decompressed the phantom interior. Experimental characterization comprised of determining the reproducibility and the external–internal correlation of external and internal marker trajectories extracted from kV x-ray fluoroscopy. Experiments were conducted to illustrate three example applications of the phantom—(i) validating the geometric accuracy of the VisionRT surface photogrammetry system; (ii) validating an image registration tool, NiftyReg; and (iii) quantifying the geometric error due to irregular motion in four-dimensional computed tomography (4DCT). Results: The phantom correctly reproduced sinusoidal and patient-derived motion, as well as realistic respiratory motion-related effects such as hysteresis. The reproducibility of marker trajectories over multiple runs for sinusoidal as well as patient traces, as characterized by fluoroscopy, was within 0

  13. Calculated experiment results on the study of possibility of power-effective high-frequency plasma heating

    International Nuclear Information System (INIS)

    Kokhanenko, I.K.; Zajtsev, A.A.

    1993-01-01

    A method for plasma anomalous heating by SHF radiation with variable power characteristics is considered. On the base of automodel system theory it is shown a possibility of providing for controlled plasma burning in a mode with 'sharpening'. Anomalous phenomena, appeared in experimental investigations of the SHF discharge, are explained

  14. Results of measurements of the ion temperature profile of ECR heated plasmas in the L-2M stellarator

    International Nuclear Information System (INIS)

    Voronov, G.S.; Voronova, E.V.; Grebenshchikov, S.E.

    2005-01-01

    After boronization of the vacuum chamber of the L-2M stellarator, the confinement characteristics and the electron temperature profile changed markedly. In this connection, our immediate task was to carry out studies of the behavior of the ion temperature under these conditions. Previous measurements of Ti were performed by analyzing the energy distribution of fast hydrogen ions produced by charge exchange. In recent studies, the ion temperature was determined from Doppler broadening of spectral lines of impurity ions. With the help of a set of mirrors, the plasma radiation was focused on the entrance slit of a VMS-1 monochromator (D/F=1:6.5, F=600 mm, 1200 lines/mm,1.3 nm/mm, 200 - 800 nm). The detector was a CCD plate (1040 1 140 pixels of size 16 1 6 ∝ m) covered in part with an opaque screen. The plasma spectrum produced in the uncovered area was rapidly scanned and copied into the covered region. With this partial exposition method, the rate of recording was successfully increased up to 1000 frames per second. The instrument function of the whole system was 0.04 nm, which corresponds to Ti ∼1 eV for hydrogen and ∼17 eV for boron ions. The plasma ion temperature is considerably higher, so the accuracy of measurements of Ti is limited primarily by a low intensity of signals from the plasma with a low impurity concentration. The results of measurements of the evolution of HeII, BII, and BIV ions temperature during the ECR heating of a helium plasma are shown in the figure. The plasma density in these experiments was ∼2.10 19 m -3 , and the gyrotron pulse power was ∼200 kW. The results of measurements of Ti were compared with the time evolution of the ion temperature calculated by using the TRANSZ code. The latter includes a complete set of neoclassical equations and involves additional anomalous fluxes corresponding to accepted empirical scalings. The calculated values of Ti are in fair agreement with the measured ones

  15. A study of the short- to long-phantom dose ratios for CT scanning without table translation

    International Nuclear Information System (INIS)

    Li, Xinhua; Zhang, Da; Liu, Bob; Yang, Jie

    2014-01-01

    Purpose: For CT scanning in the stationary-table modes, AAPM Task Group 111 proposed to measure the midpoint dose on the central and peripheral axes of sufficiently long phantoms. Currently, a long cylindrical phantom is usually not available in many clinical facilities. The use of a long phantom is also challenging because of the heavy weight. In order to shed light on assessing the midpoint dose in CT scanning without table movement, the authors present a study of the short- to long-phantom dose ratios, and perform a cross-comparison of CT dose ratios on different scanner models. Methods: The authors performed Geant4-based Monte Carlo simulations with a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare), and modeled dosimetry measurements using a 0.6 cm 3 Farmer type chamber and a 10-cm long pencil ion chamber. The short (15 cm) to long (90 cm) phantom dose ratios were computed for two PMMA diameters (16 and 32 cm), two phantom axes (the center and the periphery), and a range of beam apertures (3–25 cm). The results were compared with the published data of previous studies with other multiple detector CT (MDCT) scanners and cone beam CT (CBCT) scanners. Results: The short- to long-phantom dose ratios changed with beam apertures but were insensitive to beam qualities (80–140 kV, the head and body bowtie filters) and MDCT and CBCT scanner models. Conclusions: The short- to long-phantom dose ratios enable medical physicists to make dosimetry measurements using the standard CT dosimetry phantoms and a Farmer chamber or a 10 cm long pencil chamber, and to assess the midpoint dose in long phantoms. This method provides an effective approach for the dosimetry of CBCT scanning in the stationary-table modes, and is useful for perfusion and interventional CT

  16. 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

  17. A study of the short- to long-phantom dose ratios for CT scanning without table translation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu [Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Yang, Jie [Pinnacle Health - Fox Chase Regional Cancer Center, Harrisburg, Pennsylvania 17109 (United States)

    2014-09-15

    Purpose: For CT scanning in the stationary-table modes, AAPM Task Group 111 proposed to measure the midpoint dose on the central and peripheral axes of sufficiently long phantoms. Currently, a long cylindrical phantom is usually not available in many clinical facilities. The use of a long phantom is also challenging because of the heavy weight. In order to shed light on assessing the midpoint dose in CT scanning without table movement, the authors present a study of the short- to long-phantom dose ratios, and perform a cross-comparison of CT dose ratios on different scanner models. Methods: The authors performed Geant4-based Monte Carlo simulations with a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare), and modeled dosimetry measurements using a 0.6 cm{sup 3} Farmer type chamber and a 10-cm long pencil ion chamber. The short (15 cm) to long (90 cm) phantom dose ratios were computed for two PMMA diameters (16 and 32 cm), two phantom axes (the center and the periphery), and a range of beam apertures (3–25 cm). The results were compared with the published data of previous studies with other multiple detector CT (MDCT) scanners and cone beam CT (CBCT) scanners. Results: The short- to long-phantom dose ratios changed with beam apertures but were insensitive to beam qualities (80–140 kV, the head and body bowtie filters) and MDCT and CBCT scanner models. Conclusions: The short- to long-phantom dose ratios enable medical physicists to make dosimetry measurements using the standard CT dosimetry phantoms and a Farmer chamber or a 10 cm long pencil chamber, and to assess the midpoint dose in long phantoms. This method provides an effective approach for the dosimetry of CBCT scanning in the stationary-table modes, and is useful for perfusion and interventional CT.

  18. 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

  19. Development of 1-year-old computational phantom and calculation of organ doses during CT scans using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Pan, Yuxi; Qiu, Rui; Ge, Chaoyong; Xie, Wenzhang; Li, Junli; Gao, Linfeng; Zheng, Junzheng

    2014-01-01

    With the rapidly growing number of CT examinations, the consequential radiation risk has aroused more and more attention. The average dose in each organ during CT scans can only be obtained by using Monte Carlo simulation with computational phantoms. Since children tend to have higher radiation sensitivity than adults, the radiation dose of pediatric CT examinations requires special attention and needs to be assessed accurately. So far, studies on organ doses from CT exposures for pediatric patients are still limited. In this work, a 1-year-old computational phantom was constructed. The body contour was obtained from the CT images of a 1-year-old physical phantom and the internal organs were deformed from an existing Chinese reference adult phantom. To ensure the organ locations in the 1-year-old computational phantom were consistent with those of the physical phantom, the organ locations in 1-year-old computational phantom were manually adjusted one by one, and the organ masses were adjusted to the corresponding Chinese reference values. Moreover, a CT scanner model was developed using the Monte Carlo technique and the 1-year-old computational phantom was applied to estimate organ doses derived from simulated CT exposures. As a result, a database including doses to 36 organs and tissues from 47 single axial scans was built. It has been verified by calculation that doses of axial scans are close to th