Science.gov

Sample records for dose reduction programs

  1. Dose tracking and dose auditing in a comprehensive computed tomography dose-reduction program.

    PubMed

    Duong, Phuong-Anh; Little, Brent P

    2014-08-01

    Implementation of a comprehensive computed tomography (CT) radiation dose-reduction program is a complex undertaking, requiring an assessment of baseline doses, an understanding of dose-saving techniques, and an ongoing appraisal of results. We describe the role of dose tracking in planning and executing a dose-reduction program and discuss the use of the American College of Radiology CT Dose Index Registry at our institution. We review the basics of dose-related CT scan parameters, the components of the dose report, and the dose-reduction techniques, showing how an understanding of each technique is important in effective auditing of "outlier" doses identified by dose tracking. PMID:25129210

  2. Dose Reduction Techniques

    SciTech Connect

    WAGGONER, L.O.

    2000-05-16

    As radiation safety specialists, one of the things we are required to do is evaluate tools, equipment, materials and work practices and decide whether the use of these products or work practices will reduce radiation dose or risk to the environment. There is a tendency for many workers that work with radioactive material to accomplish radiological work the same way they have always done it rather than look for new technology or change their work practices. New technology is being developed all the time that can make radiological work easier and result in less radiation dose to the worker or reduce the possibility that contamination will be spread to the environment. As we discuss the various tools and techniques that reduce radiation dose, keep in mind that the radiological controls should be reasonable. We can not always get the dose to zero, so we must try to accomplish the work efficiently and cost-effectively. There are times we may have to accept there is only so much you can do. The goal is to do the smart things that protect the worker but do not hinder him while the task is being accomplished. In addition, we should not demand that large amounts of money be spent for equipment that has marginal value in order to save a few millirem. We have broken the handout into sections that should simplify the presentation. Time, distance, shielding, and source reduction are methods used to reduce dose and are covered in Part I on work execution. We then look at operational considerations, radiological design parameters, and discuss the characteristics of personnel who deal with ALARA. This handout should give you an overview of what it takes to have an effective dose reduction program.

  3. Occupational dose reduction at Department of Energy contractor facilities: Study of ALARA programs. Status 1990

    SciTech Connect

    Dionne, B.J.; Meinhold, C.B.; Khan, T.A.; Baum, J.W.

    1992-08-01

    This report provides the US Department of Energy (DOE) and its contractors with information that will be useful for reducing occupational radiation doses at DOE`s nuclear facilities. In 1989 and 1990, health physicists from the Brookhaven National Laboratory`s (BNL) ALARA Center visited twelve DOE contractor facilities with annual collective dose equivalents greater than 100 person-rem (100 person-cSv). The health physicists interviewed radiological safety staff, engineers, and training personnel who were responsible for dose control. The status of ALARA practices at the major contractor facilities was compared with the requirements and recommendation in DOE Order 5480.11 ``Radiation Protection for Occupational Workers`` and PNL-6577 ``Health Physics Manual of Good Practices for Reducing Radiation Exposure to Levels that are as Low as Reasonably Achievable.`` The information and data collected are described and examples of successful practices are presented. The findings on the status of the DOE Contractor ALARA Programs are summarized and evaluated. In addition, the supplement to this report contains examples of good-practice documents associated with implementing the major elements of a formally documented ALARA program for a major DOE contractor facility.

  4. Industrial Waste Reduction Program

    SciTech Connect

    Not Available

    1991-10-24

    US industry generates over 12 billion tons of wastes each year. These wastes consist of undesirable by-products of industrial production that are discarded into our environment. Energy is an integral part of these wastes; it is found in the embodied energy of industrial feedstocks not optimally used, in the energy content of the wastes themselves, and in the energy needed to transport, treat, and dispose of wastes. Estimates of the potential energy savings from reducing industrial wastes range from three to four quadrillion Btu per year -- enough to meet the annual energy needs of 30 million American homes. This document presents a plan for the Industrial Waste Reduction Program, which has been designed to help achieve national goals for energy efficiency and waste minimization. The objective of the program is to improve the energy efficiency of industrial processes through cost-effective waste reduction. The initial program focus is on waste reduction opportunities in the production and use of chemicals, due to the significant amount of energy used in these activities and the large amounts of hazardous and toxic wastes they generate. The chemical industry will be the initial subject of a series of waste reduction opportunity assessments conducted as part of the program. Assessments of other industries and waste problems will follow.

  5. Simulation of dose reduction in tomosynthesis

    SciTech Connect

    Svalkvist, Angelica; Baath, Magnus

    2010-01-15

    Purpose: Methods for simulating dose reduction are valuable tools in the work of optimizing radiographic examinations. Using such methods, clinical images can be simulated to have been collected at other, lower, dose levels without the need of additional patient exposure. A recent technology introduced to healthcare that needs optimization is tomosynthesis, where a number of low-dose projection images collected at different angles is used to reconstruct section images of an imaged object. The aim of the present work was to develop a method of simulating dose reduction for digital radiographic systems, suitable for tomosynthesis. Methods: The developed method uses information about the noise power spectrum (NPS) at the original dose level and the simulated dose level to create a noise image that is added to the original image to produce an image that has the same noise properties as an image actually collected at the simulated dose level. As the detective quantum efficiency (DQE) of digital detectors operating at the low dose levels used for tomosynthesis may show a strong dependency on the dose level, it is important that a method for simulating dose reduction for tomosynthesis takes this dependency into account. By applying an experimentally determined relationship between pixel mean and pixel variance, variations in both dose and DQE in relevant dose ranges are taken into account. Results: The developed method was tested on a chest tomosynthesis system and was shown to produce NPS of simulated dose-reduced projection images that agreed well with the NPS of images actually collected at the simulated dose level. The simulated dose reduction method was also applied to tomosynthesis examinations of an anthropomorphic chest phantom, and the obtained noise in the reconstructed section images was very similar to that of an examination actually performed at the simulated dose level. Conclusions: In conclusion, the present article describes a method for simulating dose

  6. Voluntary pollution reduction programs

    SciTech Connect

    Sears, E.B.

    1997-08-01

    Despite claims that the government is reducing the amount of environmental regulation, the sheer amount of regulatory language has actually increased yearly. Yet based on media reports and citizen claims, pollution appears to go unchecked. Citizens condemn a perceived lack of government regulation of industrial pollution, while industries find themselves mired in increasingly complex regulatory programs that are sometimes far removed from real world situations. US Environmental Protection Agency (EPA) decision-makers have responded to these concerns by designing regulatory programs that abandon traditional command-and-control regulatory schemes as ill-suited to today`s pollution problems and the interests of these stakeholders. This paper analyzes the use of voluntary pollution control programs in place of command-and-control regulation. It is proposed that voluntary programs may serve as carrots to entice regulated entities to reduce pollution, but that there are a number of hurdles to their effective implementation that preclude them from being embraced as effective environmental regulatory tools. This paper reviews why agencies have moved from command-and-control regulation and examines current voluntary pollution control programs. This paper also contemplates the future of such programs.

  7. Validation of CT dose-reduction simulation

    SciTech Connect

    Massoumzadeh, Parinaz; Don, Steven; Hildebolt, Charles F.; Bae, Kyongtae T.; Whiting, Bruce R.

    2009-01-15

    The objective of this research was to develop and validate a custom computed tomography dose-reduction simulation technique for producing images that have an appearance consistent with the same scan performed at a lower mAs (with fixed kVp, rotation time, and collimation). Synthetic noise is added to projection (sinogram) data, incorporating a stochastic noise model that includes energy-integrating detectors, tube-current modulation, bowtie beam filtering, and electronic system noise. Experimental methods were developed to determine the parameters required for each component of the noise model. As a validation, the outputs of the simulations were compared to measurements with cadavers in the image domain and with phantoms in both the sinogram and image domain, using an unbiased root-mean-square relative error metric to quantify agreement in noise processes. Four-alternative forced-choice (4AFC) observer studies were conducted to confirm the realistic appearance of simulated noise, and the effects of various system model components on visual noise were studied. The ''just noticeable difference (JND)'' in noise levels was analyzed to determine the sensitivity of observers to changes in noise level. Individual detector measurements were shown to be normally distributed (p>0.54), justifying the use of a Gaussian random noise generator for simulations. Phantom tests showed the ability to match original and simulated noise variance in the sinogram domain to within 5.6%{+-}1.6% (standard deviation), which was then propagated into the image domain with errors less than 4.1%{+-}1.6%. Cadaver measurements indicated that image noise was matched to within 2.6%{+-}2.0%. More importantly, the 4AFC observer studies indicated that the simulated images were realistic, i.e., no detectable difference between simulated and original images (p=0.86) was observed. JND studies indicated that observers' sensitivity to change in noise levels corresponded to a 25% difference in dose, which

  8. Validation of CT dose-reduction simulation.

    PubMed

    Massoumzadeh, Parinaz; Don, Steven; Hildebolt, Charles F; Bae, Kyongtae T; Whiting, Bruce R

    2009-01-01

    The objective of this research was to develop and validate a custom computed tomography dose-reduction simulation technique for producing images that have an appearance consistent with the same scan performed at a lower mAs (with fixed kVp, rotation time, and collimation). Synthetic noise is added to projection (sinogram) data, incorporating a stochastic noise model that includes energy-integrating detectors, tube-current modulation, bowtie beam filtering, and electronic system noise. Experimental methods were developed to determine the parameters required for each component of the noise model. As a validation, the outputs of the simulations were compared to measurements with cadavers in the image domain and with phantoms in both the sinogram and image domain, using an unbiased root-mean-square relative error metric to quantify agreement in noise processes. Four-alternative forced-choice (4AFC) observer studies were conducted to confirm the realistic appearance of simulated noise, and the effects of various system model components on visual noise were studied. The "just noticeable difference (JND)" in noise levels was analyzed to determine the sensitivity of observers to changes in noise level. Individual detector measurements were shown to be normally distributed (p > 0.54), justifying the use of a Gaussian random noise generator for simulations. Phantom tests showed the ability to match original and simulated noise variance in the sinogram domain to within 5.6% +/- 1.6% (standard deviation), which was then propagated into the image domain with errors less than 4.1% +/- 1.6%. Cadaver measurements indicated that image noise was matched to within 2.6% +/- 2.0%. More importantly, the 4AFC observer studies indicated that the simulated images were realistic, i.e., no detectable difference between simulated and original images (p = 0.86) was observed. JND studies indicated that observers' sensitivity to change in noise levels corresponded to a 25% difference in dose

  9. Dose reduction in molecular breast imaging

    NASA Astrophysics Data System (ADS)

    Wagenaar, Douglas J.; Chowdhury, Samir; Hugg, James W.; Moats, Rex A.; Patt, Bradley E.

    2011-10-01

    Molecular Breast Imaging (MBI) is the imaging of radiolabeled drugs, cells, or nanoparticles for breast cancer detection, diagnosis, and treatment. Screening of broad populations of women for breast cancer with mammography has been augmented by the emergence of breast MRI in screening of women at high risk for breast cancer. Screening MBI may benefit the sub-population of women with dense breast tissue that obscures small tumors in mammography. Dedicated breast imaging equipment is necessary to enable detection of early-stage tumors less than 1 cm in size. Recent progress in the development of these instruments is reviewed. Pixellated CZT for single photon MBI imaging of 99mTc-sestamibi gives high detection sensitivity for early-stage tumors. The use of registered collimators in a near-field geometry gives significantly higher detection efficiency - a factor of 3.6-, which translates into an equivalent dose reduction factor given the same acquisition time. The radiation dose in the current MBI procedure has been reduced to the level of a four-view digital mammography study. In addition to screening of selected sub-populations, reduced MBI dose allows for dual-isotope, treatment planning, and repeated therapy assessment studies in the era of molecular medicine guided by quantitative molecular imaging.

  10. Industrial Waste Reduction Program. Program plan

    SciTech Connect

    Not Available

    1991-10-24

    US industry generates over 12 billion tons of wastes each year. These wastes consist of undesirable by-products of industrial production that are discarded into our environment. Energy is an integral part of these wastes; it is found in the embodied energy of industrial feedstocks not optimally used, in the energy content of the wastes themselves, and in the energy needed to transport, treat, and dispose of wastes. Estimates of the potential energy savings from reducing industrial wastes range from three to four quadrillion Btu per year -- enough to meet the annual energy needs of 30 million American homes. This document presents a plan for the Industrial Waste Reduction Program, which has been designed to help achieve national goals for energy efficiency and waste minimization. The objective of the program is to improve the energy efficiency of industrial processes through cost-effective waste reduction. The initial program focus is on waste reduction opportunities in the production and use of chemicals, due to the significant amount of energy used in these activities and the large amounts of hazardous and toxic wastes they generate. The chemical industry will be the initial subject of a series of waste reduction opportunity assessments conducted as part of the program. Assessments of other industries and waste problems will follow.

  11. Are there dangers in biologic dose reduction strategies?

    PubMed

    Chan, Christopher K Y; Holroyd, Christopher R; Mason, Alice; Zarroug, Jalaa; Edwards, Christopher J

    2016-07-01

    Biologic dose reduction strategies, for patients with inflammatory rheumatic diseases, have been assessed in multiple studies to assess outcomes compared to ongoing maintenance dosing. Whilst cessation in established disease usually leads to disease flare, dose tapering approaches for those achieving low disease activity often appear to be successful in the short term. However, tapering can be associated with a higher risk of losing disease control and rates of recapture of disease control using the original biologic dose vary between studies. Over relatively short periods of follow-up, a number of studies have shown no statistical difference in radiographic progression in patients tapering or discontinuing biologics. However, a Cochrane review found that radiographic and functional outcomes may be worse after TNF inhibitor discontinuation, and over long-term disease follow-up flares have been associated with radiographic progression and worse patient reported outcomes. To date, no studies of biological therapy dose reduction have specifically investigated the risk of increased immunogenicity or the effects on cardiovascular risk and other co-morbidities, although these remain important potential risks. In addition, whether there are greater dangers in certain dose reduction approaches such as a reduction in dose at the same frequency or a spacing of doses is not established. PMID:26970488

  12. 75 FR 76345 - Risk Reduction Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    ...The Rail Safety Improvement Act of 2008 requires the development and implementation of railroad safety risk reduction programs. Risk reduction is a comprehensive, system-oriented approach to safety that determines an operation's level of risk by identifying and analyzing applicable hazards and develops plans to mitigate that risk. Each Risk Reduction Program (RRP) is statutorily required to be......

  13. Device for the reduction of population dose

    SciTech Connect

    Kihara, T.; Uchinoumi, K.; Akagi, F.; Antoku, S.

    1982-06-01

    Conventional dental radiographic procedures do not permit direct visualization of the radiation field or the central ray. As a result, it is necessary to use a beam diameter larger than the film in order to prevent an unnecessarily high number of cone cuts or other errors during visual alignment of the cone and film. The modification of a conventional dental x-ray cone which permits the central ray to be depicted by a beam of light is described. The use of the device significantly reduced the number of cone cuts, even when small beam diameters were used. Visualization of the central ray improved radiographic accuracy and has the potential to significantly reduce the over-all dose to the population by reducing the size of the field used for dental radiography.

  14. Radiation dose reduction in computed tomography: techniques and future perspective

    PubMed Central

    Yu, Lifeng; Liu, Xin; Leng, Shuai; Kofler, James M; Ramirez-Giraldo, Juan C; Qu, Mingliang; Christner, Jodie; Fletcher, Joel G; McCollough, Cynthia H

    2011-01-01

    Despite universal consensus that computed tomography (CT) overwhelmingly benefits patients when used for appropriate indications, concerns have been raised regarding the potential risk of cancer induction from CT due to the exponentially increased use of CT in medicine. Keeping radiation dose as low as reasonably achievable, consistent with the diagnostic task, remains the most important strategy for decreasing this potential risk. This article summarizes the general technical strategies that are commonly used for radiation dose management in CT. Dose-management strategies for pediatric CT, cardiac CT, dual-energy CT, CT perfusion and interventional CT are specifically discussed, and future perspectives on CT dose reduction are presented. PMID:22308169

  15. Automated size-specific CT dose monitoring program: Assessing variability in CT dose

    SciTech Connect

    Christianson, Olav; Li Xiang; Frush, Donald; Samei, Ehsan

    2012-11-15

    that were not adjusted by patient size. Additionally, considerable differences were noted in ED{sub adj} distributions between scanners, with scanners employing iterative reconstruction exhibiting significantly lower ED{sub adj} (range: 9%-64%). Finally, a significant difference (up to 59%) in ED{sub adj} distributions was observed between institutions, indicating the potential for dose reduction. Conclusions: The authors developed a robust automated size-specific radiation dose monitoring program for CT. Using this program, significant differences in ED{sub adj} were observed between scanner models and across institutions. This new dose monitoring program offers a unique tool for improving quality assurance and standardization both within and across institutions.

  16. Dose reduction improvements in storage basins of spent nuclear fuel

    SciTech Connect

    Huang, Fan-Hsiung F.

    1997-08-13

    Spent nuclear fuel in storage basins at the Hanford Site has corroded and contaminated basin water, which has leaked into the soil; the fuel also had deposited a layer of radioactive sludge on basin floors. The SNF is to be removed from the basins to protect the nearby Columbia River. Because the radiation level is high, measures have been taken to reduce the background dose rate to as low as reasonably achievable (ALARA) to prevent radiation doses from becoming the limiting factor for removal of the SW in the basins to long-term dry storage. All activities of the SNF Project require application of ALARA principles for the workers. On the basis of these principles dose reduction improvements have been made by first identifying radiological sources. Principal radiological sources in the basin are basin walls, basin water, recirculation piping and equipment. Dose reduction activities focus on cleaning and coating basin walls to permit raising the water level, hydrolasing piping, and placing lead plates. In addition, the transfer bay floor will be refinished to make decontamination easier and reduce worker exposures in the radiation field. The background dose rates in the basin will be estimated before each task commences and after it is completed; these dose reduction data will provide the basis for cost benefit analysis.

  17. Effects of Low-Dose Mindfulness-Based Stress Reduction (MBSR-ld) on Working Adults

    ERIC Educational Resources Information Center

    Klatt, Maryanna D.; Buckworth, Janet; Malarkey, William B.

    2009-01-01

    Mindfulness-based stress reduction (MBSR) has produced behavioral, psychological, and physiological benefits, but these programs typically require a substantial time commitment from the participants. This study assessed the effects of a shortened (low-dose [ld]) work-site MBSR intervention (MBSR-ld) on indicators of stress in healthy working…

  18. Radiation dose reduction for coronary artery calcium scoring at 320-detector CT with adaptive iterative dose reduction 3D.

    PubMed

    Tatsugami, Fuminari; Higaki, Toru; Fukumoto, Wataru; Kaichi, Yoko; Fujioka, Chikako; Kiguchi, Masao; Yamamoto, Hideya; Kihara, Yasuki; Awai, Kazuo

    2015-06-01

    To assess the possibility of reducing the radiation dose for coronary artery calcium (CAC) scoring by using adaptive iterative dose reduction 3D (AIDR 3D) on a 320-detector CT scanner. Fifty-four patients underwent routine- and low-dose CT for CAC scoring. Low-dose CT was performed at one-third of the tube current used for routine-dose CT. Routine-dose CT was reconstructed with filtered back projection (FBP) and low-dose CT was reconstructed with AIDR 3D. We compared the calculated Agatston-, volume-, and mass scores of these images. The overall percentage difference in the Agatston-, volume-, and mass scores between routine- and low-dose CT studies was 15.9, 11.6, and 12.6%, respectively. There were no significant differences in the routine- and low-dose CT studies irrespective of the scoring algorithms applied. The CAC measurements of both imaging modalities were highly correlated with respect to the Agatston- (r = 0.996), volume- (r = 0.996), and mass score (r = 0.997; p < 0.001, all); the Bland-Altman limits of agreement scores were -37.4 to 51.4, -31.2 to 36.4 and -30.3 to 40.9%, respectively, suggesting that AIDR 3D was a good alternative for FBP. The mean effective radiation dose for routine- and low-dose CT was 2.2 and 0.7 mSv, respectively. The use of AIDR 3D made it possible to reduce the radiation dose by 67% for CAC scoring without impairing the quantification of coronary calcification. PMID:25754302

  19. Decreasing Methadone Dose Via Anxiety Reduction: A Treatment Manual.

    ERIC Educational Resources Information Center

    Kushner, Marlene; And Others

    This manual describes a Relaxation-Information Presentation program based on the clinical observation that anxiety is a serious barrier to detoxification for many methadone clients, and on experimental evidence indicating that expectations may play a greater role in the discomfort experienced during detoxification than the actual methadone dose.…

  20. Patient specific tube current modulation for CT dose reduction

    NASA Astrophysics Data System (ADS)

    Jin, Yannan; Yin, Zhye; Yao, Yangyang; Wang, Hui; Wu, Mingye; Kalra, Mannudeep; De Man, Bruno

    2015-03-01

    Radiation exposure during CT imaging has drawn growing concern from academia, industry as well as the general public. Sinusoidal tube current modulation has been available in most commercial products and used routinely in clinical practice. To further exploit the potential of tube current modulation, Sperl et al. proposed a Computer-Assisted Scan Protocol and Reconstruction (CASPAR) scheme [6] that modulates the tube current based on the clinical applications and patient specific information. The purpose of this study is to accelerate the CASPAR scheme to make it more practical for clinical use and investigate its dose benefit for different clinical applications. The Monte Carlo simulation in the original CASPAR scheme was substituted by the dose reconstruction to accelerate the optimization process. To demonstrate the dose benefit, we used the CATSIM package generate the projection data and perform standard FDK reconstruction. The NCAT phantom at thorax position was used in the simulation. We chose three clinical cases (routine chest scan, coronary CT angiography with and without breast avoidance) and compared the dose level with different mA modulation schemes (patient specific, sinusoidal and constant mA) with matched image quality. The simulation study of three clinical cases demonstrated that the patient specific mA modulation could significantly reduce the radiation dose compared to sinusoidal modulation. The dose benefits depend on the clinical application and object shape. With matched image quality, for chest scan the patient specific mA profile reduced the dose by about 15% compared to the sinusoid mA modulation; for the organ avoidance scan the dose reduction to the breast was over 50% compared to the constant mA baseline.

  1. Dose reduction by automatic exposure control in multidetector computed tomography: comparison between measurement and calculation.

    PubMed

    Lechel, U; Becker, C; Langenfeld-Jäger, G; Brix, G

    2009-04-01

    The aim of this study was to investigate the potential of dose reduction in multidetector computed tomography (MDCT) by current-modulated automatic exposure control (AEC) and to test the reliability of the dose estimation by the conventional CT dosimetry program CT-EXPO, when an average tube current is used. Phantom measurements were performed at a CT system with 64 detector rows for four representative examination protocols, each without and with current-modulated AEC. Organ and effective doses were measured by thermoluminescence dosimeters (TLD) at an anthropomorphic Alderson phantom and compared with those given by the calculation with CT-EXPO. The application of AEC yielded dose reductions between 27 and 40% (TLD measurements). While good linearity was observed between measured and computed effective dose values both without and with AEC, the organ doses showed large deviations between measurement and calculation. The dose to patients undergoing a MDCT examination can be reduced considerably by applying a current-modulated AEC. Dosimetric algorithms using a constant current-time product provide reliable estimates of the effective dose. PMID:18987864

  2. Dose reduction using a dynamic, piecewise-linear attenuator

    SciTech Connect

    Hsieh, Scott S.; Fleischmann, Dominik; Pelc, Norbert J.

    2014-02-15

    Purpose: The authors recently proposed a dynamic, prepatient x-ray attenuator capable of producing a piecewise-linear attenuation profile customized to each patient and viewing angle. This attenuator was intended to reduce scatter-to-primary ratio (SPR), dynamic range, and dose by redistributing flux. In this work the authors tested the ability of the attenuator to reduce dose and SPR in simulations. Methods: The authors selected four clinical applications, including routine full field-of-view scans of the thorax and abdomen, and targeted reconstruction tasks for an abdominal aortic aneurysm and the pancreas. Raw data were estimated by forward projection of the image volume datasets. The dynamic attenuator was controlled to reduce dose while maintaining peak variance by solving a convex optimization problem, assuminga priori knowledge of the patient anatomy. In targeted reconstruction tasks, the noise in specific regions was given increased weighting. A system with a standard attenuator (or “bowtie filter”) was used as a reference, and used either convex optimized tube current modulation (TCM) or a standard TCM heuristic. The noise of the scan was determined analytically while the dose was estimated using Monte Carlo simulations. Scatter was also estimated using Monte Carlo simulations. The sensitivity of the dynamic attenuator to patient centering was also examined by shifting the abdomen in 2 cm intervals. Results: Compared to a reference system with optimized TCM, use of the dynamic attenuator reduced dose by about 30% in routine scans and 50% in targeted scans. Compared to the TCM heuristics which are typically used withouta priori knowledge, the dose reduction is about 50% for routine scans. The dynamic attenuator gives the ability to redistribute noise and variance and produces more uniform noise profiles than systems with a conventional bowtie filter. The SPR was also modestly reduced by 10% in the thorax and 24% in the abdomen. Imaging with the dynamic

  3. Dose reduction using a dynamic, piecewise-linear attenuator

    PubMed Central

    Hsieh, Scott S.; Fleischmann, Dominik; Pelc, Norbert J.

    2014-01-01

    Purpose: The authors recently proposed a dynamic, prepatient x-ray attenuator capable of producing a piecewise-linear attenuation profile customized to each patient and viewing angle. This attenuator was intended to reduce scatter-to-primary ratio (SPR), dynamic range, and dose by redistributing flux. In this work the authors tested the ability of the attenuator to reduce dose and SPR in simulations. Methods: The authors selected four clinical applications, including routine full field-of-view scans of the thorax and abdomen, and targeted reconstruction tasks for an abdominal aortic aneurysm and the pancreas. Raw data were estimated by forward projection of the image volume datasets. The dynamic attenuator was controlled to reduce dose while maintaining peak variance by solving a convex optimization problem, assuming a priori knowledge of the patient anatomy. In targeted reconstruction tasks, the noise in specific regions was given increased weighting. A system with a standard attenuator (or “bowtie filter”) was used as a reference, and used either convex optimized tube current modulation (TCM) or a standard TCM heuristic. The noise of the scan was determined analytically while the dose was estimated using Monte Carlo simulations. Scatter was also estimated using Monte Carlo simulations. The sensitivity of the dynamic attenuator to patient centering was also examined by shifting the abdomen in 2 cm intervals. Results: Compared to a reference system with optimized TCM, use of the dynamic attenuator reduced dose by about 30% in routine scans and 50% in targeted scans. Compared to the TCM heuristics which are typically used without a priori knowledge, the dose reduction is about 50% for routine scans. The dynamic attenuator gives the ability to redistribute noise and variance and produces more uniform noise profiles than systems with a conventional bowtie filter. The SPR was also modestly reduced by 10% in the thorax and 24% in the abdomen. Imaging with the

  4. Fluoroscopic dose reduction using a digital television nose-reduction device

    SciTech Connect

    Albow, R.C.; Jaffe, C.C.; Orphanoudakis, S.C.; Markowitz, R.I.; Rosenfield, N.S.

    1983-07-01

    A digital video image processor, connected to a video system in a conventional pediatric fluoroscopy room, was used to determine whether the device could provide satisfactory fluoroscopic images during routine examinations when the x-ray tube was operated at substantially lower than normal radiation-dose levels. A 50% reduction resulted in image quality which was indistinguishable from conventional fluoroscopic views.

  5. Dose reduction in CT with correlated-polarity noise reduction: context-dependent spatial resolution and noise properties demonstrating two-fold dose reduction with minimal artifacts

    NASA Astrophysics Data System (ADS)

    Dobbins, James T.; Wells, Jered R.; Segars, W. Paul

    2014-03-01

    Correlated-polarity noise reduction (CPNR) is a novel noise reduction technique that uses a statistical approach to reducing noise while maintaining excellent spatial resolution and a traditional noise appearance. It was demonstrated in application to CT imaging for the first time at SPIE 2013 and showed qualitatively excellent image quality at half of normal CT dose. In this current work, we measure quantitatively the spatial resolution and noise properties of CPNR in CT imaging. To measure the spatial resolution, we developed a metrology approach that is suitable for nonlinear algorithms such as CPNR. We introduce the formalism of Signal Modification Factor, SMF(u,v), which is the ratio in frequency space of the CPNR-processed image divided by the noise-free image, averaged over an ensemble of ROIs in a given anatomical context. SMF is a nonlinear analog to the MTF. We used XCAT computer-generated anthropomorphic phantom images followed by projection space processing with CPNR. The SMF revealed virtually no effect from CPNR on spatial resolution of the images (<7% degradation at all frequencies). Corresponding contextdependent NPS measurements generated with CPNR at half-dose were about equal to the NPS of full-dose images without CPNR. This result demonstrates for the first time the quantitative determination of a two-fold reduction in dose with CPNR with less than 7% reduction in spatial resolution. We conclude that CPNR shows strong promise as a method for reduction of noise (and hence, dose) in CT. CPNR may also be used in combination with iterative reconstruction techniques for yet further dose reduction, pending further investigation.

  6. Summary of emissions reduction technology programs

    NASA Technical Reports Server (NTRS)

    Niedzwiecki, R. W.

    1977-01-01

    The NASA emissions reduction contract programs for EPA aircraft engine classes P2 (turboshaft engines), T1 (jet engines with thrust under 8000 lb), T4 (JT8D) engines), and T2 (jet engines with thrust over 8000 lb) are discussed. The most important aspects of these programs, the commonality of approaches used, the test results, and assessments regarding applications of the derived technology are summarized.

  7. Cryoradiolytic reduction of heme proteins: Maximizing dose dependent yield

    PubMed Central

    Denisov, Ilia G.; Victoria, Doreen C.; Sligar, Stephen. G.

    2007-01-01

    Radiolytic reduction in frozen solutions and crystals is a useful method for generation of trapped intermediates in protein based radical reactions. In this communication we define the conditions which provide the maximum yield of one electron reduced myoglobin at 77 K using 60Co γ-irradiation in aqueous glycerol glass. The yield reached 50% after 20 kGy, was almost complete at ∼160 kGy total dose, and does not depend on the protein concentration in the range 0.01 – 5 mM. PMID:18379640

  8. AAFE RADSCAT data reduction programs user's guide

    NASA Technical Reports Server (NTRS)

    Claassen, J. P.

    1976-01-01

    Theory, design and operation of the computer programs which automate the reduction of joint radiometer and scatterometer observations are presented. The programs reduce scatterometer measurements to the normalized scattering coefficient; whereas the radiometer measurements are converted into antenna temperatures. The programs are both investigator and user oriented. Supplementary parameters are provided to aid in the interpretation of the observations. A hierarchy of diagnostics is available to evaluate the operation of the instrument, the conduct of the experiments and the quality of the records. General descriptions of the programs and their data products are also presented. This document therefore serves as a user's guide to the programs and is therefore intended to serve both the experimenter and the program operator.

  9. Barrier Reduction Program for Women: Final Report.

    ERIC Educational Resources Information Center

    McWilliams, Katie

    Cedar Valley College's Barrier Reduction Program for Women (BRPW) offers workshops and individual career consultations to help area women meet their personal needs, increase their knowledge of career opportunities, and realize their individual potential. This descriptive and evaluative report begins by examining the diverse characteristics and…

  10. Cyclosporine dose reduction by ketoconazole administration in renal transplant recipients.

    PubMed

    First, M R; Schroeder, T J; Alexander, J W; Stephens, G W; Weiskittel, P; Myre, S A; Pesce, A J

    1991-02-01

    Cyclosporine metabolism occurs in the liver via hepatic cytochrome P-450 microsomal enzymes. Ketoconazole, an imidazole derivative, has been shown to inhibit the cytochrome P-450 enzyme system. Thirty-six renal transplant recipients receiving cyclosporine as part of a triple immunosuppressive drug regimen were started on 200 mg/day of oral ketoconazole. The dose of cyclosporine was reduced by 70% at the start of ketoconazole; this dose reduction was based on our previous experience with concomitant cyclosporine-ketoconazole therapy. Ketoconazole was started in patients who had been on cyclosporine for between 10 days and 74 months. The mean cyclosporine dose was 420 mg/day (5.9 mg/kg/day) before starting ketoconazole and 66 mg/day (0.9 mg/kg/day) one year after the addition of ketoconazole; this represents a cyclosporine dose reduction of 84.7% (P less than 0.0001). The mean trough whole-blood cyclosporine concentrations measured by HPLC, were 130 ng/mL preketoconazole and 149 ng/mL after 1 year of combination therapy. Mean serum creatinine and BUN levels were unchanged before and during ketoconazole administration, and no changes in liver function tests were noted. Cyclosporine pharmacokinetics were performed before and after at least three weeks of ketoconazole. Hourly whole-blood samples were measured by HPLC (parent cyclosporine only) and TDX (parent + metabolites). Combination therapy resulted in decreases in the maximum blood concentration and the steady-state volume of distribution divided by the fractional absorption, and increases in mean residence time and the parent-to-parent plus metabolite ratio (calculated by dividing the HPLC by the TDX value). The addition of ketoconazole to cyclosporine-treated patients resulted in a significant inhibition of cyclosporine metabolism and decrease in the dosage. There was minimal nephrotoxicity, and only four rejection episodes occurred on combined therapy. The concomitant administration of the two drugs was well

  11. Radiation dose reduction in pediatric abdominal CT scanning

    SciTech Connect

    Kamel, I.R.

    1993-01-01

    A clinical trial was designed to test whether a significantly lower radiation dose technique could be used for pediatric abdominal CT scanning without loss of diagnostic image quality. The study included pediatric patients referred to radiology from the Children's Hospital and clinics at The University of Michigan. Seventy-eight cases were included in the study, 36 cases in the experimental group and 42 in the control group. Patient characteristics in both groups were comparable in every respect except for the technical factors used to expose the pelvis. Patients in the experimental group were scanned with a technique using 80 mAs while those in the control group were scanned with the conventional technique of 240 mAs. Therefore, the radiation dose to the pelvis was three times higher in the control group than in the experimental group. Scans were evaluated by two experienced pediatric radiologists who assessed anatomical details, image resolution and the degree of confidence in reaching a diagnosis. The low-mAs technique did not result in reduction of diagnostic image quality or the confidence in reaching a diagnosis. In conclusion, the radiation dose resulting from pediatric CT of the pelvis may be reduced by a factor of three with equivalent medical benefit.

  12. Iterative methods for dose reduction and image enhancement in tomography

    DOEpatents

    Miao, Jianwei; Fahimian, Benjamin Pooya

    2012-09-18

    A system and method for creating a three dimensional cross sectional image of an object by the reconstruction of its projections that have been iteratively refined through modification in object space and Fourier space is disclosed. The invention provides systems and methods for use with any tomographic imaging system that reconstructs an object from its projections. In one embodiment, the invention presents a method to eliminate interpolations present in conventional tomography. The method has been experimentally shown to provide higher resolution and improved image quality parameters over existing approaches. A primary benefit of the method is radiation dose reduction since the invention can produce an image of a desired quality with a fewer number projections than seen with conventional methods.

  13. Order of magnitude reduction of fluoroscopic x-ray dose

    NASA Astrophysics Data System (ADS)

    Bal, Abhinav; Robert, Normand; Machan, Lindsay; Deutsch, Meir; Kisselgoff, David; Babyn, Paul; Rowlands, John A.

    2012-03-01

    The role of fluoroscopic imaging is critical for diagnostic and image guided therapy. However, fluoroscopic imaging can require significant radiation leading to increased cancer risk and non-stochastic effects such as radiation burns. Our purpose is to reduce the exposure and dose to the patient by an order of magnitude in these procedures by use of the region of interest method. Method and Materials: Region of interest fluoroscopy (ROIF) uses a partial attenuator. The central region of the image has full exposure while the image periphery, there to provide context only, has a reduced exposure rate. ROIF using a static partial attenuator has been shown in our previous studies to reduce the dose area product (DAP) to the patient by at least 2.5 times. Significantly greater reductions in DAP would require improvements in flat panel detectors performance at low x-ray exposures or a different x-ray attenuation strategy. Thus we have investigated a second, dynamic, approach. We have constructed an x-ray shutter system allowing a normal x-ray exposure in the region of interest while reducing the number of x-ray exposures in the periphery through the rapid introduction, positioning and removal of an x-ray attenuating shutter to block radiation only for selected frames. This dynamic approach eliminates the DQE(0) loss associated with the use of static partial attenuator applied to every frame thus permitting a greater reduction in DAP. Results: We have compared the two methods by modeling and determined their fundamental limits.

  14. Reduction of radiation dose to patients undergoing barium enema by dose audit.

    PubMed

    Yu, S K; Cheung, Y K; Chan, T L; Kung, C M; Yuen, M K

    2001-02-01

    Nowadays, new fluoroscopic machines are usually equipped with a dose-area product (DAP) meter for dose measurement. In our hospital, DAP meters have been used in the Diagnostic Radiology Department for dose audit since June 1997. Demographic patient data, name of radiologist, fluoroscopic duration and DAP readings of every case were recorded by radiographers. In early 1999, questionnaires were distributed to radiologists who had performed fluoroscopic examinations during the auditing period. 23 radiologists with varying years of experience completed the questionnaire and their practice was analysed. Since familiarization with the examination technique would affect radiologists' practice, these radiologists were divided into two groups for analysis. Radiologists with less than 3 years of experience were grouped together as junior radiologists, whilst others were grouped as senior radiologists. Results of the questionnaire indicated that radiologists generally found DAP meters useful for dose evaluation in the process of technique refinement. Radiologists aware of being under continuous surveillance of their practice showed significant reduction of doses (junior radiologists 25%, p<0.005; senior radiologists 36%, p<0.05) and fluoroscopic times (junior radiologists 36%, p<0.001; senior radiologists 18%, p<0.05) compared with radiologists who were unaware that they were under surveillance but with similar radiological experience. This effect is believed to be because of increased awareness of radiation dose through audit. In addition, this "audit effect" may also affect junior radiologists in decision-making regarding the number of radiographs (p<0.05), but no effect was found for senior radiologists (p>0.5). PMID:11718389

  15. Characterization of adaptive statistical iterative reconstruction algorithm for dose reduction in CT: A pediatric oncology perspective

    SciTech Connect

    Brady, S. L.; Yee, B. S.; Kaufman, R. A.

    2012-09-15

    Purpose: This study demonstrates a means of implementing an adaptive statistical iterative reconstruction (ASiR Trade-Mark-Sign ) technique for dose reduction in computed tomography (CT) while maintaining similar noise levels in the reconstructed image. The effects of image quality and noise texture were assessed at all implementation levels of ASiR Trade-Mark-Sign . Empirically derived dose reduction limits were established for ASiR Trade-Mark-Sign for imaging of the trunk for a pediatric oncology population ranging from 1 yr old through adolescence/adulthood. Methods: Image quality was assessed using metrics established by the American College of Radiology (ACR) CT accreditation program. Each image quality metric was tested using the ACR CT phantom with 0%-100% ASiR Trade-Mark-Sign blended with filtered back projection (FBP) reconstructed images. Additionally, the noise power spectrum (NPS) was calculated for three common reconstruction filters of the trunk. The empirically derived limitations on ASiR Trade-Mark-Sign implementation for dose reduction were assessed using (1, 5, 10) yr old and adolescent/adult anthropomorphic phantoms. To assess dose reduction limits, the phantoms were scanned in increments of increased noise index (decrementing mA using automatic tube current modulation) balanced with ASiR Trade-Mark-Sign reconstruction to maintain noise equivalence of the 0% ASiR Trade-Mark-Sign image. Results: The ASiR Trade-Mark-Sign algorithm did not produce any unfavorable effects on image quality as assessed by ACR criteria. Conversely, low-contrast resolution was found to improve due to the reduction of noise in the reconstructed images. NPS calculations demonstrated that images with lower frequency noise had lower noise variance and coarser graininess at progressively higher percentages of ASiR Trade-Mark-Sign reconstruction; and in spite of the similar magnitudes of noise, the image reconstructed with 50% or more ASiR Trade-Mark-Sign presented a more

  16. Low Dose MDCT with Tube Current Modulation: Role in Detection of Urolithiasis and Patient Effective Dose Reduction

    PubMed Central

    Kakkar, Chandan; Sripathi, Smiti; Parakh, Anushri; Shrivastav, Rajendra

    2016-01-01

    Introduction Urolithiasis is one of the major, recurring problem in young individuals and CT being the commonest diagnostic modality used. In order to reduce the radiation dose to the patient who are young and as stone formation is a recurring process; one of the simplest way would be, low dose CT along with tube current modulation. Aim Aim of this study was to compare the sensitivity and specificity of low dose (70mAs) with standard dose (250mAs) protocol in detecting urolithiasis and to define the tube current and mean effective patient dose by these protocols. Materials and Methods A prospective study was conducted in 200 patients over a period of 2 years with acute flank pain presentation. CT was performed in 100 cases with standard dose and another 100 with low dose protocol using tube current modulation. Sensitivity and specificity for calculus detection, percentage reduction of dose and tube current with low dose protocol was calculated. Results Urolithiasis was detected in 138 patients, 67 were examined by high dose and 71 were by low dose protocol. Sensitivity and Specificity of low dose protocol was 97.1% and 96.4% with similar results found in high BMI patients. Tube current modulation resulted in reduction of effective tube current by 12.17%. The mean effective patient dose for standard dose was 10.33 mSv whereas 2.92 mSv for low dose with 51.13–53.8% reduction in low dose protocol. Conclusion The study has reinforced that low-dose CT with tube current modulation is appropriate for diagnosis of urolithiasis with significant reduction in tube current and patient effective dose. PMID:27437322

  17. Feedback Control for Noise Reduction Program

    NASA Astrophysics Data System (ADS)

    Tucker, Jerry H.

    2002-12-01

    As part of Langley Research Center's continuing noise reduction program, an active noise control system (ANC) is being developed to suppress noise inside an aircraft cabin. This interior noise reduction system consists of the following major components: 1. Several accelerometers. 2. An input amplifier. 3. A digital signal processor (DSP) system that includes an analog to digital converter (ADC) and a digital to analog converter (DAC). 4. A high voltage power amplifier. 5. PZT actuators. 6. Power supply and distribution. The accelerometers detect interior panel vibrations. The accelerometer signals are fed to the input amplifier where they are conditioned prior to being sent to the ADC. The DSP receives the digitized signals form the ADC, processes these signals, and sends the result to the DAC. The DAC's analog output is used as input to the high voltage power amplifier. The power amplifier drives the PZT actuators to cancel noise form 50 to 1,300 Hz. The specific area of concern for this work was development of a DSP system that could be used for an actual flight demonstration. It was decided to base the system on a commercially available DSP board, the Spectrum Digital eZdsp. This was complicated by the fact that the ADC and DAC capabilities available on the eZdsp board were not sufficient to meet the system specification. Designing and fabricating a special ADC and DAC daughter card for the eZdsp circumvented this problem. The DSP system hardware has been successfully tested and is currently being integrated into the complete noise reduction system. This work has been completed in collaboration with another ASEE Fellow, Dr.William Edmonson from Hampton University and was conducted under the direction of the principle investigator, Dr. Qamar A. Shams of the Instrumentation Systems Development Branch, as part of a continuing noise reduction program.

  18. [Phantom Study on Dose Reduction Using Iterative Reconstruction in Low-dose Computed Tomography for Lung Cancer Screening].

    PubMed

    Minehiro, Kaori; Takata, Tadanori; Hayashi, Hiroyuki; Sakuda, Keita; Nunome, Haruka; Kawashima, Hiroko; Sanada, Shigeru

    2015-12-01

    We investigated dose reduction ability of an iterative reconstruction technology for low-dose computed tomography (CT) for lung cancer screening. The Sinogram Affirmed Iterative Reconstruction (SAFIRE) provided in a multi slice CT system, Somatom Definition Flash (Siemens Healthcare) was used. An anthropomorphic chest phantom (N-1, Kyoto Kagaku) was scanned at volume CT dose index (CTDIvol) of 0.50-11.86 mGy with 120 kV. For noise (standard deviation) and contrast-to-noise ratio (CNR) measurements, CTP486 and CTP515 modules in the Catphan (The Phantom Laboratory) were scanned. Radiological technologists were participated in the perceptual comparison. SAFIRE reduced the SD values by approximately 50% compared with filter back projection (FBP). The estimated dose reduction rates by SAFIRE determined from the perceptual comparison was approximately 23%, while 75% dose reduction rate was expected from the SD value reduction of 50%. PMID:26685831

  19. Established and emerging dose reduction methods in cardiac computed tomography.

    PubMed

    Small, Gary R; Kazmi, Mustapha; Dekemp, Robert A; Chow, Benjamin J W

    2011-08-01

    Cardiac computed tomography (CT) is a non-invasive modality that is commonly used as an alternative to invasive coronary angiography for the investigation of coronary artery disease. The enthusiasm for this technology has been tempered by a growing appreciation of the potential risks of malignancy associated with the use of ionising radiation. In the spirit of minimizing patient risk, the medical profession and industry have worked hard to developed methods and protocols to reduce patient radiation exposure while maintaining excellent diagnostic accuracy. A complete understanding of radiation reduction techniques will allow clinicians to reduce patient risk while providing an important diagnostic service. This review will consider the established and emerging techniques that may be adopted to reduce patient absorbed doses from x-ray CT. By modifying (1) x-ray tube output, (2) imaging time (scan duration), (3) imaging distance (scan length) and (4) the appropriate use of shielding, clinicians will be able to adhere to the 'as low as reasonably achievable (ALARA)' principle. PMID:21630110

  20. Program documentation crew system vidar data reduction (CSVIDR) program

    NASA Technical Reports Server (NTRS)

    Vanwie, H. B.

    1976-01-01

    The Crew System Vidar Data Reduction (CSVIDR) program was written to process selected portions of data acquired from long term tests of space shuttle crew equipment. Data are recorded on a seven track computer compatible tape using the Vidar autodata eight processing system. The input tape is in a six bit binary coded decimal format. The 1110 hardware conversion option is used to convert all data from a BCD format to Fieldata since the majority of the data is output without further conversion. Data is retrieved from a character string, calibrated, tabulated, printed, and output on a fixed sample rate tape for use as input to a general purpose plot program.

  1. A Program for Calculating Radiation Dose Rates.

    Energy Science and Technology Software Center (ESTSC)

    1986-01-27

    Version 00 SMART calculates radiation dose rate at the center of the outer cask surface. It can be applied to determine the radiation dose rate on each cask if source conditions, characteristic function, and material conditions in the bottle regions are given. MANYCASK calculates radiation dose rate distribution in a space surrounded by many casks. If the dose rate on each cask surface can be measured, MANYCASK can be applied to predict dose spatial dosemore » rate distribution for any case of cask configuration.« less

  2. Using Acceptance and Commitment Therapy during Methadone Dose Reduction: Rationale, Treatment Description, and a Case Report

    PubMed Central

    Stotts, Angela L.; Masuda, Akihiko; Wilson, Kelly

    2010-01-01

    Many clients who undergo methadone maintenance (MM) treatment for heroin and other opiate dependence prefer abstinence from methadone. Attempts at methadone detoxification are often unsuccessful, however, due to distressing physical as well as psychological symptoms. Outcomes from a MM client who voluntarily participated in an Acceptance and Commitment Therapy (ACT) – based methadone detoxification program are presented. The program consisted of a 1-month stabilization and 5-month gradual methadone dose reduction period, combined with weekly individual ACT sessions. Urine samples were collected twice weekly to assess for use of illicit drugs. The participant successfully completed the program and had favorable drug use outcomes during the course of treatment, and at the one-month and one-year follow-ups. Innovative behavior therapies, such as ACT, that focus on acceptance of the inevitable distress associated with opiate withdrawal may improve methadone detoxification outcomes. PMID:20628479

  3. Patient radiation dose reduction using an X-ray imaging noise reduction technology for cardiac angiography and intervention.

    PubMed

    Nakamura, Shigeru; Kobayashi, Tomoko; Funatsu, Atsushi; Okada, Tadahisa; Mauti, Maria; Waizumi, Yuki; Yamada, Shinichi

    2016-05-01

    Coronary angiography and intervention can expose patients to high radiation dose. This retrospective study quantifies the patient dose reduction due to the introduction of a novel X-ray imaging noise reduction technology using advanced real-time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure in interventional cardiology. Patient, procedure and radiation dose data were retrospectively collected in the period August 2012-August 2013 for 883 patients treated with the image noise reduction technology (referred as "new system"). The same data were collected for 1083 patients in the period April 2011-July 2012 with a system using state-of-the-art image processing and reference acquisition chain (referred as "reference system"). Procedures were divided into diagnostic (CAG) and intervention (PCI). Acquisition parameters such as fluoroscopy time, volume of contrast medium, number of exposure images and number of stored fluoroscopy images were collected to classify procedure complexity. The procedural dose reduction was investigated separately for three main cardiologists. The new system provides significant dose reduction compared to the reference system. Median DAP values decreased for all procedures (p < 0.0001) from 172.7 to 59.4 Gy cm(2), for CAG from 155.1 to 52.0 Gy cm(2) and for PCI from 229.0 to 85.8 Gy cm(2) with reduction quantified at 66, 66 and 63 %, respectively. Based on median values, the dose reduction for all procedures was 68, 60 and 67 % for cardiologists 1, 2 and 3, respectively. The X-ray imaging technology combining advanced real-time image noise reduction algorithms and anatomy-specific optimized fluoroscopy and cine acquisition chain provides 66 % patient dose reduction in interventional cardiology. PMID:25840815

  4. Optimal dose reduction in computed tomography methodologies predicted from real-time dosimetry

    NASA Astrophysics Data System (ADS)

    Tien, Christopher Jason

    Over the past two decades, computed tomography (CT) has become an increasingly common and useful medical imaging technique. CT is a noninvasive imaging modality with three-dimensional volumetric viewing abilities, all in sub-millimeter resolution. Recent national scrutiny on radiation dose from medical exams has spearheaded an initiative to reduce dose in CT. This work concentrates on dose reduction of individual exams through two recently-innovated dose reduction techniques: organ dose modulation (ODM) and tube current modulation (TCM). ODM and TCM tailor the phase and amplitude of x-ray current, respectively, used by the CT scanner during the scan. These techniques are unique because they can be used to achieve patient dose reduction without any appreciable loss in image quality. This work details the development of the tools and methods featuring real-time dosimetry which were used to provide pioneering measurements of ODM or TCM in dose reduction for CT.

  5. Sapphire statistical characterization and risk reduction program

    NASA Astrophysics Data System (ADS)

    McClure, Donald R.; Cayse, Robert; Black, David R.; Goodrich, Steven M.; Lagerloef, K. Peter D.; Harris, Daniel C.; McCullum, Dale; Platus, Daniel H.; Patty, Charles E., Jr.; Polvani, Robert S.

    2001-09-01

    The Sapphire Statistical Characterization and Risk Reduction Program tested 1400 4-point flexure bars with different crystal orientations at different temperatures to establish a mechanical strength database for engineering design. Sapphire coupons were selected to represent surfaces on two different missile windows and a missile dome. Sapphire was obtained from the same suppliers used for the windows or dome and, as much as possible, coupons were fabricated in the same manner as the corresponding part of the window or dome. For one missile window, sapphire from one fabricator was 50% stronger than sapphire made to the same specifications from the same blanks by another fabricator. In laser thermal shock tests, sapphire performed better than predicted from flexure tests. Of several nondestructive methods evaluated for their ability to identify mechanically weak specimens, only x-ray topography was correlated with strength for a limited set of specimens.

  6. Exposure dose reduction during lateral spine test with water filter.

    PubMed

    Kim, Chang-Gyu

    2016-05-18

    To minimize exposure dose during lateral spine X-Ray testing and obtain optimal image for diagnosis a water filter was made to measure and evaluate dose distribution. When applying the water filter, as thickness increased exposure dose decreased. When applying 2 cm of water filter, clarity of contrast and boundary was found to be 4.5 ± 0.5 and resolution was found to be 2.00 ± 0.5 Lp/mm which was almost identical image quality compared to not applying water filter which showed clarity of contrast and boundary of 5.0 ± 0.0, and resolution of 2.50 ± 0.0 Lp/mm, while reducing exposure dose by 55%. This result is expected to have many uses as important basic data to predict exposure dose of patients and to minimize medical exposure dose through applying water filters during lateral spine X-Ray testing. PMID:26684401

  7. Radiation Dose Reduction Efficiency of Buildings after the Accident at the Fukushima Daiichi Nuclear Power Station

    PubMed Central

    Monzen, Satoru; Hosoda, Masahiro; Osanai, Minoru; Tokonami, Shinji

    2014-01-01

    Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55±0.04, 0.15±0.02, and 0.19±0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites. PMID:24999992

  8. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 MgY for the parotid gland, 0.15 MgY for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field.

  9. The role of dose reduction with NSAID use.

    PubMed

    Matthews, Michele L

    2013-11-01

    Effective pain relief with use of nonsteroidal anti-inflammatory drugs (NSAIDs) may come at the cost of an increased risk for serious cardiovascular (CV), gastrointestinal (GI), and renal complications. Research has shown that these adverse events are more likely to occur with higher NSAID dosing and in individuals with a preexisting risk for CV and GI complications. To minimize the potential risk for an adverse event, numerous regulatory bodies and medical societies recommend using the lowest effective NSAID dose for the shortest time necessary. One potential strategy is to offer patients lower doses of standard NSAID formulations. However, efforts to modify physician prescribing behavior may be challenging because of concerns regarding the potential for suboptimal pain management. Another strategy has emerged through use of new technology that produces submicron NSAID formulations. This new technology is also an approach that could provide effective pain relief at low doses. This article reviews the role of dose and duration in the risk for NSAID-associated adverse events, and discusses the potential benefits associated with new low-dose submicron NSAID formulations. PMID:24494606

  10. Space Radiation Quality Factors and the Delta Ray Dose and Dose-Rate Reduction Effectiveness Factor.

    PubMed

    Cucinotta, Francis A; Cacao, Eliedonna; Alp, Murat

    2016-03-01

    In this paper, the authors recommend that the dose and dose-rate effectiveness factor used for space radiation risk assessments should be based on a comparison of the biological effects of energetic electrons produced along a cosmic ray particles path in low fluence exposures to high dose-rate gamma-ray exposures of doses of about 1 Gy. Methods to implement this approach are described. PMID:26808878

  11. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

  12. Evaluation of the Advanced Subsonic Technology Program Noise Reduction Benefits

    NASA Technical Reports Server (NTRS)

    Golub, Robert A.; Rawls, John W., Jr.; Russell, James W.

    2005-01-01

    This report presents a detailed evaluation of the aircraft noise reduction technology concepts developed during the course of the NASA/FAA Advanced Subsonic Technology (AST) Noise Reduction Program. In 1992, NASA and the FAA initiated a cosponsored, multi-year program with the U.S. aircraft industry focused on achieving significant advances in aircraft noise reduction. The program achieved success through a systematic development and validation of noise reduction technology. Using the NASA Aircraft Noise Prediction Program, the noise reduction benefit of the technologies that reached a NASA technology readiness level of 5 or 6 were applied to each of four classes of aircraft which included a large four engine aircraft, a large twin engine aircraft, a small twin engine aircraft and a business jet. Total aircraft noise reductions resulting from the implementation of the appropriate technologies for each class of aircraft are presented and compared to the AST program goals.

  13. Update on radiation safety and dose reduction in pediatric neuroradiology.

    PubMed

    Mahesh, Mahadevappa

    2015-09-01

    The number of medical X-ray imaging procedures is growing exponentially across the globe. Even though the overall benefit from medical X-ray imaging procedures far outweighs any associated risks, it is crucial to take all necessary steps to minimize radiation risks to children without jeopardizing image quality. Among the X-ray imaging studies, except for interventional fluoroscopy procedures, CT studies constitute higher dose and therefore draw considerable scrutiny. A number of technological advances have provided ways for better and safer CT imaging. This article provides an update on the radiation safety of patients and staff and discusses dose optimization in medical X-ray imaging within pediatric neuroradiology. PMID:26346142

  14. 48 CFR 52.223-10 - Waste Reduction Program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 2 2011-10-01 2011-10-01 false Waste Reduction Program. 52.223-10 Section 52.223-10 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION (CONTINUED) CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 52.223-10 Waste Reduction Program....

  15. 48 CFR 52.223-10 - Waste Reduction Program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Waste Reduction Program. 52.223-10 Section 52.223-10 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION (CONTINUED) CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 52.223-10 Waste Reduction Program....

  16. Pesticide Reduction Programs in Denmark, the Netherlands, and Sweden.

    ERIC Educational Resources Information Center

    Hurst, Peter

    1992-01-01

    The Netherlands, Denmark, and Sweden are leaders in introducing comprehensive and targeted risk reduction programs for pesticides. Describes these programs and their implementation, incorporating material obtained through interviews with representatives of the main constituencies involved in reduction Tables list pesticides that do not meet the…

  17. Matrix bandwidth and profile reduction. [computer programs/permutations

    NASA Technical Reports Server (NTRS)

    Crane, H. L., Jr.; Gibbs, N. E.; Poole, W. G., Jr.; Stockmeyer, P. K.

    1975-01-01

    This program, REDUCE, reduces the bandwidth and profile of sparse symmetric matrices, using row and corresponding column permutations. It is a realization of the algorithm described by the authors elsewhere. It was extensively tested and compared with several other programs and was found to be considerably faster than the others, superior for bandwidth reduction and as satisfactory as any other for profile reduction.

  18. AN APPROACH TO REDUCTION OF UNCERTAINTIES IN INTERNAL DOSES RECONSTRUCTED FOR THE TECHA RIVER POPULATION

    SciTech Connect

    Degteva, M. O.; Shagina, N. B.; Tolstykh, E. I.; Bougrov, N. G.; Zalyapin, V. I.; Anspaugh, L. R.; Napier, Bruce A.

    2007-12-01

    A methodology is being developing for reduction of uncertainties in estimates of internal dose for residents of the Techa Riverside communities, who were exposed as a result of releases of radionuclides from the Mayak plutonium-production facility in 1949–1956. The “Techa River Dosimetry System” (TRDS) was specifically elaborated for reconstruction of doses. A preliminary analysis of uncertainty for doses estimated using the current version of the TRDS showed large ranges in the uncertainty of internal absorbed dose and led to suggestions of methods to reduce uncertainties. The new methodological approaches described in this paper will allow for significant reduction of uncertainties of 90Sr-dose. The major sources of reduction are in making use of individual measured values of 90Sr and through development of a Household Registry to associate unmeasured persons with measured persons living in the same household(s).

  19. An approach to reduction of uncertainties in internal doses reconstructed for the Techa River population.

    PubMed

    Degteva, M O; Shagina, N B; Tolstykh, E I; Bougrov, N G; Zalyapin, V I; Anspaugh, L R; Napier, B A

    2007-01-01

    A methodology was developed for reduction of uncertainties in estimates of internal dose for residents of the Techa Riverside communities, who were exposed as a result of releases of radionuclides from the Mayak plutonium production facility in 1949-56. The 'Techa River Dosimetry System' (TRDS) was specifically elaborated for reconstruction of doses. A preliminary analysis of uncertainty for doses estimated using the current version of the TRDS showed large ranges in the uncertainty of internal absorbed dose and led to suggestions of methods to reduce uncertainties. The new methodological approaches described in this paper will allow for significant reduction of uncertainties of 90Sr-dose. The major sources of reduction are: making use of individual measured values of 90Sr and through development of a Household Registry to associate unmeasured persons with measured persons living in the same household(s). PMID:17848387

  20. Developing reimbursable clinical pharmacy programs: pharmacokinetic dosing service.

    PubMed

    Moore, T D; Schneider, P J; Nold, E G

    1979-11-01

    The development, operation and evaluation of a pharmacy-conducted pharmacokinetic dosing service is described. Pharmacists recommend individualized drug dosing regimens based on pharmacokinetic models and equations clinically tested for accuracy by the pharmacy department. Pharmacokinetic values are determined with the aid of online computer programs developed by the department. Drug assays are provided by the hospital's laboratory. All of the department's pharmacists were trained to provide the 24-hour service. The pharmacy department's $20 pharmacokinetic dosing service fee is reimbursed by Blue Cross. The pharmacokinetic dosing service is the first nonteaching, nonproduct-oriented pharmaceutical service whose cost-effectiveness has been recognized by a third-party payer. PMID:517538

  1. Collective dose as a performance measure for occupational radiation protection programs: Issues and recommendations

    SciTech Connect

    Strom, D.J.; Harty, R.; Hickey, E.E.; Martin, J.B.; Peffers, M.S.; Kathren, R.L.

    1998-07-01

    Collective dose is one of the performance measures used at many US Department of Energy (DOE) contractor facilities to quantitatively assess the objectives of the radiation protection program. It can also be used as a management tool to improve the program for keeping worker doses as low as reasonably achievable (ALARA). Collective dose is used here to mean the sum of all total effective dose equivalent values for all workers in a specified group over a specified time. It is often used as a surrogate estimate of radiological risk. In principle, improvements in radiation protection programs and procedures will result in reduction of collective dose, all other things being equal. Within the DOE, most frequently, a single collective dose number, which may or may not be adjusted for workload and other factors, is used as a performance measure for a contractor. The purpose of this report is to evaluate the use of collective dose as a performance measure for ALARA programs at DOE sites.

  2. Hanford Dose Overview Program: standardized methods and data for Hanford environmental dose calculations. Rev. 1

    SciTech Connect

    McCormack, W.D.; Ramsdell, J.V.; Napier, B.A.

    1984-05-01

    This document serves as a guide to Hanford contractors for obtaining or performing Hanford-related environmental dose calculations. Because environmental dose estimation techniques are state-of-the-art and are continually evolving, the data and standard methods presented herein will require periodic revision. This document is scheduled to be updated annually, but actual changes to the program will be made more frequently if required. For this reason, PNL's Occupational and Environmental Protection Department should be contacted before any Hanford-related environmental dose calculation is performed. This revision of the Hanford Dose Overview Program Report primarily reflects changes made to the data and models used in calculating atmospheric dispersion of airborne effluents at Hanford. The modified data and models are described in detail. In addition, discussions of dose calculation methods and the review of calculation results have been expanded to provide more explicit guidance to the Hanford contractors. 19 references, 30 tables.

  3. [Reduction of radiation dose by the use of carbon fiber cassettes].

    PubMed

    Hajek, P; Nowotny, R

    1984-03-01

    A new type of radiographic cassette, reinforced by PEEK-CFK is discussed. The amount of reduction of radiation dose by this cassette was evaluated by means of an experimental physical and clinical trial. Dose reduction may reach 30% depending on the type of examination and the organ studied. An increase of contrast of the radiographs could not be verified. This type of cassette can be recommended for routine clinical use. PMID:6423492

  4. Preliminary design review report for K Basin Dose Reduction Project

    SciTech Connect

    Blackburn, L.D.

    1996-01-01

    The strategy for reducing radiation dose, originating from radionuclides absorbed in the K East Basin concrete, is to raise the pool water level to provide additional shielding. This report documents a preliminary design review conducted to ensure that design approaches for cleaning/coating basin walls and modifying other basin components were appropriate. The conclusion of this review was that design documents presently conclusion of this review was that design documents presently completed or in process of modification are and acceptable basis for proceeding to complete the design.

  5. Automated testing data reduction computer program

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Kring, J.; Sullivan, T. L.

    1972-01-01

    The capability of a computer program which can be part of a larger computer program for a fully automated multiaxial testing facility is described. The program was designed to process test data from tubular or flat specimens made from isotropic or anistropic materials, including high modulus fiber composites. Data from a large number of strain gages and combinations of applied loads can be used. Options are provided for single element, 90-degree, rectangular or Delta rosettes, or any combinations of these types of strain gages. Options are provided for strain gage transverse sensitivities. The program outputs include: structural axes strains and stresses, initial and strain-dependent elastic constants, shift of principal strain direction with load, and local curvatures from back-to-back strain gages, and either Calcomp or microfilm plots. The computer program is described with respect to its flow chart, input/output, embedding or linking with other programs.

  6. Feasibility of normal tissue dose reduction in radiotherapy using low strength magnetic field

    PubMed Central

    Shin, Youngseob; Jung, In-Hye; Kwak, Jungwon

    2015-01-01

    Purpose Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field. Materials and Methods Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured. Results With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field. Conclusion RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field. PMID:26484306

  7. Patients with Fabry Disease after Enzyme Replacement Therapy Dose Reduction Versus Treatment Switch

    PubMed Central

    Krämer, Johannes; Duning, Thomas; Lenders, Malte; Canaan-Kühl, Sima; Krebs, Alice; González, Hans Guerrero; Sommer, Claudia; Üçeyler, Nurcan; Niemann, Markus; Störk, Stefan; Schelleckes, Michael; Reiermann, Stefanie; Stypmann, Jörg; Brand, Stefan-Martin; Wanner, Christoph; Brand, Eva

    2014-01-01

    Because of the shortage of agalsidase-beta in 2009, many patients with Fabry disease were treated with lower doses or were switched to agalsidase-alfa. This observational study assessed end-organ damage and clinical symptoms during dose reduction or switch to agalsidase-alfa. A total of 105 adult patients with Fabry disease who had received agalsidase-beta (1.0 mg/kg body weight) for ≥1 year were nonrandomly assigned to continue this treatment regimen (regular-dose group, n=38), receive a reduced dose of 0.3–0.5 mg/kg (dose-reduction group, n=29), or switch to 0.2 mg/kg agalsidase-alfa (switch group) and were followed prospectively for 1 year. We assessed clinical events (death, myocardial infarction, severe arrhythmia, stroke, progression to ESRD); changes in cardiac, renal, and neurologic function; and Fabry-related symptoms (neuropathic pain, hypohidrosis, diarrhea, and disease severity scores). Organ function and Fabry-related symptoms remained stable in the regular-dose group. In contrast, estimated GFR decreased by about 3 ml/min per 1.73 m2 (P=0.01) in the dose-reduction group, and the median albumin-to-creatinine ratio increased from 114 (0–606) mg/g to 216 (0–2062) mg/g (P=0.03) in the switch group. Furthermore, mean Mainz Severity Score Index scores and frequencies of pain attacks, chronic pain, gastrointestinal pain, and diarrhea increased significantly in the dose-reduction and switch groups. In conclusion, patients receiving regular agalsidase-beta dose had a stable disease course, but dose reduction led to worsening of renal function and symptoms. Switching to agalsidase-alfa is safe, but microalbuminuria may progress and Fabry-related symptoms may deteriorate. PMID:24556354

  8. Reduction of Radiation Doses to Patients and Staff During Endoscopic Retrograde Cholangiopancreatography

    PubMed Central

    Sulieman, Abdelmoneim; Paroutoglou, Georgios; Kapsoritakis, Andreas; Kapatenakis, Anargeyros; Potamianos, Spiros; Vlychou, Marianna; Theodorou, Kiki

    2011-01-01

    Background/Aim: Endoscopic retrograde cholangiopancreatography (ERCP) is associated with a considerable radiation exposure for patients and staff. While optimization of the radiation dose is recommended, few studies have been published. The purpose of this study has been to measure patient and staff radiation dose, to estimate the effective dose and radiation risk using digital fluoroscopic images. Entrance skin dose (ESD), organ and effective doses were estimated for patients and staff. Materials and Methods: Fifty-seven patients were studied using digital X-ray machine and thermoluminescent dosimeters (TLD) to measure ESD at different body sites. Organ and surface dose to specific radiosensitive organs was carried out. The mean, median, minimum, third quartile and the maximum values are presented due to the asymmetry in data distribution. Results: The mean ESD, exit and thyroid surface dose were estimated to be 75.6 mGy, 3.22 mGy and 0.80 mGy, respectively. The mean effective dose for both gastroenterologist and assistant is 0.01 mSv. The mean patient effective dose was 4.16 mSv, and the cancer risk per procedure was estimated to be 2 × 10-5 Conclusion: ERCP with fluoroscopic technique demonstrate improved dose reduction, compared to the conventional radiographic based technique, reducing the surface dose by a factor of 2, without compromising the diagnostic findings. The radiation absorbed doses to the different organs and effective doses are relatively low. PMID:21196649

  9. 76 FR 40320 - Risk Reduction Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-08

    ... requested public comment on a potential risk reduction rulemaking. See 75 FR 76345-76351, Dec. 8, 2010. A... plans to mitigate that risk. Each RRP is statutorily required to be supported by a risk analysis and a.... See 49 CFR 1.49(oo); 74 FR 26981 (June 5, 2009); see also 49 U.S.C. 103(g). Each railroad subject...

  10. Pollution reduction technology program for turboprop engines

    NASA Technical Reports Server (NTRS)

    Tomlinson, J. G.

    1977-01-01

    The reduction of CO, HC, and smoke emissions while maintaining acceptable NO(x) emissions without affecting fuel consumption, durability, maintainability, and safety was accomplished. Component combustor concept screening directed toward the demonstration of advanced combustor technology required to meet the EPA exhaust emissions standards for class P2 turboprop engines was covered. The combustion system for the Allison 501-D22A engine was used, and three combustor design concepts - reverse flow, prechamber, and staged fuel were evaluated.

  11. Method for inserting noise in digital mammography to simulate reduction in radiation dose

    NASA Astrophysics Data System (ADS)

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Vieira, Marcelo A. C.

    2015-03-01

    The quality of clinical x-ray images is closely related to the radiation dose used in the imaging study. The general principle for selecting the radiation is ALARA ("as low as reasonably achievable"). The practical optimization, however, remains challenging. It is well known that reducing the radiation dose increases the quantum noise, which could compromise the image quality. In order to conduct studies about dose reduction in mammography, it would be necessary to acquire repeated clinical images, from the same patient, with different dose levels. However, such practice would be unethical due to radiation related risks. One solution is to simulate the effects of dose reduction in clinical images. This work proposes a new method, based on the Anscombe transformation, which simulates dose reduction in digital mammography by inserting quantum noise into clinical mammograms acquired with the standard radiation dose. Thus, it is possible to simulate different levels of radiation doses without exposing the patient to new levels of radiation. Results showed that the achieved quality of simulated images generated with our method is the same as when using other methods found in the literature, with the novelty of using the Anscombe transformation for converting signal-independent Gaussian noise into signal-dependent quantum noise.

  12. Engineering risk reduction in satellite programs

    NASA Technical Reports Server (NTRS)

    Dean, E. S., Jr.

    1979-01-01

    Methods developed in planning and executing system safety engineering programs for Lockheed satellite integration contracts are presented. These procedures establish the applicable safety design criteria, document design compliance and assess the residual risks where non-compliant design is proposed, and provide for hazard analysis of system level test, handling and launch preparations. Operations hazard analysis identifies product protection and product liability hazards prior to the preparation of operational procedures and provides safety requirements for inclusion in them. The method developed for documenting all residual hazards for the attention of program management assures an acceptable minimum level of risk prior to program deployment. The results are significant for persons responsible for managing or engineering the deployment and production of complex high cost equipment under current product liability law and cost/time constraints, have a responsibility to minimize the possibility of an accident, and should have documentation to provide a defense in a product liability suit.

  13. THE NEXT GENERATION OF VMT REDUCTION PROGRAMS

    EPA Science Inventory

    This research is structured to provide a clear delineation of factors that influence trip chaining, identify levels of flexibility in commuter travel, present a market segmentation of commuters in terms of their flexibility levels, and estimate the reach of current programs. ...

  14. Objective assessment of image quality and dose reduction in CT iterative reconstruction

    SciTech Connect

    Vaishnav, J. Y. Jung, W. C.; Popescu, L. M.; Zeng, R.; Myers, K. J.

    2014-07-15

    Purpose: Iterative reconstruction (IR) algorithms have the potential to reduce radiation dose in CT diagnostic imaging. As these algorithms become available on the market, a standardizable method of quantifying the dose reduction that a particular IR method can achieve would be valuable. Such a method would assist manufacturers in making promotional claims about dose reduction, buyers in comparing different devices, physicists in independently validating the claims, and the United States Food and Drug Administration in regulating the labeling of CT devices. However, the nonlinear nature of commercially available IR algorithms poses challenges to objectively assessing image quality, a necessary step in establishing the amount of dose reduction that a given IR algorithm can achieve without compromising that image quality. This review paper seeks to consolidate information relevant to objectively assessing the quality of CT IR images, and thereby measuring the level of dose reduction that a given IR algorithm can achieve. Methods: The authors discuss task-based methods for assessing the quality of CT IR images and evaluating dose reduction. Results: The authors explain and review recent literature on signal detection and localization tasks in CT IR image quality assessment, the design of an appropriate phantom for these tasks, possible choices of observers (including human and model observers), and methods of evaluating observer performance. Conclusions: Standardizing the measurement of dose reduction is a problem of broad interest to the CT community and to public health. A necessary step in the process is the objective assessment of CT image quality, for which various task-based methods may be suitable. This paper attempts to consolidate recent literature that is relevant to the development and implementation of task-based methods for the assessment of CT IR image quality.

  15. Development of radiation dose reduction techniques for cadmium zinc telluride detectors in molecular breast imaging

    NASA Astrophysics Data System (ADS)

    O'Connor, Michael K.; Hruska, Carrie B.; Weinmann, Amanda; Manduca, Armando; Rhodes, Deborah J.

    2010-08-01

    Background: Molecular breast imaging (MBI) is a novel breast imaging technique that uses Cadmium Zinc Telluride (CZT) gamma cameras to detect the uptake of Tc-99m sestamibi in breast tumors. Current techniques employ an administered dose of 20-30 mCi Tc-99m, delivering an effective dose of 6.5-10 mSv to the body. This is ~ 5-10 times that of mammography. The goal of this study was to reduce the radiation dose by a factor of 5-10, while maintaining image quality. Methods: A total of 4 dose reduction schemes were evaluated - a) optimized collimation, b) improved utilization of the energy spectrum below the photopeak, c) adaptive geometric mean algorithm developed for combination of images from opposing detectors, and d) non local means filtering (NLMF) for noise reduction and image enhancement. Validation of the various schemes was performed using a breast phantom containing a variety of tumors and containing activity matched to that observed in clinical studies. Results: Development of tungsten collimators with holes matched to the CZT pixels yielded a 2.1-2.9 gain in system sensitivity. Improved utilization of the energy spectra yielded a 1.5-2.0 gain in sensitivity. Development of a modified geometric mean algorithm yielded a 1.4 reduction in image noise, while retaining contrast. Images of the breast phantom demonstrated that a factor of 5 reduction in dose was achieved. Additional refinements to the NLMF should enable an additional factor of 2 reduction in dose. Conclusion: Significant dose reduction in MBI to levels comparable to mammography can be achieved while maintaining image quality.

  16. Computed Tomography Angiography of Carotid Arteries and Vertebrobasilar System: A Simulation Study for Radiation Dose Reduction.

    PubMed

    Kramer, Manuel; Ellmann, Stephan; Allmendinger, Thomas; Eller, Achim; Kammerer, Ferdinand; May, Matthias S; Baigger, João F; Uder, Michael; Lell, Michael M

    2015-07-01

    Computed tomography angiography (CTA) of carotid arteries and vertebrobasilar system is a standardized procedure with excellent image quality, but radiation exposure remains a matter of concern. The aim of this study is to examine to what extent radiation dose can be lowered in relation to a standard protocol by simulating examinations with lower tube currents applying a dedicated software.Lower tube current was simulated by a dedicated noise insertion and reconstruction software (ReconCT). In a phantom study, true scans were performed with different dose protocols and compared to the results of simulated dose reductions of the same degree, respectively. In a patient study, 30 CTAs of supra-aortic vessels were reconstructed at a level of 100%, 75%, 50%, and 25% of the initial dose. Objective and subjective image analyses were performed.No significant noise differences between true scans and simulated scans of mimicked contrasted vessels were found. In the patient study, the quality scores of the 4 dose groups differed statistically significant; this difference vanished for the comparison of the 100% and 75% datasets after dichotomization into the categories of diagnostic and nondiagnostic image quality (P = .50).This study suggests an easy-to-implement method of simulating CTAs of carotid arteries and vertebrobasilar system with lower tube current for dose reduction by artificially adding noise to the original raw data. Lowering the radiation dose in a moderate extent to 75% of the original dose levels does not significantly alter the diagnostic image quality. PMID:26131822

  17. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations

    PubMed Central

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-01-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9 %. The dose reductions due to the bismuth shielding were 1.2–55 % depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 − 46 % for head and 41 − 55 % for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2–3 %. PMID:19959602

  18. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations.

    PubMed

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-03-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9%. The dose reductions due to the bismuth shielding were 1.2-55% depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 - 46% for head and 41 - 55% for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2-3%. PMID:19959602

  19. Dose Reduction versus Dose-interval Prolongation in Eribulin Mesilate Monotherapy in Patients with Metastatic Breast Cancer: A Retrospective Comparative Study.

    PubMed

    Sasaki, Toshinori; Oshima, Yumiko; Mishima, Etsuko; Ban, Akiko; Katsuragawa, Kenji; Nagamatsu, Hidetsugu; Yoshioka, Yuki; Tsukiyama, Ikuto; Hisada, Tatsuya; Itakura, Yukari; Mizutani, Mitsuhiro

    2016-07-01

    It is often necessary to modify the dose or schedule of eribulin mesilate (Eri) because of adverse events. Therefore, we retrospectively investigated the optimal approach for Eri dose adjustment and/or dosage interval adjustment. Patients who received Eri at the institutions affiliated with the Division of Oncology of the Aichi Prefectural Society of Hospital Pharmacists between July 2011 and November 2013 were enrolled in this study. We compared the group that underwent dose reduction without changes to their dosage interval (dose reduction group) with the group that had a change in their dosage interval (dose-interval prolongation group). The primary end-point was time to treatment failure (TTF), and the secondary end-points were overall survival (OS), overall response rate (ORR), clinical benefit rate (CBR), and adverse events. The TTF and OS of the dose reduction group were approximately two times longer than those of the dose-interval prolongation group. In addition, the dose reduction group had significantly improved ORR and CBR, which together indicate an antitumor effect (p=0.013 and 0.002, respectively). Although peripheral neuropathy occurred significantly more frequently in the patients in the dose reduction group (p=0.026), it was grade 1 and controllable in most of the cases. There were no differences in the occurrence of other adverse effects between the two groups. Therefore, we suggest that dose reduction with maintenance of the dosage interval is the preferred treatment approach in cases where Eri dose or schedule modification is necessary. PMID:27040459

  20. Method for simulating dose reduction in digital mammography using the Anscombe transformation

    PubMed Central

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Bakic, Predrag R.; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

    2016-01-01

    Purpose: This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. Methods: The method developed in this work consists of scaling a mammogram acquired at the standard radiation dose and adding signal-dependent noise. The algorithm accounts for specific issues relevant in digital mammography images, such as anisotropic noise, spatial variations in pixel gain, and the effect of dose reduction on the detective quantum efficiency. The scaling process takes into account the linearity of the system and the offset of the detector elements. The inserted noise is obtained by acquiring images of a flat-field phantom at the standard radiation dose and at the simulated dose. Using the Anscombe transformation, a relationship is created between the calculated noise mask and the scaled image, resulting in a clinical mammogram with the same noise and gray level characteristics as an image acquired at the lower-radiation dose. Results: The performance of the proposed algorithm was validated using real images acquired with an anthropomorphic breast phantom at four different doses, with five exposures for each dose and 256 nonoverlapping ROIs extracted from each image and with uniform images. The authors simulated lower-dose images and compared these with the real images. The authors evaluated the similarity between the normalized noise power spectrum (NNPS) and power spectrum (PS) of simulated images and real images acquired with the same dose. The maximum relative error was less than 2.5% for every ROI. The added noise was also evaluated by measuring the local variance in the real and simulated images. The relative average error for the local variance was smaller than 1%. Conclusions: A new method is proposed for simulating dose reduction in clinical mammograms. In this method, the dependency between image noise and image signal is addressed using a novel application of the Anscombe

  1. The NASA/AHS Rotorcraft Noise Reduction Program

    NASA Technical Reports Server (NTRS)

    Childress, Otis S., Jr.

    1988-01-01

    Research of the NASA/AHS noise reduction program is discussed, stressing work in four areas: noise prediction, testing and data base, noise reduction, and criteria development. A program called ROTONET has been developed, using a code structure divided into four main parts; main- and tail-rotor blade geometry, rotor performance, noise calculations, and noise propagation. Wind tunnel tests on individual rotors, and flight tests on a helicopter built specifically to generate a broadband main rotor noise data base have been conducted. In the field of noise reduction, researchers have performed analytical evaluations of low noise rotor concepts, and small-scale wind tunnel evaluations of noise reduction concepts. Under the supervision of the FAA, the program in conducting tests to develop criteria for helicopters and heliports.

  2. Is radiation dose reduction the right answer for HPV-positive head and neck cancer?

    PubMed Central

    Kimple, Randall J.; Harari, Paul M.

    2013-01-01

    Patients with head and neck squamous cell carcinoma (HNC) related to human papillomavirus (HPV) represent a growing and distinct patient cohort with unique molecular and epidemiologic characteristics. These patients have markedly improved survival outcomes compared to those with traditional HNC, leading some to advocate for treatment dose reduction. In this article, we review ongoing clinical trials investigating several ways to reduce therapeutic intensity for patients with HPV-positive HNC, discuss the risks and benefits associated with these trials, and summarize the data underlying the advancement of dose reduction trials for patients with HPV-positive HNC. PMID:24134946

  3. Is radiation dose reduction the right answer for HPV-positive head and neck cancer?

    PubMed

    Kimple, Randall J; Harari, Paul M

    2014-06-01

    Patients with head and neck squamous cell carcinoma (HNC) related to human papillomavirus (HPV) represent a growing and distinct patient cohort with unique molecular and epidemiologic characteristics. These patients have markedly improved survival outcomes compared to those with traditional HNC, leading some to advocate for treatment dose reduction. In this article, we review ongoing clinical trials investigating several ways to reduce therapeutic intensity for patients with HPV-positive HNC, discuss the risks and benefits associated with these trials, and summarize the data underlying the advancement of dose reduction trials for patients with HPV-positive HNC. PMID:24134946

  4. Computer program developed for flowsheet calculations and process data reduction

    NASA Technical Reports Server (NTRS)

    Alfredson, P. G.; Anastasia, L. J.; Knudsen, I. E.; Koppel, L. B.; Vogel, G. J.

    1969-01-01

    Computer program PACER-65, is used for flowsheet calculations and easily adapted to process data reduction. Each unit, vessel, meter, and processing operation in the overall flowsheet is represented by a separate subroutine, which the program calls in the order required to complete an overall flowsheet calculation.

  5. Error Reduction Program. [combustor performance evaluation codes

    NASA Technical Reports Server (NTRS)

    Syed, S. A.; Chiappetta, L. M.; Gosman, A. D.

    1985-01-01

    The details of a study to select, incorporate and evaluate the best available finite difference scheme to reduce numerical error in combustor performance evaluation codes are described. The combustor performance computer programs chosen were the two dimensional and three dimensional versions of Pratt & Whitney's TEACH code. The criteria used to select schemes required that the difference equations mirror the properties of the governing differential equation, be more accurate than the current hybrid difference scheme, be stable and economical, be compatible with TEACH codes, use only modest amounts of additional storage, and be relatively simple. The methods of assessment used in the selection process consisted of examination of the difference equation, evaluation of the properties of the coefficient matrix, Taylor series analysis, and performance on model problems. Five schemes from the literature and three schemes developed during the course of the study were evaluated. This effort resulted in the incorporation of a scheme in 3D-TEACH which is usuallly more accurate than the hybrid differencing method and never less accurate.

  6. Cooperative Threat Reduction: Cooperation Threat Reduction Program Liquid Propellant Disposition Project

    NASA Astrophysics Data System (ADS)

    2002-09-01

    This audit is one in a series of audits the Deputy Secretary of Defense requested. As part of the Cooperative Threat Reduction (CTR) Program, DoD agreed to assist the Russian Federation in disposing of its liquid rocket propellant. Public Law 102-228 (section 2551 NOTE, title 22, United States Code), the Soviet Nuclear Threat Reduction Act of 1991 designates DoD as the executive agent for the CTR Program. Specific objectives of the act are to destroy chemical, nuclear, and other weapons; transport, store, disable, and safeguard weapons in connection with their destruction; and establish verifiable safeguards against proliferation of weapons of mass destruction. The Office of the Assistant Secretary of Defense (International Security Policy), under the Office of the Under Secretary of Defense for Policy, develops, coordinates, and oversees implementation of policy for the CTR Program. The CTR Directorate, Defense Threat Reduction Agency operates the program.

  7. SU-E-P-03: Implementing a Low Dose Lung Screening CT Program Meeting Regulatory Requirements

    SciTech Connect

    LaFrance, M; Marsh, S; O'Donnell, G

    2014-06-01

    Purpose: To provide information pertaining to IROC Houston QA Center's (RPC) credentialing process for institutions participating in NCI-sponsored clinical trials. Purpose: Provide guidance to the Radiology Departments with the intent of implementing a Low Dose CT Screening Program using different CT Scanners with multiple techniques within the framework of the required state regulations. Method: State Requirements for the purpose of implementing a Low Dose CT Lung Protocol required working with the Radiology and Pulmonary Department in setting up a Low Dose Screening Protocol designed to reduce the radiation burden to the patients enrolled. Radiation dose measurements (CTDIvol) for various CT manufacturers (Siemens16, Siemens 64, Philips 64, and Neusoft128) for three different weight based protocols. All scans were reviewed by the Radiologist. Prior to starting a low dose lung screening protocol, information had to be submitted to the state for approval. Performing a Healing Arts protocol requires extensive information. This not only includes name and address of the applicant but a detailed description of the disease, the x-ray examination and the population to be examined. The unit had to be tested by a qualified expert using the technique charts. The credentials of all the operators, the supervisors and the Radiologists had to be submitted to the state. Results: All the appropriate documentation was sent to the state for review. The measured results between the Low Dose Protocol versus the default Adult Chest Protocol showed that there was a dose reduction of 65% for small (100-150 lb.) patient, 75% for the Medium patient (151-250 lbs.), and a 55% reduction for the Large patient ( over 250 lbs.). Conclusion: Measured results indicated that the Low Dose Protocol indeed lowered the screening patient's radiation dose and the institution was able to submit the protocol to the State's regulators.

  8. Three-dimensional quantitative dose reduction analysis in MammoSite balloon by Monte Carlo calculations.

    PubMed

    Zhang, Zhengdong; Parsai, E Ishmael; Feldmeier, John J

    2007-01-01

    Current treatment planning systems (TPSs) for partial breast irradiation using the MammoSite brachytherapy applicator (Cytyc Corporation, Marlborough, MA) often neglect the effect of inhomogeneity, leading to potential inaccuracies in dose distributions. Previous publications either have studied only a planar dose perturbation along the bisector of the source or have paid little attention to the anisotropy effect of the system. In the present study, we investigated the attenuation-corrected radial dose and anisotropy functions in a form parallel to the updated American Association of Physicists in Medicine TG-43 formalism. This work quantitatively delineates the inaccuracies in dose distributions in three-dimensional space. Monte Carlo N-particle transport code simulations in coupled photon-electron transport were used to quantify the changes in dose deposition and distribution caused by the increased attenuation coefficient of iodine-based contrast solution. The source geometry was that of the VariSource wire model VS2000 (Varian Medical Systems, Palo Alto, CA). The concentration of the iodine-based solution was varied from 5% to 25% by volume, a range recommended by the balloon's manufacturer. Balloon diameters of 4, 5, and 6 cm were simulated. Dose rates at the typical prescription line (1 cm away from the balloon surface) were determined for various polar angles. The computations showed that the dose rate reduction throughout the entire region of interest ranged from 0.64% for the smallest balloon diameter and contrast concentration to 6.17% for the largest balloon diameter and contrast concentration. The corrected radial dose function has a predominant influence on dose reduction, but the corrected anisotropy functions explain only the effect at the MammoSite system poles. By applying the corrected radial dose and anisotropy functions to TPSs, the attenuation effect can be reduced to the minimum. PMID:18449153

  9. Reducing Radiation Dose in Coronary Angiography and Angioplasty Using Image Noise Reduction Technology.

    PubMed

    Kastrati, Mirlind; Langenbrink, Lukas; Piatkowski, Michal; Michaelsen, Jochen; Reimann, Doris; Hoffmann, Rainer

    2016-08-01

    This study sought to quantitatively evaluate the reduction of radiation dose in coronary angiography and angioplasty with the use of image noise reduction technology in a routine clinical setting. Radiation dose data from consecutive 605 coronary procedures (397 consecutive coronary angiograms and 208 consecutive coronary interventions) performed from October 2014 to April 2015 on a coronary angiography system with noise reduction technology (Allura Clarity IQ) were collected. For comparison, radiation dose data from consecutive 695 coronary procedures (435 coronary angiograms and 260 coronary interventions) performed on a conventional coronary angiography system from October 2013 to April 2014 were evaluated. Patient radiation dosage was evaluated based on the cumulative dose area product. Operators and operator practice did not change between the 2 evaluated periods. Patient characteristics were collected to evaluate similarity of patient groups. Image quality was evaluated on a 5-grade scale in 30 patients of each group. There were no significant differences between the 2 evaluated groups in gender, age, weight, and fluoroscopy time (6.8 ± 6.1 vs 6.9 ± 6.3 minutes, not significant). The dose area product was reduced from 3195 ± 2359 to 983 ± 972 cGycm(2) (65%, p <0.001) in coronary angiograms and from 7123 ± 4551 to 2431 ± 1788 cGycm(2) (69%, p <0.001) in coronary interventions using the new noise reduction technology. Image quality was graded as similar between the evaluated systems (4.0 ± 0.7 vs 4.2 ± 0.6, not significant). In conclusion, a new x-ray technology with image noise reduction algorithm provides a substantial reduction in radiation exposure without the need to prolong the procedure or fluoroscopy time. PMID:27344273

  10. Potential of combining iterative reconstruction with noise efficient detector design: aggressive dose reduction in head CT

    PubMed Central

    Bender, B; Schabel, C; Fenchel, M; Ernemann, U; Korn, A

    2015-01-01

    Objective: With further increase of CT numbers and their dominant contribution to medical exposure, there is a recent quest for more effective dose control. While reintroduction of iterative reconstruction (IR) has proved its potential in many applications, a novel focus is placed on more noise efficient detectors. Our purpose was to assess the potential of IR in combination with an integrated circuit detector (ICD) for aggressive dose reduction in head CT. Methods: Non-contrast low-dose head CT [190 mAs; weighted volume CT dose index (CTDIvol), 33.2 mGy] was performed in 50 consecutive patients, using a new noise efficient detector and IR. Images were assessed in terms of quantitative and qualitative image quality and compared with standard dose acquisitions (320 mAs; CTDIvol, 59.7 mGy) using a conventional detector and filtered back projection. Results: By combining ICD and IR in low-dose examinations, the signal to noise was improved by about 13% above the baseline level in the standard-dose control group. Both, contrast-to-noise ratio (2.02 ± 0.6 vs 1.88 ± 0.4; p = 0.18) and objective measurements of image sharpness (695 ± 84 vs 705 ± 151 change in Hounsfield units per pixel; p = 0.79) were fully preserved in the low-dose group. Likewise, there was no significant difference in the grading of several subjective image quality parameters when both noise-reducing strategies were used in low-dose examinations. Conclusion: Combination of noise efficient detector with IR allows for meaningful dose reduction in head CT without compromise of standard image quality. Advances in knowledge: Our study demonstrates the feasibility of almost 50% dose reduction in head CT dose (1.1 mSv per scan) through combination of novel dose-reducing strategies. PMID:25827204

  11. Limits to dose reduction from iterative reconstruction and the effect of through-slice blurring

    NASA Astrophysics Data System (ADS)

    Hsieh, Scott S.; Pelc, Norbert J.

    2016-03-01

    Iterative reconstruction methods have become very popular and show the potential to reduce dose. We present a limit to the maximum dose reduction possible with new reconstruction algorithms obtained by analyzing the information content of the raw data, assuming the reconstruction algorithm does not have a priori knowledge about the object or correlations between pixels. This limit applies to the task of estimating the density of a lesion embedded in a known background object, where the shape of the lesion is known but its density is not. Under these conditions, the density of the lesion can be estimated directly from the raw data in an optimal manner. This optimal estimate will meet or outperform the performance of any reconstruction method operating on the raw data, under the condition that the reconstruction method does not introduce a priori information. The raw data bound can be compared to the lesion density estimate from FBP in order to produce a limit on the dose reduction possible from new reconstruction algorithms. The possible dose reduction from iterative reconstruction varies with the object, but for a lesion embedded in the center of a water cylinder, it is less than 40%. Additionally, comparisons between iterative reconstruction and filtered backprojection are sometimes confounded by the effect of through-slice blurring in the iterative reconstruction. We analyzed the magnitude of the variance reduction brought about by through-slice blurring on scanners from two different vendors and found it to range between 11% and 48%.

  12. Pilot Study on Image Quality and Radiation Dose of CT Colonography with Adaptive Iterative Dose Reduction Three-Dimensional

    PubMed Central

    Shen, Hesong; Liang, Dan; Luo, Mingyue; Duan, Chaijie; Cai, Wenli; Zhu, Shanshan; Qiu, Jianping; Li, Wenru

    2015-01-01

    Objective To investigate image quality and radiation dose of CT colonography (CTC) with adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Ten segments of porcine colon phantom were collected, and 30 pedunculate polyps with diameters ranging from 1 to 15 mm were simulated on each segment. Image data were acquired with tube voltage of 120 kVp, and current doses of 10 mAs, 20 mAs, 30 mAs, 40 mAs, 50 mAs, respectively. CTC images were reconstructed using filtered back projection (FBP) and AIDR3D. Two radiologists blindly evaluated image quality. Quantitative evaluation of image quality included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Qualitative image quality was evaluated with a five-score scale. Radiation dose was calculated based on dose-length product. Ten volunteers were examined supine 50 mAs with FBP and prone 20 mAs with AIDR3D, and image qualities were assessed. Paired t test was performed for statistical analysis. Results For 20 mAs with AIDR3D and 50 mAs with FBP, image noise, SNRs and CNRs were (16.4 ± 1.6) HU vs. (16.8 ± 2.6) HU, 1.9 ± 0.2 vs. 1.9 ± 0.4, and 62.3 ± 6.8 vs. 62.0 ± 6.2, respectively; qualitative image quality scores were 4.1 and 4.3, respectively; their differences were all not statistically significant. Compared with 50 mAs with FBP, radiation dose (1.62 mSv) of 20 mAs with AIDR3D was decreased by 60.0%. There was no statistically significant difference in image noise, SNRs, CNRs and qualitative image quality scores between prone 20 mAs with AIDR3D and supine 50 mAs with FBP in 10 volunteers, the former reduced radiation dose by 61.1%. Conclusion Image quality of CTC using 20 mAs with AIDR3D could be comparable to standard 50 mAs with FBP, radiation dose of the former reduced by about 60.0% and was only 1.62 mSv. PMID:25635839

  13. Evaluation of the potential in radiation dose reduction for full-field digital mammography

    NASA Astrophysics Data System (ADS)

    Kasch, Kay-Uwe; Moftah, Belal A.

    2008-01-01

    This study evaluates the image quality for different radiation doses in full-field digital mammography (FFDM). The potential of dose reductions is evaluated for both, the transition from screen-film mammography (SFM) to FFDM as well as within FFDM due to the optimization of exposure parameters. Exposures of a 4.5 cm breast phantom rendering different contrasts as well as bar patterns were made using a FFDM system (GE Senographe 2000D). For different kVp and mAs settings as well as different target/filter combinations chosen for the above exposures, average glandular dose (AGD), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and modulation transfer function (MTF) were determined. To benchmark the results, relative change of AGD was evaluated against SNR, CNR and MTF. Eventually, the results were normalized to AGD's rendered by settings typically used in today's clinical routine. For standard settings (automatic mode), both FFDM and SFM deliver approximately the same AGD of about 2.2 mGy. From that, AGD reduction can be substantial in FFDM if only SNR and high contrast CNR are considered. In this case, reduction of up to 40% can be achieved in a wide kVp range if switching from the standard target/filter combination Mo/Rh to Rh/Rh. However, if low contrast CNR is to remain unchanged, dose reduction is practically impossible. The change of peak voltage and target/filter material had no influence on MTF. Assuming current CNR requirements as standards, significant dose reduction in FFDM cannot be achieved. Only by compromising low contrast CNR levels AGD of up to 40% can be saved at current standards of SNR and high contrast CNR.

  14. High-dose secondary calibration laboratory accreditation program

    SciTech Connect

    Humphreys, J.C.

    1993-12-31

    There is a need for high-dose secondary calibration laboratories to serve the multi-billion dollar radiation processing industry. This need is driven by the desires of industry for less costly calibrations and faster calibration-cycle response time. Services needed include calibration irradiations of routine processing dosimeters and the supply of reference standard transfer dosimeters for irradiation in the production processing facility. In order to provide measurement quality assurance and to demonstrate consistency with national standards, the high-dose secondary laboratories would be accredited by means of an expansion of an existing National Voluntary Laboratory Accreditation Program. A laboratory performance criteria document is under development to implement the new program.

  15. Dose reduction in LDR brachytherapy by implanted prostate gold fiducial markers

    SciTech Connect

    Landry, Guillaume; Reniers, Brigitte; Lutgens, Ludy; Murrer, Lars; Afsharpour, Hossein; Haas-Kock, Danielle de; Visser, Peter; Gils, Francis van; Verhaegen, Frank

    2012-03-15

    Purpose: The dosimetric impact of gold fiducial markers (FM) implanted prior to external beam radiotherapy of prostate cancer on low dose rate (LDR) brachytherapy seed implants performed in the context of combined therapy was investigated. Methods: A virtual water phantom was designed containing a single FM. Single and multi source scenarios were investigated by performing Monte Carlo dose calculations, along with the influence of varying orientation and distance of the FM with respect to the sources. Three prostate cancer patients treated with LDR brachytherapy for a recurrence following external beam radiotherapy with implanted FM were studied as surrogate cases to combined therapy. FM and brachytherapy seeds were identified on post implant CT scans and Monte Carlo dose calculations were performed with and without FM. The dosimetric impact of the FM was evaluated by quantifying the amplitude of dose shadows and the volume of cold spots. D{sub 90} was reported based on the post implant CT prostate contour. Results: Large shadows are observed in the single source-FM scenarios. As expected from geometric considerations, the shadows are dependent on source-FM distance and orientation. Large dose reductions are observed at the distal side of FM, while at the proximal side a dose enhancement is observed. In multisource scenarios, the importance of shadows appears mitigated, although FM at the periphery of the seed distribution caused underdosage (dose). In clinical cases, the FM reduced the dose to some voxels by up to 50% and generated shadows with extents of the order of 4 mm. Within the prostate contour, cold spots (<95% prescription dose) of the order of 20 mm{sup 3} were observed. D{sub 90} proved insensitive to the presence of FM for the cases selected. Conclusions: There is a major local impact of FM present in LDR brachytherapy seed implant dose distributions. Therefore, reduced tumor control could be expected from FM implanted in tumors, although

  16. Feasibility study of dose reduction in digital breast tomosynthesis using non-local denoising algorithms

    NASA Astrophysics Data System (ADS)

    Vieira, Marcelo A. C.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Borges, Lucas R.; Bakic, Predrag R.; Barufaldi, Bruno; Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2015-03-01

    The main purpose of this work is to study the ability of denoising algorithms to reduce the radiation dose in Digital Breast Tomosynthesis (DBT) examinations. Clinical use of DBT is normally performed in "combo-mode", in which, in addition to DBT projections, a 2D mammogram is taken with the standard radiation dose. As a result, patients have been exposed to radiation doses higher than used in digital mammography. Thus, efforts to reduce the radiation dose in DBT examinations are of great interest. However, a decrease in dose leads to an increased quantum noise level, and related decrease in image quality. This work is aimed at addressing this problem by the use of denoising techniques, which could allow for dose reduction while keeping the image quality acceptable. We have studied two "state of the art" denoising techniques for filtering the quantum noise due to the reduced dose in DBT projections: Non-local Means (NLM) and Block-matching 3D (BM3D). We acquired DBT projections at different dose levels of an anthropomorphic physical breast phantom with inserted simulated microcalcifications. Then, we found the optimal filtering parameters where the denoising algorithms are capable of recovering the quality from the DBT images acquired with the standard radiation dose. Results using objective image quality assessment metrics showed that BM3D algorithm achieved better noise adjustment (mean difference in peak signal to noise ratio < 0.1dB) and less blurring (mean difference in image sharpness ~ 6%) than the NLM for the projections acquired with lower radiation doses.

  17. Treating Technophobia: A Longitudinal Evaluation of the Computerphobia Reduction Program.

    ERIC Educational Resources Information Center

    Rosen, Larry D.; And Others

    1993-01-01

    Describes a longitudinal evaluation of the five-week Computerphobia Reduction Program designed to reduce anxiety in the use of computers. Discusses methodology, evaluation measures, selection of clients, therapies offered, and results, which showed the intervention strategies to be successful in reducing computer anxiety over the long term. (28…

  18. Special Diabetes Program for Indians: Retention in Cardiovascular Risk Reduction

    ERIC Educational Resources Information Center

    Manson, Spero M.; Jiang, Luohua; Zhang, Lijing; Beals, Janette; Acton, Kelly J.; Roubideaux, Yvette

    2011-01-01

    Purpose: This study examined the associations between participant and site characteristics and retention in a multisite cardiovascular disease risk reduction project. Design and Methods: Data were derived from the Special Diabetes Program for Indians Healthy Heart Demonstration Project, an intervention to reduce cardiovascular risk among American…

  19. An evaluation of a sitter reduction program intervention.

    PubMed

    Spiva, LeeAnna; Feiner, Therese; Jones, Darcia; Hunter, Donna; Petefish, Jayne; VanBrackle, Lewis

    2012-01-01

    Hospitals use sitters as an alternative to reduce patient falls. The purpose of the study was to evaluate the effectiveness of a sitter reduction program by examining the differences between sitter use and falls in an acute care hospital. Findings indicate that a significant decrease in sitter use and falls remained constant. Reducing sitter use is possible without significantly increasing fall rates. PMID:22692004

  20. Ramsey County commercial, industrial, institutional waste reduction and recycling program

    SciTech Connect

    Lyman-Onkka, C.

    1995-09-01

    The Ramsey County Commercial, Industrial, Institutional Waste Reduction and Recycling Program was developed (1) to raise awareness of waste reduction and recycling opportunities for businesses, (2) to make information available to businesses, (3) to provide technical assistance to small and medium sized businesses on waste reduction and recycling, and (4) to raise awareness of Ramsey County as a technical resource. Ramsey County was founded in 1849 and is named for Alexander Ramsey, the first governor of the Minnesota Territory. Ramsey County is the smallest, most urban of all 87 counties in Minnesota. With 170 square miles and a 1990 population of 485,000, Ramsey has the most people per square mile of any county in Minnesota. There are 19 cities within the County, the largest is Saint Paul with a 1990 population of 272,000. There are no unincorporated areas in Ramsey County. This report describes the efforts directed towards raising the awareness of the county waste management, recycling program.

  1. Dose reduction and image quality optimizations in CT of pediatric and adult patients: phantom studies

    NASA Astrophysics Data System (ADS)

    Jeon, P.-H.; Lee, C.-L.; Kim, D.-H.; Lee, Y.-J.; Jeon, S.-S.; Kim, H.-J.

    2014-03-01

    Multi-detector computed tomography (MDCT) can be used to easily and rapidly perform numerous acquisitions, possibly leading to a marked increase in the radiation dose to individual patients. Technical options dedicated to automatically adjusting the acquisition parameters according to the patient's size are of specific interest in pediatric radiology. A constant tube potential reduction can be achieved for adults and children, while maintaining a constant detector energy fluence. To evaluate radiation dose, the weighted CT dose index (CTDIw) was calculated based on the CT dose index (CTDI) measured using an ion chamber, and image noise and image contrast were measured from a scanned image to evaluate image quality. The dose-weighted contrast-to-noise ratio (CNRD) was calculated from the radiation dose, image noise, and image contrast measured from a scanned image. The noise derivative (ND) is a quality index for dose efficiency. X-ray spectra with tube voltages ranging from 80 to 140 kVp were used to compute the average photon energy. Image contrast and the corresponding contrast-to-noise ratio (CNR) were determined for lesions of soft tissue, muscle, bone, and iodine relative to a uniform water background, as the iodine contrast increases at lower energy (i.e., k-edge of iodine is 33 keV closer to the beam energy) using mixed water-iodine contrast normalization (water 0, iodine 25, 100, 200, and 1000 HU, respectively). The proposed values correspond to high quality images and can be reduced if only high-contrast organs are assessed. The potential benefit of lowering the tube voltage is an improved CNRD, resulting in a lower radiation dose and optimization of image quality. Adjusting the tube potential in abdominal CT would be useful in current pediatric radiography, where the choice of X-ray techniques generally takes into account the size of the patient as well as the need to balance the conflicting requirements of diagnostic image quality and radiation dose

  2. Experimental study on photon-beam peripheral doses, their components and some possibilities for their reduction

    NASA Astrophysics Data System (ADS)

    Chofor, Ndimofor; Harder, Dietrich; Rühmann, Antje; Willborn, Kay C.; Wiezorek, Tilo; Poppe, Björn

    2010-07-01

    The component analysis of the peripheral doses produced at typical accelerators such as the Siemens Primus 6/15 is regarded as an approach enabling technical strategies towards the reduction of second malignancies associated with photon beam radiotherapy. Suitable phantom and detector arrangements have been applied to show that the unavoidable peripheral dose contribution due to photon scattering from the directly irradiated part of the body or phantom does not constitute the entirety of the peripheral doses. Rather, there are peripheral dose contributions due to beam head leakage and to extrafocal radiation which can be regarded as partly avoidable. Simple methods of reducing beam head leakage from the Siemens Primus 6/15 linac are, for the crossplane direction, to install a pair of adjustable shielding blocks in the accessory holder and, for the inplane direction, to close all out-of-field leaf pairs of the multileaf collimator via the treatment planning system software. The relative efficiency of these shielding measures is largest in the case of small unavoidable dose contributions, i.e. for small fields and small depths. Methods of avoiding doses coming from extrafocal radiation are also envisaged for future research.

  3. Development of mammography system using CdTe photon counting detector for the exposure dose reduction

    NASA Astrophysics Data System (ADS)

    Maruyama, Sho; Niwa, Naoko; Yamazaki, Misaki; Yamakawa, Tsutomu; Nagano, Tatsuya; Kodera, Yoshie

    2014-03-01

    We propose a new mammography system using a cadmium telluride (CdTe) photon-counting detector for exposure dose reduction. In contrast to conventional mammography, this system uses high-energy X-rays. This study evaluates the usefulness of this system in terms of the absorbed dose distribution and contrast-to-noise ratio (CNR) at acrylic step using a Monte Carlo simulation. In addition, we created a prototype system that uses a CdTe detector and automatic movement stage. For various conditions, we measured the properties and evaluated the quality of images produced by the system. The simulation result for a tube voltage of 40 kV and tungsten/barium (W/Ba) as a target/filter shows that the surface dose was reduced more than 60% compared to that under conventional conditions. The CNR of our proposal system also became higher than that under conventional conditions. The point at which the CNRs coincide for 4 cm polymethyl methacrylate (PMMA) at the 2-mm-thick step corresponds to a dose reduction of 30%, and these differences increased with increasing phantom thickness. To improve the image quality, we determined the problematic aspects of the scanning system. The results of this study indicate that, by using a higher X-ray energy than in conventional mammography, it is possible to obtain a significant exposure dose reduction without loss of image quality. Further, the image quality of the prototype system can be improved by optimizing the balance between the shift-and-add operation and the output of the X-ray tube. In future work, we will further examine these improvement points.

  4. Data base on dose reduction research projects for nuclear power plants. Volume 5

    SciTech Connect

    Khan, T.A.; Yu, C.K.; Roecklein, A.K.

    1994-05-01

    This is the fifth volume in a series of reports that provide information on dose reduction research and health physics technology or nuclear power plants. The information is taken from two of several databases maintained by Brookhaven National Laboratory`s ALARA Center for the Nuclear Regulatory Commission. The research section of the report covers dose reduction projects that are in the experimental or developmental phase. It includes topics such as steam generator degradation, decontamination, robotics, improvements in reactor materials, and inspection techniques. The section on health physics technology discusses dose reduction efforts that are in place or in the process of being implemented at nuclear power plants. A total of 105 new or updated projects are described. All project abstracts from this report are available to nuclear industry professionals with access to a fax machine through the ACEFAX system or a computer with a modem and the proper communications software through the ACE system. Detailed descriptions of how to access all the databases electronically are in the appendices of the report.

  5. Reducing Patient Radiation Dose With Image Noise Reduction Technology in Transcatheter Aortic Valve Procedures.

    PubMed

    Lauterbach, Michael; Hauptmann, Karl Eugen

    2016-03-01

    X-ray radiation exposure is of great concern for patients undergoing structural heart interventions. In addition, a larger group of medical staff is required and exposed to radiation compared with percutaneous coronary interventions. This study aimed at quantifying radiation dose reduction with implementation of specific image noise reduction technology (NRT) in transcatheter aortic valve implantation (TAVI) procedures. We retrospectively analyzed 104 consecutive patients with TAVI procedures, 52 patients before and 52 after optimization of x-ray radiation chain, and implementation of NRT. Patients with 1-step TAVI and complex coronary intervention, or complex TAVI procedures, were excluded. Before the procedure, all patients received a multislice computed tomography scan, which was used to size aortic annulus, select the optimal implantation plane, valve type and size, and guide valve implantation using a software tool. Air kerma and kerma-area product were compared in both groups to determine patient radiation dose reduction. Baseline parameters, co-morbidity, or procedural data were comparable between groups. Mean kerma-area product was significantly lower (p <0.001) in the NRT group compared with the standard group (60 ± 39 vs 203 ± 106 Gy × cm(2), p <0.001), which corresponds to a reduction of 70%. Mean air kerma was reduced by 64% (494 ± 360 vs 1,355 ± 657 mGy, p <0.001). In conclusion, using optimized x-ray chain combined with specific image noise reduction technology has the potential to significantly reduce by 2/3 radiation dose in standard TAVI procedures without worsening image quality or prolonging procedure time. PMID:26742472

  6. The reduction of dose in paediatric panoramic radiography: the impact of collimator height and programme selection

    PubMed Central

    Safi, H; Maddison, S M

    2015-01-01

    Objectives: The aim of this work was to estimate the doses to radiosensitive organs in the head of a young child undergoing panoramic radiography and to establish the effectiveness of a short collimator in reducing dose. Methods: Thermoluminescent dosemeters were used in a paediatric head phantom to simulate an examination on a 5-year-old child. The panoramic system used was an Instrumentarium OP200 D (Instrumentarium Dental, Tuusula, Finland). The collimator height options were 110 and 140 mm. Organ doses were measured using exposure programmes intended for use with adult and child size heads. The performance of the automatic exposure control (AEC) system was also assessed. Results: The short collimator reduced the dose to the brain and the eyes by 57% and 41%, respectively. The dose to the submandibular and sublingual glands increased by 32% and 20%, respectively, when using a programme with a narrower focal trough intended for a small jaw. The effective dose measured with the short collimator and paediatric programme was 7.7 μSv. The dose to the lens of the eye was 17 μGy. When used, the AEC system produced some asymmetry in the dose distribution across the head. Conclusions: Panoramic systems when used to frequently image children should have programmes specifically designed for imaging small heads. There should be a shorter collimator available and programmes that deliver a reduced exposure time and allow reduction of tube current. Programme selection should also provide flexibility for focal trough size, shape and position to match the smaller head size. PMID:25352427

  7. Direct detector radiography versus dual reading computed radiography: feasibility of dose reduction in chest radiography.

    PubMed

    Gruber, Michael; Uffmann, Martin; Weber, Michael; Prokop, Mathias; Balassy, Csilla; Schaefer-Prokop, Cornelia

    2006-07-01

    The image quality of dual-reading computed radiography and dose-reduced direct radiography of the chest was compared in a clinical setting. The study group consisted of 50 patients that underwent three posteroanterior chest radiographs within minutes, one image obtained with a dual read-out computed radiography system (CR; Fuji 5501) at regular dose and two images with a flat panel direct detector unit (DR; Diagnost, Philips). The DR images were obtained with the same and with 50% of the dose used for the CR images. Images were evaluated in a blinded side-by-side comparison. Eight radiologists ranked the visually perceivable difference in image quality using a three-point scale. Then, three radiologists scored the visibility of anatomic landmarks in low and high attenuation areas and image noise. Statistical analysis was based on Friedman tests and Wilcoxon rank sum tests at a significance level of P<0.05. DR was judged superior to CR for the delineation of structures in high attenuation areas of the mediastinum even when obtained with 50% less dose (P<0.001). The visibility of most pulmonary structures was judged equivalent with both techniques, regardless of acquisition dose and speed level. Scores for image noise were lower for DR compared with CR, with the exception of DR obtained at a reduced dose. Thus, in this clinical preference study, DR was equivalent or even superior to the most modern dual read-out CR, even when obtained with 50% dose. A further dose reduction does not appear to be feasible for DR without significant loss of image quality. PMID:16404566

  8. On the Need to Compensate for Edema-Induced Dose Reductions in Preplanned {sup 131}Cs Prostate Brachytherapy

    SciTech Connect

    Chen, Z. Jay Deng Jun; Roberts, Kenneth; Nath, Ravinder

    2008-01-01

    Purpose: Surgical trauma-induced edema and its protracted resolution can lead to significant dose reductions in preplanned {sup 131}Cs prostate brachytherapy. The purpose of this work was to examine whether these dose reductions should be actively compensated for and to estimate the magnitude of the additional irradiation needed for dose compensation. Methods and Materials: The quantitative edema resolution characteristics observed by Waterman et al. were used to examine the physical and radiobiologic effects of prostate edema in preplanned {sup 131}Cs implants. The need for dose compensation was assessed using the dose responses observed in {sup 125}I and {sup 103}Pd prostate implants. The biologically effective dose, calculated with full consideration of edema evolution, was used to estimate the additional irradiation needed for dose compensation. Results: We found that the edema-induced dose reduction in preplanned {sup 131}Cs implants could easily exceed 10% of the prescription dose for implants with moderate or large edema. These dose reductions could lead to a >10% reduction in the biochemical recurrence-free survival for individual patients if the effect of edema was ignored. For a prescribed dose of 120 Gy, the number of 2-Gy external beam fractions needed to compensate for a 5%, 10%, 15%, 20%, and 25% edema-induced dose reduction would be one, four, six, seven, and nine, respectively, for prostate cancer with a median potential doubling time of 42 days. The required additional irradiation increased for fast-growing tumors and/or those less efficient in sublethal damage repair. Conclusion: Compensation of edema-induced dose reductions in preplanned {sup 131}Cs prostate brachytherapy should be actively considered for those implants with moderate or large edema.

  9. On the need to compensate edema-induced dose reductions in pre-planned 131Cs prostate brachytherapy

    PubMed Central

    Chen, Z. Jay; Deng, Jun; Roberts, Kenneth; Nath, Ravinder

    2008-01-01

    Purpose Surgical-trauma-induced edema and its protracted resolution can lead to significant dose reduction in pre-planned 131Cs prostate brachytherapy. The purpose of this work was to examine whether these dose reductions should be actively compensated and to estimate the magnitude of additional irradiations needed for dose compensation. Methods and Materials Quantitative edema resolution characteristics observed by Waterman et. el. were used to examine the physical and radiobiological effects of prostate edema in pre-planned 131Cs implants. The need for dose compensation was assessed based on the dose-responses observed in 125I and 103Pd prostate implants. Biologically effective dose calculated with full consideration of edema evolution was used to estimate the additional irradiations needed for dose compensation. Results Edema-induced dose reduction in pre-planned 131Cs implants could easily exceed 10% prescription dose for implants with moderate or large edemas. These dose reductions could lead to more than 10% reduction in biochemical recurrence-free survival for individual patients if the effect of edema was ignored. For a prescribed dose of 120 Gy, the number of 2-Gy external-beam fractions needed to compensate a 5%, 10%, 15%, 20%, or 25% edema-induced dose reduction could be 1, 4, 6, 7, or 9, respectively, for prostate cancers with a median potential doubling time of 42 days. The required additional irradiation increases for tumors that are fast growing and/or are less efficient in sub-lethal damage repair. Conclusions Compensation of edema-induced dose reductions in pre-planned 131Cs prostate brachytherapy should be actively considered for those implants with moderate or large edemas. PMID:17980500

  10. Directions of the US Geological Survey Landslide Hazards Reduction Program

    USGS Publications Warehouse

    Wieczorek, G.F.

    1993-01-01

    The US Geological Survey (USGS) Landslide Hazards Reduction Program includes studies of landslide process and prediction, landslide susceptibility and risk mapping, landslide recurrence and slope evolution, and research application and technology transfer. Studies of landslide processes have been recently conducted in Virginia, Utah, California, Alaska, and Hawaii, Landslide susceptibility maps provide a very important tool for landslide hazard reduction. The effects of engineering-geologic characteristics of rocks, seismic activity, short and long-term climatic change on landslide recurrence are under study. Detailed measurement of movement and deformation has begun on some active landslides. -from Author

  11. Professionals' attitudes after a seclusion reduction program: anything changed?

    PubMed

    Mann-Poll, P S; Smit, A; van Doeselaar, M; Hutschemaekers, G J M

    2013-03-01

    Changing professionals' attitudes toward seclusion is seen as an important condition to reduce its use. The purpose of this study was to determine whether professionals from a mental health institute in the Netherlands changed in their attitudes toward seclusion after implementation of a multifaceted seclusion reduction program. Professionals working on four acute admission wards filled in the Professional Attitudes Toward Seclusion Questionnaire (PATS-Q) before and after a seclusion reduction program. Changes were analyzed by comparing mean scores on the PATS-Q. After the program, professionals scored significantly higher on 'ethics' and 'more care'. As expected, no change occurred on 'reasons' for the use of seclusion. In addition, no significant changes were found on 'confidence', 'better care' and 'other care'. Significant changes in professional attitudes concerning the ethics of using seclusion and involving issues of more care were observed after a seclusion reduction program. Mental health professionals moved in the direction of 'transformers', indicating an increased criticism of the practice of seclusion and increased willingness to change their own use of seclusion. PMID:22610382

  12. Marketing cardiovascular disease risk reduction programs at the workplace. The Pawtucket Heart Health Program experience.

    PubMed

    Linnan, L A; Harden, E A; Bucknam, L; Carleton, R A

    1990-09-01

    The workplace offers a unique setting in which to offer CVD risk reduction programs. Marketing these programs involves at least two distinct processes. First, a corporation must agree to accept and support workplace health programming. Second, workplace programs must be effectively marketed to eligible employees, dependents, and retirees. After identifying critical barriers to the effective marketing of workplace programs, a stepwise approach used by the Pawtucket Heart Health Program to successfully overcome these obstacles is used. Using real world examples and practical tips, a discussion of implications for marketing future programs to the corporate and employee audience is shared. PMID:2397012

  13. Occupational dose reduction at Department of Energy contractor facilities: Bibliography of selected readings in radiation protection and ALARA; Volume 5

    SciTech Connect

    Dionne, B.J.; Sullivan, S.G.; Baum, J.W.

    1994-01-01

    Promoting the exchange of information related to implementation of the As Low as Reasonably Achievable (ALARA) philosophy is a continuing objective for the Department of Energy (DOE). This report was prepared by the Brookhaven National Laboratory (BNL) ALARA Center for the DOE Office of Health. It contains the fifth in a series of bibliographies on dose reduction at DOE facilities. The BNL ALARA Center was originally established in 1983 under the sponsorship of the Nuclear Regulatory Commission to monitor dose-reduction research and ALARA activities at nuclear power plants. This effort was expanded in 1988 by the DOE`s Office of Environment, Safety and Health, to include DOE nuclear facilities. This bibliography contains abstracts relating to various aspects of ALARA program implementation and dose-reduction activities, with a specific focus on DOE facilities. Abstracts included in this bibliography were selected from proceedings of technical meetings, journals, research reports, searches of the DOE Energy, Science and Technology Database (in general, the citation and abstract information is presented as obtained from this database), and reprints of published articles provided by the authors. Facility types and activities covered in the scope of this report include: radioactive waste, uranium enrichment, fuel fabrication, spent fuel storage and reprocessing, facility decommissioning, hot laboratories, tritium production, research, test and production reactors, weapons fabrication and testing, fusion, uranium and plutonium processing, radiography, and accelerators. Information on improved shielding design, decontamination, containments, robotics, source prevention and control, job planning, improved operational and design techniques, as well as on other topics, has been included. In addition, DOE/EH reports not included in previous volumes of the bibliography are in this volume (abstracts 611 to 684). This volume (Volume 5 of the series) contains 217 abstracts.

  14. RECOZ data reduction and analysis: Programs and procedures

    NASA Technical Reports Server (NTRS)

    Reed, E. I.

    1984-01-01

    The RECOZ data reduction programs transform data from the RECOZ photometer to ozone number density and overburden as a function of altitude. Required auxiliary data are the altitude profile versus time and for appropriate corrections to the ozone cross sections and scattering effects, air pressure and temperature profiles. Air temperature and density profiles may also be used to transform the ozone density versus geometric altitude to other units, such as to ozone partial pressure or mixing ratio versus pressure altitude. There are seven programs used to accomplish this: RADAR, LISTRAD, RAW OZONE, EDIT OZONE, MERGE, SMOOTH, and PROFILE.

  15. Results of the pollution reduction technology program for turboprop engines

    NASA Technical Reports Server (NTRS)

    Mularz, E. J.

    1976-01-01

    A program was performed to evolve and demonstrate advanced combustor technology aimed at achieving the 1979 EPA standards for turboprop engines (Class P2). The engine selected for this program was the 501-D22A turboprop. Three combustor concepts were designed and tested in a combustor rig at the exact combustor operating conditions of the 50-D22A engine over the EPA landing-takeoff cycle. Each combustor concept exhibited pollutant emissions well below the EPA standards, achieving substantial reductions in unburned hydrocarbons, carbon monoxide, and smoke emissions compared with emissions from the production combustor of this engine. Oxides of nitrogen emissions remained well below the EPA standards, also.

  16. Performance evaluation of iterative reconstruction algorithms for achieving CT radiation dose reduction - a phantom study.

    PubMed

    Dodge, Cristina T; Tamm, Eric P; Cody, Dianna D; Liu, Xinming; Jensen, Corey T; Wei, Wei; Kundra, Vikas; Rong, John

    2016-01-01

    The purpose of this study was to characterize image quality and dose performance with GE CT iterative reconstruction techniques, adaptive statistical iterative recon-struction (ASiR), and model-based iterative reconstruction (MBIR), over a range of typical to low-dose intervals using the Catphan 600 and the anthropomorphic Kyoto Kagaku abdomen phantoms. The scope of the project was to quantitatively describe the advantages and limitations of these approaches. The Catphan 600 phantom, supplemented with a fat-equivalent oval ring, was scanned using a GE Discovery HD750 scanner at 120 kVp, 0.8 s rotation time, and pitch factors of 0.516, 0.984, and 1.375. The mA was selected for each pitch factor to achieve CTDIvol values of 24, 18, 12, 6, 3, 2, and 1 mGy. Images were reconstructed at 2.5 mm thickness with filtered back-projection (FBP); 20%, 40%, and 70% ASiR; and MBIR. The potential for dose reduction and low-contrast detectability were evaluated from noise and contrast-to-noise ratio (CNR) measurements in the CTP 404 module of the Catphan. Hounsfield units (HUs) of several materials were evaluated from the cylinder inserts in the CTP 404 module, and the modulation transfer function (MTF) was calculated from the air insert. The results were con-firmed in the anthropomorphic Kyoto Kagaku abdomen phantom at 6, 3, 2, and 1mGy. MBIR reduced noise levels five-fold and increased CNR by a factor of five compared to FBP below 6mGy CTDIvol, resulting in a substantial improvement in image quality. Compared to ASiR and FBP, HU in images reconstructed with MBIR were consistently lower, and this discrepancy was reversed by higher pitch factors in some materials. MBIR improved the conspicuity of the high-contrast spatial resolution bar pattern, and MTF quantification confirmed the superior spatial resolution performance of MBIR versus FBP and ASiR at higher dose levels. While ASiR and FBP were relatively insensitive to changes in dose and pitch, the spatial resolution for MBIR

  17. Evaluation of the stepwise collimation method for the reduction of the patient dose in full spine radiography

    NASA Astrophysics Data System (ADS)

    Lee, Boram; Lee, Sunyoung; Yang, Injeong; Yoon, Myeonggeun

    2014-05-01

    The purpose of this study is to evaluate the dose reduction when using the stepwise collimation method for scoliosis patients undergoing full spine radiography. A Monte Carlo simulation was carried out to acquire dose vs. volume data for organs at risk (OAR) in the human body. While the effective doses in full spine radiography were reduced by 8, 15, 27 and 44% by using four different sizes of the collimation, the doses to the skin were reduced by 31, 44, 55 and 66%, indicating that the reduction of the dose to the skin is higher than that to organs inside the body. Although the reduction rates were low for the gonad, being 9, 14, 18 and 23%, there was more than a 30% reduction in the dose to the heart, suggesting that the dose reduction depends significantly on the location of the OARs in the human body. The reduction rate of the secondary cancer risk based on the excess absolute risk (EAR) varied from 0.6 to 3.4 per 10,000 persons, depending on the size of the collimation. Our results suggest that the stepwise collimation method in full spine radiography can effectively reduce the patient dose and the radiation-induced secondary cancer risk.

  18. Radiation dose reduction in digital radiography using wavelet-based image processing methods

    NASA Astrophysics Data System (ADS)

    Watanabe, Haruyuki; Tsai, Du-Yih; Lee, Yongbum; Matsuyama, Eri; Kojima, Katsuyuki

    2011-03-01

    In this paper, we investigate the effect of the use of wavelet transform for image processing on radiation dose reduction in computed radiography (CR), by measuring various physical characteristics of the wavelet-transformed images. Moreover, we propose a wavelet-based method for offering a possibility to reduce radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates the advantages of a previously proposed technique, i.e., sigmoid-type transfer curve for wavelet coefficient weighting adjustment technique, as well as a wavelet soft-thresholding technique. The former can improve contrast and spatial resolution of CR images, the latter is able to improve the performance of image noise. In the investigation of physical characteristics, modulation transfer function, noise power spectrum, and contrast-to-noise ratio of CR images processed by the proposed method and other different methods were measured and compared. Furthermore, visual evaluation was performed using Scheffe's pair comparison method. Experimental results showed that the proposed method could improve overall image quality as compared to other methods. Our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved in hip joint radiography by using the proposed method.

  19. Effects of dose reduction on the detectability of standardized radiolucent lesions in digital panoramic radiography.

    PubMed

    Dula, K; Sanderink, G; van der Stelt, P F; Mini, R; Buser, D

    1998-08-01

    Dose reduction in digital panoramic radiography was studied. Intentional underexposure was performed with the Orthophos DS while six different human mandibles were radiographed. Exposure settings were 69 kV/15 mA (standard), 64 kV/16 mA, and 60 kV/16 mA. Standardized spherical defects, each either 1 or 1.25 mm in diameter, were simulated in 288 of 432 images, and seven observers decided whether defects were present or not. Areas under the receiver operating characteristics curves were calculated. They showed no significant differences in the detectability of the 1-mm defect at 69, 64, or 60 kV. For the 1.25-mm defect, no difference was found between the 69 and 60 kV images, but a statistically significant different detectability was found for 64 kV images in comparison with both 69 and 60 kV images. A dose reduction of up to 43% was ascertained with a Pedo-RT-Humanoid phantom when panoramic radiography was performed at 60 kV/16 mA. The conclusion is that with the Orthophos DS, it seems possible to reduce the dose rate of x-rays without loss of diagnostic quality in the case of radiolucent changes. PMID:9720100

  20. Industrial Waste Reduction Program annual report, FY 1993

    SciTech Connect

    Not Available

    1994-01-01

    The Department of Energy`s Industrial Waste Reduction Program (IWRP) sponsors the development, demonstration, and deployment of technologies that offer a significant opportunity to reduce waste generation, improve productivity, and enhance environmental performance in US industry. The program emphasizes technology-driven solutions that are economically beneficial and environmentally sound. Its goal is to improve the energy efficiency and competitiveness of private industry by cost-effectively reducing waste. Industry, universities, national laboratories and other government agencies are working cooperatively to meet this goal. The IWRP emphasizes the timely commercialization of new technologies that can produce measurable energy, environmental, and economic benefits. All projects are substantially cost-shared with private companies to foster the commercialization process. The program is proud to claim four successfully commercialized technologies that have begun generating benefits. The current IWRP portfolio boasts 32 projects in progress. Funding for the IWRP has grown from $1.7 million in 1990 to $13 million in 1994. New companies join the program each year, reaping the benefits of working cooperatively with government. New technologies are expected to reach commercial success in fiscal year (FY) 1994, further increasing the benefits already accrued. Future Annual Reports will also include projects from the Waste Utilization and Conversion Program. Descriptions of the program`s 32 active projects are organized in this report according these elements. Each project description provides a brief background and the major accomplishments during FY 1993.

  1. Dose reduction of cone beam CT scanning for the entire oral and maxillofacial regions with thyroid collars

    PubMed Central

    Qu, XM; Li, G; Sanderink, GCH; Zhang, ZY; Ma, XC

    2012-01-01

    Objective The aim of this study was to evaluate the influence of thyroid collars on radiation dose during cone beam CT (CBCT) scanning. Methods Average tissue-absorbed dose for a NewTom 9000 CBCT scanner (Quantitative Radiology, Verona, Italy) was measured using thermoluminescent dosemeter chips in a phantom. The scans were carried out with and without thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection 2007 recommendations. Results The effective organ doses for the thyroid gland and oesophagus were 31.0 µSv and 2.4 µSv, respectively, during CBCT scanning without a collar around the neck. When the thyroid collars were used loosely around the neck, no effective organ dose reduction was observed. When one thyroid collar was used tightly on the front of the neck, the effective organ dose for the thyroid gland and oesophagus were reduced to 15.9 µSv (48.7% reduction) and 1.4 µSv (41.7% reduction), respectively. Similar organ dose reduction (46.5% and 41.7%) was achieved when CBCT scanning was performed with two collars tightly on the front and back of the neck. However, the differences to the total effective dose were not significant among the scans with and without collars around the neck (p = 0.775). Conclusions Thyroid collars can effectively reduce the radiation dose to the thyroid and oesophagus if used appropriately. PMID:22707330

  2. Experimental and clinical studies on dose reduction effects of spacers in interstitial brachytherapy for carcinoma of the mobile tongue.

    PubMed

    Fujita, M; Tamamoto, M; Hirokawa, Y; Kashiwado, K; Akagi, Y; Kashimoto, K; Wada, T

    1993-12-01

    The difference of radiation dose reduction effect with spacers of different materials, a heat-curing denture base resin and a silicon impression material, was examined experimentally and clinically. Radium needles and iridium hairpins were used as radioactive sources. In both studies, it was revealed that a dose reduction effect of silicon impression material was greater than that of denture base resin. Silicon impression material was thought to be a better material for spacers because of its larger radiation dose reduction effect and the time saving to produce the spacer. PMID:8284088

  3. Dose reduction for cardiac CT using a registration-based approach

    SciTech Connect

    Wierzbicki, Marcin; Guiraudon, Gerard M.; Jones, Douglas L.; Peters, Terry

    2007-06-15

    Two reasons for the recent rise in radiation exposure from CT are increases in its clinical applicability and the desire to maintain high SNR while acquiring smaller voxels. To address this emerging dose problem, several strategies for reducing patient exposure have already been proposed. One method employed in cardiac imaging is ECG-driven modulation of the tube current between 100% at one time point in the cardiac cycle and a reduced fraction at the remaining phases. In this paper, we describe how images obtained during such acquisition can be used to reconstruct 4D data of consistent high quality throughout the cardiac cycle. In our approach, we assume that the mid-diastole (MD) phase is imaged with full dose. The MD image is then independently registered to lower dose images (lower SNR) at other frames, resulting in a set of transformations. Finally, the transformations are used to warp the MD frame through the cardiac cycle to generate the full 4D image. In addition, the transformations may be interpolated to increase the temporal sampling or to generate images at arbitrary time points. Our approach was validated using various data obtained with simulated and scanner-implemented dose modulation. We determined that as little as 10% of the total dose was required to reproduce full quality images with a 1 mm spatial error and an error in intensity values on the order of the image noise. Thus, our technique offers considerable dose reductions compared to standard imaging protocols, with minimal effects on the quality of the final data.

  4. CT-guided brachytherapy of prostate cancer: reduction of effective dose from X-ray examination

    NASA Astrophysics Data System (ADS)

    Sanin, Dmitriy B.; Biryukov, Vitaliy A.; Rusetskiy, Sergey S.; Sviridov, Pavel V.; Volodina, Tatiana V.

    2014-03-01

    Computed tomography (CT) is one of the most effective and informative diagnostic method. Though the number of CT scans among all radiographic procedures in the USA and European countries is 11% and 4% respectively, CT makes the highest contribution to the collective effective dose from all radiographic procedures, it is 67% in the USA and 40% in European countries [1-5]. Therefore it is necessary to understand the significance of dose value from CT imaging to a patient . Though CT dose from multiple scans and potential risk is of great concern in pediatric patients, this applies to adults as well. In this connection it is very important to develop optimal approaches to dose reduction and optimization of CT examination. International Commission on Radiological Protection (ICRP) in its publications recommends radiologists to be aware that often CT image quality is higher than it is necessary for diagnostic confidence[6], and there is a potential to reduce the dose which patient gets from CT examination [7]. In recent years many procedures, such as minimally invasive surgery, biopsy, brachytherapy and different types of ablation are carried out under guidance of computed tomography [6;7], and during a procedures multiple CT scans focusing on a specific anatomic region are performed. At the Clinics of MRRC different types of treatment for patients with prostate cancer are used, incuding conformal CT-guided brachytherapy, implantation of microsources of I into the gland under guidance of spiral CT [8]. So, the purpose of the study is to choose optimal method to reduce radiation dose from CT during CT-guided prostate brachytherapy and to obtain the image of desired quality.

  5. Dose reduction for cardiac CT using a registration-based approach.

    PubMed

    Wierzbicki, Marcin; Guiraudon, Gérard M; Jones, Douglas L; Peters, Terry

    2007-06-01

    Two reasons for the recent rise in radiation exposure from CT are increases in its clinical applicability and the desire to maintain high SNR while acquiring smaller voxels. To address this emerging dose problem, several strategies for reducing patient exposure have already been proposed. One method employed in cardiac imaging is ECG-driven modulation of the tube current between 100% at one time point in the cardiac cycle and a reduced fraction at the remaining phases. In this paper, we describe how images obtained during such acquisition can be used to reconstruct 4D data of consistent high quality throughout the cardiac cycle. In our approach, we assume that the middiastole (MD) phase is imaged with full dose. The MD image is then independently registered to lower dose images (lower SNR) at other frames, resulting in a set of transformations. Finally, the transformations are used to warp the MD frame through the cardiac cycle to generate the full 4D image. In addition, the transformations may be interpolated to increase the temporal sampling or to generate images at arbitrary time points. Our approach was validated using various data obtained with simulated and scanner-implemented dose modulation. We determined that as little as 10% of the total dose was required to reproduce full quality images with a 1 mm spatial error and an error in intensity values on the order of the image noise. Thus, our technique offers considerable dose reductions compared to standard imaging protocols, with minimal effects on the quality of the final data. PMID:17654889

  6. An adaptive gating approach for x-ray dose reduction during cardiac interventional procedures

    SciTech Connect

    Abdel-Malek, A.; Yassa, F.; Bloomer, J. )

    1994-03-01

    The increasing number of cardiac interventional procedures has resulted in a tremendous increase in the absorbed x-ray dose by radiologists as well as patients. A new method is presented for x-ray dose reduction which utilizes adaptive tube pulse-rate scheduling in pulsed fluoroscopic systems. In the proposed system, pulse-rate scheduling depends on the heart muscle activity phase determined through continuous guided segmentation of the patient's electrocardiogram (ECG). Displaying images generated at the proposed adaptive nonuniform rate is visually unacceptable; therefore, a frame-filling approach is devised to ensure a 30 frame/sec display rate. The authors adopted two approaches for the frame-filling portion of the system depending on the imaging mode used in the procedure. During cine-mode imaging (high x-ray dose), collected image frame-to-frame pixel motion is estimated using a pel-recursive algorithm followed by motion-based pixel interpolation to estimate the frames necessary to increase the rate to 30 frames/sec. The other frame-filling approach is adopted during fluoro-mode imaging (low x-ray dose), characterized by low signal-to-noise ratio images. This approach consists of simply holding the last collected frame for as many frames as necessary to maintain the real-time display rate.

  7. Dose reduction using non lineal diffusion and smoothing filters in computed radiography

    NASA Astrophysics Data System (ADS)

    Sánchez, M. G.; Juste, B.; Vidal, V.; Verdú, G.; Mayo, P.; Rodenas, F.

    2014-02-01

    The use of Computed Radiography (CR) into clinical practice has been followed by a high increase in the number of examinations performed and overdose cases in patients, especially children in pediatric applications. Computed radiographic images are corrupted by noise because either data acquisition or data transmission. The level of this inherent noise is related with the X-ray dose exposure: lower radiation exposure involves higher noise level. The main aim of this work is to reduce the noise present in a low radiation dose CR image in order to the get a CR image of the same quality as a higher radiation exposure image. In this work, we use a non lineal diffusion filtering method to reduce the noise level in a CR, this means that we are able to reduce the exposure, milliampere-second (mAs), and the dose absorbed by the patients. In order to get an optimal result, the diffusive filter is complemented with a smoothing filter with edge detection in order to preserve edges. Therefore, the proposed method consists in obtaining a good quality CR image for diagnostic purposes by selection of lower X-ray exposure jointly with a reduction of the noise. We conclude that a good solution to minimize the dose to patients, especially children in pediatric applications, in X-ray computed radiography consists in decreasing the mAs of the X-ray exposure and then processing the image with the proposed method.

  8. Lipowitz metal shielding thickness for dose reduction of 6-20 MeV electrons.

    PubMed

    Purdy, J A; Choi, M C; Feldman, A

    1980-01-01

    The relative dose reduction by Lipowitz metal of 6 to 20 MeV electrons from a Varian Associates Clinac-20 linear accelerator has been measured using a parallel plate thin wall ionization chamber. Metal thickness required for a 5% attenuation level for a 10 X 10 cm2 field are as follows: 6 MeV-2.3 mm, 9 MeV-4.4 mm, 12 MeV-8.5 mm, 16 MeV--18.0 mm, 20 MeV-25.0 mm. PMID:7393151

  9. Acceptance test procedure for K basins dose reduction project clean and coat equipment

    SciTech Connect

    Creed, R.F.

    1996-03-11

    This document is the Acceptance Test Procedure (ATP) for the clean and coat equipment designed by Oceaneering Hanford, Inc. under purchase order MDK-XVC-406988 for use in the 105 K East Basin. The ATP provides the guidelines and criteria to test the equipment`s ability to clean and coat the concrete perimeter, divider walls, and dummy elevator pit above the existing water level. This equipment was designed and built in support of the Spent Nuclear Fuel, Dose Reduction Project. The ATP will be performed at the 305 test facility in the 300 Area at Hanford. The test results will be documented in WHC-SD-SNF-ATR-020.

  10. Short arc reduction of radar altimetry computer program

    NASA Technical Reports Server (NTRS)

    Hadgigeorge, G.; Trotter, J.

    1978-01-01

    The Air Force Geophysics Laboratory computer program SARRA (Short Arc Reduction of Radar Altimetry) has been used for geoid determination with altimetric observations from the GEOS-3 satellite. An important feature of SARRA is the simultaneous recovery of the orbit parameters and the surface coefficients as defined by covariance function weights. Orbits good to approximately 20 meters are adequate for precise geoid determinations by virtue of the orbital adjustment in the reductions. Altimetric data over a portion of the North Atlantic Ocean have been processed to derive the regional geoid and gravity field. Analyses of altimeter residuals resulting from the short arc adjustment show that the residuals can be used to define the neglected higher order geoidal undulations with high fidelity and continuity.

  11. Space program payload costs and their possible reduction

    NASA Technical Reports Server (NTRS)

    Vanvleck, E. M.; Deerwester, J. M.; Norman, S. M.; Alton, L. R.

    1973-01-01

    The possible ways by which NASA payload costs might be reduced in the future were studied. The major historical reasons for payload costs being as they were, and if there are technologies (hard and soft), or criteria for technology advances, that could significantly reduce total costs of payloads were examined. Payload costs are placed in historical context. Some historical cost breakdowns for unmanned NASA payloads are presented to suggest where future cost reductions could be most significant. Space programs of NOAA, DoD and COMSAT are then examined to ascertain if payload reductions have been brought about by the operational (as opposed to developmental) nature of such programs, economies of scale, the ability to rely on previously developed technology, or by differing management structures and attitudes. The potential impact was investigated of NASA aircraft-type management on spacecraft program costs, and some examples relating previous costs associated with aircraft costs on the one hand and manned and unmanned costs on the other are included.

  12. JWST Pathfinder Telescope Risk Reduction Cryo Test Program

    NASA Technical Reports Server (NTRS)

    Matthews, Gary W.; Scorse, Thomas R.; Spina, John A.; Noel, Darin M.; Havey, Keith A., Jr.; Huguet, Jesse A.; Whitman, Tony L.; Wells, Conrad; Walker, Chanda B.; Lunt, Sharon; Hadaway, James B.; Keski-Kuha, Ritva; Feinberg, Lee D.; Voyton, Mark F.; Lander, Juli A.; Marsh, James M.

    2015-01-01

    In 2014, the Optical Ground Support Equipment was integrated into the large cryo vacuum chamber at Johnson Space Center (JSC) and an initial Chamber Commissioning Test was completed. This insured that the support equipment was ready for the three Pathfinder telescope cryo tests. The Pathfinder telescope which consists of two primary mirror segment assemblies and the secondary mirror was delivered to JSC in February 2015 in support of this critical risk reduction test program prior to the flight hardware. This paper will detail the Chamber Commissioning and first optical test of the JWST Pathfinder telescope.

  13. JWST pathfinder telescope risk reduction cryo test program

    NASA Astrophysics Data System (ADS)

    Matthews, Gary W.; Scorse, Thomas R.; Spina, John A.; Noël, Darin M.; Havey, Keith A.; Huguet, Jesse A.; Whitman, Tony L.; Wells, Conrad; Walker, Chanda B.; Lunt, Sharon; Hadaway, James B.; Keski-Kuha, Ritva; Feinberg, Lee D.; Voyton, Mark F.; Lander, Juli A.; Marsh, James M.

    2015-08-01

    In 2014, the Optical Ground Support Equipment was integrated into the large cryo vacuum chamber at Johnson Space Center (JSC) and an initial Chamber Commissioning Test was completed. This insured that the support equipment was ready for the three Pathfinder telescope cryo tests. The Pathfinder telescope which consists of two primary mirror segment assemblies and the secondary mirror was delivered to JSC in February 2015 in support of this critical risk reduction test program prior to the flight hardware. This paper will detail the Chamber Commissioning and first optical test of the JWST Pathfinder telescope.

  14. Sludge reduction at low ozone doses: predictive effects and full-scale study.

    PubMed

    Romero, P; Coello, M D; Aragón, C A; Eusebi, A L

    2015-01-01

    The activated sludge process is the most widely used wastewater treatment. The main drawback of this technology is the excess sludge production (ESP). The ozonation of sludge of the recirculation line is used to reduce the ESP. In this study, ozonation was applied on a fraction of sludge of the recirculation line in a full-scale plant (50,000 population equivalent) at a lower-specific ozone dose (SOD) compared to previous studies. The results of batch tests to predict the main effect of the technology on the biomass activities are reported. Specifically, tests at 0.7-5 g O₃/kg MLVSS (mixed liquor volatile suspended solids) doses were made to evaluate the changes of the nitrification and denitrification rates, the population of phosphate-accumulating organisms and the gravitational properties. A certain reduction of the impact of ozonation on the kinetic parameters of sludge for values of SOD over 2 g O₃/kg MLVSS was found. The present study highlights also the use of the ratio of ozonated biomass to total biomass as an important operative parameter for ozonation in full-scale plants. Reduction in ESP in the wastewater treatment plant was equal to 10% as dry solids applying a SOD from 1.03 to 1.63 g O₃/kg MLVSS. An analysis of the economic cost of the technique is also reported. PMID:25633941

  15. Spectroscopic reduction and analysis programs at the DAO

    NASA Astrophysics Data System (ADS)

    Hill, G.

    In this paper I outline the \\fortran programs available at the DAO to process and synthesize spectra, loosely described under the generic name REDUCE. The viewpoint is that of a research scientist who develops and uses his own software, and who writes collaboratively for colleagues. Much of the software has been available on the DAO's VAX machines since the early 80s and is slowly being converted to SUNs, although recent developments involve the use of DEC Alphas. The rationale behind the various reduction and analytic software is outlined, as well as the way the programs are controlled, e.g., menu, questions and answers, keywords and values, or the cursor. Some particularly useful tools are mentioned, such as, interpolation, optimization, and error analysis.

  16. Results of the pollution reduction technology program for turboprop engines

    NASA Technical Reports Server (NTRS)

    Mularz, E. J.

    1976-01-01

    A program was performed to evolve and demonstrate advanced combustor technology aimed at achieving the 1979 EPA standards for turboprop engines (Class P2). The engine selected for this program was the 501-D22A turboprop manufactured by Detroit Diesel Allison Division of General Motors Corporation. Three combustor concepts were designed and tested in a combustor rig at the exact combustor operating conditions of the 501-D22A engine over the EPA landing-takeoff cycle. Each combustor concept exhibited pollutant emissions well below the EPA standards, achieving substantial reductions in unburned hydrocarbons, carbon monoxide, and smoke emissions compared with emissions from the production combustor of this engine. Oxides of nitrogen emissions remained well below the EPA standards, also.

  17. Radiation Dose Reduction in Transmission CT Using a Novel Iterative Fourier-Based Reconstruction Technique

    NASA Astrophysics Data System (ADS)

    Fahimian, Benjamin Pooya

    Tomographic imaging has had a radical impact on diverse fields ranging from the study of the small in microscopy, to the study of the large in astronomy, but perhaps most significantly, it has unequivocally revolutionized the practice of medicine. Although the applications of tomography are wide and diverse, the central problems associated with its mathematical and experimental implementation are similar. Most notably, the problem of image reconstruction from missing and noisy projection data and the problem of radiation dose imparted to biological specimens and patients are persistent and prominent problems in tomographic applications. Since by virtue of its nature, tomographic reconstruction is a mathematical problem, the development of more accurate and sophisticated reconstruction algorithms capable of solving for missing projection data and or producing accurate lower noise reconstructions, may hold promise in alleviating such problems. In this work, a method of tomographic acquisition and exact iterative Fourier-based reconstruction is developed, which in conjunction with physical constraints, advanced regularization constraints, and an oversampling method, aims to solve for the missing projection data and arrive at a less noisy solution in a manner that is concurrently and strictly consistent with the experimental data. Specifically, the proposed technique, termed Equally-Sloped Tomography (EST), is experimentally implemented and evaluated on four important transmission tomographic imaging modalities: transmission electron microtomography, synchrotron x-ray phase contrast tomography, synchrotron x-ray absorption tomography, and kilovoltage x-ray medical CT. In each modality, using a series of image quality phantoms studies, the performance of technique is quantitatively assessed and compared to existing methods. The potential for dose reduction is investigated by determining the factor by which the number of projections or the source flux can be reduced

  18. Programmed emulsions for sodium reduction in emulsion based foods.

    PubMed

    Chiu, Natalie; Hewson, Louise; Fisk, Ian; Wolf, Bettina

    2015-05-01

    In this research a microstructure approach to reduce sodium levels in emulsion based foods is presented. If successful, this strategy will enable reduction of sodium without affecting consumer satisfaction with regard to salty taste. The microstructure approach comprised of entrapment of sodium in the internal aqueous phase of water-in-oil-in-water emulsions. These were designed to destabilise during oral processing when in contact with the salivary enzyme amylase in combination with the mechanical manipulation of the emulsion between the tongue and palate. Oral destabilisation was achieved through breakdown of the emulsion that was stabilised with a commercially modified octenyl succinic anhydride (OSA)-starch. Microstructure breakdown and salt release was evaluated utilising in vitro, in vivo and sensory methods. For control emulsions, stabilised with orally inert proteins, no loss of structure and no release of sodium from the internal aqueous phase was found. The OSA-starch microstructure breakdown took the initial form of oil droplet coalescence. It is hypothesised that during this coalescence process sodium from the internalised aqueous phase is partially released and is therefore available for perception. Indeed, programmed emulsions showed an enhancement in saltiness perception; a 23.7% reduction in sodium could be achieved without compromise in salty taste (p < 0.05; 120 consumers). This study shows a promising new approach for sodium reduction in liquid and semi-liquid emulsion based foods. PMID:25865459

  19. Development of a Pediatric Fall Risk And Injury Reduction Program.

    PubMed

    Kramlich, Debra L; Dende, Denise

    2016-01-01

    Fall prevention programs that include reliable, valid, and clinically tested screening tools have demonstrated more positive effects for adult and geriatric populations than those not including such assessment. In contrast, because falling is a natural part of growth and development for pediatric patients, progression toward effective prevention programs for this population has proven to be a challenge; a significant impediment is the lack of definition regarding what constitutes a reportable fall. This project explored pediatric health care providers' perceptions of patient falls in order to define a reportable pediatric fall and inform development of a prevention program. A concept analysis of defining attributes, antecedents, and consequences of pediatric falls from literature formed the basis for a set of questions; a convenience sample of 28 pediatric health care providers in an acute care hospital in New England participated in six moderated focus groups. Constant comparison method was used to code the qualitative data and develop themes. Participants unanimously agreed on several points; as expected, their years of experience in pediatric practice provided valuable insight. Three major themes emerged: patient characteristics, caregiver characteristics, and environmental characteristics. Based on factors identified by staff, a screening tool was adopted and integrated into the electronic medical record. Staff were actively engaged in developing definitions, selecting tools, and identifying next steps toward a comprehensive fall reduction program for their patients. As a result, they have embraced changes and advocated successfully for endorsement by the organization. PMID:27254976

  20. PWR Facility Dose Modeling Using MCNP5 and the CADIS/ADVANTG Variance-Reduction Methodology

    SciTech Connect

    Blakeman, Edward D; Peplow, Douglas E.; Wagner, John C; Murphy, Brian D; Mueller, Don

    2007-09-01

    The feasibility of modeling a pressurized-water-reactor (PWR) facility and calculating dose rates at all locations within the containment and adjoining structures using MCNP5 with mesh tallies is presented. Calculations of dose rates resulting from neutron and photon sources from the reactor (operating and shut down for various periods) and the spent fuel pool, as well as for the photon source from the primary coolant loop, were all of interest. Identification of the PWR facility, development of the MCNP-based model and automation of the run process, calculation of the various sources, and development of methods for visually examining mesh tally files and extracting dose rates were all a significant part of the project. Advanced variance reduction, which was required because of the size of the model and the large amount of shielding, was performed via the CADIS/ADVANTG approach. This methodology uses an automatically generated three-dimensional discrete ordinates model to calculate adjoint fluxes from which MCNP weight windows and source bias parameters are generated. Investigative calculations were performed using a simple block model and a simplified full-scale model of the PWR containment, in which the adjoint source was placed in various regions. In general, it was shown that placement of the adjoint source on the periphery of the model provided adequate results for regions reasonably close to the source (e.g., within the containment structure for the reactor source). A modification to the CADIS/ADVANTG methodology was also studied in which a global adjoint source is weighted by the reciprocal of the dose response calculated by an earlier forward discrete ordinates calculation. This method showed improved results over those using the standard CADIS/ADVANTG approach, and its further investigation is recommended for future efforts.

  1. Reduction in radiation dose with reconstruction technique in the brain perfusion CT

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Lee, H. K.; Song, H.; Ju, M. S.; Dong, K. R.; Chung, W. K.; Cho, M. S.; Cho, J. H.

    2011-12-01

    The principal objective of this study was to verify the utility of the reconstruction imaging technique in the brain perfusion computed tomography (PCT) scan by assessing reductions in the radiation dose and analyzing the generated images. The setting used for image acquisition had a detector coverage of 40 mm, a helical thickness of 0.625 mm, a helical shuttle mode scan type and a rotation time of 0.5 s as the image parameters used for the brain PCT scan. Additionally, a phantom experiment and an animal experiment were carried out. In the phantom and animal experiments, noise was measured in the scanning with the tube voltage fixed at 80 kVp (kilovolt peak) and the level of the adaptive statistical iterative reconstruction (ASIR) was changed from 0% to 100% at 10% intervals. The standard deviation of the CT coefficient was measured three times to calculate the mean value. In the phantom and animal experiments, the absorbed dose was measured 10 times under the same conditions as the ones for noise measurement before the mean value was calculated. In the animal experiment, pencil-type and CT-dedicated ionization chambers were inserted into the central portion of pig heads for measurement. In the phantom study, as the level of the ASIR changed from 0% to 100% under identical scanning conditions, the noise value and dose were proportionally reduced. In our animal experiment, the noise value was lowest when the ASIR level was 50%, unlike in the phantom study. The dose was reduced as in the phantom study.

  2. 2nd Generation RLV Risk Reduction Definition Program: Pratt & Whitney Propulsion Risk Reduction Requirements Program (TA-3 & TA-4)

    NASA Technical Reports Server (NTRS)

    Matlock, Steve

    2001-01-01

    This is the final report and addresses all of the work performed on this program. Specifically, it covers vehicle architecture background, definition of six baseline engine cycles, reliability baseline (space shuttle main engine QRAS), and component level reliability/performance/cost for the six baseline cycles, and selection of 3 cycles for further study. This report further addresses technology improvement selection and component level reliability/performance/cost for the three cycles selected for further study, as well as risk reduction plans, and recommendation for future studies.

  3. Radiation dose reduction in medical x-ray CT via Fourier-based iterative reconstruction

    SciTech Connect

    Fahimian, Benjamin P.; Zhao Yunzhe; Huang Zhifeng; Fung, Russell; Zhu Chun; Miao Jianwei; Mao Yu; Khatonabadi, Maryam; DeMarco, John J.; McNitt-Gray, Michael F.; Osher, Stanley J.

    2013-03-15

    Purpose: A Fourier-based iterative reconstruction technique, termed Equally Sloped Tomography (EST), is developed in conjunction with advanced mathematical regularization to investigate radiation dose reduction in x-ray CT. The method is experimentally implemented on fan-beam CT and evaluated as a function of imaging dose on a series of image quality phantoms and anonymous pediatric patient data sets. Numerical simulation experiments are also performed to explore the extension of EST to helical cone-beam geometry. Methods: EST is a Fourier based iterative algorithm, which iterates back and forth between real and Fourier space utilizing the algebraically exact pseudopolar fast Fourier transform (PPFFT). In each iteration, physical constraints and mathematical regularization are applied in real space, while the measured data are enforced in Fourier space. The algorithm is automatically terminated when a proposed termination criterion is met. Experimentally, fan-beam projections were acquired by the Siemens z-flying focal spot technology, and subsequently interleaved and rebinned to a pseudopolar grid. Image quality phantoms were scanned at systematically varied mAs settings, reconstructed by EST and conventional reconstruction methods such as filtered back projection (FBP), and quantified using metrics including resolution, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs). Pediatric data sets were reconstructed at their original acquisition settings and additionally simulated to lower dose settings for comparison and evaluation of the potential for radiation dose reduction. Numerical experiments were conducted to quantify EST and other iterative methods in terms of image quality and computation time. The extension of EST to helical cone-beam CT was implemented by using the advanced single-slice rebinning (ASSR) method. Results: Based on the phantom and pediatric patient fan-beam CT data, it is demonstrated that EST reconstructions with the lowest

  4. Assessment of patient dose reduction by bismuth shielding in CT using measurements, GEANT4 and MCNPX simulations.

    PubMed

    Mendes, M; Costa, F; Figueira, C; Madeira, P; Teles, P; Vaz, P

    2015-07-01

    This work reports on the use of two different Monte Carlo codes (GEANT4 and MCNPX) for assessing the dose reduction using bismuth shields in computer tomography (CT) procedures in order to protect radiosensitive organs such as eye lens, thyroid and breast. Measurements were performed using head and body PMMA phantoms and an ionisation chamber placed in five different positions of the phantom. Simulations were performed to estimate Computed Tomography Dose Index values using GEANT4 and MCNPX. The relative differences between measurements and simulations were <10 %. The dose reduction arising from the use of bismuth shielding ranges from 2 to 45 %, depending on the position of the bismuth shield. The percentage of dose reduction was more significant for the area covered by the bismuth shielding (36 % for eye lens, 39 % for thyroid and 45 % for breast shields). PMID:25813483

  5. Noise Reduction for Low-Dose Single-Slice Helical CT Sinograms

    PubMed Central

    Wang, Jing; Li, Tianfang; Lu, Hongbing; Liang, Zhengrong

    2006-01-01

    Helical computed tomography (HCT) has several advantages over conventional step-and-shoot CT for imaging a relatively large object, especially for dynamic studies. However, HCT may increase X-ray exposure significantly. This work aims to reduce the radiation by lowering X-ray tube current (mA) and filtering low-mA (or dose) sinogram noise of HCT. The noise reduction method is based on three observations on HCT: (1) the axial sampling of HCT projections is nearly continuous as detection system rotates; (2) the noise distribution in sinogram space is nearly a Gaussian after system calibration (including logarithmic transform); and (3) the relationship between the calibrated data mean and variance can be expressed as an exponential functional across the field-of-view. Based on the second and third observations, a penalized weighted least-squares (PWLS) solution is an optimal choice, where the weight is given by the mean-variance relationship. The first observation encourages the use of Karhunen-Loève (KL) transform along the axial direction because of the associated correlation. In the KL domain, the eigenvalue of each principal component and the derived data variance provide the signal-to-noise ratio (SNR) information, resulting in a SNR-adaptive noise reduction. The KL-PWLS noise-reduction method was implemented analytically for efficient restoration of large volume HCT sinograms. Simulation studies showed a noticeable improvement, in terms of image quality and defect detectability, of the proposed noise-reduction method over the Ordered-Subsets Expectation-Maximization reconstruction and the conventional low-pass noise filtering with optimal cutoff frequency and/or other filter parameters. PMID:16932806

  6. Radiation dose reduction in computed tomography (CT) using a new implementation of wavelet denoising in low tube current acquisitions

    NASA Astrophysics Data System (ADS)

    Tao, Yinghua; Brunner, Stephen; Tang, Jie; Speidel, Michael; Rowley, Howard; VanLysel, Michael; Chen, Guang-Hong

    2011-03-01

    Radiation dose reduction remains at the forefront of research in computed tomography. X-ray tube parameters such as tube current can be lowered to reduce dose; however, images become prohibitively noisy when the tube current is too low. Wavelet denoising is one of many noise reduction techniques. However, traditional wavelet techniques have the tendency to create an artificial noise texture, due to the nonuniform denoising across the image, which is undesirable from a diagnostic perspective. This work presents a new implementation of wavelet denoising that is able to achieve noise reduction, while still preserving spatial resolution. Further, the proposed method has the potential to improve those unnatural noise textures. The technique was tested on both phantom and animal datasets (Catphan phantom and timeresolved swine heart scan) acquired on a GE Discovery VCT scanner. A number of tube currents were used to investigate the potential for dose reduction.

  7. Dose reduction assessment in dynamic CT myocardial perfusion imaging in a porcine balloon-induced-ischemia model

    NASA Astrophysics Data System (ADS)

    Fahmi, Rachid; Eck, Brendan L.; Vembar, Mani; Bezerra, Hiram G.; Wilson, David L.

    2014-03-01

    We investigated the use of an advanced hybrid iterative reconstruction (IR) technique (iDose4, Philips Health- care) for low dose dynamic myocardial CT perfusion (CTP) imaging. A porcine model was created to mimic coronary stenosis through partial occlusion of the left anterior descending (LAD) artery with a balloon catheter. The severity of LAD occlusion was adjusted with FFR measurements. Dynamic CT images were acquired at end-systole (45% R-R) using a multi-detector CT (MDCT) scanner. Various corrections were applied to the acquired scans to reduce motion and imaging artifacts. Absolute myocardial blood flow (MBF) was computed with a deconvolution-based approach using singular value decomposition (SVD). We compared a high and a low dose radiation protocol corresponding to two different tube-voltage/tube-current combinations (80kV p/100mAs and 120kV p/150mAs). The corresponding radiation doses for these protocols are 7.8mSv and 34.3mSV , respectively. The images were reconstructed using conventional FBP and three noise-reduction strengths of the IR method, iDose. Flow contrast-to-noise ratio, CNRf, as obtained from MBF maps, was used to quantitatively evaluate the effect of reconstruction on contrast between normal and ischemic myocardial tissue. Preliminary results showed that the use of iDose to reconstruct low dose images provide better or comparable CNRf to that of high dose images reconstructed with FBP, suggesting significant dose savings. CNRf was improved with the three used levels of iDose compared to FBP for both protocols. When using the entire 4D dynamic sequence for MBF computation, a 77% dose reduction was achieved, while considering only half the scans (i.e., every other heart cycle) allowed even further dose reduction while maintaining relatively higher CNRf.

  8. Integrating COPD into Patient-Centered Hospital Readmissions Reduction Programs

    PubMed Central

    Krishnan, Jerry A.; Gussin, Hélène A.; Prieto-Centurion, Valentin; Sullivan, Jamie L.; Zaidi, Farhan; Thomashow, Byron M.

    2015-01-01

    About 1 in 5 patients hospitalized for exacerbations of chronic obstructive pulmonary disease (COPD) in the United States are readmitted within 30 days. The U.S. Centers for Medicare and Medicaid Services has recently expanded its Hospital Readmissions Reduction Program to financially penalize hospitals with higher than expected all-cause 30-day readmission rates following a hospitalization for COPD exacerbation. In October 2013, the COPD Foundation convened a multi-stakeholder National COPD Readmissions Summit to summarize our understanding of how to reduce hospital readmissions in patients hospitalized for COPD exacerbations. Over 225 individuals participated in the Summit, including patients, clinicians, health service researchers, policy makers and representatives of academic health care centers, industry, and payers. Summit participants recommend that programs to reduce hospital readmissions: 1) Include specific recommendations about how to promote COPD self-management skills training for patients and their caregivers; 2) Adequately address co-existing disorders common to COPD in care plans during and after hospitalizations; 3) Include an evaluation of adverse events when implementing strategies to reduce hospital readmissions; and 4) Develop a strategy (e.g., a learning collaboratory) to connect groups who are engaged in developing, testing, and implementing programs to reduce hospital readmissions for COPD and other conditions. PMID:25927076

  9. Dose Reduction Study in Vaginal Balloon Packing Filled With Contrast for HDR Brachytherapy Treatment;HDR; Uterine cervix cancer; Vaginal balloon packing; Contrast; Monte Carlo

    SciTech Connect

    Saini, Amarjit S.; Zhang, Geoffrey G.; Finkelstein, Steven E.; Biagioli, Matthew C.

    2011-07-15

    Purpose: Vaginal balloon packing is a means to displace organs at risk during high dose rate brachytherapy of the uterine cervix. We tested the hypothesis that contrast-filled vaginal balloon packing reduces radiation dose to organs at risk, such as the bladder and rectum, in comparison to water- or air-filled balloons. Methods and Materials: In a phantom study, semispherical vaginal packing balloons were filled with air, saline solution, and contrast agents. A high dose rate iridium-192 source was placed on the anterior surface of the balloon, and the diode detector was placed on the posterior surface. Dose ratios were taken with each material in the balloon. Monte Carlo (MC) simulations, by use of the MC computer program DOSXYZnrc, were performed to study dose reduction vs. balloon size and contrast material, including commercially available iodine- and gadolinium-based contrast agents. Results: Measured dose ratios on the phantom with the balloon radius of 3.4 cm were 0.922 {+-} 0.002 for contrast/saline solution and 0.808 {+-} 0.001 for contrast/air. The corresponding ratios by MC simulations were 0.895 {+-} 0.010 and 0.781 {+-} 0.010. The iodine concentration in the contrast was 23.3% by weight. The dose reduction of contrast-filled balloon ranges from 6% to 15% compared with water-filled balloon and 11% to 26% compared with air-filled balloon, with a balloon size range between 1.4 and 3.8 cm, and iodine concentration in contrast of 24.9%. The dose reduction was proportional to the contrast agent concentration. The gadolinium-based contrast agents showed less dose reduction because of much lower concentrations in their solutions. Conclusions: The dose to the posterior wall of the bladder and the anterior wall of the rectum can be reduced if the vaginal balloon is filled with contrast agent in comparison to vaginal balloons filled with saline solution or air.

  10. Modeling and testing of a non-standard scanning device with dose reduction potential

    NASA Astrophysics Data System (ADS)

    de las Heras, Hugo; Tischenko, Oleg; Panzer, Werner; Xu, Yuan; Hoeschen, Christoph

    2007-03-01

    A non-standard scanning device with dose-reduction potential was proposed at the SPIE Medical Imaging conference 2006. The new device obtains the Radon data after the X-ray beam is collimated through a special mask. This mask is combined with a new geometry that permits an efficient data collection, thus the device has the potential of reducing the dose by a factor of two. In this work, we report a prototype of the new device and experimental data acquisition using only the mask of the new scanning geometry. In order to obtain the optimal parameters for the scanning device, several factors have been considered, including detector elements and shielding shape, fan beam angle, speed of the source rotation and materials employed. The calibration of the detector elements needs especial attention, due to the dependence of the detector response on the energy of the X-rays. A simplfied version of the device was designed and mounted. Phantom data were acquired using this prototype and were used to test the performance of the new design. The results obtained are highly promising, even though the prototype developed does not make use yet of all the potential features proposed in the theory.

  11. Comp Plan: A computer program to generate dose and radiobiological metrics from dose-volume histogram files

    SciTech Connect

    Holloway, Lois Charlotte; Miller, Julie-Anne; Kumar, Shivani; Whelan, Brendan M.; Vinod, Shalini K.

    2012-10-01

    Treatment planning studies often require the calculation of a large number of dose and radiobiological metrics. To streamline these calculations, a computer program called Comp Plan was developed using MATLAB. Comp Plan calculates common metrics, including equivalent uniform dose, tumor control probability, and normal tissue complication probability from dose-volume histogram data. The dose and radiobiological metrics can be calculated for the original data or for an adjusted fraction size using the linear quadratic model. A homogeneous boost dose can be added to a given structure if desired. The final output is written to an Excel file in a format convenient for further statistical analysis. Comp Plan was verified by independent calculations. A lung treatment planning study comparing 45 plans for 7 structures using up to 6 metrics for each structure was successfully analyzed within approximately 5 minutes with Comp Plan. The code is freely available from the authors on request.

  12. A technique optimization protocol and the potential for dose reduction in digital mammography

    PubMed Central

    Ranger, Nicole T.; Lo, Joseph Y.; Samei, Ehsan

    2010-01-01

    Digital mammography requires revisiting techniques that have been optimized for prior screen∕film mammography systems. The objective of the study was to determine optimized radiographic technique for a digital mammography system and demonstrate the potential for dose reduction in comparison to the clinically established techniques based on screen- film. An objective figure of merit (FOM) was employed to evaluate a direct-conversion amorphous selenium (a-Se) FFDM system (Siemens Mammomat NovationDR, Siemens AG Medical Solutions, Erlangen, Germany) and was derived from the quotient of the squared signal-difference-to-noise ratio to mean glandular dose, for various combinations of technique factors and breast phantom configurations including kilovoltage settings (23–35 kVp), target∕filter combinations (Mo–Mo and W–Rh), breast-equivalent plastic in various thicknesses (2–8 cm) and densities (100% adipose, 50% adipose∕50% glandular, and 100% glandular), and simulated mass and calcification lesions. When using a W–Rh spectrum, the optimized FOM results for the simulated mass and calcification lesions showed highly consistent trends with kVp for each combination of breast density and thickness. The optimized kVp ranged from 26 kVp for 2 cm 100% adipose breasts to 30 kVp for 8 cm 100% glandular breasts. The use of the optimized W–Rh technique compared to standard Mo–Mo techniques provided dose savings ranging from 9% for 2 cm thick, 100% adipose breasts, to 63% for 6 cm thick, 100% glandular breasts, and for breasts with a 50% adipose∕50% glandular composition, from 12% for 2 cm thick breasts up to 57% for 8 cm thick breasts. PMID:20384232

  13. A technique optimization protocol and the potential for dose reduction in digital mammography

    SciTech Connect

    Ranger, Nicole T.; Lo, Joseph Y.; Samei, Ehsan

    2010-03-15

    Digital mammography requires revisiting techniques that have been optimized for prior screen/film mammography systems. The objective of the study was to determine optimized radiographic technique for a digital mammography system and demonstrate the potential for dose reduction in comparison to the clinically established techniques based on screen- film. An objective figure of merit (FOM) was employed to evaluate a direct-conversion amorphous selenium (a-Se) FFDM system (Siemens Mammomat Novation{sup DR}, Siemens AG Medical Solutions, Erlangen, Germany) and was derived from the quotient of the squared signal-difference-to-noise ratio to mean glandular dose, for various combinations of technique factors and breast phantom configurations including kilovoltage settings (23-35 kVp), target/filter combinations (Mo-Mo and W-Rh), breast-equivalent plastic in various thicknesses (2-8 cm) and densities (100% adipose, 50% adipose/50% glandular, and 100% glandular), and simulated mass and calcification lesions. When using a W-Rh spectrum, the optimized FOM results for the simulated mass and calcification lesions showed highly consistent trends with kVp for each combination of breast density and thickness. The optimized kVp ranged from 26 kVp for 2 cm 100% adipose breasts to 30 kVp for 8 cm 100% glandular breasts. The use of the optimized W-Rh technique compared to standard Mo-Mo techniques provided dose savings ranging from 9% for 2 cm thick, 100% adipose breasts, to 63% for 6 cm thick, 100% glandular breasts, and for breasts with a 50% adipose/50% glandular composition, from 12% for 2 cm thick breasts up to 57% for 8 cm thick breasts.

  14. Reduction Kinetics of Graphene Oxide Determined by Temperature Programmed Desorption

    NASA Astrophysics Data System (ADS)

    Ventrice, Carl; Clark, Nicholas; Field, Daniel; Geisler, Heike; Jung, Inhwa; Yang, Dongxing; Piner, Richard; Ruoff, Rodney

    2009-10-01

    Graphene oxide, which is an electrical insulator, shows promise for use in several technological applications such as dielectric layers in nanoscale electronic devices or as the active region of chemical sensors. In principle, graphene oxide films could also be used as a precursor for the formation of large-scale graphene films by either thermal or chemical reduction of the graphene oxide. In order to determine the thermal stability and reduction kinetics of graphene oxide, temperature program desorption (TPD) measurements have been performed on multilayer films of graphene oxide deposited on SiO2/Si(100) substrates. The graphene oxide was exfoliated from the graphite oxide source material by slow-stirring in aqueous solution, which produces single-layer platelets with an average lateral size of ˜10 μm. From the TPD measurements, it was determined that the decomposition process begins at ˜80 ^oC. The primary desorption products of the graphene oxide films for temperatures up to 300 ^oC are H2O, CO2, and CO, with only trace amounts of O2 being detected. An activation energy of 1.4 eV/molecule was determined by assuming an Arrhenius dependence for the decomposition process.

  15. Transplantation Dose Alters the Differentiation Program of Hematopoietic Stem Cells.

    PubMed

    Brewer, Casey; Chu, Elizabeth; Chin, Mike; Lu, Rong

    2016-05-24

    Hematopoietic stem cell (HSC) transplantation is the most prevalent stem cell therapy, but it remains a risky procedure. To improve this treatment, it is important to understand how transplanted stem cells rebuild the blood and immune systems and how this process is impacted by transplantation variables such as the HSC dose. Here, we find that, in the long term following transplantation, 70%-80% of donor-HSC-derived clones do not produce all measured blood cell types. High HSC doses lead to more clones that exhibit balanced lymphocyte production, whereas low doses produce more T-cell-specialized clones. High HSC doses also produce significantly higher proportions of early-differentiating clones compared to low doses. These complex differentiation behaviors uncover the clonal-level regeneration dynamics of hematopoietic regeneration and suggest that transplantation dose can be exploited to improve stem cell therapy. PMID:27184851

  16. An Interactive Point Kernel Program For Photon Dose Rate Prediction of Cylindrical Source/Shield Arrangements.

    Energy Science and Technology Software Center (ESTSC)

    1990-10-26

    Version 00 The program ZYLIND is an interactive point kernel program for photon dose rate prediction of a homogeneous cylindrical source shielded by cylindrical (radial) or plane (axial) layered shields.

  17. Computerized fluoroscopy with zero-dose image updates for minimally invasive femoral diaphyseal fracture reduction

    NASA Astrophysics Data System (ADS)

    Zheng, Guoyan; Dong, Xiao

    2006-03-01

    In this paper, a computerized fluoroscopy with zero-dose image updates for femoral diaphyseal fracture reduction is proposed. It is achieved with a two-step procedure. Starting from a few (normally 2) calibrated fluoroscopic image, the first step, data preparation, automatically estimates the size and the pose of the diaphyseal fragments through three-dimensional morphable object fitting using a parametric cylinder model. The projection boundary of each estimated cylinder, a quadrilateral, is then fed to a region information based active contour model to extract the fragment contours from the input fluoroscopic images. After that, each point on the contour is interpolated relative to the four vertices of the corresponding quadrilateral, which resulted in four interpolation coefficients per point. The second step, image updates, repositions the fragment projection on each acquired image during bony manipulation using a computerized method. It starts with interpolation of the new position of each point on the fragment contour using the interpolation coefficients calculated in the first step and the new position of the corresponding quadrilateral. The position of the quadrilateral is updated in real time according to the positional changes of the associated bone fragments, as determined by the navigation system during fracture reduction. The newly calculated image coordinates of the fragment contour are then fed to a OpenGL® based texture warping pipeline to achieve a real-time image updates. The presented method provides a realistic augmented reality for the surgeon. Its application may result in great reduction of the X-ray radiation to the patient and to the surgical team.

  18. The influence of acute kidney injury on antimicrobial dosing in critically ill patients: are dose reductions always necessary?

    PubMed

    Blot, Stijn; Lipman, Jeffrey; Roberts, Darren M; Roberts, Jason A

    2014-05-01

    Optimal dosing of antimicrobial therapy is pivotal to increase the likelihood of survival in critically ill patients with sepsis. Drug exposure that maximizes bacterial killing, minimizes the development of antimicrobial resistance, and avoids concentration-related toxicities should be considered the target of therapy. However, antimicrobial dosing is problematic as pathophysiological factors inherent to sepsis that alter may result in reduced concentrations. Alternatively, sepsis may evolve to multiple-organ dysfunction including acute kidney injury (AKI). In this case, decreased clearance of renally cleared drugs is possible, which may lead to increased concentrations that may cause drug toxicities. Consequently, when dosing antibiotics in septic patients with AKI, one should consider factors that may lead to underdosing and overdosing. Drug-specific pharmacokinetic and pharmacodynamic data may be helpful to guide dosing in these circumstances. Yet, because of the high interpatient variability in pharmacokinetics of antibiotics during sepsis, this issue remains a significant challenge. PMID:24602849

  19. SU-C-12A-07: Effect of Vertical Position On Dose Reduction Using X-Care

    SciTech Connect

    Silosky, M; Marsh, R

    2014-06-01

    Purpose: Reduction of absorbed dose to radiosensitive tissues is an important goal in diagnostic radiology. Siemens Medical has introduced a technique (X-CARE) to lower CT dose to anterior anatomy by reducing the tube current during 80° of rotation over radiosensitive tissues. Phantom studies have shown 30-40% dose reduction when phantoms are positioned at isocenter. However, for CT face and sinus exams, the center of the head is commonly positioned below isocenter. This work investigated the effects of vertical patient positioning on dose reduction using X-CARE. Methods: A 16cm Computed Tomography Dose Index phantom was scanned on a Siemens Definition Flash CT scanner using a routine head protocol, with the phantom positioned at scanner isocenter. Optically stimulated luminescent dosimeters were placed on the anterior and posterior sides of the phantom. The phantom was lowered in increments of 2cm and rescanned, up to 8cm below isocenter. The experiment was then repeated using the same scan parameters but adding the X-CARE technique. The mean dosimeter counts were determined for each phantom position, and the difference between XCARE and routine scans was plotted as a function of distance from isocenter. Results: With the phantom positioned at isocenter, using XCARE reduced dose to the anterior side of the phantom by 40%, compared to dose when X-CARE was not used. Positioned below isocenter, anterior dose was reduced by only 20-27%. Additionally, using X-CARE at isocenter reduced dose to the anterior portion of the phantom by 45.6% compared to scans performed without X-CARE 8cm below isocenter. Conclusion: While using X-CARE substantially reduced dose to the anterior side of the phantom, this effect was diminished when the phantom was positioned below isocenter, simulating common practice for face and sinus scans. This indicates that centering the head in the gantry will maximize the effect of X-CARE.

  20. Sex differences in nicotine self-administration in rats during progressive unit dose reduction: implications for nicotine regulation policy.

    PubMed

    Grebenstein, Patricia; Burroughs, Danielle; Zhang, Yan; LeSage, Mark G

    2013-12-01

    Reducing the nicotine content in tobacco products is being considered by the FDA as a policy to reduce the addictiveness of tobacco products. Understanding individual differences in response to nicotine reduction will be critical to developing safe and effective policy. Animal and human research demonstrating sex differences in the reinforcing effects of nicotine suggests that males and females may respond differently to nicotine-reduction policies. However, no studies have directly examined sex differences in the effects of nicotine unit-dose reduction on nicotine self-administration (NSA) in animals. The purpose of the present study was to examine this issue in a rodent self-administration model. Male and female rats were trained to self-administer nicotine (0.06mg/kg) under an FR 3 schedule during daily 23h sessions. Rats were then exposed to saline extinction and reacquisition of NSA, followed by weekly reductions in the unit dose (0.03 to 0.00025mg/kg) until extinction levels of responding were achieved. Males and females were compared with respect to baseline levels of intake, resistance to extinction, degree of compensatory increases in responding during dose reduction, and the threshold reinforcing unit dose of nicotine. Exponential demand-curve analysis was also conducted to compare the sensitivity of males and females to increases in the unit price (FR/unit dose) of nicotine (i.e., elasticity of demand or reinforcing efficacy). Females exhibited significantly higher baseline intake and less compensation than males. However, there were no sex differences in the reinforcement threshold or elasticity of demand. Dose-response relationships were very well described by the exponential demand function (r(2) values>0.96 for individual subjects). These findings suggest that females may exhibit less compensatory smoking in response to nicotine reduction policies, even though their nicotine reinforcement threshold and elasticity of demand may not differ from males

  1. 76 FR 70408 - Information Collection; Understanding Value Trade-Offs Regarding Fire Hazard Reduction Programs...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-14

    ... Forest Service Information Collection; Understanding Value Trade-Offs Regarding Fire Hazard Reduction... approved information collection, Understanding Value Trade-offs Regarding Fire Hazard Reduction Programs in...-offs Regarding Fire Hazard Reduction Programs in the Wildland-Urban Interface. OMB Number:...

  2. Hanford Dose Overview Program. Comparison of AIRDOS-EPA and Hanford site dose codes

    SciTech Connect

    Aaberg, R.L.; Napier, B.A.

    1985-11-01

    Radiation dose commitments for persons in the Hanford environs calculated using AIRDOS-EPA were compared with those calculated using a suite of Hanford codes: FOOD, PABLM, DACRIN, and KRONIC. Dose commitments to the population and to the maximally exposed individual (MI) based on annual releases of eight radionuclides from the N-Reactor, were calculated by these codes. Dose commitments from each pathway to the total body, lung, thyroid, and lower large intestine (LLI) are given for the population and MI, respectively. 11 refs., 25 tabs.

  3. Dose reduction using prior image constrained compressed sensing (DR-PICCS)

    NASA Astrophysics Data System (ADS)

    Tang, Jie; Thériault Lauzier, Pascal; Chen, Guang-Hong

    2011-03-01

    A technique for dose reduction using prior image constrained compressed sensing (DR-PICCS) in computed tomography (CT) is proposed in this work. In DR-PICCS, a standard FBP reconstructed image is forward projected to get a fully sampled projection data set. Meanwhile, it is low-pass filtered and used as the prior image in the PICCS reconstruction framework. Next, the prior image and the forward projection data are used together by the PICCS algorithm to obtain a low noise DR-PICCS reconstruction, which maintains the spatial resolution of the original FBP images. The spatial resolution of DR-PICCS was studied using a Catphan phantom by MTF measurement. The noise reduction factor, CT number change and noise texture were studied using human subject data consisting of 20 CT colonography exams performed under an IRB-approved protocol. In each human subject study, six ROIs (two soft tissue, two colonic air columns, and two subcutaneous fat) were selected for the CT number and noise measurements study. Skewness and kurtosis were used as figures of merit to indicate the noise texture. A Bland-Altman analysis was performed to study the accuracy of the CT number. The results showed that, compared with FBP reconstructions, the MTF curve shows very little change in DR-PICCS reconstructions, spatial resolution loss is less than 0.1 lp/cm, and the noise standard deviation can be reduced by a factor of 3 with DR-PICCS. The CT numbers in FBP and DR-PICCS reconstructions agree well, which indicates that DR-PICCS does not change CT numbers. The noise textures indicators measured from DR-PICCS images are in a similar range as FBP images.

  4. WASTE REDUCTION OF TECHNOLOGY EVALUATIONS OF THE U.S. EPA WRITE PROGRAM

    EPA Science Inventory

    The Waste Reduction Innovative Technology Evaluation (WRITE)Program was established in 1989 to provide objective, accurate performance and cost data about waste reducing technologies for a variety of industrial and commercial application. EPA's Risk Reduction Engineering Laborato...

  5. WASTE REDUCTION TECHNOLOGY EVALUATIONS OF THE U.S. EPA WRITE PROGRAM

    EPA Science Inventory

    The Waste Reduction Innovative Technology Evaluation (WRITE) Program was established in 1989 to provide objective, accurate performance and cost data about waste reducing technologies for a variety of industrial and commercial applications. PA's Risk Reduction Engineering Laborat...

  6. Special Diabetes Program for Indians: Retention in Cardiovascular Risk Reduction

    PubMed Central

    Manson, Spero M.; Jiang, Luohua; Zhang, Lijing; Beals, Janette; Acton, Kelly J.; Roubideaux, Yvette

    2011-01-01

    Purpose: This study examined the associations between participant and site characteristics and retention in a multisite cardiovascular disease risk reduction project. Design and Methods: Data were derived from the Special Diabetes Program for Indians Healthy Heart Demonstration Project, an intervention to reduce cardiovascular risk among American Indians and Alaska Natives with diabetes. In 2006, a total of 1,072 participants from 30 participating sites completed baseline questionnaires measuring demographics and sociobehavioral factors. They also underwent a medical examination at baseline and were reassessed annually after baseline. A Provider Annual Questionnaire was administered to staff members of each grantee site at the end of each year to assess site characteristics. Generalized estimating equation models were used to evaluate the relationships between participant and site characteristics and retention 1 year after baseline. Results: Among enrolled participants, 792 (74%) completed their first annual assessment. Participants who completed the first annual assessment tended to be older and had, at baseline, higher body mass index and higher level of physical activity. Site characteristics associated with retention included average age of staff, proportion of female staff members, and percentage of staff members having completed graduate or professional school. Implications: Understanding successful retention must reach beyond individual characteristics of participants to include features of the settings that house the interventions. PMID:21565816

  7. Patients with Fabry Disease after Enzyme Replacement Therapy Dose Reduction and Switch-2-Year Follow-Up.

    PubMed

    Lenders, Malte; Canaan-Kühl, Sima; Krämer, Johannes; Duning, Thomas; Reiermann, Stefanie; Sommer, Claudia; Stypmann, Jörg; Blaschke, Daniela; Üçeyler, Nurcan; Hense, Hans-Werner; Brand, Stefan-Martin; Wanner, Christoph; Weidemann, Frank; Brand, Eva

    2016-03-01

    Because of the shortage of agalsidase-β supply between 2009 and 2012, patients with Fabry disease either were treated with reduced doses or were switched to agalsidase-α. In this observational study, we assessed end organ damage and clinical symptoms with special focus on renal outcome after 2 years of dose-reduction and/or switch to agalsidase-α. A total of 89 adult patients with Fabry disease who had received agalsidase-β (1.0 mg/kg body wt) for >1 year were nonrandomly assigned to continue this treatment regimen (regular-dose group, n=24), to receive a reduced dose of 0.3-0.5 mg/kg and a subsequent switch to 0.2 mg/kg agalsidase-α (dose-reduction-switch group, n=28), or to directly switch to 0.2 mg/kg agalsidase-α (switch group, n=37) and were followed-up for 2 years. We assessed clinical events (death, myocardial infarction, severe arrhythmia, stroke, progression to ESRD), changes in cardiac and renal function, Fabry-related symptoms (pain, hypohidrosis, diarrhea), and disease severity scores. Determination of renal function by creatinine and cystatin C-based eGFR revealed decreasing eGFRs in the dose-reduction-switch group and the switch group. The Mainz Severity Score Index increased significantly in these two groups (P=0.02 and P<0.001, respectively), and higher frequencies of gastrointestinal pain occurred during follow-up. In conclusion, after 2 years of observation, all groups showed a stable clinical disease course with respect to serious clinical events. However, patients under agalsidase-β dose-reduction and switch or a direct switch to agalsidase-α showed a decline of renal function independent of the eGFR formula used. PMID:26185201

  8. Postimplantation Analysis Enables Improvement of Dose-Volume Histograms and Reduction of Toxicity for Permanent Seed Implantation

    SciTech Connect

    Wust, Peter Postrach, Johanna; Kahmann, Frank; Henkel, Thomas; Graf, Reinhold; Cho, Chie Hee; Budach, Volker; Boehmer, Dirk

    2008-05-01

    Purpose: To demonstrate how postimplantation analysis is useful for improving permanent seed implantation and reducing toxicity. Patients and Methods: We evaluated 197 questionnaires completed by patients after permanent seed implantation (monotherapy between 1999 and 2003). For 70% of these patients, a computed tomography was available to perform postimplantation analysis. The index doses and volumes of the dose-volume histograms (DVHs) were determined and categorized with respect to the date of implantation. Differences in symptom scores relative to pretherapeutic status were analyzed with regard to follow-up times and DVH descriptors. Acute and subacute toxicities in a control group of 117 patients from an earlier study (June 1999 to September 2001) by Wust et al. (2004) were compared with a matched subgroup from this study equaling 110 patients treated between October 2001 and August 2003. Results: Improved performance, identifying a characteristic time dependency of DVH parameters (after implantation) and toxicity scores, was demonstrated. Although coverage (volume covered by 100% of the prescription dose of the prostate) increased slightly, high-dose regions decreased with the growing experience of the users. Improvement in the DVH and a reduction of toxicities were found in the patient group implanted in the later period. A decline in symptoms with follow-up time counteracts this gain of experience and must be considered. Urinary and sexual discomfort was enhanced by dose heterogeneities (e.g., dose covering 10% of the prostate volume, volume covered by 200% of prescription dose). In contrast, rectal toxicities correlated with exposed rectal volumes, especially the rectal volume covered by 100% of the prescription dose. Conclusion: The typical side effects occurring after permanent seed implantation can be reduced by improving the dose distributions. An improvement in dose distributions and a reduction of toxicities were identified with elapsed time between

  9. Sex differences in nicotine self-administration in rats during progressive unit dose reduction: Implications for nicotine regulation policy

    PubMed Central

    Grebenstein, Patricia; Burroughs, Danielle; Zhang, Yan; LeSage, Mark G.

    2013-01-01

    Reducing the nicotine content in tobacco products is being considered by the FDA as a policy to reduce the addictiveness of tobacco products. Understanding individual differences in response to nicotine reduction will be critical to developing safe and effective policy. Animal and human research demonstrating sex differences in the reinforcing effects of nicotine suggests that males and females may respond differently to nicotine-reduction policies. However, no studies have directly examined sex differences in the effects of nicotine unit-dose reduction on nicotine self-administration (NSA) in animals. The purpose of the present study was to examine this issue in a rodent self-administration model. Male and female rats were trained to self-administer nicotine (0.06 mg/kg) under an FR 3 schedule during daily 23 h sessions. Rats were then exposed to saline extinction and reacquisition of NSA, followed by weekly reductions in the unit dose (0.03 to 0.00025 mg/kg) until extinction levels of responding were achieved. Males and females were compared with respect to baseline levels of intake, resistance to extinction, degree of compensatory increases in responding during dose reduction, and the threshold reinforcing unit dose of nicotine. Exponential demand-curve analysis was also conducted to compare the sensitivity of males and females to increases in the unit price (FR/unit dose) of nicotine (i.e., elasticity of demand or reinforcing efficacy). Females exhibited significantly higher baseline intake and less compensation than males. However, there were no sex differences in the reinforcement threshold or elasticity of demand. Dose–response relationships were very well described by the exponential demand function (r2 values > 0.96 for individual subjects). These findings suggest that females may exhibit less compensatory smoking in response to nicotine reduction policies, even though their nicotine reinforcement threshold and elasticity of demand may not differ from

  10. Radiation Dose Reduction in Pediatric Body CT Using Iterative Reconstruction and a Novel Image-Based Denoising Method

    PubMed Central

    Yu, Lifeng; Fletcher, Joel G.; Shiung, Maria; Thomas, Kristen B.; Matsumoto, Jane M.; Zingula, Shannon N.; McCollough, Cynthia H.

    2016-01-01

    OBJECTIVE The objective of this study was to evaluate the radiation dose reduction potential of a novel image-based denoising technique in pediatric abdominopelvic and chest CT examinations and compare it with a commercial iterative reconstruction method. MATERIALS AND METHODS Data were retrospectively collected from 50 (25 abdominopelvic and 25 chest) clinically indicated pediatric CT examinations. For each examination, a validated noise-insertion tool was used to simulate half-dose data, which were reconstructed using filtered back-projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) methods. A newly developed denoising technique, adaptive nonlocal means (aNLM), was also applied. For each of the 50 patients, three pediatric radiologists evaluated four datasets: full dose plus FBP, half dose plus FBP, half dose plus SAFIRE, and half dose plus aNLM. For each examination, the order of preference for the four datasets was ranked. The organ-specific diagnosis and diagnostic confidence for five primary organs were recorded. RESULTS The mean (± SD) volume CT dose index for the full-dose scan was 5.3 ± 2.1 mGy for abdominopelvic examinations and 2.4 ± 1.1 mGy for chest examinations. For abdominopelvic examinations, there was no statistically significant difference between the half dose plus aNLM dataset and the full dose plus FBP dataset (3.6 ± 1.0 vs 3.6 ± 0.9, respectively; p = 0.52), and aNLM performed better than SAFIRE. For chest examinations, there was no statistically significant difference between the half dose plus SAFIRE and the full dose plus FBP (4.1 ± 0.6 vs 4.2 ± 0.6, respectively; p = 0.67), and SAFIRE performed better than aNLM. For all organs, there was more than 85% agreement in organ-specific diagnosis among the three half-dose configurations and the full dose plus FBP configuration. CONCLUSION Although a novel image-based denoising technique performed better than a commercial iterative reconstruction method in pediatric

  11. Level of radiation dose in university hospital noninsured private health screening programs in Korea

    PubMed Central

    2016-01-01

    Objectives The aim of this study is to evaluate radiation exposure resulting from the comprehensive health examinations of selected university hospital programs and to present basic data for research and management strategies on the health effects of medical radiation exposure. Methods Radiation-based diagnostic studies of the comprehensive health examination programs of ten university hospitals in Seoul, Korea, as introduced in their websites, were analyzed. The medical radiation studies of the programs were reviewed by radiologists. Only the effective doses of the basic studies were included in the analysis. The optional studies of the programs were excluded. Results Among the 190 comprehensive health examination programs, 132 programs (69.5%) included computed tomography studies, with an average of 1.4 scans. The average effective dose of radiation by program was 3.62 mSv for an intensive program for specific diseases; 11.12 mSv for an intensive program for cancer; 18.14 mSv for a premium program; and 24.08 mSv for an overnight program. A higher cost of a programs was linked to a higher effective dose (r=0.812). The effective doses of the examination programs for the same purposes differed by as much as 2.1 times by hospital. Inclusion of positron emission tomography–computed tomography was the most critical factor in determining the level of effective dose. Conclusions It was found that radiation exposure dose from comprehensive health exam programs targeted for an asymptomatic, healthy public reached between 3.6 and 24 times the annual dose limit for the general public. Relevant management policies at the national level should be provided to minimize medical radiation exposure. PMID:27032387

  12. Development of an online automatic computed radiography dose data mining program: a preliminary study.

    PubMed

    Ng, Curtise K C; Sun, Zhonghua

    2010-01-01

    Recent studies have reported the computed radiography (CR) dose creep problem and therefore the need to have monitoring processes in place in clinical departments. The objective of this study is to provide a better technological solution to implement a regular CR dose monitoring process. An online automatic CR dose data mining program which can be applied to different systems was developed based on freeware and existing softwares in the Picture Archiving and Communication System (PACS) server. The program was tested with 69 CR images. This preliminary study shows that the program addresses the major weaknesses of some existing studies including involvement of manual procedures in the monitoring process and being only applicable to a single manufacturer's CR images. The proposed method provides an efficient and effective solution to implement a CR dose monitoring program regularly in busy clinical departments to regulate the dose creep problem so as to reinforce the 'As Low As Reasonably Achievable' (ALARA) principle. PMID:19640604

  13. Occupational dose reduction at Department of Energy contractor facilities: Bibliography of selected readings in radiation protection and ALARA

    SciTech Connect

    Dionne, B.J.; Sullivan, S.G.; Baum, J.W.

    1993-12-01

    This bibliography contains abstracts relating to various aspects of ALARA program implementation and dose reduction activities, with a focus on DOE facilities. Abstracts included in this bibliography were selected from proceedings of technical meetings, journals, research reports, searches of the DOE Energy, Science and Technology Database (in general, the citation and abstract information is presented as obtained from this database), and reprints of published articles provided by the authors. Facility types and activities covered in the scope of this report include: radioactive waste, uranium enrichment, fuel fabrication, spent fuel storage and reprocessing, facility decommissioning, hot laboratories, tritium production, research, test and production reactors, weapons fabrication and testing, fusion, uranium and plutonium processing, radiography, and aocelerators. Information on improved shielding design, decontamination, containments, robotics, source prevention and control, job planning, improved operational and design techniques, as well as on other topics, has been included. In addition, DOE/EH reports not included in previous volumes of the bibliography are in this volume (abstracts 611 to 684). This volume (Volume 5 of the series) contains 217 abstracts. An author index and a subject index are provided to facilitate use. Both indices contain the abstract numbers from previous volumes, as well as the current volume. Information that the reader feels might be included in the next volume of this bibliography should be submitted to the BNL ALARA Center.

  14. PABLM: a computer program to calculate accumulated radiation doses from radionuclides in the environment

    SciTech Connect

    Napier, B.A.; Kennedy, W.E. Jr.; Soldat, J.K.

    1980-03-01

    A computer program, PABLM, was written to facilitate the calculation of internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. This report contains details of mathematical models used and calculational procedures required to run the computer program. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides in the environment after the releases have ended. Radioactive decay is considered during the release of radionuclides, after they are deposited on the plants or ground, and during holdup of food after harvest. The radiation dose models consider several exposure pathways. Doses may be calculated for either a maximum-exposed individual or for a population group. The doses calculated are accumulated doses from continuous chronic exposure. A first-year committed dose is calculated as well as an integrated dose for a selected number of years. The equations for calculating internal radiation doses are derived from those given by the International Commission on Radiological Protection (ICRP) for body burdens and MPC's of each radionuclide. The radiation doses from external exposure to contaminated water and soil are calculated using the basic assumption that the contaminated medium is large enough to be considered an infinite volume or plane relative to the range of the emitted radiations. The equations for calculations of the radiation dose from external exposure to shoreline sediments include a correction for the finite width of the contaminated beach.

  15. Reduced z-axis technique for CT Pulmonary angiography in pregnancy--validation for practical use and dose reduction.

    PubMed

    Shahir, Kaushik; McCrea, Jonathan M; Lozano, Luis Antonio Sosa; Goodman, Lawrence R

    2015-12-01

    The aim of this study is to determine the feasibility of using reduced scan range CT pulmonary angiography technique in pregnancy for pulmonary embolism (PE) and to quantify resulting dose reduction. This was a retrospective study. Eighty-four CTPA exams performed on pregnant women during 2004-2012. The scans were modified to create reduced anatomic coverage scans extending from aortic arch to base of heart. These were separately evaluated by two radiologists for PE and non-PE abnormalities. The results were then compared by the third radiologist with original radiology report and scans. Radiation dose reduction was evaluated prospectively in 36 patients as part of a quality control project. Two patients had PE and were successfully identified on reduced z-axis scans. Thirty-two exams were normal; rest had 60 pertinent and 16 had incidental findings. There were four incidental findings which included three benign thyroid nodules and one benign small lung nodule which were missed. None of these affected clinical outcome or management. There was 71 % radiation dose reduction. No PE or any important diagnoses are missed using reduced z-axis CTPA in pregnancy. There is a substantial radiation dose reduction. Hence, this technique is highly recommended in pregnancy. PMID:26304188

  16. Effects of shielding the radiosensitive superficial organs of ORNL pediatric phantoms on dose reduction in computed tomography

    PubMed Central

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

    2014-01-01

    In computed tomography (CT), some superficial organs which have increased sensitivity to radiation, receive doses that are significant enough to be matter of concern. Therefore, in this study, the effects of using shields on the amount of dose reduction and image quality was investigated for pediatric imaging. Absorbed doses of breasts, eyes, thyroid and testes of a series of pediatric phantoms without and with different thickness of bismuth and lead were calculated by Monte Carlo simulation. Appropriate thicknesses of shields were chosen based on their weights, X-ray spectrum, and the amount of dose reduction. In addition, the effect of lead shield on image quality of a simple phantom was assessed quantitatively using region of interest (ROI) measurements. Considering the maximum reduction in absorbed doses and X-ray spectrum, using a lead shield with a maximum thickness of 0.4 mm would be appropriate for testes and thyroid and two other organs (which are exposed directly) should be protected with thinner shields. Moreover, the image quality assessment showed that lead was associated with significant increases in both noise and CT attenuation values, especially in the anterior of the phantom. Overall, the results suggested that shielding is a useful optimization tool in CT. PMID:25525312

  17. Dose reduction of up to 89% while maintaining image quality in cardiovascular CT achieved with prospective ECG gating

    NASA Astrophysics Data System (ADS)

    Londt, John H.; Shreter, Uri; Vass, Melissa; Hsieh, Jiang; Ge, Zhanyu; Adda, Olivier; Dowe, David A.; Sabllayrolles, Jean-Louis

    2007-03-01

    We present the results of dose and image quality performance evaluation of a novel, prospective ECG-gated Coronary CT Angiography acquisition mode (SnapShot Pulse, LightSpeed VCT-XT scanner, GE Healthcare, Waukesha, WI), and compare it to conventional retrospective ECG gated helical acquisition in clinical and phantom studies. Image quality phantoms were used to measure noise, slice sensitivity profile, in-plane resolution, low contrast detectability and dose, using the two acquisition modes. Clinical image quality and diagnostic confidence were evaluated in a study of 31 patients scanned with the two acquisition modes. Radiation dose reduction in clinical practice was evaluated by tracking 120 consecutive patients scanned with the prospectively gated scan mode. In the phantom measurements, the prospectively gated mode resulted in equivalent or better image quality measures at dose reductions of up to 89% compared to non-ECG modulated conventional helical scans. In the clinical study, image quality was rated excellent by expert radiologist reviewing the cases, with pathology being identical using the two acquisition modes. The average dose to patients in the clinical practice study was 5.6 mSv, representing 50% reduction compared to a similar patient population scanned with the conventional helical mode.

  18. SLI Complex Curvature Friction Stir Weld Risk Reduction Program

    NASA Technical Reports Server (NTRS)

    Hartley, Paula J.; Schneider, Jules; Jones, Chip; Lawless, Kirby; Russell, Carolyn

    2003-01-01

    The Space Launch Initiative Program (SLI) in conjunction with the National Center for Advanced Manufacturing (NCAM) will demonstrate the ability to produce large-scale complex curvature hardware using the self-reacting friction stir welding process. This multi-phased risk reduction program includes friction stir welding process development and manufacture of a 22-ft diameter quarter dome using a conventional tooling approach; it culminates in a 27.5-ft diameter quarter dome demonstration performed on a 5-axis Universal Weld System. The design, fabrication, and installation of the Universal Weld System is made possible through a collaboration between the State of Louisiana, NASA, and the University of New Orleans. The Universal Weld System, manufactured by MTS Systems Corporation, will be installed at the Michoud Assembly Facility in New Orleans, Louisiana, and will be capable of manufacturing domes up to 30 ft in diameter. All welding will be accomplished using the Adaptable Adjustable Pin Tool (AdAPT) weld head and controller manufactured by MTS. Weld parameters will be developed for an aluminum alloy in gauges ranging from 0.320 to 0.400 in. thick. Weld quality will be verified through radiography, mechanical property testing at ambient and LN2 temperatures, and metallurgical analysis. The AdAPT weld head will then be mounted on a 22-ft diameter dome tool, which will be modified to include a welding track and drive system for moving the AdAPT weld head along the weld joint. This tool will then be used to manufacture a 22-ft diameter dome of an aluminum alloy, with 0.320-in. constant thickness joints, consisting of three individual gore panels. Finally, the 27.5-ft diameter quarter dome will be welded on the Universal Weld System. The quarter dome will consist of three individual gore panels with weld lands tapering from 0.320 to 0.360 in. in thickness. With the demonstration of these welds, the ability to manufacture large diameter domes using the friction stir

  19. DITTY - a computer program for calculating population dose integrated over ten thousand years

    SciTech Connect

    Napier, B.A.; Peloquin, R.A.; Strenge, D.L.

    1986-03-01

    The computer program DITTY (Dose Integrated Over Ten Thousand Years) was developed to determine the collective dose from long term nuclear waste disposal sites resulting from the ground-water pathways. DITTY estimates the time integral of collective dose over a ten-thousand-year period for time-variant radionuclide releases to surface waters, wells, or the atmosphere. This document includes the following information on DITTY: a description of the mathematical models, program designs, data file requirements, input preparation, output interpretations, sample problems, and program-generated diagnostic messages.

  20. Dose combinations of exendin-4 and salmon calcitonin produce additive and synergistic reductions in food intake in nonhuman primates

    PubMed Central

    Kemm, Matthew H.; Ofeldt, Erica M.; Moran, Timothy H.

    2010-01-01

    Glucagon-like peptide-1 (GLP-1) and amylin mediate the feedback control of eating by seemingly separate, but overlapping mechanisms. This study examined the effects of combined doses of the GLP-1 agonist, exendin-4 (Ex-4), and the amylin analog, salmon calcitonin (sCT), on food intake and meal patterns in adult male rhesus monkeys. Monkeys received intramuscular injections of Ex-4 (0, 0.1, 0.32, or 0.56 μg/kg), sCT (0, 0.1, or 0.32 μg/kg), or combinations thereof before a 6-h daily access to food. Dose combinations produced reductions in food intake that were significantly greater than those produced by the individual doses. Surface plots of the hourly intake indicated a synergistic interaction at lower doses of Ex-4 and sCT during the first 4 h of feeding and additive effects at hours 5 and 6. Meal pattern analysis revealed the combinational doses reduced average meal size and meal frequency by additive interactions, whereas infra-additive effects were apparent at lower doses for first meal size. Combinational doses were further characterized by administration of repeated daily injections of 0.56 μg/kg Ex-4 + 0.32 μg/kg sCT for 5 days. This resulted in sustained reductions in daily food intake (>70% from saline baseline) for 5 days with residual reductions (∼48% from saline baseline) persisting on day 1 following the injections. In contrast, when pair-fed an identical amount of daily food, there was a compensatory food intake increase on day 1 following the pair-feeding (∼132% of saline baseline). Such data suggest Ex-4 and sCT interact in an overall additive fashion to reduce food intake and further the understanding of how GLP-1 and amylin agonist combinations influence feeding behavior. PMID:20554932

  1. SU-E-I-37: Eye Lens Dose Reduction From CT Scan Using Organ Based Tube Current Modulation

    SciTech Connect

    Liu, H; Liu, T; Xu, X; Wu, J; Zhuo, W

    2015-06-15

    Purpose: To investigate the eye lens dose reduction by CT scan with organ based tube current modulation (OBTCM) using GPU Monte Carlo code ARCHER-CT. Methods: 36 X-ray sources and bowtie filters were placed around the patient head with the projection angle interval of 10° for one rotation of CT scan, each projection was simulated respectively. The voxel eye models with high resolution(0.1mm*0.1mm*0.1mm) were used in the simulation and different tube voltage including 80kVp, 100kVp, 120kVp and 140kVp were taken into consideration. Results: The radiation doses to the eye lens increased with the tube voltage raised from 80kVp to 140kVp, and the dose results from 0° (AP) direction are much higher than those from 180° (PA) direction for all the 4 different tube voltage investigated. This 360° projection dose characteristic enables organ based TCM, which can reduce the eye lens dose by more than 55%. Conclusion: As the eye lens belongs to superficial tissues, its radiation dose to external exposure like CT is direction sensitive, and this characteristic feature makes organ based TCM to be an effective way to reduce the eye lens dose, so more clinical use of this technique were recommended. National Nature Science Foundation of China(No.11475047)

  2. OVERVIEW OF EPA'S HUMAN EXPOSURE AND SOURCE-TO-DOSE MODELING PROGRAM: HEADSUP

    EPA Science Inventory

    EPA's human exposure and source-to-dose modeling program is designed to provide a scientifically sound approach to understanding how people are actually exposed to pollutants and the magnitude of predicted exposures and dose. The objective of this research project is to develo...

  3. Program documentation for the space environment test division post-test data reduction program (GNFLEX)

    NASA Technical Reports Server (NTRS)

    Jones, L. D.

    1979-01-01

    The Space Environment Test Division Post-Test Data Reduction Program processes data from test history tapes generated on the Flexible Data System in the Space Environment Simulation Laboratory at the National Aeronautics and Space Administration/Lyndon B. Johnson Space Center. The program reads the tape's data base records to retrieve the item directory conversion file, the item capture file and the process link file to determine the active parameters. The desired parameter names are read in by lead cards after which the periodic data records are read to determine parameter data level changes. The data is considered to be compressed rather than full sample rate. Tabulations and/or a tape for generating plots may be output.

  4. Reduction of radiation dose in radiologic examination of patients with scoliosis.

    PubMed

    Hellström, G; Irstam, L; Nachemson, A

    1983-01-01

    In an attempt to reduce the radiation dose during the examination of scoliotic patients, several screen-film combinations have been compared with a conventional system used at present. Kodak's Lanex Regular screen with Kodak Ortho H film enables the dose to be reduced eight times without significant deterioration of the image quality. The dose to the mammary glands can be reduced further by a factor of five if posterior--anterior instead of anterior--posterior projection is used. PMID:6867854

  5. Comparison of different dose reduction system in computed tomography for orthodontic applications

    PubMed Central

    FANUCCI, E.; FIASCHETTI, V.; OTTRIA, L.; MATALONI, M; ACAMPORA, V.; LIONE, R.; BARLATTANI, A.; SIMONETTI, G.

    2011-01-01

    SUMMARY To correlate different CT system: MSCT (multislice computed tomography) with different acquisition parameters (100KV, 80KV), different reconstruction algorithm (ASIR) and CBCT (cone beam computed tomography) examination in terms of absorbed X-ray dose and diagnostic accuracy. 80 KV protocols compared with 100 KV protocols resulted in reduced total radiation dose without relevant loss of diagnostic image information and quality. CBCT protocols compared with 80 KV MSCT protocols resulted in reduced total radiation dose but loss of diagnostic image information and quality although no so relevant. In addition the new system applies to equipment ASIR applicable on MSCT allows 50% of the dose without compromising image quality. PMID:23285397

  6. Characterization of statistical prior image constrained compressed sensing (PICCS): II. Application to dose reduction

    SciTech Connect

    Lauzier, Pascal Theriault; Chen Guanghong

    2013-02-15

    Purpose: The ionizing radiation imparted to patients during computed tomography exams is raising concerns. This paper studies the performance of a scheme called dose reduction using prior image constrained compressed sensing (DR-PICCS). The purpose of this study is to characterize the effects of a statistical model of x-ray detection in the DR-PICCS framework and its impact on spatial resolution. Methods: Both numerical simulations with known ground truth and in vivo animal dataset were used in this study. In numerical simulations, a phantom was simulated with Poisson noise and with varying levels of eccentricity. Both the conventional filtered backprojection (FBP) and the PICCS algorithms were used to reconstruct images. In PICCS reconstructions, the prior image was generated using two different denoising methods: a simple Gaussian blur and a more advanced diffusion filter. Due to the lack of shift-invariance in nonlinear image reconstruction such as the one studied in this paper, the concept of local spatial resolution was used to study the sharpness of a reconstructed image. Specifically, a directional metric of image sharpness, the so-called pseudopoint spread function (pseudo-PSF), was employed to investigate local spatial resolution. Results: In the numerical studies, the pseudo-PSF was reduced from twice the voxel width in the prior image down to less than 1.1 times the voxel width in DR-PICCS reconstructions when the statistical model was not included. At the same noise level, when statistical weighting was used, the pseudo-PSF width in DR-PICCS reconstructed images varied between 1.5 and 0.75 times the voxel width depending on the direction along which it was measured. However, this anisotropy was largely eliminated when the prior image was generated using diffusion filtering; the pseudo-PSF width was reduced to below one voxel width in that case. In the in vivo study, a fourfold improvement in CNR was achieved while qualitatively maintaining sharpness

  7. Dose reduction and image quality assessment in MDCT using AEC (D-DOM & Z-DOM) and in-plane bismuth shielding.

    PubMed

    Lee, Kibaek; Lee, Wonho; Lee, Junhyup; Lee, Boram; Oh, Gyubum

    2010-09-01

    Since computed tomography (CT) was introduced about 40 y ago, its use has continuously grown, resulting in the increase of the CT dose. Therefore, an awareness of the CT dose and its potential complications has led to the development of several dose-reduction strategies. One of the strategies is automatic exposure control (AEC), which modulates radiation intensity depending on the patient size, z-axis thickness (Z-DOM) or angular thickness (D-DOM). Another dose-reduction method is the in-plane bismuth shield which attenuates radiation to reduce the CT doses of the tissues underneath the shield. We evaluated and compared the dose reduction and image quality of CT for various dose-reduction techniques. The result showed that both AEC and the in-plane shield reduced the CT dose effectively and the combined method of AEC and in-plane shielding reduced the CT dose more than the single use of AEC or in-plane shields. The dose reduction using Z-DOM was normally higher than that using D-DOM. The image quality of CT dramatically degraded when the in-plane shield was directly attached to the phantom without using AEC. In order to effectively reduce CT dose without the significant degradation of the image quality, the in-plane shield should be placed 1 cm apart from the patient with applying AEC control. PMID:20511402

  8. Noise reduction by projection direction dependent diffusion for low dose fan-beam x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Tang, Shaojie; Mou, Xuanqin; Zhang, Yanbo; Yu, Hengyong

    2011-03-01

    We propose a novel method to reduce the noise in fan-beam computed tomography (CT) imaging. First, the inverse Radon transform is induced for a family of differential expression of projection function. Second, the diffusion partial differential equation (PDE) is generalized from image space to projection space in parallel-beam geometry. Third, the diffusion PDE is further induced from parallel-beam geometry to fan-beam geometry. Finally, the projection direction dependent diffusion is developed to reduce CT noise, which arises from the quantum variation in the low dose exposure of a medical x-ray CT (XCT) system. The proposed noise reduction processes projections iteratively and dependently on x-ray path position, followed by a general CT reconstruction. Numerical simulation studies have demonstrated its feasibility in the noise reduction of low dose fan-beam XCT imaging.

  9. Effect of rare earth filtration on patient exposure, dose reduction, and image quality in oral panoramic radiology

    SciTech Connect

    Tyndall, D.A.; Washburn, D.B.

    1987-01-01

    Rare earth intensifying screen material (Gd2O2S:Tb) was added to the standard Al filtration of an oral panoramic x-ray unit, resulting in a beam capable of achieving reductions in patient dose without a loss of image quality. The added rare earth filtration technique resulted in patient dose reductions of 21-56%, depending on anatomic sites, when compared to the conventional Al filtration technique. Films generated from both techniques were measured densitometrically and evaluated by a panel of practicing clinicians. Diagnostically significant differences were minimal. The results indicate that use of rare earth filters in oral panoramic radiography is an effective means of reducing exposures of dental patients to ionizing radiation.

  10. SIRHEN : a data reduction program for photonic Doppler velocimetry measurements.

    SciTech Connect

    Dolan, Daniel H., III; Ao, Tommy

    2010-06-01

    SIRHEN (Sandia InfraRed HEtrodyne aNalysis) is a program for reducing data from photonic Doppler velocimetry (PDV) measurements. SIRHEN uses the short-time Fourier transform method to extract velocity information. The program can be run in MATLAB (2008b or later) or as a Windows executable. This report describes the new Sandia InfraRed HEtrodyne aNalysis program (SIRHEN; pronounced 'siren') that has been developed for efficient and robust analysis of PDV data. The program was designed for easy use within Sandia's dynamic compression community.

  11. Basic program "IPFLTR" for induced polarization data reduction and filtering

    USGS Publications Warehouse

    Sadek, Hamdy S.

    1983-01-01

    In the 'IPFLTR' program, the application of the three types of IP filters to the IP pseudosection data was programmed in BASIC. The program allows the user to reduce IP field data and to produce IP pseudosections. It includes three filter subprograms, which calculate output data from each filter. The filtered data include a single reading for each station along the pseudosection. These data can be presented as individual IP profiles, or several profiles can be contoured together to produce an IP map. The program can optionally provide simple or complex plots either of the filtered data or of any selected level in the pseudosection.

  12. Persistent hiccups due to aripiprazole in an adolescent with obsessive compulsive disorder responding to dose reduction and rechallenge

    PubMed Central

    Kutuk, Meryem Ozlem; Tufan, Ali Evren; Guler, Gulen; Yildirim, Veli; Toros, Fevziye

    2016-01-01

    Our case involves persistent hiccup arising in an adolescent with obsessive compulsive disorder (OCD) who was using aripiprazole as an augmentation to fluoxetine and whose hiccups remitted with dose reduction and rechallenge. Treatment suggested that aripiprazole might lead to hiccups. Antipsychotics are also used for the treatment of hiccups, but recent case reports suggest that they cause hiccups as well. Within 12 h of taking 5 mg aripiprazole, the 13-year-old girl began having continuous hiccups, which lasted for 3–4 h. The hiccups resolved when the dose of aripiprazole was reduced to 2.5 mg. To achieve augmentation, aripiprazole was replaced with risperidone 0.5 mg/day for 1 month, but excess sedation was observed. As a result, aripiprazole was restarted at a dose of 2.5 mg/day, and 1 week later, it was increased to 5 mg/every other day. No hiccups were observed. PMID:27099770

  13. Persistent hiccups due to aripiprazole in an adolescent with obsessive compulsive disorder responding to dose reduction and rechallenge.

    PubMed

    Kutuk, Meryem Ozlem; Tufan, Ali Evren; Guler, Gulen; Yildirim, Veli; Toros, Fevziye

    2016-04-01

    Our case involves persistent hiccup arising in an adolescent with obsessive compulsive disorder (OCD) who was using aripiprazole as an augmentation to fluoxetine and whose hiccups remitted with dose reduction and rechallenge. Treatment suggested that aripiprazole might lead to hiccups. Antipsychotics are also used for the treatment of hiccups, but recent case reports suggest that they cause hiccups as well. Within 12 h of taking 5 mg aripiprazole, the 13-year-old girl began having continuous hiccups, which lasted for 3-4 h. The hiccups resolved when the dose of aripiprazole was reduced to 2.5 mg. To achieve augmentation, aripiprazole was replaced with risperidone 0.5 mg/day for 1 month, but excess sedation was observed. As a result, aripiprazole was restarted at a dose of 2.5 mg/day, and 1 week later, it was increased to 5 mg/every other day. No hiccups were observed. PMID:27099770

  14. Rapid Automated Treatment Planning Process to Select Breast Cancer Patients for Active Breathing Control to Achieve Cardiac Dose Reduction

    SciTech Connect

    Wang Wei; Purdie, Thomas G.; Rahman, Mohammad; Marshall, Andrea; Liu Feifei; Fyles, Anthony

    2012-01-01

    Purpose: To evaluate a rapid automated treatment planning process for the selection of patients with left-sided breast cancer for a moderate deep inspiration breath-hold (mDIBH) technique using active breathing control (ABC); and to determine the dose reduction to the left anterior descending coronary artery (LAD) and the heart using mDIBH. Method and Materials: Treatment plans were generated using an automated method for patients undergoing left-sided breast radiotherapy (n = 53) with two-field tangential intensity-modulated radiotherapy. All patients with unfavorable cardiac anatomy, defined as having >10 cm{sup 3} of the heart receiving 50% of the prescribed dose (V{sub 50}) on the free-breathing automated treatment plan, underwent repeat scanning on a protocol using a mDIBH technique and ABC. The doses to the LAD and heart were compared between the free-breathing and mDIBH plans. Results: The automated planning process required approximately 9 min to generate a breast intensity-modulated radiotherapy plan. Using the dose-volume criteria, 20 of the 53 patients were selected for ABC. Significant differences were found between the free-breathing and mDIBH plans for the heart V{sub 50} (29.9 vs. 3.7 cm{sup 3}), mean heart dose (317 vs. 132 cGy), mean LAD dose (2,047 vs. 594 cGy), and maximal dose to 0.2 cm{sup 3} of the LAD (4,155 vs. 1,507 cGy, all p <.001). Of the 17 patients who had a breath-hold threshold of {>=}0.8 L, 14 achieved a {>=}90% reduction in the heart V{sub 50} using the mDIBH technique. The 3 patients who had had a breath-hold threshold <0.8 L achieved a lower, but still significant, reduction in the heart V{sub 50}. Conclusions: A rapid automated treatment planning process can be used to select patients who will benefit most from mDIBH. For selected patients with unfavorable cardiac anatomy, the mDIBH technique using ABC can significantly reduce the dose to the LAD and heart, potentially reducing the cardiac risks.

  15. Dose reduction in orthodontic lateral cephalography: dosimetric evaluation of a novel cephalographic thyroid protector (CTP) and anatomical cranial collimation (ACC)

    PubMed Central

    Rottke, D; van der Stelt, P F; Berkhout, W E R

    2015-01-01

    Objectives: To test the dose-reducing capabilities of a novel thyroid protection device and a recently introduced cranial collimator to be used in orthodontic lateral cephalography. Methods: Cephalographic thyroid protector (CTP) was designed to shield the thyroid while leaving the cervical vertebrae depicted. Using a RANDO® head phantom (The Phantom Laboratory, Salem, NY) equipped with dosemeters and a Proline XC (Planmeca, Helsinki, Finland) cephalograph, lateral cephalograms were taken, and the effective dose (ED) was calculated for four protocols: (1) without shielding; (2) with CTP; (3) with CTP and anatomical cranial collimator (ACC); and (4) with a thyroid collar (TC). Results: The ED for the respective protocols was (1) 8.51; (2) 5.39; (3) 3.50; and (4) 4.97 µSv. The organ dose for the thyroid was reduced from 30.17 to 4.50 µSv in Protocols 2 and 3 and to 3.33 µSv in Protocol 4. Conclusions: The use of just the CTP (Protocol 2) resulted in a 36.8% reduction of the ED of a lateral cephalogram. This was comparable to the classical TC (Protocol 4). A 58.8% reduction of the ED was obtained when combining CTP and ACC (Protocol 3). The dose to the radiosensitive thyroid gland was reduced by 85% in Protocols 2 and 3 and by 89% in Protocol 4. PMID:25564885

  16. Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan

    NASA Astrophysics Data System (ADS)

    Ota, Takamasa; Tsuyuki, Masaharu; Okumura, Miwa; Sano, Tomonari; Kondo, Takeshi; Takase, Shinichi

    2008-03-01

    A novel low-dose ECG-gated helical scan method to investigate coronary artery diseases was developed. This method uses a high pitch for scanning (based on the patient's heart rate) and X-rays are generated only during the optimal cardiac phases. The dose reduction was obtained using a two-level approach: 1) To use a 64-slice CT scanner (Aquilion, Toshiba, Otawara, Tochigi, Japan) with a scan speed of 0.35 s/rot. to helically scan the heart at a high pitch based on the patient's heart rate. By changing the pitch from the conventional 0.175 to 0.271 for a heart rate of 60 bpm, the exposure dose was reduced to 65%. 2) To employ tube current gating that predicts the timing of optimal cardiac phases from the previous cardiac cycle and generates X-rays only during the required cardiac phases. The combination of high speed scanning with a high pitch and appropriate X-ray generation only in the cardiac phases from 60% to 90% allows the exposure dose to be reduced to 5.6 mSv for patients with a heart rate lower than 65 bpm. This is a dose reduction of approximately 70% compared to the conventional scanning method recommended by the manufacturer when segmental reconstruction is considered. This low-dose protocol seamlessly allows for wide scan ranges (e.g., aortic dissection) with the benefits of ECG-gated helical scanning: smooth continuity for longitudinal direction and utilization of data from all cardiac cycles.

  17. 48 CFR 52.223-10 - Waste Reduction Program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... other than fuel for producing heat or power by combustion. Waste prevention means any change in the... implementing regulations (40 CFR part 247). (End of clause) ... 48 Federal Acquisition Regulations System 2 2013-10-01 2013-10-01 false Waste Reduction...

  18. 48 CFR 52.223-10 - Waste Reduction Program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... other than fuel for producing heat or power by combustion. Waste prevention means any change in the... implementing regulations (40 CFR part 247). (End of clause) ... 48 Federal Acquisition Regulations System 2 2014-10-01 2014-10-01 false Waste Reduction...

  19. 48 CFR 52.223-10 - Waste Reduction Program.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... other than fuel for producing heat or power by combustion. Waste prevention means any change in the... implementing regulations (40 CFR part 247). (End of clause) ... 48 Federal Acquisition Regulations System 2 2012-10-01 2012-10-01 false Waste Reduction...

  20. Prejudice Reduction in University Programs for Older Adults

    ERIC Educational Resources Information Center

    Castillo, Jose-Luis Alvarez; Camara, Carmen Palmero; Eguizabal, Alfredo Jimenez

    2011-01-01

    The present paper, drawing from the perspective of social cognition, examines and evaluates an intervention based on social-cognitive perspective-taking on the reduction of stereotyping and prejudice in older adults. Data were collected in a sample of Spanish participants with a mean age of 63.2 years. The intervention, aimed at reducing prejudice…

  1. Revolutionary Concepts for Helicopter Noise Reduction: SILENT Program

    NASA Technical Reports Server (NTRS)

    Edwards, Bryan; Cox, Charles; Booth, Earl R., Jr. (Technical Monitor)

    2002-01-01

    As part of a NASA initiative to reduce helicopter main rotor noise, a Phase 1 study has been performed of candidate noise reduction concepts. Both conventional and novel design technologies have been analyzed that reduce the community impact of helicopter operations. In this study the noise reduction potential and design implications are assessed for conventional means of noise reduction, e.g., tip speed reduction, tip shapes and airfoil tailoring, and for two innovative design concepts: modulated blade spacing and x-force control. Main rotor designs that incorporate modulated blade spacing are shown to have reduced peak noise levels in most flight operations. X-force control alters the helicopter's force balance whereby the miss distance between main rotor blades and shed vortices can be controlled. This control provides a high potential to mitigate BVI noise radiation. Each concept is evaluated using best practice design and analysis methods, achieving the study's aim to significantly reduce noise with minimal performance degradation and no vibration increase. It is concluded that a SILENT main rotor design, incorporating the modulated blade spacing concept, offers significantly reduced noise levels and the potential of a breakthrough in how a helicopter's sound is perceived and judged. The SILENT rotor represents a definite advancement in the state-of-the-art and is selected as the design concept for demonstration in Phase 2. A Phase 2 Implementation Plan is developed for whirl cage and wind tunnel evaluations of a scaled model SILENT rotor.

  2. Caterpillar MorElectric DOE Idle Reduction Demonstration Program

    SciTech Connect

    John Bernardi

    2007-09-30

    This project titled 'Demonstration of the New MorElectric{trademark} Technology as an Idle Reduction Solution' is one of four demonstration projects awarded by the US Department of Energy in 2002. The goal of these demonstration and evaluation projects was to gather objective in-use information on the performance of available idle reduction technologies by characterizing the cost; fuel, maintenance, and engine life savings; payback; and user impressions of various systems and techniques. In brief, the Caterpillar Inc. project involved applying electrically driven accessories for cab comfort during engine-off stops and for reducing fuel consumption during on-highway operation. Caterpillar had equipped and operated five new trucks with the technology in conjunction with International Truck and Engine Corporation and COX Transfer. The most significant result of the project was a demonstrated average idle reduction of 13.8% for the 5 truck MEI fleet over the control fleet. It should be noted that the control fleet trucks were also equipped with an idle reduction device that would start and stop the main engine automatically in order to maintain cab temperature. The control fleet idle usage would have been reduced by 3858 hours over the 2 year period with the MEI system installed, or approximately 2315 gallons of fuel less (calculations assume a fuel consumption of 0.6 gallons per hour for the 13 liter engine at idle). The fuel saved will be significantly larger for higher displacement engines without idle reduction equipment such as the engine auto start/stop device used by COX Transfer. It is common for engines to consume 1.0 gallons per hour which would increase the fuel savings to approximately 1260 gallons per truck per year of typical idling (1800 hours idle/yr).

  3. Reduction of external dose in a wet-contaminated housing area in the Bryansk Region, Russia.

    PubMed

    Roed, J; Andersson, K G; Barkovsky, A N; Fogh, C L; Mishine, A S; Ponamarjov, A V; Ramzaev, V P

    2006-01-01

    An investigation of the feasibility of reducing the external dose rate in a recreational housing area located between the settlements of Guta and Muravinka, Bryansk Region, Russia, which had been contaminated by the Chernobyl accident more than a decade earlier was made. Removal of contaminated topsoil was carried out over an area of about 2000 m2, optimising the thickness of the removed layer according to an assessment of the vertical contaminant distribution. A layer of clean sand was applied to shield against radiation from residual contamination in the ground. Careful monitoring of dose rates in reference positions showed that this could reduce the dose rate outdoors by about a factor of 6. The replacement of a roof was found to reduce the dose rate considerably inside the house. A cost analysis of the operation is presented. PMID:16083997

  4. Radiation Dose Reduction in Dual-Energy CT: Does It Affect the Accuracy of Urinary Stone Characterization?

    PubMed Central

    Qu, Mingliang; Yu, Lifeng; Cardona, Daniel Gomez; Liu, Yu; Duan, Xinhui; Ai, Songtao; Leng, Shuai; Shiung, Maria; McCollough, Cynthia H.

    2016-01-01

    OBJECTIVE The purpose of this article is to assess the effect of radiation dose reduction in dual-energy CT (DECT) on the performance of renal stone characterization using a patient cohort. MATERIALS AND METHODS CT data from 39 unenhanced DECT examinations performed for stone characterization were retrospectively analyzed in this study. Reduced-dose images were simulated at 75%, 50%, and 25% of the routine dose using a previously validated noise-insertion algorithm. Differentiation between uric acid (UA) and non-UA stones was performed using a fixed cutoff value for the dual-energy ratio. ROC analysis was performed to determine optimal cutoff values and the associated sensitivity and specificity. RESULTS Of the 206 stones found, 43 were UA and 163 were non-UA. The mean (± SD) volume CT dose index (CTDIvol) was 16.0 ± 4.0 mGy at the 100% dose level. The mean noise in 100-kV images increased from 40.9 ± 6.8 HU at 100% dose to 46.8 ± 8.8 HU, 57.7 ± 12.5 HU, and 85.4 ± 22.9 HU at 75%, 50%, and 25% dose levels, respectively. Using the default cutoff value, for stones 10 mm3 or larger, the sensitivity/specificity were 100.0%/98.8%, 82.8%/98.8%, and 89.3%/98.7%, at 75%, 50%, and 25% dose levels, respectively. ROC analysis showed varying optimal cutoff values at different dose levels. The sensitivity and specificity improved with use of these optimal cutoff values. Differentiation capability decreased for stones smaller than 10 mm3. CONCLUSION At 75% of the 16-mGy routine dose, the sensitivity and specificity for differentiating UA from non-UA stones were minimally affected for stones 10 mm3 or larger. The use of optimal cutoff values for dual-energy ratio as dose decreased (and noise increased) provided improved performance. PMID:26204304

  5. 77 FR 68106 - Second Fishing Capacity Reduction Program for the Longline Catcher Processor Subsector of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ... permit. NMFS published proposed program regulations on July 30, 2012 (77 FR 44572), and final program regulations on September 24, 2012 (77 FR 58775), to implement the second reduction program. Interested persons... for the Longline Catcher Processor Subsector of the Bering Sea and Aleutian Islands Non-...

  6. Combining Primary Prevention and Risk Reduction Approaches in Sexual Assault Protection Programming

    ERIC Educational Resources Information Center

    Menning, Chadwick; Holtzman, Mellisa

    2015-01-01

    Objective: The object of this study is to extend prior evaluations of Elemental, a sexual assault protection program that combines primary prevention and risk reduction strategies within a single program. Participants and Methods: During 2012 and 2013, program group and control group students completed pretest, posttest, and 6-week and 6-month…

  7. 78 FR 33810 - Fishing Capacity Reduction Program for the Southeast Alaska Purse Seine Salmon Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... proposed program regulations on May 23, 2011 (76 FR 29707), and final program regulations on October 6, 2011 (76 FR 61985), to implement the reduction program. Subsequently, the Southeast Revitalization... published the list of eligible voters on March 1, 2012 (77 FR 12568) and the notice of referendum period...

  8. 77 FR 41754 - Fishing Capacity Reduction Program for the Southeast Alaska Purse Seine Salmon Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-16

    ...). NMFS published proposed program regulations on May 23, 2011 (76 FR 29707), and final program regulations on October 6, 2011 (76 FR 61985), to implement the reduction program. Subsequently, the Southeast..., 2012. NMFS published the list of eligible voters on March 1, 2012 (77 FR 12568) and the notice...

  9. 77 FR 12568 - Fishing Capacity Reduction Program for the Southeast Alaska Purse Seine Salmon Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ...). NMFS published proposed program regulations on May 23, 2011 (76 FR 29707), and final program regulations on October 6, 2011 (76 FR 61986), to implement the reduction program. Interested persons should... 7602 76TH AVE SW.... LAKEWOOD WA 98498 95 MARBLE DALE H....... 59248 478 DE HARO LN...... FRIDAY...

  10. Ultra-low-dose dual-source CT coronary angiography with high pitch: diagnostic yield of a volumetric planning scan and effects on dose reduction and imaging strategy

    PubMed Central

    Hamm, B; Huppertz, A; Lembcke, A

    2015-01-01

    Objective: To evaluate the role of an ultra-low-dose dual-source CT coronary angiography (CTCA) scan with high pitch for delimiting the range of the subsequent standard CTCA scan. Methods: 30 patients with an indication for CTCA were prospectively examined using a two-scan dual-source CTCA protocol (2.0 × 64.0 × 0.6 mm; pitch, 3.4; rotation time of 280 ms; 100 kV): Scan 1 was acquired with one-fifth of the tube current suggested by the automatic exposure control software [CareDose 4D™ (Siemens Healthcare, Erlangen, Germany) using 100 kV and 370 mAs as a reference] with the scan length from the tracheal bifurcation to the diaphragmatic border. Scan 2 was acquired with standard tube current extending with reduced scan length based on Scan 1. Nine central coronary artery segments were analysed qualitatively on both scans. Results: Scan 2 (105.1 ± 10.1 mm) was significantly shorter than Scan 1 (127.0 ± 8.7 mm). Image quality scores were significantly better for Scan 2. However, in 5 of 6 (83%) patients with stenotic coronary artery disease, a stenosis was already detected in Scan 1 and in 13 of 24 (54%) patients with non-stenotic coronary arteries, a stenosis was already excluded by Scan 1. Using Scan 2 as reference, the positive- and negative-predictive value of Scan 1 was 83% (5 of 6 patients) and 100% (13 of 13 patients), respectively. Conclusion: An ultra-low-dose CTCA planning scan enables a reliable scan length reduction of the following standard CTCA scan and allows for correct diagnosis in a substantial proportion of patients. Advances in knowledge: Further dose reductions are possible owing to a change in the individual patient's imaging strategy as a prior ultra-low-dose CTCA scan may already rule out the presence of a stenosis or may lead to a direct transferal to an invasive catheter procedure. PMID:25710210

  11. Prescription co-pay reduction program for diabetic employees.

    PubMed

    Nair, Kavita V; Miller, Kerri; Park, Jinhee; Allen, Richard R; Saseen, Joseph J; Biddle, Vinita

    2010-10-01

    The objective of this study was to examine the impact of reducing the prescription co-pay for diabetes medications on pharmacy utilization, medication adherence, medical utilization, and expenditures. The co-pay reduction involved placing all diabetic drugs and testing supplies on the lowest co-pay tier for one employer group. The sample comprised members with diabetes who were both continuously enrolled in the 12-month pre period and the 2 years following co-pay reduction. Measured outcomes included diabetic prescription utilization, medication adherence, medical utilization, and expenditures. Generalized estimating equations for repeated measures were used to estimate differences between the pre period and years 1 and 2, while adjusting for age, sex, and comorbidity risk. Diabetic prescription utilization and medication adherence increased by approximately 3.0% in year 1 and dropped in year 2. The increases were primarily in brand name diabetes medications, which increased by approximately 5%, while generic use decreased in both years. Decreases in emergency room visits and hospitalizations were also observed in both years, followed by a decrease in health care expenditures in year 2. Adherent members experienced greater decreases in emergency room visits following the co-pay reduction compared to nonadherent members. After the implementation of a co-pay reduction, a modest increase in adherence and use of diabetes medications was observed. There were some compensatory cost savings for the employer from lower medical expenditures in year 1. In addition to financial strategies, additional strategies to reinforce medication adherence are needed to gain and sustain more meaningful increases in prescription utilization. PMID:20879904

  12. Omega flight-test data reduction sequence. [computer programs for reduction of navigation data

    NASA Technical Reports Server (NTRS)

    Lilley, R. W.

    1974-01-01

    Computer programs for Omega data conversion, summary, and preparation for distribution are presented. Program logic and sample data formats are included, along with operational instructions for each program. Flight data (or data collected in flight format in the laboratory) is provided by the Ohio University Omega receiver base in the form of 6-bit binary words representing the phase of an Omega station with respect to the receiver's local clock. All eight Omega stations are measured in each 10-second Omega time frame. In addition, an event-marker bit and a time-slot D synchronizing bit are recorded. Program FDCON is used to remove data from the flight recorder tape and place it on data-processing cards for later use. Program FDSUM provides for computer plotting of selected LOP's, for single-station phase plots, and for printout of basic signal statistics for each Omega channel. Mean phase and standard deviation are printed, along with data from which a phase distribution can be plotted for each Omega station. Program DACOP simply copies the Omega data deck a controlled number of times, for distribution to users.

  13. Reduction of Dose Delivered to Organs at Risk in Prostate Cancer Patients via Image-Guided Radiation Therapy

    SciTech Connect

    Pawlowski, Jason M.; Yang, Eddy S.; Malcolm, Arnold W.; Coffey, Charles W.; Ding, George X.

    2010-03-01

    Purpose: To determine whether image guidance can improve the dose delivered to target organs and organs at risk (OARs) for prostate cancer patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Eight prostate cancer patients were treated with IMRT to 76 Gy at 2 Gy per fraction. Daily target localization was performed via alignment of three intraprostatic fiducials and weekly kV-cone beam computed tomography (CBCT) scans. The prostate and OARs were manually contoured on each CBCT by a single physician. Daily patient setup shifts were obtained by comparing alignment of skin tattoos with the treatment position based on fiducials. Treatment fields were retrospectively applied to CBCT scans. The dose distributions were calculated using actual treatment plans (an 8-mm PTV margin everywhere except for 6-mm posteriorly) with and without image guidance shifts. Furthermore, the feasibility of margin reduction was evaluated by reducing planning margins to 4 mm everywhere except for 3 mm posteriorly. Results: For the eight treatment plans on the 56 CBCT scans, the average doses to 98% of the prostate (D98) were 102% (range, 99-104%) and 99% (range, 45-104%) with and without image guidance, respectively. Using margin reduction, the average D98s were 100% (range, 84-104%) and 92% (range, 40-104%) with and without image guidance, respectively. Conclusions: Currently, margins used in IMRT plans are adequate to deliver a dose to the prostate with conventional patient positioning using skin tattoos or bony anatomy. The use of image guidance may facilitate significant reduction of planning margins. Future studies to assess the efficacy of decreasing margins and improvement of treatment-related toxicities are warranted.

  14. Cannabidiol reverses the reduction in social interaction produced by low dose Delta(9)-tetrahydrocannabinol in rats.

    PubMed

    Malone, Daniel Thomas; Jongejan, Dennis; Taylor, David Alan

    2009-08-01

    While Delta(9)-tetrahydrocannabinol (THC) is the main psychoactive constituent of the cannabis plant, a non-psychoactive constituent is cannabidiol (CBD). CBD has been implicated as a potential treatment of a number of disorders including schizophrenia and epilepsy and has been included with THC in a 1:1 combination for the treatment of conditions such as neuropathic pain. This study investigated the effect of THC and CBD, alone or in combination, on some objective behaviours of rats in the open field. Pairs of rats were injected with CBD or vehicle followed by THC or vehicle and behaviour in the open field was assessed for 10 min. In vehicle pretreated rats THC (1 mg/kg) significantly reduced social interaction between rat pairs. Treatment with CBD had no significant effect alone, but pretreatment with CBD (20 mg/kg) reversed the THC-induced decreases in social interaction. A higher dose of THC (10 mg/kg) produced no significant effect on social interaction. However, the combination of high dose CBD and high dose THC significantly reduced social interaction between rat pairs, as well as producing a significant decrease in locomotor activity. This data suggests that CBD can reverse social withdrawal induced by low dose THC, but the combination of high dose THC and CBD impairs social interaction, possibly by decreasing locomotor activity. PMID:19393686

  15. Immunosuppressant dose reduction and long-term rejection risk in renal transplant recipients with severe bacterial pneumonia

    PubMed Central

    Shih, Chia-Jen; Tarng, Der-Cherng; Yang, Wu-Chang; Yang, Chih-Yu

    2014-01-01

    INTRODUCTION Due to lifelong immunosuppression, renal transplant recipients (RTRs) are at risk of infectious complications such as pneumonia. Severe pneumonia results in respiratory failure and is life-threatening. We aimed to examine the influence of immunosuppressant dose reduction on RTRs with bacterial pneumonia and respiratory failure. METHODS From January 2001 to January 2011, 33 of 1,146 RTRs at a single centre developed bacterial pneumonia with respiratory failure. All patients were treated using mechanical ventilation and aggressive therapies in the intensive care unit. RESULTS Average time from kidney transplantation to pneumonia with respiratory failure was 6.8 years. In-hospital mortality rate was 45.5% despite intensive care and aggressive therapies. Logistic regression analysis indicated that a high serum creatinine level at the time of admission to the intensive care unit (odds ratio 1.77 per mg/dL, 95% confidence interval 1.01–3.09; p = 0.045) was a mortality determinant. Out of the 33 patients, immunosuppressive agents were reduced in 17 (51.5%). We found that although immunosuppressant dose reduction tended to improve in-hospital mortality, this was not statistically significant. Nevertheless, during a mean follow-up period of two years, none of the survivors (n = 18) developed acute rejection or allograft necrosis. CONCLUSION In RTRs with bacterial pneumonia and respiratory failure, higher serum creatinine levels were a mortality determinant. Although temporary immunosuppressant dose reduction might not reduce mortality, it was associated with a minimal risk of acute rejection during the two-year follow-up. Our results suggest that early immunosuppressant reduction in RTRs with severe pneumonia of indeterminate microbiology may be safe even when pathogens are bacterial in nature. PMID:25091886

  16. Assessing image quality and dose reduction of a new x-ray computed tomography iterative reconstruction algorithm using model observers

    SciTech Connect

    Tseng, Hsin-Wu Kupinski, Matthew A.; Fan, Jiahua; Sainath, Paavana; Hsieh, Jiang

    2014-07-15

    Purpose: A number of different techniques have been developed to reduce radiation dose in x-ray computed tomography (CT) imaging. In this paper, the authors will compare task-based measures of image quality of CT images reconstructed by two algorithms: conventional filtered back projection (FBP), and a new iterative reconstruction algorithm (IR). Methods: To assess image quality, the authors used the performance of a channelized Hotelling observer acting on reconstructed image slices. The selected channels are dense difference Gaussian channels (DDOG).A body phantom and a head phantom were imaged 50 times at different dose levels to obtain the data needed to assess image quality. The phantoms consisted of uniform backgrounds with low contrast signals embedded at various locations. The tasks the observer model performed included (1) detection of a signal of known location and shape, and (2) detection and localization of a signal of known shape. The employed DDOG channels are based on the response of the human visual system. Performance was assessed using the areas under ROC curves and areas under localization ROC curves. Results: For signal known exactly (SKE) and location unknown/signal shape known tasks with circular signals of different sizes and contrasts, the authors’ task-based measures showed that a FBP equivalent image quality can be achieved at lower dose levels using the IR algorithm. For the SKE case, the range of dose reduction is 50%–67% (head phantom) and 68%–82% (body phantom). For the study of location unknown/signal shape known, the dose reduction range can be reached at 67%–75% for head phantom and 67%–77% for body phantom case. These results suggest that the IR images at lower dose settings can reach the same image quality when compared to full dose conventional FBP images. Conclusions: The work presented provides an objective way to quantitatively assess the image quality of a newly introduced CT IR algorithm. The performance of the

  17. Overview of the U. S. Environmental Protection Agency's Hazardous Air Pollutant Early Reduction Program

    SciTech Connect

    Laznow, J. ); Daniel, J. )

    1992-01-01

    Under provision of the Clean Air Act Amendments of 1990 Title III, the EPA has proposed a regulation (Early Reduction Program) to allow a six-year compliance extension from Maximum Achievable Control Technology (MACT) standards for sources that voluntarily reduce emissions of Hazardous Air Pollutants (HAPs) by 90% or more (95% or more for particulates) from a base year of 1987 or later. The emission reduction must be made before the applicable MACT standard is proposed for the source category or be subject to an enforceable commitment to achieve the reduction by January 1, 1994 for sources subject to MACT standards prior to 1994. The primary purpose of this program is to encourage reduction of HAPs emissions sooner than otherwise required. Industry would be allowed additional time in evaluating emission reduction options and developing more cost-effective compliance strategies, although, under strict guidelines to ensure actual, significant and verifiable emission reductions occur.

  18. SENSIT.FOR: A program for sensitometric reduction

    NASA Astrophysics Data System (ADS)

    Maury, A.; Marchal, J.

    1984-09-01

    A FORTRAN program for sensitometric evaluation of processes involved in hypering astronomical plates was written. It contains subroutines for full or quick description of the operation being done; choice of type of sensitogram; creation of 16 subfiles in the scan; density filtering; correction for area; specular PDS to diffuse ISO density calibration; and fog correction.

  19. Perceived Risk and Risk Reduction Strategies in Study Abroad Programs

    ERIC Educational Resources Information Center

    Luethge, Denise J.

    2004-01-01

    The study abroad program (SAP) meets the criteria of a risky purchase, namely of being non-tangible, possessing hidden qualities, being expensive and cannot being able to be tested prior to purchase. In fact, SAPs may score highly on a number of risk components, especially financial risk (expensive), psychological risk (anxiety), physical risk…

  20. Computer program for absorbed dose to the breast in mammography. Final report

    SciTech Connect

    Andersen, L.W.; Rosenstein, M.

    1985-07-01

    Two computer programs are used to generate absorbed dose to tissues in the breast from mammographic procedures. The first program calculates the absorbed dose to total breast tissue and glandular tissue for five reference breast sizes and several compositions, for a number of mammographic x-ray spectra. A data file is generated containing these data. The second program uses the data file generated by the first program, and produces for each reference breast and breast composition a mathematical curve fit as a function of beam quality (HVL, mm Al), using a polynomial expansion. Data tables are then produced by interpolation at discrete values of beam quality. The programs are in FORTRAN IV and run on an IBM 370/168 system using Multiple Virtual Storage. All input/output files are sequential.

  1. 77 FR 44572 - Second Fishing Capacity Reduction Program for the Longline Catcher Processor Subsector of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-30

    ... National Oceanic and Atmospheric Administration 50 CFR Part 600 RIN 0648-BB06 Second Fishing Capacity... proposes regulations to implement a second fishing capacity reduction program (also commonly known as... that particular buyback. To undertake this second round of capacity reduction for the BSAI...

  2. Dose reduction in digital breast tomosynthesis using a penalized maximum likelihood reconstruction

    NASA Astrophysics Data System (ADS)

    Das, Mini; Gifford, Howard; O'Connor, Michael; Glick, Stephen J.

    2009-02-01

    Digital breast tomosynthesis (DBT) is a 3D imaging modality with limited angle projection data. The ability of tomosynthesis systems to accurately detect smaller microcalcifications is debatable. This is because of the higher noise in the projection data (lower average dose per projection), which is then propagated through the reconstructed image . Reconstruction methods that minimize the propagation of quantum noise have potential to improve microcalcification detectability using DBT. In this paper we show that penalized maximum likelihood (PML) reconstruction in DBT yields images with an improved resolution/noise tradeoff as compared to conventional filtered backprojection (FBP). Signal to noise ratio (SNR) using PML was observed to be higher than that obtained using the standard FBP algorithm. Our results indicate that for microcalcifications, using the PML algorithm, reconstructions obtained with a mean glandular dose (MGD) of 1.5 mGy yielded better SNR than that those obtained with FBP using a 4mGy total dose. Thus perhaps total dose could be reduced to one-third or lower with same microcalcification detectability, if PML reconstruction is used instead of FBP. Visibility of low contrast masses with various contrast levels were studied using a contrast-detail phantom in a breast shape structure with an average breast density. Images generated using various dose levels indicate that visibility of low contrast masses generated using PML reconstructions are significantly better than those generated using FBP. SNR measurements in the low-contrast study did not appear to correlate with the visual subjective analysis of the reconstruction indicating that SNR is not a good figure of merit to be used.

  3. Reduction of the radiation dose for intracranial germinoma: a prospective study.

    PubMed Central

    Shibamoto, Y.; Takahashi, M.; Abe, M.

    1994-01-01

    Intracranial germinoma has usually been treated with radiation doses of 50 Gy or more, but it is unclear whether such doses are actually necessary to cure this radiosensitive tumour. At our institution, the standard radiation dose for intracranial germinoma was 60 Gy in the 1960s, but the dose has prospectively been reduced stepwise to 40-45 Gy. In this paper, the treatment outcome was assessed in 84 patients (47 with histologically confirmed disease and 37 diagnosed clinically in the post-computerised tomography era) enrolled in both prospective and retrospective series. The 5 and 10 years survival rates for all 84 patients were 88% and 83% respectively, and the corresponding relapse-free survival rates were 88% and 85%. The 10-year relapse-free survival rate was 88% for 31 patients receiving 19-47 Gy (median 42 Gy) to the primary tumour, 92% for 28 patients receiving 48-52 Gy (median 50 Gy), and 83% for 25 patients receiving 54-62 Gy (median 60 Gy), and there was no significant difference among the three groups. In-field local recurrence only developed in one patient who received 40 Gy over a protracted period and one patient who received 60 Gy. A tumour size < 3 cm and treatment in the post-computerised tomography era were associated with a better prognosis according to univariate analysis, while age, sex, tumour site, treatment volume, the radiation dose to both the primary and the spinal cord and the extent of surgical resection did not influence the prognosis. In contrast, none of these factors had a significant influence in multivariate analysis. In conclusion, intracranial germinomas < or = 4 cm in size can usually be cured with 40-45 Gy of radiation, thus avoiding the major adverse effects of brain irradiation. PMID:7947108

  4. Propulsion. [NASA program for aircraft fuel consumption reduction

    NASA Technical Reports Server (NTRS)

    Nored, D. L.

    1978-01-01

    NASA aims at developing propulsion technology to reduce the fuel consumption of present engines by 5%, that of new engines of the late 1980s by at least 12%, and that of an advanced early 1990s turboprop by an additional 15%. This paper reviews three separate NASA programs which take up these aims. They are, respectively, Engine Component Improvement, Energy Efficient Engine, and Advanced Turboprops.

  5. Hearing screening program impact on noise reduction strategies.

    PubMed

    Voaklander, D C; Franklin, R C; Challinor, K; Depczynski, J; Fragar, L J

    2009-04-01

    The objective of this study was to determine the impact of the New South Wales Rural Hearing Conservation Program on the implementation of personal hearing protection (PHP) and noise management strategies among farmers who had participated in this program in New South Wales, Australia. A follow-up survey of a random sample of people screened through the New South Wales Rural Hearing Conservation Program was linked to their baseline data. The use of PHP at baseline was compared to use at follow-up in four specific scenarios: use with non-cabbed tractors, with chainsaws, with firearms, and in workshops. For non-cabbed tractors, the net gain in PHP use was 13.3%; the net gain was 20.8% for chainsaws, 6.7% for firearms, and 21.3% for workshops. Older farmers and those with a family history of hearing loss were less likely to maintain or improve PHP use. Those with severe hearing loss, males, and participants reporting hearing problems in situations where background noise was present were more likely to maintain or improve PHP use. Forty-one percent of farmers had initiated other strategies to reduce noise exposure beyond the use of PHP, which included engineering, maintenance, and noise avoidance solutions. The early (hopefully) identification of hearing deficit in farmers and farm workers can help promote behavior change and help reinforce a farm culture that supports hearing conservation. The continuation and expansion of hearing screening programs such as these should be encouraged as basic public health strategy in farming communities. PMID:19496341

  6. Programs for Data Reduction and Optimization of the System Work

    NASA Astrophysics Data System (ADS)

    Breus, V. V.

    During last years, some new computer programs were developed. In this article, will be described three of them. The "Variable Stars Calculator" was developed for processing photometrical observations of variable stars. It helps the observer at each step from converting estimates of brightness into stellar magnitudes to searching a period of changing brightness, PCA analysis, searching extremums by the polynomial approximation etc. The program has Ukrainian, Russian an English interface languages and it is possible to add new ones. The "PolarObs" was developed for processing polarimetrical observations, obtained at the 2.6 Shain telescope in the Crimean astrophysical observatory. It was used either for processing observations of cataclysmic variable stars, or for comets. "TrayDog" is a system tool for Windows with more than 50 functions. Enhanced Task manager, that can view and edit properties of process, windows, libraries, threads, network ports and opened files. Other functions are: switching between desktops by hot-key, minimize any window to the system tray area, system information, blocking pop-ups of any kind, view and connect network shared resources, alarm clock andother functions. The interface of the current version is only in Russian. These and some other programs can be downloaded from the pages http://uavso.org.ua/breus, http://uavso.org.ua/breus

  7. Augmentor emissions reduction technology program. [for turbofan engines

    NASA Technical Reports Server (NTRS)

    Colley, W. C.; Kenworthy, M. J.; Bahr, D. W.

    1977-01-01

    Technology to reduce pollutant emissions from duct-burner-type augmentors for use on advanced supersonic cruise aircraft was investigated. Test configurations, representing variations of two duct-burner design concepts, were tested in a rectangular sector rig at inlet temperature and pressure conditions corresponding to takeoff, transonic climb, and supersonic cruise flight conditions. Both design concepts used piloted flameholders to stabilize combustion of lean, premixed fuel/air mixtures. The concepts differed in the flameholder type used. High combustion efficiency (97%) and low levels of emissions (1.19 g/kg fuel) were achieved. The detailed measurements suggested the direction that future development efforts should take to obtain further reductions in emission levels and associated improvements in combustion efficiency over an increased range of temperature rise conditions.

  8. Reduction of eye lens radiation dose by orbital bismuth shielding in pediatric patients undergoing CT of the head: a Monte Carlo study.

    PubMed

    Perisinakis, Kostas; Raissaki, Maria; Theocharopoulos, Nicholas; Damilakis, John; Gourtsoyiannis, Nicholas

    2005-04-01

    Our aim in the study was to assess the eye lens dose reduction resulting from the use of radioprotective bismuth garments to shield the eyes of pediatric patients undergoing head CT. The Monte Carlo N-particle transport code and mathematical humanoid phantoms representing the average individual at different ages were used to determine eye lens dose reduction accomplished with bismuth shielding of the eye in the following simulated CT scans: (a) scanning of the orbits, (b) scanning of the whole head, and (c) 20 degrees angled scanning of the brain excluding the orbits. The effect of bismuth shielding on the eye lens dose was also investigated using an anthropomorphic phantom and thermoluminescence dosimetry (TLD). Eye lens dose reduction achieved by bismuth shielding was measured in 16 patients undergoing multiphase CT scanning of the head. The patient's scans were divided in the following: CT examinations where the eye globes were entirely included (n=5), partly included (n=6) and excluded (n=5) from the scanned region. The eye lens dose reduction depended mainly on the scan boundaries set by an operator. The average eye lens dose reduction determined by Monte Carlo simulation was 38.2%, 33.0% and <1% for CT scans of the orbits, whole head, and brain with an angled gantry, respectively. The difference between the Monte Carlo derived eye lens dose reduction factor values and corresponding values determined directly by using the anthropomorphic phantom head was found less than 5%. The mean eye lens dose reduction achieved by bismuth shielding in pediatric patients were 34%, 20% and <2% when eye globes were entirely included, partly included and excluded from the scanned region, respectively. A significant reduction in eye lens dose may be achieved by using superficial orbital bismuth shielding during pediatric head CT scans. However, bismuth garments should not be used in children when the eyes are excluded from the primarily exposed region. PMID:15895586

  9. Reduction of eye lens radiation dose by orbital bismuth shielding in pediatric patients undergoing CT of the head: A Monte Carlo study

    SciTech Connect

    Perisinakis, Kostas; Raissaki, Maria; Tzedakis, Antonis; Theocharopoulos, Nicholas; Damilakis, John; Gourtsoyiannis, Nicholas

    2005-04-01

    Our aim in the study was to assess the eye lens dose reduction resulting from the use of radioprotective bismuth garments to shield the eyes of pediatric patients undergoing head CT. The Monte Carlo N-particle transport code and mathematical humanoid phantoms representing the average individual at different ages were used to determine eye lens dose reduction accomplished with bismuth shielding of the eye in the following simulated CT scans: (a) scanning of the orbits, (b) scanning of the whole head, and (c) 20 deg. angled scanning of the brain excluding the orbits. The effect of bismuth shielding on the eye lens dose was also investigated using an anthropomorphic phantom and thermoluminescence dosimetry (TLD). Eye lens dose reduction achieved by bismuth shielding was measured in 16 patients undergoing multiphase CT scanning of the head. The patient's scans were divided in the following: CT examinations where the eye globes were entirely included (n=5), partly included (n=6) and excluded (n=5) from the scanned region. The eye lens dose reduction depended mainly on the scan boundaries set by an operator. The average eye lens dose reduction determined by Monte Carlo simulation was 38.2%, 33.0% and <1% for CT scans of the orbits, whole head, and brain with an angled gantry, respectively. The difference between the Monte Carlo derived eye lens dose reduction factor values and corresponding values determined directly by using the anthropomorphic phantom head was found less than 5%. The mean eye lens dose reduction achieved by bismuth shielding in pediatric patients were 34%, 20% and <2% when eye globes were entirely included, partly included and excluded from the scanned region, respectively. A significant reduction in eye lens dose may be achieved by using superficial orbital bismuth shielding during pediatric head CT scans. However, bismuth garments should not be used in children when the eyes are excluded from the primarily exposed region.

  10. Image Quality and Radiation Dose of CT Coronary Angiography with Automatic Tube Current Modulation and Strong Adaptive Iterative Dose Reduction Three-Dimensional (AIDR3D)

    PubMed Central

    Shen, Hesong; Dai, Guochao; Luo, Mingyue; Duan, Chaijie; Cai, Wenli; Liang, Dan; Wang, Xinhua; Zhu, Dongyun; Li, Wenru; Qiu, Jianping

    2015-01-01

    Purpose To investigate image quality and radiation dose of CT coronary angiography (CTCA) scanned using automatic tube current modulation (ATCM) and reconstructed by strong adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Eighty-four consecutive CTCA patients were collected for the study. All patients were scanned using ATCM and reconstructed with strong AIDR3D, standard AIDR3D and filtered back-projection (FBP) respectively. Two radiologists who were blinded to the patients' clinical data and reconstruction methods evaluated image quality. Quantitative image quality evaluation included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). To evaluate image quality qualitatively, coronary artery is classified into 15 segments based on the modified guidelines of the American Heart Association. Qualitative image quality was evaluated using a 4-point scale. Radiation dose was calculated based on dose-length product. Results Compared with standard AIDR3D, strong AIDR3D had lower image noise, higher SNR and CNR, their differences were all statistically significant (P<0.05); compared with FBP, strong AIDR3D decreased image noise by 46.1%, increased SNR by 84.7%, and improved CNR by 82.2%, their differences were all statistically significant (P<0.05 or 0.001). Segments with diagnostic image quality for strong AIDR3D were 336 (100.0%), 486 (96.4%), and 394 (93.8%) in proximal, middle, and distal part respectively; whereas those for standard AIDR3D were 332 (98.8%), 472 (93.7%), 378 (90.0%), respectively; those for FBP were 217 (64.6%), 173 (34.3%), 114 (27.1%), respectively; total segments with diagnostic image quality in strong AIDR3D (1216, 96.5%) were higher than those of standard AIDR3D (1182, 93.8%) and FBP (504, 40.0%); the differences between strong AIDR3D and standard AIDR3D, strong AIDR3D and FBP were all statistically significant (P<0.05 or 0.001). The mean effective radiation dose was (2.55±1.21) mSv. Conclusion

  11. Influence of thyroid volume reduction on absorbed dose in 131I therapy studied by using Geant4 Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Ziaur, Rahman; Sikander, M. Mirza; Waheed, Arshed; Nasir, M. Mirza; Waheed, Ahmed

    2014-05-01

    A simulation study has been performed to quantify the effect of volume reduction on the thyroid absorbed dose per decay and to investigate the variation of energy deposition per decay due to β- and γ-activity of 131I with volume/mass of thyroid, for water, ICRP- and ICRU-soft tissue taken as thyroid material. A Monte Carlo model of the thyroid, in the Geant4 radiation transport simulation toolkit was constructed to compute the β- and γ-absorbed dose in the simulated thyroid phantom for various values of its volume. The effect of the size and shape of the thyroid on energy deposition per decay has also been studied by using spherical, ellipsoidal and cylindrical models for the thyroid and varying its volume in 1-25 cm3 range. The relative differences of Geant4 results for different models with each other and MCNP results lie well below 1.870%. The maximum relative difference among the Geant4 estimated results for water with ICRP and ICRU soft tissues is not more than 0.225%. S-values for ellipsoidal, spherical and cylindrical thyroid models were estimated and the relative difference with published results lies within 3.095%. The absorbed fraction values for beta particles show a good agreement with published values within 2.105% deviation. The Geant4 based simulation results of absorbed fractions for gammas again show a good agreement with the corresponding MCNP and EGS4 results (±6.667%) but have 29.032% higher values than that of MIRD calculated values. Consistent with previous studies, the reduction of the thyroid volume is found to have a substantial effect on the absorbed dose. Geant4 simulations confirm dose dependence on the volume/mass of thyroid in agreement with MCNP and EGS4 computed values but are substantially different from MIRD8 data. Therefore, inclusion of size/mass dependence is indicated for 131I radiotherapy of the thyroid.

  12. Determination of the Optimal Dose Reduction Level via Iterative Reconstruction Using 640-Slice Volume Chest CT in a Pig Model

    PubMed Central

    Liu, Xingli; Wang, Jingshi; Liu, Qin; Zhao, Pengfei; Hou, Yang; Ma, Yue; Guo, Qiyong

    2015-01-01

    Aim To determine the optimal dose reduction level of iterative reconstruction technique for paediatric chest CT in pig models. Materials and Methods 27 infant pigs underwent 640-slice volume chest CT with 80kVp and different mAs. Automatic exposure control technique was used, and the index of noise was set to SD10 (Group A, routine dose), SD12.5, SD15, SD17.5, SD20 (Groups from B to E) to reduce dose respectively. Group A was reconstructed with filtered back projection (FBP), and Groups from B to E were reconstructed using iterative reconstruction (IR). Objective and subjective image quality (IQ) among groups were compared to determine an optimal radiation reduction level. Results The noise and signal-to-noise ratio (SNR) in Group D had no significant statistical difference from that in Group A (P = 1.0). The scores of subjective IQ in Group A were not significantly different from those in Group D (P>0.05). There were no obvious statistical differences in the objective and subjective index values among the subgroups (small, medium and large subgroups) of Group D. The effective dose (ED) of Group D was 58.9% lower than that of Group A (0.20±0.05mSv vs 0.48±0.10mSv, p <0.001). Conclusions In infant pig chest CT, using iterative reconstruction can provide diagnostic image quality; furthermore, it can reduce the dosage by 58.9%. PMID:25764485

  13. Fast patient-specific Monte Carlo brachytherapy dose calculations via the correlated sampling variance reduction technique

    SciTech Connect

    Sampson, Andrew; Le Yi; Williamson, Jeffrey F.

    2012-02-15

    Purpose: To demonstrate potential of correlated sampling Monte Carlo (CMC) simulation to improve the calculation efficiency for permanent seed brachytherapy (PSB) implants without loss of accuracy. Methods: CMC was implemented within an in-house MC code family (PTRAN) and used to compute 3D dose distributions for two patient cases: a clinical PSB postimplant prostate CT imaging study and a simulated post lumpectomy breast PSB implant planned on a screening dedicated breast cone-beam CT patient exam. CMC tallies the dose difference, {Delta}D, between highly correlated histories in homogeneous and heterogeneous geometries. The heterogeneous geometry histories were derived from photon collisions sampled in a geometrically identical but purely homogeneous medium geometry, by altering their particle weights to correct for bias. The prostate case consisted of 78 Model-6711 {sup 125}I seeds. The breast case consisted of 87 Model-200 {sup 103}Pd seeds embedded around a simulated lumpectomy cavity. Systematic and random errors in CMC were unfolded using low-uncertainty uncorrelated MC (UMC) as the benchmark. CMC efficiency gains, relative to UMC, were computed for all voxels, and the mean was classified in regions that received minimum doses greater than 20%, 50%, and 90% of D{sub 90}, as well as for various anatomical regions. Results: Systematic errors in CMC relative to UMC were less than 0.6% for 99% of the voxels and 0.04% for 100% of the voxels for the prostate and breast cases, respectively. For a 1 x 1 x 1 mm{sup 3} dose grid, efficiency gains were realized in all structures with 38.1- and 59.8-fold average gains within the prostate and breast clinical target volumes (CTVs), respectively. Greater than 99% of the voxels within the prostate and breast CTVs experienced an efficiency gain. Additionally, it was shown that efficiency losses were confined to low dose regions while the largest gains were located where little difference exists between the homogeneous and

  14. Radiation Dose Reduction Methods For Use With Fluoroscopic Imaging, Computers And Implications For Image Quality

    NASA Astrophysics Data System (ADS)

    Edmonds, E. W.; Hynes, D. M.; Rowlands, J. A.; Toth, B. D.; Porter, A. J.

    1988-06-01

    The use of a beam splitting device for medical gastro-intestinal fluoroscopy has demonstrated that clinical images obtained with a 100mm photofluorographic camera, and a 1024 X 1024 digital matrix with pulsed progressive readout acquisition techniques, are identical. In addition, it has been found that clinical images can be obtained with digital systems at dose levels lower than those possible with film. The use of pulsed fluoroscopy with intermittent storage of the fluoroscopic image has also been demonstrated to reduce the fluoroscopy part of the examination to very low dose levels, particularly when low repetition rates of about 2 frames per second (fps) are used. The use of digital methods reduces the amount of radiation required and also the heat generated by the x-ray tube. Images can therefore be produced using a very small focal spot on the x-ray tube, which can produce further improvement in the resolution of the clinical images.

  15. Final design review report for K Basin Dose Reduction Project Clean and Coat Task

    SciTech Connect

    Blackburn, L.D.

    1996-02-01

    The strategy for reducing radiation dose originating from radionuclides absorbed in the concrete is to raise the pool water level to provide additional shielding. The concrete walls need to be coated to prevent future radionuclide absorption into the walls. This report documents a final design review of equipment to clean and coat basin walls. The review concluded that the design presented was acceptable for release for fabrication.

  16. Conceptual design review report for K Basin Dose Reduction Project clean and coat task

    SciTech Connect

    Blackburn, L.D.

    1996-01-01

    The strategy for reducing radiation dose originating from radionuclides absorbed in the concrete is to raise the pool water level to provide additional shielding. The concrete walls need to be coated to prevent future radionuclide absorption into the walls. This report documents a conceptual design review of equipment to clean and coat basin walls. The review concluded that the proposed concepts were and acceptable basis for proceeding with detailed final design.

  17. Reduction of the ventricular arrhythmogenic dose of epinephrine by ketamine administration in halothane-anesthetized cats.

    PubMed

    Bednarski, R M; Sams, R A; Majors, L J; Ashcraft, S

    1988-03-01

    The effect of ketamine administration on the ventricular arrhythmogenic dose of epinephrine (VADE) was studied in 4 halothane-anesthetized cats. Each cat was anesthetized 4 times, 1 week apart, with halothane (end-tidal concentration, 1.5%) and with halothane (end-tidal concentration, 1.5%) combined with ketamine infusion (50, 100, and 200 micrograms/kg of body weight/min). Epinephrine was infused in progressively increasing doses. The VADE (micrograms/kg) was calculated as the product of infusion rate of epinephrine and time of infusion necessary to induce 4 or more ventricular premature depolarizations within 15 s. The mean (+/- SD) VADE during halothane anesthesia was 1.1 (+/- 0.30) micrograms/kg. Ketamine infusion significantly (P less than 0.01) lowered the VADE independently of dose. The dose of epinephrine (micrograms/kg) that induced an ECG change in P-wave configuration was calculated similarly. Less epinephrine was necessary to induce a change in P-wave configuration than was necessary to induce 4 or more ventricular premature depolarizations within 15 s. Blood samples were collected after 4 hours of ketamine infusion and again immediately after determination of the VADE for analysis of plasma ketamine and norketamine concentrations by use of gas chromatography. Plasma ketamine and norketamine concentrations after a 4-hour infusion and immediately after determination of the VADE were similar for any given ketamine infusion rate, indicating that steady-state plasma concentrations had been reached for each infusion rate. Blood pressure and heart rate were measured immediately before (base line) and immediately after infusion of the VADE. Ketamine infusion significantly (P less than 005) lowered base-line blood pressure, but not heart rate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3358546

  18. X-Ray Dose Reduction in Abdominal Computed Tomography Using Advanced Iterative Reconstruction Algorithms

    PubMed Central

    Ning, Peigang; Zhu, Shaocheng; Shi, Dapeng; Guo, Ying; Sun, Minghua

    2014-01-01

    Objective This work aims to explore the effects of adaptive statistical iterative reconstruction (ASiR) and model-based iterative reconstruction (MBIR) algorithms in reducing computed tomography (CT) radiation dosages in abdominal imaging. Methods CT scans on a standard male phantom were performed at different tube currents. Images at the different tube currents were reconstructed with the filtered back-projection (FBP), 50% ASiR and MBIR algorithms and compared. The CT value, image noise and contrast-to-noise ratios (CNRs) of the reconstructed abdominal images were measured. Volumetric CT dose indexes (CTDIvol) were recorded. Results At different tube currents, 50% ASiR and MBIR significantly reduced image noise and increased the CNR when compared with FBP. The minimal tube current values required by FBP, 50% ASiR, and MBIR to achieve acceptable image quality using this phantom were 200, 140, and 80 mA, respectively. At the identical image quality, 50% ASiR and MBIR reduced the radiation dose by 35.9% and 59.9% respectively when compared with FBP. Conclusions Advanced iterative reconstruction techniques are able to reduce image noise and increase image CNRs. Compared with FBP, 50% ASiR and MBIR reduced radiation doses by 35.9% and 59.9%, respectively. PMID:24664174

  19. [5 years of "concerted action dose reduction in CT" -- what has been achieved and what remains to be done?].

    PubMed

    Nagel, H D; Blobel, J; Brix, G; Ewen, K; Galanski, M; Höfs, P; Loose, R; Prokop, M; Schneider, K; Stamm, G; Stender, H-S; Süss, C; Türkay, S; Vogel, H; Wucherer, M

    2004-11-01

    In May 1998, the German "Concerted Action Dose Reduction in CT" was founded by all parties involved in CT. Its intention was to achieve a significant reduction of the radiation exposure caused by CT, a matter that has increasingly been considered a major challenge since the early nineties. As a result of a number of joint efforts, the essential preconditions have been established by now. The fifth anniversary of the Concerted Action gave rise for both retrospection and outlook on the tasks that have already been accomplished and those that still need to be done. For this purpose, a one-day symposium took place in Berlin on November 4, 2003. The contents of a total of 18 contributions will be outlined here in brief. PMID:15497088

  20. Radiation dose reduction and new image modalities development for interventional C-arm imaging system

    NASA Astrophysics Data System (ADS)

    Niu, Kai

    Cardiovascular disease and stroke are the leading health problems and causes of death in the US. Due to the minimally invasive nature of the evolution of image guided techniques, interventional radiological procedures are becoming more common and are preferred in treating many cardiovascular diseases and strokes. In addition, with the recent advances in hardware and device technology, the speed and efficacy of interventional treatment has significantly improved. This implies that more image modalities can be developed based on the current C-arm system and patients treated in interventional suites can potentially experience better health outcomes. However, during the treatment patients are irradiated with substantial amounts of ionizing radiation with a high dose rate (digital subtraction angiography (DSA) with 3muGy/frame and 3D cone beam CT image with 0.36muGy/frame for a Siemens Artis Zee biplane system) and/or a long irradiation time (a roadmapping image sequence can be as long as one hour during aneurysm embolization). As a result, the patient entrance dose is extremely high. Despite the fact that the radiation dose is already substantial, image quality is not always satisfactory. By default a temporal average is used in roadmapping images to overcome poor image quality, but this technique can result in motion blurred images. Therefore, reducing radiation dose while maintaining or even improving the image quality is an important area for continued research. This thesis is focused on improving the clinical applications of C-arm cone beam CT systems in two ways: (1) Improve the performance of current image modalities on the C-arm system. (2) Develop new image modalities based on the current system. To be more specific, the objectives are to reduce radiation dose for current modalities (e.g., DSA, fluoroscopy, roadmapping, and cone beam CT) and enable cone beam CT perfusion and time resolved cone beam CT angiography that can be used to diagnose and triage acute

  1. A two-stage sequential linear programming approach to IMRT dose optimization

    PubMed Central

    Zhang, Hao H; Meyer, Robert R; Wu, Jianzhou; Naqvi, Shahid A; Shi, Leyuan; D’Souza, Warren D

    2010-01-01

    The conventional IMRT planning process involves two stages in which the first stage consists of fast but approximate idealized pencil beam dose calculations and dose optimization and the second stage consists of discretization of the intensity maps followed by intensity map segmentation and a more accurate final dose calculation corresponding to physical beam apertures. Consequently, there can be differences between the presumed dose distribution corresponding to pencil beam calculations and optimization and a more accurately computed dose distribution corresponding to beam segments that takes into account collimator-specific effects. IMRT optimization is computationally expensive and has therefore led to the use of heuristic (e.g., simulated annealing and genetic algorithms) approaches that do not encompass a global view of the solution space. We modify the traditional two-stage IMRT optimization process by augmenting the second stage via an accurate Monte-Carlo based kernel-superposition dose calculations corresponding to beam apertures combined with an exact mathematical programming based sequential optimization approach that uses linear programming (SLP). Our approach was tested on three challenging clinical test cases with multileaf collimator constraints corresponding to two vendors. We compared our approach to the conventional IMRT planning approach, a direct-aperture approach and a segment weight optimization approach. Our results in all three cases indicate that the SLP approach outperformed the other approaches, achieving superior critical structure sparing. Convergence of our approach is also demonstrated. Finally, our approach has also been integrated with a commercial treatment planning system and may be utilized clinically. PMID:20071764

  2. An aminoglycoside dosing program using the Casio FX-700P pocket computer.

    PubMed

    Yutani, R M

    1985-06-01

    The utilization of the desktop microcomputer, programmable calculator, and scientific calculator has simplified the management of formulas used in pharmacokinetic drug monitoring. However, each is limited by either high cost, lack of portability, or difficulty in operation. The pocket computer offers a solution to these problems. Using the CASIO FX-700P as an example, an aminoglycoside dosing program is presented together with a program listing and sample cases demonstrating its use. PMID:10278328

  3. Data reduction programs for a laser radar system

    NASA Astrophysics Data System (ADS)

    Badavi, F. F.; Copeland, G. E.

    1984-01-01

    The listing and description of software routines which were used to analyze the analog data obtained from LIDAR - system are given. All routines are written in FORTRAN - IV on a HP - 1000/F minicomputer which serves as the heart of the data acquisition system for the LIDAR program. This particular system has 128 kilobytes of highspeed memory and is equipped with a Vector Instruction Set (VIS) firmware package, which is used in all the routines, to handle quick execution of different long loops. The system handles floating point arithmetic in hardware in order to enhance the speed of execution. This computer is a 2177 C/F series version of HP - 1000 RTE-IVB data acquisition computer system which is designed for real time data capture/analysis and disk/tape mass storage environment.

  4. Pollution Reduction Technology Program, Turboprop Engines, Phase 1

    NASA Technical Reports Server (NTRS)

    Anderson, R. D.; Herman, A. S.; Tomlinson, J. G.; Vaught, J. M.; Verdouw, A. J.

    1976-01-01

    Exhaust pollutant emissions were measured from a 501-D22A turboprop engine combustor and three low emission combustor types -- reverse flow, prechamber, and staged fuel, operating over a fuel-air ratio range of .0096 to .020. The EPAP LTO cycle data were obtained for a total of nineteen configurations. Hydrocarbon emissions were reduced from 15.0 to .3 lb/1000 Hp-Hr/cycle, CO from 31.5 to 4.6 lb/1000 Hp-Hr/cycle with an increase in NOx of 17 percent, which is still 25% below the program goal. The smoke number was reduced from 59 to 17. Emissions given here are for the reverse flow Mod. IV combustor which is the best candidate for further development into eventual use with the 501-D22A turboprop engine. Even lower emissions were obtained with the advanced technology combustors.

  5. Biological assessment for the effluent reduction program, Los Alamos National Laboratory, Los Alamos, New Mexico

    SciTech Connect

    Cross, S.P.

    1996-08-01

    This report describes the biological assessment for the effluent recution program proposed to occur within the boundaries of Los Alamos National Laboratory. Potential effects on wetland plants and on threatened and endangered species are discussed, along with a detailed description of the individual outfalls resulting from the effluent reduction program.

  6. Issues in the Outcome Evaluation of a Math Anxiety Reduction Program for Teacher Education Students.

    ERIC Educational Resources Information Center

    Tittle, Carol Kehr; Denker, Elenor Rubin

    A project was designed to evaluate TEAM, a math anxiety reduction program for undergraduate students preparing to be elementary school teachers. The program consisted of two main components: (1) instruction intended to improve problem solving skills using the areas of patterns, probability, measurement, approximation, and estimation; and (2)…

  7. 77 FR 19004 - Fishing Capacity Reduction Program for the Southeast Alaska Purse Seine Salmon Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-29

    ... on May 23, 2011 (76 FR 29707), and final program regulations on October 6, 2011 (76 FR 61986), to implement the reduction program. NMFS published the list of eligible voters in on March 1, 2012 (77 FR 12568... Southeast Alaska Purse Seine Salmon Fishery AGENCY: National Marine Fisheries Service (NMFS),...

  8. An Original Behavior Modification Program for Weight Reduction: Minimal Intervention and Permanent Habit Change.

    ERIC Educational Resources Information Center

    Lublin, Irwin; Kirkish, Patricia

    This description of a weight reduction program, based on generalizations derived from eight years of work with overweight persons, discusses the clients' rationalization of overeating behaviors. In this behavior modification program, the client is required to permanently give up one high calorie food and to write down all foods eaten before actual…

  9. Findings from the Evaluation of OJJDP's Gang Reduction Program. Juvenile Justice Bulletin

    ERIC Educational Resources Information Center

    Cahill, Meagan; Hayeslip, David

    2010-01-01

    This bulletin draws on findings from an independent evaluation, conducted by the Urban Institute, of the Gang Reduction Program's (GRP) Impact in Los Angeles, California; Milwaukee, Wisconsin; North Miami Beach, Florida; and Richmond, Virginia, to examine how effectively these sites implemented the program. Following are some of the authors' key…

  10. Effects of Participation in a Sexual Assault Risk Reduction Program on Psychological Distress following Revictimization

    ERIC Educational Resources Information Center

    Mouilso, Emily R.; Calhoun, Karen S.; Gidycz, Christine A.

    2011-01-01

    The current study followed women who participated in a sexual assault risk reduction program and a wait-list control group for 4 months. Those women in both groups who reported being revictimized (N = 147) were assessed to determine the effect of program participation on psychological distress. Intervention group participants reported a…