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Sample records for edema-induced dose reductions

  1. 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.

  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. Escin attenuates cerebral edema induced by acute omethoate poisoning.

    PubMed

    Wang, Tian; Jiang, Na; Han, Bing; Liu, Wenbo; Liu, Tongshen; Fu, Fenghua; Zhao, Delu

    2011-06-01

    Organophosphorus exposure affects different organs such as skeletal muscles, the gastrointestinal tract, liver, lung, and brain. The present experiment aimed to evaluate the effect of escin on cerebral edema induced by acute omethoate poisoning. Sprague-Dawley rats were administered subcutaneously with omethoate at a single dose of 60 mg/kg followed by escin treatment. The results showed that escin reduced the brain water content and the amount of Evans blue in omethoate-poisoned animals. Treatment with escin decreased the levels of tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase-9 (MMP-9), cyclooxygenase-2 (COX-2), and prostaglandin E₂ (PGE₂) in the brain. Escin also alleviated the histopathological change induced by acute omethoate poisoning. The findings demonstrated that escin can attenuate cerebral edema induced by acute omethoate poisoning, and the underlying mechanism was associated with ameliorating the permeability of the blood-brain barrier.

  4. Cerebral edema induced in mice by a convulsive dose of soman. Evaluation through diffusion-weighted magnetic resonance imaging and histology

    SciTech Connect

    Testylier, Guy . E-mail: guytestylier@crssa.net; Lahrech, Hana; Montigon, Olivier; Foquin, Annie; Delacour, Claire; Bernabe, Denis; Segebarth, Christoph; Dorandeu, Frederic; Carpentier, Pierre

    2007-04-15

    Purpose: In the present study, diffusion-weighted magnetic resonance imaging (DW-MRI) and histology were used to assess cerebral edema and lesions in mice intoxicated by a convulsive dose of soman, an organophosphate compound acting as an irreversible cholinesterase inhibitor. Methods: Three hours and 24 h after the intoxication with soman (172 {mu}g/kg), the mice were anesthetized with an isoflurane/N{sub 2}O mixture and their brain examined with DW-MRI. After the imaging sessions, the mice were sacrificed for histological analysis of their brain. Results: A decrease in the apparent diffusion coefficient (ADC) was detected as soon as 3 h after the intoxication and was found strongly enhanced at 24 h. A correlation was obtained between the ADC change and the severity of the overall brain damage (edema and cellular degeneration): the more severe the damage, the stronger the ADC drop. Anesthesia was shown to interrupt soman-induced seizures and to attenuate edema and cell change in certain sensitive brain areas. Finally, brain water content was assessed using the traditional dry/wet weight method. A significant increase of brain water was observed following the intoxication. Conclusions: The ADC decrease observed in the present study suggests that brain edema in soman poisoning is mainly intracellular and cytotoxic. Since entry of water into Brain was also evidenced, this type of edema is certainly mixed with others (vasogenic, hydrostatic, osmotic). The present study confirms the potential of DW-MRI as a non-invasive tool for monitoring the acute neuropathological consequences (edema and neurodegeneration) of soman-induced seizures.

  5. Pharmacological reduction of brain edema induced by intracarotid infusion of protamine sulphate: a comparison between a free radical scavenger and an AMPA receptor antagonist.

    PubMed

    Johansson, B B; Westergren, I

    1994-01-01

    The blood-brain barrier (BBB) of rats was opened by infusing 10 mg protamine sulphate (200 microliters in 30 s) into the right internal carotid artery. Ten minutes later, tirilazad, a 21-aminosteroid (3 mg/kg): NBQX, an AMPA receptor antagonist (5 mg/kg); or dixyrazine, a phenotiazine derivate (10 mg/kg), was administered intravenously and the rats were killed 2 h after protamine infusion. Brain specific gravity was determined in the frontal, parietal and occipital cortex and in the striatum. In separate experiments, serum albumin content was determined in the brain of rats by immunoelectrophoresis 2 h after protamine infusion with or without tirilazad pretreatment. Specific gravity was significantly higher in all of the studied brain regions in rats given tirilazad or NBQX than in those given vehicle or dixyrazine (p < 0.001). A combination of tirilazad and NBQX was significantly more efficient than either drug alone in reducing edema in the occipital cortex (p < 0.05) and more efficient than NBQX alone in the frontal and parietal cortex (p < 0.05). None of the drugs reduced the albumin content in CSF; in addition, tirilazad failed to reduce albumin extravasation in the brain and CSF when given before protamine infusion. We conclude that the anti-edematous effect of tirilazad and NBQX is related to cellular events within the brain and not to a reduction of leakage over the BBB.

  6. Ability of eugenol to reduce tongue edema induced by Dieffenbachia picta Schott in mice.

    PubMed

    Dip, Etyene Castro; Pereira, Nuno Alvarez; Fernandes, Patricia Dias

    2004-05-01

    Dieffenbachia picta Schott (Araceae), known in Brazil as "comigo-ninguém-pode" is an ornamental plant with toxic properties. Its juice, when chewed, causes a painful edema of the oral mucous membranes, buccal ulcerations and tongue hypertrophy. This acute inflammation sometimes becomes severe enough to produce glottis obstruction, respiratory compromise and death. Eugenol (4-alil-2-metoxiphenol), the essential oil extracted from Caryophyllus aromaticus (Myrtaceae) is widely used in odontology. In this study, our objective was to standardize, in mice, a measurable methodology for the tongue edema induced by the topical application of the D. picta stem juice; evaluate the effects of eugenol in this model and compare the results with emergency treatment used in hospitals. Our results show that in spite of a small increase in edema a few minutes after administration, emergency treatment reduced by 70% the overall edema. When compared with the combination of the above drugs, eugenol, even at the smallest dose of 5 microg/kg, regardless of the chosen administration route, or the moment the treatment began, presents better results in the reduction and inhibition of the tongue edema induced by the D. picta juice.

  7. The Effects of Aquaporin-1 in Pulmonary Edema Induced by Fat Embolism Syndrome

    PubMed Central

    Zhang, Yiwei; Tian, Kun; Wang, Yan; Zhang, Rong; Shang, Jiawei; Jiang, Wei; Wang, Aizhong

    2016-01-01

    This study was designed to investigate the role of aquaporin1 (AQP1) in the pathologic process of pulmonary edema induced by fat embolism syndrome (FES) and the effects of a free fatty acid (FFA) mixture on AQP1 expression in pulmonary microvascular endothelial cells (PMVECs). In vivo, edema was more serious in FES mice compared with the control group. The expression of AQP1 and the wet-to-dry lung weight ratio (W/D) in the FES group were significantly increased compared with the control group. At the same time, inhibition of AQP1 decreased the pathological damage resulting from pulmonary edema. Then we performed a study in vitro to investigate whether AQP1 was induced by FFA release in FES. The mRNA and protein level of AQP1 were increased by FFAs in a dose- and time-dependent manner in PMVECs. In addition, the up-regulation of AQP1 was blocked by the inhibitor of p38 kinase, implicating the p38 MAPK pathway as involved in the FFA-induced AQP1 up-regulation in PMVECs. Our results demonstrate that AQP1 may play important roles in pulmonary edema induced by FES and can be regarded as a new therapy target for treatment of pulmonary edema induced by FES. PMID:27455237

  8. The Effects of Aquaporin-1 in Pulmonary Edema Induced by Fat Embolism Syndrome.

    PubMed

    Zhang, Yiwei; Tian, Kun; Wang, Yan; Zhang, Rong; Shang, Jiawei; Jiang, Wei; Wang, Aizhong

    2016-07-21

    This study was designed to investigate the role of aquaporin1 (AQP1) in the pathologic process of pulmonary edema induced by fat embolism syndrome (FES) and the effects of a free fatty acid (FFA) mixture on AQP1 expression in pulmonary microvascular endothelial cells (PMVECs). In vivo, edema was more serious in FES mice compared with the control group. The expression of AQP1 and the wet-to-dry lung weight ratio (W/D) in the FES group were significantly increased compared with the control group. At the same time, inhibition of AQP1 decreased the pathological damage resulting from pulmonary edema. Then we performed a study in vitro to investigate whether AQP1 was induced by FFA release in FES. The mRNA and protein level of AQP1 were increased by FFAs in a dose- and time-dependent manner in PMVECs. In addition, the up-regulation of AQP1 was blocked by the inhibitor of p38 kinase, implicating the p38 MAPK pathway as involved in the FFA-induced AQP1 up-regulation in PMVECs. Our results demonstrate that AQP1 may play important roles in pulmonary edema induced by FES and can be regarded as a new therapy target for treatment of pulmonary edema induced by FES.

  9. Pulmonary edema induced by calcium-channel blockade for tocolysis.

    PubMed

    Bal, Laurence; Thierry, Stéphane; Brocas, Elsa; Adam, Marie; Van de Louw, Andry; Tenaillon, Alain

    2004-09-01

    Nicardipine is used in the treatment of premature labor. There are no previous reports in the anesthesia literature of serious side effects associated with this drug. We report a case of pulmonary edema induced by nicardipine therapy for tocolysis in a pregnant 27-yr-old patient admitted to our hospital for preterm labor with intact membranes at 27 wk of gestation.

  10. Involvement of mast cells and histamine in edema induced in mice by Scolopendra viridicornis centipede venom.

    PubMed

    Távora, Bianca C L F; Kimura, Louise F; Antoniazzi, Marta M; Chiariello, Thiago M; Faquim-Mauro, Eliana L; Barbaro, Katia C

    2016-10-01

    Bites caused by Scolopendra viridicornis centipede are mainly characterized by burning pain, paresthesia and edema. On this regard, the aim of this work was to study the involvement of mast cells and histamine in edema induced by Scolopendra viridicornis (Sv) centipede venom. The edema was analyzed on mice paws. The mice were pretreated with cromolyn (mast cell degranulation inhibitor) and antagonists of histamine receptors, such as promethazine (H1R), cimetidine (H2R) and thioperamide (H3/H4R). The analyses were carried out at different times after the injection of Sv venom (15 μg) or PBS in the footpad of mice. Our results showed a significant inhibition of the edema induced by Sv venom injection in mice previously treated: cromolyn (38-91%), promethazine (50-59%) and thioperamide (around 30%). The treatment with cimetidine did not alter the edema induced by Sv venom. Histopathological analysis showed that Sv venom injection (15 μg) induced edema, leukocyte recruitment and mast cells degranulation, when compared with the PBS-injected mice. Direct effects of the Sv venom on mast cells were studied in PT-18 line (mouse mast cell) and RBL-2H3 cells (rat mast cells). The data showed that higher doses (3.8 and 7.5 μg) of Sv venom were cytotoxic for both cell lineages and induced morphological changes. However, lower doses of the venom induced degranulation of both mast cell lines, as well as the secretion of MCP-1, IL-6 and IL-1β. The production of PGD2 was only observed in the RBL-2H3 line incubated with Sv venom. Taking our results together, we demonstrated that upon Sv venom exposure, mast cells and histamine are crucial for the establishment of the local inflammatory reaction.

  11. Dose reduction at nuclear power plants

    SciTech Connect

    Baum, J.W.; Dionne, B.J.

    1983-01-01

    The collective dose equivalent at nuclear power plants increased from 1250 rem in 1969 to nearly 54,000 rem in 1980. This rise is attributable primarily to an increase in nuclear generated power from 1289 MW-y to 29,155 MW-y; and secondly, to increased average plant age. However, considerable variation in exposure occurs from plant to plant depending on plant type, refueling, maintenance, etc. In order to understand the factors influencing these differences, an investigation was initiated to study dose-reduction techniques and effectiveness of as low as reasonably achievable (ALARA) planning at light water plants. Objectives are to: identify high-dose maintenance tasks and related dose-reduction techniques; investigate utilization of high-reliability, low-maintenance equipment; recommend improved radioactive waste handling equipment and procedures; examine incentives for dose reduction; and compile an ALARA handbook.

  12. 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

  13. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Transcriptional effects of gene dose reduction

    PubMed Central

    2014-01-01

    Large-scale gene dose reductions usually lead to abnormal phenotypes or death. However, male mammals, Drosophila, and Caenorhabditis elegans have only one X chromosome and thus can be considered as monosomic for a major chromosome. Despite the deleterious effects brought about by such gene dose reduction in the case of an autosome, X chromosome monosomy in males is natural and innocuous. This is because of the nearly full transcriptional compensation for X chromosome genes in males, as opposed to no or partial transcriptional compensation for autosomal one-dose genes arising due to deletions. Buffering, the passive absorption of disturbance due to enzyme kinetics, and feedback responses triggered by expression change contribute to partial compensation. Feed-forward mechanisms, which are active responses to genes being located on the X, rather than actual gene dose are important contributors to full X chromosome compensation. In the last decade, high-throughput techniques have provided us with the tools to effectively and quantitatively measure the small-fold transcriptional effects of dose reduction. This is leading to a better understanding of compensatory mechanisms. PMID:24581086

  15. Structural requirements for the edema-inducing and hemolytic activities of mastoparan B isolated from the hornet (Vespa basalis) venom.

    PubMed

    Ho, C L; Lin, Y L; Chen, W C; Hwang, L L; Yu, H M; Wang, K T

    1996-09-01

    Mastoparan B (MP-B) is a cationic tetradecapeptide isolated from the black-bellied hornet (Vespa basalis) venom. It has a primary structure (LKLKSIVSWAKKVL-CONH2) distinct from other vespine mastoparans. The peptide caused a dose-dependent swelling in rat hind paw and showed a potent hemolytic activity in guinea pig red blood cells. Studies on the structure activity relationship of the peptide showed that replacing lysine at position 2 (Lys2) by asparagine (Asn) in the MP-B sequence caused about 40% decrease in its edema-inducing activity at 50 micrograms/paw and 90% decrease in hemolytic activity at 30 microM of the peptide, while the same substitution at Lys4 did not cause a significant change in either activity. Replacing either Lys11 or Lys12 by leucine (Leu) caused little or no decrease in the edema-inducing and hemolytic activities. Decreases in both activities were observed when both Lys11 and Lys12 were replaced by Leu. On the other hand, replacing tryptophan at position 9 (Trp9) by tyrosine or phenylalanine in MP-B sequence almost abolished its hemolytic activity, while the edema-inducing activity was only partially inhibited. Circular dichroism spectra of the peptides measured in 20% trifluoro-ethanol revealed that substitution of Lys and Trp did not cause a significant change in the conformation of MP-B. it appears that Lys2 is crucial for both hemolytic and edema-inducing activities of MP-B, while Trp9 is of special importance to the hemolytic activity of MP-B. Lys11 and Lys12 in MP-B probably play a lesser role in both activities.

  16. 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

  17. Validation of CT dose-reduction simulation

    PubMed Central

    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, which is

  18. 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

  19. 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.

  20. Dose Reduction in Tomosynthesis of the Wrist.

    PubMed

    Becker, Anton S; Martini, Katharina; Higashigaito, Kai; Guggenberger, Roman; Andreisek, Gustav; Frauenfelder, Thomas

    2017-01-01

    The purpose of this study was to quantitatively and qualitatively determine the impact of radiation dose reduction on the image noise and quality of tomosynthesis studies of the wrist. Imaging of six cadaver wrists was performed with tomosynthesis in anteroposterior position at a tube voltage of 60 kV and tube current of 80 mA and subsequently at 60 or 50 kV with different tube currents of 80, 40, or 32 mA. Dose-area products (DAP) were obtained from the electronically logged protocol. Image noise was measured with an ROI. Two independent and blinded readers evaluated all images. Interreader agreement was measured with a Cohen kappa. Readers assessed overall quality and delineation of soft tissue, cortical bone, and trabecular bone on a 4-point Likert scale. The highest DAP (3.892 ± 0.432 Gy · cm(2)) was recorded for images obtained with 60 kV and 80 mA; the lowest (0.857 ± 0.178 Gy · cm(2)) was recorded for images obtained with 50 kV and 32 mA. Noise was highest when a combination of 50 kV and 32 mA (389 ± 26.6) was used and lowest when a combination of 60 kV and 80 mA (218 ± 12.3) was used. The amount of noise on images acquired using 60 kV and 80 mA was statistically significantly different from the amount measured on all other images (p < 0.0001). Interreader agreement was excellent (κ = 0.93). Delineation of anatomy and overall quality were scored best on images obtained with 60 kV and 80 mA and worst on images obtained with 50 kV and 32 mA. The difference in delineation and quality on images obtained using 50 kV and 40 mA was not statistically significantly different compared with images obtained using 60 kV and 80 mA. Significant dose reduction for tomosynthesis of the wrist is possible while image quality and delineation of anatomic structures remain preserved.

  1. Six steps to a successful dose-reduction strategy

    SciTech Connect

    Bennett, M.

    1995-03-01

    The increased importance of demonstrating achievement of the ALARA principle has helped produce a proliferation of dose-reduction ideas. Across a company there may be many dose-reduction items being pursued in a variety of areas. However, companies have a limited amount of resource and, therefore, to ensure funding is directed to those items which will produce the most benefit and that all areas apply a common policy, requires the presence of a dose-reduction strategy. Six steps were identified in formulating the dose-reduction strategy for Rolls-Royce and Associates (RRA): (1) collating the ideas; (2) quantitatively evaluating them on a common basis; (3) prioritizing the ideas in terms of cost benefit, (4) implementation of the highest priority items; (5) monitoring their success; (6) periodically reviewing the strategy. Inherent in producing the dose-reduction strategy has been a comprehensive dose database and the RRA-developed dose management computer code DOMAIN, which allows prediction of dose rates and dose. The database enabled high task dose items to be identified, assisted in evaluating dose benefits, and monitored dose trends once items had been implemented. The DOMAIN code was used both in quantifying some of the project dose benefits and its results, such as dose contours, used in some of the dose-reduction items themselves. In all, over fifty dose-reduction items were evaluated in the strategy process and the items which will give greatest benefit are being implemented. The strategy has been successful in giving renewed impetus and direction to dose-reduction management.

  2. Radiation dose reduction in chest CT: a review.

    PubMed

    Kubo, Takeshi; Lin, Pei-Jan Paul; Stiller, Wolfram; Takahashi, Masaya; Kauczor, Hans-Ulrich; Ohno, Yoshiharu; Hatabu, Hiroto

    2008-02-01

    This article aims to summarize the available data on reducing radiation dose exposure in routine chest CT protocols. First, the general aspects of radiation dose in CT and radiation risk are discussed, followed by the effect of changing parameters on image quality. Finally, the results of previous radiation dose reduction studies are reviewed, and important information contributing to radiation dose reduction will be shared. A variety of methods and techniques for radiation dose reduction should be used to ensure that radiation exposure is kept as low as is reasonably achievable.

  3. Edema induced by Bothrops asper (Squamata: Viperidae) snake venom and its inhibition by Costa Rican plant extracts.

    PubMed

    Badilla, Beatriz; Chaves, Fernando; Mora, Gerardo; Poveda, Luis J

    2006-06-01

    We tested the capacity of leaf (Urera baccifera, Loasa speciosa, Urtica leptuphylla, Chaptalia nutans, and Satureja viminea) and root (Uncaria tomentosa) extracts to inhibit edema induced by Bothrops asper snake venom. Edema-forming activity was studied plethysmographically in the rat hind paw model. Groups of rats were injected intraperitoneally with various doses of each extract and, one hour later, venom was injected subcutaneously in the right hind paw. Edema was assessed at various time intervals. The edematogenic activity was inhibited in those animals that received an injection U. tomentosa, C. nutans or L. speciosa extract. The extract of U. baccifera showed a slight inhibition of the venom effect. Extract from S. viminea and, to a lesser extent that of U. leptuphylla, induced a pro-inflammatory effect, increasing the edema at doses of 250 mg/kg at one and two hours.

  4. Dose reduction in paediatric MDCT: general principles.

    PubMed

    Paterson, A; Frush, D P

    2007-06-01

    The number of multi-detector array computed tomography (MDCT) examinations performed per annum continues to increase in both the adult and paediatric populations. Estimates from 2003 suggested that CT contributed 17% of a radiology department's workload, yet was responsible for up to 75% of the collective population dose from medical radiation. The effective doses for some CT examinations today overlap with those argued to have an increased risk of cancer. This is especially pertinent for paediatric CT, as children are more radiosensitive than adults (and girls more radiosensitive than boys). In addition, children have a longer life ahead of them, in which radiation induced cancers may become manifest. Radiologists must be aware of these facts and practise the ALARA (as low as is reasonably achievable) principle, when it comes to deciding CT protocols and parameters.

  5. Radiation dose-reduction strategies in thoracic CT.

    PubMed

    Moser, J B; Sheard, S L; Edyvean, S; Vlahos, I

    2017-05-01

    Modern computed tomography (CT) machines have the capability to perform thoracic CT for a range of clinical indications at increasingly low radiation doses. This article reviews several factors, both technical and patient-related, that can affect radiation dose and discusses current dose-reduction methods relevant to thoracic imaging through a review of current techniques in CT acquisition and image reconstruction. The fine balance between low radiation dose and high image quality is considered throughout, with an emphasis on obtaining diagnostic quality imaging at the lowest achievable radiation dose. The risks of excessive radiation dose reduction are also considered. Inappropriately low dose may result in suboptimal or non-diagnostic imaging that may reduce diagnostic confidence, impair diagnosis, or result in repeat examinations incurring incremental ionising radiation exposure. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  6. 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.

  7. Estimation of breast dose reduction potential for organ-based tube current modulated CT with wide dose reduction arc

    NASA Astrophysics Data System (ADS)

    Fu, Wanyi; Sturgeon, Gregory M.; Agasthya, Greeshma; Segars, W. Paul; Kapadia, Anuj J.; Samei, Ehsan

    2017-03-01

    This study aimed to estimate the organ dose reduction potential for organ-dose-based tube current modulated (ODM) thoracic CT with wide dose reduction arc. Twenty-one computational anthropomorphic phantoms (XCAT, age range: 27- 75 years, weight range: 52.0-105.8 kg) were used to create a virtual patient population with clinical anatomic variations. For each phantom, two breast tissue compositions were simulated: 50/50 and 20/80 (glandular-to-adipose ratio). A validated Monte Carlo program was used to estimate the organ dose for standard tube current modulation (TCM) (SmartmA, GE Healthcare) and ODM (GE Healthcare) for a commercial CT scanner (Revolution, GE Healthcare) with explicitly modeled tube current modulation profile, scanner geometry, bowtie filtration, and source spectrum. Organ dose was determined using a typical clinical thoracic CT protocol. Both organ dose and CTDIvol-to-organ dose conversion coefficients (h factors) were compared between TCM and ODM. ODM significantly reduced all radiosensitive organ doses (p<0.01). The breast dose was reduced by 30+/-2%. For h factors, organs in the anterior region (e.g. thyroid, stomach) exhibited substantial decreases, and the medial, distributed, and posterior region either saw an increase or no significant change. The organ-dose-based tube current modulation significantly reduced organ doses especially for radiosensitive superficial anterior organs such as the breasts.

  8. Pediatric interventional radiology and dose-reduction techniques.

    PubMed

    Johnson, Craig; Martin-Carreras, Teresa; Rabinowitz, Deborah

    2014-08-01

    The pediatric interventional radiology community has worked diligently in recent years through education and the use of technology to incorporate numerous dose-reduction strategies. This article seeks to describe different strategies where we can significantly lower the dose to the pediatric patient undergoing a diagnostic or therapeutic image-guided procedure and, subsequently, lower the dose several fold to the staff and ourselves in the process. These strategies start with patient selection, dose awareness and monitoring, shielding, fluoroscopic techniques, and collimation. Advanced features such as cone-beam technology, dose-reduction image processing algorithms, overlay road mapping, and volumetric cross-sectional hybrid imaging are also discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Dose Reduction with Adaptive Bolus Chasing Computed Tomography Angiography

    PubMed Central

    Cai, Zhijun; Bai, Er-Wei; Wang, Ge; Sharafuddin, Melhem J.; Abada, Hicham T.

    2010-01-01

    Computed Tomography (CT) has become an effective diagnosis and evaluating tool in clinical; however, its radiation exposure has drawn great attention as more and more CT scans are performed every year. How to reduce the radiation dose and meanwhile keep the resultant CT images diagnosable becomes an important research topic. In this paper, we propose a dose reduction approach along with the adaptive bolus chasing CT Angiography (CTA) techniques, which are capable of tracking the contrast bolus peak over all the blood vessel segments during the CTA scan. By modulating the tube current (and collimator width) online, we can reduce the total radiation dose and maintain the contrast to noise ratio (CNR) of the blood vessel. Numerical experiments on reference DSA data sets show that by using the proposed dose reduction method, the effective radiation dose can be saved about 39%. PMID:20421701

  10. Dose reduction with adaptive bolus chasing computed tomography angiography.

    PubMed

    Cai, Zhijun; Bai, Er-Wei; Wang, Ge; Sharafuddin, Melhem J; Abada, Hicham T

    2010-01-01

    Computed Tomography (CT) has become an effective diagnosis and evaluating tool in clinical; however, its radiation exposure has drawn great attention as more and more CT scans are performed every year. How to reduce the radiation dose and meanwhile keep the resultant CT images diagnosable becomes an important research topic. In this paper, we propose a dose reduction approach along with the adaptive bolus chasing CT Angiography (CTA) techniques, which are capable of tracking the contrast bolus peak over all the blood vessel segments during the CTA scan. By modulating the tube current (and collimator width) online, we can reduce the total radiation dose and maintain the contrast to noise ratio (CNR) of the blood vessel. Numerical experiments on reference DSA data sets show that by using the proposed dose reduction method, the effective radiation dose can be saved about 39%.

  11. 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

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

    PubMed

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

    2009-10-01

    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.

  13. A chronic opioid therapy dose reduction policy in primary care.

    PubMed

    Weimer, Melissa B; Hartung, Daniel M; Ahmed, Sharia; Nicolaidis, Christina

    2016-01-01

    High-dose opioids prescribed for the treatment of chronic pain have been associated with increased risk of opioid overdose. Health systems and states have responded by developing opioid dose limitation policies. Little is known about how these policies affect prescribing practices or characteristics of patients who respond best to opioid tapers from high-dose opioids. We conducted a retrospective cohort study to evaluate change in total opioid dose after the implementation of a provider education intervention and a 120 mg morphine equivalents per day (MED) opioid dose limitation policy in one academic primary care clinic. We compared opioid prescriptions 1 year before and 1 year after the intervention. We used univariate and multivariate logistic regression to assess which patient characteristics predicted opioid dose reduction from high opioid dose. Out of a total of 516 patients prescribed chronic opioid therapy, 116 patients (22%) were prescribed high-dose opioid therapy (>120 mg MED). After policy adoption, the average daily dose of opioids declined by 64 mg MED (95% confidence interval [CI]: 32-96; P < .001) and 41 patients (37%) on high-dose opioids tapered their doses below 120 mg MED (Tapered to Safer Dose group). In multivariate analyses, female sex was the only significant association with dose taper; female patients were less likely to taper to a safer dose (adjusted odds ratio [aOR] = 0.28, 95% CI: 0.11-0.70). A combined intervention of education and a practice policy that limits opioid doses for patients prescribed chronic opioid therapy may be an important component of system-level strategies to reduce opioid misuse and overdose; it may also help identify patients suitable for medication-assisted treatment for opioid use disorder. Specific strategies may be needed to assist women with opioid dose tapers.

  14. Dose reduction in chest CT: comparison of the adaptive iterative dose reduction 3D, adaptive iterative dose reduction, and filtered back projection reconstruction techniques.

    PubMed

    Yamada, Yoshitake; Jinzaki, Masahiro; Hosokawa, Takahiro; Tanami, Yutaka; Sugiura, Hiroaki; Abe, Takayuki; Kuribayashi, Sachio

    2012-12-01

    To assess the effectiveness of adaptive iterative dose reduction (AIDR) and AIDR 3D in improving the image quality in low-dose chest CT (LDCT). Fifty patients underwent standard-dose chest CT (SDCT) and LDCT simultaneously, performed under automatic exposure control with noise index of 19 and 38 (for a 2-mm slice thickness), respectively. The SDCT images were reconstructed with filtered back projection (SDCT-FBP images), and the LDCT images with FBP, AIDR and AIDR 3D (LDCT-FBP, LDCT-AIDR and LDCT-AIDR 3D images, respectively). On all the 200 lung and 200 mediastinal image series, objective image noise and signal-to-noise ratio (SNR) were measured in several regions, and two blinded radiologists independently assessed the subjective image quality. Wilcoxon's signed rank sum test with Bonferroni's correction was used for the statistical analyses. The mean dose reduction in LDCT was 64.2% as compared with the dose in SDCT. LDCT-AIDR 3D images showed significantly reduced objective noise and significantly increased SNR in all regions as compared to the SDCT-FBP, LDCT-FBP and LDCT-AIDR images (all, P ≤ 0.003). In all assessments of the image quality, LDCT-AIDR 3D images were superior to LDCT-AIDR and LDCT-FBP images. The overall diagnostic acceptability of both the lung and mediastinal LDCT-AIDR 3D images was comparable to that of the lung and mediastinal SDCT-FBP images. AIDR 3D is superior to AIDR. Intra-individual comparisons between SDCT and LDCT suggest that AIDR 3D allows a 64.2% reduction of the radiation dose as compared to SDCT, by substantially reducing the objective image noise and increasing the SNR, while maintaining the overall diagnostic acceptability. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  15. Dose reduction in pediatric computed tomography with automated exposure control.

    PubMed

    Alibek, Sedat; Brand, Martin; Suess, Christoph; Wuest, Wolfgang; Uder, Michael; Greess, Holger

    2011-06-01

    Since the introduction of computed tomographic (CT) imaging in the 1970s, the number of examinations has increased steadily. CT imaging is an essential part of routine workup in diagnostic radiology. The great advantage of multidetector computed tomography is the acquisition of a large amount of data in a short time period, thus speeding up diagnostic procedures. To protect patients from unnecessary radiation exposure, different approaches have been developed. In this study, the efficacy of automated exposure control (AEC) software in multidetector CT imaging with a focus on dose reduction in pediatric examinations was assessed. Between August 2004 and September 2005, a total of 71 children (40 male, 31 female; age range, 2-13 years; mean age, 7.2 years) were examined using a multisource CT scanner. Three different regions (chest, upper abdomen, and pelvis) were examined. Overall image quality was assessed with a subjective scale (1 = excellent, 2 = diagnostic, 3 = nondiagnostic). For all examinations, AEC was used. From the scanner's patient protocol, dose-length product, volume CT dose index, and tube current-time product were calculated for each examination. With AEC, a mean dose reduction of 30.6% was calculated. Images were rated as excellent (n = 39) or diagnostic (n = 32). Nondiagnostic image quality was not seen. Dose-length product and volume CT dose index were reduced by 30.4% and 29.5%, respectively. Overall, a mean dose reduction of 30.1% of the effective dose (5.8 ± 3.1 vs 8.4 ± 4.6 mSv) was achieved (P < .001). With AEC software, a mean dose reduction of 30% without any loss in diagnostic image quality is possible. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  16. Quantifying the potential for dose reduction with visual grading regression

    PubMed Central

    Smedby, Ö; Fredrikson, M; De Geer, J; Borgen, L; Sandborg, M

    2013-01-01

    Objectives To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures. Methods Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters. Results For five image quality criteria in coronary CTA, dose reductions of 16–26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32–41%, and 3D filtering by 42–51%. Conclusions VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques. PMID:22723511

  17. Quantifying the potential for dose reduction with visual grading regression.

    PubMed

    Smedby, O; Fredrikson, M; De Geer, J; Borgen, L; Sandborg, M

    2013-01-01

    To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures. Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters. For five image quality criteria in coronary CTA, dose reductions of 16-26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32-41%, and 3D filtering by 42-51%. VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques.

  18. Quantifying the potential for dose reduction with visual grading regression.

    PubMed

    Smedby, O; Fredrikson, M; De Geer, J; Borgen, L; Sandborg, M

    2013-01-01

    Objectives To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures. Methods Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters. Results For five image quality criteria in coronary CTA, dose reductions of 16-26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32-41%, and 3D filtering by 42-51%. Conclusions VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques.

  19. 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.

  20. Reduction of uterus dose in clinical thoracic computed tomography.

    PubMed

    Danova, D; Keil, B; Kästner, B; Wulff, J; Fiebich, M; Zink, K; Klose, K J; Heverhagen, J T

    2010-12-01

    The aim of this study was to investigate the potential dose reduction in the uterus as a result of lead apron protection during thoracic CT scans. Moreover, the distribution of the radiation dose in the uterus was determined in order to obtain information about the ratio of internally and externally scattered radiation. The uterus doses during thoracic CT were determined by measuring organ doses using an Alderson-RANDO®-Phantom and thermoluminescent dosimeters. A 0.25 mm lead equivalent protective apron was used to shield the abdominal area. Three measurement conditions were evaluated: without lead apron, covered with lead apron and wrapped with lead apron. The uterus dose with and without shielding describes the mean value and standard deviation of all examinations and all measurement points in the organ. The uterus dose by thoracic CT was measured to be approximately 66.5 ± 3.1 µGy. If the abdomen is covered with a 0.25 mm Pb equivalent lead apron in the front area and on both sides, the uterus dose is reduced to 49.4 ± 2.8 µGy (26% reduction, p < 0.001). If a lead apron is wrapped around the abdomen, providing 0.50 mm Pb shielding in the anterior section due to overlap, and 0.25 mm Pb in the posterior section and on both sides, the uterus dose is reduced even more to 43.8 ± 2.5 µGy (34% reduction, p < 0.001). The dose distribution when the lead apron covers the abdomen shows that the shielding is effective for the scatter radiation that comes from the anterior part. Moreover, the wrapped apron protects the uterus from all directions and is even more effective for dose reduction than the covering apron. Our findings demonstrate that protective aprons are an effective dose reduction technique without additional costs and little effect on patient examination time. © Georg Thieme Verlag KG Stuttgart · New York.

  1. Conditioned Placebo Dose Reduction: A new treatment in ADHD?

    PubMed Central

    Sandler, Adrian D.; Glesne, Corrine E.; Bodfish, James W.

    2010-01-01

    Objective This study examined if pairing a placebo with stimulant medication produces a placebo response that allows children with ADHD to be maintained on a lower dose of stimulant medication. Primary aim was to determine the efficacy, side effects and acceptability of a novel conditioned placebo dose reduction (CPDR) procedure. Method Participants included 99 children ages 6 to 12 years with ADHD. After an initial double-blind dose finding to identify optimal dose of mixed amphetamine salts (MAS), subjects were randomly assigned to one of three treatments of eight weeks duration: (a) CPDR condition (50% Reduced Dose/Placebo– RD/P) or (b) a dose reduction only condition (Reduced Dose - RD) or (c) a no reduction condition (Full Dose–FD). The innovative CPDR procedure involved daily pairing of MAS dose with a visually distinctive placebo capsule administered in open label, with full disclosure of placebo use to subjects and parents. Results 70 children completed the study. There were no differences in subject retention among the three groups. Most subjects in the RD/P group remained stable during the treatment phase, whereas most in the RD group deteriorated. There was no difference in control of ADHD symptoms between the RD/P group and the FD group, and both RD/P and FD groups showed better ADHD control than the RD group. Treatment emergent side effects were lowest in the RD/P group. Conclusion Pairing placebos with stimulant medication elicits a placebo response that allows children with ADHD to be effectively treated on 50% of their optimal stimulant dose. PMID:20495473

  2. Strategies for reduction of radiation dose in cardiac multislice CT.

    PubMed

    Paul, Jean-François; Abada, Hicham T

    2007-08-01

    Because cardiac computed tomography (CT) (mainly coronary CT angiography) is a very promising technique, used more and more for coronary artery evaluation, the benefits and risks of this new low-invasive technique must be balanced. Radiation dose is a major concern for coronary CT angiography, especially in case of repeated examinations or in particular subgroups of patients (for example young female patients). Radiation dose to patient tends to increase from 16- to 64-slice CT. Radiation exposure in ECG-gated acquisitions may reach up to 40 mSv; considerable differences are attributable to the performance of CT machines, to technical dose-sparing tools, but also to radiological habits. Setting radiation dose at the lowest level possible should be a constant goal for the radiologist. Current technological tools are detailed in regard to their efficiency. Optimisation is necessary, by a judicious use of technological tools and also by individual adaptation of kV or mAs. This paper reviews the different current strategies for radiation dose reduction, keeping image quality constant. Data from the literature are discussed, and future technological developments are considered in regards to radiation dose reduction. The particular case of paediatric patients with congenital heart disease is also addressed.

  3. Radiation dose-reduction strategies for neuroradiology CT protocols.

    PubMed

    Smith, A B; Dillon, W P; Gould, R; Wintermark, M

    2007-10-01

    Within the past 2 decades, the number of CT examinations performed has increased almost 10-fold. This is in large part due to advances in multidetector-row CT technology, which now allows faster image acquisition and improved isotropic imaging. The increased use, along with multidetector technique, has led to a significantly increased radiation dose to the patient from CT studies. This places increased responsibility on the radiologist to ensure that CT examinations are indicated and that the "as low as reasonably achievable" concept is adhered to. Neuroradiologists are familiar with factors that affect patient dose such as pitch, milliamperes, kilovolt peak (kVp), collimation, but with increasing attention being given to dose reduction, they are looking for additional ways to further reduce the radiation associated with their CT protocols. In response to increasing concern, CT manufacturers have developed dose-reduction tools, such as dose modulation, in which the tube current is adjusted along with the CT acquisition, according to patient's attenuation. This review will describe the available techniques for reducing dose associated with neuroradiologic CT imaging protocols.

  4. 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.

  5. Radiation dose from cardiac computed tomography before and after implementation of radiation dose-reduction techniques.

    PubMed

    Raff, Gilbert L; Chinnaiyan, Kavitha M; Share, David A; Goraya, Tauqir Y; Kazerooni, Ella A; Moscucci, Mauro; Gentry, Ralph E; Abidov, Aiden

    2009-06-10

    Cardiac computed tomography angiography (CCTA) can accurately diagnose coronary artery disease, but radiation dose from this procedure is of concern. To determine whether a collaborative radiation dose-reduction program would be associated with reduced radiation dose in patients undergoing CCTA in a statewide registry over a 1-year period and to define its effect on image quality. A prospective, controlled, nonrandomized study conducted during a control period (July-August 2007), an intervention period (September 2007-April 2008), and a follow-up period (May-June 2008) at 15 hospital imaging centers participating in the Advanced Cardiovascular Imaging Consortium in Michigan, which included small community hospitals and large academic medical centers. A total of 4995 sequential patients undergoing CCTA for suspected coronary artery disease were enrolled; 4862 patients (97.3%) had complete radiation data for analysis. A best-practice CCTA scan model was used, which included minimized scan range, heart rate reduction, electrocardiographic-gated tube current modulation, and reduced tube voltage in suitable patients. Primary outcomes included dose-length product and effective radiation dose from all phases of the CCTA scan. Secondary outcomes were image quality assessed by a 4-point scale (1 indicated excellent; 2, good; 3, adequate; and 4, nondiagnostic) and frequency of diagnostic-quality scans. Compared with the control period, patients' estimated median radiation dose in the follow-up period was reduced by 53.3% (dose-length product decreased from 1493 mGy x cm [interquartile range {IQR}, 855-1823 mGy x cm] to 697 mGy x cm [IQR, 407-1163 mGy x cm]; P < .001) and effective dose from 21 mSv (IQR, 12-26 mSv) to 10 mSv (IQR, 6-16 mSv) (P < .001). The greatest reduction in dose occurred at low-volume sites. There were no significant changes in median image quality assessment during the control period compared with the follow-up period (median image quality of 2 [images

  6. Impact of new technologies on dose reduction in CT.

    PubMed

    Lee, Ting-Yim; Chhem, Rethy K

    2010-10-01

    The introduction of slip ring technology enables helical CT scanning in the late 1980's and has rejuvenated CT's role in diagnostic imaging. Helical CT scanning has made possible whole body scanning in a single breath hold and computed tomography angiography (CTA) which has replaced invasive catheter based angiography in many cases because of its easy of operation and lesser risk to patients. However, a series of recent articles and accidents have heightened the concern of radiation risk from CT scanning. Undoubtedly, the radiation dose from CT studies, in particular, CCTA studies, are among the highest dose studies in diagnostic imaging. Nevertheless, CT has remained the workhorse of diagnostic imaging in emergent and non-emergent situations because of their ubiquitous presence in medical facilities from large academic to small regional hospitals and their round the clock accessibility due to their ease of use for both staff and patients as compared to MR scanners. The legitimate concern of radiation dose has sparked discussions on the risk vs benefit of CT scanning. It is recognized that newer CT applications, like CCTA and perfusion, will be severely curtailed unless radiation dose is reduced. This paper discusses the various hardware and software techniques developed to reduce radiation dose to patients in CT scanning. The current average effective dose of a CT study is ∼10 mSv, with the implementation of dose reduction techniques discussed herein; it is realistic to expect that the average effective dose may be decreased by 2-3 fold. Copyright © 2010. Published by Elsevier Ireland Ltd.

  7. 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.

  8. 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

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

    PubMed

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

    2014-02-01

    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. 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. 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 attenuator was relatively

  10. 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

  11. Paediatric dose reduction with the introduction of digital fluorography.

    PubMed

    Mooney, R B; McKinstry, J

    2001-01-01

    Fluoroscopy guided examinations in a paediatric X ray department were initially carried out on a unit that used a conventional screen-film combination for spot-films. A new fluoroscopy unit was installed with the facilities of digital fluorography and last image hold. Comparison of equipment performance showed that the dose per image for screen-film and digital fluorography was 3 microGy and 0.4 microGy, respectively. Although the screen-film had superior image quality, the department's radiologist confirmed that digital fluorography provided a diagnostic image. Patient dose measurements showed that introduction of the new unit caused doses to fall by an average of 70%, although fluoroscopy time had not changed significantly. The new unit produced 40% less air kerma during fluoroscopy. The remaining 30% reduction in dose was due to the introduction of digital fluorography and last image hold facilities. It is concluded that the use of digital fluorography can be an effective way of reducing paediatric dose.

  12. Radiation dose reduction in parasinus CT by spectral shaping.

    PubMed

    May, Matthias S; Brand, Michael; Lell, Michael M; Sedlmair, Martin; Allmendinger, Thomas; Uder, Michael; Wuest, Wolfgang

    2017-02-01

    Spectral shaping aims to narrow the X-ray spectrum of clinical CT. The aim of this study was to determine the image quality and the extent of radiation dose reduction that can be achieved by tin prefiltration for parasinus CT. All scans were performed with a third generation dual-source CT scanner. A study protocol was designed using 100 kV tube voltage with tin prefiltration (200 mAs) that provides image noise levels comparable to a low-dose reference protocol using 100 kV without spectral shaping (25 mAs). One hundred consecutive patients were prospectively enrolled and randomly assigned to the study or control group. All patients signed written informed consent. The study protocol was approved by the local Institutional Review Board and applies to the HIPAA. Subjective and objective image quality (attenuation values, image noise, and contrast-to-noise ratio (CNR)) were assessed. Radiation exposure was assessed as volumetric CT dose index, and effective dose was estimated. Mann-Whitney U test was performed for radiation exposure and for image noise comparison. All scans were of diagnostic image quality. Image noise in air, in the retrobulbar fat, and in the eye globe was comparable between both groups (all p > 0.05). CNReye globe/air did not differ significantly between both groups (p = 0.7). Radiation exposure (1.7 vs. 2.1 mGy, p < 0.01) and effective dose (0.055 vs. 0.066 mSv, p < 0.01) were significantly reduced in the study group. Radiation dose can be further reduced by 17% for low-dose parasinus CT by tin prefiltration maintaining diagnostic image quality.

  13. Radiation dose reduction in paediatric coronary computed tomography: assessment of effective dose and image quality.

    PubMed

    Habib Geryes, Bouchra; Calmon, Raphael; Khraiche, Diala; Boddaert, Nathalie; Bonnet, Damien; Raimondi, Francesca

    2016-07-01

    To assess the impact of different protocols on radiation dose and image quality for paediatric coronary computed tomography (cCT). From January-2012 to June-2014, 140 children who underwent cCT on a 64-slice scanner were included. Two consecutive changes in imaging protocols were performed: 1) the use of adaptive statistical iterative reconstruction (ASIR); 2) the optimization of acquisition parameters. Effective dose (ED) was calculated by conversion of the dose-length product. Image quality was assessed as excellent, good or with significant artefacts. Patients were divided in three age groups: 0-4, 5-7 and 8-18 years. The use of ASIR combined to the adjustment of scan settings allowed a reduction in the median ED of 58 %, 82 % and 85 % in 0-4, 5-7 and 8-18 years group, respectively (7.3 ± 1.4 vs 3.1 ± 0.7 mSv, 5.5 ± 1.6 vs 1 ± 1.9 mSv and 5.3 ± 5.0 vs 0.8 ± 2.0 mSv, all p < 0,05). Prospective protocol was used in 51 % of children. The reduction in radiation dose was not associated with reduction in diagnostic image quality as assessed by the frequency of coronary segments with excellent or good image quality (88 %). cCT can be obtained at very low radiation doses in children using ASIR, and prospective acquisition with optimized imaging parameters. • Using ASIR allows 25 % to 41 % reduction in the ED. • Prospective protocol is used up to 51 % of children after premedication. • Low dose is possible using ASIR and optimized prospective paediatric cCT.

  14. Digital radiography in paediatrics: radiation dose considerations and magnitude of possible dose reduction.

    PubMed

    Hufton, A P; Doyle, S M; Carty, H M

    1998-02-01

    The purpose of this study was to evaluate the radiation doses received by paediatric patients examined using a digital radiography unit, and to compare these doses with those received from conventional screen-film systems. In this way, guidelines could be drawn up concerning the magnitude of possible dose reductions achievable using digital radiography. The study was undertaken on approximately 900 patients undergoing abdomen, chest, pelvis and skull examinations. Patients were categorized into the following age groups: 0-1 month, 1-12 months, 1-5 years, 5-10 years and 10-15 years. Approximately half were X-rayed using a Fuji computed radiography system and half using a conventional screen-film system. Entrance surface dose was calculated from the recorded exposure parameters and measured X-ray tube outputs. Dose-area product was recorded directly. Image quality was assessed clinically using criteria recommended by a working group of the Commission of the European Communities. Apart from chest examinations, it was found possible to reduce doses by about 40% on average, by using a computed radiography system instead of a 600 speed screen-film combination. There was no significant difference in the dose for chest examinations. Satisfactory image quality can therefore be achieved by using computed radiography as a 1000 speed system for abdomen, pelvis and skull examinations, and as a 600 speed system for chests. Since very few departments appear to use screen-film systems of speeds greater than 400, then, for most departments, the use of computed radiography would result in dose reductions of at least 60%, or 33% for chests.

  15. 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.

  16. Efficacy, Dose Reduction, and Resistance to High-dose Fluticasone in Patients with Eosinophilic Esophagitis

    PubMed Central

    Butz, Bridget K.; Wen, Ting; Gleich, Gerald J.; Furuta, Glenn T.; Spergel, Jonathan; King, Eileen; Kramer, Robert E.; Collins, Margaret H.; Stucke, Emily; Mangeot, Colleen; Jackson, W. Daniel; O’Gorman, Molly; Abonia, J. Pablo; Pentiuk, Scott; Putnam, Philip E.; Rothenberg, Marc E.

    2014-01-01

    Background & Aims We evaluated the efficacy and safety of high-dose swallowed fluticasone propionate (FP) and dose reduction in patients with eosinophilic esophagitis (EoE) and analyzed esophageal transcriptomes to identify mechanisms. Methods We conducted a randomized, multisite, double-blind, placebo-controlled trial of daily 1760 mcg FP in participants 3–30 years old with active EoE. Twenty-eight participants received FP and 14 received placebo. After 3 months, participants given FP who were in complete remission (CR) received 880 mcg FP daily, and participants in the FP or placebo groups who were not in CR continued or started, respectively, 1760 mcg FP daily for 3 additional months. The primary endpoint was histologic evidence for CR. Secondary endpoints were partial remission (PR), symptoms, compliance, esophageal gene expression, esophageal eosinophil count, and the relationship between clinical features and FP responsiveness. Results After 3 months, 65% of subjects given FP and no subjects given placebo were in CR (P=.0001); 12% of those given FP and 8% of those given placebo were in PR. In the FP group, 73% of subjects remained in CR and 20% were in PR after the daily dose was reduced by 50%. Extending FP therapy in FP-resistant participants did not induce remission. FP decreased heartburn severity (P=.041). Compliance, age, sex, atopic status, or anthropomorphic features were not associated with response to FP. Gene expression patterns in esophageal tissues of FP responders were similar to those of patients without EoE; there was evidence for heterogeneous steroid signaling in subjects that did not respond to FP. Conclusions Daily administration of a high dose of FP induces histologic remission in 65%–77% of patients with EoE after 3 months. A 50% dose reduction remained effective in 73%–93% of patients that initially responded to FP. Nonresponders had evidence of steroid resistance; histologic and molecular markers may predict resistance

  17. Infusion device standardisation and dose error reduction software.

    PubMed

    Iacovides, Ioanna; Blandford, Ann; Cox, Anna; Franklin, Bryony Dean; Lee, Paul; Vincent, Chris J

    In 2004, the National Patient Safety Agency (NPSA) released a safety alert relating to the management and use of infusion devices in England and Wales. The alert called for the standardisation of infusion devices and a consideration of using centralised equipment systems to manage device storage. There has also been growing interest in smart-pump technology, such as dose error reduction software (DERS) as a way to reduce IV medication errors. However, questions remain about the progress that has been made towards infusion device standardisation and the adoption of DERS. In this article, the authors report the results of a survey investigating the extent to which the standardisation of infusion devices has occurred in the last 10 years and centralised equipment libraries are being used in practice, as well as the prevalence of DERS use within the UK. Findings indicate that while reported standardisation levels are high, use of centralised equipment libraries remains low, as does DERS usage.

  18. Infusion device standardisation and dose error reduction software.

    PubMed

    Iacovides, Ioanna; Blandford, Ann; Cox, Anna; Franklin, Bryony Dean; Lee, Paul; Vincent, Christopher J

    2014-07-01

    In 2004, the National Patient Safety Agency (NPSA) released a safety alert relating to the management and use of infusion devices in England and Wales. The alert called for the standardisation of infusion devices and a consideration of using centralised equipment systems to manage device storage. There has also been growing interest in smart-pump technology, such as dose error reduction software (DERS) as a way to reduce IV medication errors. However, questions remain about the progress that has been made towards infusion device standardisation and the adoption of DERS. In this article, the authors report the results of a survey investigating the extent to which the standardisation of infusion devices has occurred in the last 10 years and centralised equipment libraries are being used in practice, as well as the prevalence of DERS use within the UK. Findings indicate that while reported standardisation levels are high, use of centralised equipment libraries remains low, as does DERS usage.

  19. 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.

  20. Pectus excavatum: current imaging techniques and opportunities for dose reduction.

    PubMed

    Sarwar, Zahir U; DeFlorio, Robert; O'Connor, Stephen C

    2014-08-01

    Pectus excavatum (PE) is the most common congenital chest wall deformity in children. It affects 1 in every 300-1000 live births with a male to female ratio of 5:1. Most of the patients present in their first year of life. During the teenage years, patients may have exercise intolerance and psychological strain because of their chest wall deformity. The Nuss and Ravitch procedures are established methods of surgical correction of PE. An index of severity known best as the Haller index, typically evaluated with computed tomography scan, when measuring greater than 3.2 is considered to indicate moderate or severe PE and is a prerequisite for third-party insurance reimbursement for these corrective procedures. This article reviews the clinical features of PE, the role of imaging, and the opportunities for radiation dose reduction.

  1. 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.

  2. Securing safe and informative thoracic CT examinations-Progress of radiation dose reduction techniques.

    PubMed

    Kubo, Takeshi; Ohno, Yoshiharu; Seo, Joon Beom; Yamashiro, Tsuneo; Kalender, Willi A; Lee, Chang Hyun; Lynch, David A; Kauczor, Hans-Ulrich; Hatabu, Hiroto

    2017-01-01

    The increase in the radiation exposure from CT examinations prompted the investigation on the various dose-reduction techniques. Significant dose reduction has been achieved and the level of radiation exposure of thoracic CT is expected to reach the level equivalent to several chest X-ray examinations. With more scanners with advanced dose reduction capability deployed, knowledge on the radiation dose reduction methods has become essential to clinical practice as well as academic research. This article reviews the history of dose reduction techniques, ongoing changes brought by newer technologies and areas of further investigation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Radiation dose reduction in multidetector CT in fracture evaluation.

    PubMed

    Yi, Jung Woo; Park, Hee Jin; Lee, So Yeon; Rho, Myung Ho; Hong, Hyun Pyo; Choi, Yoon Jung; Kim, Mi Sung

    2017-08-01

    To evaluate whether multidetector CT with low-dose radiation (low-dose CT) of joints can be useful when evaluating fractures. Our study included CT scans of 398 patients, 103 shoulder cases, 109 wrist cases, 98 pelvis cases and 88 ankle cases. There were 191 females and 207 males. The low-dose CTs were performed using identical voltage and parameters with the exception of decreased (half of standard dose) tube current. Low-dose and standard-dose images were compared with regards to objective image quality, subjective evaluation of image quality and diagnostic performance for the fractures. There was no significant difference of image noise between standard-dose CT and low-dose CT in every joint (p > 0.05). Each mean value of subjective score did not show significant difference according to the dosage of the CT scan. There were no statistically significant differences in the sensitivity (96-100%), specificity (95.2-100%) or accuracy (97.9-100%) between standard-dose CT and low-dose CT (p values, 0.1336-1.000). The evaluation of extremities for fractures using low-dose CT can reduce radiation exposure by about 50% compared with standard-dose CT without affecting image quality or diagnostic performance. Advances in knowledge: Low-dose CT of the extremities (shoulder, pelvis, ankle and wrist) can reduce radiation dose by about 50% compared with standard-dose CT and does not significantly affect image quality or diagnostic performance in fracture detection.

  4. [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%.

  5. Optimization of radiation dose reduction in cardiac computed tomographic angiography.

    PubMed

    Entrikin, Daniel W; Leipsic, Jonathon A; Carr, J Jeffrey

    2011-01-01

    Cardiac computed tomographic angiography (CCTA) has evolved at an unprecedented pace over the past decade, during which time it has proven to be an accurate and effective tool for imaging of the heart in a growing list of clinical applications. However, the rapid growth in the use of CT imaging in general has prompted appropriate concerns regarding increasing medical radiation exposure to patients, particularly with regard to potential long-term risks of radiation-induced malignancy on both individual and population levels. As with all medical imaging modalities, imaging the heart with CCTA should be performed in a manner that achieves diagnostic image quality while maintaining patient radiation exposure as low as reasonably achievable (As Low As Reasonably Achievable [ALARA] principle). The goal of this article is to provide the reader with a wide-ranging review of both primary and secondary techniques that are currently available to minimize patient radiation exposure. Some of the techniques described in this article are universal, whereas others may be scanner specific. By gaining a thorough understanding of the various tools and methodologies employed for reduction of radiation exposure, the cardiac imager should be able to formulate CCTA protocols appropriate for their equipment and their clinical applications, in a manner that optimally preserves diagnostic image quality and minimizes patient radiation dose.

  6. 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.

  7. Radiation dose reduction in perfusion CT imaging of the brain: A review of the literature.

    PubMed

    Othman, Ahmed E; Afat, Saif; Brockmann, Marc A; Nikoubashman, Omid; Brockmann, Carolin; Nikolaou, Konstantin; Wiesmann, Martin

    2016-02-01

    Perfusion CT (PCT) of the brain is widely used in the settings of acute ischemic stroke and vasospasm monitoring. The high radiation dose associated with PCT is a central topic and has been a focus of interest for many researchers. Many studies have examined the effect of radiation dose reduction in PCT using different approaches. Reduction of tube current and tube voltage can be efficient and lead to a remarkable reduction of effective radiation dose while preserving acceptable image quality. The use of novel noise reduction techniques such as iterative reconstruction or spatiotemporal smoothing can produce sufficient image quality from low-dose perfusion protocols. Reduction of sampling frequency of perfusion images has only little potential to reduce radiation dose. In the present article we aimed to summarize the available data on radiation dose reduction in PCT imaging of the brain. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  8. Oral anticancer drugs: how limited dosing options and dose reductions may affect outcomes in comparative trials and efficacy in patients.

    PubMed

    Prasad, Vinay; Massey, Paul R; Fojo, Tito

    2014-05-20

    Historically, cancer medicine has avoided the problem of unequal dosing by comparing maximum-tolerated doses of intravenous regimens with proportionate dose reductions for toxicity. However, in recent years, with the development of numerous oral anticancer agents, dosing options are arbitrarily and increasingly limited by the size of pills. We contend that an underappreciated consequence of pill size is unequal dosing in comparative clinical trials and that this can have an impact on outcomes. We discuss how comparative effectiveness trials can be unbalanced and how the use of doses that are not sustainable might affect outcomes, especially marginal ones. We further argue that because of their poor tolerability and their limited dosing options, which often result in large dose adjustments in response to toxicity, the real-world clinical effectiveness of oral anticancer agents may be diminished and may not emulate results achieved in registration trials.

  9. Oral Anticancer Drugs: How Limited Dosing Options and Dose Reductions May Affect Outcomes in Comparative Trials and Efficacy in Patients

    PubMed Central

    Prasad, Vinay; Massey, Paul R.; Fojo, Tito

    2014-01-01

    Historically, cancer medicine has avoided the problem of unequal dosing by comparing maximum-tolerated doses of intravenous regimens with proportionate dose reductions for toxicity. However, in recent years, with the development of numerous oral anticancer agents, dosing options are arbitrarily and increasingly limited by the size of pills. We contend that an underappreciated consequence of pill size is unequal dosing in comparative clinical trials and that this can have an impact on outcomes. We discuss how comparative effectiveness trials can be unbalanced and how the use of doses that are not sustainable might affect outcomes, especially marginal ones. We further argue that because of their poor tolerability and their limited dosing options, which often result in large dose adjustments in response to toxicity, the real-world clinical effectiveness of oral anticancer agents may be diminished and may not emulate results achieved in registration trials. PMID:24711558

  10. 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.

  11. 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.

  12. Radiation dose during CT-guided percutaneous cryoablation of renal tumors: Effect of a dose reduction protocol.

    PubMed

    Levesque, Vincent M; Shyn, Paul B; Tuncali, Kemal; Tatli, Servet; Nawfel, Richard D; Olubiyi, Olutayo; Silverman, Stuart G

    2015-11-01

    To estimate and compare the radiation dose using a standard protocol and that of a dose reduction protocol in patients undergoing CT-guided percutaneous cryoablation of renal tumors. An IRB-approved, HIPAA-compliant retrospective study of 97 CT-guided cryoablation procedures to treat a solitary renal tumor in each of 97 patients (64 M, 33 F; range 31-84 yrs) was performed. Fifty patients were treated using a standard dose protocol (kVp=120, mean mAs=180, monitoring scans every 3 min during freezes), and an additional 47 patients were treated using a dose reduction protocol (kVp=100, mean mAs=100, monitoring scans less frequently than every 3 min during freezes). Multiple Wilcoxon Mann-Whitney (rank-sum) tests were used to compare dose-length product (DLP) between the two groups. Fisher's exact test was used to compare technique effectiveness at 12 months post ablation between the two groups. Median DLP for the standard protocol group was 4833.5 mGy*cm (range, 1667-8267 mGy*cm); median DLP for the dose reduction group was 2648 mGy*cm (range, 850-7169 mGy*cm), significantly less than that of the standard protocol group (p<0.01). The technique effectiveness for the dose reduction group was not significantly different from that of the standard protocol group at 12 month follow up (p=0.434). The radiation dose during percutaneous CT-guided cryoablation of renal tumors was substantial in both the standard and the dose reduction groups; however, it was significantly lower with the protocol change that reduced dose parameters and decreased the number of CT scans. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Edematogenic activity of scorpion venoms from the Buthidae family and the role of platelet-activating factor and nitric oxide in paw edema induced by Tityus venoms.

    PubMed

    Severino, D N; Pereira, R L; Knysak, I; Cândido, D M; Kwasniewski, F H

    2009-02-01

    We compared the edematogenic activity of venoms of scorpions from the Buthidae family, Tityus bahiensis (Tbv), Tityus serrulatus (Tsv) and Rhopalurus rochai (Rrv). Three doses (20, 40 and 80 microg/kg sc) of each venom were administrated in hind paw of mice and edema was measured from 5 min to 24 h. Tbv and Tsv both induced edema of rapid onset (135% of increase at 15 min); Rrv induced only a mild edema (40% of increase). We then investigated the involvement of platelet-activating factor (PAF) and endogenous nitric oxide (NO) in Tbv and Tsv-induced paw edema. Pretreatment of mice with a PAF antagonist (WEB-2170) inhibited Tsv but not Tbv-induced edema. Pretreatment with a non selective inhibitor of NO-synthases (L: -NAME) inhibited or increased the edema depending on the dose and the time the edema was measured. In conclusion, the venoms from Tityus are stronger inducers of edema than the venom from the Rhopalurus scorpion. The venoms of Tityus species are similar in potency and time-course edema development. PAF is involved in the edema induced only by Tsv.

  14. Dose reduction potential of iterative reconstruction algorithms in neck CTA-a simulation study.

    PubMed

    Ellmann, Stephan; Kammerer, Ferdinand; Allmendinger, Thomas; Brand, Michael; Janka, Rolf; Hammon, Matthias; Lell, Michael M; Uder, Michael; Kramer, Manuel

    2016-10-01

    This study aimed to determine the degree of radiation dose reduction in neck CT angiography (CTA) achievable with Sinogram-affirmed iterative reconstruction (SAFIRE) algorithms. 10 consecutive patients scheduled for neck CTA were included in this study. CTA images of the external carotid arteries either were reconstructed with filtered back projection (FBP) at full radiation dose level or underwent simulated dose reduction by proprietary reconstruction software. The dose-reduced images were reconstructed using either SAFIRE 3 or SAFIRE 5 and compared with full-dose FBP images in terms of vessel definition. 5 observers performed a total of 3000 pairwise comparisons. SAFIRE allowed substantial radiation dose reductions in neck CTA while maintaining vessel definition. The possible levels of radiation dose reduction ranged from approximately 34 to approximately 90% and depended on the SAFIRE algorithm strength and the size of the vessel of interest. In general, larger vessels permitted higher degrees of radiation dose reduction, especially with higher SAFIRE strength levels. With small vessels, the superiority of SAFIRE 5 over SAFIRE 3 was lost. Neck CTA can be performed with substantially less radiation dose when SAFIRE is applied. The exact degree of radiation dose reduction should be adapted to the clinical question, in particular to the smallest vessel needing excellent definition.

  15. 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.

  16. The benefit of accounting for DQE variations in simulated dose reduction of digital radiographic systems.

    PubMed

    Svalkvist, Angelica; Båth, Magnus

    2010-01-01

    Adding noise to clinical radiographs to simulate dose reduction can be used to investigate the relationship between dose level and clinical image quality without exposing patients to additional radiation. The purpose of the present paper was to examine the benefits of using a method that accounts for detective quantum efficiency (DQE) variations that may occur in different dose ranges in the simulated dose reduction process. A method initially intended for simulated dose reduction in tomosynthesis was applied to extremely low-dose posterioanterior radiographs of an anthropomorphic chest phantom, selected from a group of projection images included in a tomosynthesis examination and compared with a previous method that do not account for DQE variations. A comparison of images simulated to be collected at a lower dose level (73 % of the original dose level) and images actually collected at this lower dose level revealed that the error in the integrated normalised noise power spectrum was smaller than 4 % for the method that accounts for DQE variations in the simulated dose reduction, whereas the error was larger than 20 % for the previous method. This indicates that an increased validity in dose reduction simulation of digital radiographic systems is obtained with a method accounting for DQE variations.

  17. 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.

  18. Radiation dose reduction efficiency of buildings after the accident at the Fukushima Daiichi Nuclear Power Station.

    PubMed

    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.

  19. 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

  20. 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.…

  1. 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.…

  2. 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.

  3. Radiation dose reduction in chest CT--review of available options.

    PubMed

    Kubo, Takeshi; Ohno, Yoshiharu; Kauczor, Hans Ulrich; Hatabu, Hiroto

    2014-10-01

    Computed tomography currently accounts for the majority of radiation exposure related to medical imaging. Although technological improvement of CT scanners has reduced the radiation dose of individual examinations, the benefit was overshadowed by the rapid increase in the number of CT examinations. Radiation exposure from CT examination should be kept as low as reasonably possible for patient safety. Measures to avoid inappropriate CT examinations are needed. Principles and information on radiation dose reduction in chest CT are reviewed in this article. The reduction of tube current and tube potential are the mainstays of dose reduction methods. Study results indicate that routine protocols with reduced tube current are feasible with diagnostic results comparable to conventional standard dose protocols. Tube current adjustment is facilitated by the advent of automatic tube current modulation systems by setting the appropriate image quality level for the purpose of the examination. Tube potential reduction is an effective method for CT pulmonary angiography. Tube potential reduction often requires higher tube current for satisfactory image quality, but may still contribute to significant radiation dose reduction. Use of lower tube potential also has considerable advantage for smaller patients. Improvement in image production, especially the introduction of iterative reconstruction methods, is expected to lower radiation dose significantly. Radiation dose reduction in CT is a multifaceted issue. Understanding these aspects leads to an optimal solution for various indications of chest CT. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Ultra-Low-Dose CT of the Thorax Using Iterative Reconstruction: Evaluation of Image Quality and Radiation Dose Reduction.

    PubMed

    Kim, Yookyung; Kim, Yoon Kyung; Lee, Bo Eun; Lee, Seok Jeong; Ryu, Yon Ju; Lee, Jin Hwa; Chang, Jung Hyun

    2015-06-01

    The purpose of this study is to assess the image quality and radiation dose reduction of ultra-low-dose CT using sinogram-affirmed iterative reconstruction (SAFIRE). This prospective study enrolled 25 patients who underwent three consecutive unenhanced CT scans including low-dose CT (120 kVp and 30 mAs) and two ultra-low-dose CT protocols (protocol A, 100 kVp and 20 mAs; protocol B, 80 kVp and 30 mAs) with image reconstruction using SAFIRE. The image quality and radiation dose reduction were assessed. The mean (± SD) effective radiation dose was 1.06 ± 0.11, 0.44 ± 0.05, and 0.31 ± 0.03 mSv for low-dose CT, ultra-low-dose CT protocol A, and ultra-low-dose CT protocol B, respectively. Overall image quality was determined as diagnostic in 100% of low-dose CT scans, 96% of ultra-low-dose CT protocol A scans, and 88% of ultra-low-dose CT protocol B scans. All patients with nondiagnostic quality images had a body mass index (weight in kilograms divided by the square of height in meters) greater than 25. There was no statistically significant difference in detection frequencies of 14 lesion types among the three CT protocols, but pulmonary emphysema was detected in fewer patients (3/25) in ultra-low-dose CT protocol B scans compared with ultra-low-dose CT protocol A scans (5/25) or low-dose CT scans (6/25). We measured the longest dimensions of 33 small solid nodules (3.8-12.4 mm in long diameter) and found no statistically significant difference in the values afforded by the three CT protocols (p = 0.135). Iterative reconstruction allows ultra-low-dose CT and affords acceptable image quality, allowing size measurements of solid pulmonary nodules to be made.

  5. Conditioned placebo dose reduction: a new treatment in attention-deficit hyperactivity disorder?

    PubMed

    Sandler, Adrian D; Glesne, Corrine E; Bodfish, James W

    2010-06-01

    This study examined if pairing a placebo with stimulant medication produces a placebo response that allows children with attention-deficit hyperactivity disorder (ADHD) to be maintained on a lower dose of stimulant medication. The primary aim was to determine the efficacy, side effects, and acceptability of a novel conditioned placebo dose reduction procedure. Participants included 99 children ages 6 to 12 years with ADHD. After an initial double-blind dose finding to identify optimal dose of mixed amphetamine salts, subjects were randomly assigned to 1 of 3 treatments of 8-week duration: (a) conditioned placebo dose reduction condition (50% reduced dose/placebo [RD/P]) or (b) a dose reduction only condition (RD) or (c) a no reduction condition (full dose). The innovative conditioned placebo dose reduction procedure involved daily pairing of mixed amphetamine salts dose with a visually distinctive placebo capsule administered in open label, with full disclosure of placebo use to subjects and parents. Seventy children completed the study. There were no differences in subject retention among the 3 groups. Most subjects in the RD/P group remained stable during the treatment phase, whereas most in the RD group deteriorated. There was no difference in control of ADHD symptoms between the RD/P group and the full dose group, and both RD/P and full dose groups showed better ADHD control than the RD group. Treatment emergent side effects were lowest in the RD/P group. Pairing placebos with stimulant medication elicits a placebo response that allows children with ADHD to be effectively treated on 50% of their optimal stimulant dose.

  6. 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.

  7. Multidetector CT in children: current concepts and dose reduction strategies

    PubMed Central

    van Dam, Ingrid M.; van der Molen, Aart J.

    2010-01-01

    The recent technical development of multidetector CT (MDCT) has contributed to a substantial increase in its diagnostic applications and accuracy in children. A major drawback of MDCT is the use of ionising radiation with the risk of inducing secondary cancer. Therefore, justification and optimisation of paediatric MDCT is of great importance in order to minimise these risks (“as low as reasonably achievable” principle). This review will focus on all technical and non-technical aspects relevant for paediatric MDCT optimisation and includes guidelines for radiation dose level-based CT protocols. PMID:20535463

  8. Multidetector CT in children: current concepts and dose reduction strategies.

    PubMed

    Nievelstein, Rutger A J; van Dam, Ingrid M; van der Molen, Aart J

    2010-08-01

    The recent technical development of multidetector CT (MDCT) has contributed to a substantial increase in its diagnostic applications and accuracy in children. A major drawback of MDCT is the use of ionising radiation with the risk of inducing secondary cancer. Therefore, justification and optimisation of paediatric MDCT is of great importance in order to minimise these risks ("as low as reasonably achievable" principle). This review will focus on all technical and non-technical aspects relevant for paediatric MDCT optimisation and includes guidelines for radiation dose level-based CT protocols.

  9. Results of comparative assessment of US and Foreign Nuclear Power Plant dose experience and dose reduction programs

    SciTech Connect

    Baum, J.W.; Horan, J.R.; Dionne, B.J.

    1984-01-01

    Based on data evaluated to date it is clear that US plants have higher collective dose equivalents per reactor and per MW-y generated than most other countries. Factors which contribute to low doses include: (1) minimization of cobalt in primary system components exposed to water, (2) careful control of primary system oxygen and pH, (3) good primary system water purity to minimize corrosion product formation, (4) careful plant design, layout and component segration and shielding, (5) management interest and commitment, (6) minimum number of workers and in-depth worker training, (7) use of special tools, and (8) plant standardization. It should be pointed out that reductions in exposure are more difficult and costly in plants already built and operating. The cost-effectiveness of dose reduction efforts at US plants should be carefully evaluated before recommendations are made concerning existing plants.

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

    PubMed

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

    2016-06-01

    This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. 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. 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%. 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 transformation. NNPS, PS, and local noise

  11. 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).

  12. Quality initiatives: CT radiation dose reduction: how to implement change without sacrificing diagnostic quality.

    PubMed

    Tamm, Eric P; Rong, X John; Cody, Dianna D; Ernst, Randy D; Fitzgerald, Nancy E; Kundra, Vikas

    2011-01-01

    The risks and benefits of using computed tomography (CT) as opposed to another imaging modality to accomplish a particular clinical goal should be weighed carefully. To accurately assess radiation risks and keep radiation doses as low as reasonably achievable, radiologists must be knowledgeable about the doses delivered during various types of CT studies performed at their institutions. The authors of this article propose a process improvement approach that includes the estimation of effective radiation dose levels, formulation of dose reduction goals, modification of acquisition protocols, assessment of effects on image quality, and implementation of changes necessary to ensure quality. A first step toward developing informed radiation dose reduction goals is to become familiar with the radiation dose values and radiation-associated health risks reported in the literature. Next, to determine the baseline dose values for a CT study at a particular institution, dose data can be collected from the CT scanners, interpreted, tabulated, and graphed. CT protocols can be modified to reduce overall effective dose by using techniques such as automated exposure control and iterative reconstruction, as well as by decreasing the number of scanning phases, increasing the section thickness, and adjusting the peak voltage (kVp setting), tube current-time product (milliampere-seconds), and pitch. Last, PDSA (plan, do, study, act) cycles can be established to detect and minimize negative effects of dose reduction methods on image quality.

  13. Post-LASIK edema-induced keratopathy (PLEK), a new name based on pathophysiology of the condition

    PubMed Central

    Galvis, Virgilio; Tello, Alejandro; Revelo, Mario Leandro; Valarezo, Paul

    2012-01-01

    A 33-year-old man who underwent uneventful laser in situ keratomileusis (LASIK) developed pressure-induced stromal edema resulting in an interface haze in both eyes and a pocket of fluid under the flap of the right eye 10 days after surgery, while receiving topical fluorometholone. Intraocular pressure by applanation tonometry was 16 mm Hg in his right eye (erroneous result due to the fluid in the interface) and 34 mm Hg in his left eye. After discontinuation of steroids and addition of ocular hypotensive medication, interface fluid collection disappeared in his right eye. Visual acuity improved and haze diminished in both eyes. This case illustrates that in the same patient a post-LASIK edema induced syndrome may be present with or without fluid in the interface, suggesting that both clinical pictures could be manifestations of a broad spectrum of the same condition. We suggest a new name for this non-inflammatory disorder: post-LASIK edema-induced keratopathy (PLEK). PMID:23112265

  14. Post-LASIK edema-induced keratopathy (PLEK), a new name based on pathophysiology of the condition.

    PubMed

    Galvis, Virgilio; Tello, Alejandro; Revelo, Mario Leandro; Valarezo, Paul

    2012-10-30

    A 33-year-old man who underwent uneventful laser in situ keratomileusis (LASIK) developed pressure-induced stromal edema resulting in an interface haze in both eyes and a pocket of fluid under the flap of the right eye 10 days after surgery, while receiving topical fluorometholone. Intraocular pressure by applanation tonometry was 16 mm Hg in his right eye (erroneous result due to the fluid in the interface) and 34 mm Hg in his left eye. After discontinuation of steroids and addition of ocular hypotensive medication, interface fluid collection disappeared in his right eye. Visual acuity improved and haze diminished in both eyes. This case illustrates that in the same patient a post-LASIK edema induced syndrome may be present with or without fluid in the interface, suggesting that both clinical pictures could be manifestations of a broad spectrum of the same condition. We suggest a new name for this non-inflammatory disorder: post-LASIK edema-induced keratopathy (PLEK).

  15. Generalized pustular psoriasis induced by systemic steroid dose reduction.

    PubMed

    Westphal, Danielle Cristine; Schettini, Antonio Pedro Mendes; Souza, Petra Pereira de; Castiel, Jessica; Chirano, Carlos Alberto; Santos, Mônica

    2016-01-01

    Generalized pustular psoriasis, or psoriasis of von Zumbusch, is an acute and severe clinical form of psoriasis, which usually occurs in patients with psoriasis undergoing aggravating factors. In this work, we report the case of a female patient, 70 years old, who developed generalized pustular psoriasis symptoms while reducing the dose of oral corticosteroids, improperly introduced for the treatment of alleged acute generalized exanthematous pustulosis. The differential diagnosis of generalized pustular psoriasis should be made with other pustular dermatoses, such as subcorneal pustulosis, IgA pemphigus and especially with acute generalized exanthematous pustulosis. Personal history of psoriasis and histopathological findings with psoriasiform changes and subcorneal pustule favored the diagnosis. She was treated with acitretin 30 mg / day, progressing to complete regression of the lesions.

  16. Generalized pustular psoriasis induced by systemic steroid dose reduction*

    PubMed Central

    Westphal, Danielle Cristine; Schettini, Antonio Pedro Mendes; de Souza, Petra Pereira; Castiel, Jessica; Chirano, Carlos Alberto; Santos, Mônica

    2016-01-01

    Generalized pustular psoriasis, or psoriasis of von Zumbusch, is an acute and severe clinical form of psoriasis, which usually occurs in patients with psoriasis undergoing aggravating factors. In this work, we report the case of a female patient, 70 years old, who developed generalized pustular psoriasis symptoms while reducing the dose of oral corticosteroids, improperly introduced for the treatment of alleged acute generalized exanthematous pustulosis. The differential diagnosis of generalized pustular psoriasis should be made with other pustular dermatoses, such as subcorneal pustulosis, IgA pemphigus and especially with acute generalized exanthematous pustulosis. Personal history of psoriasis and histopathological findings with psoriasiform changes and subcorneal pustule favored the diagnosis. She was treated with acitretin 30 mg / day, progressing to complete regression of the lesions. PMID:27828647

  17. Dose reduction and cost-benefit analysis at Japan`s Tokai No. 2 Plant

    SciTech Connect

    Humamoto, Hisao; Suzuki, Seishiro; Taniguchi, Kazufumi

    1995-03-01

    In the Tokai No. 2 power plant of the Japan Atomic Power Company, about 80% of the annual dose equivalent is received during periodic maintenance outages. A project group for dose reduction was organized at the company`s headquarters in 1986; in 1988, they proposed a five-year program to reduce by half the collective dose of 4 person-Sv per normal outage work. To achieve the target dose value, some dose-reduction measures were undertaken, namely, permanent radiation shielding, decontamination, automatic, operating machines, and ALARA organization. As the result, the collective dose from normal outage work was 1.6 person-Sv in 1992, which was less than the initial target value.

  18. Inter- and Intrafractional Movement-Induced Dose Reduction of Prostate Target Volume in Proton Beam Treatment

    SciTech Connect

    Yoon, Myonggeun; Kim, Dongwook; Shin, Dong Ho; Park, Sung Yong Lee, Se Byeong; Kim, Dae Yong; Kim, Joo Young; Pyo, Hong Ryull; Cho, Kwan Ho

    2008-07-15

    Purpose: To quantify proton radiotherapy dose reduction in the prostate target volume because of the three-dimensional movement of the prostate based on an analysis of dose-volume histograms (DVHs). Methods and Materials: Twelve prostate cancer patients underwent scanning in supine position, and a target contour was delineated for each using a proton treatment planning system. To simulate target movement, the contour was displaced from 3 to 15 mm in 3-mm intervals in the superior-to-inferior (SI), inferior-to-superior (IS), anterior-to-posterior (AP), posterior-to-anterior (PA), and left-to-right (LR) directions. Results: For both intra- and interfractional movements, the average coverage index and conformity index of the target were reduced in all directions. For interfractional movements, the magnitude of dose reduction was greater in the LR direction than in the AP, PA, SI. and IS directions. Although the reduction of target dose was proportional to the magnitude of intrafractional movement in all directions, a proportionality between dose reduction and the magnitude of interfractional target movement was clear only in the LR direction. Like the coverage index and conformity index, the equivalent uniform dose and homogeneity index showed similar reductions for both types of target movements. Conclusions: Small target movements can significantly reduce target proton radiotherapy dose during treatment of prostate cancer patients. Attention should be given to interfractional target movement along the longitudinal direction, as image-guided radiotherapy may be ineffective if margins are not sufficient.

  19. 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

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

    PubMed

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

    2015-09-01

    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. 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. 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. RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field.

  1. Patients with Fabry disease after enzyme replacement therapy dose reduction versus treatment switch.

    PubMed

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

    2014-04-01

    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 m(2) (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.

  2. Functional depletion of capsaicin-sensitive primary afferent fibers attenuates rat pain-related behaviors and paw edema induced by the venom of scorpion Buthus martensi Karch.

    PubMed

    Bai, Zhan-Tao; Liu, Tong; Pang, Xue-Yan; Jiang, Feng; Cheng, Ming; Ji, Yong-Hua

    2008-10-01

    The role of capsaicin-sensitive primary afferent fibers in rat pain-related behaviors and paw edema induced by scorpion Buthus martensi Karch (BmK) venom was investigated in this study. It was found that functional depletion of capsaicin-sensitive primary afferent fibers with a single systemic injection of resiniferatoxin (RTX) dramatically decreased spontaneous nociceptive behaviors, prevented the development of primary mechanical and thermal hyperalgesia as well as mirror-image mechanical hyperalgesia. RTX treatment significantly attenuated BmK venom-induced c-Fos expression in all laminaes of bilateral L4-L5 lumbar spinal cord, especially in superficial laminaes. Moreover, RTX treatment markedly reduced the early paw edema induced by BmK venom. Thus, the results indicate that capsaicin-sensitive primary afferent fibers play a critical role in various pain-related behaviors and paw edema induced by BmK venom in rats.

  3. A Radiation Dose Reduction Technology to Improve Patient Safety During Cardiac Catheterization Interventions.

    PubMed

    Bracken, John A; Mauti, Maria; Kim, Michael S; Messenger, John C; Carroll, John D

    2015-10-01

    A novel radiation dose reduction technology was evaluated in a cardiac catheterization laboratory during routine clinical care to determine if it could reduce radiation dose to patients undergoing coronary angiography and percutaneous coronary intervention. These results were compared to patients undergoing similar procedures in a cardiac catheterization laboratory without this technology. There is a safety priority in clinical care to reduce X-ray radiation dose to patients in order to lower the risk of deterministic and stochastic effects. Dose reduction technologies must be verified in clinical settings to prove if they reduce X-ray radiation dose and to what extent. Radiation dose data and procedure characteristics of 268 consecutive patients were collected and analyzed from a cardiac catheterization laboratory with dose reduction technology installed (referred to as Lab A, n = 135) and from a cardiac catheterization laboratory without this technology (referred as Lab B, n = 133). For diagnostic procedures, the median total dose-area product in Lab A was reduced by 46% (P < 0.0001) compared to Lab B, with no differences in terms of body mass index (P = 0.180), total fluoroscopy times (P = 1), number of acquired images (P = 0.920), and contrast medium (P = 0.660). For interventional procedures, the median total dose-area product in Lab A was reduced by 34% (P = 0.015) compared to Lab B, with no differences in terms of body mass index (P = 0.665), total fluoroscopy times (P = 0.765), number of acquired images (P = 0.923), and contrast medium (P = 0.969). This new dose reduction technology significantly reduces X-ray radiation dose without affecting fluoroscopy time, number of images, and contrast medium used during diagnostic and interventional coronary procedures. © 2015, Wiley Periodicals, Inc.

  4. Simulated 50 % radiation dose reduction in coronary CT angiography using adaptive iterative dose reduction in three-dimensions (AIDR3D).

    PubMed

    Chen, Marcus Y; Steigner, Michael L; Leung, Steve W; Kumamaru, Kanako K; Schultz, Kurt; Mather, Richard T; Arai, Andrew E; Rybicki, Frank J

    2013-06-01

    To compare the image quality of coronary CT angiography (CTA) studies between standard filtered back projection (FBP) and adaptive iterative dose reduction in three-dimensions (AIDR3D) reconstruction using CT noise additional software to simulate reduced radiation exposure. Images from 93 consecutive clinical coronary CTA studies were processed utilizing standard FBP, FBP with 50% simulated dose reduction (FBP50%), and AIDR3D with simulated 50% dose reduction (AIDR50%). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured within 5 regions-of-interest, and image quality for each reconstruction strategy was assessed by two independent readers using a 4-point scale. Compared to FBP, the SNR measured from the AIDR50% images was similar or higher (airway: 38.3 ± 12.7 vs. 38.5 ± 14.5, p = 0.81, fat: 5.5 ± 1.9 vs. 5.4 ± 2.0, p = 0.20, muscle: 3.2 ± 1.2 vs. 3.1 ± 1.3, p = 0.38, aorta: 22.6 ± 9.4 vs. 20.2 ± 9.7, p < 0.0001, liver: 2.7 ± 1.0 vs. 2.3 ± 1.1, p < 0.0001), while the SNR of the FBP50 % images were all lower (p values < 0.0001). The CNR measured from AIDR50% images was also higher than that from the FBP images for the aorta relative to muscle (20.5 ± 9.0 vs. 18.3 ± 9.2, p < 0.0001). The interobserver agreement in the image quality score was excellent (κ = 0.82). The quality score was significantly higher for the AIDR50% images compared to the FBP images (3.6 ± 0.6 vs. 3.3 ± 0.7, p = 0.004). Simulated radiation dose reduction applied to clinical coronary CTA images suggests that a 50% reduction in radiation dose can be achieved with adaptive iterative dose reduction software with image quality that is at least comparable to images acquired at standard radiation exposure and reconstructed with filtered back projection.

  5. Effect of dose reduction on the detection of mammographic lesions: A mathematical observer model analysis

    SciTech Connect

    Chawla, Amarpreet S.; Samei, Ehsan; Saunders, Robert; Abbey, Craig; Delong, David

    2007-08-15

    The effect of reduction in dose levels normally used in mammographic screening procedures on the detection of breast lesions were analyzed. Four types of breast lesions were simulated and inserted into clinically-acquired digital mammograms. Dose reduction by 50% and 75% of the original clinically-relevant exposure levels were simulated by adding corresponding simulated noise into the original mammograms. The mammograms were converted into luminance values corresponding to those displayed on a clinical soft-copy display station and subsequently analyzed by Laguerre-Gauss and Gabor channelized Hotelling observer models for differences in detectability performance with reduction in radiation dose. Performance was measured under a signal known exactly but variable detection task paradigm in terms of receiver operating characteristics (ROC) curves and area under the ROC curves. The results suggested that luminance mapping of digital mammograms affects performance of model observers. Reduction in dose levels by 50% lowered the detectability of masses with borderline statistical significance. Dose reduction did not have a statistically significant effect on detection of microcalcifications. The model results indicate that there is room for optimization of dose level in mammographic screening procedures.

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  7. 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.

  8. SU-E-T-802: Verification of Implanted Cardiac Pacemaker Doses in Intensity-Modulated Radiation Therapy: Dose Prediction Accuracy and Reduction Effect of a Lead Sheet

    SciTech Connect

    Lee, J; Chung, J

    2015-06-15

    Purpose: To verify delivered doses on the implanted cardiac pacemaker, predicted doses with and without dose reduction method were verified using the MOSFET detectors in terms of beam delivery and dose calculation techniques in intensity-modulated radiation therapy (IMRT). Methods: The pacemaker doses for a patient with a tongue cancer were predicted according to the beam delivery methods [step-and-shoot (SS) and sliding window (SW)], intensity levels for dose optimization, and dose calculation algorithms. Dosimetric effects on the pacemaker were calculated three dose engines: pencil-beam convolution (PBC), analytical anisotropic algorithm (AAA), and Acuros-XB. A lead shield of 2 mm thickness was designed for minimizing irradiated doses to the pacemaker. Dose variations affected by the heterogeneous material properties of the pacemaker and effectiveness of the lead shield were predicted by the Acuros-XB. Dose prediction accuracy and the feasibility of the dose reduction strategy were verified based on the measured skin doses right above the pacemaker using mosfet detectors during the radiation treatment. Results: The Acuros-XB showed underestimated skin doses and overestimated doses by the lead-shield effect, even though the lower dose disagreement was observed. It led to improved dose prediction with higher intensity level of dose optimization in IMRT. The dedicated tertiary lead sheet effectively achieved reduction of pacemaker dose up to 60%. Conclusion: The current SS technique could deliver lower scattered doses than recommendation criteria, however, use of the lead sheet contributed to reduce scattered doses.Thin lead plate can be a useful tertiary shielder and it could not acuse malfunction or electrical damage of the implanted pacemaker in IMRT. It is required to estimate more accurate scattered doses of the patient with medical device to design proper dose reduction strategy.

  9. Breast dose reduction with organ-based, wide-angle tube current modulated CT.

    PubMed

    Fu, Wanyi; Sturgeon, Gregory M; Agasthya, Greeshma; Segars, William Paul; Kapadia, Anuj J; Samei, Ehsan

    2017-07-01

    This study aimed to estimate the organ dose reduction potential for organ-dose-based tube current modulated (ODM) thoracic computed tomography (CT) with a wide dose reduction arc. Twenty-one computational anthropomorphic phantoms (XCAT) were used to create a virtual patient population with clinical anatomic variations. The phantoms were created based on patient images with normal anatomy (age range: 27 to 66 years, weight range: 52.0 to 105.8 kg). For each phantom, two breast tissue compositions were simulated: [Formula: see text] and [Formula: see text] (glandular-to-adipose ratio). A validated Monte Carlo program (PENELOPE, Universitat de Barcelona, Spain) was used to estimate the organ dose for standard tube current modulation (TCM) (SmartmA, GE Healthcare) and ODM (GE Healthcare) for a commercial CT scanner (Revolution, GE Healthcare) using a typical clinical thoracic CT protocol. Both organ dose and [Formula: see text]-to-organ dose conversion coefficients ([Formula: see text] factors) were compared between TCM and ODM. ODM significantly reduced all radiosensitive organ doses ([Formula: see text]). The breast dose was reduced by [Formula: see text]. For [Formula: see text] factors, organs in the anterior region (e.g., thyroid and stomach) exhibited substantial decreases, and the medial, distributed, and posterior region saw either an increase of less than 5% or no significant change. ODM significantly reduced organ doses especially for radiosensitive superficial anterior organs such as the breasts.

  10. ACR White Paper-Based Comprehensive Dose Reduction Initiative Is Associated With a Reversal of the Upward Trend in Radiation Dose for Chest CT.

    PubMed

    Rawat, Udit; Cohen, Stuart L; Levsky, Jeffrey M; Haramati, Linda B

    2015-12-01

    In 2010, the authors' department implemented a comprehensive dose reduction strategy based on the ACR white paper on radiation dose in medicine. The aim of this study was to evaluate the effectiveness of the dose reduction program. In total, 1,234 adult chest CT scans from 2007 to 2012 were analyzed retrospectively, with institutional review board approval and a waiver of the requirement for informed consent. The primary outcome was effective dose in millisieverts during the three-year periods before (2007-2009) and after (2010-2012) dose reduction implementation. Dose trends were analyzed by fitted linear modeling. The use and effects on total exposure of dose reduction strategies (high pitch, adaptive statistical iterative reconstruction [ASIR], and low tube voltage) were analyzed. The overall mean dose for chest CT was 7.3 ± 5.1 mSv. The mean dose decreased by 30%, from 9.2 mSv (2007-2009) to 6.5 mSv (2010-2012) (P < .001). From 2007 to 2009, the mean dose increased by 1.2 mSv per year (P < .01). From 2010 to 2012, the mean dose decreased by 1.1 mSv per year (P < 0.01). High-pitch technique, ASIR, and low tube voltage increased significantly after dose reduction implementation. High pitch and ASIR were significantly associated with a reduced dose, whereas the effect of reduced voltage was not significant. Reductions in radiation exposure from medical imaging rely on ongoing technical developments and consistent, vigilant use of dose reduction strategies. This comprehensive dose reduction strategy significantly reduced radiation exposure from chest CT. Annual increases in radiation dose reversed after the strategy was implemented and continued to decline over the study period. Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  11. 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.

  12. Radiation dose reduction in the cardiac catheterization laboratory utilizing a novel protocol.

    PubMed

    Wassef, Anthony W A; Hiebert, Brett; Ravandi, Amir; Ducas, John; Minhas, Kunal; Vo, Minh; Kass, Malek; Parmar, Gurpreet; Hussain, Farrukh

    2014-05-01

    This study reports the results a novel radiation reduction protocol (RRP) system for coronary angiography and interventional procedures and the determinants of radiation dose. The cardiac catheterization laboratory is an important source of radiation and should be kept in good working order with dose-reduction and monitoring capabilities. All diagnostic coronary angiograms and percutaneous coronary interventions from a single catheterization laboratory were analyzed 2 months before and after RRP implementation. The primary outcome was the relative dose reduction at the interventional reference point. Separate analyses were done for conventional 15 frames/s (FPS) and at reduced 7.5 FPS post-RRP groups. A total of 605 patients underwent coronary angiography (309 before RRP and 296 after RRP), with 129 (42%) and 122 (41%) undergoing percutaneous coronary interventions before and after RRP, respectively. With RRP, a 48% dose reduction (1.07 ± 0.05 Gy vs. 0.56 ± 0.03 Gy, p < 0.0001) was obtained, 35% with 15 FPS RRP (0.70 ± 0.05 Gy, p < 0.0001) and 62% with 7.5 FPS RRP (0.41 ± 0.03 Gy, p < 0.001). Similar dose reductions for diagnostic angiograms and percutaneous coronary interventions were noted. There was no change in the number of stents placed or vessels intervened on. Increased dose was associated with male sex, radial approach, increasing body mass index, cine runs, and frame rates. Using a multivariable model, a 48% relative risk with RRP (p < 0.001), 44% with 15 FPS RRP and 68% with 7.5 FPS RRP was obtained. We demonstrate a highly significant 48.5% adjusted radiation dose reduction using a novel algorithm, which needs strong consideration among interventional cardiology practice. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  13. Effects of dose limits reduction on the Argentine nuclear power plants

    SciTech Connect

    Palacios, E.; Curti, A.; Massera, G.; Spano, F.; Boutet, L. )

    1993-11-01

    Occupational doses are evaluated in different stages of the fuel cycle and in the operation of nuclear power plants. Trends in individual dose distribution and collective doses are analyzed. The most contributive working conditions to collective dose are identified and the implications of dose limit reduction recommended by the ICRP in 1990 are assessed. It is concluded that no relevant difficulties should appear in accomplishing the new recommendations except for implementation at Atucha I, a nuclear power plant designed in the 1960s. Some options to reduce individual and collective doses in this plant are analyzed. The change of fuel channels by new ones free from cobalt is essential to get effective improvement of occupational exposures.

  14. A study on the indirect urea dosing method in the Selective Catalytic Reduction system

    NASA Astrophysics Data System (ADS)

    Brzeżański, M.; Sala, R.

    2016-09-01

    This article presents the results of studies on concept solution of dosing urea in a gas phase in a selective catalytic reduction system. The idea of the concept was to heat-up and evaporate the water urea solution before introducing it into the exhaust gas stream. The aim was to enhance the processes of urea converting into ammonia, what is the target reductant for nitrogen oxides treatment. The study was conducted on a medium-duty Euro 5 diesel engine with exhaust line consisting of DOC catalyst, DPF filter and an SCR system with a changeable setup allowing to dose the urea in liquid phase (regular solution) and to dose it in a gas phase (concept solution). The main criteria was to assess the effect of physical state of urea dosed on the NOx conversion ratio in the SCR catalyst. In order to compare both urea dosing methods a special test procedure was developed which consisted of six test steps covering a wide temperature range of exhaust gas generated at steady state engine operation condition. Tests were conducted for different urea dosing quantities defined by the a equivalence ratio. Based on the obtained results, a remarkable improvement in NOx reduction was found for gas urea application in comparison to the standard liquid urea dosing. Measured results indicate a high potential to increase an efficiency of the SCR catalyst by using a gas phase urea and provide the basis for further scientific research on this type of concept.

  15. Efficacy of high-pitch CT protocols for radiation dose reduction.

    PubMed

    Guberina, N; Lechel, U; Forsting, M; Ringelstein, A

    2016-12-01

    Various strategies have been developed to reduce radiation exposure of patients in CT examinations. The aim of this study was to evaluate the efficacy of high pitch in representative CT protocols examining lung embolism. We performed thermoluminescence measurements with an anthropomorphic phantom exposing it to CT algorithms for lung embolism in a 128-multislice, dual-source CT scanner: a standard CT protocol (sCT) and a CT protocol with a high pitch (+ F). Radiation doses for both CT algorithms were compared and the dose reduction potential of high pitch for individual organs was evaluated. As expected, the  +F mode reduced the effective dose and organ doses in the primary beam of radiation (namely, lung, bone marrow, heart, breast, skin and skeleton) compared with sCT by up to 52% for an equivalent image quality. On the contrary, for organs at the margin of the primary beam (thymus, thyroid, liver, pancreas, kidneys, colon and small intestine), the  +F mode reduced effective radiation doses by only 0-30%, compared with sCT. The dose reduction potential of the  +F mode greatly depends on the position of the organ in the scan field. While for organs in the primary beam  + F leads to a considerable dose reduction, it is less effective for tissues at the margin of the scanned area.

  16. Organ and effective dose reduction for region-of-interest (ROI) CBCT and fluoroscopy

    PubMed Central

    Xiong, Zhenyu; Vijayan, Sarath; Rudin, Stephen; Bednarek, Daniel R.

    2017-01-01

    In some medical-imaging procedures using CBCT and fluoroscopy, it may be needed to visualize only the center of the field-of-view with optimal quality. To reduce the dose to the patient as well as enable increased contrast in the region of interest (ROI) during CBCT and fluoroscopy procedures, a 0.7 mm thick Cu ROI attenuator with a circular aperture 12% of the FOV was used. The aim of this study was to quantify the dose-reduction benefit of ROI imaging during a typical CBCT and interventional fluoroscopy procedures in the head and torso. The Toshiba Infinix C-Arm System was modeled in BEAMnrc/EGSnrc with and without the ROI attenuator. Patient organ and effective doses were calculated in DOSXYZnrc/EGSnrc Monte-Carlo software for CBCT and interventional procedures. We first compared the entrance dose with and without the ROI attenuator on a 20 cm thick solid-water block. Then we simulated a CBCT scan and an interventional fluoroscopy procedure on the head and torso with and without an ROI attenuator. The results showed that the entrance-surface dose reduction in the solid water is about 85.7% outside the ROI opening and 10.5% in the ROI opening. The results showed a reduction in most organ doses of 45%–70% and in effective dose of 46%–66% compared to the dose in a CBCT scan and in an interventional procedure without the ROI attenuator. This work provides evidence of substantial reduction of organ and effective doses when using an ROI attenuator during CBCT and fluoroscopic procedures. PMID:28638169

  17. Radiation dose reduction during neurointerventional procedures by modification of default settings on biplane angiography equipment.

    PubMed

    Kahn, Elyne N; Gemmete, Joseph J; Chaudhary, Neeraj; Thompson, Byron Gregory; Chen, Kevin; Christodoulou, Emmanuel G; Pandey, Aditya S

    2016-08-01

    Neurointerventional procedures represent a significant source of ionizing radiation. We sought to assess the effect during neurointerventional procedures of varying default rates of radiation dose in fluoroscopy (F) and image acquisition (IA) modes, and frame rates during cine acquisition (CINE) on total X-ray dose, acquisition exposures, fluoroscopy time, and complications. We retrospectively reviewed procedures performed with two radiation dose and CINE settings: a factory setting dose cohort (30 patients, F 45 nGy/pulse, IA 3.6 μGy/pulse, factory CINE frame rate) and a reduced dose cohort (30 patients, F 32 nGy/pulse, IA 1.2 μGy/pulse, with a decreased CINE frame rate). Total radiation dose, dose area product, number of acquisition exposures, fluoroscopy time, and complications were compared between the groups. Means comparisons (t tests) were employed to evaluate differences in the outcome variables between the two groups. p Value <0.05 was considered significant. The reduced dose cohort had a significant reduction in mean radiation dose (factory, 3650 mGy; reduced, 1650 mGy; p=0.005) and dose area product (factory, 34 700 μGy×m(2); reduced, 15 000 μGy×m(2); p=0.02). There were no significant differences between cohorts in acquisition exposure (p=0.73), fluoroscopy time (p=0.45), or complications. Significant reductions in radiation dose delivered by neurointerventional procedures can be achieved through simple modifications of default radiation dose in F and IA and frame rate during CINE without an increase in procedural complexity (fluoroscopy time) or rate of complications. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  18. Reduction of Dose to the Contralateral Breast by Superflab Use in Radiation Therapy for Mammary Carcinomas

    PubMed

    Solanki, Akanksha; M, Athiyaman; A, Hemalatha; Kumar, H S

    2017-04-01

    Background: Radiation therapy is an integral part of multimodality treatment for locally advanced carcinoma of breast. Radiation doses to nearby critical normal structures like heart, lungs, and contralateral breast (CLB increases risk of second malignancies. In this study, we measured doses to the CLB and studied effects of a 1 cm thickness superflap. Materials and Methods: Fifty post-mastectomy carcinoma breast patients were included in the study.Radiation therapy of 50 Gy was planned in 25 fractions, 5 days a week, using the Eclipse Treatment Planning System version 8.9.15, with a pencil beam convolution algorithm and 6 MV photon beam. Plans were transferred to a linear accelerator (Varian 2300 CD) for execution of treatment. Twenty-four CaSO4 thermoluminescent dosimeter discs (TLDs) were used for dose measurement over the CLB. The dose was measured for each patient without a superflab for ten fractions and with for another ten fractions for subsequent comparison. Results: Mean doses/fractions received by the CLB with and without a superflab? were 3.78 ± 1.29 cGy and 7.82 ± 2.62 cGy, respectively, with total dosees of 94.69 ± 32.43 cGy (1.89% of prescribed dose) and 191.14 ± 65.62 cGy (3.82% of prescribed dose). The average reduction in mean dose with a 1 cm thick superflab was 46.57 ± 17.18%, in the range of 20 to 80% and statistically significant (p < 0.001). Conclusion: Superflab? is an effective method for dose reduction to CLB. It is an easy, convenient and low time consuming method. Elucidation of any role in reduction of 2nd malignancies in CLB now needs large studies with long follow-up. Creative Commons Attribution License

  19. Reduction of Dose to the Contralateral Breast by Superflab Use in Radiation Therapy for Mammary Carcinomas

    PubMed Central

    Solanki, Akanksha; M, Athiyaman; A, Hemalatha; Kumar, H S

    2017-01-01

    Background: Radiation therapy is an integral part of multimodality treatment for locally advanced carcinoma of breast. Radiation doses to nearby critical normal structures like heart, lungs, and contralateral breast (CLB increases risk of second malignancies. In this study, we measured doses to the CLB and studied effects of a 1 cm thickness superflap. Materials and Methods: Fifty post-mastectomy carcinoma breast patients were included in the study. Radiation therapy of 50 Gy was planned in 25 fractions, 5 days a week, using the Eclipse Treatment Planning System version 8.9.15, with a pencil beam convolution algorithm and 6 MV photon beam. Plans were transferred to a linear accelerator (Varian 2300 CD) for execution of treatment. Twenty-four CaSO4 thermoluminescent dosimeter discs (TLDs) were used for dose measurement over the CLB. The dose was measured for each patient without a superflab for ten fractions and with for another ten fractions for subsequent comparison. Results: Mean doses/fractions received by the CLB with and without a superflab? were 3.78 ± 1.29 cGy and 7.82 ± 2.62 cGy, respectively, with total dosees of 94.69 ± 32.43 cGy (1.89% of prescribed dose) and 191.14 ± 65.62 cGy (3.82% of prescribed dose). The average reduction in mean dose with a 1 cm thick superflab was 46.57 ± 17.18%, in the range of 20 to 80% and statistically significant (p < 0.001). Conclusion: Superflab? is an effective method for dose reduction to CLB. It is an easy, convenient and low time consuming method. Elucidation of any role in reduction of 2nd malignancies in CLB now needs large studies with long follow-up. PMID:28545264

  20. Radiation dose reduction in time-resolved CT angiography using highly constrained back projection reconstruction

    PubMed Central

    Supanich, Mark; Tao, Yinghua; Nett, Brian; Pulfer, Kari; Hsieh, Jiang; Turski, Patrick; Mistretta, Charles; Rowley, Howard; Chen, Guang-Hong

    2010-01-01

    Recently dynamic, time-resolved three-dimensional computed tomography angiography (CTA) has been introduced to the neurological imaging community. However, the radiation dose delivered to patients in time-resolved CTA protocol is a high and potential risk associated with the ionizing radiation dose. Thus, minimizing the radiation dose is highly desirable for time-resolved CTA. In order to reduce the radiation dose delivered during dynamic, contrast-enhanced CT applications, we introduce here the CT formulation of HighlY constrained back PRojection (HYPR) imaging. We explore the radiation dose reduction approaches of both acquiring a reduced number of projections for each image and lowering the tube current used during acquisition. We then apply HYPR image reconstruction to produce image sets at a reduced patient dose and with low image noise. Numerical phantom experiments and retrospective analysis of in vivo canine studies are used to assess the accuracy and quality of HYPR reduced dose image sets and validate our approach. Experimental results demonstrated that a factor of 6–8 times radiation dose reduction is possible when the HYPR algorithm is applied to time-resolved CTA exams. PMID:19567941

  1. 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

  2. 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%.

  3. 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

  4. Working Face-to-Face for Pediatric CT Dose Reduction: A Community Toolkit

    PubMed Central

    Armao, Diane; Hartman, Terry; Shea, Christopher M.; Sams, Cassandra; Fordham, Lynn Ansley; Smith, J. Keith

    2016-01-01

    Although children are especially vulnerable to the health risks of ionizing radiation, approximately 8 million CTs are performed on children in the USA. Widespread dose variation is common, particularly in non-pediatric focused facilities. In this article we present our rationale and hands-on approach in developing and refining a toolkit aimed at helping a community hospital with pediatric CT dose reduction. PMID:27942250

  5. [Budget impact analysis of efavirenz daily dose reduction at the Verona University Hospital].

    PubMed

    Costa, Enrico; Biasi, Valeria; Concia, Ercole; Jommi, Claudio; Lattuada, Emanuela; Manfre, Silvia; Venturini, Francesca; Lanzafame, Massimiliano

    2014-06-01

    Efavirenz is a non-nucleoside-reverse-transcriptase-inhibitor used as part of highly-active-antiretroviral-therapy for the treatment of the human immunodeficiency virus (HIV) type 1 infection. The present paper aims to describing the impact of efavirenz dose reduction on the pharmaceutical budget at the Verona University Hospital. A budget impact analysis comparing two prescribing scenarios was conducted: all patients treated with the efavirenz full dose (600 mg per day) vs. a proportion of patients treated with a reduced dose (200-400 mg per day). All outpatients referring to the Infectious Disease Clinic in the period November 2009-October 2011 were selected. Out of 132 patients treated with efavirenz, 25 were not considered, mainly due to a too short treatment period. Of the remaining 107 patients, 68 received the full dose, while 39 received a reduced dosage. The analysis included the cost of the drug and of diagnostic tests, from the National Health Service perspective. The daily dose reduction of efavirenz saved 54,664 euros (a 30% expenditure reduction). In sum, new strategies for pharmaceutical system sustainability are necessary; despite forthcoming expiring patents of several drugs, spending on antiretroviral drugs is expected to rise. This paper suggests a way of linking clinical benefits and cost reduction.

  6. X-ray dose reduction by adaptive source equalization and electronic region-of-interest control

    NASA Astrophysics Data System (ADS)

    Burion, Steve; Sandman, Anne; Bechtel, Kate; Solomon, Edward; Funk, Tobias

    2011-03-01

    Radiation dose is particularly a concern in pediatric cardiac fluoroscopy procedures, which account for 7% of all cardiac procedures performed. The Scanning-Beam Digital X-ray (SBDX) fluoroscopy system has already demonstrated reduced dose in adult patients owing to its high-DQE photon-counting detector, reduced detected scatter, and the elimination of the anti-scatter grid. Here we show that the unique flexible illumination platform of the SBDX system will enable further dose area product reduction, which we are currently developing for pediatric patients, but which will ultimately benefit all patients. The SBDX system has a small-area detector array and a large-area X-ray source with up to 9,000 individually-controlled X-ray focal spots. Each focal spot illuminates a small fraction of the full field of view. To acquire a frame, each focal spot is activated for a fixed number of 1-microsecond periods. Dose reduction is made possible by reducing the number of activations of some of the X-ray focal spots during each frame time. This can be done dynamically to reduce the exposure in areas of low patient attenuation, such as the lung field. This spatially-adaptive illumination also reduces the dynamic range in the full image, which is visually pleasing. Dose can also be reduced by the user selecting a region of interest (ROI) where full image quality is to be maintained. Outside the ROI, the number of activations of each X-ray focal spot is reduced and the image gain is correspondingly increased to maintain consistent image brightness. Dose reduction is dependent on the size of the ROI and the desired image quality outside the ROI. We have developed simulation software that is based on real data and can simulate the performance of the equalization and ROI filtration. This software represents a first step toward real-time implementation of these dose-reduction methods. Our simulations have shown that dose area product reductions of 40% are possible using equalization

  7. Dose reduction with iterative reconstruction for coronary CT angiography: a systematic review and meta-analysis

    PubMed Central

    Willemink, Martin J; De Ruiter, Quirina M B; De Jong, Pim A; Schilham, Arnold M R; Krestin, Gabriel P; Leiner, Tim; Budde, Ricardo P J

    2016-01-01

    Objective: To investigate the achievable radiation dose reduction for coronary CT angiography (CCTA) with iterative reconstruction (IR) in adults and the effects on image quality. Methods: PubMed and EMBASE were searched, and original articles concerning IR for CCTA in adults using prospective electrocardiogram triggering were included. Primary outcome was the effective dose using filtered back projection (FBP) and IR. Secondary outcome was the effect of IR on objective and subjective image quality. Results: The search yielded 1616 unique articles, of which 10 studies (1042 patients) were included. The pooled routine effective dose with FBP was 4.2 mSv [95% confidence interval (CI) 3.5–5.0]. A dose reduction of 48% to a pooled effective dose of 2.2 mSv (95% CI 1.3–3.1) using IR was reported. Noise, contrast-to-noise ratio and subjective image quality were equal or improved in all but one study, whereas signal-to-noise ratio was decreased in two studies with IR at reduced dose. Conclusion: IR allows for CCTA acquisition with an effective dose of 2.2 mSv with preserved objective and subjective image quality. PMID:26562096

  8. Marked reduction of effective radiation dose in patients undergoing CT coronary angiography using prospective ECG gating.

    PubMed

    Freeman, Anthony; Learner, Ruth; Eggleton, Simon; Lambros, John; Friedman, Daniel

    2011-08-01

    Coronary CT angiography (CCTA) is a rapidly evolving technology which can characterise and image sub clinical atherosclerotic plaque and visualise anatomy and quantitate stenosis. Concern about radiation exposure has limited the uptake of this technology. The aim of this study was to review the radiation dose data in 2298 consecutive patients referred to a single centre in an Australian outpatient setting over 27 months using all available radiation dose reduction strategies. Prospective ECG gating ("step and shoot") was used preferentially in 2025 patients with a mean effective dose of 3.39 ± 1.84 mSv (range 0.86-12.6 mSv). For clinical reasons only 273 patients required retrospective ECG gating, mean dose 19.21 ± 5.58 mSv (range 2.4-34.9 mSv) resulting in an 85.7% reduction in dose for the majority of patients with the low dose technique. In conclusion, most patients referred for routine CCTA can be studied with a radiation dose comparable to invasive X-ray angiography and less than radionuclide myocardial perfusion imaging. Copyright © 2011 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of Australia and New Zealand. Published by Elsevier B.V. All rights reserved.

  9. New image-processing and noise-reduction software reduces radiation dose during complex endovascular procedures.

    PubMed

    Kirkwood, Melissa L; Guild, Jeffrey B; Arbique, Gary M; Tsai, Shirling; Modrall, J Gregory; Anderson, Jon A; Rectenwald, John; Timaran, Carlos

    2016-11-01

    A new proprietary image-processing system known as AlluraClarity, developed by Philips Healthcare (Best, The Netherlands) for radiation-based interventional procedures, claims to lower radiation dose while preserving image quality using noise-reduction algorithms. This study determined whether the surgeon and patient radiation dose during complex endovascular procedures (CEPs) is decreased after the implementation of this new operating system. Radiation dose to operators, procedure type, reference air kerma, kerma area product, and patient body mass index were recorded during CEPs on two Philips Allura FD 20 fluoroscopy systems with and without Clarity. Operator dose during CEPs was measured using optically stimulable, luminescent nanoDot (Landauer Inc, Glenwood, Ill) detectors placed outside the lead apron at the left upper chest position. nanoDots were read using a microStar ii (Landauer Inc) medical dosimetry system. For the CEPs in the Clarity group, the radiation dose to surgeons was also measured by the DoseAware (Philips Healthcare) personal dosimetry system. Side-by-side measurements of DoseAware and nanoDots allowed for cross-calibration between systems. Operator effective dose was determined using a modified Niklason algorithm. To control for patient size and case complexity, the average fluoroscopy dose rate and the dose per radiographic frame were adjusted for body mass index differences and then compared between the groups with and without Clarity by procedure. Additional factors, for example, physician practice patterns, that may have affected operator dose were inferred by comparing the ratio of the operator dose to procedural kerma area product with and without Clarity. A one-sided Wilcoxon rank sum test was used to compare groups for radiation doses, reference air kermas, and operating practices for each procedure type. The analysis included 234 CEPs; 95 performed without Clarity and 139 with Clarity. Practice patterns of operators during

  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. SparseCT: interrupted-beam acquisition and sparse reconstruction for radiation dose reduction

    NASA Astrophysics Data System (ADS)

    Koesters, Thomas; Knoll, Florian; Sodickson, Aaron; Sodickson, Daniel K.; Otazo, Ricardo

    2017-03-01

    State-of-the-art low-dose CT methods reduce the x-ray tube current and use iterative reconstruction methods to denoise the resulting images. However, due to compromises between denoising and image quality, only moderate dose reductions up to 30-40% are accepted in clinical practice. An alternative approach is to reduce the number of x-ray projections and use compressed sensing to reconstruct the full-tube-current undersampled data. This idea was recognized in the early days of compressed sensing and proposals for CT dose reduction appeared soon afterwards. However, no practical means of undersampling has yet been demonstrated in the challenging environment of a rapidly rotating CT gantry. In this work, we propose a moving multislit collimator as a practical incoherent undersampling scheme for compressed sensing CT and evaluate its application for radiation dose reduction. The proposed collimator is composed of narrow slits and moves linearly along the slice dimension (z), to interrupt the incident beam in different slices for each x-ray tube angle (θ). The reduced projection dataset is then reconstructed using a sparse approach, where 3D image gradients are employed to enforce sparsity. The effects of the collimator slits on the beam profile were measured and represented as a continuous slice profile. SparseCT was tested using retrospective undersampling and compared against commercial current-reduction techniques on phantoms and in vivo studies. Initial results suggest that SparseCT may enable higher performance than current-reduction, particularly for high dose reduction factors.

  12. [Application of adaptive iterative dose reduction technique in CT enterography in diagnosing Crohn disease].

    PubMed

    Lian, Yanbang; Cao, Wuteng; Zhu, Shanshan; Lin, Yanghao; Liu, Dechao; Wang, Xinhua; Qiu, Jianping; Zhou, Zhiyang

    2014-07-01

    To evaluate the application of low-dose CT enterography with adaptive iterative dose reduction(AIDR) technique in diagnosing Crohn's disease. Retrospective analysis was performed on 26 patients diagnosed as Crohn's disease by the multidisciplinary team in our hospital. Low-dose CT enterography with 640-slice MDCT was performed on these 26 patients using adaptive iterative dose reduction(AIDR) technique. Characteristics of Crohn's disease in CT enterography images were independently analyzed by two radiologists who were experienced in Crohn's disease with calculating the total radiation dosage. The radiation dosage of 26 patients ranged from 5.58 to 12.90 [mean (9.00±2.00)] mSv, which was lower than conventional scan (around 15 mSv) known from the literatures. According to the images of CT enterography of 26 cases, bowel wall thickening with abnormal enhancement and lymphadenectasis were found in 25 cases with total 109 segmental bowel wall thickening. Among 25 thickening cases, enterostenosis was found in 16 cases, stratification enhancement in 12 cases and comb sign in 14 cases. Besides, it was found that 8 cases with hyperdense fat on the mesenteric side, 7 cases with intestinal fistula, 6 cases with abdominal cavity abscess, and 3 cases with anal fistula. CT enterography of Crohn's disease with adaptive iterative dose reduction technique is an effective method to evaluate Crohn's disease without compromising image quality with reduced radiation dosage.

  13. 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…

  14. 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…

  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. Role of TRPV1 in nociception and edema induced by monosodium urate crystals in rats.

    PubMed

    Hoffmeister, Carin; Trevisan, Gabriela; Rossato, Mateus Fortes; de Oliveira, Sara Marchesan; Gomez, Marcus Vinícius; Ferreira, Juliano

    2011-08-01

    Gout is characterized by the deposition of monosodium urate (MSU) crystals. Despite being one of the most painful forms of arthritis, gout and the mechanisms responsible for its acute attacks are poorly understood. In the present study, we found that MSU caused dose-related nociception (ED(50) [ie, the necessary dose of MSU to elicit 50% of the response relative to the control value]=0.04 [95% confidence interval 0.01-0.11]mg/paw) and edema (ED(50)=0.08 [95% confidence interval 0.04-0.16]mg/paw) when injected into the hind paw of rats. Treatment with the selective TRPV1 receptor (also known as capsaicin receptor and vanilloid receptor-1) antagonists SB366791 or AMG9810 largely prevented nociceptive and edematogenic responses to MSU. Moreover, the desensitization of capsaicin-sensitive afferent fibers as well as pretreatment with the tachykinin NK(1) receptor antagonist RP 67580 also significantly prevented MSU-induced nociception and edema. Once MSU was found to induce mast cell stimulation, we investigated the participation of these cells on MSU effects. Prior degranulation of mast cells by repeated treatment with the compound 48/80 decreased MSU-induced nociception and edema or histamine and serotonin levels in the injected tissue. Moreover, pretreatment with the mast cell membrane stabilizer cromolyn effectively prevented nociceptive and edematogenic responses to MSU. MSU induced a release of histamine, serotonin, and tryptase in the injected tissue, confirming mast cell degranulation. Furthermore, the antagonism of histaminergic H1 and serotoninergic receptors decreased the edema, but not the nociception of MSU. Finally, the prevention of the tryptase activity was capable of largely reducing both MSU-induced nociception and edema. Collectively, the present findings demonstrate that MSU produces nociceptive and edematogenic responses mediated by TRPV1 receptor activation and mast cell degranulation. Copyright © 2011 International Association for the Study of

  17. Radiation dose reduction to the male gonads during MDCT: the effectiveness of a lead shield.

    PubMed

    Hohl, Christian; Mahnken, Andreas H; Klotz, Ernst; Das, Marco; Stargardt, Achim; Mühlenbruch, Georg; Schmidt, Thorsten; Günther, Rolf W; Wildberger, Joachim E

    2005-01-01

    Our study was designed to quantify the effect of a standard gonad shield on the testicular radiation exposure due to scatter during routine abdominopelvic MDCT. Routine abdominopelvic MDCT was performed in 34 patients with gonadal lead shielding and 32 patients without this shielding; the testes were not exposed to the direct beam during the examination. We estimated the testicular dose administered with thermoluminescent dosimetry, taking into account each patient's body weight and body mass index (BMI). With a 1-mm lead shield, the mean testicular dose was reduced from 2.40 to 0.32 mSv, a reduction of 87%. The difference was found to be statistically significant (p < 0.0001). No correlation between testicular dose and body weight or BMI was found. Shielding the male gonads reduces the testicular radiation dose during abdominopelvic MDCT significantly and can be recommended for routine use.

  18. Radiation dose reduction in CT myocardial perfusion imaging using SMART-RECON.

    PubMed

    Li, Yinsheng; Speidel, Michael A; Francois, Christopher J; Chen, Guang-Hong

    2017-08-30

    In this work, a newly developed statistical model based image reconstruction (referred to as Simultaneous Multiple Artifacts Reduction in Tomographic RECONstruction (SMARTRECON) [1]) is applied to low dose computer tomography (CT) myocardial perfusion imaging (CT-MPI). This method uses the nuclear norm of the spatial-temporal image matrix of the CTMPI images as a regularizer, rather than a conventional spatial regularizer that incorporates image smoothness, edge preservation, or spatial sparsity into the reconstruction. In addition to providing the needed noise reduction for low-dose CT-MPI, SMART-RECON provides images with spatial resolution and noise power spectrum (NPS) properties which are independent of contrast and dose level. Both numerical simulations and in vivo animal studies were performed to validate the proposed method. In these studies, it was found that: (1) Quantitative accuracy of perfusion maps in CT-MPI was well maintained for radiation dose level as low as 10 mAs per image frame, compared with the reference standard of 200 mAs for conventional filtered backprojection (FBP); (2) Flow-occluded myocardium in the porcine heart was well delineated by SMART-RECON at 10 mAs per frame when compared with MBIR using spatial total variation (TV) as the regularizer (referred to as TV-SIR) or Spatial-Temporal TV (ST-TV-SIR); The CT-MPI results were confirmed with PET imaging; (3) Image sharpness in SMARTRECON images was nearly independent of image contrast level and radiation dose level, in stark contrast to TV-SIR and STTV- SIR which displayed a strong dependence on both image contrast and radiation dose level; (4) The structure of the dosenormalized NPS for the SMART-RECON method did not depend on dose, while the TV-SIR and ST-TV-SIR NPS structure was dose-dependent.

  19. 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

  20. 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.

  1. Paediatric x-ray radiation dose reduction and image quality analysis.

    PubMed

    Martin, L; Ruddlesden, R; Makepeace, C; Robinson, L; Mistry, T; Starritt, H

    2013-09-01

    Collaboration of multiple staff groups has resulted in significant reduction in the risk of radiation-induced cancer from radiographic x-ray exposure during childhood. In this study at an acute NHS hospital trust, a preliminary audit identified initial exposure factors. These were compared with European and UK guidance, leading to the introduction of new factors that were in compliance with European guidance on x-ray tube potentials. Image quality was assessed using standard anatomical criteria scoring, and visual grading characteristics analysis assessed the impact on image quality of changes in exposure factors. This analysis determined the acceptability of gradual radiation dose reduction below the European and UK guidance levels. Chest and pelvis exposures were optimised, achieving dose reduction for each age group, with 7%-55% decrease in critical organ dose. Clinicians confirmed diagnostic image quality throughout the iterative process. Analysis of images acquired with preliminary and final exposure factors indicated an average visual grading analysis result of 0.5, demonstrating equivalent image quality. The optimisation process and final radiation doses are reported for Carestream computed radiography to aid other hospitals in minimising radiation risks to children.

  2. Preemptive warfarin dose reduction after initiation of sulfamethoxazole-trimethoprim or metronidazole.

    PubMed

    Powers, Anna; Loesch, Erin B; Weiland, Anthony; Fioravanti, Nicole; Lucius, David

    2017-07-01

    To evaluate the utility of a preemptive warfarin dose reduction at the time of initiation of either sulfamethoxazole-trimethoprim or metronidazole, a retrospective chart review of patients who received an outpatient prescription for warfarin and either sulfamethoxazole-trimethoprim and/or metronidazole from July 1, 2011 to July 1, 2015 was conducted. Clinical outcomes compared Veterans who had a warfarin dose reduction and those who did not within 120 h (5 days) of antibiotic initiation. The primary outcome compared the pre-and post-antibiotic International Normalized Ratio (INR) of patients in the intervention group (warfarin dose reduction) with those in the control group (no intervention). Secondary outcomes assessed incidence of thromboembolic and major bleeding events within 30 days of antibiotic completion. Fifty patients were assessed. Forty-nine patients had at least one follow-up appointment; 126 follow-up visits were evaluated. There was a statistically significant difference for the change in therapeutic INR at the first follow-up appointment (p = 0.029) for those patients in the control group. On average, the patients in the intervention group required fewer follow-up visits (p = 0.019). There were no statistically significant differences for the overall rate of therapeutic INR values between groups, as well as no instances of a thromboembolic or major bleeding events during the follow-up period. Clinically significant differences were observed for patients who received a preemptive warfarin dose reduction upon initiation of sulfamethoxazole-trimethoprim or metronidazole. Patients in the intervention group required fewer follow-up appointments and were more likely maintain a therapeutic INR within the 30 days following the antibiotic course. Results of this study will be presented the at Pharmacy and Therapeutics committee in an effort to seek approval for policy development to initiate a local preemptive warfarin dose adjustment as a standard

  3. Effects of dose reduction on bone strength prediction using finite element analysis

    NASA Astrophysics Data System (ADS)

    Anitha, D.; Subburaj, Karupppasamy; Mei, Kai; Kopp, Felix K.; Foehr, Peter; Noel, Peter B.; Kirschke, Jan S.; Baum, Thomas

    2016-12-01

    This study aimed to evaluate the effect of dose reduction, by means of tube exposure reduction, on bone strength prediction from finite-element (FE) analysis. Fresh thoracic mid-vertebrae specimens (n = 11) were imaged, using multi-detector computed tomography (MDCT), at different intensities of X-ray tube exposures (80, 150, 220 and 500 mAs). Bone mineral density (BMD) was estimated from the mid-slice of each specimen from MDCT images. Differences in image quality and geometry of each specimen were measured. FE analysis was performed on all specimens to predict fracture load. Paired t-tests were used to compare the results obtained, using the highest CT dose (500 mAs) as reference. Dose reduction had no significant impact on FE-predicted fracture loads, with significant correlations obtained with reference to 500 mAs, for 80 mAs (R2  = 0.997, p < 0.001), 150 mAs (R2 = 0.998, p < 0.001) and 220 mAs (R2 = 0.987, p < 0.001). There were no significant differences in volume quantification between the different doses examined. CT imaging radiation dose could be reduced substantially to 64% with no impact on strength estimates obtained from FE analysis. Reduced CT dose will enable early diagnosis and advanced monitoring of osteoporosis and associated fracture risk.

  4. Effects of dose reduction on bone strength prediction using finite element analysis

    PubMed Central

    Anitha, D.; Subburaj, Karupppasamy; Mei, Kai; Kopp, Felix K.; Foehr, Peter; Noel, Peter B.; Kirschke, Jan S.; Baum, Thomas

    2016-01-01

    This study aimed to evaluate the effect of dose reduction, by means of tube exposure reduction, on bone strength prediction from finite-element (FE) analysis. Fresh thoracic mid-vertebrae specimens (n = 11) were imaged, using multi-detector computed tomography (MDCT), at different intensities of X-ray tube exposures (80, 150, 220 and 500 mAs). Bone mineral density (BMD) was estimated from the mid-slice of each specimen from MDCT images. Differences in image quality and geometry of each specimen were measured. FE analysis was performed on all specimens to predict fracture load. Paired t-tests were used to compare the results obtained, using the highest CT dose (500 mAs) as reference. Dose reduction had no significant impact on FE-predicted fracture loads, with significant correlations obtained with reference to 500 mAs, for 80 mAs (R2  = 0.997, p < 0.001), 150 mAs (R2 = 0.998, p < 0.001) and 220 mAs (R2 = 0.987, p < 0.001). There were no significant differences in volume quantification between the different doses examined. CT imaging radiation dose could be reduced substantially to 64% with no impact on strength estimates obtained from FE analysis. Reduced CT dose will enable early diagnosis and advanced monitoring of osteoporosis and associated fracture risk. PMID:27934902

  5. Characterization and quantification of cerebral edema induced by synchrotron x-ray microbeam radiation therapy

    NASA Astrophysics Data System (ADS)

    Serduc, Raphaël; van de Looij, Yohan; Francony, Gilles; Verdonck, Olivier; van der Sanden, Boudewijn; Laissue, Jean; Farion, Régine; Bräuer-Krisch, Elke; Siegbahn, Erik Albert; Bravin, Alberto; Prezado, Yolanda; Segebarth, Christoph; Rémy, Chantal; Lahrech, Hana

    2008-03-01

    Cerebral edema is one of the main acute complications arising after irradiation of brain tumors. Microbeam radiation therapy (MRT), an innovative experimental radiotherapy technique using spatially fractionated synchrotron x-rays, has been shown to spare radiosensitive tissues such as mammal brains. The aim of this study was to determine if cerebral edema occurs after MRT using diffusion-weighted MRI and microgravimetry. Prone Swiss nude mice's heads were positioned horizontally in the synchrotron x-ray beam and the upper part of the left hemisphere was irradiated in the antero-posterior direction by an array of 18 planar microbeams (25 mm wide, on-center spacing 211 mm, height 4 mm, entrance dose 312 Gy or 1000 Gy). An apparent diffusion coefficient (ADC) was measured at 7 T 1, 7, 14, 21 and 28 days after irradiation. Eventually, the cerebral water content (CWC) was determined by microgravimetry. The ADC and CWC in the irradiated (312 Gy or 1000 Gy) and in the contralateral non-irradiated hemispheres were not significantly different at all measurement times, with two exceptions: (1) a 9% ADC decrease (p < 0.05) was observed in the irradiated cortex 1 day after exposure to 312 Gy, (2) a 0.7% increase (p < 0.05) in the CWC was measured in the irradiated hemispheres 1 day after exposure to 1000 Gy. The results demonstrate the presence of a minor and transient cellular edema (ADC decrease) at 1 day after a 312 Gy exposure, without a significant CWC increase. One day after a 1000 Gy exposure, the CWC increased, while the ADC remained unchanged and may reflect the simultaneous presence of cellular and vasogenic edema. Both types of edema disappear within a week after microbeam exposure which may confirm the normal tissue sparing effect of MRT. For more information on this article, see medicalphysicsweb.org

  6. Implementing smart infusion pumps with dose-error reduction software: real-world experiences.

    PubMed

    Heron, Claire

    2017-04-27

    Intravenous (IV) drug administration, especially with 'smart pumps', is complex and susceptible to errors. Although errors can occur at any stage of the IV medication process, most errors occur during reconstitution and administration. Dose-error reduction software (DERS) loaded on to infusion pumps incorporates a drug library with predefined upper and lower drug dose limits and infusion rates, which can reduce IV infusion errors. Although this is an important advance for patient safety at the point of care, uptake is still relatively low. This article discuses the challenges and benefits of implementing DERS in clinical practice as experienced by three UK trusts.

  7. Thyroid shields versus z-axis automatic tube current modulation for dose reduction at neck CT.

    PubMed

    Leswick, David A; Hunt, Megan M; Webster, Steven T; Fladeland, Derek A

    2008-11-01

    To assess the effectiveness of in-plane bismuth thyroid shields and a z-axis automatic tube current modulation (ATCM) technique with respect to dose reduction and image noise in the thyroid and other regional tissues during neck computed tomography (CT). Because this was a phantom study, neither institutional review board approval nor HIPAA compliance was required. A female phantom, thyroid shields, and an eight-section CT scanner were used. Radiation dose was measured by using thermoluminescent dosimetry (TLD) chips placed in the phantom's thyroid, cervical bone marrow, and soft tissues. Scans were performed by using fixed tube current and a z-axis ATCM technique with and without shields. Image noise was quantified as the standard deviation of the attenuation value (in Hounsfield units) on CT images. Thyroid dose was 76.9 mGy with an unshielded fixed tube current technique. Use of shields and ATCM reduced this dose to 44.7 mGy (42% reduction, P < .001) and 17.0 mGy (78% reduction, P < .001), respectively. The combination of shields and ATCM further reduced this dose to between 11.9 and 12.9 mGy (83%-85% reduction, P < .001), depending on the shield's presence in the scout scan. ATCM resulted in minimized tube current throughout the neck, which reduced dose-length product across the entire scan volume by 60% (926 vs 368 mGy . cm). Thyroid bed noise was lowest (3.9 HU) during the fixed tube current technique without shields, with noise slightly higher (6.9 HU) with the unshielded ATCM technique (P < .001). Thyroid image noise was markedly higher when using shields (P < .001), with noise measuring between 74 and 113 HU for fixed tube current and ATCM scans. z-Axis ATCM is more effective than shields at reducing thyroid radiation dose during neck CT. Shields combined with ATCM slightly further reduces dose; however, this is associated with higher image noise. (c) RSNA, 2008.

  8. Effects of radiation dose reduction in Volume Perfusion CT imaging of acute ischemic stroke.

    PubMed

    Othman, Ahmed E; Brockmann, Carolin; Yang, Zepa; Kim, Changwon; Afat, Saif; Pjontek, Rastislav; Nikobashman, Omid; Brockmann, Marc A; Kim, Jong Hyo; Wiesmann, Martin

    2015-12-01

    To examine the influence of radiation dose reduction on image quality and sensitivity of Volume Perfusion CT (VPCT) maps regarding the detection of ischemic brain lesions. VPCT data of 20 patients with suspected ischemic stroke acquired at 80 kV and 180 mAs were included. Using realistic reduced-dose simulation, low-dose VPCT datasets with 144 mAs, 108 mAs, 72 mAs and 36 mAs (80 %, 60 %, 40 % and 20 % of the original levels) were generated, resulting in a total of 100 datasets. Perfusion maps were created and signal-to-noise-ratio (SNR) measurements were performed. Qualitative analyses were conducted by two blinded readers, who also assessed the presence/absence of ischemic lesions and scored CBV and CBF maps using a modified ASPECTS-score. SNR of all low-dose datasets were significantly lower than those of the original datasets (p < .05). All datasets down to 72 mAs (40 %) yielded sufficient image quality and high sensitivity with excellent inter-observer-agreements, whereas 36 mAs datasets (20 %) yielded poor image quality in 15 % of the cases with lower sensitivity and inter-observer-agreements. Low-dose VPCT using decreased tube currents down to 72 mAs (40 % of original radiation dose) produces sufficient perfusion maps for the detection of ischemic brain lesions. • Perfusion CT is highly accurate for the detection of ischemic brain lesions • Perfusion CT results in high radiation exposure, therefore low-dose protocols are required • Reduction of tube current down to 72 mAs produces sufficient perfusion maps.

  9. 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

  10. Radiation dose reduction in the invasive cardiovascular laboratory: implementing a culture and philosophy of radiation safety.

    PubMed

    Fetterly, Kenneth A; Mathew, Verghese; Lennon, Ryan; Bell, Malcolm R; Holmes, David R; Rihal, Charanjit S

    2012-08-01

    This paper investigates the effects of sustained practice and x-ray system technical changes on the radiation dose administered to adult patients during invasive cardiovascular procedures. It is desirable to reduce radiation dose associated with medical imaging to minimize the risk of adverse radiation effects to both patients and staff. Several clinical practice and technical changes to elevate radiation awareness and reduce patient radiation dose were implemented under the guidance of a cardiovascular invasive labs radiation safety committee. Practice changes included: intraprocedure radiation dose announcements; reporting of procedures for which the air-kerma exceeded 6,000 mGy, including procedure air-kerma in the clinical report; and establishing compulsory radiation safety training for fellows. Technical changes included establishing standard x-ray imaging protocols, increased use of x-ray beam spectral filters, reducing the detector target dose for fluoroscopy and acquisition imaging, and reducing the fluoroscopy frame rate to 7.5 s(-1). Patient- and procedure-specific cumulative skin dose was calculated from air-kerma values and evaluated retrospectively over a period of 3 years. Data were categorized to include all procedures, percutaneous coronary interventions, coronary angiography, noncardiac vascular angiography and interventions, and interventions to treat structural heart disease. Statistical analysis was based on a comparison of the cumulative skin dose for procedures performed during the first and last quarters of the 3-year study period. A total of 18,115 procedures were performed by 27 staff cardiologists and 65 fellows-in-training. Considering all procedures, the mean cumulative skin dose decreased from 969 to 568 mGy (40% reduction) over 3 years. This work demonstrates that a philosophy of radiation safety, implemented through a collection of sustained practice and x-ray system changes, can result in a significant decrease in the radiation dose

  11. “Rapid administration technique of ketamine for pediatric forearm fracture reduction- a dose finding study”

    PubMed Central

    Chinta, Sri S; Schrock, Charles R; McAllister, John D; Jaffe, David M; Liu, Jingxia; Kennedy, Robert M

    2014-01-01

    Study Objective To estimate the minimum dose and total sedation time of rapidly infused ketamine that achieves 3-5 minutes of effective sedation in children undergoing forearm fracture reduction in the emergency department. Methods We used the Up-Down method to estimate the median dose of intravenous ketamine infused over ≤ 5 sec that provided effective sedation in 50% (ED50) and 95% (ED95) of healthy children aged 2-5, 6-11 or 12-17 years undergoing forearm fracture reduction. Most were pretreated with opioids. Three investigators blinded to ketamine dose independently graded sedation effectiveness by viewing a video recording of the first 5 minutes of sedation. Recovery was assessed by Modified Aldrete score. Results We enrolled 20 children in each age group. The estimated ED50 was 0.7, 0.5 and 0.6 mg/kg and the estimated ED95 was 0.7, 0.7 and 0.8 mg/kg for the 2-5, 6-11 and 12-17 years age groups, respectively. For the 2-5 years age group, an empirically derived ED95 was 0.8 mg/kg. All who received the empirically derived ED95 in the 2-5 years group or the estimated ED95 in the 6-11 and 12-17 years group had effective sedation. The median total sedation time for the three age groups respectively, was 25, 22.5 and 25 minutes if one dose of ketamine was administered and 35, 25 and 45 minutes if additional doses were administered. No participant experienced serious adverse events. Conclusions We estimated ED50 and ED95 for rapidly infused ketamine for three age groups undergoing fracture reduction. Total sedation time was shorter than most previous studies. PMID:25595951

  12. Optimal treatment scheduling of ionizing radiation and sunitinib improves the antitumor activity and allows dose reduction

    PubMed Central

    Kleibeuker, Esther A; ten Hooven, Matthijs A; Castricum, Kitty C; Honeywell, Richard; Griffioen, Arjan W; Verheul, Henk M; Slotman, Ben J; Thijssen, Victor L

    2015-01-01

    The combination of radiotherapy with sunitinib is clinically hampered by rare but severe side effects and varying results with respect to clinical benefit. We studied different scheduling regimes and dose reduction in sunitinib and radiotherapy in preclinical tumor models to improve potential outcome of this combination treatment strategy. The chicken chorioallantoic membrane (CAM) was used as an angiogenesis in vivo model and as a xenograft model with human tumor cells (HT29 colorectal adenocarcinoma, OE19 esophageal adenocarcinoma). Treatment consisted of ionizing radiation (IR) and sunitinib as single therapy or in combination, using different dose-scheduling regimes. Sunitinib potentiated the inhibitory effect of IR (4 Gy) on angiogenesis. In addition, IR (4 Gy) and sunitinib (4 days of 32.5 mg/kg per day) inhibited tumor growth. Ionizing radiation induced tumor cell apoptosis and reduced proliferation, whereas sunitinib decreased tumor angiogenesis and reduced tumor cell proliferation. When IR was applied before sunitinib, this almost completely inhibited tumor growth, whereas concurrent IR was less effective and IR after sunitinib had no additional effect on tumor growth. Moreover, optimal scheduling allowed a 50% dose reduction in sunitinib while maintaining comparable antitumor effects. This study shows that the therapeutic efficacy of combination therapy improves when proper dose-scheduling is applied. More importantly, optimal treatment regimes permit dose reductions in the angiogenesis inhibitor, which will likely reduce the side effects of combination therapy in the clinical setting. Our study provides important leads to optimize combination treatment in the clinical setting. PMID:25828633

  13. 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.

  14. Measurement of dose reductions for superficial x-rays backscattered from bone interfaces.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2008-09-07

    Accurate measurement and knowledge of dose delivered during superficial x-ray radiotherapy is required for patient dose assessment. Some tumours treated near the surface (within the first few centimetres) can have large posterior bone structures. This can cause perturbations to dose delivered due to changed backscatter contributions from the bony structure as compared to full water or tissue scattering conditions. Measured results have shown that up to 7.5% of Dmax reductions in dose can occur near the water/bone interface for 100 kVp, using 10 cm diameter field sizes when a 1 cm thick slab of bone is located at 2 cm depth. At smaller field sizes such as 2 cm diameter these values reduce to 2% for the same energy. Larger variations (up to 12.5% of maximum) have been seen at the phantom surface when the bone layer is directly behind the point of interest (within 0.5 mm) and smaller effects (up to 5% of maximum) at depths down to 5 cm. Interesting to note is the fact that for larger field sizes, an increase in percentage dose is found at the water/bone interface due to the production of low energy backscattered electrons similar to the effect found in lead. However, they are much smaller in magnitude and thus would not cause any significant dosimetric effects. In the case where large bony structures lie relatively close to the surface and the tissue above this region is being treated, a dosimeter such as radiochromic film can be used to estimate the dose reduction that may occur due to the changed backscatter conditions.

  15. Serum free IgE guided dose reduction of omalizumab: a case report.

    PubMed

    Gon, Yasuhiro; Ito, Reiko; Maruoka, Shuichiro; Mizumura, Kenji; Kozu, Yutaka; Hiranuma, Hisato; Iida, Yuko; Shikano, Sotaro; Hashimoto, Shu

    2017-01-01

    Omalizumab is a human IgG1 antibody against IgE used as a therapy for sever asthmatic patients with asthma. According to the guidelines of the Global Initiative for Asthma, omalizumab is an add-on drug at treatment step 5 that is used for severe asthma patients who are allergic to perennial allergens. The effects of omalizumab for severe asthma therapy have been validated in multiple clinical studies. However, the long-term effects of omalizumab on IgE production and possibility of resetting of administration dose of omalizumab remain unknown. The serum total and free IgE levels were measured over time in a 63-year-old female patient with allergic asthma who was administered 375 mg omalizumab biweekly for 36 months. Her symptoms did not worsen and clinical course remained favorable after reducing the dose to 375 mg per month. The serum free IgE levels temporarily increased following a dose reduction of omalizumab. The serum free IgE trough level temporarily increased at 4 weeks after capable to reduce the dosage; however, thereafter, the serum free IgE level decreased to desired levels (below 30 ng/mL). The present case shows the possibility of reducing the dose following the long-term use of omalizumab. Considering the high medical cost of omalizumab, the dose reduction may be a viable option. It may be useful to measure the serum free IgE level to appropriately identify patients in whom the dose can be reduced, and to carefully monitor the clinical course.

  16. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Early resistance training-induced increases in muscle cross-sectional area are concomitant with edema-induced muscle swelling.

    PubMed

    Damas, Felipe; Phillips, Stuart M; Lixandrão, Manoel E; Vechin, Felipe C; Libardi, Cleiton A; Roschel, Hamilton; Tricoli, Valmor; Ugrinowitsch, Carlos

    2016-01-01

    It has been proposed that skeletal muscle shows signs of resistance training (RT)-induced muscle hypertrophy much earlier (i.e., ~3-4 weeks of RT) than previously thought. We determined if early increases in whole muscle cross-sectional area (CSA) during a period of RT were concomitant with edematous muscle swelling and thus not completely attributable to hypertrophy. We analyzed vastus lateralis muscle ultrasound CSA images and their respective echo intensities (CSA-USecho) at the beginning (T1), in the 3rd week of RT (T2) and at the end (T3) of a 10-week RT period in ten untrained young men. Functional parameters [training volume (TV = load × reps × sets) and maximal voluntary contraction (MVC)] and muscle damage markers (myoglobin and interleukin-6) were also assessed. Muscle CSA increased significantly at T2 (~2.7%) and T3 (~10.4%) versus T1. Similarly, CSA-USecho increased at T2 (~17.2%) and T3 (~13.7%). However, when CSA-USecho was normalized to the increase in muscle CSA, only T2 showed a significantly higher USecho versus T1. Additionally, TV increased at T2 and T3 versus T1, but MVC increased only at T3. Myoglobin and Interleukin-6 were elevated at T2 versus T1, and myoglobin was also higher at T2 versus T3. We propose that early RT-induced increases in muscle CSA in untrained young individuals are not purely hypertrophy, since there is concomitant edema-induced muscle swelling, probably due to muscle damage, which may account for a large proportion of the increase. Therefore, muscle CSA increases (particularly early in an RT program) should not be labeled as hypertrophy without some concomitant measure of muscle edema/damage.

  18. 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, X John

    2016-03-08

    The purpose of this study was to characterize image quality and dose performance with GE CT iterative reconstruction techniques, adaptive statistical iterative recontruction (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

  19. Influence of dose reduction and iterative reconstruction on CT calcium scores: a multi-manufacturer dynamic phantom study.

    PubMed

    van der Werf, N R; Willemink, M J; Willems, T P; Greuter, M J W; Leiner, T

    2017-01-19

    To evaluate the influence of dose reduction in combination with iterative reconstruction (IR) on coronary calcium scores (CCS) in a dynamic phantom on state-of-the-art CT systems from different manufacturers. Calcified inserts in an anthropomorphic chest phantom were translated at 20 mm/s corresponding to heart rates between 60 and 75 bpm. The inserts were scanned five times with routinely used CCS protocols at reference dose and 40 and 80% dose reduction on four high-end CT systems. Filtered back projection (FBP) and increasing levels of IR were applied. Noise levels were determined. CCS, quantified as Agatston and mass scores, were compared to physical mass and scores at FBP reference dose. For the reference dose in combination with FBP, noise level variation between CT systems was less than 18%. Decreasing dose almost always resulted in increased CCS, while at increased levels of IR, CCS decreased again. The influence of IR on CCS was smaller than the influence of dose reduction. At reference dose, physical mass was underestimated 3-30%. All CT systems showed similar CCS at 40% dose reduction in combinations with specific reconstructions. For some CT systems CCS was not affected at 80% dose reduction, in combination with IR. This multivendor study showed that radiation dose reductions of 40% did not influence CCS in a dynamic phantom using state-of-the-art CT systems in combination with specific reconstruction settings. Dose reduction resulted in increased noise and consequently increased CCS, whereas increased IR resulted in decreased CCS.

  20. Imatinib dose reduction in patients with chronic myeloid leukemia in sustained deep molecular response.

    PubMed

    Cervantes, Francisco; Correa, Juan-Gonzalo; Pérez, Isabel; García-Gutiérrez, Valentín; Redondo, Sara; Colomer, Dolors; Jiménez-Velasco, Antonio; Steegmann, Juan-Luis; Sánchez-Guijo, Fermín; Ferrer-Marín, Francisca; Pereira, Arturo; Osorio, Santiago

    2017-01-01

    To determine whether a lower imatinib dose could minimize toxicity while maintaining the molecular response (MR), imatinib dose was reduced to 300 mg daily in 43 patients with chronic myeloid leukemia (CML) in sustained deep molecular response to first-line imatinib 400 mg daily. At the time of dose reduction, median duration of the deep response was 4.1 (interquartile range (IQR) 2.2-5.9) years; molecular response was MR(4), MR(4.5), and MR(5) of the international scale in 6, 28, and 9 patients, respectively. Toxicity grade was 1, 2, and 3 in 28, 8, and 1 patients, respectively; 6 patients underwent dose reduction without having side effects. With a median of 1.6 (IQR 0.7-3.2) years on imatinib 300 mg daily, only one patient lost the deep molecular response to MR(3). At the last follow-up, response was MR(3), MR(4), MR(4.5), and MR(5) in 1, 3, 9, and 30 patients, respectively. Toxicity improvement was observed in 23 (62.2 %) of the 37 patients with side effects, decreasing to grade 0 in 20 of them. All but one anemic patients improved (p = 0.01), the median Hb increase in this subgroup of patients being 1 g/dL. In CML patients with sustained deep response to the standard imatinib dose, reducing to 300 mg daily significantly improves tolerability and preserves efficacy.

  1. Reversal of neuromuscular blockade by sugammadex in laparoscopic bariatric surgery: In support of dose reduction.

    PubMed

    Badaoui, Rachid; Cabaret, Aurélie; Alami, Youssef; Zogheib, Elie; Popov, Ivan; Lorne, Emmanuel; Dupont, Hervé

    2016-02-01

    Sugammadex is the first molecule able to antagonize steroidal muscle relaxants with few adverse effects. Doses are adjusted to body weight and the level of neuromuscular blockade. Sleeve gastrectomy is becoming a very popular form of bariatric surgery. It requires deep muscle relaxation followed by complete and rapid reversal to decrease postoperative and especially post-anaesthetic morbidity. Sugammadex is therefore particularly indicated in this setting. The objective of this study was to evaluate the deep neuromuscular blockade reversal time after administration of various doses of sugammadex (based on real weight or at lower doses). Secondary endpoints were the interval between the sugammadex injection and extubation and transfer from the operating room to the recovery room. We then investigated any complications observed in the recovery room. This pilot, prospective, observational, clinical practice evaluation study was conducted in the Amiens University Hospital. Neuromuscular blockade was induced by rocuronium. At the end of the operation, deep neuromuscular blockade was reversed by sugammadex at the dose of 4mg/kg. Sixty-four patients were included: 31 patients received sugammadex at a dosage based on their real weight (RW) and 33 patients received a lower dose (based on ideal weight [IW]). For identical rocuronium doses calculated based on IBW, sugammadex doses were significantly lower in the IW group: 349 (± 65) mg versus 508 (± 75) mg (P<0.0001). Despite this dose reduction, neuromuscular blockade reversal took 115 (± 69) s in the IW group versus 87 (± 40) s in the RW group, but with no significant difference between the two groups (P=0.08). The intervals between injection of sugammadex and extubation (P=0.07) and transfer from the operating room to the recovery room (P=0.68) were also non-significantly longer in the IW group. The mean dose of sugammadex used by anaesthetists in the IW group was 4mg/kg of ideal weight increased by 35% to 50% (n

  2. Pulsed electromagnetic fields dosing impacts postoperative pain in breast reduction patients.

    PubMed

    Taylor, Erin M; Hardy, Krista L; Alonso, Amanda; Pilla, Arthur A; Rohde, Christine H

    2015-01-01

    Pulsed electromagnetic fields (PEMF) reduce postoperative pain and narcotic requirements in breast augmentation, reduction, and reconstruction patients. PEMF enhances both calmodulin-dependent nitric oxide and/or cyclic guanosine monophosphate signaling and phosphodiesterase activity, which blocks cyclic guanosine monophosphate. The clinical effect of these competing responses on PEMF dosing is not known. Two prospective, nonrandomized, active cohorts of breast reduction patients, with 15 min PEMF per 2 h; "Q2 (active)", and 5 min PEMF per 20 min; "5/20 (active)", dosing regimens were added to a previously reported double-blind clinical study wherein 20 min PEMF per 4 h, "Q4 (active)", dosing significantly accelerated postoperative pain reduction compared with Q4 shams. Postoperative visual analog scale pain scores and narcotic use were compared with results from the previous study. Visual analog scale scores at 24 h were 43% and 35% of pain at 1 h in the Q4 (active) and Q2 (active) cohorts, respectively (P < 0.01). Pain at 24 h in the 5/20 (active) cohort was 87% of pain at 1 h, compared with 74% in the Q4 (sham) cohort (P = 0.451). Concomitantly, narcotic usage in the 5/20 (active) and Q4 (sham) cohorts was not different (P = 0.478), and 2-fold higher than the Q4 (active) and Q2 (active) cohorts (P < 0.02). This prospective study shows Q4/Q2, but not 5/20 PEMF dosing, accelerated postoperative pain reduction compared with historical shams. The 5/20 (active) regimen increases NO 4-fold faster than the Q4 (active) regimen, possibly accelerating phosphodiesterase inhibition of cyclic guanosine monophosphate sufficiently to block the PEMF effect. This study helps define the dosing limits of clinically useful PEMF signals. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. 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.

  4. Radiation dose reduction during transjugular intrahepatic portosystemic shunt implantation using a new imaging technology.

    PubMed

    Spink, C; Avanesov, M; Schmidt, T; Grass, M; Schoen, G; Adam, G; Bannas, P; Koops, A

    2017-01-01

    To compare patient radiation dose in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) implantation before and after an imaging-processing technology upgrade. In our retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), total fluoroscopy time and contrast agent were collected from an age- and BMI-matched collective of 108 patients undergoing TIPS implantation. 54 procedures were performed before and 54 after the technology upgrade. Mean values were calculated and compared using two-tailed t-tests. Two blinded, independent readers assessed DSA image quality using a four-rank likert scale and the Wilcoxcon test. The new technology demonstrated a significant reduction of 57% of mean DAP (402.8 vs. 173.3Gycm(2), p<0.001) and a significant reduction of 58% of mean AK (1.7 vs. 0.7Gy, p<0.001) compared to the precursor technology. Time of fluoroscopy (26.4 vs. 27.8min, p=0.45) and amount of contrast agent (109.4 vs. 114.9ml, p=0.62) did not differ significantly between the two groups. The DSA image quality of the new technology was not inferior (2.66 vs. 2.77, p=0.56). In our study the new imaging technology halved radiation dose in patients undergoing TIPS maintaining sufficient image quality without a significant increase in radiation time or contrast consumption. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. Characterization of a lead breast shielding for dose reduction in computed tomography*

    PubMed Central

    Correia, Paula Duarte; Granzotti, Cristiano Roberto Fabri; Santos, Yago da Silva; Brochi, Marco Aurelio Corte; de Azevedo-Marques, Paulo Mazzoncini

    2014-01-01

    Objective Several studies have been published regarding the use of bismuth shielding to protect the breast in computed tomography (CT) scans and, up to the writing of this article, only one publication about barium shielding was found. The present study was aimed at characterizing, for the first time, a lead breast shielding. Materials and Methods The percentage dose reduction and the influence of the shielding on quantitative imaging parameters were evaluated. Dose measurements were made on a CT equipment with the aid of specific phantoms and radiation detectors. A processing software assisted in the qualitative analysis evaluating variations in average CT number and noise on images. Results The authors observed a reduction in entrance dose by 30% and in CTDIvol by 17%. In all measurements, in agreement with studies in the literature, the utilization of cotton fiber as spacer object reduced significantly the presence of artifacts on the images. All the measurements demonstrated increase in the average CT number and noise on the images with the presence of the shielding. Conclusion As expected, the data observed with the use of lead shielding were of the same order as those found in the literature about bismuth shielding. PMID:25741089

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Cardiovascular CT angiography in neonates and children: image quality and potential for radiation dose reduction with iterative image reconstruction techniques.

    PubMed

    Tricarico, Francesco; Hlavacek, Anthony M; Schoepf, U Joseph; Ebersberger, Ullrich; Nance, John W; Vliegenthart, Rozemarijn; Cho, Young Jun; Spears, J Reid; Secchi, Francesco; Savino, Giancarlo; Marano, Riccardo; Schoenberg, Stefan O; Bonomo, Lorenzo; Apfaltrer, Paul

    2013-05-01

    To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose reductions. Forty neonates and children underwent low radiation CTA with or without ECG synchronisation. Data were reconstructed with FBP, IRIS and SAFIRE. For ECG-synchronised studies, half-dose image acquisitions were simulated. Signal noise was measured and IQ graded. Effective dose (ED) was estimated. Mean absolute and relative image noise with IRIS and full-dose SAFIRE was lower than with FBP (P < 0.001), while SNR and CNR were higher (P < 0.001). Image noise was also lower and SNR and CNR higher in half-dose SAFIRE studies compared with full-and half-dose FBP studies (P < 0.001). IQ scores were higher for IRIS, full-dose SAFIRE and half-dose SAFIRE than for full-dose FBP and higher for half-dose SAFIRE than for half-dose FBP (P < 0.05). Median weight-specific ED was 0.3 mSv without and 1.36 mSv with ECG synchronisation. The estimated ED of half-dose SAFIRE studies was 0.68 mSv. IR improves image noise, SNR, CNR and subjective IQ compared with FBP in low-radiation-dose paediatric CTA and allows further dose reductions without compromising diagnostic IQ. • Iterative reconstruction techniques significantly improve non-invasive cardiovascular CT in children. • Using half traditional radiation dose image quality is higher with iterative reconstruction. • Iterative reconstruction techniques may allow further radiation reductions in paediatric cardiovascular CT.

  13. 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.

  14. Impact of view reduction in CT on radiation dose for patients

    NASA Astrophysics Data System (ADS)

    Parcero, E.; Flores, L.; Sánchez, M. G.; Vidal, V.; Verdú, G.

    2017-08-01

    Iterative methods have become a hot topic of research in computed tomography (CT) imaging because of their capacity to resolve the reconstruction problem from a limited number of projections. This allows the reduction of radiation exposure on patients during the data acquisition. The reconstruction time and the high radiation dose imposed on patients are the two major drawbacks in CT. To solve them effectively we adapted the method for sparse linear equations and sparse least squares (LSQR) with soft threshold filtering (STF) and the fast iterative shrinkage-thresholding algorithm (FISTA) to computed tomography reconstruction. The feasibility of the proposed methods is demonstrated numerically.

  15. Dose reduction in abdominal computed tomography: intraindividual comparison of image quality of full-dose standard and half-dose iterative reconstructions with dual-source computed tomography.

    PubMed

    May, Matthias S; Wüst, Wolfgang; Brand, Michael; Stahl, Christian; Allmendinger, Thomas; Schmidt, Bernhard; Uder, Michael; Lell, Michael M

    2011-07-01

    We sought to evaluate the image quality of iterative reconstruction in image space (IRIS) in half-dose (HD) datasets compared with full-dose (FD) and HD filtered back projection (FBP) reconstruction in abdominal computed tomography (CT). To acquire data with FD and HD simultaneously, contrast-enhanced abdominal CT was performed with a dual-source CT system, both tubes operating at 120 kV, 100 ref.mAs, and pitch 0.8. Three different image datasets were reconstructed from the raw data: Standard FD images applying FBP which served as reference, HD images applying FBP and HD images applying IRIS. For the HD data sets, only data from 1 tube detector-system was used. Quantitative image quality analysis was performed by measuring image noise in tissue and air. Qualitative image quality was evaluated according to the European Guidelines on Quality criteria for CT. Additional assessment of artifacts, lesion conspicuity, and edge sharpness was performed. : Image noise in soft tissue was substantially decreased in HD-IRIS (-3.4 HU, -22%) and increased in HD-FBP (+6.2 HU, +39%) images when compared with the reference (mean noise, 15.9 HU). No significant differences between the FD-FBP and HD-IRIS images were found for the visually sharp anatomic reproduction, overall diagnostic acceptability (P = 0.923), lesion conspicuity (P = 0.592), and edge sharpness (P = 0.589), while HD-FBP was rated inferior. Streak artifacts and beam hardening was significantly more prominent in HD-FBP while HD-IRIS images exhibited a slightly different noise pattern. Direct intrapatient comparison of standard FD body protocols and HD-IRIS reconstruction suggest that the latest iterative reconstruction algorithms allow for approximately 50% dose reduction without deterioration of the high image quality necessary for confident diagnosis.

  16. Effects of low-dose mindfulness-based stress reduction (MBSR-ld) on working adults.

    PubMed

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

    2009-06-01

    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 adults to determine if results similar to those obtained in traditional MBSR could be demonstrated. Participants were randomized into MBSR-ld and wait-list control groups. Self-reported perceived stress, sleep quality, and mindfulness were measured at the beginning and end of the 6-week intervention. Salivary cortisol was assessed weekly. Significant reductions in perceived stress (p = .0025) and increases in mindfulness (p = .0149) were obtained for only the MBSR-ld group (n = 22). Scores on the global measure of sleep improved for the MBSR-ld group (p = .0018) as well as for the control group (p = .0072; n = 20). Implications and future research are discussed.

  17. Dose reduction in CT urography and vasculature phantom studies using model-based iterative reconstruction.

    PubMed

    Page, Leland; Wei, Wei; Kundra, Vikas; Rong, John

    2016-11-08

    To evaluate the feasibility of radiation dose reduction using model-based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue-equivalent CT dose phantom was scanned using a 64-channel CT scan-ner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index (CTDIvol) of 24 mGy. The scans were repeated using reduced scan techniques to achieve lower radiation doses down to 0.8 mGy. The images were reconstructed using filtered back-projection (FBP) and model-based iterative reconstruction (MBIR). The noise and contrast-to-noise ratio (CNR) was measured for each contrast object. Comparisons between the two reconstruction methods at different dose levels were evaluated using a factorial design. At each CTDIvol the measured image noise was lower using MBIR compared to FBP (p < 0.0001). At low doses, the percent change in measured image noise between FBP and MBIR was larger. For the 12 mm object simulating a ureter or large vessel with an HU of 600, the measured CNR using MBIR at a CTDIvol of 1.7 mGy was greater than the CNR of FBP at a CTIDvol of 24 mGy (p < 0.0001). For the 5 mm object simulating a medium-sized vessel with a HU of 250, the mea-sured CNR using MBIR at a CTDIvol of 1.7 mGy was equivalent to that of FBP at a CTDIvol of 24 mGy. For the 2 mm, 100 HU object simulating a small vessel, the measured CNR using MBIR at a CTDIvol of 1.7 mGy was equivalent to that of FBP at a CTDIvol of 24 mGy. Low-dose (3.6 mGy) CT imaging of vasculature and ureter phantoms using MBIR results in similar noise and CNR compared to FBP at approximately one-sixth the dose. This suggests that, using MBIR, a one milliSievert exam of the ureters and vasculature may be clinically possible whilst still maintaining adequate

  18. X-ray dose reduction through adaptive exposure in fluoroscopic imaging.

    PubMed

    Burion, Steve; Funk, Tobias

    2011-09-11

    current implementation, the adaptive exposure requires user interaction (Figure 3). However, in the future, the adaptive exposure will be real time and fully automatic. We have performed experiments with an anthropomorphic phantom and compared measured radiation dose with and without adaptive exposure using a dose area product (DAP) meter. In the experiment presented here, we find a dose reduction of 30%.

  19. Automatic selection of tube potential for radiation dose reduction in CT: A general strategy

    SciTech Connect

    Yu Lifeng; Li Hua; Fletcher, Joel G.; McCollough, Cynthia H.

    2010-01-15

    Purpose: To optimize radiation dose efficiency in CT while maintaining image quality, it is important to select the optimal tube potential. The selection of optimal tube potential, however, is highly dependent on patient size and diagnostic task. The purpose of this work was to develop a general strategy that allows for automatic tube potential selection for each individual patient and each diagnostic task. Methods: The authors propose a general strategy that allows automatic adaptation of the tube potential as a function of patient size and diagnostic task, using a novel index of image quality, ''iodine contrast to noise ratio with a noise constraint (iCNR{sub N}C),'' to characterize the different image quality requirements by various clinical applications. The relative dose factor (RDF) at each tube potential to achieve a target image quality was then determined as a function of patient size and the noise constraint parameter. A workflow was developed to automatically identify the optimal tube potential that is both dose efficient and practically feasible, incorporating patient size and diagnostic task. An experimental study using a series of semianthropomorphic thoracic phantoms was used to demonstrate how the proposed general strategy can be implemented and how the radiation dose reduction achievable by the tube potential selection depends on phantom sizes and noise constraint parameters. Results: The proposed strategy provides a flexible and quantitative way to select the optimal tube potential based on the patient size and diagnostic task. The noise constraint parameter {alpha} can be adapted for different clinical applications. For example, {alpha}=1 for noncontrast routine exams; {alpha}=1.1-1.25 for contrast-enhanced routine exams; and {alpha}=1.5-2.0 for CT angiography. For the five thoracic phantoms in the experiment, when {alpha}=1, the optimal tube potentials were 80, 100, 100, 120, 120, respectively. The corresponding RDFs (relative to 120 kV) were 78

  20. ALARA: Impact of Practice Quality Improvement Initiative on Dose Reduction in Pediatric Voiding Cystourethrogram.

    PubMed

    Jaju, Alok; Shaw, Hillary L; Don, Steven; Bowling, Rebecca Hulett; Hildebolt, Charles F

    2015-10-01

    This practice quality improvement study of pediatric voiding cystourethrogram (VCUG) investigated the adequacy of substituting last-image capture for digital-spot images and dose reduction when this substitution was implemented and determined correlations between dose-area products (DAPs), patient ages, and fluoroscopy times. The study consisted of three phases: phase 1 documented baseline data and evaluated diagnostic accuracy between last-image capture and digital-spot images. Phase 2 documented the change in dose after substituting last-image capture for digital-spot images. Phase 3 measured doses 3 years later. Each phase-1 VCUG study was segregated into two image sets: last-image capture and digital-spot images. Three radiologists graded vesicoureteral reflux on each side using the international grading scale. Weighted kappa statistics assessed grading differences between image sets. Patient age, fluoroscopy time, and DAP were assessed with parametric and nonparametric statistics. Seventy-seven, 65, and 71 VCUGs were assessed for phases 1, 2, and 3, respectively. Weighted κ = 0.94-0.99 indicated nearly perfect agreement between last-image-capture and digital-spot-image interpretations. For phase 2, last-image capture was substituted for digital-spot images for early-filling and voiding images. DAP decreased for all three radiologists (p ≤ 0.01). Five of six (83%) correlations between DAP and age were higher than the correlations between DAP and fluoroscopy time. The dose remained significantly lower in phase 3. This project changed practice by substituting last-image capture for digital-spot images without affecting vesicoureteral reflux grading while reducing radiation exposure. Monitoring DAP is a better assessment of radiation exposure than is fluoroscopy time.

  1. Radiation Dose Reduction during Uterine Fibroid Embolization Using an Optimized Imaging Platform.

    PubMed

    Kohlbrenner, Ryan; Kolli, K Pallav; Taylor, Andrew G; Kohi, Maureen P; Lehrman, Evan D; Fidelman, Nicholas; Conrad, Miles; LaBerge, Jeanne M; Kerlan, Robert K; Gould, Robert

    2017-08-01

    To assess radiation dose reduction during uterine fibroid embolization (UFE) using an optimized angiographic processing and acquisition platform. Radiation dose data for 70 women (mean age, 46 y; range, 34-67 y) who underwent UFE were retrospectively analyzed. Twenty-one patients underwent UFE using the baseline fluoroscopic and angiographic image acquisition platform, and 49 underwent UFE after implementing an optimized imaging platform in otherwise identical angiography suites. Cumulative kerma-area product (CKAP), cumulative air kerma (CAK), total fluoroscopy time, and image exposure number were collected for each procedure. Image quality was assessed by 3 interventional radiologists blinded to the platform used for image acquisition and processing. Patients undergoing UFE using the new x-ray fluoroscopy platform had significantly lower CKAP and CAK indicators than patients for whom baseline settings were used. Mean CKAP decreased by 60% from 438.5 Gy · cm(2) (range, 180.3-1,081.1 Gy · cm(2)) to 175.2 Gy · cm(2) (range, 47.1-757.0 Gy · cm(2); P < .0001). Mean CAK decreased by 45% from 2,034.2 mGy (range, 699.3-5,056.0 mGy) to 1,109.8 mGy (range, 256.6-4,513.6 mGy; P = .001). No degradation of image quality was identified through qualitative evaluation. Significant reduction in patient radiation dose indicators can be achieved with use of an optimized image acquisition and processing platform. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

  2. Characteristics of Movement-Induced Dose Reduction in Target Volume: A Comparison Between Photon and Proton Beam Treatment

    SciTech Connect

    Yoon, Myonggeun; Shin, Dongho; Kwak, Jungwon; Park, Soah; Lim, Young Kyung; Kim, Dongwook; Park, Sung Yong Lee, Se Byeong; Shin, Kyung Hwan; Kim, Tae Hyun; Cho, Kwan Ho

    2009-10-01

    We compared the main characteristics of movement-induced dose reduction during photon and proton beam treatment, based on an analysis of dose-volume histograms. To simulate target movement, a target contour was delineated in a scanned phantom and displaced by 3 to 20 mm. Although the dose reductions to the target in the 2 treatment systems were similar for transverse (perpendicular to beam direction) target motion, they were completely different for longitudinal (parallel to beam direction) target motion. While both modalities showed a relationship between the degree of target shift and the reduction in dose coverage, dose reduction showed a strong directional dependence in proton beam treatment. Clinical simulation of target movement for a prostate cancer patient showed that, although coverage and conformity indices for a 6-mm lateral movement of the prostate were reduced by 9% and 16%, respectively, for proton beam treatment, they were reduced by only 1% and 7%, respectively, for photon treatment. This difference was greater for a 15-mm target movement in the lateral direction, which lowered the coverage and conformity indices by 34% and 54%, respectively, for proton beam treatment, but changed little during photon treatment. In addition, we found that the equivalent uniform dose (EUD) and homogeneity index show similar characteristics during target movement. These results suggest that movement-induced dose reduction differs significantly between photon and proton beam treatment. Attention should be paid to the target margin in proton beam treatment due to the distinct characteristics of heavy ion beams.

  3. Novel X-ray image noise reduction technology reduces patient radiation dose while maintaining image quality in coronary angiography.

    PubMed

    Ten Cate, T; van Wely, M; Gehlmann, H; Mauti, M; Camaro, C; Reifart, N; Suryapranata, H; de Boer, M J

    2015-11-01

    The consequences of high radiation dose for patient and staff demand constant improvements in X-ray dose reduction technology. This study assessed non-inferiority of image quality and quantified patient dose reduction in interventional cardiology for an anatomy-specific optimised cine acquisition chain combined with advanced real-time image noise reduction algorithms referred to as 'study cine', compared with conventional angiography. Fifty patients underwent two coronary angiographic acquisitions: one with advanced image processing and optimised exposure system settings to enable dose reduction (study cine) and one with standard image processing and exposure settings (reference cine). The image sets of 39 patients (18 females, 21 males) were rated by six experienced independent reviewers, blinded to the patient and image characteristics. The image pairs were randomly presented. Overall 85 % of the study cine images were rated as better or equal quality compared with the reference cine (95 % CI 0.81-0.90). The median dose area product per frame decreased from 55 to 26 mGy.cm(2)/frame (53 % reduction, p < 0.001). This study demonstrates that the novel X-ray imaging technology provides non-inferior image quality compared with conventional angiographic systems for interventional cardiology with a 53 % patient dose reduction.

  4. 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.

  5. Preliminary validation of a new methodology for estimating dose reduction protocols in neonatal chest computed radiographs

    NASA Astrophysics Data System (ADS)

    Don, Steven; Whiting, Bruce R.; Hildebolt, Charles F.; Sehnert, W. James; Ellinwood, Jacquelyn S.; Töpfer, Karin; Masoumzadeh, Parinaz; Kraus, Richard A.; Kronemer, Keith A.; Herman, Thomas; McAlister, William H.

    2006-03-01

    The risk of radiation exposure is greatest for pediatric patients and, thus, there is a great incentive to reduce the radiation dose used in diagnostic procedures for children to "as low as reasonably achievable" (ALARA). Testing of low-dose protocols presents a dilemma, as it is unethical to repeatedly expose patients to ionizing radiation in order to determine optimum protocols. To overcome this problem, we have developed a computed-radiography (CR) dose-reduction simulation tool that takes existing images and adds synthetic noise to create realistic images that correspond to images generated with lower doses. The objective of our study was to determine the extent to which simulated, low-dose images corresponded with original (non-simulated) low-dose images. To make this determination, we created pneumothoraces of known volumes in five neonate cadavers and obtained images of the neonates at 10 mR, 1 mR and 0.1 mR (as measured at the cassette plate). The 10-mR exposures were considered "relatively-noise-free" images. We used these 10 mR-images and our simulation tool to create simulated 0.1- and 1-mR images. For the simulated and original images, we identified regions of interest (ROI) of the entire chest, free-in-air region, and liver. We compared the means and standard deviations of the ROI grey-scale values of the simulated and original images with paired t tests. We also had observers rate simulated and original images for image quality and for the presence or absence of pneumothoraces. There was no statistically significant difference in grey-scale-value means nor standard deviations between simulated and original entire chest ROI regions. The observer performance suggests that an exposure >=0.2 mR is required to detect the presence or absence of pneumothoraces. These preliminary results indicate that the use of the simulation tool is promising for achieving ALARA exposures in children.

  6. Whole-body PET/CT studies with lowered ¹⁸F-FDG doses: the influence of body mass index in dose reduction.

    PubMed

    Sánchez-Jurado, Raúl; Devis, Manuel; Sanz, Rut; Aguilar, Jose Enrique; del Puig Cózar, Maria; Ferrer-Rebolleda, Jose

    2014-03-01

    The administered dose of (18)F-FDG can be greatly reduced using body mass index (BMI) instead of the patient's weight, without diminishing image quality. We have focused on reducing the administered dose while maintaining the acquisition time and have developed dosing-based algorithms using BMI. We conducted a prospective dose-adjustment research study with more than 1,800 patients undergoing time-of-flight PET/CT. From January 2009 to October 2010 we recruited 1,000 patients, of whom 180 were randomly selected to create the control group. The treatment group was created by selecting 180 new subjects from a total of 800 recruited from January to December 2011. The control group was administered a body weight-calculated dose of 5.55-7.4 MBq/kg. The treatment group was administered a BMI-calculated dose of 6.85-11.1 MBq/BMI. Each group was divided into 5 subgroups according to BMI classification (underweight, normal weight, overweight, obese, and morbidly obese). All scans were acquired with a time-of-flight PET/CT scanner and were evaluated in a masked manner by 2 nuclear medicine physicians. Evaluation of images was purely qualitative, with visual scoring of image quality from 1 to 3 (high to low). These data were analyzed for statistical significance. Dosimetric measures of patients' emitted radiation were taken at the surface and at a distance of 0.5 m and 1 m to compare the groups. The readings of PET staff dosimeters were evaluated during this period and analyzed. A reduction of between 9% and 22% in administered dose per patient was achieved for the BMI-derived dose group with respect to the body weight-calculated dose group. In addition, an effective dose reduction of 56% and 12.5% for patients and staff, respectively, was achieved. The cost per study was therefore reduced while diagnostic image quality was maintained or even improved in most cases. BMI-calculated doses, which are often lower than strictly weight-based doses, can be administered while

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

    PubMed

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

    2013-03-01

    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. 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. Based on the phantom and pediatric patient fan-beam CT data, it is demonstrated that EST reconstructions with the lowest scanner flux setting of 39 m

  8. Aqueous and Methanolic Extracts of Caulerpa mexicana Suppress Cell Migration and Ear Edema Induced by Inflammatory Agents

    PubMed Central

    Bitencourt, Mariana Angelica Oliveira; Dantas, Gracielle Rodrigues; Lira, Daysianne Pereira; Barbosa-Filho, Jose Maria; de Miranda, George Emmanuel Cavalcanti; de Oliveira Santos, Barbara Viviana; Souto, Janeusa Trindade

    2011-01-01

    The regulation of the inflammatory response is essential to maintaining homeostasis. Several studies have investigated new drugs that may contribute to avoiding or minimizing excessive inflammatory process. The aim of this study was to evaluate the effect of extracts of green algae Caulerpa mexicana on models inflammation. In mice, the inflammatory peritonitis model is induced by zymosan. Previous treatment of mice with aqueous and methanolic extracts of C. mexicana was able to suppress the cell migration to the peritoneal cavity, in a time-dependent but not in a dose-dependent manner. The treatment of mice with C. mexicana extracts also decreased the xylene-induced ear edema, exerting strong inhibitory leukocyte migration elicited by zymosan into the air pouch. We concluded that administration of the extracts resulted in a reduction of cell migration to different sites as well as a decrease in edema formation induced by chemical irritants. This study demonstrates for the first time the anti-inflammatory effect of aqueous and methanolic extracts from the green marine algae Caulerpa mexicana. PMID:21892348

  9. Aqueous and methanolic extracts of Caulerpa mexicana suppress cell migration and ear edema induced by inflammatory agents.

    PubMed

    Bitencourt, Mariana Angelica Oliveira; Dantas, Gracielle Rodrigues; Lira, Daysianne Pereira; Barbosa-Filho, Jose Maria; de Miranda, George Emmanuel Cavalcanti; Santos, Barbara Viviana de Oliveira; Souto, Janeusa Trindade

    2011-01-01

    The regulation of the inflammatory response is essential to maintaining homeostasis. Several studies have investigated new drugs that may contribute to avoiding or minimizing excessive inflammatory process. The aim of this study was to evaluate the effect of extracts of green algae Caulerpa mexicana on models inflammation. In mice, the inflammatory peritonitis model is induced by zymosan. Previous treatment of mice with aqueous and methanolic extracts of C. mexicana was able to suppress the cell migration to the peritoneal cavity, in a time-dependent but not in a dose-dependent manner. The treatment of mice with C. mexicana extracts also decreased the xylene-induced ear edema, exerting strong inhibitory leukocyte migration elicited by zymosan into the air pouch. We concluded that administration of the extracts resulted in a reduction of cell migration to different sites as well as a decrease in edema formation induced by chemical irritants. This study demonstrates for the first time the anti-inflammatory effect of aqueous and methanolic extracts from the green marine algae Caulerpa mexicana.

  10. Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems

    PubMed Central

    Sakurai, T; Kawamata, R; Kozai, Y; Kaku, Y; Nakamura, K; Saito, M; Wakao, H; Kashima, I

    2010-01-01

    Objectives The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction. Methods Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose. Results The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC. Conclusions The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction. PMID:20395461

  11. Evaluation of dose reduction and image quality in CT colonography: comparison of low-dose CT with iterative reconstruction and routine-dose CT with filtered back projection.

    PubMed

    Nagata, Koichi; Fujiwara, Masanori; Kanazawa, Hidenori; Mogi, Tomohiro; Iida, Nao; Mitsushima, Toru; Lefor, Alan T; Sugimoto, Hideharu

    2015-01-01

    To prospectively evaluate the radiation dose and image quality comparing low-dose CT colonography (CTC) reconstructed using different levels of iterative reconstruction techniques with routine-dose CTC reconstructed with filtered back projection. Following institutional ethics clearance and informed consent procedures, 210 patients underwent screening CTC using automatic tube current modulation for dual positions. Examinations were performed in the supine position with a routine-dose protocol and in the prone position, randomly applying four different low-dose protocols. Supine images were reconstructed with filtered back projection and prone images with iterative reconstruction. Two blinded observers assessed the image quality of endoluminal images. Image noise was quantitatively assessed by region-of-interest measurements. The mean effective dose in the supine series was 1.88 mSv using routine-dose CTC, compared to 0.92, 0.69, 0.57, and 0.46 mSv at four different low doses in the prone series (p < 0.01). Overall image quality and noise of low-dose CTC with iterative reconstruction were significantly improved compared to routine-dose CTC using filtered back projection. The lowest dose group had image quality comparable to routine-dose images. Low-dose CTC with iterative reconstruction reduces the radiation dose by 48.5 to 75.1% without image quality degradation compared to routine-dose CTC with filtered back projection. • Low-dose CTC reduces radiation dose ≥ 48.5% compared to routine-dose CTC. • Iterative reconstruction improves overall CTC image quality compared with FBP. • Iterative reconstruction reduces overall CTC image noise compared with FBP. • Automated exposure control with iterative reconstruction is useful for low-dose CTC.

  12. 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).

  13. 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.

  14. 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

  15. Rectal and bladder dose reduction with the addition of intravaginal balloons to vaginal packing in intracavitary brachytherapy for cervical cancer.

    PubMed

    Eng, T Y; Patel, A J; Ha, C S

    2016-01-01

    The use of intravaginal Foley balloons in addition to conventional packing during high-dose-rate (HDR) tandem and ovoids intracavitary brachytherapy (ICBT) is a means to improve displacement of organs at risk, thus reducing dose-dependent complications. The goal of this project was to determine the reduction in dose achieved to the bladder and rectum with intravaginal Foley balloons with CT-based planning and to share our packing technique. One hundred and six HDR-ICBT procedures performed for 38 patients were analyzed for this report. An uninflated Foley balloon was inserted into the vagina above and below the tandem flange separately and secured in place with vaginal packing. CT images were then obtained with both inflated and deflated Foley balloons. Plan optimization occurred and dose volume histogram data were generated for the bladder and rectum. Maximum dose to 0.1, 1.0, and 2.0 cm(3) volumes for the rectum and bladder were analyzed and compared between inflated and deflated balloons using parametric statistical analysis. Inflation of intravaginal balloons allowed significant reduction of dose to the bladder and rectum. Amount of reduction was dependent on the anatomy of the patient and the placement of the balloons. Displacement of the organs at risk by the balloons allowed an average of 7.2% reduction in dose to the bladder (D0.1 cm(3)) and 9.3% to the rectum (D0.1 cm(3)) with a maximum reduction of 41% and 43%, respectively. For patients undergoing HDR-ICBT, a significant dose reduction to the bladder and rectum could be achieved with further displacement of these structures using intravaginal Foley balloons in addition to conventional vaginal packing. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  16. 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.

  17. The utilisation of the cardiovascular automated radiation reduction X-ray system (CARS) in the cardiac catheterisation laboratory aids in the reduction of the patient radiation dose.

    PubMed

    Didier, Romain; Magalhaes, Marco A; Koifman, Edward; Leven, Florent; Castellant, Philippe; Boschat, Jacques; Jobic, Yannic; Kiramijyan, Sarkis; Nicol, Pierre-Philippe; Gilard, Martine

    2016-10-10

    The radiation exposure resulting from cardiovascular procedures may increase the risk of cancer, and/or cause skin injury. Whether the novel cardiovascular automated radiation reduction X-ray system (CARS) can help reduce the patient radiation dose in daily clinical practice remains unknown. The aim of this study was to evaluate the reduction in patient radiation dose with the use of CARS in the cardiac catheterisation laboratory (CCL). This study retrospectively analysed 1,403 consecutives patients who underwent a cardiac catheterisation with coronary angiography (CA) and/or a percutaneous coronary intervention (PCI) in the Brest University Hospital over the course of one year. Patient radiation doses (dose area product and air kerma) were collected and compared between the CCL with (new CCL) and without (control CCL) CARS. Additionally, the patient radiation doses according to femoral versus radial access, procedural complexity and body mass index were compared. The radiation lesion position on the skin was assessed by automatically optimising the X-ray source to image distance (SID) and subsequently generating a radiation Dose-Map for those procedures exceeding 3 Gray of exposure. Overall, 447 patients underwent procedures in the control CCL and 956 in the new CCL. Baseline patient and procedural characteristics were similar between the two groups, with the exception of male gender and primary PCI, which were more prevalent in the new CCL group. Compared to the control CCL, the utilisation of the CARS in the new CCL resulted in a reduction of dose area product by 46% for CA, 56% for PCI alone and 54% for CA and PCI during the same procedure. Of note, radial access generated a higher radiation dose than femoral access (p<0.001). In this study, seven patients had an air kerma exceeding 3 Gray; however, only one patient had a skin dose greater than 3 Gray. The utilisation of the CARS resulted in a significant reduction in patient radiation doses compared to the

  18. Quantifying potential reduction in contrast dose with monoenergetic images synthesized from duallayer detector spectral CT.

    PubMed

    Tsang, Derek S; Merchant, Thomas E; Merchant, Sophie E; Smith, Hanna; Yagil, Yoad; Hua, Chia-Ho

    2017-07-27

    To estimate the potential dose reduction in iodinated contrast when interpreting monoenergetic images from spectral CT. 51 pediatric patients received contrast-enhanced CT simulation for radiation therapy using a single-source, dual-layer detector spectral CT. The contrast-to-noise ratios (CNR) of blood vessels were measured relative to surrounding soft tissue. CNRs on monoenergetic 40-70 keV images were compared with polychromatic 120 kVp images. To compare with in vivo results, a phantom with iodine inserts (2-20 mg/mL concentration) was scanned and CNRs were calculated relative to water background. Monoenergetic keV and body site had significant effects on CNR ratio (P < 0.0001). Across all body sites, the mean CNR ratio (monoenergetic/polychromatic CNR) was 3.3 (20(th) percentile [%20] 2.6), 2.4 (%20 2.1), 1.7 (%20 1.5), 1.2 (%20 1.0) for 40, 50, 60 and 70 keV images, respectively. Image noise was highest at 40 keV and lowest at 70 keV. Phantom measurements indicated that the same CNR as 120 kVp images can be achieved with a 4.0-fold lower iodine concentration on 40 keV images and 2.5-fold lower on 50 keV images. 50 keV monoenergetic images provided the best balance of improved CNR on all studies (mean 2.4-fold increase in vivo) for enhancing vessels versus image noise. A 50% reduction in contrast dose on a 50 keV image should maintain comparable or better CNR as compared with polychromatic CT in over 80% of CT studies. Advances in Knowledge: Use of a novel, single-source, dual-layer detector spectral CT scanner to improve visualization of contrast-enhanced blood vessels will reduce the amount of iodinated contrast required for radiation oncology treatment planning.

  19. Flexible lateral isocenter: A novel mechanical functionality contributing to dose reduction in neurointerventional procedures.

    PubMed

    Borota, Ljubisa; Patz, Andreas

    2017-01-01

    Aim of the study A new functionality that enables vertical mobility of the lateral arm of a biplane angiographic machine is referred to as the flexible lateral isocenter. The aim of this study was to analyze the impact of the flexible lateral isocenter on the air-kerma rate under experimental conditions. Material and methods An anthropomorphic head-and-chest phantom with anteroposterior (AP) diameter of the chest varying from 22 cm to 30 cm simulated human bodies of different body constitutions. The angulation of the AP arm in the sagittal plane varied from 35 degrees to 55 degrees for each AP diameter. The air-kerma rate (mGy/min) values were read from the system dose display in two settings for each angle: flexible lateral isocenter and fixed lateral isocenter. Results The air-kerma rate was significantly lower for all AP diameters of the chest of the phantom when the flexible lateral isocenter was used: (a) For 22 cm, the p value was 0.028; (b) For 25 cm, the p value was 0.0169; (c) For 28 cm, the p value was 0.01005 and (d) For 30 cm, the p value was 0.01703. Conclusion Our results show that the flexible lateral isocenter contributes significantly to the reduction of the air-kerma rate, and thus to a safer environment in terms of dose lowering both for patients and staff.

  20. Influence of scatter reduction method and monochromatic beams on image quality and dose in mammography.

    PubMed

    Moeckli, Raphaël; Verdun, Francis R; Fiedler, Stefan; Pachoud, Marc; Bulling, Shelley; Schnyder, Pierre; Valley, Jean-François

    2003-12-01

    In mammography, the image contrast and dose delivered to the patient are determined by the x-ray spectrum and the scatter to primary ratio S/P. Thus the quality of the mammographic procedure is highly dependent on the choice of anode and filter material and on the method used to reduce the amount of scattered radiation reaching the detector. Synchrotron radiation is a useful tool to study the effect of beam energy on the optimization of the mammographic process because it delivers a high flux of monochromatic photons. Moreover, because the beam is naturally flat collimated in one direction, a slot can be used instead of a grid for scatter reduction. We have measured the ratio S/P and the transmission factors for grids and slots for monoenergetic synchrotron radiation. In this way the effect of beam energy and scatter rejection method were separated, and their respective importance for image quality and dose analyzed. Our results show that conventional mammographic spectra are not far from optimum and that the use of a slot instead of a grid has an important effect on the optimization of the mammographic process. We propose a simple numerical model to quantify this effect.

  1. Radiation Dose Reduction during Radial Cardiac Catheterization: Evaluation of a Dedicated Radial Angiography Absorption Shielding Drape.

    PubMed

    Ertel, Andrew; Nadelson, Jeffrey; Shroff, Adhir R; Sweis, Ranya; Ferrera, Dean; Vidovich, Mladen I

    2012-01-01

    Objectives. Radiation scatter protection shield drapes have been designed with the goal of decreasing radiation dose to the operators during transfemoral catheterization. We sought to investigate the impact on operator radiation exposure of various shielding drapes specifically designed for the radial approach. Background. Radial access for cardiac catheterization has increased due to improved patient comfort and decreased bleeding complications. There are concerns for increased radiation exposure to patients and operators. Methods. Radiation doses to a simulated operator were measured with a RadCal Dosimeter in the cardiac catheterization laboratory. The mock patient was a 97.5 kg fission product phantom. Three lead-free drape designs were studied. The drapes were placed just proximal to the right wrist and extended medially to phantom's trunk. Simulated diagnostic coronary angiography included 6 minutes of fluoroscopy time and 32 seconds of cineangiography time at 4 standard angulated views (8 s each), both 15 frames/s. ANOVA with Bonferroni correction was used for statistical analysis. Results. All drape designs led to substantial reductions in operator radiation exposure compared to control (P < 0.0001). The greatest decrease in radiation exposure (72%) was with the L-shaped design. Conclusions. Dedicated radial shielding drapes decrease radiation exposure to the operator by up to 72% during simulated cardiac catheterization.

  2. Prioritizing Examination-Centered over Patient-Centered Dose Reduction: A Hazard of Institutional “Benchmarking”

    PubMed Central

    Eisenberg, Jonathan D.; Gilmore, Michael E.; Kalra, Mannudeep K.; Kong, Chung Yin; Pandharipande, Pari V.

    2014-01-01

    Purpose To evaluate whether examination-specific radiation dose metrics reliably measure an institution's success in reducing cancer risks. Materials and Methods We projected health benefits from dose-reduction programs in a hypothetical institution that sought to decrease exposures from abdominopelvic CT. Using modeling techniques to project radiation-induced cancer risks, and tertiary center data to inform the institution's abdominopelvic CT age distribution, we compared: a program in which effective doses were reduced equally (from 10 to 7-mSv) across all scans; to programs in which dose reduction was age-dependent. For each program, we projected lethal cancers averted, life expectancy gained, and average institutional dose achieved. Markov Chain Monte Carlo methods were used to estimate uncertainty in projections. Results The analysis’ age distribution drew from 20,979 CT scans; 39% were from patients ≥65-years-old. To illustrate trends yielded, if all patients in the hypothetical institution received 7-mSv (instead of 10-mSv) scans, we projected the maximum number of lethal cancers averted to be 7/100,000 patients, and maximum life expectancy gained to be 0.26 days per patient, when averaged over the institution's population. When restricting dose reduction (from 10 to 7-mSv) to patients <65-years-old, benefits were slightly lower (5/100,000 patients, 0.22 days gained); however, the average institutional dose was substantially higher (8.2-mSv). While dose reduction in ≥65-year-old patients accounted for only 16% of possible institutional life expectancy gains, this patient group contributed disproportionately (39%) to the institution's average dose. Conclusion Institutional examination-specific dose metrics can be misleading, because the least benefited patients may contribute disproportionately towards “improved” averages. PMID:24758661

  3. 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.

  4. Stimulant Reduction Intervention using Dosed Exercise (STRIDE) - CTN 0037: Study protocol for a randomized controlled trial

    PubMed Central

    2011-01-01

    Background There is a need for novel approaches to the treatment of stimulant abuse and dependence. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse, with direct effects on decreased use and craving. In addition, exercise has the potential to improve other health domains that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight gain, quality of life, and anhedonia, since it has been shown to improve many of these domains in a number of other clinical disorders. Furthermore, neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes. The current manuscript presents the rationale, design considerations, and study design of the National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE) study. Methods/Design STRIDE is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. This study will evaluate individuals diagnosed with stimulant abuse or dependence who are receiving treatment in a residential setting. Three hundred and thirty eligible and interested participants who provide informed consent will be randomized to one of two treatment arms: Vigorous Intensity High Dose Exercise Augmentation (DEI) or Health Education Intervention Augmentation (HEI). Both groups will receive TAU (i.e., usual care). The treatment arms are structured such that the quantity of visits is similar to allow for equivalent contact between groups. In both arms, participants will begin with supervised sessions 3 times per week during the 12-week acute phase of the study. Supervised sessions will be conducted as one-on-one (i.e., individual) sessions, although other

  5. Stimulant reduction intervention using dosed exercise (STRIDE) - CTN 0037: study protocol for a randomized controlled trial.

    PubMed

    Trivedi, Madhukar H; Greer, Tracy L; Grannemann, Bruce D; Church, Timothy S; Somoza, Eugene; Blair, Steven N; Szapocznik, Jose; Stoutenberg, Mark; Rethorst, Chad; Warden, Diane; Ring, Kolette M; Walker, Robrina; Morris, David W; Kosinski, Andrzej S; Kyle, Tiffany; Marcus, Bess; Crowell, Becca; Oden, Neal; Nunes, Edward

    2011-09-19

    There is a need for novel approaches to the treatment of stimulant abuse and dependence. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse, with direct effects on decreased use and craving. In addition, exercise has the potential to improve other health domains that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight gain, quality of life, and anhedonia, since it has been shown to improve many of these domains in a number of other clinical disorders. Furthermore, neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes. The current manuscript presents the rationale, design considerations, and study design of the National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE) study. STRIDE is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. This study will evaluate individuals diagnosed with stimulant abuse or dependence who are receiving treatment in a residential setting. Three hundred and thirty eligible and interested participants who provide informed consent will be randomized to one of two treatment arms: Vigorous Intensity High Dose Exercise Augmentation (DEI) or Health Education Intervention Augmentation (HEI). Both groups will receive TAU (i.e., usual care). The treatment arms are structured such that the quantity of visits is similar to allow for equivalent contact between groups. In both arms, participants will begin with supervised sessions 3 times per week during the 12-week acute phase of the study. Supervised sessions will be conducted as one-on-one (i.e., individual) sessions, although other participants may be exercising

  6. 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.

  7. New noise reduction method for reducing CT scan dose: Combining Wiener filtering and edge detection algorithm

    NASA Astrophysics Data System (ADS)

    Anam, Choirul; Haryanto, Freddy; Widita, Rena; Arif, Idam

    2015-09-01

    New noise reduction method for reducing dose of CT scans has been proposed. The new method is expected to address the major problems in the noise reduction algorithm, i.e. the decreasing in the spatial resolution of the image. The proposed method was developed by combining adaptive Wiener filtering and edge detection algorithms. The first step, the image was filtered with a Wiener filter. Separately, edge detection operation performed on the original image using the Prewitt method. The next step, a new image was generated based on the edge detection operation. At the edge area, the image was taken from the original image, while at the non-edge area, the image was taken from the image that had been filtered with a Wiener filter. The new method was tested on a CT image of the spatial resolution phantom, which was scanned by different current-time multiplication, namely 80, 130 and 200 mAs, while other exposure factors were kept in constant conditions. The spatial resolution phantom consists of six sets of bar pattern made of plexi-glass and separated at some distance by water. The new image quality assessed from the amount of noise and the magnitude of spatial resolution. Noise was calculated by determining the standard deviation of the homogeneous regions, while the spatial resolution was assessed by observation of the area sets of the bar pattern. In addition, to evaluate the performance of this new method has also been tested on patient CT images. From the measurements, the new method can reduce the noise to an average 64.85%, with a spatial resolution does not decrease significantly. Visually, the third set bar on the image phantom (the distance between the bar 1.0 mm) can still be distinguished, as well as on the original image. Meanwhile, if the image is only processed using Wiener filter, the second set bar (the distance between the bar 1.3 mm) are distinguishable. Testing this new method to patient image, its results in relatively the same. Thus, using this

  8. A pilot study investigating two dose reduction techniques for AP lumbar spine radiography using direct dosimetry and Projection VR.

    PubMed

    Shanahan, M C

    2017-08-01

    The purpose of this study was to compare radiation dose measurements generated using a virtual radiography simulation with experimental dosimeter measurements for two radiation dose reduction techniques in digital radiography. Entrance Surface Dose (ESD) measurements were generated for an antero-posterior lumbar spine radiograph experimentally using NanoDOT™, single point dosimeters, for two radiographic systems (systems 1 and 2) and using Projection VR™, a virtual radiography simulation (system 3). Two dose reduction methods were tested, application of the 15% kVp rule, or simplified 10 kVp rule, and the exposure maintenance formula. The 15% or 10 kVp rules use a specified increase in kVp and halving of the mAs to reduce patient ESD. The exposure maintenance formula uses the increase in source-to-object distance to reduce ESD. Increasing kVp from 75 to 96 kVp, with the concomitant decrease in mAs, resulted in percent ESD reduction of 59.5% (4.02-1.63 mGy), 60.8% (3.55-1.39 mGy), and 60.3% (6.65-2.64 mGy), for experimental systems 1 and 2, and virtual simulation (system 3), respectively. Increasing the SID (with the appropriate increase in mAs) from 100 to 140 cm reduced ESD by 22.3% 18.8%, and 23.5%, for experimental systems 1 and 2, and virtual simulation (system 3), respectively. Percent dose reduction measurements were similar between the experimental and virtual measurement systems investigated. For the dose reduction practices tested, Projection VR™ provides a realistic alternate of percent dose reduction to direct dosimetry. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

  9. Projection space denoising with bilateral filtering and CT noise modeling for dose reduction in CT

    SciTech Connect

    Manduca, Armando; Yu Lifeng; Trzasko, Joshua D.; Khaylova, Natalia; Kofler, James M.; McCollough, Cynthia M.; Fletcher, Joel G.

    2009-11-15

    -off than a series of commercial reconstruction kernels. This improvement in noise-resolution properties can be used for improving image quality in CT and can be translated into substantial dose reduction.

  10. Projection space denoising with bilateral filtering and CT noise modeling for dose reduction in CT.

    PubMed

    Manduca, Armando; Yu, Lifeng; Trzasko, Joshua D; Khaylova, Natalia; Kofler, James M; McCollough, Cynthia M; Fletcher, Joel G

    2009-11-01

    reconstruction kernels. This improvement in noise-resolution properties can be used for improving image quality in CT and can be translated into substantial dose reduction.

  11. Radiation Dose Reduction in Paranasal Sinus CT: With Feasibility of Iterative Reconstruction Technique.

    PubMed

    Bang, Minseo; Choi, Seong Hoon; Park, Jongha; Kang, Byeong Seong; Kwon, Woon Jung; Lee, Tae Hoon; Nam, Jung Gwon

    2016-12-01

    To (1) compare the radiation dose of low-dose computed tomography (CT) to that of standard-dose CT, (2) determine the minimum optimal radiation dose for use in patients who need endoscopic sinus surgery, and (3) assess the reliability of iterative model reconstruction. Prospective single-institution study. Tertiary care center. We recruited 48 adults with medically refractory sinusitis. Each patient underwent 4 scans with different CT parameters: 120 kV and 100 mAs (standard dose), 100 kV and 40 mAs (low dose), 100 kV and 20 mAs (very low dose), and 100 kV and 10 mAs (ultra-low dose). All CT scans were reconstructed via filtered back-projection, and ultra-low dose scans were additionally reconstructed through iterative model reconstruction. Radiation dose, image quality, and diagnostic performance were compared among the scans. Radiation doses decreased to 6% (ultra-low dose), 12% (very low dose), and 22% (low dose) of the standard-dose CT. The image quality of low-dose CT was similar to that of standard-dose CT. Ultra-low-dose CT with iterative model reconstruction was inferior to standard-dose CT for identifying anatomic structures, except for the optic nerve. All CT scans had 100% agreement for diagnosing rhinosinusitis. With low-dose CT, the radiation dose can be decreased to 22% of that of standard-dose CT without affecting the image quality. Low-dose CT can be considered the minimum optimal radiation for patients who need surgery. Iterative model reconstruction is not useful for assessing the anatomic details of the paranasal sinus on CT. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

  12. Automatic exposure control in pediatric and adult multidetector CT examinations: A phantom study on dose reduction and image quality

    SciTech Connect

    Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

    2008-10-15

    The aim of this study was to assess the potential of a modern x,y,z modulation-based automatic exposure control system (AEC) for dose reduction in pediatric and adult multidetector CT (MDCT) imaging and evaluate the quality of the images obtained. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-, 5-, 10-year old child, and adult were scanned with a MDCT scanner, equipped with a modern AEC system. Dose reduction (%DR) was calculated as the percentage difference of the mean modulated and the preset tube current-time product that is prescribed for standard head and body scan protocols. The effect of the tube potential and the orientation of the topogram acquisition on dose reduction were assessed. Image quality was evaluated on the basis of image noise and signal to noise ratio (SNR). The dose reduction values achieved in pediatric phantoms were remarkably lower than those achieved for the adult. The efficiency of the AEC is decreased at 80 kVp compared to higher tube potentials and for helical scans following an anterior posterior (AP-AEC) compared to a lateral (LAT-AEC) topogram acquisition. In AP-AEC scans, the dose reduction ranged between 4.7 and 34.7% for neonate, 15.4 and 30.9% for 1 year old, 3.1 and 26.7% for 5 years old, 1.2 and 58.7% for 10 years old, and 15.5 and 57.4% for adult. In LAT-AEC scans, the corresponding dose reduction ranged between 11.0 and 36.5%, 27.2 and 35.7%, 11.3 and 35.6%, 0.3 and 67.0%, and 15.0 and 61.7%, respectively. AP-AEC scans resulted in a 17.1% and 19.7% dose increase in the thorax of neonate and the pelvis of the 10-year old phantom, respectively. The variation in the measured noise among images obtained along the scanning z axis was lower in AEC activated compared to fixed milliamperes scans. However, image noise was significantly increased (P<.001) and SNR significantly decreased (P<.001) in most AEC activated compared to fixed milliamperes scans. In conclusion, AEC resulted in a (i

  13. Moving back: The radiation dose received from lumbar spine quantitative fluoroscopy compared to lumbar spine radiographs with suggestions for dose reduction

    PubMed Central

    Mellor, F.E.; Thomas, P.; Breen, A.

    2014-01-01

    Purpose Quantitative fluoroscopy is an emerging technology for assessing continuous inter-vertebral motion in the lumbar spine, but information on radiation dose is not yet available. The purposes of this study were to compare the radiation dose from quantitative fluoroscopy of the lumbar spine with lumbar spine radiographs, and identify opportunities for dose reduction in quantitative fluoroscopy. Methods Internationally reported dose area product (DAP) and effective dose data for lumbar spine radiographs were compared with the same for quantitative fluoroscopy and with data from a local hospital for functional radiographs (weight bearing AP, lateral, and/or flexion and extension) (n = 27). The effects of procedure time, age, weight, height and body mass index on the fluoroscopy dose were determined by multiple linear regression using SPSS v19 software (IBM Corp., Armonck, NY, USA). Results and conclusion The effective dose (and therefore the estimated risk) for quantitative fluoroscopy is 0.561 mSv which is lower than in most published data for lumbar spine radiography. The dose area product (DAP) for sagittal (flexion + extension) quantitative fluoroscopy is 3.94 Gy cm2 which is lower than local data for two view (flexion and extension) functional radiographs (4.25 Gy cm2), and combined coronal and sagittal dose from quantitative fluoroscopy (6.13 Gy cm2) is lower than for four view functional radiography (7.34 Gy cm2). Conversely DAP for coronal and sagittal quantitative fluoroscopy combined (6.13 Gy cm2) is higher than that published for both lumbar AP or lateral radiographs, with the exception of Nordic countries combined data. Weight, procedure time and age were independently positively associated with total dose, and height (after adjusting for weight) was negatively associated, thus as height increased, the DAP decreased. PMID:26512196

  14. 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.

  15. 28-day intraocular pressure reduction with a single dose of brimonidine tartrate-loaded microspheres.

    PubMed

    Fedorchak, Morgan V; Conner, Ian P; Medina, Carlos A; Wingard, Jeremy B; Schuman, Joel S; Little, Steven R

    2014-08-01

    Treatment of glaucoma by intraocular pressure (IOP) reduction is typically accomplished through the administration of eye drops, the difficult and frequent nature of which contributes to extremely low adherence rates. Poor adherence to topical treatment regimens in glaucoma patients can lead to irreversible vision loss and increased treatment costs. Currently there are no approved treatments for glaucoma that address the inherent inefficiencies in drug delivery and patient adherence. Brimonidine tartrate (BT), a common glaucoma medication, requires dosing every 8-12 h, with up to 97% of patients not taking it as prescribed. This study provides proof-of-principle testing of a controlled release BT formulation. BT was encapsulated in poly(lactic-co-glycolic) acid microspheres and drug release was quantified using UV-Vis spectroscopy. For in vivo studies, rabbits were randomized to receive a single subconjunctival injection of blank (no drug) or BT-loaded microspheres or twice daily topical 0.2% BT drops. The microspheres released an average of 2.1 ± 0.37 μg BT/mg microspheres/day in vitro. In vivo, the percent decrease in IOP from baseline was significantly greater in the treated eye for both topical drug and drug-loaded microspheres versus blank microspheres throughout the 4-week study, with no evidence of migration or foreign body response. IOP measurements in the contralateral, untreated eyes also suggested a highly localized effect from the experimental treatment. A treatment designed using the release systems described in this study would represent a vast improvement over the current clinical standard of 56-84 topical doses over 28 days.

  16. The effect of reduction of propellant mass fraction on the injection profile of metered dose inhalers.

    PubMed

    Ju, Dehao; Shrimpton, John; Hearn, Alex

    2010-05-31

    In order to provide an improved understanding of the flow in pressurized-metered dose inhalers (pMDIs), especially monitoring the output temperature and mass flow rate to obtain maximum atomization efficiency from the available energy, a numerical model for a two phases, multi-component compressible flow in a pressurized-metered dose inhaler is presented and validated. It is suitable for testing with various formulations and different geometries for a range of pMDI devices. We validated the model against available data in the literature for a single component HFA 134a propellant, and then investigated the response of the model to other formulations containing non-volatile components. Further validation is obtained by an experiment using the dual beam method which acquired the actuation flow properties such as spray velocity and duration. The deviation of the numerical predictions for the peak exit velocity against the experimental results is 5.3% and that for effective spray duration 5.0%. From the numerical and experimental results, it is found that for the formulations with the mass fraction of HFA 134a>80%, the effective spray duration of the pMDI is around 0.1s. Furthermore the droplet peak exit velocity at the axial station x=25 mm from the actuation nozzle decreases from 20 to 15m/s with the reduction of the propellant (HFA 134a) from 95%. Formulations with the mass fraction of HFA 134a below 80% produce poor quality spray which is indicated from the unsteady peak exit velocity, changeable spray number density in each experimental test, and numerical simulations also confirmed the non-viability of this condition. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  17. 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

  18. 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.

  19. Diuretics enhance effects of increased dose of candesartan on ambulatory blood pressure reduction in Japanese patients with uncontrolled hypertension treated with medium-dose angiotensin II receptor blockers.

    PubMed

    Sakima, Atsushi; Kita, Toshihiro; Nakada, Seigo; Yokota, Naoto; Tamaki, Noboru; Etoh, Takuma; Shimokubo, Toru; Kitamura, Kazuo; Takishita, Shuichi; Ohya, Yusuke

    2014-01-01

    Abstract Although blockade of the renin-angiotensin system by increasing the dose of angiotensin II receptor blockers (ARBs) is recommended to achieve clinical benefits in terms of blood pressure (BP) control and cardiovascular and renal outcomes, the effect of this increased dose on ambulatory BP monitoring has not been evaluated completely in Japanese patients with uncontrolled hypertension undergoing medium-dose ARB therapy. The primary objective of this study was to examine the effect of the relatively high dose of the ARB candesartan (12 mg/day) on 24-h systolic BP and the attainment of target BP levels in uncontrolled hypertension treated with a medium dose of ARBs. A total of 146 hypertensive patients (age: 69.9 ± 9.3 years; females: 65.8%) completed the study. After switching to candesartan at 12 mg/day, all these BP measurements decreased significantly (p<0.001). Attainment of the target office BP (p=0.0014) and 24-h BP levels (p=0.0296) also improved significantly. Subgroup analysis indicated that the reduction of 24-h systolic BP was larger in patients treated with diuretics than those without (p=0.0206). Multivariate analysis revealed a significant correlation between the combined ARB and diuretic therapy, and the change in 24-h systolic BP irrespective of preceding ARBs. In conclusion, the switching therapy to increased dose of candesartan caused significant reductions in office and ambulatory BP levels, and improved the attainment of target BP levels in patients with uncontrolled hypertension treated with a medium dose of ARBs. Combination with diuretics enhanced this effect.

  20. High Atomic Number Contrast Media Offer Potential for Radiation Dose Reduction in Contrast-Enhanced Computed Tomography.

    PubMed

    Roessler, Ann-Christin; Hupfer, Martin; Kolditz, Daniel; Jost, Gregor; Pietsch, Hubertus; Kalender, Willi A

    2016-04-01

    Spectral optimization of x-ray computed tomography (CT) has led to substantial radiation dose reduction in contrast-enhanced CT studies using standard iodinated contrast media. The purpose of this study was to analyze the potential for further dose reduction using high-atomic-number elements such as hafnium and tungsten. As in previous studies, spectra were determined for which the patient dose necessary to provide a given contrast-to-noise ratio (CNR) is minimized. We used 2 different quasi-anthropomorphic phantoms representing the liver cross-section of a normal adult and an obese adult patient with the lateral widths of 360 and 460 mm and anterior-posterior heights of 200 and 300 mm, respectively. We simulated and measured on 2 different scanners with x-ray spectra from 80 to 140 kV and from 70 to 150 kV, respectively. We determined the contrast for iodine-, hafnium-, and tungsten-based contrast media, the noise, and 3-dimensional dose distributions at all available tube voltages by measurements and by simulations. The dose-weighted CNR was determined as optimization parameter. Simulations and measurements were in good agreement regarding their dependence on energy for all parameters investigated. Hafnium provided the best performance for normal and for obese patient phantoms, indicating a dose reduction potential of 30% for normal and 50% for obese patients at 120 kV compared with iodine; this advantage increased further with higher kV values. Dose-weighted CNR values for tungsten were always slightly below the hafnium results. Iodine proved to be the superior choice at voltage values of 80 kV and below. Hafnium and tungsten both seem to be candidates for contrast-medium-enhanced CT of normal and obese adult patients with strongly reduced radiation dose at unimpaired image quality. Computed tomography examinations of obese patients will decrease in dose for higher kV values.

  1. Study of the radiation dose reduction capability of a CT reconstruction algorithm: LCD performance assessment using mathematical model observers

    NASA Astrophysics Data System (ADS)

    Fan, Jiahua; Tseng, Hsin-Wu; Kupinski, Matthew; Cao, Guangzhi; Sainath, Paavana; Hsieh, Jiang

    2013-03-01

    Radiation dose on patient has become a major concern today for Computed Tomography (CT) imaging in clinical practice. Various hardware and algorithm solutions have been designed to reduce dose. Among them, iterative reconstruction (IR) has been widely expected to be an effective dose reduction approach for CT. However, there is no clear understanding on the exact amount of dose saving an IR approach can offer for various clinical applications. We know that quantitative image quality assessment should be task-based. This work applied mathematical model observers to study detectability performance of CT scan data reconstructed using an advanced IR approach as well as the conventional filtered back-projection (FBP) approach. The purpose of this work is to establish a practical and robust approach for CT IR detectability image quality evaluation and to assess the dose saving capability of the IR method under study. Low contrast (LC) objects imbedded in head size and body size phantoms were imaged multiple times with different dose levels. Independent signal present and absent pairs were generated for model observer study training and testing. Receiver Operating Characteristic (ROC) curves for location known exact and location ROC (LROC) curves for location unknown as well as their corresponding the area under the curve (AUC) values were calculated. Results showed approximately 3 times dose reduction has been achieved using the IR method under study.

  2. 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

  3. 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.

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

    PubMed Central

    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

    2016-01-01

    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

  5. 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

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

    PubMed

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

    2015-11-01

    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. 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. 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. Although a novel image-based denoising technique performed better than a commercial iterative reconstruction method in pediatric abdominopelvic CT examinations, it performed worse in

  7. 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

  8. A method for patient dose reduction in dynamic contrast enhanced CT study

    SciTech Connect

    Mo Kim, Sun; Haider, Masoom A.; Milosevic, Michael; Jaffray, David A.; Yeung, Ivan W. T.

    2011-09-15

    Purpose: In dynamic contrast enhanced CT (DCE-CT) study, prolonged CT scanning with high temporal resolution is required to give accurate and precise estimates of kinetic parameters. However, such scanning protocol could lead to substantial radiation dose to the patient. A novel method is proposed to reduce radiation dose to patient, while maintaining high accuracy for kinetic parameter estimates in DCE-CT study. Methods: The method is based on a previous investigation that the arterial impulse response (AIR) in DCE-CT study can be predicted using a population-based scheme. In the proposed method, DCE-CT scanning is performed with relatively low temporal resolution, hence, giving rise to reduction in patient dose. A novel method is proposed to estimate the arterial input function (AIF) based on the coarsely sampled AIF. By using the estimated AIF in the tracer kinetic analysis of the coarsely sampled DCE-CT study, the calculated kinetic parameters are able to achieve a high degree of accuracy. The method was tested on a DCE-CT data set of 48 patients with cervical cancer scanned at high temporal resolution. A random cohort of 34 patients was chosen to construct the orthonormal bases of the AIRs via singular value decomposition method. The determined set of orthonormal bases was used to fit the AIFs in the second cohort (14 patients) at varying levels of down sampling. For each dataset in the second cohort, the estimated AIF was used for kinetic analyses of the modified Tofts and adiabatic tissue homogeneity models for each of the down-sampling schemes between intervals from 2 to 15 s. The results were compared with analyses done with the ''raw'' down-sampled AIF. Results: In the first group of 34 patients, there were 11 orthonormal bases identified to describe the AIRs. The AIFs in the second group were estimated in high accuracy based on the 11 orthonormal bases established in the first group along with down-sampled AIFs. Using the 11 orthonormal bases, the

  9. Significant Radiation Dose Reduction in the Hybrid Operating Room Using a Novel X-ray Imaging Technology.

    PubMed

    van den Haak, R F F; Hamans, B C; Zuurmond, K; Verhoeven, B A N; Koning, O H J

    2015-10-01

    To prospectively quantify radiation dose change in aortoiliac endovascular procedures in the hybrid operating room (OR) for patients and medical staff with a novel X-ray imaging technology (ClarityIQ technology), and to assess whether procedure or fluoroscopy time or dose of iodinated contrast was affected. A prospective study including 138 patients was performed to compare radiation dose before and after installation of a novel X-ray imaging technology. Endovascular aneurysm repair (EVAR) was performed in 37 patients and an endovascular procedure for aortoiliac occlusive disease (AIOD) in 101. Patient radiation dose in air kerma (AK) and dose area product (DAP), patient demographics, and procedural data were recorded. Staff radiation dose was measured with real time personal dosimetry measurements. In both the EVAR and AIOD groups the reference system, ALX (AlluraXper FD20; Philips Healthcare, Best, the Netherlands), was compared with the upgraded X-ray system, CIQ (AlluraClarity FD20; Philips Healthcare). Procedure time, fluoroscopy time, and iodinated contrast dose were recorded. Patient radiation dose reduction in the EVAR group, in median AK, was 56% (ALX = 1,262.5 mGy; CIQ = 556.0 mGy [p < .01]); and in median DAP it was 57% (ALX = 224.4 Gycm(2) and CIQ = 95.8 Gycm(2) [p < .01]). Patient radiation dose reduction in the AIOD group, in median AK, was 76% (ALX = 1,011.0 mGy; CIQ = 248.0 mGy [p < .01]); and in median DAP it was 73% (ALX = 138.1 Gycm(2); CIQ = 38.0 Gycm(2) [p < .01]). Staff dose reduction in the EVAR group was 16% (ALX = 70.1 μSv; CIQ = 59.2 μSv [p = .43]) and in the AIOD group it was 69% (ALX = 96.2 μSv; CIQ = 30.1 μSv [p < .01]). There was no statistically significant difference between patient demographics, procedure time, fluoroscopy time, and iodinated contrast medium use in the two treatment groups before and after installation. A novel X-ray imaging technology in the hybrid OR suite resulted in a significant reduction of patient and

  10. Radiation dose reduction in scoliosis patients: low-dose full-spine radiography with digital flat panel detector and image stitching system.

    PubMed

    Grieser, T; Baldauf, A Q; Ludwig, K

    2011-07-01

    To evaluate the exposure dose reduction with a digital flat panel detector (FPD) and an image stitching system (ISS) in full-spine radiography for scoliosis patients. During a 6-month period, all consecutive scoliosis patients with a clinical indication for full-spine radiography (n = 50) were examined with an FPD and ISS. Automatic exposure control adjusted to speed class 1600 was used together with age-adjusted tube voltage and filtration. Dose area products were recorded for all images (antero-posterior n = 50, lateral n = 18). Images were evaluated by two radiologists for the possibility (possible, impossible) of typical scoliosis measurements (Cobb angle, Stagnara angle, lateral deviation, Risser stage). All measurements assessed as impossible underwent a second evaluation categorizing the reason why a measurement was impossible (underlying pathology, projection, image quality). Patient characteristics influencing exposure were recorded (sex, age, weight, height). Mean dose area products were compared to the literature with consideration of patient group and image quality. The mean dose area product was 16.8 µGy m (2) for antero-posterior images and 26.6 µGy m (2) for lateral images. A comparison to published values showed an exposure dose reduction of 47 % to 93 %. Measurement of the Cobb and Stagnara angle, lateral deviation and Risser stage was possible in 96 % (n = 50), 83 % (n = 18), 100 % (n = 50) and 100 % (n = 50) of cases. The reasons for impossible measurements were independent of image quality (underlying pathologies, projection). When imaging scoliosis patients, an FPD combined with an ISS can substantially reduce the exposure dose. © Georg Thieme Verlag KG Stuttgart · New York.

  11. 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

  12. 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.

  13. Dose reduction efforts for pediatric head CT imaging in Washington State trauma centers: follow-up survey results.

    PubMed

    Graves, Janessa M; Kanal, Kalpana M; Rivara, Frederick P; Jarvik, Jeffrey G; Vavilala, Monica S

    2014-02-01

    To examine variation in pediatric trauma head CT imaging protocols in Washington State trauma centers (TCs) in 2012 and compare to a previous survey conducted in 2008-2009. A mixed-mode (online and paper) survey was sent to all adult and pediatric Washington State TCs (levels 1-5). Respondents provided information about the CT scanner used for pediatric head scans and technical information about pediatric dose reduction protocols. Mean head effective dose and organ dose for a female baby were estimated. Results were compared with previous data. Sixty-one of 76 TCs responded to the 2012 survey (response rate, 80.3%, versus 76% for 2008-2009 survey). In 2012, 91.7% reported having a dedicated pediatric protocol (87.7% in 2008-2009). Protective shielding use ranged from 80% to 100% across both survey years. In 2012, 2.5 times more TCs provided sufficient information to conduct dose calculations than in 2008-2009. Estimated mean CT dose index was 23.1 milliGray (mGy) in 2012, compared with 34.8 mGy in 2008-2009 (P = .01). Estimated mean dose length product was also significantly lower in 2012 than 2008-2009 (307.6 mGy × cm versus 430.1 mGy × cm, respectively; P = .04). Wide variation in mean effective dose was observed for level 3 and 4 TCs in 2012, similar to variation observed in 2008-2009 among level 4 TCs. Mean organ dose was significantly lower in 2012 for eye lens and brain, but higher for thyroid than in 2008-2009 (P < .05). Although most Washington State TCs employ dose reduction protocols for pediatric head CTs, and some measures were lower in 2012, variation in protocols use and estimated dose continues to exist. More complete responses in 2012 suggest improved understanding of the importance of pediatric dose reduction efforts. Education and institutional protocols are necessary to reduce pediatric radiation dose from head CTs. Copyright © 2014 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  14. Skin and gonadal dose reduction during hip radiography of the bull.

    PubMed

    Wood, A K; Blockey, B; Reynolds, K M; Leith, I S; Burns, P A

    1979-10-01

    Radiology is being used to an increasing extent in the clinical diagnosis of hip lameness in bulls. Consequent gonadal doses may have important implications in later breeding programmes. Skin and gonadal doses were recorded during hip radiography of 18 bulls. An additional 0.13 mm copper filtration reduced skin dose by more than one third, but had no effect on gonadal dose. The average radiation dose to the gonads was approximately halved by completely surrounding the scrotum with lead sheeting 0.95 mm in thickness.

  15. Exposure reductions encouraged by the determination of the effective dose equivalent for non-uniform exposures

    SciTech Connect

    Matheny, M.D.; Brown, C.G.; Dyer, S.G.

    1994-08-01

    DOE Order 5480.11 requires calculation of the effective dose equivalent (EDE) due to non-uniform radiation fields using ICRP-26 weighting factors. To comply with this requirement, Westinghouse Savannah River Company (WSRC) developed a simple dose calculation scheme based on a draft report by the External Dosimetry Working Group of the Health Physics Society Standards Committee. The calculations involved are fairly simple and provide a conservative dose estimate. The resulting EDE estimate provides a much better representation of the risk to the monitored individual than the more prevalent practice of assigning the highest measured dose. Details of the dose assessment methodology are included as an attachment.

  16. Adaptive iterative dose reduction (AIDR) 3D in low dose CT abdomen-pelvis: Effects on image quality and radiation exposure

    NASA Astrophysics Data System (ADS)

    Ang, W. C.; Hashim, S.; Karim, M. K. A.; Bahruddin, N. A.; Salehhon, N.; Musa, Y.

    2017-05-01

    The widespread use of computed tomography (CT) has increased the medical radiation exposure and cancer risk. We aimed to evaluate the impact of AIDR 3D in CT abdomen-pelvic examinations based on image quality and radiation dose in low dose (LD) setting compared to standard dose (STD) with filtered back projection (FBP) reconstruction. We retrospectively reviewed the images of 40 patients who underwent CT abdomen-pelvic using a 80 slice CT scanner. Group 1 patients (n=20, mean age 41 ± 17 years) were performed at LD with AIDR 3D reconstruction and Group 2 patients (n=20, mean age 52 ± 21 years) were scanned with STD using FBP reconstruction. Objective image noise was assessed by region of interest (ROI) measurements in the liver and aorta as standard deviation (SD) of the attenuation value (Hounsfield Unit, HU) while subjective image quality was evaluated by two radiologists. Statistical analysis was used to compare the scan length, CT dose index volume (CTDIvol) and image quality of both patient groups. Although both groups have similar mean scan length, the CTDIvol significantly decreased by 38% in LD CT compared to STD CT (p<0.05). Objective and subjective image quality were statistically improved with AIDR 3D (p<0.05). In conclusion, AIDR 3D enables significant dose reduction of 38% with superior image quality in LD CT abdomen-pelvis.

  17. Whole brain radiation dose reduction for primary central nervous system lymphoma patients who achieved partial response after high-dose methotrexate based chemotherapy.

    PubMed

    Park, Jun Su; Lim, Do Hoon; Ahn, Yong Chan; Park, Won; Kim, Seok Jin; Kim, Won Seog; Kim, Kihyun

    2017-08-30

    The whole brain radiotherapy (WBRT) dose for primary central nervous system lymphoma (PCNSL) patients who achieved complete response after induction chemotherapy was recently reduced to 23.4 Gy, but the optimal radiation dose for patients who achieved partial response (PR) is controversial. The aim of this study was to investigate the feasibility of reduced-dose WBRT for patients who achieved PR. We retrospectively reviewed the medical records of PCNSL patients who were treated with high-dose methotrexate based chemotherapy. We compared treatment outcomes between the patients who received WBRT at either 36 Gy or 45 Gy. The overall survival (OS) and intracranial progression-free survival (IC-PFS) was 66.3% and 42.6% at 5 years, respectively. There was no significant difference in treatment outcomes between the patients who received 36 Gy and 45 Gy, especially among patients who achieved PR. Three-year OS was 100% and 83.3% for 36 Gy and 45 Gy group, respectively (P = 0.313). Three-year IC-PFS was 60.0% and 66.7% for 36 Gy and 45 Gy group, respectively (P = 0.916). Findings of our study might provide a possibility for dose-reduction in patients achieving PR to induction chemotherapy, which may in turn reduce delayed neurologic sequelae. However, the number of patients included in this study was too small to lead to a concrete conclusion, thus further study is needed.

  18. The effect of radiation dose reduction on computer-aided detection (CAD) performance in a low-dose lung cancer screening population.

    PubMed

    Young, Stefano; Lo, Pechin; Kim, Grace; Brown, Matthew; Hoffman, John; Hsu, William; Wahi-Anwar, Wasil; Flores, Carlos; Lee, Grace; Noo, Frederic; Goldin, Jonathan; McNitt-Gray, Michael

    2017-04-01

    Lung cancer screening with low-dose CT has recently been approved for reimbursement, heralding the arrival of such screening services worldwide. Computer-aided detection (CAD) tools offer the potential to assist radiologists in detecting nodules in these screening exams. In lung screening, as in all CT exams, there is interest in further reducing radiation dose. However, the effects of continued dose reduction on CAD performance are not fully understood. In this work, we investigated the effect of reducing radiation dose on CAD lung nodule detection performance in a screening population. The raw projection data files were collected from 481 patients who underwent low-dose screening CT exams at our institution as part of the National Lung Screening Trial (NLST). All scans were performed on a multidetector scanner (Sensation 64, Siemens Healthcare, Forchheim Germany) according to the NLST protocol, which called for a fixed tube current scan of 25 effective mAs for standard-sized patients and 40 effective mAs for larger patients. The raw projection data were input to a reduced-dose simulation software to create simulated reduced-dose scans corresponding to 50% and 25% of the original protocols. All raw data files were reconstructed at the scanner with 1 mm slice thickness and B50 kernel. The lungs were segmented semi-automatically, and all images and segmentations were input to an in-house CAD algorithm trained on higher dose scans (75-300 mAs). CAD findings were compared to a reference standard generated by an experienced reader. Nodule- and patient-level sensitivities were calculated along with false positives per scan, all of which were evaluated in terms of the relative change with respect to dose. Nodules were subdivided based on size and solidity into categories analogous to the LungRADS assessment categories, and sub-analyses were performed. From the 481 patients in this study, 82 had at least one nodule (prevalence of 17%) and 399 did not (83%). A total of 118

  19. The effect of dose reduction and feasibility of edge-preserving noise reduction on the detection of liver lesions using MSCT.

    PubMed

    Wessling, Johannes; Esseling, Rainer; Raupach, Rainer; Fockenberg, Stefanie; Osada, Nani; Gerss, Joachim; Heindel, Walter; Fischbach, Roman

    2007-07-01

    The purpose of this study was to assess the effect of dose reduction and the potential of noise reduction filters on image quality and the detection of liver lesions using MSCT. Twenty-nine patients with a total of 40 liver lesions underwent 16-slice CT (120 kV; 180 mAs). Virtual noise was added to CT raw datasets simulating effective mAs levels of 155, 130, 105, 80, 55, 30 and 10 mAs. All datasets were post-processed with an edge-preserving noise-reduction filter (ANR-3D), yielding a total of 15 datasets per patient. Ten radiologists performed independent evaluations of image quality, the presence of liver lesions and diagnostic confidence. Quantitative noise and contrast-to-noise ratios (CNR) were obtained. Superior image quality (P < 0.02), reduction of image noise (P < 0.001) and the increase of lesion-to-liver CNR (P < 0.001) were observed in images processed with the ANR-3D filter. Sensitivity for lesion detection remained unchanged down to 105 mAs (CTDI(w) 6.6 mGy) without filter and 80 mAs (CTDI(w) 5.1 mGy) with ANR-3D. Confidence was rated significantly higher for datasets reconstructed with ANR-3D. The use of a noise-reducing, but edge-preserving filter (ANR-3D) is a promising option to reduce further the radiation dose in liver CT.

  20. MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction.

    PubMed

    Tobalem, Frank; Dugert, Eric; Verdun, Francis R; Dunet, Vincent; Ott, Julien G; Rudiger, Hannes A; Cherix, Stephane; Meuli, Reto; Becce, Fabio

    2014-12-01

    The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose. Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions. With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage. The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.

  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. Yearly reduction of glucocorticoid dose by 50% as tapering schedule achieves complete remission for 124 pemphigus vulgaris patients.

    PubMed

    Wang, Mingyue; Gao, Yu; Peng, Yang; Zhao, Junyu; Chen, Xixue; Zhu, Xuejun

    2016-03-01

    Glucocorticoids are the first-line treatment for pemphigus vulgaris. Among 140 patients receiving systemic glucocorticoids, 124 patients achieved complete remission off or on a prednisone dose of ≤10 mg/day or less for 6 months or more. The mean average steroid controlling doses were 0.65, 0.62, 0.80, 1.08 and 1.38 mg/kg per day for the mucosal-dominant patients and the mild, moderate, severe and extensive cutaneous-involved patients, respectively (P < 0.001). The mean durations of the initial tapering after controlling doses started were 77.98, 48.78, 31.74 and 28.83 days when the disease was controlled with doses of 40 mg/day or less, 45-60 mg/day, 65-80 mg/day and more than 80 mg/day for the cutaneous-involved types, respectively (P < 0.005). Of the patients, 79.51% achieved complete remission within 3 years, 98.36% within 5 years and all within 6 years, which corresponded to a 50% yearly reduction of glucocorticoid dose. These successfully treated patients indicate that a severity-tailored initial dose of glucocorticoids, an initial tapering duration based on the initial dose and a subsequent 50% yearly tapering regimen may cure pemphigus vulgaris within 3-6 years.

  3. Significant dose reduction for pediatric digital subtraction angiography without impairing image quality: preclinical study in a piglet model.

    PubMed

    Racadio, John; Strauss, Keith; Abruzzo, Todd; Patel, Manish; Kukreja, Kamlesh; Johnson, Neil; den Hartog, Mark; Hoornaert, Bart; Nachabe, Rami

    2014-10-01

    The purpose of this study was to validate the hypothesis that image quality of digital subtraction angiography (DSA) in pediatrics is not impaired when using a low-dose acquisition protocol. Three piglets corresponding to common pediatric population sizes were used. DSA was performed in the aorta and renal, hepatic, and superior mesenteric arteries using both the commonly used reference standard and novel radiographic imaging noise reduction technologies to ensure pairwise radiation dose and image quality comparison. The air kerma per frame at the interventional reference point for each DSA acquisition was collected as a radiation dose measure, and image quality was evaluated by five interventional radiologists in a randomized blinded fashion using a 5-point scale. The mean air kerma (± SD) at the interventional reference point with the novel x-ray imaging noise reduction technology was significantly lower (1.1 ± 0.8 mGy/frame) than with the reference technology (4.2 ± 3.0 mGy/frame, p = 0.005). However, image quality was statistically similar, with average scores of 3.2 ± 0.4 and 3.1 ± 0.5 for the novel and reference technologies, respectively (p = 0.934); interrater absolute agreement was 0.77. The DSA radiation dose for pediatrics can be reduced by a factor of four with a novel x-ray imaging noise reduction technology without deterioration of image quality.

  4. Dose reduction efforts for pediatric head CT imaging in Washington State trauma centers: follow-up survey results

    PubMed Central

    Kanal, Kalpana M.; Rivara, Frederick P.; Jarvik, Jeffrey G.; Vavilala, Monica S.

    2014-01-01

    Purpose To examine variation in pediatric trauma head CT imaging protocols in Washington State trauma centers (TCs) in 2012 and compare to a previous survey conducted in 2008/09. Methods A mixed-mode (online and paper) survey was sent to all adult and pediatric Washington State TCs (levels 1–5). Respondents provided information about the CT scanner used for pediatric head scans and technical information about pediatric dose reduction protocols. Mean head effective dose and organ dose for a female baby were estimated. Results were compared to previous data. Results Sixty-one of 76 TCs responded to the 2012 survey (response rate 80.3%; response rate in 2008/09 survey was 76%). In 2012, 91.7% reported having a dedicated pediatric protocol (87.7% in 2008/09). Protective shielding use ranged from 80 to 100% across both survey years. In 2012, 2.5 times more TCs provided sufficient information to conduct dose calculations than in 2008/09. Estimated mean CTDIvol was 23.1 mGy in 2012, compared to 34.8 mGy in 2008/09 (p=0.01). Estimated mean DLP was also significantly lower in 2012 than 2009/08 (307.6 mGy*cm vs. 430.1 mGy*cm, respectively; p=0.04). Wide variation in mean effective dose was observed for level 3 and 4 TCs in 2012, similar to variation observed in 2008/09 among level 4 TCs. Mean organ dose was significantly lower in 2012 for eye lens and brain, but higher for thyroid than 2008/09 (p<0.05). Conclusions While most Washington State TCs employ dose reduction protocols for pediatric head CTs, and some measures were lower in 2012, variation in protocols use and estimated dose continues to exist. More complete responses in 2012 suggest improved understanding of the importance of pediatric dose reduction efforts. Education and institutional protocols are necessary to reduce pediatric radiation dose from head CTs. PMID:24360905

  5. Full dose reduction potential of statistical iterative reconstruction for head CT protocols in a predominantly pediatric population

    PubMed Central

    Mirro, Amy E.; Brady, Samuel L.; Kaufman, Robert. A.

    2016-01-01

    Purpose To implement the maximum level of statistical iterative reconstruction that can be used to establish dose-reduced head CT protocols in a primarily pediatric population. Methods Select head examinations (brain, orbits, sinus, maxilla and temporal bones) were investigated. Dose-reduced head protocols using an adaptive statistical iterative reconstruction (ASiR) were compared for image quality with the original filtered back projection (FBP) reconstructed protocols in phantom using the following metrics: image noise frequency (change in perceived appearance of noise texture), image noise magnitude, contrast-to-noise ratio (CNR), and spatial resolution. Dose reduction estimates were based on computed tomography dose index (CTDIvol) values. Patient CTDIvol and image noise magnitude were assessed in 737 pre and post dose reduced examinations. Results Image noise texture was acceptable up to 60% ASiR for Soft reconstruction kernel (at both 100 and 120 kVp), and up to 40% ASiR for Standard reconstruction kernel. Implementation of 40% and 60% ASiR led to an average reduction in CTDIvol of 43% for brain, 41% for orbits, 30% maxilla, 43% for sinus, and 42% for temporal bone protocols for patients between 1 month and 26 years, while maintaining an average noise magnitude difference of 0.1% (range: −3% to 5%), improving CNR of low contrast soft tissue targets, and improving spatial resolution of high contrast bony anatomy, as compared to FBP. Conclusion The methodology in this study demonstrates a methodology for maximizing patient dose reduction and maintaining image quality using statistical iterative reconstruction for a primarily pediatric population undergoing head CT examination. PMID:27056425

  6. Strategies and Scientific Basis of Dose Reduction on State-of-the-Art Multirow Detector X-Ray CT Systems.

    PubMed

    Karamat, Muhammad Irfan

    2015-01-01

    The continued development in multirow detector computed tomography (MDCT) technology accompanied by tremendous enhancement in the clinical utility and rapid increase in the number of MDCT scanners worldwide are causing a steep rise in the number of diagnostic computed tomography (CT) procedures performed each year. The everincreasing use of this X-radiation-based imaging technique has raised radiation protection concerns among the clinical community and general public. To address these concerns, significant efforts have been made by the clinical community as well as industry, research, and government organizations. Because of these efforts, modern MDCT systems are now equipped with a variety of tools that can lead to "radiation dose-optimized" CT images if used properly. This review describes CT dose metrics and their limitations, radiation dose reduction techniques and strategies implemented using modern MDCT scanners, and the role of research and regulatory organizations in developing guidelines and regulations to facilitate the adoption of the dose reduction strategies. An account of further developments required to achieve submillisievert X-ray CT doses and to make X-ray CT a radiation risk-free imaging modality is also given. A detailed description of the scientific basis and controversies surrounding the linear no threshold (LNT) model, which forms the basis of all radiation dose reduction strategies, is also provided in this review. According to the LNT model, there is no amount of radiation that is safe or beneficial for human beings. Based on recent epidemiological studies, despite all of the controversies, the LNT model continues to be the basis of the ALARA (as low as reasonably achievable) principle of radiation protection framework in CT.

  7. REDUCTION OF BIOLOGICAL EFFECTIVENESS OF X-RAYS AT VERY HIGH DOSE RATES,

    DTIC Science & Technology

    It has been observed that relative biological effectiveness (RBE) of X-rays or gamma rays is independent of dose rate provided that their delivery ... time is short compared to the recuperation time of the organism. At higher dose rates, however, several effects may modify the RBE. One possible

  8. A dose of nature: Tree cover, stress reduction, and gender differences

    Treesearch

    Bin Jiang; Chun-Yen Chang; William C. Sullivan

    2014-01-01

    Although it is well established that exposure to nearby nature can help reduce stress in individuals, the shape of the dose-response curve is entirely unclear. To establish this dose-response curve, we recruited 160 individuals for a laboratory experiment. Participants engaged in the Trier Social Stress Test (TSST) to induce psychological stress, and were then randomly...

  9. [Reduction of radiation dose to the worker in preparing the radiopharmaceutical solution by a simple shielding equipment].

    PubMed

    Miyazaki, Y; Inoue, H; Shiozaki, J; Higuchi, Y; Fujioka, M; Kawaguchi, K; Miyanaga, M; Aburano, T

    1987-01-01

    In order to reduce radiation dose to the hands of examiners who prepare and aspirate radiopharmaceuticals, we made a prototype of simplified manually-operated dispense system, which the syringe and the vial shield with lead were set in the small box made of lead and lead glass. The result showed that our dispense system allowed substantial reduction of radiation dose to the hands and rapid preparation of radiopharmaceuticals compared with the conventional lead shield syringe system, and allowed closer operation, smaller dead volume and lower cost compared with the conventional automatic system.

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

    PubMed

    Lauzier, Pascal Theriault; Chen, Guang-Hong

    2013-02-01

    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. 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. 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; images also had a

  11. 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

  12. Reduction of operator radiation dose by a pelvic lead shield during cardiac catheterization by radial access: comparison with femoral access.

    PubMed

    Lange, Helmut W; von Boetticher, Heiner

    2012-04-01

    This study sought to determine the efficacy of patient pelvic lead shielding for the reduction of operator radiation exposure during cardiac catheterization via the radial access in comparison with the femoral access. Cardiac catheterization via the radial access is associated with significantly increased radiation dose to the patient and the operator. Improvements in radiation protection are needed to minimize this drawback. Pelvic lead shielding has the potential to reduce operator radiation dose. We randomly assigned 210 patients undergoing elective coronary angiography by the same operator to a radial and femoral access with and without pelvic lead shielding of the patient. Operator radiation dose was measured by a radiation dosimeter attached to the outside breast pocket of the lead apron. For radial access, operator dose decreased from 20.9 ± 13.8 μSv to 9.0 ± 5.4 μSv, p < 0.0001 with pelvic lead shielding. For femoral access, it decreased from 15.3 ± 10.4 μSv to 2.9 ± 2.7 μSv, p < 0.0001. Pelvic lead shielding significantly decreased the dose-area product-normalized operator dose (operator dose divided by the dose-area product) by the same amount for radial and femoral access (0.94 ± 0.28 to 0.39 ± 0.19 μSv × Gy(-1) × cm(-2) and 0.70 ± 0.26 to 0.16 ± 0.13 μSv × Gy(-1) × cm(-2), respectively). Pelvic lead shielding is highly effective in reducing operator radiation exposure for radial as well as femoral procedures. However, despite its use, radial access remains associated with a higher operator radiation dose. Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  13. [Dose reduction and image quality in MDCT of the upper abdomen: potential of an adaptive post-processing filter].

    PubMed

    Kröpil, P; Lanzman, R S; Walther, C; Röhlen, S; Godehardt, E; Mödder, U; Cohnen, M

    2010-03-01

    To evaluate the effects of a 2D non-linear adaptive post-processing filter (2D-NLAF) on image quality in dose-reduced multi-detector CT (MDCT) of the upper abdomen. MDCT of the upper abdomen was simulated on a 64-slice scanner using a multi-modal anthropomorphic phantom (CIRS, Norfolk, USA). While keeping the collimation (64 x 0.6 mm) and pitch (p = 1) unchanged, the tube current (100 - 500 mAs) and tube potential (80 - 140 kVp) were varied to perform MDCT as high dose (CTDI > 20), middle dose (CTDI 10 - 20) and low dose (CTDI < 10) level protocols. Four independent blinded radiologists evaluated axial images with a thickness of 7 and 3 mm with respect to the presentation of "mesenteric low contrast lesions", "liver veins", "liver cysts", "renal cysts" and "big vessels". The subjective image quality of original data and post-processed images using a 2D-NLAF (SharpViewCT, Linköping, Sweden) was graded on a 5-point scale (from "1" not visible to "5" excellent) and statistically analyzed. The effective dose (E) was estimated using commercial software (CT-EXPO). For all protocol groups, 2D-NLAF led to a significant improvement in subjective image quality for all examined lesions (p < 0.01), particularly at the protocols of middle dose (E: 5 - 8 mSv) and low dose level (E: 1 - 5 mSv). A maximum effect was seen in middle dose protocols for "low contrast lesions" (score "3.3" with filter versus "2.5" without) and "liver veins" ("4.5" versus "3.9"). The phantom study indicates a potential dose reduction of up to 50 % in MDCT of the upper abdomen by use of a 2D-NLAF, which should be further examined in clinical trails. Georg Thieme Verlag KG Stuttgart New York.

  14. Larger Blood Pressure Reduction by Fixed-Dose Compared to Free Dose Combination Therapy of ACE Inhibitor and Calcium Antagonist in Hypertensive Patients.

    PubMed

    Visco, Valeria; Finelli, Rosa; Pascale, Antonietta Valeria; Giannotti, Rocco; Fabbricatore, Davide; Ragosa, Nicola; Ciccarelli, Michele; Iaccarino, Guido

    2017-01-01

    The introduction of fixed combination of ACEi+CCB (Fixed) has significantly increased patients compliance and adherence to therapy. At the moment, however, there are no data suggesting the better control of once-daily fixed (Fixed) over free doses in separate administrations combination therapy in hypertensives. In a population of 39 consecutive outpatient patients referred to the departmental Hypertension clinic of the University Hospital of Salerno Medical School with the first diagnosis of arterial hypertension, we tested the hypothesis that the Fixed achieve a better control of blood pressure than the Free combination. Patients were randomized to either strategy and after 3 months patients underwent a clinical assessment to evaluate the antihypertensive effect. The two groups, matched for anthropometric and clinical parameters, received Amlodipine (5-10 mg/daily) and Perindopril (5-10 mg/daily). Perindopril and Amlodipine doses did not significantly differ between the two groups. After 3 months BP control was improved in both groups and BP targets were similarly reached in both groups (SBP; Fixed: 61.54%; Free 69.23%; n.s. DPB; Fixed: 80.77%; Free 84.62%; n.s.). The reduction in systolic blood pressure was similar in both groups (Fixed:7.64±2.49%; Free: 7.81±4.00%, n.s.), while the reduction of diastolic blood pressure was greater in the Fixed group (Fixed: 14.22±2.03%; Free: 4.92±5.00%, p<0.05). Although both strategies are effective in reducing BP, the use of Fixed dose has an advantage in the reduction of BP. The present study does not allow to identify the mechanisms of this difference, which can be assumed to be due to the pharmacokinetics of the drugs administered in once-daily fixed combination.

  15. Facial edema induced by isotretinoin use: a case and a review of the side effects of isotretinoin.

    PubMed

    Scheinfeld, Noah; Bangalore, Sripal

    2006-05-01

    Isotretinoin (13-cis-retinoic acid) is a retinoid that is used to treat cystic acne, comedonal acne, and other diseases. For the treatment of acne, isotretinoin is dosed at 0.5 to 2 mg/kg daily for 5 months with a target total dose of approximately 120 mg/kg. Its most common side effects are mucocutaneous and ocular in nature (ie, cheilitis, ocular sicca, and decreased dark adaptation). It can also cause xerosis. Patients should be made aware of these side effects before taking isotretinoin and also that utilization of moisturizers and eye drops can help to mitigate such side effects. Sometimes, however, the dose of isotretinoin needs to be decreased to reduce the induction of side effects. Isotretinoin's most significant side effect is the induction of birth defects if a fetus is exposed to isotretinoin, which is pregnancy category X. Isotretinoin should be used with 2 forms of birth control by fecund women. It can rarely increase serum levels of triglycerides, which can, if very elevated, be related to the development of pancreatitis and xanthomas. Isotretinoin's well-documented but rarer side effects include intracranial hypertension. It can induce bony changes. A review of the literature demonstrates that isotretinoin is not linked to depression and suicide. Facial swelling has been linked to isotretinoin use in 3 previous case reports. We note herein the first case of facial swelling that occurred in an acne patient being treated with isotretinoin who at the time the swelling developed had no cysts, comedones, pustules, or evidence of bacterial infection. Possible reasons for the patient's facial swelling include some type of retinoid induced angioedema, exacerbation of inflammation by isotretinoin, and isotretinoin induced capillary leak syndrome.

  16. Investigation into the effects of lead shielding for fetal dose reduction in CT pulmonary angiography.

    PubMed

    Kennedy, E V; Iball, G R; Brettle, D S

    2007-08-01

    This work aims to determine whether lead shielding can be used to decrease the radiation dose to the fetus during CT scans for the diagnosis of pulmonary embolism during early stage pregnancy. An anthropomorphic phantom was modified to contain a 15 cc ionization chamber at the site of the uterus to enable fetal dose to be measured. The effects of a range of scan parameters, positioning of lead and thicknesses of lead were investigated. Fetal dose was lower with lower values of kV(p) and mAs. An increasing thickness of lead decreased the radiation dose to the uterus, as did increasing the proportion of the patient covered by the lead shielding. Fetal dose increased exponentially as the edge of the scan volume moved closer to the point of measurement. In no experiment was the dose to the fetus increased by the presence of the lead. It was found that the fetal radiation dose from a CT scan following a pulmonary embolism protocol can be effectively reduced by the use of lead shielding.

  17. Radiation dose reduction in invasive cardiology by restriction to adequate instead of optimized picture quality.

    PubMed

    Kuon, Eberhard; Dorn, Christian; Schmitt, Moritz; Dahm, Johannes B

    2003-05-01

    In this study, the cinegraphic image intensifier entrance dose level for coronary angiography was changed in four steps from dose level A (0.041 microGy frame(-1)), allowing high contrast, but coarse mottled background, to level D (0.164 microGy frame(-1)), affording high transparency and sharpness. Using this new approach throughout the course of 404 consecutive cardiac catheterizations, we reduced patient radiation exposures down to 11 to 16% of currently typical values: i.e., mean dose area products of 5.97 Gy cm2 (n = 91), 6.73 (n = 113), 8.11 (n = 91), and 8.90 (n = 109); cinegraphic dose area products of 2.34, 3.64, 4.56, and 5.49; and cinegraphic dose area products frame(-1) of 13.3, 19.8, 27.0, and 30.2 mGy cm2, for levels A, B, C, and D, respectively. The number of cinegraphic frames ranged within 168 to 182 per case. Our results show that during catheterization interventionalists should vary image intensifier entrance dose levels in accordance with documented structure, angulation, and body mass index. With the exception of cases with special requirements, lower dose levels typically guarantee an adequate image quality.

  18. Noise reduction with low dose CT data based on a modified ROF model.

    PubMed

    Zhu, Yining; Zhao, Mengliu; Zhao, Yunsong; Li, Hongwei; Zhang, Peng

    2012-07-30

    In order to reduce the radiation exposure caused by Computed Tomography (CT) scanning, low dose CT has gained much interest in research as well as in industry. One fundamental difficulty for low dose CT lies in its heavy noise pollution in the raw data which leads to quality deterioration for reconstructed images. In this paper, we propose a modified ROF model to denoise low dose CT measurement data in light of Poisson noise model. Experimental results indicate that the reconstructed CT images based on measurement data processed by our model are in better quality, compared to the original ROF model or bilateral filtering.

  19. Evaluation of Antipsychotic Dose Reduction in Late-Life Schizophrenia: A Prospective Dopamine D2/3 Receptor Occupancy Study.

    PubMed

    Graff-Guerrero, Ariel; Rajji, Tarek K; Mulsant, Benoit H; Nakajima, Shinichiro; Caravaggio, Fernando; Suzuki, Takefumi; Uchida, Hiroyuki; Gerretsen, Philip; Mar, Wanna; Pollock, Bruce G; Mamo, David C

    2015-09-01

    Patients with late-life schizophrenia (LLS) are highly susceptible to antipsychotic adverse effects. Treatment guidelines endorse lower antipsychotic doses. However, the optimal dose of antipsychotics and associated dopamine D2/3 receptor (D2/3R) occupancies remain largely unexplored in patients with LLS. To evaluate effects of antipsychotic dose reduction on striatal dopamine D2/3R occupancies, clinical variables, and blood pharmacokinetic measures in patients with LLS. An open-label, single-arm prospective study with a 3- to 6-month follow-up period (January 10, 2007, to October 21, 2013) was conducted at an academic tertiary care center with practice for ambulatory care. Participants included 35 outpatients with clinically stable LLS (patients aged ≥ 50 years receiving olanzapine or risperidone monotherapy at the same dose for 6 to 12 months). Follow-up was completed on October 21, 2013, and analysis was conducted from October 22, 2014, to February 2, 2015. Carbon 11-labeled raclopride positron emission tomography, clinical measures, and blood pharmacokinetic measures performed before and after gradual dose reduction by up to 40% from the baseline dose and at least 3 months after dose reduction. Striatal dopamine D2/3R occupancies with antipsychotics, clinical measures (Positive and Negative Syndrome Scale, Brief Psychiatric Rating Scale, Targeted Inventory on Problems in Schizophrenia, Simpson-Angus Scale, Barnes Rating Scale for Drug-Induced Akathisia, Udvalg for Kliniske Undersøgelser Side Effect Rating Scale), and blood pharmacokinetic measures (prolactin and antipsychotic blood levels). Dopamine D2/3R occupancy of the entire sample decreased by a mean (SD) of 6.2% (8.2%) following dose reduction (from 70% [12%] to 64% [12%]; P < .001). The lowest D2/3R occupancy associated with clinical stability was 50%. Extrapyramidal symptoms (EPSs) were more likely to occur with D2/3R occupancies higher than 60%: 90.5% (19 of 21) of the participants with

  20. 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.

  1. Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans.

    PubMed

    Dauer, Lawrence T; Casciotta, Kevin A; Erdi, Yusuf E; Rothenberg, Lawrence N

    2007-03-16

    It is estimated that 60 million computed tomography (CT) scans were performed during 2006, with approximately 11% of those performed on children age 0-15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to assist the attending radiologist in the decision to utilize such male gonadal shields in pediatric imaging practice. The dose reduction to the gonads was measured for both direct radiation and for indirect scattered radiation from the abdomen. A 6 cm3 ion chamber (Model 10X5-6, Radcal Corporation, Monrovia, CA) was placed on a Humanoid real bone pelvic phantom at a position of the male gonads. When exposure measurements with shielding were made, a 1 mm lead wrap-around gonadal shield was placed around the ion chamber sensitive volume. The use of the shields reduced scatter dose to the gonads by a factor of about 2 with no appreciable loss of image quality. The shields reduced the direct beam dose by a factor of about 35 at the expense of extremely poor CT image quality due to severe streak artifacts. Images in the direct exposure case are not useful due to these severe artifacts and the difficulties in positioning these shields on patients in the scatter exposure case may not be warranted by the small absolute reduction in scatter dose unless it is expected that the patient will be subjected to numerous future CT scans.

  2. Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans

    PubMed Central

    Dauer, Lawrence T; Casciotta, Kevin A; Erdi, Yusuf E; Rothenberg, Lawrence N

    2007-01-01

    Background It is estimated that 60 million computed tomography (CT) scans were performed during 2006, with approximately 11% of those performed on children age 0–15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to assist the attending radiologist in the decision to utilize such male gonadal shields in pediatric imaging practice. Methods The dose reduction to the gonads was measured for both direct radiation and for indirect scattered radiation from the abdomen. A 6 cm3 ion chamber (Model 10X5-6, Radcal Corporation, Monrovia, CA) was placed on a Humanoid real bone pelvic phantom at a position of the male gonads. When exposure measurements with shielding were made, a 1 mm lead wrap-around gonadal shield was placed around the ion chamber sensitive volume. Results The use of the shields reduced scatter dose to the gonads by a factor of about 2 with no appreciable loss of image quality. The shields reduced the direct beam dose by a factor of about 35 at the expense of extremely poor CT image quality due to severe streak artifacts. Conclusion Images in the direct exposure case are not useful due to these severe artifacts and the difficulties in positioning these shields on patients in the scatter exposure case may not be warranted by the small absolute reduction in scatter dose unless it is expected that the patient will be subjected to numerous future CT scans. PMID:17367529

  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.

  4. 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.

  5. Prediction of Warfarin Dose Reductions in Puerto Rican Patients, Based on Combinatorial CYP2C9 and VKORC1 Genotypes

    PubMed Central

    Valentin, Isa Ivette; Vazquez, Joan; Rivera-Miranda, Giselle; Seip, Richard L; Velez, Meredith; Kocherla, Mohan; Bogaard, Kali; Cruz-Gonzalez, Iadelisse; Cadilla, Carmen L; Renta, Jessica Y; Felliu, Juan F; Ramos, Alga S; Alejandro-Cowan, Yirelia; Gorowski, Krystyna; Ruaño, Gualberto; Duconge, Jorge

    2012-01-01

    BACKGROUND The influence of CYP2C9 and VKORC1 polymorphisms on warfarin dose has been investigated in white, Asian, and African American populations but not in Puerto Rican Hispanic patients. OBJECTIVE To test the associations between genotypes, international normalized ratio (INR) measurements, and warfarin dosing and gauge the impact of these polymorphisms on warfarin dose, using a published algorithm. METHODS A retrospective warfarin pharmacogenetic association study in 106 Puerto Rican patients was performed. DNA samples from patients were assayed for 12 variants in both CYP2C9 and VKORC1 loci by HILOmet PhyzioType assay. Demographic and clinical nongenetic data were retrospectively collected from medical records. Allele and genotype frequencies were determined and Hardy-Weinberg equilibrium (HWE) was tested. RESULTS Sixty-nine percent of patients were carriers of at least one polymorphism in either the CYP2C9 or the VKORC1 gene. Double, triple, and quadruple carriers accounted for 22%, 5%, and 1%, respectively. No significant departure from HWE was found. Among patients with a given CYP2C9 genotype, warfarin dose requirements declined from GG to AA haplotypes; whereas, within each VKORC1 haplotype, the dose decreased as the number of CYP2C9 variants increased. The presence of these loss-of-function alleles was associated with more out-of-range INR measurements (OR = 1.38) but not with significant INR >4 during the initiation phase. Analyses based on a published pharmacogenetic algorithm predicted dose reductions of up to 4.9 mg/day in carriers and provided better dose prediction in an extreme subgroup of highly sensitive patients, but also suggested the need to improve predictability by developing a customized model for use in Puerto Rican patients. CONCLUSIONS This study laid important groundwork for supporting a prospective pharmacogenetic trial in Puerto Ricans to detect the benefits of incorporating relevant genomic information into a customized DNA

  6. Reduction in mutation frequency by very low-dose gamma irradiation of Drosophila melanogaster germ cells.

    PubMed

    Ogura, Keiji; Magae, Junji; Kawakami, Yasushi; Koana, Takao

    2009-01-01

    To determine whether the linear no-threshold (LNT) model for stochastic effects of ionizing radiation is applicable to very low-dose radiation at a low dose rate, we irradiated immature male germ cells of the fruit fly, Drosophila melanogaster, with several doses of (60)Co gamma rays at a dose rate of 22.4 mGy/h. Thereafter, we performed the sex-linked recessive lethal mutation assay by mating the irradiated males with nonirradiated females. The mutation frequency in the group irradiated with 500 microGy was found to be significantly lower than that in the control group (P < 0.01), whereas in the group subjected to 10 Gy irradiation, the mutation frequency was significantly higher than that in the control group (P < 0.03). A J-shaped dose-response relationship was evident. Molecular experiments using DNA microarray and quantitative reverse transcription PCR indicated that several genes known to be expressed in response to heat or chemical stress and grim, a positive regulator of apoptosis, were up-regulated immediately after irradiation with 500 microGy. The involvement of an apoptosis function in the non-linear dose-response relationship was suggested.

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

    PubMed

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

    2015-01-01

    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. 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). 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. 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.

  8. 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

  9. Reduction of bacterial titers by low-dose aspirin in experimental aortic valve endocarditis.

    PubMed Central

    Nicolau, D P; Freeman, C D; Nightingale, C H; Quintiliani, R; Coe, C J; Maderazo, E G; Cooper, B W

    1993-01-01

    Using a rabbit model of Staphylococcus aureus endocarditis, we studied the effects of aspirin on the natural progression of this infection. Compared with untreated animals, the aspirin-treated animals showed a 30% (P = 0.11) reduction in the weight of the vegetations and an 84% (P = 0.03) reduction in the bacterial titer of the vegetations. PMID:8454370

  10. 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.

  11. SU-D-209-03: Radiation Dose Reduction Using Real-Time Image Processing in Interventional Radiology

    SciTech Connect

    Kanal, K; Moirano, J; Zamora, D; Stewart, B

    2016-06-15

    Purpose: To characterize changes in radiation dose after introducing a new real-time image processing technology in interventional radiology systems. Methods: Interventional radiology (IR) procedures are increasingly complex, at times requiring substantial time and radiation dose. The risk of inducing tissue reactions as well as long-term stochastic effects such as radiation-induced cancer is not trivial. To reduce this risk, IR systems are increasingly equipped with dose reduction technologies.Recently, ClarityIQ (Philips Healthcare) technology was installed in our existing neuroradiology IR (NIR) and vascular IR (VIR) suites respectively. ClarityIQ includes real-time image processing that reduces noise/artifacts, enhances images, and sharpens edges while also reducing radiation dose rates. We reviewed 412 NIR (175 pre- and 237 post-ClarityIQ) procedures and 329 VIR (156 preand 173 post-ClarityIQ) procedures performed at our institution pre- and post-ClarityIQ implementation. NIR procedures were primarily classified as interventional or diagnostic. VIR procedures included drain port, drain placement, tube change, mesenteric, and implanted venous procedures. Air Kerma (AK in units of mGy) was documented for all the cases using a commercial radiation exposure management system. Results: When considering all NIR procedures, median AK decreased from 1194 mGy to 561 mGy. When considering all VIR procedures, median AK decreased from 49 to 14 mGy. Both NIR and VIR exhibited a decrease in AK exceeding 50% after ClarityIQ implementation, a statistically significant (p<0.05) difference. Of the 5 most common VIR procedures, all median AK values decreased, but significance (p<0.05) was only reached in venous access (N=53), angio mesenteric (N=41), and drain placement procedures (N=31). Conclusion: ClarityIQ can reduce dose significantly for both NIR and VIR procedures. Image quality was not assessed in conjunction with the dose reduction.

  12. SU-F-P-45: Clinical Experience with Radiation Dose Reduction of CT Examinations Using Iterative Reconstruction Algorithms

    SciTech Connect

    Weir, V; Zhang, J

    2016-06-15

    Purpose: Iterative reconstruction (IR) algorithms have been adopted by medical centers in the past several years. IR has a potential to substantially reduce patient dose while maintaining or improving image quality. This study characterizes dose reductions in clinical settings for CT examinations using IR. Methods: We retrospectively analyzed dose information from patients who underwent abdomen/pelvis CT examinations with and without contrast media in multiple locations of our Healthcare system. A total of 743 patients scanned with ASIR on 64 slice GE lightspeed VCTs at three sites, and 30 patients scanned with SAFIRE on a Siemens 128 slice Definition Flash in one site was retrieved. For comparison, patient data (n=291) from a GE scanner and patient data (n=61) from two Siemens scanners where filtered back-projection (FBP) was used was collected retrospectively. 30% and 10% ASIR, and SAFIRE Level 2 was used. CTDIvol, Dose-length-product (DLP), weight and height from all patients was recorded. Body mass index (BMI) was calculated accordingly. To convert CTDIvol to SSDE, AP and lateral dimensions at the mid-liver level was measured for each patient. Results: Compared with FBP, 30% ASIR reduces dose by 44.1% (SSDE: 12.19mGy vs. 21.83mGy), while 10% ASIR reduced dose by 20.6% (SSDE 17.32mGy vs. 21.83). Use of SAFIRE reduced dose by 61.4% (SSDE: 8.77mGy vs. 22.7mGy). The geometric mean for patients scanned with ASIR was larger than for patients scanned with FBP (geometric mean is 297.48 mmm vs. 284.76 mm). The same trend was observed for the Siemens scanner where SAFIRE was used (geometric mean: 316 mm with SAFIRE vs. 239 mm with FBP). Patient size differences suggest that further dose reduction is possible. Conclusion: Our data confirmed that in clinical practice IR can significantly reduce dose to patients who undergo CT examinations, while meeting diagnostic requirements for image quality.

  13. Radiation dose reduction in intra-arterial chemotherapy infusion for intraocular retinoblastoma.

    PubMed

    Cooke, Daniel L; Stout, Charles E; Kim, Warren T; Hetts, Steven W; Higashida, Randall T; Halbach, Van V; Dowd, Christopher F; Gould, Robert G

    2014-12-01

    Retinoblastoma (RB) is a rare malignancy affecting the pediatric population. Intravenous chemotherapy is the longstanding delivery method, although intra-arterial (IA) chemotherapy is gaining popularity given the reduced side effects compared with systemic chemotherapy administration. Given the sensitivity of the target organ, patient age, and secondary tumor susceptibility, a premium has been placed on minimizing procedural related radiation exposure. To reduce patient x-ray dose during the IA infusion procedure, customized surgical methods and fluoroscopic techniques were employed. The routine fluoroscopic settings were changed from the standard 7.5 pulses/s and dose level to the detector of 36 nGy/pulse, to a pulse rate of 4 pulses/s and detector dose to 23 nGy/pulse. The angiographic dose indicators (reference point air kerma (Ka) and fluoroscopy time) for a cohort of 10 consecutive patients (12 eyes, 30 infusions) were analyzed. An additional four cases (five eyes, five infusions) were analyzed using dosimeters placed at anatomic locations to reflect scalp, eye, and thyroid dose. The mean Ka per treated eye was 20.1±11.9 mGy with a mean fluoroscopic time of 8.5±4.6 min. Dosimetric measurements demonstrated minimal dose to the lens (0.18±0.10 mGy). Measured entrance skin doses varied from 0.7 to 7.0 mGy and were 73.4±19.7% less than the indicated Ka value. Ophthalmic arterial melphalan infusion is a safe and effective means to treat RB. Modification to contemporary fluoroscopic systems combined with parsimonious fluoroscopy can minimize radiation exposure. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. Role of compressive sensing technique in dose reduction for chest computed tomography: a prospective blinded clinical study.

    PubMed

    Khawaja, Ranish Deedar Ali; Singh, Sarabjeet; Lira, Diego; Bippus, Rolf; Do, Synho; Padole, Atul; Pourjabbar, Sarvenaz; Koehler, Thomas; Shepard, Jo-Anne; Kalra, Mannudeep K

    2014-01-01

    The purpose of this study was to assess pulmonary lesion detection, diagnostic confidence, and noise reduction in sparse-sampled (SpS) computed tomographic (CT) data of submillisievert (SubmSv) chest CT reconstructed with iterative reconstruction technique (IRT). This Human Insurance Portability and Accountability-compliant, institutional review board-approved prospective study was performed using SpS-SubmSv IRT chest CT in 10 non-obese patients (body-mass index, 21-35 kg/m; age range, 26-90 years). Written informed consent was obtained. The patients were scanned at standard-dose CT (mean [SD] volumetric CT dose index, 6 [0.9] mGy; mean [SD] dose-length product, 208 ± 44 mGy·cm; and mean [SD] effective dose, 3 [0.6] mSv) and at SubmSv dose (1.8 [0.2] mGy, 67 [2] mGy·cm, 0.9 [0.03] mSv, respectively) on a Philips 128-slice CT scanner with double z-sampling. Sparse angular sampling data were reconstructed using 25% of the angular projections from the SubmSv sinogram to reduce the number of views and radiation dose by approximately 4-fold. Hence, the patients were scanned and then, simulation-based sparse sampling was performed with a resultant dose hypothetical SpS scan estimated mathematically (0.2 mSv). From each patient data, 3 digital imaging and communications in medicine series were generated: SpS-SubmSv with IRT, fully sampled SubmSv filtered back projection (FBP), and fully sampled standard-dose FBP (SD-FBP). Two radiologists independently assessed these image series for detection of lung lesions, visibility of small structures, and diagnostic acceptability. Objective noise was measured in the thoracic aorta, and noise spectral density was obtained for SpS-SubmSv IRT, SubmSv-FBP, and SD-FBP. The SpS-SubmSv IRT resulted in 75% (0.2/0.9 mSv) and 92% (0.2/2.9 mSv) dose reduction, when compared with the fully sampled SubmSv-FBP and SD-FBP, respectively. Images of SpS-SubmSv displayed all 46 lesions (most <1 cm, 30 lung nodules, 7 ground glass opacities, 9

  15. 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.

  16. Effect of topogram-tube angle combination on CT radiation dose reduction

    NASA Astrophysics Data System (ADS)

    Shim, J.; Yoon, M.

    2017-09-01

    This study assessed the ability of various types of topograms, when used with an automatic tube current modulation (ATCM) technique, to reduce radiation dose from computed tomography (CT) scans. Three types of topograms were used with the ATCM technique: (i) anteroposterior (AP) topograms alone, (ii) AP topograms followed by lateral topograms, and (iii) lateral topograms followed by AP topograms. Various regions (chest, abdomen and whole-body) of a humanoid phantom were scanned at several tube voltages (80, 100 and 120 kVp) with the selected topograms. Although the CT dose depended on the order of topograms, the CT dose with respect to patient positioning depended on the number of topograms performed. The magnitude of the difference in CT dose between number and order of topograms was greater for the scans of the abdomen than the chest. These results suggest that, for the Siemens SOMATOM Definition AS CT scanner, choosing the right combination of CT scan conditions with the ATCM technique can minimize radiation dose to a patient.

  17. The reduction methods of operator's radiation dose for portable dental X-ray machines.

    PubMed

    Cho, Jeong-Yeon; Han, Won-Jeong

    2012-08-01

    This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

  18. Radiation Dose Reduction in Digital Plain Radiography of the Knee after Total Knee Arthroplasty.

    PubMed

    Kloth, J K; Tanner, M; Stiller, W; Burkholder, I; Kauczor, H U; Ewerbeck, V; Weber, M A

    2015-08-01

    To reduce radiation exposure of frequently performed radiographs of the knee in follow-up of total-knee arthroplasty ensuring accurate assessment by using objective quality control criteria. In this prospective randomized study 278 radiographs of the knee in follow-up of total-knee arthroplasty were performed with standard and 37% reduced radiation dose. The evaluation of the plain-radiographs was conducted using the following criteria: bone-implant interface, implant-surface character, implant-implant discrimination and periarticular heterotopic ossification. Two radiologists evaluated these criteria using a score ranging from 1 (definitely assessable) to 4 (not assessable). If a single criterion had been evaluated with a score ≥ 3 or more than 2 criteria with ≥ 2 points, the radiograph was score das "not assessable". The study was designed as non-inferiority-trial. 100% of examined radiographs were scored as assessable, hence no statistical inferiority between the examinations with standard and reduced dose could be observed. Singular assessment of the defined criteria was likewise dose-independent. Plain-radiography of the knee following total-knee arthroplasty can be performed with 63% of standard dose without loss of diagnostic validity. Due to the non-inferiority of digital radiographs of the knee joint after total-knee arthroplasty done with 37% reduced image receiver dose we recommend the tested speed class of SC 800 as a new reference value for digital radiographs with this indication. © Georg Thieme Verlag KG Stuttgart · New York.

  19. Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors.

    PubMed

    Yu, Tong; Gao, Jun; Liu, Zhi-Min; Zhang, Qi-Feng; Liu, Yong; Jiang, Ling; Peng, Yun

    2017-04-05

    Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors. Forty-five patients with solid tumors who had initial CT (Group B) and follow-up CT (Group A) after chemotherapy were enrolled. The initial diagnostic CT scan (Group B) was performed using the standard two-phase enhanced CT with 320 mgI/ml concentration contrast, and the follow-up scan (Group A) was performed using a single-phase enhanced CT at 45 s after the beginning of the 270 mgI/ml contrast injection using spectral mode. Forty percent ASiR was used for the images in Group B and monochromatic images with energy levels ≥60 keV in Group A. In addition, filtered back-projection (FBP) reconstruction was used for monochromatic images <60 keV in Group A. The total radiation dose, total iodine load, contrast injection speed, and maximum injection pressure were compared between the two groups. The 40 keV and 60 keV spectral CT images of Group A were compared with the images of Group B to evaluate overall image quality. The total radiation dose, total iodine load, injection speed, and maximum injection pressure for Group A were decreased by 19%, 15%, 34.4%, and 18.3%, respectively. The optimal energy level in spectral CT for displaying the abdominal vessels was 40 keV. At this level, the CT values in the abdominal aorta and its three branches, the portal vein and its two branches, and the inferior vena cava were all greater than 340 hounsfield unit (HU). The abdominal organs of Groups A and B had similar degrees of absolute and relative enhancement (t = 0.36 and -1.716 for liver, -0.153 and

  20. A New Design of a Lead-Acrylic Shield for Staff Dose Reduction in Radial and Femoral Access Coronary Catheterization.

    PubMed

    Eder, H; Seidenbusch, M C; Treitl, M; Gilligan, P

    2015-10-01

    Today's standard radiation protection during coronary angiography and percutaneous coronary interventions is the combined use of lead acrylic shields and table-mounted lower body protection. Ambient dose measurements, however, have shown that these protection devices need improvement. Using an anthropomorphic physical phantom, various scenarios were investigated with respect to personnel exposure: a) enlarging the shield b) adding a flexible protective curtain to the bottom side of the shield, and c) application of radioprotective patient drapes. For visualization of the dose reduction effect, Monte Carlo simulations were performed. The flexible curtain in contact with the patient's body reduces the ambient dose rate at the operator's position by up to (87.5% ± 7.1) compared to the situation with the bare shield. The use of both the flexible curtain and the patient drape reduces the ambient dose rate by up to (90.8% ± 7). Similar results were achieved for the assisting personnel when they were positioned next to the operator. In addition, the enlarged shield provides better protection of the head region of tall operators. Adding a flexible protective curtain to the bottom side of the shield can protect operators from high doses, especially for body parts which are not protected by lead aprons, e.g. head, and eye lenses. This may be important with respect to lower dose limits for eye lenses in future. The protective effect in real-life working conditions is still being evaluated in an ongoing clinical study. Lead acrylic shields need improvement for a better protection of head and eye lenses. An additional flexible lead curtain at the bottom of the shield can considerably reduce the operator dose. Using the additional lead curtain, lighter protection clothing can be worn. Special eye protection may be no longer needed in most applications. © Georg Thieme Verlag KG Stuttgart · New York.

  1. 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.

  2. Lead versus bismuth-antimony shield for fetal dose reduction at different gestational ages at CT pulmonary angiography.

    PubMed

    Chatterson, Leslie C; Leswick, David A; Fladeland, Derek A; Hunt, Megan M; Webster, Stephen T

    2011-08-01

    To compare the effective fetal dose reduction at different stages of gestation during maternal computed tomographic (CT) pulmonary angiography by using traditional lead apron and bismuth-antimony shields combined with limited z-axis and tube current. Phantom with gravid prosthesis, 0.5-mm lead, and two grades of bismuth-antimony shield was used. Thermoluminescent dosimeters (TLDs) measured radiation in the first- to third-trimester uterus. Fetal dose was determined for each gestation by using 100 kVp to the costophrenic angles (CPAs) with and without shielding for a total of 12 scans. Eight third-trimester scans were used to compare shields using 120 kVp to CPAs versus those using 100 kVp to the diaphragm. Average fetal dose increased with gestation with use of 100 kVp to CPAs, from 0.11 mGy in first trimester to 0.50 mGy in third trimester. Average third-trimester unshielded fetal dose was reduced from 0.82 mGy by using 120 kVp to CPAs to 0.17 mGy (79%, P < .001) by using 100 kVp to the diaphragm. Lead apron reduced dose more than either of the bismuth-antimony shields (72%-79% vs 57%-81%) with use of 100 kVp to CPAs. Shields reduced the dose by 73% (lead), 62% (90% attenuation bismuth-antimony), and 72% (95% attenuation bismuth-antimony) (P < .01) at 120 kVp to CPAs. No significant difference between shields was demonstrated with 100 kVp to the diaphragm (P < .01). Maternal dose was 8.13 mSv at 120 kVp to CPAs, 4.90 mSv at 100 kVp to CPAs, and 4.02 mSv at 100 kVp to the diaphragm. Reducing voltage and limiting z-axis is more effective than shields at reducing fetal dose. Shielding improves reduction with no significant difference between lead and bismuth-antimony shields when conservative scanning parameters are observed. © RSNA, 2011.

  3. 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

  4. X-ray dose reduction using additional copper filtration for abdominal digital radiography: Evaluation using signal difference-to-noise ratio.

    PubMed

    Kawashima, Hiroki; Ichikawa, Katsuhiro; Nagasou, Daisuke; Hattori, Masayuki

    2017-02-01

    X-ray dose reduction using additional copper filters (Cu-filters) for abdominal general radiography was indicated in a report using a simulation study. We validated the dose reduction effects using a clinical digital radiography system equipped with an indirect-type CsI detector and an automatic Cu-filter insertion function. The image qualities were evaluated using signal difference-to-noise ratio (SDNR) for different radiation qualities with and without Cu-filters for a 20-cm acrylic phantom. Acrylic and bone equivalent material plates were used for contrast measurements. The dose reduction using Cu-filters was estimated from the ratios of the SDNR(2) values. For the same entrance surface dose (ESD), Cu-filters with 0.1- and 0.2-mm thicknesses increased the image quality as evaluated by SDNR(2) and the estimated dose reduction without degrading the image quality. For the acrylic contrast, the dose reductions with the 0.1- and 0.2-mm-thick Cu-filters were approximately 30% and 44% at 70kV and 29% and 35% at 80kV, respectively. For the bone contrast, the reduction rates were slightly reduced. We validated the dose reduction capability of additional Cu-filters without degrading the image quality for abdominal radiography. The estimated entrance surface dose reductions of the Cu-filters were approximately 30-40% and 20-30% for the acrylic and bone contrasts, respectively, and effective dose reductions for acrylic were nearly half of those for ESD. At these reduced dose conditions, the current time product values needed to be increased by factors of 1.4 and 1.8 for the 0.1- and 0.2-mm-thick Cu-filters, respectively. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  5. Current opinions on medical radiation: a survey of oncologists regarding radiation exposure and dose reduction in oncology patients.

    PubMed

    Burke, Lauren M B; Bashir, Mustafa R; Neville, Amy M; Nelson, Rendon C; Jaffe, Tracy A

    2014-05-01

    The aim of this study was to evaluate oncologists' opinions about the use of ionizing radiation in medical imaging of oncology patients. An electronic survey was e-mailed to 2,725 oncologists at the top 50 National Cancer Institute-funded cancer centers. The survey focused on opinions on CT dose reduction in oncology patients and current philosophies behind long-term imaging in these patients. The response rate was 15% (415 of 2,725). Eighty-two percent of respondents stated that their patients or families have expressed anxiety regarding radiation dose from medical imaging. Although fewer than half of oncologists (48%) did not know whether CT dose reduction techniques were used at their institutions, only 25% were concerned that small lesions may be missed with low-dose CT techniques. The majority of oncologists (63%) follow National Comprehensive Cancer Network guidelines for imaging follow-up, while the remainder follow other national guidelines such as those of the Children's Oncology Group, the American Society of Clinical Oncology, or clinical trials. Ninety percent of respondents believe that long-term surveillance in oncology patients is warranted, particularly in patients with breast cancer, melanoma, sarcoma, and pediatric malignancies. The majority of oncologists would consider the use of low-dose CT imaging in specific patient populations: (1) children and young women, (2) those with malignancies that do not routinely metastasize to the liver, and (3) patients undergoing surveillance imaging. Cumulative radiation exposure is a concern for patients and oncologists. Among oncologists, there is support for long-term imaging surveillance despite lack of national guidelines. Published by Elsevier Inc.

  6. Accuracy and Radiation Dose Reduction of Limited-Range CT in the Evaluation of Acute Appendicitis in Pediatric Patients.

    PubMed

    Jin, Michael; Sanchez, Thomas R; Lamba, Ramit; Fananapazir, Ghaneh; Corwin, Michael T

    2017-09-01

    The purpose of this article is to determine the accuracy and radiation dose reduction of limited-range CT prescribed from the top of L2 to the top of the pubic symphysis in children with suspected acute appendicitis. We performed a retrospective study of 210 consecutive pediatric patients from December 11, 2012, through December 11, 2014, who underwent abdominopelvic CT for suspected acute appendicitis. Two radiologists independently reviewed the theoretic limited scans from the superior L2 vertebral body to the top of the pubic symphysis, to assess for visualization of the appendix, acute appendicitis, alternative diagnoses, and incidental findings. Separately, the same parameters were assessed on the full scan by the same two reviewers. Whole-body effective doses were determined for the full- and limited-range scans and were compared using the paired t test. The appendix or entire cecum was visualized on the limited scan in all cases, and no cases of acute appendicitis were missed on the simulated limited scan compared with the full scan. Two alternative diagnoses were missed with the limited scan: one case of hydronephrosis and one of acute acalculous cholecystitis. The mean effective dose for the original scan was 5.6 mSv and that for the simulated limited scan was 3.0 mSv, resulting in a dose reduction of 46.4% (p < 0.001). A limited-range CT examination performed from the top of L2 to the top of the pubic symphysis is as accurate as a full-range abdominopelvic CT in evaluating pediatric patients with suspected appendicitis and reduces the dose by approximately 46%.

  7. Radiation therapy for early stage unfavorable Hodgkin lymphoma: is dose reduction feasible?

    PubMed

    Laskar, Siddhartha; Kumar, Deepak P; Khanna, Nehal; Menon, Hari; Sengar, Manju; Arora, Brijesh; Gujral, Sumeet; Shet, Tanuja; Sridhar, Epari; Rangarajan, Venkatesh; Muckaden, Mary Ann; Nair, Reena; Banavali, Shripad

    2014-10-01

    One hundred and fifty-one patients aged between 3 and 70 years with early stage unfavorable Hodgkin lymphoma were included. Patients received 4-6 cycles of ABVD (doxorubicin, bleomycin, vinblastine and dacarbazine) chemotherapy and involved field radiation therapy (IFRT). The most common histology was mixed cellularity (43%). The majority had stage IIAX disease. IFRT doses were 25.2 Gy/14 fractions and 34.2 Gy/19 fractions for adults with a complete response (CR) and partial response (PR), respectively, while the doses were 19.8 Gy/11 fractions and 30.6 Gy/17 fractions, respectively, for children. After 60 months (median), the 10-year progression-free survival (PFS) and overall survival (OS) were 88.4% and 93.2%, respectively. On univariate analysis, prognostic factors with significant impact on PFS were age ≥ 18 years, nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) histology, extranodal disease and response to treatment. Extranodal disease had a significant impact on OS. On multivariate analysis, NLPHL histology (p = 0.001) and response at 3 months (p = 0.000) had a significant impact on PFS. There were no in-field relapses in patients with bulky disease receiving RT doses > 25.2 Gy. Chemotherapy related acute pulmonary toxicity was documented in 21.4% and 4.8% of patients after six and four cycles of ABVD chemotherapy (p = 0.041). Four cycles of ABVD and reduced dose IFRT resulted in optimal outcomes.

  8. Reduction of the rectal dose in gynecological brachytherapy: modification to the Fletcher-Suit applicator.

    PubMed

    Rosenblatt, E; Cederbaum, M; Yereslav, N; Kuten, A

    1996-01-01

    The dose to the anterior rectal wall is a known limiting factor for the delivery of radical doses of radiation to the uterine cervix with brachytherapy. We developed a modification to the Fletcher-Suit afterloading applicator, consisting of two small inflatable balloons attached to the posterior end of each colpostat. The balloons are connected to catheters that emerge from the vagina attached to the colpostat's handles. The balloons were affixed to the colpostats with a plastic adaptor and are inserted empty. After an anterior radiograph is taken, the balloons are filled with radiological contrast material and a lateral orthogonal film is made. This lateral film taken with the balloons filled with contrast typically shows a significant posterior displacement of the anterior rectal wall away from the vaginal sources. The International Commission on Radiation Units (ICRU) rectal point is then determined 5 mm beyond the posterior boundary of the opacified balloons. We have performed 90 applications using this device, including brachytherapy applications for cervical cancer, as well as vaginal applications for endometrial carcinoma following TAH-BSO. On average, the ICRU rectal point was displaced 14 mm away from the colpostats, thus reducing the dose rate by 60% and resulting in an average dose sparing of about 1000 cGy to the anterior rectal wall.

  9. Radiation dose reduction in computed tomography perfusion using spatial-temporal Bayesian methods

    NASA Astrophysics Data System (ADS)

    Fang, Ruogu; Raj, Ashish; Chen, Tsuhan; Sanelli, Pina C.

    2012-03-01

    In current computed tomography (CT) examinations, the associated X-ray radiation dose is of significant concern to patients and operators, especially CT perfusion (CTP) imaging that has higher radiation dose due to its cine scanning technique. A simple and cost-effective means to perform the examinations is to lower the milliampere-seconds (mAs) parameter as low as reasonably achievable in data acquisition. However, lowering the mAs parameter will unavoidably increase data noise and degrade CT perfusion maps greatly if no adequate noise control is applied during image reconstruction. To capture the essential dynamics of CT perfusion, a simple spatial-temporal Bayesian method that uses a piecewise parametric model of the residual function is used, and then the model parameters are estimated from a Bayesian formulation of prior smoothness constraints on perfusion parameters. From the fitted residual function, reliable CTP parameter maps are obtained from low dose CT data. The merit of this scheme exists in the combination of analytical piecewise residual function with Bayesian framework using a simpler prior spatial constrain for CT perfusion application. On a dataset of 22 patients, this dynamic spatial-temporal Bayesian model yielded an increase in signal-tonoise-ratio (SNR) of 78% and a decrease in mean-square-error (MSE) of 40% at low dose radiation of 43mA.

  10. Reduction of (18)F-FDG Dose in Clinical PET/MR Imaging by Using Silicon Photomultiplier Detectors.

    PubMed

    Sekine, Tetsuro; Delso, Gaspar; Zeimpekis, Konstantinos G; de Galiza Barbosa, Felipe; Ter Voert, Edwin E G W; Huellner, Martin; Veit-Haibach, Patrick

    2017-09-14

    Purpose To determine the level of clinically acceptable reduction in injected fluorine 18 ((18)F) fluorodeoxyglucose (FDG) dose in time-of-flight (TOF)-positron emission tomography(PET)/magnetic resonance (MR) imaging by using silicon photomultiplier (SiPM) detectors compared with TOF-PET/computed tomography (CT) using Lu1.8Y0.2SiO5(Ce), or LYSO, detectors in patients with different body mass indexes (BMIs). Materials and Methods Patients were enrolled in this study as part of a larger prospective study with a different purpose than evaluated in this study (NCT02316431). All patients gave written informed consent prior to inclusion into the study. In this study, 74 patients with different malignant diseases underwent sequential whole-body TOF-PET/CT and TOF-PET/MR imaging. PET images with simulated reduction of injected (18)F-FDG doses were generated by unlisting the list-mode data from PET/MR imaging. Two readers rated the image quality of whole-body data sets, as well as the image quality in each body compartment, and evaluated the conspicuity of malignant lesions. Results The image quality with 70% or 60% of the injected dose of (18)F-FDG at PET/MR imaging was comparable to that at PET/CT. With 50% of the injected dose, comparable image quality was maintained among patients with a BMI of less than 25 kg/m(2). PET images without TOF reconstruction showed higher artifact scores and deteriorated sharpness than those with TOF reconstruction. Conclusion Sixty percent of the usually injected (18)F-FDG dose (reduction of up to 40%) in patients with a BMI of more than 25 kg/m(2) results in clinically adequate PET image quality in TOF-PET/MR imaging performed by using SiPM detectors. Additionally, in patients with a BMI of less than 25 kg/m(2), 50% of the injected dose may safely be used. (©) RSNA, 2017 Online supplemental material is available for this article.

  11. Reduction of operator radiation dose by an extended lower body shield.

    PubMed

    Gonzales, John P; Moran, Christopher; Silberzweig, James E

    2014-03-01

    To quantify the reduction in operator exposure to scatter radiation by using an extension component in addition to a commonly used lower body radiation shield attached to an interventional radiology procedure table. An anthropomorphic pelvis phantom was exposed to fluoroscopy at varying C-arm angles to simulate a standard interventional procedure. A MAVIG UT60 lower body shield (MAVIG, Munich, Germany) (48 cm × 78 cm, 0.5 mm lead equivalent), with an attachable extension component (48 cm × 36 cm), was suspended from the edge of the table adjacent to the pelvic phantom. Using a handheld Geiger counter, scatter radiation exposure rates were measured at the level of an operator's eye, chest, waist, and knee, with various C-arm angles both with and without the attachable extension component. Mean exposure rates for each experimental setup were calculated and compared. Overall, scatter radiation exposures were lower with the addition of the extension component, with the largest reductions (> 80%) measured at the operator's waist and knee levels, for all C-arm angles. The highest reduction in scatter radiation exposure was measured at knee level, at 0 degrees left posterior oblique projection, where the use of the lower body shield extension component reduced the exposure rate from 4.80 mR/h to 0.44 mR/h (90.8% reduction, P < .001). Reductions in scatter radiation were less at eye and chest levels. The use of the additional extension component to the lower body radiation shield can result in large (> 80%) reductions in operator scatter radiation exposure, particularly to the lower body. © 2014 SIR Published by SIR All rights reserved.

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

    PubMed Central

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

    2012-01-01

    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, ΔD, 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 125I seeds. The breast case consisted of 87 Model-200 103Pd 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 D90, 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 × 1 × 1 mm3 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 heterogeneous doses

  13. Analysis and reduction of thermal dose errors in MRgFUS treatment.

    PubMed

    Zucconi, Fabio; Colombo, Paola E; Pasetto, Stefano; Lascialfari, Alessandro; Ticca, Cristiana; Torresin, Alberto

    2014-02-01

    ExAblate 2000 MRgFUS system (InSightec) installed in Ospedale Maggiore Niguarda Ca' Granda (Milano, Italy) is currently used to treat uterine fibroids. Through the magnetic resonance thermometry (PRF method), it is possible to monitor the temperature in the target in real-time and compute the treated region calculating the thermal dose. The purpose of this work is to investigate the errors in the temperature measurements and their effect on thermal dose. A low pass filtering of temperature maps is proposed to reduce the errors and therefore to improve the reliability of the treated regions calculated. The PRF method was studied through a calibration experiment on ex vivo pig muscle. The outcome resulted to be a very good linearity (p value 0.03) between phase and temperature in the range of interest, and an α value of -0.0109 ± 0.0002 ppm/°C. Temperature statistical uncertainty was evaluated by analyzing the temperature readout variability in specific gel provided by InSightec for daily quality assurance control. It resulted to be 1.89 ± 0.32 °C. A Monte Carlo simulation of the MRI temperature measurement and thermal dose calculations in our specific conditions of geometry and statistical uncertainty revealed that a low-pass filtering process on each temperature map can strongly reduce systematic errors in thermal dose evaluations (1.11 overestimation factor instead of 2.62 without filter); consequently the systematic errors on the size of the predicted ablated area are reduced as well.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. Reduction in radiation doses from paediatric CT scans in Great Britain.

    PubMed

    Lee, Choonsik; Pearce, Mark S; Salotti, Jane A; Harbron, Richard W; Little, Mark P; McHugh, Kieran; Chapple, Claire-Louise; Berrington de Gonzalez, Amy

    2016-01-01

    Although CT scans provide great medical benefits, concerns have been raised about the magnitude of possible associated cancer risk, particularly in children who are more sensitive to radiation than adults. Unnecessary high doses during CT examinations can also be delivered to children, if the scan parameters are not adjusted for patient age and size. We conducted the first survey to directly assess the trends in CT scan parameters and doses for paediatric CT scans performed in Great Britain between 1978 and 2008. We retrieved 1073 CT film sets from 36 hospitals. The patients were 0-19 years old, and CT scans were conducted between 1978 and 2008. We extracted scan parameters from each film including tube current-time product [milliampere seconds (mAs)], tube potential [peak kilovoltage (kVp)] and manufacturer and model of the CT scanner. We estimated the mean mAs for head and trunk (chest and abdomen/pelvis) scans, according to patient age (0-4, 5-9, 10-14 and 15-19 years) and scan year (<1990, 1990-1994, 1995-1999 and ≥2000), and then derived the volumetric CT dose index and estimated organ doses. For head CT scans, mean mAs decreased by about 47% on average from before 1990 to after 2000, with the decrease starting around 1990. The mean mAs for head CTs did not vary with age before 1990, whereas slightly lower mAs values were used for younger patients after 1990. Similar declines in mAs were observed for trunk CTs: a 46% decline on an average from before 1990 to after 2000. Although mean mAs for trunk CTs did not vary with age before 1990, the value varied markedly by age, from 63 mAs for age 0-4 years compared with 315 mAs for those aged >15 years after 2000. No material changes in kVp were found. Estimated brain-absorbed dose from head CT scans decreased from 62 mGy before 1990 to approximately 30 mGy after 2000. For chest CT scans, the lung dose to children aged 0-4 years decreased from 28 mGy before 1990 to 4 mGy after 2000. We found that mAs for

  19. 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.

  20. 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.

  1. Comparison of fluoro and cine coronary angiography: balancing acceptable outcomes with a reduction in radiation dose.

    PubMed

    Olcay, Ayhan; Guler, Ekrem; Karaca, Ibrahim Oguz; Omaygenc, Mehmet Onur; Kizilirmak, Filiz; Olgun, Erkam; Yenipinar, Esra; Cakmak, Huseyin Altug; Duman, Dursun

    2015-04-01

    Use of last fluoro hold (LFH) mode in fluoroscopy, which enables the last live image to be saved and displayed, could reduce radiation during percutaneous coronary intervention when compared with cine mode. No previous study compared coronary angiography radiation doses and image quality between LFH and conventional cine mode techniques. We compared cumulative dose-area product (DAP), cumulative air kerma, fluoroscopy time, contrast use, interobserver variability of visual assessment between LFH angiography, and conventional cine angiography techniques. Forty-six patients were prospectively enrolled into the LFH group and 82 patients into the cine angiography group according to operator decision. Mean cumulative DAP was higher in the cine group vs the LFH group (50058.98 ± 53542.71 mGy•cm² vs 11349.2 ± 8796.46 mGy•cm²; P<.001). Mean fluoroscopy times were higher in the cine group vs the LFH group (3.87 ± 5.08 minutes vs 1.66 ± 1.51 minutes; P<.01). Mean contrast use was higher in the cine group vs the LFH group (112.07 ± 43.79 cc vs 88.15 ± 23.84 cc; P<.001). Mean value of Crombach's alpha was not statistically different between visual estimates of three operators between cine and LFH angiography groups (0.66680 ± 0.19309 vs 0.54193 ± 0.31046; P=.20). Radiation doses, contrast use, and fluoroscopy times are lower in fluoroscopic LFH angiography vs cine angiography. Interclass variability of visual stenosis estimation between three operators was not different between cine and LFH groups. Fluoroscopic LFH images conventionally have inferior diagnostic quality when compared with cine coronary angiography, but with new angiographic systems with improved LFH image quality, these images may be adequate for diagnostic coronary angiography.

  2. Simultaneous reduction of radiation dose and scatter for CBCT by using collimators

    SciTech Connect

    Li, Tianfang; Li, Xiang; Yang, Yong; Zhang, Yongqian; Heron, Dwight E.; Huq, M. Saiful

    2013-12-15

    Purpose: On-board cone-beam CT (CBCT) imaging has been widely available in radiotherapy clinic for target localization. However, the extra radiation dose from CBCT is always a concern for its frequent use. Additionally, the relatively large scatter in CBCT often degrades the image quality. By using collimators, some of the X-rays can be stopped from reaching the patient and the detectors, hence both the scatter and the patient doses are simultaneously reduced. The authors show in this work that the collimated CBCT data can be reconstructed without any noticeable artifacts for certain collimator blocking ratios and blocking patterns, and the focus of this work is to study the relationship between the image quality and these two collimator factors.Methods: A CBCT system with collimators was simulated following the typical geometry used in clinic. Different collimator designs were tested by varying the size and the number of the collimator slits, and at the same time, the ratio of transmitted beams to total beams was varied from 100% to 10%, resulting in hundreds of different simulation scenarios. Lung and pelvis phantoms created from patients CT images were used in the simulations, and an iterative reconstruction algorithm using the compressed sensing technique was adopted. The image quality was examined by root mean square errors (RMSEs) and compared with the conventional CBCT images.Results: The CBCT image quality increases as the amount of beams passing through the collimators increases, and decreases as the size of the collimator slits increases. With ultra-high resolution collimators, the RMSEs were comparable to the conventional CBCT image quality until the beam transmission rate is reduced below 25%.Conclusions: Collimators can reduce the scatters and radiation dose, however, the collimated CBCT image quality is strongly dependent on both the collimator blocking ratio and the blocking pattern. To achieve image quality comparable to the conventional CBCT, the

  3. 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.

  4. Radiation dose reduction with application of non-linear adaptive filters for abdominal CT

    PubMed Central

    Singh, Sarabjeet; Kalra, Mannudeep K; Sung, Mi Kim; Back, Anni; Blake, Michael A

    2012-01-01

    AIM: To evaluate the effect of non-linear adaptive filters (NLAF) on abdominal computed tomography (CT) images acquired at different radiation dose levels. METHODS: Nineteen patients (mean age 61.6 ± 7.9 years, M:F = 8:11) gave informed consent for an Institutional Review Board approved prospective study involving acquisition of 4 additional image series (200, 150, 100, 50 mAs and 120 kVp) on a 64 slice multidetector row CT scanner over an identical 10 cm length in the abdomen. The CT images acquired at 150, 100 and 50 mAs were processed with the NLAF. Two radiologists reviewed unprocessed and processed images for image quality in a blinded randomized manner. CT dose index volume, dose length product, patient weight, transverse diameters, objective noise and CT numbers were recorded. Data were analyzed using Analysis of Variance and Wilcoxon signed rank test. RESULTS: Of the 31 lesions detected in abdominal CT images, 28 lesions were less than 1 cm in size. Subjective image noise was graded as unacceptable in unprocessed images at 50 and 100 mAs, and in NLAF processed images at 50 mAs only. In NLAF processed images, objective image noise was decreased by 21% (14.4 ± 4/18.2 ± 4.9) at 150 mAs, 28.3% (15.7 ± 5.6/21.9 ± 4) at 100 mAs and by 39.4% (18.8 ± 9/30.4 ± 9.2) at 50 mAs compared to unprocessed images acquired at respective radiation dose levels. At 100 mAs the visibility of smaller structures improved from suboptimal in unprocessed images to excellent in NLAF processed images, whereas diagnostic confidence was respectively improved from probably confident to fully confident. CONCLUSION: NLAF lowers image noise, improves the visibility of small structures and maintains lesion conspicuity at down to 100 mAs for abdominal CT. PMID:22328968

  5. Is weight-based adjustment of automatic exposure control necessary for the reduction of chest CT radiation dose?

    PubMed

    Prakash, Priyanka; Kalra, Mannudeep K; Gilman, Matthew D; Shepard, Jo-Anne O; Digumarthy, Subba R

    2010-01-01

    To assess the effects of radiation dose reduction in the chest CT using a weight-based adjustment of the automatic exposure control (AEC) technique. With Institutional Review Board Approval, 60 patients (mean age, 59.1 years; M:F = 35:25) and 57 weight-matched patients (mean age, 52.3 years, M:F = 25:32) were scanned using a weight-adjusted AEC and non-weight-adjusted AEC, respectively on a 64-slice multidetector CT with a 0.984:1 pitch, 0.5 second rotation time, 40 mm table feed/rotation, and 2.5 mm section thickness. Patients were categorized into 3 weight categories; < 60 kg (n = 17), 60-90 kg (n = 52), and > 90 kg (n = 48). Patient weights, scanning parameters, CT dose index volumes (CTDIvol) and dose length product (DLP) were recorded, while effective dose (ED) was estimated. Image noise was measured in the descending thoracic aorta. Data were analyzed using a standard statistical package (SAS/STAT) (Version 9.1, SAS institute Inc, Cary, NC). Compared to the non-weight-adjusted AEC, the weight-adjusted AEC technique resulted in an average decrease of 29% in CTDIvol and a 27% effective dose reduction (p < 0.0001). With weight-adjusted AEC, the CTDIvol decreased to 15.8, 15.9, and 27.3 mGy for the < 60, 60-90 and > 91 kg weight groups, respectively, compared to 20.3, 27.9 and 32.8 mGy, with non-weight-adjusted AEC. No significant difference was observed for objective image noise between the chest CT acquired with the non-weight-adjusted (15.0 +/- 3.1) and weight-adjusted (16.1 +/- 5.6) AEC techniques (p > 0.05). The results of this study suggest that AEC should be tailored according to patient weight. Without weight-based adjustment of AEC, patients are exposed to a 17 - 43% higher radiation-dose from a chest CT.

  6. Quantification of radiation dose reduction by reducing z-axis coverage in 320-detector coronary CT angiography.

    PubMed

    Murphy, David J; Keraliya, Abhishek; Himes, Nathan; Aghayev, Ayaz; Blankstein, Ron; Steigner, Michael L

    2017-08-01

    To quantify the radiation dose reduction achievable by minimizing z-axis coverage in 320-detector coronary CT angiography (CCTA). We retrospectively reviewed 130 CCTAs performed on 320-detector CT that offers up to 16 cm z-axis coverage (adjustable in 2-cm increments), allowing complete coverage of the heart in a single gantry rotation. For each CT, we obtained the radiation dose [CT dose index and dose-length product (DLP)], measured the z-axis field of view and measured the craniocaudal cardiac size (distance from the left main coronary artery to the cardiac apex). We calculated the radiation dose savings achievable by reducing the z-axis coverage to the minimum necessary to cover the heart using 320 × 0.5-mm (maximum 16 cm) and 256 × 0.5-mm (maximum 12.8 cm) detector collimations. Results are expressed as mean ± standard deviation. The mean craniocaudal cardiac size was 10.5 ± 1.0 cm, with 85% (n = 112) of CCTAs performed with 16 cm of z-axis coverage. The mean DLP was 417.6 ± 182.4 mGy cm, with the mean DLP saving achievable using the minimum z-axis coverage required to completely image the heart being 96.2 ± 47.4 mGy cm, an average dose reduction of 26.9 ± 7.0%. z-axis coverage of ≤12 cm was adequate for 92% and 12.8 cm for 98% of subjects. Using the minimal z-axis coverage to adequately image the heart is a simple step that can reduce the DLP in 320-detector CCTA by approximately 27%. z-axis coverage of ≤12 cm is adequate for 92%, 12.8 cm for 98% and 14 cm for 100% of patients undergoing CCTA. Advances in knowledge: Reducing z-axis coverage in 320-detector CCTA can reduce DLP by approximately 27%.

  7. Performance of adaptive iterative dose reduction 3D integrated with automatic tube current modulation in radiation dose and image noise reduction compared with filtered-back projection for 80-kVp abdominal CT: Anthropomorphic phantom and patient study.

    PubMed

    Chen, Chien-Ming; Lin, Yang-Yu; Hsu, Ming-Yi; Hung, Chien-Fu; Liao, Ying-Lan; Tsai, Hui-Yu

    2016-09-01

    Evaluate the performance of Adaptive Iterative Dose Reduction 3D (AIDR 3D) and compare with filtered-back projection (FBP) regarding radiation dosage and image quality for an 80-kVp abdominal CT. An abdominal phantom underwent four CT acquisitions and reconstruction algorithms (FBP; AIDR 3D mild, standard and strong). Sixty-three patients underwent unenhanced liver CT with FBP and standard level AIDR 3D. Further post-acquisition reconstruction with strong level AIDR 3D was made. Patients were divided into two groups (< and ≧29cm) based on the abdominal effective diameter (Deff) at T12 level. Quantitative (attenuation, noise, and signal-to-noise ratio) and qualitative (image quality, noise, sharpness, and artifact) analysis by two readers were assessed and the interobserver agreement was calculated. Strong level AIDR 3D reduced radiation dose by 72% in the phantom and 47.1% in the patient study compared with FBP. There was no difference in mean attenuations. Image noise was the lowest and signal-to-noise ratio the highest using strong level AIDR 3D in both patient groups. For Deff<29cm, image sharpness of FBP was significantly different from those of AIDR 3D (P<0.05). For Deff ≧29cm, image quality of AIDR 3D was significantly more favorable than FBP (P<0.05). Interobserver agreement was substantial. Integrated AIDR 3D allows for an automatic reduction in radiation dose and maintenance of image quality compared with FBP. Using AIDR 3D reconstruction, patients with larger abdomen circumference could be imaged at 80kVp. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. SU-F-18C-15: Model-Based Multiscale Noise Reduction On Low Dose Cone Beam Projection

    SciTech Connect

    Yao, W; Farr, J

    2014-06-15

    Purpose: To improve image quality of low dose cone beam CT for patient positioning in radiation therapy. Methods: In low dose cone beam CT (CBCT) imaging systems, Poisson process governs the randomness of photon fluence at x-ray source and the detector because of the independent binomial process of photon absorption in medium. On a CBCT projection, the variance of fluence consists of the variance of noiseless imaging structure and that of Poisson noise, which is proportional to the mean (noiseless) of the fluence at the detector. This requires multiscale filters to smoothen noise while keeping the structure information of the imaged object. We used a mathematical model of Poisson process to design multiscale filters and established the balance of noise correction and structure blurring. The algorithm was checked with low dose kilo-voltage CBCT projections acquired from a Varian OBI system. Results: From the investigation of low dose CBCT of a Catphan phantom and patients, it showed that our model-based multiscale technique could efficiently reduce noise and meanwhile keep the fine structure of the imaged object. After the image processing, the number of visible line pairs in Catphan phantom scanned with 4 ms pulse time was similar to that scanned with 32 ms, and soft tissue structure from simulated 4 ms patient head-and-neck images was also comparable with scanned 20 ms ones. Compared with fixed-scale technique, the image quality from multiscale one was improved. Conclusion: Use of projection-specific multiscale filters can reach better balance on noise reduction and structure information loss. The image quality of low dose CBCT can be improved by using multiscale filters.

  9. Fludarabine Allows Dose Reduction for Total Body Irradiation in Pediatric Hematopoietic Stem Cell Transplantation

    SciTech Connect

    Kornguth, David G. . E-mail: dkorngut@mdanderson.org; Mahajan, Anita; Woo, Shiao; Chan, Ka Wah; Antolak, John; Ha, Chul S.

    2007-07-15

    Purpose: To examine, in the setting of total body irradiation (TBI) for the preparation of pediatric hematopoietic stem cell transplantation (HSCT), whether TBI dose can be reduced without compromising the efficacy of a regimen consisting of fludarabine and radiotherapy; and whether there is any increased risk of pulmonary toxicity due to the radiosensitizing effect of fludarabine. Methods and Materials: A total of 52 pediatric patients with hematologic malignancies received TBI-based conditioning regimens in preparation for allogeneic HSCT. Twenty-three patients received 12 Gy in 4 daily fractions in combination with cyclophosphamide, either alone or with other chemotherapeutic and biologic agents. Twenty-nine patients received 9 Gy in 3 fractions in conjunction with fludarabine and melphalan. Clinical and radiation records were reviewed to determine engraftment, pulmonary toxicity (according to Radiation Therapy Oncology Group criteria), transplant-related mortality, recurrence of primary disease, and overall survival. Results: The two groups of patients had comparable pretransplant clinical characteristics. For the 12-Gy and 9-Gy regimens, the engraftment (89% and 93%; p = 0.82), freedom from life-threatening pulmonary events (65% and 79%; p = 0.33), freedom from relapse (60% and 73%; p = 0.24), and overall survival (26% and 47%; p = 0.09) were not statistically different. Conclusions: The addition of fludarabine and melphalan seems to allow the dose of TBI to be lowered to 9 Gy without loss of engraftment or antitumor efficacy.

  10. A multiscale filter for noise reduction of low-dose cone beam projections

    NASA Astrophysics Data System (ADS)

    Yao, Weiguang; Farr, Jonathan B.

    2015-08-01

    The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, \\text{exp}≤ft(-{{x}2}/2σ f2\\right) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of {σf} , which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ f2 is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

  11. Reduction in stray radiation dose using a body-shielding device during external radiation therapy.

    PubMed

    Zhang, Shuxu; Jiang, Shaohui; Zhang, Quanbin; Lin, Shengqu; Wang, Ruihao; Zhou, Xiang; Zhang, Guoqian; Lei, Huaiyu; Yu, Hui

    2017-03-01

    With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD. In addition, SRDs in anterior, posterior, left and right directions of phantom were investigated with and without shielding, respectively. Also, the SRD at the bottom of treatment couch was measured. SRD decreased exponentially to a constant value with increasing distance from field edge. The shielding rate was 50%-80%; however, there were no significant differences in SRDs when shielded by 1 mm lead, 2 mm lead, or 1 mm lead plus 10 mm bolus (P>0.05). Importantly, the 10 mm bolus absorbed back-scattering radiation due to the interaction between photons and lead. As a result, 1 mm lead plus 10 mm bolus was selected to prepare the BSD. After shielding with BSD, total SRDs in the OFR decreased to almost 50% of those without shielding when irradiated with IMRT beams. Due to the effects of treatment couch and gantry angle, SRDs at distances were not identical in anterior, posterior, left and right direction of phantom without BSD. As higher dose in anterior and lower dose in posterior, SRDs were substantial similarities after shielding. There was no significant difference in SRDs for left and right directions with or without shielding. Interestingly, SRDs in the four directions were similar after shielding. From these results, the BSD developed in this study may significantly reduce SRD in the OFR during

  12. A multiscale filter for noise reduction of low-dose cone beam projections.

    PubMed

    Yao, Weiguang; Farr, Jonathan B

    2015-08-21

    The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, exp(-x2/2σ(2)(f)) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of σ(f), which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ(2)(f)) is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

  13. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 7

    SciTech Connect

    Kaurin, D.G.; Khan, T.A.; Sullivan, S.G.; Baum, J.W.

    1993-07-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in the continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This is volume 7 of the series. The abstracts in this bibliography were selected from proceedings of technical meetings and conferences, journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to radiation protection and dose reduction, and ranges from use of robotics to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 7 contains 293 abstract, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 7. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes.

  14. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 8

    SciTech Connect

    Sullivan, S.G.; Khan, T.A.; Xie, J.W.

    1995-05-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in a continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This volume 8 of the series. The abstracts in this bibliography were selected form proceedings of technical meetings and conference journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to the many aspects of radiation protection and dose reduction, and ranges form use of robotics, to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 8 contains 232 abstracts, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 8. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes.

  15. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study.

    PubMed

    Sabarudin, Akmal; Mustafa, Zakira; Nassir, Khadijah Mohd; Hamid, Hamzaini Abdul; Sun, Zhonghua

    2015-01-01

    This phantom study was designed to compare the radiation dose in thoracic and abdomen-pelvic CT scans with and without use of tube current modulation (TCM). Effective dose (ED) and size-specific dose estimation (SSDE) were calculated with the absorbed doses measured at selective radiosensitive organs using a thermoluminescence dosimeter-100 (TLD-100). When compared to protocols without TCM, the ED and SSDE were reduced significantly with use of TCM for both the thoracic and abdomen-pelvic CT. With use of TCM, the ED was 6.50±0.29 mSv for thoracic and 6.01±0.20 mSv for the abdomen-pelvic CT protocols. However without use of TCM, the ED was 20.07±0.24 mSv and 17.30±0.41 mSv for the thoracic and abdomen-pelvic CT protocols, respectively. The corresponding SSDE was 10.18±0.48 mGy and 11.96±0.27 mGy for the thoracic and abdomen-pelvic CT protocols with TCM, and 31.56±0.43 mGy and 33.23±0.05 mGy for thoracic and abdomen-pelvic CT protocols without TCM, respectively. The highest absorbed dose was measured at the breast with 8.58±0.12 mGy in the TCM protocols and 51.52±14.72 mGy in the protocols without TCM during thoracic CT. In the abdomen-pelvic CT, the absorbed dose was highest at the skin with 9.30±1.28 mGy and 29.99±2.23 mGy in protocols with and without use of TCM, respectively. In conclusion, the TCM technique results in significant dose reduction; thus it is to be highly recommended in routine thoracic and abdomen-pelvic CT. PACS numbers: 87.57.Q-, 87.57.qp, 87.53.Bn.

  16. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study.

    PubMed

    Sabarudin, Akmal; Mustafa, Zakira; Nassir, Khadijah Mohd; Hamid, Hamzaini Abdul; Sun, Zhonghua

    2014-01-08

    This phantom study was designed to compare the radiation dose in thoracic and abdomen-pelvic CT scans with and without use of tube current modulation (TCM). Effective dose (ED) and size-specific dose estimation (SSDE) were calculated with the absorbed doses measured at selective radiosensitive organs using a thermoluminescence dosimeter-100 (TLD-100). When compared to protocols without TCM, the ED and SSDE were reduced significantly with use of TCM for both the thoracic and abdomen-pelvic CT. With use of TCM, the ED was 6.50 ± 0.29 mSv for thoracic and 6.01 ± 0.20 mSv for the abdomen-pelvic CT protocols. However without use of TCM, the ED was 20.07 ± 0.24 mSv and 17.30 ± 0.41 mSv for the thoracic and abdomen-pelvic CT protocols, respectively. The corresponding SSDE was 10.18 ± 0.48 mGy and 11.96 ± 0.27 mGy for the thoracic and abdomen-pelvic CT protocols with TCM, and 31.56 ± 0.43 mGy and 33.23 ± 0.05 mGy for thoracic and abdomen-pelvic CT protocols without TCM, respectively. The highest absorbed dose was measured at the breast with 8.58 ± 0.12 mGy in the TCM protocols and 51.52 ± 14.72 mGy in the protocols without TCM during thoracic CT. In the abdomen-pelvic CT, the absorbed dose was highest at the skin with 9.30 ± 1.28mGy and 29.99 ± 2.23 mGy in protocols with and without use of TCM, respectively. In conclusion, the TCM technique results in significant dose reduction; thus it is to be highly recommended in routine thoracic and abdomen-pelvic CT.

  17. Radiation dose reduction in the evaluation of scoliosis: an application of digital radiography

    SciTech Connect

    Kushner, D.C.; Cleveland, R.H.; Herman, T.E.; Zaleske, D.J.; Ehrlich, M.G.; Correia, J.A.

    1986-10-01

    This report documents the clinical testing of scanning beam digital radiography as an imaging method in patients with scoliosis. This type of digital imaging requires a skin exposure of only 2.4 mR (0.619 microC/kg) per image, compared with the lowest possible posteroanterior screen-film exposure of 10 mR (2.58 microC/kg) at the chest and 60 mR (15.48 microC/kg) at the lumbar spine. Digital radiographic and screen-film images were obtained on multiple test objects and 273 patients. Scoliosis measurements using screen-film radiographs and digital radiographs were comparable to within a mean difference of 1 degrees at many different degrees of severity. The low-dose digital images were found to be useful and accurate for the detection and measurement of scoliosis after the first screen-film radiographs have excluded tumors and structural abnormalities.

  18. Reducing an already low dental diagnostic X-ray dose: does it make sense? Comparison of three cost-utility analysis methods used to assess two dental dose-reduction measures.

    PubMed

    Hoogeveen, R C; Sanderink, G C H; van der Stelt, P F; Berkhout, W E R

    2015-01-01

    To find a method that is suitable for providing an objective assessment of the cost effectiveness of a dose-reducing measure used for diagnostic dental X-ray exposures. Three cost-utility analysis (CUA) methods were evaluated by comparing their assessments of two dose-reduction measures, a rectangular collimator and the combination of two devices that reduce the radiation dose received during orthodontic lateral cephalography. The following CUA methods were used: (1) the alpha value (AV), a monetary valuation of dose reduction used in the nuclear industry; (2) the value of a statistical life for valuation of the reduction in stochastic adverse effects; and (3) the time-for-time method, based on the postulate that risk reduction is effective when the number of years of life gained is more than the years that an average worker must work to earn the costs of the risk-reducing measure. The CUA methods were used to determine the minimum number of uses that was required for the dose-reducing device to be cost effective. The methods were assessed for coherence (are comparable results achieved for comparable countries?) and adaptability (can the method be adjusted for age and gender of specific patient groups?). The performance of the time-for-time method was superior to the other methods. Both types of dose-reduction devices tested were assessed as cost effective after a realistic number of uses with all three methods except low AVs. CUA for the methods of X-ray dose reduction can be performed to determine if investment in low dose reduction is cost effective. The time-for-time method proved to be a coherent and versatile method for performing CUA.

  19. Reducing an already low dental diagnostic X-ray dose: does it make sense? Comparison of three cost-utility analysis methods used to assess two dental dose-reduction measures

    PubMed Central

    Sanderink, G C H; van der Stelt, P F; Berkhout, W E R

    2015-01-01

    Objectives: To find a method that is suitable for providing an objective assessment of the cost effectiveness of a dose-reducing measure used for diagnostic dental X-ray exposures. Methods: Three cost–utility analysis (CUA) methods were evaluated by comparing their assessments of two dose-reduction measures, a rectangular collimator and the combination of two devices that reduce the radiation dose received during orthodontic lateral cephalography. The following CUA methods were used: (1) the alpha value (AV), a monetary valuation of dose reduction used in the nuclear industry; (2) the value of a statistical life for valuation of the reduction in stochastic adverse effects; and (3) the time-for-time method, based on the postulate that risk reduction is effective when the number of years of life gained is more than the years that an average worker must work to earn the costs of the risk-reducing measure. The CUA methods were used to determine the minimum number of uses that was required for the dose-reducing device to be cost effective. The methods were assessed for coherence (are comparable results achieved for comparable countries?) and adaptability (can the method be adjusted for age and gender of specific patient groups?). Results: The performance of the time-for-time method was superior to the other methods. Both types of dose-reduction devices tested were assessed as cost effective after a realistic number of uses with all three methods except low AVs. Conclusions: CUA for the methods of X-ray dose reduction can be performed to determine if investment in low dose reduction is cost effective. The time-for-time method proved to be a coherent and versatile method for performing CUA. PMID:26119214

  20. Short-term malaria reduction by single-dose azithromycin during mass drug administration for trachoma, Tanzania.

    PubMed

    Schachterle, Stephen E; Mtove, George; Levens, Joshua P; Clemens, Emily; Shi, Lirong; Raj, Amrita; Dumler, J Stephen; Munoz, Beatriz; West, Shelia; Sullivan, David J

    2014-06-01

    Single-dose mass drug administration of azithromycin (AZT) is underway to eliminate trachoma worldwide. Studies in Ethiopia showed a reduction in all-cause childhood deaths after administration. To examine the effect of single-dose AZ MDA on prevalent malaria infections in a large prospective cohort of children and parents in Dodoma Province, Tanzania, we quantified the temporal prevalence of malaria parasitemia by real-time PCR for 6 months after single-dose AZT. In the first month after treatment but not in subsequent months, Plasmodium falciparum infections were reduced by 73% (95% CI 43%-89%) in treatment versus control villages and differences remained significant (p = 0.00497) in multivariate models with village-level random effects. Genetic sequencing of P. falciparum ribosomal L4 protein showed no mutations associated with AZT resistance. AZT mass drug administration caused a transient, 1-month antimalarial effect without selecting for P. falciparum ribosomal L4 resistance mutations in a region with a 10-year history of treating trachoma with this drug.

  1. Reduction in Radiation Dose in a Pediatric Cardiac Catheterization Lab Using the Philips AlluraClarity X-ray System.

    PubMed

    Sullivan, Patrick M; Harrison, David; Badran, Sarah; Takao, Cheryl M; Ing, Frank F

    2017-08-02

    The objective of this study was to compare radiation doses and imaging quality using Philips AlluraClarity (Philips Healthcare, Best, The Netherlands) X-ray system and an older generation reference system. AlluraClarity is a new generation fluoroscopy system designed to reduce radiation without compromising image quality, but reports of its use in pediatric patients are limited. Dose area products (DAP, mGy cm(2)) and DAP/kg were compared in patients catheterized using Allura Xper and AlluraClarity systems over a year of use for each. Randomly selected studies from each system were assessed for image quality. The 430 patients imaged with Clarity were larger than the 332 imaged with Xper (median BSA: 0.74 vs. 0.64 m(2), p = 0.06), and median total fluoroscopic times (TFT) were similar (15.8 vs. 16.1 min, p = 0.37). Median DAPs were 8661 mGy cm(2) (IQR: 18,300 mGy cm(2)) and 4523 mGy cm(2) (IQR: 11,596 mGy cm(2)) with Xper and Clarity, respectively (p < 0.001). There was a reduction in median DAP in all procedure categories. After adjustment for BSA, TFT, and procedure type, using Clarity was associated with a 57.5% (95% CI 51.5-62.8%, p < 0.001) reduction in DAP for all procedures. Reductions did not significantly differ by weight (<10 kg, 10-40 kg, ≥ 40 kg). There was an adjusted percent reduction in DAP for each procedure category ranging from 39.0% (95% CI 25.6-50.1%, p < 0.001) for cardiac biopsies with or without coronary angiography to 67.6% (95% CI 61.2-72.8%, p < 0.001) for device occlusions. Mean overall imaging quality scores (4.3 ± 0.8 with Clarity vs. 4.4 ± 0.6 with Xper, p = 0.62) and scores based on specific quality parameters were similar in the two groups. Use of AlluraClarity substantially reduced radiation doses compared to the older generation reference system without compromising imaging quality in a pediatric cardiac catheterization lab.

  2. Noise correlation in CBCT projection data and its application for noise reduction in low-dose CBCT

    SciTech Connect

    Zhang, Hua; Ouyang, Luo; Wang, Jing E-mail: jing.wang@utsouthwestern.edu; Ma, Jianhua E-mail: jing.wang@utsouthwestern.edu; Huang, Jing; Chen, Wufan

    2014-03-15

    Purpose: To study the noise correlation properties of cone-beam CT (CBCT) projection data and to incorporate the noise correlation information to a statistics-based projection restoration algorithm for noise reduction in low-dose CBCT. Methods: In this study, the authors systematically investigated the noise correlation properties among detector bins of CBCT projection data by analyzing repeated projection measurements. The measurements were performed on a TrueBeam onboard CBCT imaging system with a 4030CB flat panel detector. An anthropomorphic male pelvis phantom was used to acquire 500 repeated projection data at six different dose levels from 0.1 to 1.6 mAs per projection at three fixed angles. To minimize the influence of the lag effect, lag correction was performed on the consecutively acquired projection data. The noise correlation coefficient between detector bin pairs was calculated from the corrected projection data. The noise correlation among CBCT projection data was then incorporated into the covariance matrix of the penalized weighted least-squares (PWLS) criterion for noise reduction of low-dose CBCT. Results: The analyses of the repeated measurements show that noise correlation coefficients are nonzero between the nearest neighboring bins of CBCT projection data. The average noise correlation coefficients for the first- and second-order neighbors are 0.20 and 0.06, respectively. The noise correlation coefficients are independent of the dose level. Reconstruction of the pelvis phantom shows that the PWLS criterion with consideration of noise correlation (PWLS-Cor) results in a lower noise level as compared to the PWLS criterion without considering the noise correlation (PWLS-Dia) at the matched resolution. At the 2.0 mm resolution level in the axial-plane noise resolution tradeoff analysis, the noise level of the PWLS-Cor reconstruction is 6.3% lower than that of the PWLS-Dia reconstruction. Conclusions: Noise is correlated among nearest neighboring

  3. Effects of a radiation dose reduction strategy for computed tomography in severely injured trauma patients in the emergency department: an observational study

    PubMed Central

    2011-01-01

    Background Severely injured trauma patients are exposed to clinically significant radiation doses from computed tomography (CT) imaging in the emergency department. Moreover, this radiation exposure is associated with an increased risk of cancer. The purpose of this study was to determine some effects of a radiation dose reduction strategy for CT in severely injured trauma patients in the emergency department. Methods We implemented the radiation dose reduction strategy in May 2009. A prospective observational study design was used to collect data from patients who met the inclusion criteria during this one year study (intervention group) from May 2009 to April 2010. The prospective data were compared with data collected retrospectively for one year prior to the implementation of the radiation dose reduction strategy (control group). By comparison of the cumulative effective dose and the number of CT examinations in the two groups, we evaluated effects of a radiation dose reduction strategy. All the patients met the institutional adult trauma team activation criteria. The radiation doses calculated by the CT scanner were converted to effective doses by multiplication by a conversion coefficient. Results A total of 118 patients were included in this study. Among them, 33 were admitted before May 2009 (control group), and 85 were admitted after May 2009 (intervention group). There were no significant differences between the two groups regarding baseline characteristics, such as injury severity and mortality. Additionally, there was no difference between the two groups in the mean number of total CT examinations per patient (4.8 vs. 4.5, respectively; p = 0.227). However, the mean effective dose of the total CT examinations per patient significantly decreased from 78.71 mSv to 29.50 mSv (p < 0.001). Conclusions The radiation dose reduction strategy for CT in severely injured trauma patients effectively decreased the cumulative effective dose of the total CT

  4. Detection of parathyroid adenomas using a monophasic dual-energy computed tomography acquisition: diagnostic performance and potential radiation dose reduction.

    PubMed

    Leiva-Salinas, Carlos; Flors, Lucia; Durst, Christopher R; Hou, Qinghua; Patrie, James T; Wintermark, Max; Mukherjee, Sugoto

    2016-11-01

    The aims of the study were to compare the diagnostic performance of a combination of virtual non-contrast (VNC) images and arterial images obtained from a single-phase dual-energy CT (DECT) acquisition and standard non-contrast and arterial images from a biphasic protocol and to study the potential radiation dose reduction of the former approach. All DECT examinations performed for evaluation of parathyroid adenomas during a 13-month period were retrospectively reviewed. An initial single-energy unenhanced acquisition was followed by a dual-energy arterial phase acquisition. "Virtual non-contrast images" were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated three different sets of images during three reading sessions: single arterial phase, single-phase DECT (virtual non-contrast and arterial phase), and standard biphasic protocol (true non-contrast and arterial phase). The accuracy of interpretation in lateralizing an adenoma to the side of the neck and localizing it to a quadrant in the neck was evaluated. Sixty patients (mean age, 65.5 years; age range, 38-87 years) were included in the study. The lateralization and localization accuracy, sensitivity, and positive predicted value (PPV) and negative predicted value (NPV) of the different image datasets were comparable. The combination of VNC and arterial images was more specific than arterial images alone to lateralize a parathyroid lesion (OR = 1.93, p = 0.043). The use of the single-phase protocol resulted in a calculated radiation exposure reduction of 52.8 %. Virtual non-contrast and arterial images from a single DECT acquisition showed similar diagnostic accuracy than a biphasic protocol, providing a significant dose reduction.

  5. In vitro evaluation of a new iterative reconstruction algorithm for dose reduction in coronary artery calcium scoring.

    PubMed

    Gassenmaier, Tobias; Allmendinger, Thomas; Kunz, Andreas S; Veyhl-Wichmann, Maike; Ergün, Süleyman; Bley, Thorsten A; Petritsch, Bernhard

    2017-05-01

    Coronary artery calcium (CAC) scoring is a widespread tool for cardiac risk assessment in asymptomatic patients and accompanying possible adverse effects, i.e. radiation exposure, should be as low as reasonably achievable. To evaluate a new iterative reconstruction (IR) algorithm for dose reduction of in vitro coronary artery calcium scoring at different tube currents. An anthropomorphic calcium scoring phantom was scanned in different configurations simulating slim, average-sized, and large patients. A standard calcium scoring protocol was performed on a third-generation dual-source CT at 120 kVp tube voltage. Reference tube current was 80 mAs as standard and stepwise reduced to 60, 40, 20, and 10 mAs. Images were reconstructed with weighted filtered back projection (wFBP) and a new version of an established IR kernel at different strength levels. Calcifications were quantified calculating Agatston and volume scores. Subjective image quality was visualized with scans of an ex vivo human heart. In general, Agatston and volume scores remained relatively stable between 80 and 40 mAs and increased at lower tube currents, particularly in the medium and large phantom. IR reduced this effect, as both Agatston and volume scores decreased with increasing levels of IR compared to wFBP (P < 0.001). Depending on selected parameters, radiation dose could be lowered by up to 86% in the large size phantom when selecting a reference tube current of 10 mAs with resulting Agatston levels close to the reference settings. New iterative reconstruction kernels may allow for reduction in tube current for established Agatston scoring protocols and consequently for substantial reduction in radiation exposure.

  6. In vitro evaluation of a new iterative reconstruction algorithm for dose reduction in coronary artery calcium scoring

    PubMed Central

    Allmendinger, Thomas; Kunz, Andreas S; Veyhl-Wichmann, Maike; Ergün, Süleyman; Bley, Thorsten A; Petritsch, Bernhard

    2017-01-01

    Background Coronary artery calcium (CAC) scoring is a widespread tool for cardiac risk assessment in asymptomatic patients and accompanying possible adverse effects, i.e. radiation exposure, should be as low as reasonably achievable. Purpose To evaluate a new iterative reconstruction (IR) algorithm for dose reduction of in vitro coronary artery calcium scoring at different tube currents. Material and Methods An anthropomorphic calcium scoring phantom was scanned in different configurations simulating slim, average-sized, and large patients. A standard calcium scoring protocol was performed on a third-generation dual-source CT at 120 kVp tube voltage. Reference tube current was 80 mAs as standard and stepwise reduced to 60, 40, 20, and 10 mAs. Images were reconstructed with weighted filtered back projection (wFBP) and a new version of an established IR kernel at different strength levels. Calcifications were quantified calculating Agatston and volume scores. Subjective image quality was visualized with scans of an ex vivo human heart. Results In general, Agatston and volume scores remained relatively stable between 80 and 40 mAs and increased at lower tube currents, particularly in the medium and large phantom. IR reduced this effect, as both Agatston and volume scores decreased with increasing levels of IR compared to wFBP (P < 0.001). Depending on selected parameters, radiation dose could be lowered by up to 86% in the large size phantom when selecting a reference tube current of 10 mAs with resulting Agatston levels close to the reference settings. Conclusion New iterative reconstruction kernels may allow for reduction in tube current for established Agatston scoring protocols and consequently for substantial reduction in radiation exposure. PMID:28607763

  7. Corneal Dose Reduction Using a Bismuth-Coated Latex Shield over the Eyes During Brain SPECT/CT.

    PubMed

    Matsutomo, Norikazu; Fukunaga, Masaaki; Onishi, Hideo; Yamamoto, Tomoaki

    2017-09-01

    This study aimed to determine whether a bismuth-coated latex shield (B-shield) could protect the eyes during brain SPECT/CT. Methods: A shield containing the heavy metal bismuth (equivalent to a 0.15-mm-thick lead shield) was placed over a cylindric phantom and the eyes of a 3-dimensional brain phantom filled with (99m)Tc solution. Subsequently, phantoms with and without the B-shield were compared using SPECT/CT. The CT parameters were 30-200 mA and 130 kV. The dose reduction achieved by the B-shield was measured using a pencil-shaped ionization chamber. The protective effects of the B-shield were determined by evaluating relative radioactivity concentration as well as artifacts (changes in CT number), linear attenuation coefficients, and coefficients of variation on SPECT images. Results: The radiation doses with and without the B-shield were 0.14-0.77 and 0.36-1.93 mGy, respectively, and the B-shield decreased the average radiation dose by about 60%. The B-shield also increased the mean CT number, but only at locations just beneath the surface of the phantom. Streaks of higher density near the underside of the B-shield indicated beam hardening. Linear attenuation coefficients and the coefficients of variation did not significantly differ between phantoms with and without the B-shield, and the relative (99m)Tc radioactivity concentrations were not affected. Conclusion: The B-shield decreased the radiation dose without affecting estimated attenuation correction or radioactivity concentrations. Although surface artifacts increased with the B-shield, the quality of the SPECT images was acceptable. B-shields can help protect pediatric patients and patients with eye diseases who undergo SPECT imaging. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  8. Reductions in carotid chemoreceptor activity with low-dose dopamine improves baroreflex control of heart rate during hypoxia in humans.

    PubMed

    Mozer, Michael T; Holbein, Walter W; Joyner, Michael J; Curry, Timothy B; Limberg, Jacqueline K

    2016-07-01

    The purpose of the present investigation was to examine the contribution of the carotid body chemoreceptors to changes in baroreflex control of heart rate with exposure to hypoxia. We hypothesized spontaneous cardiac baroreflex sensitivity (scBRS) would be reduced with hypoxia and this effect would be blunted when carotid chemoreceptor activity was reduced with low-dose dopamine. Fifteen healthy adults (11 M/4 F) completed two visits randomized to intravenous dopamine or placebo (saline). On each visit, subjects were exposed to 5-min normoxia (~99% SpO2), followed by 5-min hypoxia (~84% SpO2). Blood pressure (intra-arterial catheter) and heart rate (ECG) were measured continuously and scBRS was assessed by spectrum and sequence methodologies. scBRS was reduced with hypoxia (P < 0.01). Using the spectrum analysis approach, the fall in scBRS with hypoxia was attenuated with infusion of low-dose dopamine (P < 0.01). The decrease in baroreflex sensitivity to rising pressures (scBRS "up-up") was also attenuated with low-dose dopamine (P < 0.05). However, dopamine did not attenuate the decrease in baroreflex sensitivity to falling pressures (scBRS "down-down"; P > 0.05). Present findings are consistent with a reduction in scBRS with systemic hypoxia. Furthermore, we show this effect is partially mediated by the carotid body chemoreceptors, given the fall in scBRS is attenuated when activity of the chemoreceptors is reduced with low-dose dopamine. However, the improvement in scBRS with dopamine appears to be specific to rising blood pressures. These results may have important implications for impairments in baroreflex function common in disease states of acute and/or chronic hypoxemia, as well as the experimental use of dopamine to assess such changes.

  9. [State of the art and future trends in technology for computed tomography dose reduction].

    PubMed

    Calzado Cantera, A; Hernández-Girón, I; Salvadó Artells, M; Rodríguez González, R

    2013-12-01

    The introduction of helical and multislice acquisitions in CT scanners together with decreased image reconstruction times has had a tremendous impact on radiological practice. Technological developments in the last 10 to 12 years have enabled very high quality images to be obtained in a very short time. Improved image quality has led to an increase in the number of indications for CT. In parallel to this development, radiation exposure in patients has increased considerably. Concern about the potential health risks posed by CT imaging, reflected in diverse initiatives and actions by official organs and scientific societies, has prompted the search for ways to reduce radiation exposure in patients without compromising diagnostic efficacy. To this end, good practice guidelines have been established, special applications have been developed for scanners, and research has been undertaken to optimize the clinical use of CT. Noteworthy technical developments incorporated in scanners include the different modes of X-ray tube current modulation, automatic selection of voltage settings, selective organ protection, adaptive collimation, and iterative reconstruction. The appropriate use of these tools to reduce radiation doses requires thorough knowledge of how they work. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.

  10. Design and functionalities of the MADOR® software suite for dose-reduction management after DTPA therapy.

    PubMed

    Leprince, B; Fritsch, P; Bérard, P; Roméo, P-H

    2016-03-01

    A software suite on biokinetics of radionuclides and internal dosimetry intended for the occupational health practitioners of nuclear industry and for expert opinions has been developed under Borland C++ Builder™. These computing tools allow physicians to improve the dosimetric follow-up of workers in agreement with the French regulations and to manage new internal contaminations by radionuclides such as Pu and/or Am after diethylene triamine penta-acetic acid treatments. In this paper, the concept and functionalities of the first two computing tools of this MADOR(®) suite are described. The release 0.0 is the forensic application, which allows calculating the derived recording levels for intake by inhalation or ingestion of the main radioisotopes encountered in occupational environment. Indeed, these reference values of activity are convenient to interpret rapidly the bioassay measurements and make decisions as part of medical monitoring. The release 1.0 addresses the effect of DTPA treatments on Pu/Am biokinetics and the dose benefit. The forensic results of the MADOR(®) suite were validated by comparison with reference data. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Toward a dose reduction strategy using model-based reconstruction with limited-angle tomosynthesis

    NASA Astrophysics Data System (ADS)

    Haneda, Eri; Tkaczyk, J. E.; Palma, Giovanni; Iordache, Rǎzvan; Zelakiewicz, Scott; Muller, Serge; De Man, Bruno

    2014-03-01

    Model-based iterative reconstruction (MBIR) is an emerging technique for several imaging modalities and appli- cations including medical CT, security CT, PET, and microscopy. Its success derives from an ability to preserve image resolution and perceived diagnostic quality under impressively reduced signal level. MBIR typically uses a cost optimization framework that models system geometry, photon statistics, and prior knowledge of the recon- structed volume. The challenge of tomosynthetic geometries is that the inverse problem becomes more ill-posed due to the limited angles, meaning the volumetric image solution is not uniquely determined by the incom- pletely sampled projection data. Furthermore, low signal level conditions introduce additional challenges due to noise. A fundamental strength of MBIR for limited-views and limited-angle is that it provides a framework for constraining the solution consistent with prior knowledge of expected image characteristics. In this study, we analyze through simulation the capability of MBIR with respect to prior modeling components for limited-views, limited-angle digital breast tomosynthesis (DBT) under low dose conditions. A comparison to ground truth phantoms shows that MBIR with regularization achieves a higher level of fidelity and lower level of blurring and streaking artifacts compared to other state of the art iterative reconstructions, especially for high contrast objects. The benefit of contrast preservation along with less artifacts may lead to detectability improvement of microcalcification for more accurate cancer diagnosis.

  12. Reduction of aspirin-induced fecal blood loss with low-dose misoprostol tablets in man

    SciTech Connect

    Cohen, M.M.; Clark, L.; Armstrong, L.; D'Souza, J.

    1985-07-01

    Misoprostol (SC-29333), a synthetic prostaglandin E1 methyl ester analog, was given simultaneously with acetylsalicylic acid in a double-blind, placebo-controlled randomized prospective study of 32 healthy human male subjects. Fecal blood loss was measured for eight days using the /sup 51/Cr-labeled red blood cell technique. Aspirin (650 mg qid) and misoprostol (25 micrograms qid) or placebo were given during days 3, 4, and 5. There was a significant (P less than 0.05) increase in median blood loss (modified Friedman test) from 0.81 to 6.05 ml/day in the aspirin with placebo group (N = 16). Median blood loss was increased (from 0.75 to 3.75 ml/day) in the aspirin with misoprostol group (N = 16), but this was significantly less (Mann-Whitney U test, P less than 0.01) than the placebo group. Mean serum salicylate concentrations in the placebo and misoprostol groups were similar (7.8 and 6.8 micrograms/ml, respectively). There were no significant changes in laboratory values in any of the subjects studied, nor were any major side-effects encountered. This study demonstrates that oral misoprostol reduces aspirin-induced gastrointestinal bleeding even when administered simultaneously and at a dose level below its threshold for significant acid inhibition. This indicates a potential role for misoprostol in the prevention of gastric mucosal damage in selected patients.

  13. Quantification and reduction of peripheral dose from leakage radiation on Siemens Primus accelerators in electron therapy mode.

    PubMed

    Yeboah, Collins; Karotki, Alex; Hunt, Dylan; Holly, Rick

    2010-06-15

    In this work, leakage radiation from EA200 series electron applicators on Siemens Primus accelerators is quantified, and its penetration ability in water and/or the shielding material Xenolite-NL established. Initially, measurement of leakage from 10 x 10 - 25 x 25 cm2 applicators was performed as a function of height along applicator and of lateral distance from applicator body. Relative to central-axis ionization maximum in solid water, the maximum leakage in air observed with a cylindrical ion chamber with 1 cm solid water buildup cap at a lateral distance of 2 cm from the front and right sidewalls of applicators were 17% and 14%, respectively; these maxima were recorded for 18 MeV electron beams and applicator sizes of >or=20 x 20 cm2. In the patient plane, the applicator leakage gave rise to a broad peripheral dose off-axis distance peak that shifted closer to the field edge as the electron energy increases. The maximum peripheral dose from normally incident primary electron beams at a depth of 1 cm in a water phantom was observed to be equal to 5% of the central-axis dose maximum and as high as 9% for obliquely incident beams with angles of obliquity dose curves showed that the "practical range" of the leakage electrons in water varies from approximately 1.4 to 5.7 cm as the primary electron beam energy is raised from 6 to 18 MeV. Next, transmission measurements of leakage radiation through the shielding material Xenolite-NL showed a 4 mm thick sheet of this material is required to attenuate the leakage from 9 MeV beams by two-thirds, and that for every additional 3 MeV increase in the primary electron beam energy, an additional Xenolite-NL thickness of roughly 2 mm is needed to achieve the aforementioned attenuation level. Finally, attachment of a 1 mm thick sheet of lead to the outer surface of applicator sidewalls resulted in a reduction of the peripheral dose by up to 80% and 74% for 9 and 18MeV beams

  14. A comparison of adaptive iterative dose reduction 3D and filtered back projection in craniocervical CT angiography.

    PubMed

    Yu, S; Zhang, L; Zheng, J; Xu, Y; Chen, Y; Song, Z

    2017-01-01

    To compare the effects of exposure parameters on image quality and radiation dose for craniocervical computed tomography angiography (CTA) using adaptive iterative dose reduction in three dimensions (AIDR 3D) and filtered back projection (FBP) algorithms. One hundred and eighty patients were divided into three groups; group A (120 kV, 300 mA, FBP), group B (100 kV, automatic mA, AIDR 3D) and group C (80kV, automatic mA, AIDR 3D). Image quality and radiation dose were evaluated for each group. For both cervical and intracranial vessels, CT attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were higher in the AIDR 3D groups. The difference in mean vascular noise was also statistically significant (p<0.001), with group B having the lowest value at 16.5±3.2 HU and group C having the highest at 19.1±2.9 HU. FBP reconstruction resulted in lower image-quality scores for the common carotid artery. Parenchymal image-quality scores also varied significantly different between groups with group C partially failing to meet the minimum standards for diagnostic use. For the middle cerebral artery, image-quality scores were significantly better in group A, although images from groups B and C also satisfied clinical diagnostic requirements. The image quality of the internal carotid artery was the best in group B. Image-quality scores between groups were not significantly different for the carotid sinus. Radiation doses in the groups using AIDR 3D were >70% lower than in the FBP group. AIDR 3D (100 kV, automatic modulation) provides optimal image quality of vascular and parenchymal tissues at significantly lower radiation doses (mSV) than FBP in craniocervical CTA. For cases in which highly accurate parenchymal assessment is not required, the tube voltage can be lowered to 80 kV to further decrease radiation dose. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  15. Influence of the adaptive iterative dose reduction 3D algorithm on the detectability of low-contrast lesions and radiation dose repeatability in abdominal computed tomography: a phantom study.

    PubMed

    Yoon, Jeong Hee; Lee, Jeong Min; Hur, Bo Yun; Baek, Jeehyun; Shim, Hackjoon; Han, Joon Koo; Choi, Byung Ihn

    2015-08-01

    The purpose of the study is to evaluate the influence of the adaptive iterative dose reduction (AIDR 3D) algorithm on the detectability of low-contrast focal liver lesions (FLLs) and the radiation dose repeatability of automatic tube current modulation (ATCM) in abdominal CT scans using anthropomorphic phantoms. Three different sizes of anthropomorphic phantoms, each with 4 low-contrast FLLs, were scanned on a 320-channel CT scanner using the ATCM technique and AIDR 3D, at different radiation doses: full-dose, half-dose, and quarter-dose. Scans were repeated three times and reconstructed with filtered back projection (FBP) and AIDR 3D. Radiation dose repeatability was assessed using the intraclass correlation coefficient (ICC). Image noise, quality, and lesion conspicuity were assessed by four reviewers and the number of invisible FLLs was compared among different radiation doses and reconstruction methods. ICCs of radiation dose among the three CT scans were excellent in all phantoms (0.99). Image noise, quality, and lesion conspicuity in the half-dose group were comparable with full-dose FBP after applying AIDR 3D in all phantoms. In small phantoms, the half-dose group reconstructed with AIDR 3D showed similar sensitivity in visualizing low-contrast FLLs compared to full-dose FBP (P = 0.77-0.84). In medium and large phantoms, AIDR 3D reduced the number of missing low-contrast FLLs [3.1% (9/288), 11.5% (33/288), respectively], compared to FBP [10.4% (30/288), 21.9% (63/288), respectively] in the full-dose group. By applying AIDR 3D, half-dose CT scans may be achievable in small-sized patients without hampering diagnostic performance, while it may improve diagnostic performance in medium- and large-sized patients without increasing the radiation dose.

  16. Impact of dose reductions on efficacy outcome in heart transplant patients receiving enteric-coated mycophenolate sodium or mycophenolate mofetil at 12 months post-transplantation.

    PubMed

    Segovia, Javier; Gerosa, Gino; Almenar, Luis; Livi, Ugolino; Viganò, Mario; Arizón, Jose Maria; Yonan, Nizar; Di Salvo, Thomas G; Renlund, Dale G; Kobashigawa, Jon A

    2008-01-01

    Mycophenolic acid (MPA) dose reduction is associated with increased risk of rejection and graft loss in renal transplantation. This analysis investigated the impact of MPA dose changes with enteric-coated mycophenolate sodium (EC-MPS) or mycophenolate mofetil (MMF) in de novo heart transplant recipients. In a 12-month, single-blind trial, 154 patients (EC-MPS, 78; MMF, 76) were randomized to either EC-MPS (1080 mg bid) or MMF (1500 mg bid) in combination with cyclosporine and steroids. The primary efficacy variable was the incidence of treatment failure, comprising a composite of biopsy-proven (BPAR) and treated acute rejection, graft loss or death. Significantly fewer patients receiving EC-MPS required > or =2 dose reductions than patients on MMF (26.9% vs. 42.1% of patients, p = 0.048). Accordingly, the average daily dose of EC-MPS as a percentage of the recommended dose was significantly higher than for MMF (88.4% vs. 79.0%, p = 0.016). Among patients requiring > or =1 dose reduction, the incidence of treated BPAR grade > or =3A was significantly lower with EC-MPS compared with MMF (23.4% vs. 44.0%, p = 0.032). These data suggest that EC-MPS-treated heart transplant patients are less likely to require multiple dose reductions than those on MMF which may be associated with a significantly lower risk of treated BPAR > or =3A.

  17. Reduction of radiation dose and imaging costs in scoliosis radiography. Application of large-screen image intensifier photofluorography

    SciTech Connect

    Manninen, H.; Kiekara, O.; Soimakallio, S.; Vainio, J.

    1988-04-01

    Photofluorography using a large-field image intensifier (Siemens Optilux 57) was applied to scoliosis radiography and compared with a full-size rare-earth screen/film technique. When scoliosis radiography (PA-projection) was performed on 25 adolescent patients, the photofluorographs were found to be of comparable diagnostic quality with full-size films. A close correspondence between the imaging techniques was found in the Cobb angle measurements as well as in the grading of rotation with the pedicle method. The use of photofluorography results in a radiation dose reduction of about one-half and considerable savings in direct imaging costs and archive space. In our opinion the method is particularly well-suited for follow-up and screening evaluation of scoliosis, but in tall patients the image field size of 40 x 40 cm restricts its usefulness as initial examination.

  18. Multicentric survey on dose reduction/interruption of cancer drug therapy in 12.472 patients: indicators of suspected adverse reactions.

    PubMed

    Casadei Gardini, Andrea; Tenti, Elena; Masini, Carla; Nanni, Oriana; Scarpi, Emanuela; Valgiusti, Martina; Restuccia, Silvia; Gallani, Maria Laura; Palazzini, Simonetta; Bianchini, Erica; Menozzi, Silvia; Maugeri, Antonio; Amadori, Dino; Minguzzi, Martina; Frassineti, Giovanni Luca

    2016-06-28

    Antiblastic drugs have a high number of potential side-effects. Paradoxically, according to the National Network of Pharmacovigilance, the number of reported adverse reactions to these agents is proportionally lower than that registered for non antiblastic drugs. Critical phenomena such as treatment interruptions and significant dose reductions within the first two months of use may be indicators of adverse drug reactions. The aim of the present study was to increase our knowledge of pharmacovigilance to facilitate the actions taken to improve the risk-benefit profile of cancer drugs and, consequently, their safety. This retrospective observational survey was carried out on prescriptions from 1st January 2012 to 31st December 2012.Dose reductions of more than 10% during the first 90 days of therapy were considered as a surrogate indicator of an adverse reaction. Dose interruptions during the first 60 days of therapy were taken into consideration. Of the12,472 patients 1,248 underwent a dose reduction. The drugs that most often required a dose reduction were paclitaxel and oxaliplatin (17.4% and 17.3%, respectively), docetaxel (14.8%), carboplatin (15%), fluorouracil (10.7%) and, among oral medications, capecitabine (6.9%). Of the 1896 patients treated with the same drugs, 9.7% interrupted treatment. Patients required a lower dose reduction than that reported by other authors. Around 15% of cases underwent a 30% dose reduction within three months of starting therapy, indicating a possible adverse reaction. Constant monitoring of dose prescription and continuous training of medical and nursing staff are clearly needed to increase awareness of the importance of reporting adverse events.

  19. A Novel Pairwise Comparison-Based Method to Determine Radiation Dose Reduction Potentials of Iterative Reconstruction Algorithms, Exemplified Through Circle of Willis Computed Tomography Angiography.

    PubMed

    Ellmann, Stephan; Kammerer, Ferdinand; Brand, Michael; Allmendinger, Thomas; May, Matthias S; Uder, Michael; Lell, Michael M; Kramer, Manuel

    2016-05-01

    The aim of this study was to determine the dose reduction potential of iterative reconstruction (IR) algorithms in computed tomography angiography (CTA) of the circle of Willis using a novel method of evaluating the quality of radiation dose-reduced images. This study relied on ReconCT, a proprietary reconstruction software that allows simulating CT scans acquired with reduced radiation dose based on the raw data of true scans. To evaluate the performance of ReconCT in this regard, a phantom study was performed to compare the image noise of true and simulated scans within simulated vessels of a head phantom. That followed, 10 patients scheduled for CTA of the circle of Willis were scanned according to our institute's standard protocol (100 kV, 145 reference mAs). Subsequently, CTA images of these patients were reconstructed as either a full-dose weighted filtered back projection or with radiation dose reductions down to 10% of the full-dose level and Sinogram-Affirmed Iterative Reconstruction (SAFIRE) with either strength 3 or 5. Images were marked with arrows pointing on vessels of different sizes, and image pairs were presented to observers. Five readers assessed image quality with 2-alternative forced choice comparisons. In the phantom study, no significant differences were observed between the noise levels of simulated and true scans in filtered back projection, SAFIRE 3, and SAFIRE 5 reconstructions.The dose reduction potential for patient scans showed a strong dependence on IR strength as well as on the size of the vessel of interest. Thus, the potential radiation dose reductions ranged from 84.4% for the evaluation of great vessels reconstructed with SAFIRE 5 to 40.9% for the evaluation of small vessels reconstructed with SAFIRE 3. This study provides a novel image quality evaluation method based on 2-alternative forced choice comparisons. In CTA of the circle of Willis, higher IR strengths and greater vessel sizes allowed higher degrees of radiation dose

  20. A comparison of mantle versus involved-field radiotherapy for Hodgkin's lymphoma: reduction in normal tissue dose and second cancer risk

    PubMed Central

    Koh, Eng-Siew; Tran, Tu Huan; Heydarian, Mostafa; Sachs, Rainer K; Tsang, Richard W; Brenner, David J; Pintilie, Melania; Xu, Tony; Chung, June; Paul, Narinder; Hodgson, David C

    2007-01-01

    Background Hodgkin's lymphoma (HL) survivors who undergo radiotherapy experience increased risks of second cancers (SC) and cardiac sequelae. To reduce such risks, extended-field radiotherapy (RT) for HL has largely been replaced by involved field radiotherapy (IFRT). While it has generally been assumed that IFRT will reduce SC risks, there are few data that quantify the reduction in dose to normal tissues associated with modern RT practice for patients with mediastinal HL, and no estimates of the expected reduction in SC risk. Methods Organ-specific dose-volume histograms (DVH) were generated for 41 patients receiving 35 Gy mantle RT, 35 Gy IFRT, or 20 Gy IFRT, and integrated organ mean doses were compared for the three protocols. Organ-specific SC risk estimates were estimated using a dosimetric risk-modeling approach, analyzing DVH data with quantitative, mechanistic models of radiation-induced cancer. Results Dose reductions resulted in corresponding reductions in predicted excess relative risks (ERR) for SC induction. Moving from 35 Gy mantle RT to 35 Gy IFRT reduces predicted ERR for female breast and lung cancer by approximately 65%, and for male lung cancer by approximately 35%; moving from 35 Gy IFRT to 20 Gy IFRT reduces predicted ERRs approximately 40% more. The median reduction in integral dose to the whole heart with the transition to 35 Gy IFRT was 35%, with a smaller (2%) reduction in dose to proximal coronary arteries. There was no significant reduction in thyroid dose. Conclusion The significant decreases estimated for radiation-induced SC risks associated with modern IFRT provide strong support for the use of IFRT to reduce the late effects of treatment. The approach employed here can provide new insight into the risks associated with contemporary IFRT for HL, and may facilitate the counseling of patients regarding the risks associated with this treatment. PMID:17362522

  1. Adaptive Iterative Dose Reduction Using Three Dimensional Processing (AIDR3D) Improves Chest CT Image Quality and Reduces Radiation Exposure

    PubMed Central

    Yamashiro, Tsuneo; Miyara, Tetsuhiro; Honda, Osamu; Kamiya, Hisashi; Murata, Kiyoshi; Ohno, Yoshiharu; Tomiyama, Noriyuki; Moriya, Hiroshi; Koyama, Mitsuhiro; Noma, Satoshi; Kamiya, Ayano; Tanaka, Yuko; Murayama, Sadayuki

    2014-01-01

    Objective To assess the advantages of Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D) for image quality improvement and dose reduction for chest computed tomography (CT). Methods Institutional Review Boards approved this study and informed consent was obtained. Eighty-eight subjects underwent chest CT at five institutions using identical scanners and protocols. During a single visit, each subject was scanned using different tube currents: 240, 120, and 60 mA. Scan data were converted to images using AIDR3D and a conventional reconstruction mode (without AIDR3D). Using a 5-point scale from 1 (non-diagnostic) to 5 (excellent), three blinded observers independently evaluated image quality for three lung zones, four patterns of lung disease (nodule/mass, emphysema, bronchiolitis, and diffuse lung disease), and three mediastinal measurements (small structure visibility, streak artifacts, and shoulder artifacts). Differences in these scores were assessed by Scheffe's test. Results At each tube current, scans using AIDR3D had higher scores than those without AIDR3D, which were significant for lung zones (p<0.0001) and all mediastinal measurements (p<0.01). For lung diseases, significant improvements with AIDR3D were frequently observed at 120 and 60 mA. Scans with AIDR3D at 120 mA had significantly higher scores than those without AIDR3D at 240 mA for lung zones and mediastinal streak artifacts (p<0.0001), and slightly higher or equal scores for all other measurements. Scans with AIDR3D at 60 mA were also judged superior or equivalent to those without AIDR3D at 120 mA. Conclusion For chest CT, AIDR3D provides better image quality and can reduce radiation exposure by 50%. PMID:25153797

  2. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA

    SciTech Connect

    Khan, T.A.; Vulin, D.S.; Lane, S.G.; Baum, J.W. )

    1991-10-01

    In the continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants, the ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA. This is the sixth report in that series. The abstracts in this bibliography were selected from proceedings of technical meetings and conferences, journals, research reports, and searches of information databases of the US Department of Energy. The subject material of these abstracts relates to radiation protection and dose reduction, and ranges from the use of robotics, to operational health physics, to water chemistry. Also included is material on the design, planning, and management of nuclear power stations, as well as on decommissioning and safe storage efforts. This report contains 266 abstracts along with subject and author indices. The author index is exclusively for this volume. The subject index contains headings for this volume in bold face, as well as reference to previous volumes. All information in this and previous volumes of the series is also available through our on-line information system called ACE (ALARA Center Exchange). ACE is accessible through fax machines or personal computers interfaced with modems. The bibliography database and other databases are kept current with new abstracts, information on research projects, and recent news of international events related to ALARA at nuclear power plants. Access to the system is provided freely to the ALARA community. For password certification, manuals, and other information about our system, please contact the ALARA CENTER, Building 703M, Brookhaven National Laboratory, Upton, NY 11973, or call (516) 282-3228.

  3. Measuring radiation dose in computed tomography using elliptic phantom and free-in-air, and evaluating iterative metal artifact reduction algorithm

    NASA Astrophysics Data System (ADS)

    Morgan, Ashraf

    The need for an accurate and reliable way for measuring patient dose in multi-row detector computed tomography (MDCT) has increased significantly. This research was focusing on the possibility of measuring CT dose in air to estimate Computed Tomography Dose Index (CTDI) for routine quality control purposes. New elliptic CTDI phantom that better represent human geometry was manufactured for investigating the effect of the subject shape on measured CTDI. Monte Carlo simulation was utilized in order to determine the dose distribution in comparison to the traditional cylindrical CTDI phantom. This research also investigated the effect of Siemens health care newly developed iMAR (iterative metal artifact reduction) algorithm, arthroplasty phantom was designed and manufactured that purpose. The design of new phantoms was part of the research as they mimic the human geometry more than the existing CTDI phantom. The standard CTDI phantom is a right cylinder that does not adequately represent the geometry of the majority of the patient population. Any dose reduction algorithm that is used during patient scan will not be utilized when scanning the CTDI phantom, so a better-designed phantom will allow the use of dose reduction algorithms when measuring dose, which leads to better dose estimation and/or better understanding of dose delivery. Doses from a standard CTDI phantom and the newly-designed phantoms were compared to doses measured in air. Iterative reconstruction is a promising technique in MDCT dose reduction and artifacts correction. Iterative reconstruction algorithms have been developed to address specific imaging tasks as is the case with Iterative Metal Artifact Reduction or iMAR which was developed by Siemens and is to be in use with the companys future computed tomography platform. The goal of iMAR is to reduce metal artifact when imaging patients with metal implants and recover CT number of tissues adjacent to the implant. This research evaluated i

  4. Effect of the reduction of skin contamination on the internal dose of creosote workers exposed to polycyclic aromatic hydrocarbons.

    PubMed

    Van Rooij, J G; Van Lieshout, E M; Bodelier-Bade, M M; Jongeneelen, F J

    1993-06-01

    Ten creosote-exposed workers of a wood impregnation plant participated in this study, which took place in two consecutive weeks on a Monday, after a weekend off. On one of the two days each worker wore Tyvek coveralls underneath his normal workclothes. Dermal contamination measurements (pyrene on exposure pads) and biological monitoring (urinary 1-OH-pyrene) were performed to measure the reduction of both the skin contamination and the internal dose. The total pyrene skin contamination of workers not wearing coveralls ranged between 47 and 1510 micrograms.d-1 (0.2-7.5 mumol.d-1). On the average, the coveralls reduced the pyrene contamination on the workers' skin by about 35 (SD 63)%. The excreted amount of 1-OH-pyrene in urine decreased significantly from 6.6 to 3.2 micrograms (30.2 to 14.7 nmol). Multiple regression analysis showed that skin contamination by polycyclic aromatic hydrocarbons is the main determinant of the internal exposure dose of creosote workers.

  5. Automated Tube Voltage Selection for Radiation Dose Reduction in CT Angiography Using Different Contrast Media Concentrations and a Constant Iodine Delivery Rate.

    PubMed

    Kok, Madeleine; Mihl, Casper; Seehofnerová, Anna; Turek, Jakub; Jost, Gregor; Pietsch, Hubertus; Haberland, Ulrike; Wildberger, Joachim E; Das, Marco

    2015-12-01

    The purpose of this study was to systematically investigate radiation dose reduction using automated tube voltage selection during CT angiography (CTA) and to evaluate the impact of contrast medium (CM) injection protocols on dose reduction. A circulation phantom containing the thoracic and abdominal vasculature was used. Four different concentrations of CM (iopromide 300 and 370 mg I/mL and iomeprol 350 and 400 mg I/mL) were administered while maintaining an identical iodine delivery rate (1.8 g I/s) and total iodine load (20.0 g). Three different scanning protocols for CTA of the thoracoabdominal aorta were used: protocol A, no dose modulation; protocol B, automated tube current modulation (CARE Dose4D); and protocol C, automated tube voltage selection (CARE kV). The dose-length product was recorded to calculate the effective dose. Attenuation values (in Hounsfield units), image noise levels, and signal-to-noise ratios (SNRs) in six predefined intravascular sites (three thoracic and three abdominal) were measured by two readers. All values were analyzed using the Kruskal-Wallis test and two-way ANOVA. There was a significant reduction in the effective dose (in millisieverts) for protocols B (mean ± SD, 2.03 ± 0.1 mSv) and C (1.00 ± 0.0 mSv) compared with protocol A (4.34 ± 0.0 mSv). The dose was reduced by 53% for protocol B and by 77% for protocol C. No significant differences were found in the effective dose among the different CM injection protocols within the scanning protocols; all p values were > 0.05. The attenuation values and SNRs were comparable among all the different CM injection protocols; all p values were > 0.05. A large radiation dose reduction (77%) can be achieved using automated tube voltage selection independent of the CM injection protocol.

  6. Effects of Arbutin on Radiation-Induced Micronuclei in Mice Bone Marrow Cells and Its Definite Dose Reduction Factor.

    PubMed

    Nadi, Saba; Monfared, Ali Shabestani; Mozdarani, Hossein; Mahmodzade, Aziz; Pouramir, Mahdi

    2016-05-01

    Interactions of free radicals from ionizing radiation with DNA can induce DNA damage and lead to mutagenesis and carsinogenesis. With respect to radiation damage to human, it is important to protect humans from side effects induced by ionizing radiation. In the present study, the effects of arbutin were investigated by using the micronucleus test for anti-clastogenic activity, to calculate the ratio of polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte (PCE/PCE+NCE) in order to show cell proliferation activity. Arbutin (50, 100, and 200 mg/kg) was intraperitoneally (ip)administered to NMRI mice two hours before gamma radiation at 2 and 4 gray (Gy). The frequency of micronuclei in 1000 PCEs (MnPCEs) and the ratio of PCE/PCE+NCE were calculated for each sample. Data were statistically evaluated using one-way ANOVA, Tukey HSD test, and t-test. The findings indicated that gamma radiation at 2 and 4 Gy extremely increased the frequencies of MnPCE (P<0.001) while reducing PCE/PCE+NCE (P<0.001) compared to the control group. All three doses of arbutin before irradiation significantly reduced the frequencies of MnPCEs and increased the ratio of PCE/PCE+NCE in mice bone marrow compared to the non-drug-treated irradiated control (P<0.001). All three doses of arbutin had no toxicity effect on bone marrow cells. The calculated dose reduction factor (DRF) showed DRF=1.93 for 2Gy and DRF=2.22 for 4 Gy. Our results demonstrated that arbutin gives significant protection to rat bone against the clastogenic and cytotoxic effects of gamma irradiation.

  7. Effects of Arbutin on Radiation-Induced Micronuclei in Mice Bone Marrow Cells and Its Definite Dose Reduction Factor

    PubMed Central

    Nadi, Saba; Monfared, Ali Shabestani; Mozdarani, Hossein; Mahmodzade, Aziz; Pouramir, Mahdi

    2016-01-01

    Background: Interactions of free radicals from ionizing radiation with DNA can induce DNA damage and lead to mutagenesis and carsinogenesis. With respect to radiation damage to human, it is important to protect humans from side effects induced by ionizing radiation. In the present study, the effects of arbutin were investigated by using the micronucleus test for anti-clastogenic activity, to calculate the ratio of polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte (PCE/PCE+NCE) in order to show cell proliferation activity. Methods: Arbutin (50, 100, and 200 mg/kg) was intraperitoneally (ip)administered to NMRI mice two hours before gamma radiation at 2 and 4 gray (Gy). The frequency of micronuclei in 1000 PCEs (MnPCEs) and the ratio of PCE/PCE+NCE were calculated for each sample. Data were statistically evaluated using one-way ANOVA, Tukey HSD test, and t-test. Results: The findings indicated that gamma radiation at 2 and 4 Gy extremely increased the frequencies of MnPCE (P<0.001) while reducing PCE/PCE+NCE (P<0.001) compared to the control group. All three doses of arbutin before irradiation significantly reduced the frequencies of MnPCEs and increased the ratio of PCE/PCE+NCE in mice bone marrow compared to the non-drug-treated irradiated control (P<0.001). All three doses of arbutin had no toxicity effect on bone marrow cells. The calculated dose reduction factor (DRF) showed DRF=1.93 for 2Gy and DRF=2.22 for 4 Gy. Conclusion: Our results demonstrated that arbutin gives significant protection to rat bone against the clastogenic and cytotoxic effects of gamma irradiation. PMID:27217601

  8. Dose reduction by moving a region of interest (ROI) beam attenuator to follow a moving object of interest

    NASA Astrophysics Data System (ADS)

    Panse, Ashish S.; Swetadri Vasan, S. N.; Jain, A.; Bednarek, D. R.; Rudin, S.

    2012-03-01

    Region-of-interest (ROI) fluoroscopy takes advantage of the fact that most neurovascular interventional activity is performed in only a small portion of an x-ray imaging field of view (FOV). The ROI beam filter is an attenuating material that reduces patient dose in the area peripheral to the object of interest. This project explores a method of moving the beam-attenuator aperture with the object of interest such that it always remains in the ROI. In this study, the ROI attenuator, which reduces the dose by 80% in the peripheral region, is mounted on a linear stage placed near the xray tube. Fluoroscopy is performed using the Microangiographic Fluoroscope (MAF) which is a high-resolution, CCD-based x-ray detector. A stainless-steel stent is selected as the object of interest, and is moved across the FOV and localized using an object-detection algorithm available in the IMAQ Vision package of LabVIEW. The ROI is moved to follow the stent motion. The pixel intensities are equalized in both FOV regions and an adaptive temporal filter dependent on the motion of the object of interest is implemented inside the ROI. With a temporal filter weight of 5% for the current image in the peripheral region, the SNR measured is 47.8. The weights inside the ROI vary between 10% and 33% with a measured SNR of 57.9 and 35.3 when the object is stationary and moving, respectively. This method allows patient dose reduction as well as maintenance of superior image quality in the ROI while tracking the object.

  9. [Usefulness of high helical pitch acquisition for reduction of patient radiation dose in cardiac multidetector computed tomography].

    PubMed

    Sano, Tomonari; Matsutani, Hideyuki; Kondo, Takeshi; Sekine, Takako; Arai, Takehiro; Morita, Hitomi; Takase, Shinichi

    2009-07-20

    Helical pitch (HP) usually has been decided automatically by the software (Heart Navi) included in the MDCT machine (Aquilion 64) depending on gantry rotation speed (r) and heart rate (HR). To reduce radiation dose, 255 consecutive patients with low HR (< or =60 bpm) and without arrhythmia underwent cardiac MDCT using high HP. We had already reported that the relationship among r, HP, and the maximum data acquisition time interval (Tmax) does not create the data deficit in arrhythmia. It was represented as Tmax= (69.88/HP-0.64) r; (equation 1). From equation 1, HP=69.88 r/ (Tmax+0.64 r); (equation 2) was derived. We measured the maximum R-R interval (R-Rmax) on ECG before MDCT acquisition, and R-Rmaxx1.1 was calculated as Tmax in consideration of R-Rmax prolongation during MDCT acquisition. The HP of high HP acquisition was calculated from equation 2. In HR< or =50 bpm, Heart Navi determined r: 0.35 sec/rot and HP: 9.8, and in 51 bpm< or =HR< or =66 bpm, r: 0.35 sec/rot and HP: 11.2. HP of the high HP (16.4+/-1.2) was significantly (p<0.0001) higher than that of Heart Navi HP (10.9+/-0.6). The scanning time (6.5+/-0.6 sec) of high HP was significantly (p<0.0001) shorter than that of Heart Navi (9.0+/-0.8 sec), and the dose length product of high HP (675+/-185 mGy x cm) was significantly (p<0.0001) lower than that of Heart Navi (923+/-252 mGy x cm). The high HP could produce fine images in 251/255 patients. In conclusion, the high HP acquisition is useful for reduction of radiation dose and scanning time.

  10. Dose reduction by moving a region of interest (ROI) beam attenuator to follow a moving object of interest.

    PubMed

    Panse, Ashish S; Swetadri Vasan, S N; Jain, A; Bednarek, D R; Rudin, S

    2012-01-01

    Region-of-interest (ROI) fluoroscopy takes advantage of the fact that most neurovascular interventional activity is performed in only a small portion of an x-ray imaging field of view (FOV). The ROI beam filter is an attenuating material that reduces patient dose in the area peripheral to the object of interest. This project explores a method of moving the beam-attenuator aperture with the object of interest such that it always remains in the ROI. In this study, the ROI attenuator, which reduces the dose by 80% in the peripheral region, is mounted on a linear stage placed near the x-ray tube. Fluoroscopy is performed using the Microangiographic Fluoroscope (MAF) which is a high-resolution, CCD-based x-ray detector. A stainless-steel stent is selected as the object of interest, and is moved across the FOV and localized using an object-detection algorithm available in the IMAQ Vision package of LabVIEW. The ROI is moved to follow the stent motion. The pixel intensities are equalized in both FOV regions and an adaptive temporal filter dependent on the motion of the object of interest is implemented inside the ROI. With a temporal filter weight of 5% for the current image in the peripheral region, the SNR measured is 47.8. The weights inside the ROI vary between 10% and 33% with a measured SNR of 57.9 and 35.3 when the object is stationary and moving, respectively. This method allows patient dose reduction as well as maintenance of superior image quality in the ROI while tracking the object.

  11. Dose reduction by moving a region of interest (ROI) beam attenuator to follow a moving object of interest

    PubMed Central

    Panse, Ashish S.; Swetadri Vasan, S. N.; Jain, A.; Bednarek, D. R.; Rudin, S.

    2012-01-01

    Region-of-interest (ROI) fluoroscopy takes advantage of the fact that most neurovascular interventional activity is performed in only a small portion of an x-ray imaging field of view (FOV). The ROI beam filter is an attenuating material that reduces patient dose in the area peripheral to the object of interest. This project explores a method of moving the beam-attenuator aperture with the object of interest such that it always remains in the ROI. In this study, the ROI attenuator, which reduces the dose by 80% in the peripheral region, is mounted on a linear stage placed near the x-ray tube. Fluoroscopy is performed using the Microangiographic Fluoroscope (MAF) which is a high-resolution, CCD-based x-ray detector. A stainless-steel stent is selected as the object of interest, and is moved across the FOV and localized using an object-detection algorithm available in the IMAQ Vision package of LabVIEW. The ROI is moved to follow the stent motion. The pixel intensities are equalized in both FOV regions and an adaptive temporal filter dependent on the motion of the object of interest is implemented inside the ROI. With a temporal filter weight of 5% for the current image in the peripheral region, the SNR measured is 47.8. The weights inside the ROI vary between 10% and 33% with a measured SNR of 57.9 and 35.3 when the object is stationary and moving, respectively. This method allows patient dose reduction as well as maintenance of superior image quality in the ROI while tracking the object. PMID:22866212

  12. Feedback on the use of the MX6 Mox Fuel transport cask: reduction of the dose uptake during operations

    SciTech Connect

    Blachet, L.; Lallemant, Th.

    2007-07-01

    In the framework of the quality, safety and environment policy of AREVA, TN International has implemented a global management system according to ISO 9001, OHSAS 18001 and ISO 14001 requirements with certification obtained from third part organization (1). The design of the MX6 cask is an example of the implementation of this system in order to guarantee safety and the health of everyone involved and the protection of the environment. The MX6 design has allowed ALARA dose rates for the workers during all the phases of use of the cask, to be significantly reduced compared to previous design. The MX6 cask was developed by TN International for the transport of either BWR or PWR fresh MOX fuel assemblies. Replacing the previous SIEMENS type III and SIEMENS BWR packaging, the MX6 has been firstly used in the German Nuclear Power Plants. Complying with the TS-R-1 (IAEA 1996) regulations, the MX6 cask is based on innovative solutions implemented at each step of the design and the manufacturing. Its design includes an efficient neutron shielding for high Plutonium content and an easy use content restraining system. The large payload of the MX6 cask, 6 PWR MOX fuel assemblies or 16 BWR MOX fuel assemblies, minimizes the doses uptake during its unloading at the NPP. Moreover, new sequences of loading and unloading operations were proposed for testing and implementation in each Nuclear Facility. Concurrently, total dose uptakes by the operators were assessed in order to prove the efficiency of the packaging and the proposed sequences. In this paper, the main contributors to the transports to Germany with the MX6 cask will present their involvement and feedback for the reduction of the dose uptakes by the operators during the loading and unloading operations. Presently in use at GUNDREMMINGEN and ISAR Nuclear Power Plants (NPPs), the MX6 cask use will be extended to other German and Swiss NPPs from 2006 onwards. (1) AFAQ-AFNOR Certification for ISO 9001, OHSAS 18001 and ISO

  13. Dose reduction and image quality assessment in 64-detector row computed tomography of the coronary arteries using an automatic exposure control system.

    PubMed

    Francone, Marco; Di Castro, Elisabetta; Napoli, Alessandro; Bolzan, Chiara; Carbone, Iacopo; Bertoletti, Linda; Iuliano, Luigi; Catalano, Carlo; Passariello, Roberto

    2008-01-01

    To evaluate dose reduction and image quality in coronary 64-slice multidetector computed tomography using an automatic exposure control system (AECs). A total of 101 patients were divided into 4 groups. Tube current was 600 and 800 mAs in groups A and B and adapted at 600 and 800 quality-reference mAs using an AECs in groups C and D. Effective dose and organ-equivalent dose were evaluated. Image noise was quantified as standard deviation of air-space attenuation. Two observers assessed technical adequacy and image quality using a 4-point scale. Effective dose ranged from 8.6 mSv (group C) to 15 mSv (group B) with significant dose reduction for examinations performed at 600 mAs (21.7%) and 800 mAs (29.4%). Contribution of organ-equivalent doses showed higher exposure for lungs (42%) and breast (22%). Noise was significantly higher in groups studied with AECs. Larger coronary segments resulted in higher image quality scores without differences between groups. Automatic exposure control systems provides images of diagnostic quality with substantial dose reduction.

  14. Evaluation of a noise reduction imaging technology in iliac digital subtraction angiography: noninferior clinical image quality with lower patient and scatter dose.

    PubMed

    van Strijen, Marco J; Grünhagen, Thijs; Mauti, Maria; Zähringer, Markus; Gaines, Peter A; Robinson, Graham J; Railton, Nicholas J; van Overhagen, Hans; Habraken, Jan; van Leersum, Marc

    2015-05-01

    To determine whether equivalent-quality images can be obtained from digital subtraction angiography (DSA) of the iliac artery after implementation of a novel imaging technology that reduces patient and scatter x-ray dose. Imaging using two randomly ordered DSA runs was performed in 51 adults scheduled for iliac artery angiography or intervention or both. One DSA run used standard acquisition chain and image processing algorithms (referred to as " reference DSA"), and the other DSA run used dose-reduction and real-time advanced image noise reduction technology (referred to as "study DSA"). The quality of each pair of runs, consecutively performed without changes in working projection or injection parameters, was independently rated by five radiologists blinded to the imaging technology used. Patient radiation dose was evaluated using air kerma and dose area product, and scatter dose was evaluated using three dosimeters (DoseAware, Philips Healthcare, Best, The Netherlands), located at fixed positions. Comparable image pairs were available in 48 patients. There were 44 patients undergoing treatment involving the common (n = 33) or external (n = 29) iliac arteries. Study DSA images were rated as equal to or better than reference DSA images for 96% of comparisons, with an average overall agreement among raters of 0.93 (95% confidence interval, 0.65-0.96). Mean patient radiation dose (n = 48) and scatter dose rate for the three dosimeters (n = 50) was 83% ± 5 and 69% ± 10 lower, respectively, using the study technology (P < .001). Iliac artery DSA performed using a dose-reduction and real-time advanced image noise reduction technology results in image quality that is noninferior to conventional DSA but with significantly lower patient and scatter radiation exposure (P < .001). Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

  15. Radiation dose reduction to the breast in thoracic CT: Comparison of bismuth shielding, organ-based tube current modulation, and use of a globally decreased tube current

    SciTech Connect

    Wang Jia; Duan Xinhui; Christner, Jodie A.; Leng Shuai; Yu Lifeng; McCollough, Cynthia H.

    2011-11-15

    Purpose: The purpose of this work was to evaluate dose performance and image quality in thoracic CT using three techniques to reduce dose to the breast: bismuth shielding, organ-based tube current modulation (TCM) and global tube current reduction. Methods: Semi-anthropomorphic thorax phantoms of four different sizes (15, 30, 35, and 40 cm lateral width) were used for dose measurement and image quality assessment. Four scans were performed on each phantom using 100 or 120 kV with a clinical CT scanner: (1) reference scan; (2) scan with bismuth breast shield of an appropriate thickness; (3) scan with organ-based TCM; and (4) scan with a global reduction in tube current chosen to match the dose reduction from bismuth shielding. Dose to the breast was measured with an ion chamber on the surface of the phantom. Image quality was evaluated by measuring the mean and standard deviation of CT numbers within the lung and heart regions. Results: Compared to the reference scan, dose to the breast region was decreased by about 21% for the 15-cm phantom with a pediatric (2-ply) shield and by about 37% for the 30, 35, and 40-cm phantoms with adult (4-ply) shields. Organ-based TCM decreased the dose by 12% for the 15-cm phantom, and 34-39% for the 30, 35, and 40-cm phantoms. Global lowering of the tube current reduced breast dose by 23% for the 15-cm phantom and 39% for the 30, 35, and 40-cm phantoms. In phantoms of all four sizes, image noise was increased in both the lung and heart regions with bismuth shielding. No significant increase in noise was observed with organ-based TCM. Decreasing tube current globally led to similar noise increases as bismuth shielding. Streak and beam hardening artifacts, and a resulting artifactual increase in CT numbers, were observed for scans with bismuth shields, but not for organ-based TCM or global tube current reduction. Conclusions: Organ-based TCM produces dose reduction to the breast similar to that achieved with bismuth shielding for

  16. Doses of rosuvastatin, atorvastatin and simvastatin that induce equal reductions in LDL-C and non-HDL-C: Results from the VOYAGER meta-analysis.

    PubMed

    Karlson, Björn W; Palmer, Michael K; Nicholls, Stephen J; Lundman, Pia; Barter, Philip J

    2016-05-01

    Achieving the greatest reduction in atherogenic lipoproteins requires the optimum dose and potency of statin. Using data from the VOYAGER meta-analysis, we determined doses of rosuvastatin, atorvastatin and simvastatin that induce equal reductions in low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (non-HDL-C). Least squares mean percentage change in LDL-C and non-HDL-C was calculated using 38,052 patient exposures to rosuvastatin 5-40 mg, atorvastatin 10-80 mg and simvastatin 10-80 mg. Equipotent doses were estimated by linear interpolation between actual adjacent doses. Rosuvastatin 5 mg reduced LDL-C by 39% and non-HDL-C by 35%. Equivalent reductions in LDL-C required atorvastatin 15 mg or simvastatin 39 mg. Equivalent reductions in non-HDL-C required atorvastatin 14 mg or simvastatin 42 mg. Rosuvastatin 10 mg reduced LDL-C by 44% and non-HDL-C by 40%. Equivalent reductions in LDL-C required atorvastatin 29 mg or simvastatin 72 mg. Equivalent reductions in non-HDL-C required atorvastatin 27 mg or simvastatin 77 mg. Rosuvastatin 20 mg reduced LDL-C by 50% and non-HDL-C by 45%. Equivalent reductions in LDL-C and non-HDL-C required atorvastatin 70 mg and atorvastatin 62 mg, respectively, and were not achieved with the maximum 80 mg dose of simvastatin. Rosuvastatin 40 mg reduced LDL-C by 55% and non-HDL-C by 50%. Comparable reductions were not achieved with the maximum 80 mg doses of atorvastatin or simvastatin. Regarding reductions in LDL-C and non-HDL-C, each rosuvastatin dose is equivalent to doses 3-3.5 times higher for atorvastatin and 7-8 times higher for simvastatin. © The European Society of Cardiology 2015.

  17. Reduction of neonatal tetanus by mass immunization of non-pregnant women: duration of protection provided by one or two doses of aluminium-adsorbed tetanus toxoid*

    PubMed Central

    Black, R. E.; Huber, D. H.; Curlin, G. T.

    1980-01-01

    Immunization of non-pregnant women in rural Bangladesh with two doses of aluminium-adsorbed tetanus-diphtheria toxoids reduced neonatal mortality by one-third during a period of 9-32 months after vaccination. The reduction in mortality rate was attributable almost entirely to a 75% lower mortality rate among 4-14-day-old infants, when tetanus was the predominant cause of death. In the period up to 20 months following vaccination, the reduction in deaths among 4-14-day-old infants after a single dose of tetanus-diptheria toxoids was about the same as that after two doses. However, beyond 20 months a single dose did not appear to provide protection. PMID:6971190

  18. High interindividual variability in dose-dependent reduction in speed of movement after exposing C. elegans to shock waves

    PubMed Central

    Angstman, Nicholas B.; Kiessling, Maren C.; Frank, Hans-Georg; Schmitz, Christoph

    2015-01-01

    In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI. PMID:25705183

  19. Little Evidence for Usefulness of Biomarkers for Predicting Successful Dose Reduction or Discontinuation of a Biologic Agent in Rheumatoid Arthritis: A Systematic Review

    PubMed Central

    van den Ende, Cornelia H.; Beeren, Fenna M. M.; Been, Evelien M. J.; van den Hoogen, Frank H. J.; den Broeder, Alfons A.

    2017-01-01

    Objective To systematically review studies addressing prediction of successful dose reduction or discontinuation of a biologic agent in rheumatoid arthritis (RA). Methods PubMed, Embase, and Cochrane Library databases were searched for studies that examined the predictive value of biomarkers for successful dose reduction or discontinuation of a biologic agent in RA. Two reviewers independently selected studies, and extracted data and assessed the risk of bias. A biomarker was classified as a “potential predictor” if the univariate association was either strong (odds ratio or hazard ratio >2.0 or <0.5) or statistically significant. For biomarkers that were studied multiple times, qualitative best‐evidence synthesis was performed separately for the prediction of successful dose reduction and discontinuation. Biomarkers that were defined in ≥75% of the studies as potential predictors were regarded as “predictor” for the purposes of our study. Results Of 3,029 nonduplicate articles initially searched, 16 articles regarding 15 cohorts were included in the present study. Overall, 17 biomarkers were studied multiple times for the prediction of successful dose reduction, and 33 for the prediction of successful discontinuation of a biologic agent. Three predictors were identified: higher adalimumab trough level for successful dose reduction and lower Sharp/van der Heijde erosion score and shorter symptom duration at the start of a biologic agent for successful discontinuation. Conclusion The predictive value of a wide variety of biomarkers for successful dose reduction or discontinuation of biologic treatment in RA has been investigated. We identified only 3 biomarkers as predictors, in just 2 studies. The strength of the evidence is limited by the low quality of the included studies and the likelihood of reporting bias and multiple testing. PMID:27696778

  20. SU-E-T-329: Dosimetric Impact of Implementing Metal Artifact Reduction Methods and Metal Energy Deposition Kernels for Photon Dose Calculations

    SciTech Connect

    Huang, J; Followill, D; Howell, R; Liu, X; Mirkovic, D; Stingo, F; Kry, S

    2015-06-15

    Purpose: To investigate two strategies for reducing dose calculation errors near metal implants: use of CT metal artifact reduction methods and implementation of metal-based energy deposition kernels in the convolution/superposition (C/S) method. Methods: Radiochromic film was used to measure the dose upstream and downstream of titanium and Cerrobend implants. To assess the dosimetric impact of metal artifact reduction methods, dose calculations were performed using baseline, uncorrected images and metal artifact reduction Methods: Philips O-MAR, GE’s monochromatic gemstone spectral imaging (GSI) using dual-energy CT, and GSI imaging with metal artifact reduction software applied (MARs).To assess the impact of metal kernels, titanium and silver kernels were implemented into a commercial collapsed cone C/S algorithm. Results: The CT artifact reduction methods were more successful for titanium than Cerrobend. Interestingly, for beams traversing the metal implant, we found that errors in the dimensions of the metal in the CT images were more important for dose calculation accuracy than reduction of imaging artifacts. The MARs algorithm caused a distortion in the shape of the titanium implant that substantially worsened the calculation accuracy. In comparison to water kernel dose calculations, metal kernels resulted in better modeling of the increased backscatter dose at the upstream interface but decreased accuracy directly downstream of the metal. We also found that the success of metal kernels was dependent on dose grid size, with smaller calculation voxels giving better accuracy. Conclusion: Our study yielded mixed results, with neither the metal artifact reduction methods nor the metal kernels being globally effective at improving dose calculation accuracy. However, some successes were observed. The MARs algorithm decreased errors downstream of Cerrobend by a factor of two, and metal kernels resulted in more accurate backscatter dose upstream of metals. Thus

  1. Infliximab Dose Reduction Sustains the Clinical Treatment Effect in Active HLAB27 Positive Ankylosing Spondylitis: A Two-Year Pilot Study

    PubMed Central

    Mörck, Boel; Bremell, Tomas; Forsblad-d'Elia, Helena

    2013-01-01

    The rationale of the study was to evaluate the efficacy of infliximab (IFX) treatment in patients with ankylosing spondylitis (AS) and to determine whether IFX dose reduction and interval extension sustains the treatment effect. Nineteen patients were included and treated with IFX 5 mg/kg every 6 weeks for 56 weeks. All patients concomitantly received MTX with median dose 7.5 mg/weekly. During the second year, the IFX dose was reduced to 3 mg/kg every 8 weeks. Eighteen patients completed the 1-year and 15 patients the 2-year trial. The ≥50% improvement at week 16 from baseline of BASDAI was achieved in 16/19 (84%) patients. Significant reductions in BASDAI, BASFI, and BASMI scores, decrease in ESR and CRP, and improvement in SF-36 were observed at weeks 16 and 56. The MRI-defined inflammatory changes in the sacroiliac joints disappeared in 10/15 patients (67%) already at 16 weeks. IFX treatment effect was sustained throughout the second year after IFX dose reduction and interval extension. We conclude that IFX treatment is effective in well-established active AS and a dose reduction sustains the treatment effect. These observations are of clinical importance and open the opportunity to reduce the drug costs. This trial is registered with ClinicalTrials.gov NCT01850121. PMID:24089587

  2. Dose reduction and its influence on diagnostic accuracy and radiation risk in digital mammography: an observer performance study using an anthropomorphic breast phantom

    PubMed Central

    Svahn, Tony; Hemdal, Bengt; Ruschin, Mark; Chakraborty, Dev P; Andersson, Ingvar; Tingberg, Anders; Mattsson, Sören

    2008-01-01

    This study aimed to investigate the effect of dose reduction on diagnostic accuracy and radiation risk in digital mammography. Simulated masses and microcalcifications were positioned in an anthropomorphic breast phantom. Thirty digital images, 14 with lesions, 16 without, were acquired of the phantom using a Mammomat Novation (Siemens, Erlangen, Germany) at each of three dose levels. These corresponded to 100%, 50% and 30% of the normally used average glandular dose (AGD; 1.3 mGy for a standard breast). Eight observers interpreted the 90 unprocessed images in a free-response study and the data was analyzed with the jackknife free-response receiver operating characteristic (JAFROC) method. Observer performance was assessed using the JAFROC figure of merit (FOM). The benefit of radiation risk reduction was estimated based on several risk models. There was no statistically significant difference in performance, as described by the FOM, between the 100% and the 50% dose levels. However, the FOMs for both the 100% and the 50% dose were significantly different from the corresponding quantity for the 30% dose level (F-statistic = 4.95, p-value = 0.01). A dose reduction of 50% would result in 3-9 fewer breast cancer fatalities per 100,000 women undergoing annual screening from the age of 40 to 49 years. The results of the study indicate a possibility of reducing the dose to the breast to half of the dose level currently used. This has to be confirmed in clinical studies and possible differences depending on lesion type should be further examined. PMID:17704316

  3. Potential for dose-escalation and reduction of risk in pancreatic cancer using IMRT optimization with lexicographic ordering and gEUD-based cost functions

    SciTech Connect

    Spalding, Aaron C.; Jee, Kyung-Wook; Vineberg, Karen; Jablonowski, Marla; Fraass, Benedick A.; Pan, Charlie C.; Lawrence, Theodore S.; Ten Haken, Randall K.; Ben-Josef, Edgar

    2007-02-15

    Radiotherapy for pancreatic cancer is limited by the tolerance of local organs at risk (OARs) and frequent overlap of the planning target volume (PTV) and OAR volumes. Using lexicographic ordering (LO), a hierarchical optimization technique, with generalized equivalent uniform dose (gEUD) cost functions, we studied the potential of intensity modulated radiation therapy (IMRT) to increase the dose to pancreatic tumors and to areas of vascular involvement that preclude surgical resection [surgical boost volume (SBV)]. We compared 15 forward planned three-dimensional conformal (3DCRT) and IMRT treatment plans for locally advanced unresectable pancreatic cancer. We created IMRT plans optimized using LO with gEUD-based cost functions that account for the contribution of each part of the resulting inhomogeneous dose distribution. LO-IMRT plans allowed substantial PTV dose escalation compared with 3DCRT; median increase from 52 Gy to 66 Gy (a=-5,p<0.005) and median increase from 50 Gy to 59 Gy (a=-15,p<0.005). LO-IMRT also allowed increases to 85 Gy in the SBV, regardless of a value, along with significant dose reductions in OARs. We conclude that LO-IMRT with gEUD cost functions could allow dose escalation in pancreas tumors with concomitant reduction in doses to organs at risk as compared with traditional 3DCRT.

  4. 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.

  5. Radiation dose reduction using a neck detection algorithm for single spiral brain and cervical spine CT acquisition in the trauma setting.

    PubMed

    Ardley, Nicholas D; Lau, Ken K; Buchan, Kevin

    2013-12-01

    Cervical spine injuries occur in 4-8 % of adults with head trauma. Dual acquisition technique has been traditionally used for the CT scanning of brain and cervical spine. The purpose of this study was to determine the efficacy of radiation dose reduction by using a single acquisition technique that incorporated both anatomical regions with a dedicated neck detection algorithm. Thirty trauma patients for brain and cervical spine CT were included and were scanned with the single acquisition technique. The radiation doses from the single CT acquisition technique with the neck detection algorithm, which allowed appropriate independent dose administration relevant to brain and cervical spine regions, were recorded. Comparison was made both to the doses calculated from the simulation of the traditional dual acquisitions with matching parameters, and to the doses of retrospective dual acquisition legacy technique with the same sample size. The mean simulated dose for the traditional dual acquisition technique was 3.99 mSv, comparable to the average dose of 4.2 mSv from 30 previous patients who had CT of brain and cervical spine as dual acquisitions. The mean dose from the single acquisition technique was 3.35 mSv, resulting in a 16 % overall dose reduction. The images from the single acquisition technique were of excellent diagnostic quality. The new single acquisition CT technique incorporating the neck detection algorithm for brain and cervical spine significantly reduces the overall radiation dose by eliminating the unavoidable overlapping range between 2 anatomical regions which occurs with the traditional dual acquisition technique.

  6. Genotypes of CYP2C8 and FGD4 and their association with peripheral neuropathy or early dose reduction in paclitaxel-treated breast cancer patients.

    PubMed

    Lam, Siu W; Frederiks, Charlotte N; van der Straaten, Tahar; Honkoop, Aafke H; Guchelaar, Henk-Jan; Boven, Epie

    2016-11-22

    The purpose of this study was to evaluate single-nucleotide polymorphisms (SNPs) in genes encoding key metabolising enzymes or involved in pharmacodynamics for possible associations with paclitaxel-induced peripheral neuropathy. The study population consists of 188 women from the multicenter, randomised, phase II ATX trial (BOOG2006-06; EudraCT number 2006-006058-83) that received paclitaxel and bevacizumab without or with capecitabine as first-line palliative therapy of HER2-negative metastatic breast cancer. Genotyping of CYP2C8*3 (c.416G>A), CYP3A4*22 (c.522-191C>T), TUBB2A (c.-101T>C), FGD4 (c.2044-236G>A) and EPHA5 (c.2895G>A) was performed by real-time PCR. Toxicity endpoints were cumulative dose (1) until first onset of grade ⩾1 peripheral neuropathy and (2) until first paclitaxel dose reduction from related toxicity (NCI-CTCAE version 3.0). SNPs were evaluated using the Kaplan-Meier method, the Gehan-Breslow-Wilcoxon test and the multivariate Cox regression analysis. The rate of grade ⩾1 peripheral neuropathy was 67% (n=126). The rate of dose reduction was 46% (n=87). Age ⩾65 years was a risk factor for peripheral neuropathy (HR=1.87, P<0.008), but not for dose reduction. When adjusted for age, body surface area and total cumulative paclitaxel dose, CYP2C8*3 carriers had an increased risk of peripheral neuropathy (HR=1.59, P=0.045). FGD4 c.2044-236 A-allele carriers had an increased risk of paclitaxel dose reduction (HR per A-allele=1.38, P=0.036) when adjusted for total cumulative paclitaxel dose. These findings may point towards clinically useful indicators of early toxicity, but warrant further investigation.

  7. Effect of reduction of the pulse rates of fluoroscopy and CINE-acquisition on x-ray dose and angiographic image quality during invasive cardiovascular procedures.

    PubMed

    Pyne, Christopher T; Gadey, Gautam; Jeon, Cathy; Piemonte, Thomas; Waxman, Sergio; Resnic, Frederic

    2014-08-01

    Reducing digital pulse rates (PR) are known to reduce total energy during invasive cardiovascular procedures, which likely has benefits for patients and staff. Physicians may be reluctant to reduce these parameters because they fear a decline in image quality that could affect procedural outcomes. We sought to assess the effect of default rates of fluoroscopy (Fluoro) and CINE-acquisition (CINE) on total x-ray dose and image quality during invasive cardiovascular procedures. We retrospectively reviewed procedures done with 2 default PRs: a standard dose cohort (PR, 15 for Fluoro and CINE), and a reduced dose cohort (PR, 10 for Fluoro and CINE). Total x-ray dose, Fluoro time, and contrast use were compared between groups. A blinded angiographic image quality assessment was then performed using an objective 10-point angiographic quality score. There were no significant differences between cohorts for fluoroscopy time or contrast use. The reduced dose cohort has a significant reduction in mean total x-ray dose (PR 15, 1763.1 mGy; PR 10, 1179.1 mGy; P<0.0001). When adjusted for potential confounders, a 38% reduction in total x-ray dose was identified (P<0.0001). There was no difference in adjusted angiographic quality score between the cohorts (PR 15, 7.90; PR 10, 8.00; P=0.67), indicating no decline in image quality with PR reduction. Reducing default PRs during invasive cardiovascular procedures yields large and significant reductions in total x-ray energy with no decline in angiographic image quality. © 2014 American Heart Association, Inc.

  8. Feasibility of patient dose reduction based on various noise suppression filters for cone-beam computed tomography in an image-guided patient positioning system

    NASA Astrophysics Data System (ADS)

    Kamezawa, Hidemi; Arimura, Hidetaka; Shirieda, Katsutoshi; Kameda, Noboru; Ohki, Masafumi

    2016-05-01

    We investigated the feasibility of patient dose reduction based on six noise suppression filters for cone-beam computed tomography (CBCT) in an image-guided patient positioning (IGPP) system. A midpoint dose was employed as a patient dose index. First, a reference dose (RD) and low-dose (LD)-CBCT images were acquired with a reference dose and various low doses. Second, an automated rigid registration was performed for three axis translations to estimate patient setup errors between a planning CT image and the LD-CBCT images processed by six noise suppression filters (averaging filter, median filter, Gaussian filter, edge-preserving smoothing filter, bilateral filter, and adaptive partial median filter (AMF)). Third, residual errors representing the patient positioning accuracy were calculated as Euclidean distances between the setup error vectors estimated using the LD-CBCT and RD-CBCT images. Finally, the residual errors as a function of the patient dose index were estimated for LD-CBCT images processed by six noise suppression filters, and then the patient dose indices for the filtered LD-CBCT images were obtained at the same residual error as the RD-CBCT image. This approach was applied to an anthropomorphic phantom and four cancer patients. The patient dose for the LD-CBCT images was reduced to 19% of that for the RD-CBCT image for the phantom by using AMF, while keeping a same residual error of 0.47 mm as the RD-CBCT image by applying the noise suppression filters to the LD-CBCT images. The average patient dose was reduced to 31.1% for prostate cancer patients, and it was reduced to 82.5% for a lung cancer patient by applying the AMF. These preliminary results suggested that the proposed approach based on noise suppression filters could decrease the patient dose in IGPP systems.

  9. A double-blind randomized clinical trial of different doses of transdermal nicotine patch for smoking reduction and cessation in long-term hospitalized schizophrenic patients.

    PubMed

    Chen, Hsing-Kang; Lan, Tsuo-Hung; Wu, Bo-Jian

    2013-02-01

    There have been many studies of smoking cessation using nicotine replacement therapy (NRT) with schizophrenic patients, but none exploring the smoking-reduction effects of varying doses of NRT in long-stay patients with schizophrenia. This study aimed to examine the effect of different doses of the nicotine transdermal patch on smoking-reduction and cessation outcomes in long-term hospitalized schizophrenic patients. A total of 184 subjects participated in a randomized, controlled, double-blind 8-week clinical trial. Participants were randomized into two groups using two different doses of NRT: a high-dose NRT group (31.2 mg for the first 4 weeks, then 20.8 mg for 4 weeks, n = 92) or a low-dose NRT group (20.8 mg for 8 weeks, n = 92). The 7-day point prevalence of abstinence was 2.7 % (5/184). Participants in the low-dose NRT group reduced smoking by 3.1 more cigarettes on average than those in the high-dose group (p = 0.005). However, a repeated measures analysis of variance revealed that the main effect of changes in the number of cigarettes smoked, comparing the two types of treatment across periods, was not significant (p = 0.35, partial eta square = 0.018). In summary, among a cohort of chronic institutionalized schizophrenic patients, smoking cessation and reduction outcomes were not correlated with NRT dose, and the cessation rate was much lower than rates in similar studies. It indicates that long-term hospitalized schizophrenic patients have more difficulties with quitting smoking. More effective integrative smoking cessation programs should be addressed for these patients.

  10. NIH-funded study shows 20 percent reduction in lung cancer mortality with low-dose CT compared to chest X-ray: | Division of Cancer Prevention

    Cancer.gov

    Scientists have found a 20 percent reduction in deaths from lung cancer among current or former heavy smokers who were screened with low-dose helical computed tomography (CT) versus those screened by chest X-ray. The primary research results from the National Lung Screening Trial (NLST) were published online today in the New England Journal of Medicine. |

  11. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    SciTech Connect

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-03-15

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

  12. Reductive dechlorination of chlorinated hydrocarbons as non-aqueous phase liquid (NAPL): preliminary investigation on effects of cement doses.

    PubMed

    Do, Si-Hyun; Batchelor, Bill

    2012-07-15

    The reactivities of various types of iron mixtures to degrade chlorinated hydrocarbons (PCE, TCE and 1,1,1-TCA) in the form of non-aqueous phase liquids were investigated. The iron mixtures included a mixture of Fe(II) and Portland cement (Fe(II)-C), a mixture of Fe(II), Fe(III) and Ca(OH)(2) (Fe(II/III)-L), and a mixture of Fe(II), Fe(III), Ca(OH)(2), and Portland cement (Fe(II/III)-C). When the same amount of Fe(II) was used, Fe(II)-C was more reactive with chlorinated ethylenes (i.e. PCE and TCE) than Fe(II/III)-L. The reductive pathway for high concentrations of total PCE (i.e. above solubility) with Fe(II)-C was determined to be a combination of two-electron transfer, β-elimination and hydrogenolysis. Increasing the cement dose from 5% to 10% in Fe(II)-C did not affect PCE dechlorination rates, but it did favor the β-elimination pathway. In addition, when Fe(II/III)-C with 5%C was used, PCE dechlorination was similar to that by Fe(II)-C, but this mixture did not effectively degrade TCE. A modified second-order kinetic model was developed and shown to appropriately describe degradation of TCE at high concentrations. Fe(II/III)-L effectively degraded high concentrations of 1,1,1-TCA at rates that were similar to those obtained with Fe(II)-C using 10% C. Moreover, both increasing cement doses and the presence of Fe(III) increased dechlorination rates of 1,1,1-TCA, which was mainly through the hydrogenolysis pathway. The reactivity of Fe(II/III)-L was strongly dependent on the target compound (i.e. less reactivity with TCE, more with 1,1,1-TCA). Therefore, Fe(II/III)-L could be a potential mixture for degrading 1,1,1-TCA, but it should be modified to degrade TCE more effectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    PubMed Central

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-01-01

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

  14. Angular on-line tube current modulation in multidetector CT examinations of children and adults: The influence of different scanning parameters on dose reduction

    SciTech Connect

    Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

    2007-07-15

    The purpose of this study was to assess the potential of angular on-line tube current modulation on dose reduction in pediatric and adult patients undergoing multidetector computed tomography (MDCT) examinations. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-year-old, 5-year-old, 10-year-old, and adult were employed in the current study. Phantoms were scanned with the use of on-line tube current modulation (TCM). Percent dose reduction (%DR) factors achieved by applying TCM, were determined for standard protocols used for head and neck, shoulder, thorax, thorax and abdomen, abdomen, abdomen and pelvis, pelvis, and whole body examinations. A preliminary study on the application of TCM in MDCT examinations of adult patients was performed to validate the results obtained in anthropomorphic phantoms. Dose reduction was estimated as the percentage difference of the modulated milliamperes for each scan and the preset milliamperes prescribed by the scan protocol. The dose reduction in children was found to be much lower than the corresponding reduction achieved for adults. For helical scans the %DR factors, ranged between 1.6% and 7.4% for the neonate, 2.9% and 8.7% for the 1-year old, 2% and 6% for the 5-year-old, 5% and 10.9% for the 10-year-old, and 10.4% and 20.7% for the adult individual. For sequential scans the corresponding %DR factors ranged between 1.3% and 6.7%, 4.5% and 11%, 4.2% and 6.6%, 6.4% and 12.3%, and 8.9% and 23.3%, respectively. Broader beam collimations are associated with decreased %DR factors, when other scanning parameters are held constant. TCM did not impair image noise. In adult patients, the %DR values were found to be in good agreement with the corresponding results obtained in the anthropomorphic adult phantom. In conclusion, on-line TCM may be considered as a valuable tool for reducing dose in routine CT examinations of pediatric and adult patients. However, the dose reduction achieved with TCM

  15. Dose reduction in spiral CT coronary angiography with dual source equipment. Part II. Dose surplus due to slope-up and slope-down of prospective tube current modulation in a phantom model.

    PubMed

    Martini, C; Palumbo, A; Maffei, E; Rossi, A; Rengo, M; Malagò, R; Dijkshoorn, M; Weustink, A; Mollet, N; Krestin, G; Cademartiri, F

    2010-02-01

    This study was undertaken to estimate surplus radiation dose in retrospectively electrocardiography (ECG)-gated dual-source computed tomography coronary angiography (DSCT-CA) due to the slope-up and slope-down of the tube current using prospectively ECG-triggered tube modulation. We used an anthropomorphic phantom with an ECG-gated retrospective protocol and a DSCT scanner (Definition, Siemens). We used four tube current modulation algorithms: narrow pulsing window, with tube current reduction to 20% (A) and 4% (B) of peak current; and wide pulsing window, with tube current reduction to 20% (C) and 4% (D). Each algorithm was applied at five heart rates (HR=45, 60, 75, 90 and 120 bpm) with adaptive pitch values (0.2-0.5). Data sets were reconstructed in 5% increments from 0-95% of the R-R interval. Noise was measured at each R-R step in order to identify low noise (100% dose), medium noise (slope-up/down) and high noise (4/20% dose). Width of the transition window (slope-up/slope-down from 4/20% to 100% dose) was calculated. The surplus dose due to slope-up/slope-down was calculated. Surplus dose was 19% (A), 34% (B), 14% (C) and 21% (D). The transition window lasted 10%+10% (slope-up + down) for HR <75 bpm and all HR in C (except for 120 bpm; 25%+15%), 15%+15% for HR >90 bpm (A). For C and D, instead, the slope-up increased with progressively higher HR (10%-25% of the R-R interval, except for 90 bpm, 10%), whereas the slope-down remained constant at 5% (except for 120 bpm; 10%). The adaptive ECG-pulsing windows produced an increment of the surplus dose with increasing HR. The transition window was a constant source of surplus radiation dose in the range of 14%-34%.

  16. Comparison of the effects of low dose interferon and high dose interferon on reduction of the number and size of plaques in patients with Multiple Sclerosis: A historical cohort.

    PubMed

    Khomand, Payam; Moradi, Ghobad; Ahsan, Behrooz; Abtahi, Setareh

    2017-01-05

    Background: This study was performed to compare the effects of low dose interferon beta-1 (IFN-β-1) (CinnoVex, 30 mcg) and high dose IFN-β-1 (REBIF, 44 mcg) on the reduction of the number and size of plaques in magnetic resonance imaging (MRI) in patients with multiple sclerosis (MS). Methods: This historical cohort study, which was performed in 2014 in Sanandaj (western part of Iran). 43 MS patients in two groups were investigated. The first group, which included 19 patients, was treated using high dose IFN (44 mcg) and the second group, which was consisted of 24 patients, was treated using low dose IFN (30 mcg). Patients' data were collected and analyzed by the Stata version 11 software; the analyses were performed using statistical t-test, chi-square test, Fisher test, and logistic regression. Results: Both drugs were effective in controlling active demyelinating plaque and in preventing plaque activation (P = 0.633). The impact of both drugs in the reduction of the number and size of plaques was evaluated. Based on the results of the MRI, high dose IFN therapy was more effective than the low dose IFN drugs and had a better performance in terms of reducing the number of plaques and in stop-and-recovery (P = 0.039), as well as in reducing the plaque size (P = 0.050). Conclusion: The high dose IFN therapy was more effective than the low dose IFN therapy in reducing the number and size of brain plaques in patients with relapsing-remitting MS (RRMS).

  17. The Impact of Azilsartan Medoxomil Treatment (Capsule Formulation) at Doses Ranging From 10 to 80 mg: Significant, Rapid Reductions in Clinic Diastolic and Systolic Blood Pressure.

    PubMed

    Perez, Alfonso; Cao, Charlie

    2017-03-01

    In this phase 2, multicenter, parallel-group, double-blind, dose-ranging study, hypertensive adults (n=449) were randomized to receive one of five doses of a capsule formulation of azilsartan medoxomil (AZL-M; 5, 10, 20, 40, 80 mg), olmesartan medoxomil (OLM) 20 mg, or placebo once daily. The primary endpoint was change in trough clinic diastolic blood pressure (DBP) at week 8. AZL-M provided rapid statistically and clinically significant reductions in DBP and systolic blood pressure (SBP) vs placebo at all doses except 5 mg. Placebo-subtracted changes were greatest with the 40 mg dose (DBP, -5.7 mm Hg; SBP, -12.3 mm Hg). Clinic changes with AZL-M (all doses) were statistically indistinguishable vs OLM, although there were greater reductions with AZL-M 40 mg using 24-hour ambulatory blood pressure. Adverse event frequency was similar in the AZL-M and placebo groups. Based on these and other findings, subsequent trials investigated the commercial AZL-M tablet in the dose range of 20 to 80 mg/d. ©2016 Wiley Periodicals, Inc.

  18. 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.

  19. SU-F-I-09: Improvement of Image Registration Using Total-Variation Based Noise Reduction Algorithms for Low-Dose CBCT

    SciTech Connect

    Mukherjee, S; Farr, J; Merchant, T; Yao, W

    2016-06-15

    Purpose: To study the effect of total-variation based noise reduction algorithms to improve the image registration of low-dose CBCT for patient positioning in radiation therapy. Methods: In low-dose CBCT, the reconstructed image is degraded by excessive quantum noise. In this study, we developed a total-variation based noise reduction algorithm and studied the effect of the algorithm on noise reduction and image registration accuracy. To study the effect of noise reduction, we have calculated the peak signal-to-noise ratio (PSNR). To study the improvement of image registration, we performed image registration between volumetric CT and MV- CBCT images of different head-and-neck patients and calculated the mutual information (MI) and Pearson correlation coefficient (PCC) as a similarity metric. The PSNR, MI and PCC were calculated for both the noisy and noise-reduced CBCT images. Results: The algorithms were shown to be effective in reducing the noise level and improving the MI and PCC for the low-dose CBCT images tested. For the different head-and-neck patients, a maximum improvement of PSNR of 10 dB with respect to the noisy image was calculated. The improvement of MI and PCC was 9% and 2% respectively. Conclusion: Total-variation based noise reduction algorithm was studied to improve the image registration between CT and low-dose CBCT. The algorithm had shown promising results in reducing the noise from low-dose CBCT images and improving the similarity metric in terms of MI and PCC.

  20. SU-E-T-373: Evaluation and Reduction of Contralateral Skin /subcutaneous Dose for Tangential Breast Irradiation

    SciTech Connect

    Butson, M; Carroll, S; Whitaker, M; Odgers, D; Martin, D; Hinds, S; Kader, J; Ho, K; Amos, S; Toohey, J

    2015-06-15

    Purpose: Tangential breast irradiation is a standard treatment technique for breast cancer therapy. One aspect of dose delivery includes dose delivered to the skin caused by electron contamination. This effect is especially important for highly oblique beams used on the medical tangent where the electron contamination deposits dose on the contralateral breast side. This work aims to investigate and predict as well as define a method to reduce this dose during tangential breast radiotherapy. Methods: Analysis and calculation of breast skin and subcutaneous dose is performed using a Varian Eclipse planning system, AAA algorithm for 6MV x-ray treatments. Measurements were made using EBT3 Gafchromic film to verify the accuracy of planning data. Various materials were tested to assess their ability to remove electron contamination on the contralateral breast. Results: Results showed that the Varian Eclipse AAA algorithm could accurately estimate contralateral breast dose in the build-up region at depths of 2mm or deeper. Surface dose was underestimated by the AAA algorithm. Doses up to 12% of applied dose were seen on the contralateral breast surface and up to 9 % at 2mm depth. Due to the nature of this radiation, being mainly low energy electron contamination, a bolus material could be used to reduce this dose to less than 3%. This is accomplished by 10 mm of superflab bolus or by 1 mm of lead. Conclusion: Contralateral breast skin and subcutaneous dose is present for tangential breast treatment and has been measured to be up to 12% of applied dose from the medial tangent beam. This dose is deposited at shallow depths and is accurately calculated by the Eclipse AAA algorithm at depths of 2mm or greater. Bolus material placed over the contralateral can be used to effectively reduce this skin dose.

  1. Examining Margin Reduction and Its Impact on Dose Distribution for Prostate Cancer Patients Undergoing Daily Cone-Beam Computed Tomography

    SciTech Connect

    Hammoud, Rabih Patel, Samir H.; Pradhan, Deepak; Kim, Jinkoo; Guan, Harrison; Li Shidong; Movsas, Benjamin

    2008-05-01

    Purpose: To examine the dosimetric impact of margin reduction and quantify residual error after three-dimensional (3D) image registration using daily cone-beam computed tomography (CBCT) for prostate cancer patients. Methods and Materials: One hundred forty CBCTs from 5 prostate cancer patients were examined. Two intensity-modulated radiotherapy plans were generated on CT simulation on the basis of two planning target volume (PTV) margins: 10 mm all around the prostate and seminal vesicles except 6 mm posteriorly (10/6) and 5 mm all around except 3 mm posteriorly (5/3). Daily CBCT using the Varian On-Board Imaging System was acquired. The 10/6 and 5/3 simulation plans were overlaid onto each CBCT, and each CBCT plan was calculated. To examine residual error, PlanCT/CBCT intensity-based 3D image registration was performed for prostate localization using center of mass and maximal border displacement. Results: Prostate coverage was within 2% between the 10/6 and 5/3 plans. Seminal vesicle coverage was reduced with the 5/3 plan compared with the 10/6 plan, with coverage difference within 7%. The 5/3 plan allowed 30-50% sparing of bladder and rectal high-dose regions. For residual error quantification, center of mass data show that 99%, 93%, and 96% of observations fall within 3 mm in the left-right, anterior-posterior, and superior-inferior directions, respectively. Maximal border displacement observations range from 79% to 99%, within 5 mm for all directions. Conclusion: Cone-beam CT dosimetrically validated a 10/6 margin when soft-tissue localization is not used. Intensity-based 3D image registration has the potential to improve target localization and to provide guidelines for margin definition.

  2. Exhaling a budesonide inhaler through the nose results in a significant reduction in dose requirement of budesonide nasal spray in patients having asthma with rhinitis.

    PubMed

    Shaikh, W A

    1999-01-01

    Budesonide, an inhaled corticosteroid is used routinely in the treatment of bronchial asthma and rhinitis. Although inhaled corticosteroids in therapeutic doses are unlikely to result in systemic side effects, there is as yet skepticism about their routine and prolonged use. The aim of this study was to determine whether budesonide inhalation through a metered dose inhaler, when exhaled through the nose could result in a reduction in the dose requirement of budesonide metered nasal spray in patients having perennial allergic asthma with rhinitis. This study was an open, parallel, comparative, crossover trial in which 49 young patients having perennial allergic asthma with rhinitis were divided into two groups and administered either a combination of budesonide metered dose inhaler with a budesonide nasal spray or a budesonide inhaler alone, which was to be exhaled through the nose. Both groups were later crossed over and weekly symptom scores and peak nasal inspiratory flow rates were monitored during each phase of the study. Finally, patients who volunteered from both groups were instructed to note the reduction in dose requirement of budesonide nasal spray while using a budesonide inhaler and exhaling it through the nose. The results of this study reveal that when a budesonide inhaler is exhaled through the nose, it results in an improvement in symptom scores and peak nasal inspiratory flow rates, which were significantly less than those obtained in the group using both a budesonide nasal spray and a metered dose inhaler. In addition, exhaling budesonide through the nose results in a 40.1% reduction in the dose requirement of a budesonide nasal spray, which is statistically significant (p < 0.001).

  3. Sci—Fri AM: Mountain — 02: A comparison of dose reduction methods on image quality for cone beam CT

    SciTech Connect

    Webb, R; Buckley, LA

    2014-08-15

    Modern radiotherapy uses highly conformai dose distributions and therefore relies on daily image guidance for accurate patient positioning. Kilovoltage cone beam CT is one technique that is routinely used for patient set-up and results in a high dose to the patient relative to planar imaging techniques. This study uses an Elekta Synergy linac equipped with XVI cone beam CT to investigate the impact of various imaging parameters on dose and image quality. Dose and image quality are assessed as functions of x-ray tube voltage, tube current and the number of projections in the scan. In each case, the dose measurements confirm that as each parameter increases the dose increases. The assessment of high contrast resolution shows little dependence on changes to the image technique. However, low contrast visibility suggests a trade off between dose and image quality. Particularly for changes in tube potential, the dose increases much faster as a function of voltage than the corresponding increase in low contrast image quality. This suggests using moderate values of the peak tube voltage (100 – 120 kVp) since higher values result in significant dose increases with little gain in image quality. Measurements also indicate that increasing tube current achieves the greatest degree of improvement in the low contrast visibility. The results of this study highlight the need to establish careful imaging protocols to limit dose to the patient and to limit changes to the imaging parameters to those cases where there is a clear clinical requirement for improved image quality.

  4. Low-dose head computed tomography in children: a single institutional experience in pediatric radiation risk reduction: clinical article.

    PubMed

    Morton, Ryan P; Reynolds, Renee M; Ramakrishna, Rohan; Levitt, Michael R; Hopper, Richard A; Lee, Amy; Browd, Samuel R

    2013-10-01

    In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Children's Hospital), the largest number of patients with this protocol reported to date. All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan. Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Children's Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%. The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

  5. [Adherence of type 2 diabetes patients on insulin analogues application: missed dose, time imprecision and dose reduction. The results of GAPP2TM(Global Attitudes of Physicians and Patient) survey in the Czech Republic].

    PubMed

    Prázný, Martin

    2014-11-01

    Irregular insulin dose is one of the main problems associated with insulin therapy in patients with type 2 diabetes; its extent is not known precisely. The aim of survey conducted in the Czech Republic in the international project GAPP2 - Global Attitudes of Patients and Physicians was to determine the incidence and the impact of irregular use of basal insulin analogues in patients with type 2 diabetes, to point out the reasons for these irregularities and to focus on how physicians discuss irregular application of insulin with patients. The project GAPP2 is an international cross-sectional study performed on-line via the Internet using a questionnaire filled by diabetic patients treated with insulin analogues and physicians who treat these patients. The survey was conducted in two steps in 17 countries; the first step included 6 countries and was completed in the beginning of 2012, the second step involved 11 other countries including the Czech Republic with termination in 2014. The survey was designed to obtain the views of patients and physicians on certain aspects of insulin treatment and persistent issues in this field in the real daily practice. Special focus was on the incidence and management of hypoglycaemia as well as on irregularities of insulin application. In the part dedicated to adherence to basal insulin application were observed three types of irregular insulin therapy: missed dose, time imprecision of dose (± 2 hours vs. the prescribed time) and dose reduction in all cases in the past 30 days before completing the questionnaire. In addition, it was investigated the attitude and relation of patients to these issues. The results have shown that irregular insulin dose in the Czech Republic is less frequent than in other countries involved in the GAPP2 research. Nevertheless, approximately one fifth of diabetic patients using insulin analogues in basal-bolus or only basal therapy regimen is related to this problem. The last irregular insulin

  6. Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes

    SciTech Connect

    Al-Affan, I. A. M. Hugtenburg, R. P.; Piliero, M.; Bari, D. S.; Al-Saleh, W. M.; Evans, S.; Al-Hasan, M.; Al-Zughul, B.; Al-Kharouf, S.; Ghaith, A.

    2015-02-15

    Purpose: This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. Methods: Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scattered photons at the maze entrance. The dose of the backscattered photons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. Results: It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscattered photons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. Conclusions: This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.

  7. Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes.

    PubMed

    Al-Affan, I A M; Hugtenburg, R P; Bari, D S; Al-Saleh, W M; Piliero, M; Evans, S; Al-Hasan, M; Al-Zughul, B; Al-Kharouf, S; Ghaith, A

    2015-02-01

    This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scattered photons at the maze entrance. The dose of the backscattered photons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscattered photons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose. © 2015 American Association of Physicists in Medicine.

  8. Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes.

    PubMed

    Al-Affan, I A M; Hugtenburg, R P; Bari, D S; Al-Saleh, W M; Piliero, M; Evans, S; Al-Hasan, M; Al-Zughul, B; Al-Kharouf, S; Ghaith, A

    2015-02-01

    This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scatteredphotons at the maze entrance. The dose of the backscatteredphotons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscatteredphotons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.

  9. Systematic Evaluation of Radiation Dose Reduction in CT Studies of Body Packers: Accuracy Down to Submillisievert Levels.

    PubMed

    Laberke, Patrick J; Blum, Simon; Waelti, Stephan; Fornaro, Jürgen; Hausmann, Roland; Alkadhi, Hatem; Leschka, Sebastian

    2016-04-01

    The objective of this study was to systematically evaluate the accuracy of abdominal CT performed at different radiation dose levels for the detection of body packs in human cadavers, in comparison with the accuracy of abdominal radiography. In this study, differing numbers of body packs (range, 0-20) were placed in the alimentary tract of human cadavers and then underwent imaging with abdominal radiography and with CT performed at different radiation dose levels (ranging from the standard abdominal CT dose to the technical minimum dose). Depiction of body packs on abdominal radiographs and on each CT scan was assessed by two independent blinded radiologists, and the accuracy of detection of body packs was calculated. The radiation dose associated with abdominal radiography was measured, and the effective radiation dose associated with CT was estimated. The mean (± SD) effective radiation dose for abdominal radiography was 1.4 ± 0.3 mSv, whereas the mean effective dose of CT ranged from 0.1 to 9.6 mSv. Interobserver agreement for body pack detection was moderate (κ = 0.51) for abdominal radiography and good (κ = 0.72-0.85) for CT. In a per-body pack analysis, abdominal radiography depicted 42% of the body packs with a sensitivity of 71% and a specificity of 100%. When performed at radiation dose levels of 0.6 mSv or greater, CT correctly detected all body packs. In per-person analysis, the sensitivity and specificity of CT for the correct detection of at least one body pack per cadaver was 100% for all radiation dose levels. CT performed at a dose of 0.6 mSv can be used for the detection of body packs. With a sensitivity and specificity of 100%, CT is superior to abdominal radiography in terms of reliability, associated radiation dose, and accuracy of detection.

  10. A study on the dependence of exposure dose reduction and image evaluation on the distance from the dental periapical X-ray machine

    NASA Astrophysics Data System (ADS)

    Joo, Kyu-Ji; Shin, Jae-Woo; Dong, Kyung-Rae; Lim, Chang-Seon; Chung, Woon-Kwan; Kim, Young-Jae

    2013-11-01

    Reducing the exposure dose from a periapical X-ray machine is an important aim in dental radiography. Although the radiation exposure dose is generally low, any radiation exposure is harmful to the human body. Therefore, this study developed a method that reduces the exposure dose significantly compared to that encountered in a normal procedure, but still produces an image with a similar resolution. The correlation between the image resolution and the exposure dose of the proposed method was examined with increasing distance between the dosimeter and the X-ray tube. The results were compared with those obtained from the existing radiography method. When periapical radiography was performed once according to the recommendations of the International Commission on Radiological Protection (ICRP), the measured skin surface dose was low at 7 mGy or below. In contrast, the skin surface dose measured using the proposed method was only 1.57 mGy, showing a five-fold reduction. These results suggest that further decreases in dose might be achieved using the proposed method.

  11. A combination of spatial and recursive temporal filtering for noise reduction when using region of interest (ROI) fluoroscopy for patient dose reduction in image guided vascular interventions with significant anatomical motion

    NASA Astrophysics Data System (ADS)

    Setlur Nagesh, S. V.; Khobragade, P.; Ionita, C.; Bednarek, D. R.; Rudin, S.

    2015-03-01

    Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bioprosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions.

  12. A Combination of Spatial and Recursive Temporal Filtering for Noise Reduction when Using Region of Interest (ROI) Fluoroscopy for Patient Dose Reduction in Image Guided Vascular Interventions with Significant Anatomical Motion

    PubMed Central

    Nagesh, S.V. Setlur; Khobragade, P.; Ionita, C.; Bednarek, D.R; Rudin, S.

    2015-01-01

    Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bio-prosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions. PMID:26900203

  13. A Combination of Spatial and Recursive Temporal Filtering for Noise Reduction when Using Region of Interest (ROI) Fluoroscopy for Patient Dose Reduction in Image Guided Vascular Interventions with Significant Anatomical Motion.

    PubMed

    Nagesh, S V Setlur; Khobragade, P; Ionita, C; Bednarek, D R; Rudin, S

    2015-02-21

    Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bio-prosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions.

  14. Intravenous Ketamine for Rapid Opioid Dose Reduction, Reversal of Opioid-Induced Neurotoxicity, and Pain Control in Terminal Care: Case Report and Literature Review.

    PubMed

    Winegarden, Jennifer; Carr, Daniel B; Bradshaw, Ylisabyth S

    2016-04-01

    We report a case of opioid-induced neurotoxicity (OIN) in an actively dying hospice patient, its reversal and improved analgesia that followed opioid dosage reduction made possible after addition of IV ketamine. We briefly review the diagnosis and treatment of OIN. OIN, particularly when associated with high dose opioid therapy in palliative care, may pose difficult diagnostic and treatment challenges. Few publications from end-of-life settings provide systematic approaches to management of OIN. We describe a case of OIN in a hospice patient receiving medical care at home while actively dying. Addition of IV ketamine and reduction of the patient's high-dose opioid regimen. The patient's pain was controlled within 24 hours of initiation of IV ketamine while the total opioid dose was reduced. His symptoms of OIN (delirium, tremor, myoclonus, and hallucinations) also rapidly subsided. OIN should be considered as an etiology of CNS dysfunction occurring with prolonged, high-dose opioid therapy. This case highlights the opioid-sparing and analgesic properties of low-dose ketamine, allowing reversal of OIN in the home hospice setting. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Spatial resolution improvement and dose reduction potential for inner ear CT imaging using a z-axis deconvolution technique.

    PubMed

    McCollough, Cynthia H; Leng, Shuai; Sunnegardh, Johan; Vrieze, Thomas J; Yu, Lifeng; Lane, John; Raupach, Rainer; Stierstorfer, Karl; Flohr, Thomas

    2013-06-01

    To assess the z-axis resolution improvement and dose reduction potential achieved using a z-axis deconvolution technique with iterative reconstruction (IR) relative to filtered backprojection (FBP) images created with the use of a z-axis comb filter. Each of three phantoms were scanned with two different acquisition modes: (1) an ultrahigh resolution (UHR) scan mode that uses a comb filter in the fan angle direction to increase in-plane spatial resolution and (2) a z-axis ultrahigh spatial resolution (zUHR) scan mode that uses comb filters in both the fan and cone angle directions to improve both in-plane and z-axis spatial resolution. All other scanning parameters were identical. First, the ACR CT Accreditation phantom, rotated by 90° so that the high-contrast spatial resolution targets were parallel to the coronal plane, was scanned to assess limiting spatial resolution and image noise. Second, section sensitivity profiles (SSPs) were measured using a copper foil embedded in an acrylic cylinder and the full-width-at-half-maximum (FWHM) and full-width-at-tenth-maximum (FWTM) of the SSPs were calculated. Third, an anthropomorphic head phantom containing a human skull was scanned to assess clinical acceptability for imaging of the temporal bone. For each scan, FBP images were reconstructed for the zUHR scan using the narrowest image thickness available. For the CT accreditation phantom, zUHR images were also reconstructed using an IR algorithm (SAFIRE, Siemens Healthcare, Forchheim, Germany) to assess the influence of the IR algorithm on image noise. A z-axis deconvolution technique combined with the IR algorithm was used to reconstruct images at the narrowest image thickness possible from the UHR scan data. Images of the ACR and head phantoms were reformatted into the coronal plane. The head phantom images were evaluated by a neuroradiologist to assess acceptability for use in patients undergoing clinically indicated CT imaging of the temporal bone. The limiting

  16. Massive reduction of tumour load and normalisation of hyperprolactinaemia after high dose cabergoline in metastasised prolactinoma causing thoracic syringomyelia

    PubMed Central

    van Uum, S H M; van Alfen, N; Wesseling, P; van Lindert, E; Pieters, G; Nooijen, P; Hermus, A

    2004-01-01

    On administration of high dose cabergoline, 0.5 mg twice a day orally, the plasma prolactin levels decreased within one month and then normalised within 26 months. Tumour load reduced considerably but unfortunately, her signs and symptoms did not improve. This case illustrates that a high dose dopamine agonist might be an important therapeutic option in patients with a metastasised prolactinoma. PMID:15377706

  17. On the dosimetric effect and reduction of inverse consistency and transitivity errors in deformable image registration for dose accumulation

    SciTech Connect

    Bender, Edward T.; Hardcastle, Nicholas; Tome, Wolfgang A.

    2012-01-15

    Purpose: Deformable image registration (DIR) is necessary for accurate dose accumulation between multiple radiotherapy image sets. DIR algorithms can suffer from inverse and transitivity inconsistencies. When using deformation vector fields (DVFs) that exhibit inverse-inconsistency and are nontransitive, dose accumulation on a given image set via different image pathways will lead to different accumulated doses. The purpose of this study was to investigate the dosimetric effect of and propose a postprocessing solution to reduce inverse consistency and transitivity errors. Methods: Four MVCT images and four phases of a lung 4DCT, each with an associated calculated dose, were selected for analysis. DVFs between all four images in each data set were created using the Fast Symmetric Demons algorithm. Dose was accumulated on the fourth image in each set using DIR via two different image pathways. The two accumulated doses on the fourth image were compared. The inverse consistency and transitivity errors in the DVFs were then reduced. The dose accumulation was repeated using the processed DVFs, the results of which were compared with the accumulated dose from the original DVFs. To evaluate the influence of the postprocessing technique on DVF accuracy, the original and processed DVF accuracy was evaluated on the lung 4DCT data on which anatomical landmarks had been identified by an expert. Results: Dose accumulation to the same image via different image pathways resulted in two different accumulated dose results. After the inverse consistency errors were reduced, the difference between the accumulated doses diminished. The difference was further reduced after reducing the transitivity errors. The postprocessing technique had minimal effect on the accuracy of the DVF for the lung 4DCT images. Conclusions: This study shows that inverse consistency and transitivity errors in DIR have a significant dosimetric effect in dose accumulation; Depending on the image pathway taken

  18. The adaptive statistical iterative reconstruction-V technique for radiation dose reduction in abdominal CT: comparison with the adaptive statistical iterative reconstruction technique.

    PubMed

    Kwon, Heejin; Cho, Jinhan; Oh, Jongyeong; Kim, Dongwon; Cho, Junghyun; Kim, Sanghyun; Lee, Sangyun; Lee, Jihyun

    2015-10-01

    To investigate whether reduced radiation dose abdominal CT images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V) compromise the depiction of clinically competent features when compared with the currently used routine radiation dose CT images reconstructed with ASIR. 27 consecutive patients (mean body mass index: 23.55 kg m(-2) underwent CT of the abdomen at two time points. At the first time point, abdominal CT was scanned at 21.45 noise index levels of automatic current modulation at 120 kV. Images were reconstructed with 40% ASIR, the routine protocol of Dong-A University Hospital. At the second time point, follow-up scans were performed at 30 noise index levels. Images were reconstructed with filtered back projection (FBP), 40% ASIR, 30% ASIR-V, 50% ASIR-V and 70% ASIR-V for the reduced radiation dose. Both quantitative and qualitative analyses of image quality were conducted. The CT dose index was also recorded. At the follow-up study, the mean dose reduction relative to the currently used common radiation dose was 35.37% (range: 19-49%). The overall subjective image quality and diagnostic acceptability of the 50% ASIR-V scores at the reduced radiation dose were nearly identical to those recorded when using the initial routine-dose CT with 40% ASIR. Subjective ratings of the qualitative analysis revealed that of all reduced radiation dose CT series reconstructed, 30% ASIR-V and 50% ASIR-V were associated with higher image quality with lower noise and artefacts as well as good sharpness when compared with 40% ASIR and FBP. However, the sharpness score at 70% ASIR-V was considered to be worse than that at 40% ASIR. Objective image noise for 50% ASIR-V was 34.24% and 46.34% which was lower than 40% ASIR and FBP. Abdominal CT images reconstructed with ASIR-V facilitate radiation dose reductions of to 35% when compared with the ASIR. This study represents the first clinical research experiment to use ASIR-V, the newest version of

  19. Evaluation of dose reduction versus standard dosing for maintenance of remission in patients with spondyloarthritis and clinical remission with anti-TNF (REDES-TNF): study protocol for a randomized controlled trial.

    PubMed

    Pontes, Caridad; Gratacós, Jordi; Torres, Ferran; Avendaño, Cristina; Sanz, Jesús; Vallano, Antoni; Juanola, Xavier; de Miguel, Eugenio; Sanmartí, Raimon; Calvo, Gonzalo

    2015-08-20

    Dose reduction schedules of tumor necrosis factor antagonists (anti-TNF) as maintenance therapy in patients with spondyloarthritis are used empirically in clinical practice, despite the lack of clinical trials providing evidence for this practice. To address this issue the Spanish Society of Rheumatology (SER) and Spanish Society of Clinical Pharmacology (SEFC) designed a 3-year multicenter, randomized, open-label, controlled clinical trial (2 years for inclusion and 1 year of follow-up). The study is expected to include 190 patients with axial spondyloarthritis on stable maintenance treatment (≥4 months) with any anti-TNF agent at doses recommended in the summary of product characteristics. Patients will be randomized to either a dose reduction arm or maintenance of the dosing regimen as per the official labelling recommendations. Randomization will be stratified according to the anti-TNF agent received before study inclusion. Patient follow-up, visit schedule, and examinations will be maintained as per normal clinical practice recommendations according to SER guidelines. The study aims to test the hypothesis of noninferiority of the dose reduction strategy compared with standard treatment. The first patients were recruited in July 2012, and study completion is scheduled for the end of April 2015. The REDES-TNF study is a pragmatic clinical trial that aims to provide evidence to support a medical decision now made empirically. The study results may help inform clinical decisions relevant to both patients and healthcare decision makers. EudraCT 2011-005871-18 (21 December 2011).

  20. Radiation dose reduction for patients with extranodal NK/T-cell lymphoma with complete response after initial induction chemotherapy

    PubMed Central

    Wang, Liang; Bi, Xi-wen; Xia, Zhong-jun; Huang, Hui-qiang; Jiang, Wen-qi; Zhang, Yu-jing

    2016-01-01

    Previous studies have found that radiotherapy (RT) dose less than 50 Gy resulted in inferior outcomes for early stage extranodal NK/T-cell lymphoma (ENKTL). Nowadays, induction chemotherapy (CT) followed by RT consolidation is often used. For patients who get complete response (CR) after CT, whether RT dose can be safely reduced or not remains unknown. This retrospective study compared the survival outcomes between patients who received higher dose (>50 Gy) and lower dose (≤50 Gy) RT after CR was attained by CT. One hundred and forty four patients of early stage ENKTL got CR after induction CT and received RT consolidation. Thirty-one patients received lower dose RT (median 46 Gy, range, 36–50 Gy), and 113 patients received higher dose RT (median 56 Gy, range, 52–66 Gy). In univariate survival analysis, age >60, local tumor invasion, and non-asparaginase-based CT were associated with inferior progression-free survival (PFS) and overall survival (OS). However, there were no differences in PFS and OS between patients treated with higher and lower dose RT, which was confirmed in the multivariate survival analysis. Furthermore, reduced dose RT did not affect local control rate. Most common RT-related side effects were grade 1/2 mucositis and dermatitis, and the incidence rate of grade 3 mucositis or dermatitis was lower in patients treated with reduced dose RT (9.7% vs 15.0% for mucositis, and 6.5% vs 17.7% for dermatitis). In conclusion, this study found that RT dose could be safely reduced without compromising survival outcomes and further improved RT-related side effects. Prospective randomized controlled trials are warranted to validate our findings. PMID:27713641

  1. Efficacy of a dynamic collimator for overranging dose reduction in a second- and third-generation dual source CT scanner.

    PubMed

    Booij, Ronald; Dijkshoorn, Marcel L; van Straten, Marcel

    2017-09-01

    The purpose of this study was to assess the efficacy of the renewed dynamic collimator in a third-generation dual source CT (DSCT) scanner and to determine the improvements over the second-generation scanner. Collimator efficacy is defined as the percentage overranging dose in terms of dose-length product (DLP) that is blocked by the dynamic collimator relative to the total overranging dose in case of a static collimator. Efficacy was assessed at various pitch values and different scan lengths. The number of additional rotations due to overranging and effective scan length were calculated on the basis of reported scanning parameters. On the basis of these values, the efficacy of the collimator was calculated. The second-generation scanner showed decreased performance of the dynamic collimator at increasing pitch. Efficacy dropped to 10% at the highest pitch. For the third-generation scanner the efficacy remained above 50% at higher pitch. Noise was for some pitch values slightly higher at the edge of the imaged volume, indicating a reduced scan range to reduce the overranging dose. The improved dynamic collimator in the third-generation scanner blocks the overranging dose for more than 50% and is more capable of shielding radiation dose, especially in high pitch scan modes. • Overranging dose is to a large extent blocked by the dynamic collimator • Efficacy is strongly improved within the third-generation DSCT scanner • Reducing the number of additional rotations can reduce overranging with increased noise.

  2. Assessment of the dose reduction potential of a model-based iterative reconstruction algorithm using a task-based performance metrology

    SciTech Connect

    Samei, Ehsan; Richard, Samuel

    2015-01-15

    Purpose: Different computed tomography (CT) reconstruction techniques offer different image quality attributes of resolution and noise, challenging the ability to compare their dose reduction potential against each other. The purpose of this study was to evaluate and compare the task-based imaging performance of CT systems to enable the assessment of the dose performance of a model-based iterative reconstruction (MBIR) to that of an adaptive statistical iterative reconstruction (ASIR) and a filtered back projection (FBP) technique. Methods: The ACR CT phantom (model 464) was imaged across a wide range of mA setting on a 64-slice CT scanner (GE Discovery CT750 HD, Waukesha, WI). Based on previous work, the resolution was evaluated in terms of a task-based modulation transfer function (MTF) using a circular-edge technique and images from the contrast inserts located in the ACR phantom. Noise performance was assessed in terms of the noise-power spectrum (NPS) measured from the uniform section of the phantom. The task-based MTF and NPS were combined with a task function to yield a task-based estimate of imaging performance, the detectability index (d′). The detectability index was computed as a function of dose for two imaging tasks corresponding to the detection of a relatively small and a relatively large feature (1.5 and 25 mm, respectively). The performance of MBIR in terms of the d′ was compared with that of ASIR and FBP to assess its dose reduction potential. Results: Results indicated that MBIR exhibits a variability spatial resolution with respect to object contrast and noise while significantly reducing image noise. The NPS measurements for MBIR indicated a noise texture with a low-pass quality compared to the typical midpass noise found in FBP-based CT images. At comparable dose, the d′ for MBIR was higher than those of FBP and ASIR by at least 61% and 19% for the small feature and the large feature tasks, respectively. Compared to FBP and ASIR, MBIR

  3. [The reduction of the dose to the lung in whole-body irradiation with cobalt-60 gamma rays (author's transl)].

    PubMed

    Hochhäuser, E; Balk, O A

    1980-09-01

    In order to reduce the exposure of the lung and oesophagus during whole-body irradiation with cobalt-60 gamma rays the dose rate delivered to the lungs and the neck is diminished by means of a filter. Because of its special shape, sternum and columna vertebralis obtain the unreduced dose. The filter is constructed for irradiation in antero-posterior direction. A fixed position of the patient is not necessary.

  4. An investigation of kV CBCT image quality and dose reduction for volume-of-interest imaging using dynamic collimation

    SciTech Connect

    Parsons, David E-mail: james.robar@cdha.nshealth.ca; Robar, James L. E-mail: james.robar@cdha.nshealth.ca

    2015-09-15

    Purpose: The focus of this work was to investigate the improvements in image quality and dose reduction for volume-of-interest (VOI) kilovoltage-cone beam CT (CBCT) using dynamic collimation. Methods: A prototype iris aperture was used to track a VOI during a CBCT acquisition. The current aperture design is capable of 1D translation as a function of gantry angle and dynamic adjustment of the iris radius. The aperture occupies the location of the bow-tie filter on a Varian On-Board Imager system. CBCT and planar image quality were investigated as a function of aperture radius, while maintaining the same dose to the VOI, for a 20 cm diameter cylindrical water phantom with a 9 mm diameter bone insert centered on isocenter. Corresponding scatter-to-primary ratios (SPR) were determined at the detector plane with Monte Carlo simulation using EGSnrc. Dose distributions for various sizes VOI were modeled using a dynamic BEAMnrc library and DOSXYZnrc. The resulting VOI dose distributions were compared to full-field distributions. Results: SPR was reduced by a factor of 8.4 when decreasing iris diameter from 21.2 to 2.4 cm (at isocenter). Depending upon VOI location and size, dose was reduced to 16%–90% of the full-field value along the central axis plane and down to 4% along the axis of rotation, while maintaining the same dose to the VOI compared to full-field techniques. When maintaining constant dose to the VOI, this change in iris diameter corresponds to a factor increase of approximately 1.6 in image contrast and a factor decrease in image noise of approximately 1.2. This results in a measured gain in contrast-to-noise ratio by a factor of approximately 2.0. Conclusions: The presented VOI technique offers improved image quality for image-guided radiotherapy while sparing the surrounding volume of unnecessary dose compared to full-field techniques.

  5. Dose and volume reduction for normal lung using intensity-modulated radiotherapy for advanced-stage non-small-cell lung cancer.

    PubMed

    Murshed, Hasan; Liu, H Helen; Liao, Zhongxing; Barker, Jerry L; Wang, Xiaochun; Tucker, Susan L; Chandra, Anurag; Guerrero, Thomas; Stevens, Craig; Chang, Joe Y; Jeter, Melinda; Cox, James D; Komaki, Ritsuko; Mohan, Radhe; Change, Joe Y

    2004-03-15

    To investigate dosimetric improvements with respect to tumor-dose conformity and normal tissue sparing using intensity-modulated radiotherapy (IMRT) compared with three-dimensional conformal radiotherapy (3D-CRT) for advanced-stage non-small-cell lung cancer (NSCLC). Forty-one patients with Stage III-IV and recurrent NSCLC who previously underwent 3D-CRT were included. IMRT plans were designed to deliver 63 Gy to 95% of the planning target volume using nine equidistant coplanar 6-MV beams. Inverse planning was performed to minimize the volumes of normal lung, heart, esophagus, and spinal cord irradiated above their tolerance doses. Dose distributions and dosimetric indexes for the tumors and critical structures in both plans were computed and compared. Using IMRT, the median absolute reduction in the percentage of lung volume irradiated to >10 and >20 Gy was 7% and 10%, respectively. This corresponded to a decrease of >2 Gy in the total lung mean dose and of 10% in the risk of radiation pneumonitis. The volumes of the heart and esophagus irradiated to >40-50 Gy and normal thoracic tissue volume irradiated to >10-40 Gy were reduced using the IMRT plans. A marginal increase occurred in the spinal cord maximal dose and lung volume >5 Gy in the IMRT plans, which could be have resulted from the significant increase in monitor units and thus leakage dose in IMRT. IMRT planning significantly improved target coverage and reduced the volume of normal lung irradiated above low doses. The spread of low doses to normal tissues can be controlled in IMRT with appropriately selected planning parameters. The dosimetric benefits of IMRT for advanced-stage non-small-cell lung cancer must be evaluated further in clinical trials.

  6. Feasibility of Dose Reduction Using Novel Denoising Techniques for Low kV (80 kV) CT Enterography: Optimization and Validation

    PubMed Central

    Guimarães, Luís S; Fletcher, Joel G; Yu, Lifeng; Huprich, James E; Fidler, Jeff L.; Manduca, Armando; Ramirez-Giraldo, Juan Carlos; Holmes, David R.; McCollough, Cynthia H

    2010-01-01

    Rational and Objectives To optimize and validate projection space denoising (PSDN) strategies for application to 80 kV computed tomography (CT) data to achieve 50% dose reduction. Materials and Methods This retrospective HIPAA-compliant study had IRB approval. We utilized 80 kV image data (mean CTDIvol 7.9 mGy) obtained from dual-source dual-energy CTE exams in 42 patients. For each exam, nine 80 kV image datasets were reconstructed using PSDN (3 levels of intensity) ± image-based denoising and compared to commercial reconstruction kernels. For optimization, qualitative analysis selected optimal denoising strategies, with quantitative analysis measuring image contrast, noise and sharpness (FWHM bowel wall thickness, maximum CT number gradient). For validation, two radiologists examined image quality, comparing low-dose 80 kV optimally denoised images to full dose mixed kV images. Results PSDN algorithms generated the best 80 kV image quality (41/42 patients), while the commercial kernels produced the worst (39/42, p < 0.001). Overall 80 kV PSDN approaches resulted in higher contrast (mean 332 HU vs. 290 HU), slightly less noise (mean 20 HU vs. 26 HU), but slightly decreased images sharpness (relative bowel wall thickness, 1.069 vs. 1.000) compared to full-dose mixed kV images. Mean image quality scores for full-dose CTE images was 4.9 compared to 4.5 for optimally-denoised half-dose 80 kV CTE images, and 3.1 for non-denoised 80 kV CTE images (p<0.001). Conclusion Optimized denoising strategies improve the quality of 80 kV CT enterography images such that CT data obtained at 50% of routine dose levels approaches the image quality of full-dose exams. PMID:20832023

  7. A Monte Carlo study on quantifying the amount of dose reduction by shielding the superficial organs of an Iranian 11-year-old boy

    PubMed Central

    Akhlaghi, Parisa; Hoseinian-Azghadi, Elie; Miri-Hakimabad, Hashem; Rafat-Motavalli, Laleh

    2016-01-01

    A method for minimizing organ dose during computed tomography examinations is the use of shielding to protect superficial organs. There are some scientific reports that usage of shielding technique reduces the surface dose to patients with no appreciable loss in diagnostic quality. Therefore, in this Monte Carlo study based on the phantom of a 11-year-old Iranian boy, the effect of using an optimized shield on dose reduction to body organs was quantified. Based on the impact of shield on image quality, lead shields with thicknesses of 0.2 and 0.4 mm were considered for organs exposed directly and indirectly in the scan range, respectively. The results showed that there is 50%–62% reduction in amounts of dose for organs located fully or partly in the scan range at different tube voltages and modeling the true location of all organs in human anatomy, especially the ones located at the border of the scan, range affects the results up to 49%. PMID:28144117

  8. Dose Reduction in Contrast-Enhanced Cervical MR Angiography: Field Strength Dependency of Vascular Signal Intensity, Contrast Administration, and Arteriographic Quality.

    PubMed

    Dehkharghani, Seena; Qiu, Deqiang; Albin, Lauren S; Saindane, Amit M

    2015-06-01

    Cervical contrast-enhanced MR angiography (MRA) has proven accurate and superior to noncontrast alternatives. We proposed the systematic investigation of dose reduction in contrast-enhanced MRA, hypothesizing heightened tolerance at 3 T vs 1.5 T. Quantitative and qualitative features were compared between full-dose and 50%-reduced dose examinations at 1.5 T and 3 T. One hundred eight cervical contrast-enhanced MRA examinations were reviewed for qualitative and quantitative (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) features across four dose-field strength combinations: 1.5 T, 0.05 mmol/kg; 3 T, 0.05 mmol/kg; 1.5 T, 0.1 mmol/kg; and 3 T, 0.1 mmol/kg. Quantitative features were evaluated among the following segments: aortic arch, common carotid arteries, common carotid bifurcations, and cervical internal carotid arteries. A qualitative visual rating scale was applied for the same segments as well as to the vertebral arteries along their proximal (V1), intraforaminal (V2), and distal extraforaminal (V3) courses. Significant between-group differences were reported at p < 0.05. Qualitatively good arteriography was observed in all segments for all protocols. No significant qualitative differences between protocols were noted throughout evaluation of the anterior cervical circulation. Significant qualitative differences were observed only for V2 and V3 segments at half-dose 1.5-T compared with the remaining protocols (p < 0.05). No significant quantitative differences were present between full-dose and dose-reduced 3-T MRA in any segment. At 1.5 T, significant decrement in SNR and CNR at half-dose was present only within the cervical internal carotid artery. Dose reduction in cervical contrast-enhanced MRA is feasible at 3 T without significant compromise in arteriographic quality in most segments. Particularly at 3 T, arteriography is quantitatively and qualitatively robust and may be advisable in high-risk patients.

  9. Cone beam CT with zonal filters for simultaneous dose reduction, improved target contrast and automated set-up in radiotherapy.

    PubMed

    Moore, C J; Marchant, T E; Amer, A M

    2006-05-07

    Cone beam CT (CBCT) using a zonal filter is introduced. The aims are reduced concomitant imaging dose to the patient, simultaneous control of body scatter for improved image quality in the tumour target zone and preserved set-up detail for radiotherapy. Aluminium transmission diaphragms added to the CBCT x-ray tube of the Elekta Synergytrade mark linear accelerator produced an unattenuated beam for a central "target zone" and a partially attenuated beam for an outer "set-up zone". Imaging doses and contrast noise ratios (CNR) were measured in a test phantom for transmission diaphragms 12 and 24 mm thick, for 5 and 10 cm long target zones. The effect on automatic registration of zonal CBCT to conventional CT was assessed relative to full-field and lead-collimated images of an anthropomorphic phantom. Doses along the axis of rotation were reduced by up to 50% in both target and set-up zones, and weighted dose (two thirds surface dose plus one third central dose) was reduced by 10-20% for a 10 cm long target zone. CNR increased by up to 15% in zonally filtered CBCT images compared to full-field images. Automatic image registration remained as robust as that with full-field images and was superior to CBCT coned down using lead-collimation. Zonal CBCT significantly reduces imaging dose and is expected to benefit radiotherapy through improved target contrast, required to assess target coverage, and wide-field edge detail, needed for robust automatic measurement of patient set-up error.

  10. [Evaluation of a low dose imaging protocol on radiation exposure reduction in pediatric supraventricular tachycardia ablation procedure].

    PubMed

    Wang, F; Lu, Y; Yuan, C; Bai, J R; Yang, H S; Wu, L

    2017-04-02

    Objective: To evaluate the feasibility and efficiency of a low dose imaging protocol on reducing X-ray dose level in pediatric supraventricular tachycardia (SVT) ablation procedure. Method: Data were collected from 103 patients who underwent catheter ablation for SVT in Children's Hospital of Fudan University from January 2014 to October 2016 in terms of body weight, body surface area (BSA), SVT types, accessory pathway location, fluoroscopy time and the radiation dose (including AIR KERMA and dose area product) in a case observational study.The fluoroscopy protocols were operated at 36 nGy/frame and 10 frames/s (Standard group, n=47) from January 2014 to September 2015, 36 nGy/frame and 10 frames/s with removal of the grid (Grid-out group, n=24) from October 2015 to April 2016, as well as 23 nGy/frame and 4.0-7.5 frames/s without the grid (Grid-out plus low dose group, n=32) from May 2016 to October 2016, respectively.Comparisons among groups were performed by independent-sample t-test or one-way analysis of variance for normally distributed continuous variables, and χ(2) test for categorical variables. Result: The average body weight, BSA, fluoroscopy time and AIR KERMA of the three groups was (34±14) kg, (1.14±0.33) m(2,) (11±8) minutes and (12.97±12.43) mGy, respectively.No significant differences in body weight (F=2.55