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Sample records for additive dose method

  1. A mathematical approach to optimal selection of dose values in the additive dose method of ERP dosimetry

    SciTech Connect

    Hayes, R.B.; Haskell, E.H.; Kenner, G.H.

    1996-01-01

    Additive dose methods commonly used in electron paramagnetic resonance (EPR) dosimetry are time consuming and labor intensive. We have developed a mathematical approach for determining optimal spacing of applied doses and the number of spectra which should be taken at each dose level. Expected uncertainitites in the data points are assumed to be normally distributed with a fixed standard deviation and linearity of dose response is also assumed. The optimum spacing and number of points necessary for the minimal error can be estimated, as can the likely error in the resulting estimate. When low doses are being estimated for tooth enamel samples the optimal spacing is shown to be a concentration of points near the zero dose value with fewer spectra taken at a single high dose value within the range of known linearity. Optimization of the analytical process results in increased accuracy and sample throughput.

  2. A Four-step Approach for Evaluation of Dose Additivity

    EPA Science Inventory

    A four step approach was developed for evaluating toxicity data on a chemical mixture for consistency with dose addition. Following the concepts in the U.S. EPA mixture guidance (EPA 2000), toxicologic interaction for a defined mixture (all components known) is departure from a c...

  3. Detecting Departure From Additivity Along a Fixed-Ratio Mixture Ray With a Piecewise Model for Dose and Interaction Thresholds

    PubMed Central

    Gennings, Chris; Wagner, Elizabeth D.; Simmons, Jane Ellen; Plewa, Michael J.

    2010-01-01

    For mixtures of many chemicals, a ray design based on a relevant, fixed mixing ratio is useful for detecting departure from additivity. Methods for detecting departure involve modeling the response as a function of total dose along the ray. For mixtures with many components, the interaction may be dose dependent. Therefore, we have developed the use of a three-segment model containing both a dose threshold and an interaction threshold. Prior to the dose threshold, the response is that of background; between the dose threshold and the interaction threshold, an additive relationship exists; the model allows for departure from additivity beyond the interaction threshold. With such a model, we can conduct a hypothesis test of additivity, as well as a test for a region of additivity. The methods are illustrated with cytotoxicity data that arise when Chinese hamster ovary cells are exposed to a mixture of nine haloacetic acids. PMID:21359103

  4. Methods of calculating radiation absorbed dose.

    PubMed

    Wegst, A V

    1987-01-01

    The new tumoricidal radioactive agents being developed will require a careful estimate of radiation absorbed tumor and critical organ dose for each patient. Clinical methods will need to be developed using standard imaging or counting instruments to determine cumulated organ activities with tracer amounts before the therapeutic administration of the material. Standard MIRD dosimetry methods can then be applied.

  5. Dose additive effects of simvastatin and dipentyl phthalate on ...

    EPA Pesticide Factsheets

    Sex differentiation of the mammalian reproductive tract is a highly regulated process that is driven, in part, by fetal testosterone (T) production. In utero exposure to phthalate esters (PE) during sex differentiation can cause reproductive tract malformations in rats. PE alter the expression of genes associated with steroid synthesis/transport and cholesterol biosynthesis. Simvastatin (SMV) is a cholesterol-lowering drug that inhibits HMG-CoA reductase. As cholesterol is a precursor for steroid biosynthesis, we proposed that maternal exposure to SMV during the critical period of sex differentiation would lower fetal T and result in corresponding alterations in cholesterol- and androgenmediated gene expression. Timed pregnant SD rats were dosed orally with SMV from GD14-GD18. T production on GD18 was measured by RIA, and changes in gene expression in maternal and fetal tissues were assessed by quantitative rt-PCR. Circulating lipids were also measured in dams and fetuses. SMV lowered fetal T production, altered several genes involved in cholesterol biosynthesis in the maternal liver, and lowered lipids in the fetus but not in the dam. Unlike PE, SMV did not alter genes associated with sex differentiation. In a second experiment, dams were dosed with SMV, dipentyl phthalate (DPeP, a PE), or both. SMV and DPeP alone reduced fetal T production to 44.3 and 37.5% of control values, respectively, but the mixture reduced T production to 19.9% of control. These studies

  6. Bond additivity corrections for quantum chemistry methods

    SciTech Connect

    C. F. Melius; M. D. Allendorf

    1999-04-01

    In the 1980's, the authors developed a bond-additivity correction procedure for quantum chemical calculations called BAC-MP4, which has proven reliable in calculating the thermochemical properties of molecular species, including radicals as well as stable closed-shell species. New Bond Additivity Correction (BAC) methods have been developed for the G2 method, BAC-G2, as well as for a hybrid DFT/MP2 method, BAC-Hybrid. These BAC methods use a new form of BAC corrections, involving atomic, molecular, and bond-wise additive terms. These terms enable one to treat positive and negative ions as well as neutrals. The BAC-G2 method reduces errors in the G2 method due to nearest-neighbor bonds. The parameters within the BAC-G2 method only depend on atom types. Thus the BAC-G2 method can be used to determine the parameters needed by BAC methods involving lower levels of theory, such as BAC-Hybrid and BAC-MP4. The BAC-Hybrid method should scale well for large molecules. The BAC-Hybrid method uses the differences between the DFT and MP2 as an indicator of the method's accuracy, while the BAC-G2 method uses its internal methods (G1 and G2MP2) to provide an indicator of its accuracy. Indications of the average error as well as worst cases are provided for each of the BAC methods.

  7. A Novel Approach for Evaluating Carbamate Mixtures for Dose Additivity

    EPA Science Inventory

    Two mathematical approaches were used to test the hypothesis ofdose-addition for a binary and a seven-chemical mixture ofN-methyl carbamates, toxicologically similar chemicals that inhibit cholinesterase (ChE). In the more novel approach, mixture data were not included in the ana...

  8. Bond additivity corrections for quantum chemistry methods

    SciTech Connect

    Melius, C.F.; Allendorf, M.D.

    2000-03-23

    New bond additivity correction (BAC) methods have been developed for the G2 method, BAC-G2, as well as for a hybrid density functional theory (DFT) Moller-Plesset (MP)2 method, BAC-hybrid. These BAC methods use a new form of BAC corrections, involving atomic, molecular, and bond-wise additive terms. These terms enable one to treat positive and negative ions as well as neutrals. The BAC-G2 method reduces errors in the G2 method due to nearest-neighbor bonds. The parameters within the BAC-G2 method only depend on atom types. Thus the BAC-G2 method can be used to determine the parameters needed by BAC methods involving lower levels of theory, such as BAC-hybrid and BAC-MP4. The BAC-hybrid method is expected to scale well for large molecules. The BAC-hybrid method uses the differences between the DFT and MP2 predictions as an indication of the method's accuracy, whereas the BAC-G2 method uses its internal methods (G1 and G2MP2) to accomplish this. A statistical analysis of the error in each of the methods is presented on the basis of calculations performed for large sets (more than 120) of molecules.

  9. A method to evaluate dose errors introduced by dose mapping processes for mass conserving deformations

    SciTech Connect

    Yan, C.; Hugo, G.; Salguero, F. J.; Saleh-Sayah, N.; Weiss, E.; Sleeman, W. C.; Siebers, J. V.

    2012-04-15

    Purpose: To present a method to evaluate the dose mapping error introduced by the dose mapping process. In addition, apply the method to evaluate the dose mapping error introduced by the 4D dose calculation process implemented in a research version of commercial treatment planning system for a patient case. Methods: The average dose accumulated in a finite volume should be unchanged when the dose delivered to one anatomic instance of that volume is mapped to a different anatomic instance--provided that the tissue deformation between the anatomic instances is mass conserving. The average dose to a finite volume on image S is defined as d{sub S}=e{sub s}/m{sub S}, where e{sub S} is the energy deposited in the mass m{sub S} contained in the volume. Since mass and energy should be conserved, when d{sub S} is mapped to an image R(d{sub S{yields}R}=d{sub R}), the mean dose mapping error is defined as {Delta}d{sub m}=|d{sub R}-d{sub S}|=|e{sub R}/m{sub R}-e{sub S}/m{sub S}|, where the e{sub R} and e{sub S} are integral doses (energy deposited), and m{sub R} and m{sub S} are the masses within the region of interest (ROI) on image R and the corresponding ROI on image S, where R and S are the two anatomic instances from the same patient. Alternatively, application of simple differential propagation yields the differential dose mapping error, {Delta}d{sub d}=|({partial_derivative}d/{partial_derivative}e)*{Delta}e+({partial_derivative}d/{partial_derivative}m)*{Delta}m|=|((e{sub S}-e{sub R})/m{sub R})-((m{sub S}-m{sub R})/m{sub R}{sup 2})*e{sub R}|={alpha}|d{sub R}-d{sub S}| with {alpha}=m{sub S}/m{sub R}. A 4D treatment plan on a ten-phase 4D-CT lung patient is used to demonstrate the dose mapping error evaluations for a patient case, in which the accumulated dose, D{sub R}={Sigma}{sub S=0}{sup 9}d{sub S{yields}R}, and associated error values ({Delta}D{sub m} and {Delta}D{sub d}) are calculated for a uniformly spaced set of ROIs. Results: For the single sample patient dose

  10. Effusion plate using additive manufacturing methods

    DOEpatents

    Johnson, Thomas Edward; Keener, Christopher Paul; Ostebee, Heath Michael; Wegerif, Daniel Gerritt

    2016-04-12

    Additive manufacturing techniques may be utilized to construct effusion plates. Such additive manufacturing techniques may include defining a configuration for an effusion plate having one or more internal cooling channels. The manufacturing techniques may further include depositing a powder into a chamber, applying an energy source to the deposited powder, and consolidating the powder into a cross-sectional shape corresponding to the defined configuration. Such methods may be implemented to construct an effusion plate having one or more channels with a curved cross-sectional geometry.

  11. Effective dose of dental CBCT—a meta analysis of published data and additional data for nine CBCT units

    PubMed Central

    Timothy, R; Walker, C; Hunter, R; Benavides, E; Samuelson, D B; Scheske, M J

    2015-01-01

    Objectives: This article analyses dose measurement and effective dose estimation of dental CBCT examinations. Challenges to accurate calculation of dose are discussed and the use of dose–height product (DHP) as an alternative to dose–area product (DAP) is explored. Methods: The English literature on effective dose was reviewed. Data from these studies together with additional data for nine CBCT units were analysed. Descriptive statistics, ANOVA and paired analysis are used to characterize the data. Results: PubMed and EMBASE searches yielded 519 and 743 publications, respectively, which were reduced to 20 following review. Reported adult effective doses for any protocol ranged from 46 to 1073 µSv for large fields of view (FOVs), 9–560 µSv for medium FOVs and 5–652 µSv for small FOVs. Child effective doses from any protocol ranged from 13 to 769 µSv for large or medium FOVs and 7–521 µSv for small FOVs. Effective doses from standard or default exposure protocols were available for 167 adult and 52 child exposures. Mean adult effective doses grouped by FOV size were 212 µSv (large), 177 µSv (medium) and 84 µSv (small). Mean child doses were 175 µSv (combined large and medium) and 103 µSv (small). Large differences were seen between different CBCT units. Additional low-dose and high-definition protocols available for many units extend the range of doses. DHP was found to reduce average absolute error for calculation of dose by 45% in comparison with DAP. Conclusions: Large exposure ranges make CBCT doses difficult to generalize. Use of DHP as a metric for estimating effective dose warrants further investigation. PMID:25224586

  12. Toward an organ based dose prescription method for the improved accuracy of murine dose in orthovoltage x-ray irradiators

    SciTech Connect

    Belley, Matthew D.; Wang, Chu; Nguyen, Giao; Gunasingha, Rathnayaka; Chao, Nelson J.; Chen, Benny J.; Dewhirst, Mark W.; Yoshizumi, Terry T.

    2014-03-15

    Purpose: Accurate dosimetry is essential when irradiating mice to ensure that functional and molecular endpoints are well understood for the radiation dose delivered. Conventional methods of prescribing dose in mice involve the use of a single dose rate measurement and assume a uniform average dose throughout all organs of the entire mouse. Here, the authors report the individual average organ dose values for the irradiation of a 12, 23, and 33 g mouse on a 320 kVp x-ray irradiator and calculate the resulting error from using conventional dose prescription methods. Methods: Organ doses were simulated in the Geant4 application for tomographic emission toolkit using the MOBY mouse whole-body phantom. Dosimetry was performed for three beams utilizing filters A (1.65 mm Al), B (2.0 mm Al), and C (0.1 mm Cu + 2.5 mm Al), respectively. In addition, simulated x-ray spectra were validated with physical half-value layer measurements. Results: Average doses in soft-tissue organs were found to vary by as much as 23%–32% depending on the filter. Compared to filters A and B, filter C provided the hardest beam and had the lowest variation in soft-tissue average organ doses across all mouse sizes, with a difference of 23% for the median mouse size of 23 g. Conclusions: This work suggests a new dose prescription method in small animal dosimetry: it presents a departure from the conventional approach of assigninga single dose value for irradiation of mice to a more comprehensive approach of characterizing individual organ doses to minimize the error and uncertainty. In human radiation therapy, clinical treatment planning establishes the target dose as well as the dose distribution, however, this has generally not been done in small animal research. These results suggest that organ dose errors will be minimized by calibrating the dose rates for all filters, and using different dose rates for different organs.

  13. Supplier Selection Using Weighted Utility Additive Method

    NASA Astrophysics Data System (ADS)

    Karande, Prasad; Chakraborty, Shankar

    2015-10-01

    Supplier selection is a multi-criteria decision-making (MCDM) problem which mainly involves evaluating a number of available suppliers according to a set of common criteria for choosing the best one to meet the organizational needs. For any manufacturing or service organization, selecting the right upstream suppliers is a key success factor that will significantly reduce purchasing cost, increase downstream customer satisfaction and improve competitive ability. The past researchers have attempted to solve the supplier selection problem employing different MCDM techniques which involve active participation of the decision makers in the decision-making process. This paper deals with the application of weighted utility additive (WUTA) method for solving supplier selection problems. The WUTA method, an extension of utility additive approach, is based on ordinal regression and consists of building a piece-wise linear additive decision model from a preference structure using linear programming (LP). It adopts preference disaggregation principle and addresses the decision-making activities through operational models which need implicit preferences in the form of a preorder of reference alternatives or a subset of these alternatives present in the process. The preferential preorder provided by the decision maker is used as a restriction of a LP problem, which has its own objective function, minimization of the sum of the errors associated with the ranking of each alternative. Based on a given reference ranking of alternatives, one or more additive utility functions are derived. Using these utility functions, the weighted utilities for individual criterion values are combined into an overall weighted utility for a given alternative. It is observed that WUTA method, having a sound mathematical background, can provide accurate ranking to the candidate suppliers and choose the best one to fulfill the organizational requirements. Two real time examples are illustrated to prove

  14. Dose effect in the wood plastic composite formation in the presence of additives and co-additives

    NASA Astrophysics Data System (ADS)

    Khan, Mubarak A.; Ali, K. M. Idriss

    1994-10-01

    Wood plastic composite (WPC) formation was studied with simul wood and butylmethacrylate (BMA) at different compositions with swelling solvent methanol in the presence of a set of multifunctional acrylate monomer additives like N-vinyl Pyrrolidone (NVP), tripropylene glycol diacrylate (TPGDA) and trimethylol propane triacrylate (TMPTA) at a different doses between 1 and 3 Mrad using Co 60 gamma source. This was further investigated using another set of additives chosen from oligomers such as epoxy acrylate (EA), urethane acrylate (UA) and polyester acrylate (PEA). TMPTA yielded the highest polymer loading at relatively low dose (2 Mrad). Effect of co-additives like sulfuric acid (H + ions), copper sulphate (Cu 2+ ions) and urea was investigated in these series. Tensile strength (TS) of the composites were determined and the highest TS values were obtained with the composite produced in presence of urea.

  15. A Four Step Approach to Evaluate Mixtures for Consistency with Dose Addition

    EPA Science Inventory

    We developed a four step approach for evaluating chemical mixture data for consistency with dose addition for use in environmental health risk assessment. Following the concepts in the U.S. EPA mixture risk guidance (EPA 2000a,b), toxicological interaction for a defined mixture (...

  16. DOSE ADDITIVITY OF ATRAZINE AND BROMODICHLOROMETHANE IN CAUSING PREGNANCY LOSS IN F344 RATS

    EPA Science Inventory

    DOSE ADDITIVITY OF ATRAZINE AND BROMODICHLOROMETHANE IN CAUSING
    PREGNANCY LOSS IN F344 RATS.

    AUTHORS (ALL): Narotsky, Michael G1; Best, Deborah S1; Bielmeier, Susan R2; Cooper, Ralph L1
    SPONSOR NAME: James E Andrews

    INSTITUTIONS (ALL):
    1. Reproductive Toxi...

  17. A novel method of estimating effective dose from the point dose method: a case study—parathyroid CT scans

    NASA Astrophysics Data System (ADS)

    Januzis, Natalie; Nguyen, Giao; Hoang, Jenny K.; Lowry, Carolyn; Yoshizumi, Terry T.

    2015-02-01

    The purpose of this study was to validate a novel approach of applying a partial volume correction factor (PVCF) using a limited number of MOSFET detectors in the effective dose (E) calculation. The results of the proposed PVCF method were compared to the results from both the point dose (PD) method and a commercial CT dose estimation software (CT-Expo). To measure organ doses, an adult female anthropomorphic phantom was loaded with 20 MOSFET detectors and was scanned using the non-contrast and 2 phase contrast-enhanced parathyroid imaging protocols on a 64-slice multi-detector computed tomography scanner. E was computed by three methods: the PD method, the PVCF method, and the CT-Expo method. The E (in mSv) for the PD method, the PVCF method, and CT-Expo method was 2.6  ±  0.2, 1.3  ±  0.1, and 1.1 for the non-contrast scan, 21.9  ±  0.4, 13.9  ±  0.2, and 14.6 for the 1st phase of the contrast-enhanced scan, and 15.5  ±  0.3, 9.8  ±  0.1, and 10.4 for the 2nd phase of the contrast-enhanced scan, respectively. The E with the PD method differed from the PVCF method by 66.7% for the non-contrast scan, by 44.9% and by 45.5% respectively for the 1st and 2nd phases of the contrast-enhanced scan. The E with PVCF was comparable to the results from the CT-Expo method with percent differences of 15.8%, 5.0%, and 6.3% for the non-contrast scan and the 1st and 2nd phases of the contrast-enhanced scan, respectively. To conclude, the PVCF method estimated E within 16% difference as compared to 50-70% in the PD method. In addition, the results demonstrate that E can be estimated accurately from a limited number of detectors.

  18. A Four-Step and Four-Criteria Approach for Evaluating Evidence of Dose Addition in Chemical Mixture Toxicity

    EPA Science Inventory

    Dose addition is the most frequently-used component-based approach for predicting dose response for a mixture of toxicologically-similar chemicals and for statistical evaluation of whether the mixture response is consistent with dose additivity and therefore predictable from the ...

  19. Assessment of diurnal systemic dose of agrochemicals in regulatory toxicity testing--an integrated approach without additional animal use.

    PubMed

    Saghir, Shakil A; Bartels, Michael J; Rick, David L; McCoy, Alene T; Rasoulpour, Reza J; Ellis-Hutchings, Robert G; Sue Marty, M; Terry, Claire; Bailey, Jason P; Billington, Richard; Bus, James S

    2012-07-01

    Integrated toxicokinetics (TK) data provide information on the rate, extent and duration of systemic exposure across doses, species, strains, gender, and life stages within a toxicology program. While routine for pharmaceuticals, TK assessments of non-pharmaceuticals are still relatively rare, and have never before been included in a full range of guideline studies for a new agrochemical. In order to better understand the relationship between diurnal systemic dose (AUC(24h)) and toxicity of agrochemicals, TK analyses in the study animals is now included in all short- (excluding acute), medium- and long-term guideline mammalian toxicity studies including reproduction/developmental tests. This paper describes a detailed procedure for the implementation of TK in short-, medium- and long-term regulatory toxicity studies, without the use of satellite animals, conducted on three agrochemicals (X11422208, 2,4-D and X574175). In these studies, kinetically-derived maximum doses (KMD) from short-term studies instead of, or along with, maximum tolerated doses (MTD) were used for the selection of the high dose in subsequent longer-term studies. In addition to leveraging TK data to guide dose level selection, the integrated program was also used to select the most appropriate method of oral administration (i.e., gavage versus dietary) of test materials for rat and rabbit developmental toxicity studies. The integrated TK data obtained across toxicity studies (without the use of additional/satellite animals) provided data critical to understanding differences in response across doses, species, strains, sexes, and life stages. Such data should also be useful in mode of action studies and to improve human risk assessments.

  20. Simple methods for the estimation of dose distributions, organ doses and energy imparted in paediatric radiology.

    PubMed

    Almén, A; Nilsson, M

    1996-07-01

    The energy imparted and the effective dose can both be used to describe the risk to the patient in diagnostic radiology. Simple methods must be employed to determine these quantities in clinical situations. Methods using measured relative depth-dose distributions are presented and evaluated here. Measurements of depth-dose distributions for x-ray beams were performed with an ionization chamber, a diode and a number of TL dosimeters. The energy imparted was calculated from measurements with both phantoms and patients. The method of calculating the mean absorbed dose to organs was applied to pelvis and lumbar spine examinations. TL dosimeters were found to be an appropriate detector for measuring depth-dose distributions. When calculating the energy imparted the entrance beam area must be accurately known. The mean absorbed dose to organs can be derived from measured relative depth-dose curves if accurate information on entrance beam position and area is available for the particular examination technique used. The advantage of these methods is that the dose distribution is measured for the photon beam used for the examination of the patients.

  1. "The Dose Makes the Poison": Informing Consumers About the Scientific Risk Assessment of Food Additives.

    PubMed

    Bearth, Angela; Cousin, Marie-Eve; Siegrist, Michael

    2016-01-01

    Intensive risk assessment is required before the approval of food additives. During this process, based on the toxicological principle of "the dose makes the poison,ˮ maximum usage doses are assessed. However, most consumers are not aware of these efforts to ensure the safety of food additives and are therefore sceptical, even though food additives bring certain benefits to consumers. This study investigated the effect of a short video, which explains the scientific risk assessment and regulation of food additives, on consumers' perceptions and acceptance of food additives. The primary goal of this study was to inform consumers and enable them to construct their own risk-benefit assessment and make informed decisions about food additives. The secondary goal was to investigate whether people have different perceptions of food additives of artificial (i.e., aspartame) or natural origin (i.e., steviolglycoside). To attain these research goals, an online experiment was conducted on 185 Swiss consumers. Participants were randomly assigned to either the experimental group, which was shown a video about the scientific risk assessment of food additives, or the control group, which was shown a video about a topic irrelevant to the study. After watching the video, the respondents knew significantly more, expressed more positive thoughts and feelings, had less risk perception, and more acceptance than prior to watching the video. Thus, it appears that informing consumers about complex food safety topics, such as the scientific risk assessment of food additives, is possible, and using a carefully developed information video is a successful strategy for informing consumers.

  2. Complexity of Monte Carlo and deterministic dose-calculation methods.

    PubMed

    Börgers, C

    1998-03-01

    Grid-based deterministic dose-calculation methods for radiotherapy planning require the use of six-dimensional phase space grids. Because of the large number of phase space dimensions, a growing number of medical physicists appear to believe that grid-based deterministic dose-calculation methods are not competitive with Monte Carlo methods. We argue that this conclusion may be premature. Our results do suggest, however, that finite difference or finite element schemes with orders of accuracy greater than one will probably be needed if such methods are to compete well with Monte Carlo methods for dose calculations.

  3. The Addition of Low-dose Thalidomide to Bortezomib and Dexamethasone for Refractory Multiple Myeloma

    PubMed Central

    Hashimoto, Shigeo; Kuroha, Takashi; Yano, Toshio; Sato, Naoko; Furukawa, Tatsuo

    2016-01-01

    Five cases were treated by adding daily low-dose thalidomide (50 mg) to bortezomib and dexamethasone therapy for refractory multiple myeloma. This therapy was effective in four cases, with an improvement of bone pain and regression of M-protein. One case was treated with cyclophosphamide, thalidomide, and dexamethasone, adding bortezomib after starting the three-drug combination therapy. This patient has remained in a stable disease state since the beginning of this therapy. Regarding the other four cases, a partial response and a prolonged survival for approximately one year were noted. Peripheral neuropathy did not increase after thalidomide addition. Adding low-dose thalidomide may safely improve the responses for multiple myeloma refractory to bortezomib and dexamethasone. PMID:27746443

  4. The Addition of Low-dose Thalidomide to Bortezomib and Dexamethasone for Refractory Multiple Myeloma.

    PubMed

    Hashimoto, Shigeo; Kuroha, Takashi; Yano, Toshio; Sato, Naoko; Furukawa, Tatsuo

    Five cases were treated by adding daily low-dose thalidomide (50 mg) to bortezomib and dexamethasone therapy for refractory multiple myeloma. This therapy was effective in four cases, with an improvement of bone pain and regression of M-protein. One case was treated with cyclophosphamide, thalidomide, and dexamethasone, adding bortezomib after starting the three-drug combination therapy. This patient has remained in a stable disease state since the beginning of this therapy. Regarding the other four cases, a partial response and a prolonged survival for approximately one year were noted. Peripheral neuropathy did not increase after thalidomide addition. Adding low-dose thalidomide may safely improve the responses for multiple myeloma refractory to bortezomib and dexamethasone.

  5. Patient-specific dose calculation methods for high-dose-rate iridium-192 brachytherapy

    NASA Astrophysics Data System (ADS)

    Poon, Emily S.

    In high-dose-rate 192Ir brachytherapy, the radiation dose received by the patient is calculated according to the AAPM Task Group 43 (TG-43) formalism. This table-based dose superposition method uses dosimetry parameters derived with the radioactive 192Ir source centered in a water phantom. It neglects the dose perturbations caused by inhomogeneities, such as the patient anatomy, applicators, shielding, and radiographic contrast solution. In this work, we evaluated the dosimetric characteristics of a shielded rectal applicator with an endocavitary balloon injected with contrast solution. The dose distributions around this applicator were calculated by the GEANT4 Monte Carlo (MC) code and measured by ionization chamber and GAFCHROMIC EBT film. A patient-specific dose calculation study was then carried out for 40 rectal treatment plans. The PTRAN_CT MC code was used to calculate the dose based on computed tomography (CT) images. This study involved the development of BrachyGUI, an integrated treatment planning tool that can process DICOM-RT data and create PTRAN_CT input initialization files. BrachyGUI also comes with dose calculation and evaluation capabilities. We proposed a novel scatter correction method to account for the reduction in backscatter radiation near tissue-air interfaces. The first step requires calculating the doses contributed by primary and scattered photons separately, assuming a full scatter environment. The scatter dose in the patient is subsequently adjusted using a factor derived by MC calculations, which depends on the distances between the point of interest, the 192Ir source, and the body contour. The method was validated for multicatheter breast brachytherapy, in which the target and skin doses for 18 patient plans agreed with PTRAN_CT calculations better than 1%. Finally, we developed a CT-based analytical dose calculation method. It corrects for the photon attenuation and scatter based upon the radiological paths determined by ray tracing

  6. TESTING FOR ADDITIVITY IN THE LOW DOSE REGION OF AN ENVIRONMENTALLY RELEVANT MIXTURE OF 18 OLYHALOGENATED AROMATIC HYDROCARBONS.

    EPA Science Inventory

    A common default assumption in risk assessment of chemical mixtures is that the chemicals combine additively in the low dose region. Under additivity, with information from single chemical dose-response data, the risk associated with the mixture can be estimated. The objective ...

  7. Dose calculation for electron therapy using an improved LBR method

    SciTech Connect

    Gebreamlak, Wondesen T.; Alkhatib, Hassaan A.; Tedeschi, David J.

    2013-07-15

    Purpose: To calculate the percentage depth dose (PDD) of any irregularly shaped electron beam using a modified lateral build-up ratio (LBR) method.Methods: Percentage depth dose curves were measured using 6, 9, 12, and 15 MeV electron beam energies for applicator cone sizes of 6 Multiplication-Sign 6, 10 Multiplication-Sign 10, 14 Multiplication-Sign 14, and 20 Multiplication-Sign 20 cm{sup 2}. Circular cutouts for each cone were prepared from 2.0 cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared.Results: The LBR for each circular cutout was calculated from the measured PDD curve using the open field of the 14 Multiplication-Sign 14 cm{sup 2} cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter [{sigma}{sub R}(z)] of the electron shower was calculated. Unlike the commonly accepted assumption that {sigma}{sub R}(z) is independent of cutout size, it is shown that its value increases linearly with circular cutout size (R). Using this characteristic of the lateral spread parameter, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves.Conclusions: In this research, it is shown that the lateral spread parameter {sigma}{sub R}(z) increases with cutout size. For radii of circular cutout sizes up to the equilibrium range of the electron beam, the increase of {sigma}{sub R}(z) with the cutout size is linear. The percentage difference of the calculated PDD curve from the measured PDD data for irregularly shaped cutouts was under 1.0% in the region between the surface and therapeutic range of the electron beam. Similar results were obtained for four electron beam energies (6, 9, 12, and 15 MeV)

  8. Radiation dose enhancement in skin therapy with nanoparticle addition: A Monte Carlo study on kilovoltage photon and megavoltage electron beams

    PubMed Central

    Zheng, Xiao J; Chow, James C L

    2017-01-01

    AIM To investigated the dose enhancement due to the incorporation of nanoparticles in skin therapy using the kilovoltage (kV) photon and megavoltage (MV) electron beams. Monte Carlo simulations were used to predict the dose enhancement when different types and concentrations of nanoparticles were added to skin target layers of varying thickness. METHODS Clinical kV photon beams (105 and 220 kVp) and MV electron beams (4 and 6 MeV), produced by a Gulmay D3225 orthovoltage unit and a Varian 21 EX linear accelerator, were simulated using the EGSnrc Monte Carlo code. Doses at skin target layers with thicknesses ranging from 0.5 to 5 mm for the photon beams and 0.5 to 10 mm for the electron beams were determined. The skin target layer was added with the Au, Pt, I, Ag and Fe2O3 nanoparticles with concentrations ranging from 3 to 40 mg/mL. The dose enhancement ratio (DER), defined as the dose at the target layer with nanoparticle addition divided by the dose at the layer without nanoparticle addition, was calculated for each nanoparticle type, nanoparticle concentration and target layer thickness. RESULTS It was found that among all nanoparticles, Au had the highest DER (5.2-6.3) when irradiated with kV photon beams. Dependence of the DER on the target layer thickness was not significant for the 220 kVp photon beam but it was for 105 kVp beam for Au nanoparticle concentrations higher than 18 mg/mL. For other nanoparticles, the DER was dependent on the atomic number of the nanoparticle and energy spectrum of the photon beams. All nanoparticles showed an increase of DER with nanoparticle concentration during the photon beam irradiations regardless of thickness. For electron beams, the Au nanoparticles were found to have the highest DER (1.01-1.08) when the beam energy was equal to 4 MeV, but this was drastically lower than the DER values found using photon beams. The DER was also found affected by the depth of maximum dose of the electron beam and target thickness. For

  9. METHOD OF OBTAINING AN ADDITIVE FOR LUBRICATING OILS,

    DTIC Science & Technology

    The method of obtaining an additive to lubricating oils , consisting of treating boron trifluoride with alkylphenol and alkylamine, is known. In this...case, (aminotrifluoralkyl)phenoxyborate is obtained which may be used as an antiwear additive for lubricating oils . The proposed method differs from

  10. Size-specific dose estimate (SSDE) provides a simple method to calculate organ dose for pediatric CT examinations

    SciTech Connect

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

    2014-07-15

    Purpose: To investigate the correlation of size-specific dose estimate (SSDE) with absorbed organ dose, and to develop a simple methodology for estimating patient organ dose in a pediatric population (5–55 kg). Methods: Four physical anthropomorphic phantoms representing a range of pediatric body habitus were scanned with metal oxide semiconductor field effect transistor (MOSFET) dosimeters placed at 23 organ locations to determine absolute organ dose. Phantom absolute organ dose was divided by phantom SSDE to determine correlation between organ dose and SSDE. Organ dose correlation factors (CF{sub SSDE}{sup organ}) were then multiplied by patient-specific SSDE to estimate patient organ dose. The CF{sub SSDE}{sup organ} were used to retrospectively estimate individual organ doses from 352 chest and 241 abdominopelvic pediatric CT examinations, where mean patient weight was 22 kg ± 15 (range 5–55 kg), and mean patient age was 6 yrs ± 5 (range 4 months to 23 yrs). Patient organ dose estimates were compared to published pediatric Monte Carlo study results. Results: Phantom effective diameters were matched with patient population effective diameters to within 4 cm; thus, showing appropriate scalability of the phantoms across the entire pediatric population in this study. IndividualCF{sub SSDE}{sup organ} were determined for a total of 23 organs in the chest and abdominopelvic region across nine weight subcategories. For organs fully covered by the scan volume, correlation in the chest (average 1.1; range 0.7–1.4) and abdominopelvic region (average 0.9; range 0.7–1.3) was near unity. For organ/tissue that extended beyond the scan volume (i.e., skin, bone marrow, and bone surface), correlation was determined to be poor (average 0.3; range: 0.1–0.4) for both the chest and abdominopelvic regions, respectively. A means to estimate patient organ dose was demonstrated. Calculated patient organ dose, using patient SSDE and CF{sub SSDE}{sup organ}, was compared to

  11. LETTER TO THE EDITOR: Enhancement of neutron radiation dose by the addition of sulphur-33 atoms

    NASA Astrophysics Data System (ADS)

    Porras, I.

    2008-04-01

    The use of neutrons in radiotherapy allows the possibility of producing nuclear reactions in a specific target inserted in the medium. 10B is being used to induce reactions (n, α), a technique called boron neutron capture therapy. I have studied the possibility of inducing a similar reaction using the nucleus of 33S, for which the reaction cross section presents resonances for keV neutrons, the highest peak occurring at 13.5 keV. Here shown, by means of Monte Carlo simulation of point-like sources of neutrons in this energy range, is an enhancement effect on the absorbed dose in water by the addition of 33S atoms. In addition to this, as the range of the alpha particle is of the order of a mammalian cell size, the energy deposition via this reaction results mainly inside the cells adjacent to the interaction site. The main conclusion of the present work is that the insertion of these sulphur atoms in tumoral cells would enhance the effect of neutron irradiation in the keV range.

  12. Testing for Additivity at Select Mixture Groups of Interest Based on Statistical Equivalence Testing Methods

    SciTech Connect

    Stork, LeAnna M.; Gennings, Chris; Carchman, Richard; Carter, Jr., Walter H.; Pounds, Joel G.; Mumtaz, Moiz

    2006-12-01

    Several assumptions, defined and undefined, are used in the toxicity assessment of chemical mixtures. In scientific practice mixture components in the low-dose region, particularly subthreshold doses, are often assumed to behave additively (i.e., zero interaction) based on heuristic arguments. This assumption has important implications in the practice of risk assessment, but has not been experimentally tested. We have developed methodology to test for additivity in the sense of Berenbaum (Advances in Cancer Research, 1981), based on the statistical equivalence testing literature where the null hypothesis of interaction is rejected for the alternative hypothesis of additivity when data support the claim. The implication of this approach is that conclusions of additivity are made with a false positive rate controlled by the experimenter. The claim of additivity is based on prespecified additivity margins, which are chosen using expert biological judgment such that small deviations from additivity, which are not considered to be biologically important, are not statistically significant. This approach is in contrast to the usual hypothesis-testing framework that assumes additivity in the null hypothesis and rejects when there is significant evidence of interaction. In this scenario, failure to reject may be due to lack of statistical power making the claim of additivity problematic. The proposed method is illustrated in a mixture of five organophosphorus pesticides that were experimentally evaluated alone and at relevant mixing ratios. Motor activity was assessed in adult male rats following acute exposure. Four low-dose mixture groups were evaluated. Evidence of additivity is found in three of the four low-dose mixture groups.The proposed method tests for additivity of the whole mixture and does not take into account subset interactions (e.g., synergistic, antagonistic) that may have occurred and cancelled each other out.

  13. Addition of Montelukast to Low-Dose Inhaled Corticosteroid Leads to Fewer Exacerbations in Older Patients Than Medium-Dose Inhaled Corticosteroid Monotherapy

    PubMed Central

    Ye, Young-Min; Kim, Sang-Ha; Hur, Gyu-Young; Kim, Joo-Hee; Park, Jung-Won; Shim, Jae Jeong; Jung, Ki-Suck; Lee, Hyun-Young

    2015-01-01

    Purpose There have been few reports regarding the efficacy of antiasthmatics in older patients. To compare the efficacy of the addition of montelukast to low-dose inhaled budesonide (MON-400BUD) versus increasing the dose of inhaled steroid (800BUD) on asthma control in older asthmatics. Methods A randomized, open-label, parallel-designed trial was conducted for 12 weeks. The primary endpoint was the rate of patients who reached "well-controlled asthma status" after the 12-week treatment period. Additionally, asthma exacerbations, sputum inflammatory cells, asthma control test (ACT) and physical functioning scale (PFS), and adverse reactions were monitored. Results Twenty-four (36.9%) and 22 (34.9%) subjects in the MON-400BUD (n=65) and 800BUD (n=63) groups had well-controlled asthma at the end of the study, respectively. The numbers of asthma exacerbations requiring oral corticosteroid treatment (20 vs 9, respectively, P=0.036) and the development of sore throat (22 vs 11, respectively, P=0.045) were significantly higher in the 800BUD group than in the MON-400BUD group. Body mass index and changes in ACT, FEV1%, 6-min walk distance and PFS from baseline were all significant determinants for distinguishing subjects with well-controlled and partly controlled asthma from those with uncontrolled asthma (P<0.05) at the end of the study. Conclusions The efficacy of 12-week treatment with MON-400BUD in older asthmatics was comparable to that of 800BUD on asthma control but associated with reduced frequency of asthma exacerbations requiring oral steroids and sore throat events. Changes in ACT and PFS can be useful predictors of asthma control status in older patients. PMID:26122504

  14. Calculating the peak skin dose resulting from fluoroscopically guided interventions. Part I: Methods.

    PubMed

    Jones, A Kyle; Pasciak, Alexander S

    2011-11-15

    While direct measurement of the peak skin dose resulting from a fluoroscopically-guided procedure is possible, the decision must be made a priori at additional cost and time. It is most often the case that the need for accurate knowledge of the peak skin dose is realized only after a procedure has been completed, or after a suspected reaction has been discovered. Part I of this review article discusses methods for calculating the peak skin dose across a range of clinical scenarios. In some cases, a wealth of data are available, while in other cases few data are available and additional data must be measured in order to estimate the peak skin dose. Data may be gathered from a dose report, the DICOM headers of images, or from staff and physician interviews. After data are gathered, specific steps must be followed to convert dose metrics, such as the reference point air kerma (K(a,r)) or the kerma area product (KAP), into peak skin dose. These steps require knowledge of other related factors, such as the f-factor and the backscatter factor, tables of which are provided in this manuscript. Sources of error and the impact of these errors on the accuracy of the final estimate of the peak skin dose are discussed.

  15. A molecular fraction method for measuring personnel radiation doses

    NASA Astrophysics Data System (ADS)

    Fadel, M. A.; Khalil, W. A.; Krodja, R. P.; Sheta, N.; Abd El-Baset, M. S.

    1987-02-01

    This work represents a development in fast and albedo neutron and gamma ray dosimetry, using cellulose nitrate, as a tissue equivalent material, in which radiation damage was registered. The changes in molecular fractions of the polymer were measured after irradiation with neutron fluences from a 252Cf source in the range 10 5-10 10 n/cm 2 and gamma doses in the range 10 -4-10 -1 Gy through the use of gel filtration chromatography. Effects of irradiation on phantom, phantom to dosimeter distance, phantom thickness and storage at extreme environmental conditions were studied on the detector response and readout. The results showed that main chain scission followed by formation of new molecular configurations is the predominant effect of radiation on the polymer. The method enables measurements of neutron fluences and gamma doses in mixed radiation fields. Empirical formulae for calculating the absorbed dose from the measured changes in molecular fraction intensities are given.

  16. Comparison of dose calculation methods for brachytherapy of intraocular tumors

    SciTech Connect

    Rivard, Mark J.; Chiu-Tsao, Sou-Tung; Finger, Paul T.; Meigooni, Ali S.; Melhus, Christopher S.; Mourtada, Firas; Napolitano, Mary E.; Rogers, D. W. O.; Thomson, Rowan M.; Nath, Ravinder

    2011-01-15

    Purpose: To investigate dosimetric differences among several clinical treatment planning systems (TPS) and Monte Carlo (MC) codes for brachytherapy of intraocular tumors using {sup 125}I or {sup 103}Pd plaques, and to evaluate the impact on the prescription dose of the adoption of MC codes and certain versions of a TPS (Plaque Simulator with optional modules). Methods: Three clinical brachytherapy TPS capable of intraocular brachytherapy treatment planning and two MC codes were compared. The TPS investigated were Pinnacle v8.0dp1, BrachyVision v8.1, and Plaque Simulator v5.3.9, all of which use the AAPM TG-43 formalism in water. The Plaque Simulator software can also handle some correction factors from MC simulations. The MC codes used are MCNP5 v1.40 and BrachyDose/EGSnrc. Using these TPS and MC codes, three types of calculations were performed: homogeneous medium with point sources (for the TPS only, using the 1D TG-43 dose calculation formalism); homogeneous medium with line sources (TPS with 2D TG-43 dose calculation formalism and MC codes); and plaque heterogeneity-corrected line sources (Plaque Simulator with modified 2D TG-43 dose calculation formalism and MC codes). Comparisons were made of doses calculated at points-of-interest on the plaque central-axis and at off-axis points of clinical interest within a standardized model of the right eye. Results: For the homogeneous water medium case, agreement was within {approx}2% for the point- and line-source models when comparing between TPS and between TPS and MC codes, respectively. For the heterogeneous medium case, dose differences (as calculated using the MC codes and Plaque Simulator) differ by up to 37% on the central-axis in comparison to the homogeneous water calculations. A prescription dose of 85 Gy at 5 mm depth based on calculations in a homogeneous medium delivers 76 Gy and 67 Gy for specific {sup 125}I and {sup 103}Pd sources, respectively, when accounting for COMS-plaque heterogeneities. For off

  17. Optimal Multicomponent Analysis Using the Generalized Standard Addition Method.

    ERIC Educational Resources Information Center

    Raymond, Margaret; And Others

    1983-01-01

    Describes an experiment on the simultaneous determination of chromium and magnesium by spectophotometry modified to include the Generalized Standard Addition Method computer program, a multivariate calibration method that provides optimal multicomponent analysis in the presence of interference and matrix effects. Provides instructions for…

  18. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  19. Dose reconstruction for intensity-modulated radiation therapy using a non-iterative method and portal dose image

    NASA Astrophysics Data System (ADS)

    Yeo, Inhwan Jason; Jung, Jae Won; Chew, Meng; Kim, Jong Oh; Wang, Brian; Di Biase, Steven; Zhu, Yunping; Lee, Dohyung

    2009-09-01

    A straightforward and accurate method was developed to verify the delivery of intensity-modulated radiation therapy (IMRT) and to reconstruct the dose in a patient. The method is based on a computational algorithm that linearly describes the physical relationship between beamlets and dose-scoring voxels in a patient and the dose image from an electronic portal imaging device (EPID). The relationship is expressed in the form of dose response functions (responses) that are quantified using Monte Carlo (MC) particle transport techniques. From the dose information measured by the EPID the received patient dose is reconstructed by inversely solving the algorithm. The unique and novel non-iterative feature of this algorithm sets it apart from many existing dose reconstruction methods in the literature. This study presents the algorithm in detail and validates it experimentally for open and IMRT fields. Responses were first calculated for each beamlet of the selected fields by MC simulation. In-phantom and exit film dosimetry were performed on a flat phantom. Using the calculated responses and the algorithm, the exit film dose was used to inversely reconstruct the in-phantom dose, which was then compared with the measured in-phantom dose. The dose comparison in the phantom for all irradiated fields showed a pass rate of higher than 90% dose points given the criteria of dose difference of 3% and distance to agreement of 3 mm.

  20. Optimizing CT radiation dose based on patient size and image quality: the size-specific dose estimate method.

    PubMed

    Larson, David B

    2014-10-01

    The principle of ALARA (dose as low as reasonably achievable) calls for dose optimization rather than dose reduction, per se. Optimization of CT radiation dose is accomplished by producing images of acceptable diagnostic image quality using the lowest dose method available. Because it is image quality that constrains the dose, CT dose optimization is primarily a problem of image quality rather than radiation dose. Therefore, the primary focus in CT radiation dose optimization should be on image quality. However, no reliable direct measure of image quality has been developed for routine clinical practice. Until such measures become available, size-specific dose estimates (SSDE) can be used as a reasonable image-quality estimate. The SSDE method of radiation dose optimization for CT abdomen and pelvis consists of plotting SSDE for a sample of examinations as a function of patient size, establishing an SSDE threshold curve based on radiologists' assessment of image quality, and modifying protocols to consistently produce doses that are slightly above the threshold SSDE curve. Challenges in operationalizing CT radiation dose optimization include data gathering and monitoring, managing the complexities of the numerous protocols, scanners and operators, and understanding the relationship of the automated tube current modulation (ATCM) parameters to image quality. Because CT manufacturers currently maintain their ATCM algorithms as secret for proprietary reasons, prospective modeling of SSDE for patient populations is not possible without reverse engineering the ATCM algorithm and, hence, optimization by this method requires a trial-and-error approach.

  1. Radiological environmental dose assessment methods and compliance dose results for 2015 operations at the Savannah River Site

    SciTech Connect

    Jannik, G. T.; Dixon, K. L.

    2016-09-01

    This report presents the environmental dose assessment methods and the estimated potential doses to the offsite public from 2015 Savannah River Site (SRS) atmospheric and liquid radioactive releases. Also documented are potential doses from special-case exposure scenarios - such as the consumption of deer meat, fish, and goat milk.

  2. Additive manufacturing method for SRF components of various geometries

    SciTech Connect

    Rimmer, Robert; Frigola, Pedro E; Murokh, Alex Y

    2015-05-05

    An additive manufacturing method for forming nearly monolithic SRF niobium cavities and end group components of arbitrary shape with features such as optimized wall thickness and integral stiffeners, greatly reducing the cost and technical variability of conventional cavity construction. The additive manufacturing method for forming an SRF cavity, includes atomizing niobium to form a niobium powder, feeding the niobium powder into an electron beam melter under a vacuum, melting the niobium powder under a vacuum in the electron beam melter to form an SRF cavity; and polishing the inside surface of the SRF cavity.

  3. Method for preparing dosimeter for measuring skin dose

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1982-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with neutron-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  4. 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.

  5. 10 CFR 2.705 - Discovery-additional methods.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Discovery-additional methods. 2.705 Section 2.705 Energy NUCLEAR REGULATORY COMMISSION RULES OF PRACTICE FOR DOMESTIC LICENSING PROCEEDINGS AND ISSUANCE OF ORDERS... 147 and 181 of the Atomic Energy Act of 1954, as amended, the presiding officer may issue an...

  6. 10 CFR 2.705 - Discovery-additional methods.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Discovery-additional methods. 2.705 Section 2.705 Energy NUCLEAR REGULATORY COMMISSION AGENCY RULES OF PRACTICE AND PROCEDURE Rules for Formal Adjudications § 2... 147 and 181 of the Atomic Energy Act of 1954, as amended, the presiding officer may issue an...

  7. 10 CFR 2.705 - Discovery-additional methods.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Discovery-additional methods. 2.705 Section 2.705 Energy NUCLEAR REGULATORY COMMISSION RULES OF PRACTICE FOR DOMESTIC LICENSING PROCEEDINGS AND ISSUANCE OF ORDERS... 147 and 181 of the Atomic Energy Act of 1954, as amended, the presiding officer may issue an...

  8. 10 CFR 2.705 - Discovery-additional methods.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Discovery-additional methods. 2.705 Section 2.705 Energy NUCLEAR REGULATORY COMMISSION AGENCY RULES OF PRACTICE AND PROCEDURE Rules for Formal Adjudications § 2... 147 and 181 of the Atomic Energy Act of 1954, as amended, the presiding officer may issue an...

  9. Evidence for Dose-Additive Effects of Pyrethroids on Motor Activity in Rats

    EPA Science Inventory

    BACKGROUND: Pyrethroids are neurotoxic insecticides used in a variety of indoor and outdoor applications. Previous research characterized the acute dose-effect functions for 11 pyrethroids administered orally in corn oil (1 mL/kg) based on assessment of motor activity. OBJECTIVES...

  10. Application of dose kernel calculation using a simplified Monte Carlo method to treatment plan for scanned proton beams.

    PubMed

    Mizutani, Shohei; Takada, Yoshihisa; Kohno, Ryosuke; Hotta, Kenji; Tansho, Ryohei; Akimoto, Tetsuo

    2016-03-01

    Full Monte Carlo (FMC) calculation of dose distribution has been recognized to have superior accuracy, compared with the pencil beam algorithm (PBA). However, since the FMC methods require long calculation time, it is difficult to apply them to routine treatment planning at present. In order to improve the situation, a simplified Monte Carlo (SMC) method has been introduced to the dose kernel calculation applicable to dose optimization procedure for the proton pencil beam scanning. We have evaluated accuracy of the SMC calculation by comparing a result of the dose kernel calculation using the SMC method with that using the FMC method in an inhomogeneous phantom. The dose distribution obtained by the SMC method was in good agreement with that obtained by the FMC method. To assess the usefulness of SMC calculation in clinical situations, we have compared results of the dose calculation using the SMC with those using the PBA method for three clinical cases of tumor treatment. The dose distributions calculated with the PBA dose kernels appear to be homogeneous in the planning target volumes (PTVs). In practice, the dose distributions calculated with the SMC dose kernels with the spot weights optimized with the PBA method show largely inhomogeneous dose distributions in the PTVs, while those with the spot weights optimized with the SMC method have moderately homogeneous distributions in the PTVs. Calculation using the SMC method is faster than that using the GEANT4 by three orders of magnitude. In addition, the graphic processing unit (GPU) boosts the calculation speed by 13 times for the treatment planning using the SMC method. Thence, the SMC method will be applicable to routine clinical treatment planning for reproduction of the complex dose distribution more accurately than the PBA method in a reasonably short time by use of the GPU-based calculation engine. PACS number(s): 87.55.Gh.

  11. Application of dose kernel calculation using a simplified Monte Carlo method to treatment plan for scanned proton beams.

    PubMed

    Mizutani, Shohei; Takada, Yoshihisa; Kohno, Ryosuke; Hotta, Kenji; Tansho, Ryohei; Akimoto, Tetsuo

    2016-03-08

    Full Monte Carlo (FMC) calculation of dose distribution has been recognized to have superior accuracy, compared with the pencil beam algorithm (PBA). However, since the FMC methods require long calculation time, it is difficult to apply them to routine treatment planning at present. In order to improve the situation, a simplified Monte Carlo (SMC) method has been introduced to the dose kernel calculation applicable to dose optimization procedure for the proton pencil beam scanning. We have evaluated accuracy of the SMC calculation by comparing a result of the dose kernel calculation using the SMC method with that using the FMC method in an inhomogeneous phantom. The dose distribution obtained by the SMC method was in good agreement with that obtained by the FMC method. To assess the usefulness of SMC calculation in clinical situations, we have compared results of the dose calculation using the SMC with those using the PBA method for three clinical cases of tumor treatment. The dose distributions calculated with the PBA dose kernels appear to be homogeneous in the planning target volumes (PTVs). In practice, the dose distributions calculated with the SMC dose kernels with the spot weights optimized with the PBA method show largely inhomogeneous dose distributions in the PTVs, while those with the spot weights optimized with the SMC method have moderately homogeneous distributions in the PTVs. Calculation using the SMC method is faster than that using the GEANT4 by three orders of magnitude. In addition, the graphic processing unit (GPU) boosts the calculation speed by 13 times for the treatment planning using the SMC method. Thence, the SMC method will be applicable to routine clinical treatment planning for reproduction of the complex dose distribution more accurately than the PBA method in a reasonably short time by use of the GPU-based calculation engine.

  12. Breakage and re-growth of flocs: effect of additional doses of coagulant species.

    PubMed

    Yu, Wenzheng; Gregory, John; Campos, Luiza C

    2011-12-15

    Several polyaluminum chloride (PACl) coagulants were prepared, with different OH/Al ratios (B values), and characterized by Ferron assay. These were used in studies of floc formation, breakage and re-growth with kaolin suspensions under controlled shear conditions, using a continuous optical monitoring method. Particular attention was paid to the effect of small additional coagulant dosages, added during the floc breakage period, on the re-growth of broken flocs. The results showed that the re-growth ability was greatly dependent on the nature of the PACl species added as second coagulant. The re-growth ability of broken flocs was greatest when the second coagulant was PACl(0) (i.e. AlCl(3), with B = 0) and least with PACl(25) (B = 2.5). In the latter case there was no effect on floc re-growth, irrespective of the initial coagulant used. PACls with intermediate B values gave some improvement in floc re-growth, but less than that with PACl(0). Additional dosage of PACl(0) gave re-grown flocs about the same size or even larger than those before breakage. The re-growth of broken flocs is significantly correlated with the species Al(a) (monomeric) and Al(b) (polymeric), as determined by Ferron assay. The amorphous hydroxide precipitate formed from PACl(0), (mainly Al(a)) can greatly improve the adhesion between broken flocs and give complete re-growth. However, for PACl(25), mostly composed of Al(b), the nature of the precipitate is different and there is no effect on floc re-growth.

  13. High-dose inhaled corticosteroids or addition of theophylline in patients with poorly controlled asthma?

    PubMed

    Celis, Pilar; Rada, Gabriel

    2015-08-19

    There are several management strategies for patients with poorly controlled asthma despite usual treatment. Increasing doses of inhaled corticosteroids or adding theophylline are among the therapeutic alternatives. However, the latter is associated with important adverse effects. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified only one systematic review including four pertinent randomized controlled trials. We combined the evidence using meta-analysis and generated a summary of findings following the GRADE approach. We concluded it is not clear whether theophylline or high-dose inhaled corticosteroids constitute a better alternative for symptomatic control or reduction in exacerbations in poorly controlled asthmatic patients because the certainty of the evidence is very low.

  14. High Dose β-Blocker Therapy Triggers Additional Reverse Remodeling in Patients With Idiopathic Non-Ischemic Cardiomyopathy.

    PubMed

    Nitta, Daisuke; Kinugawa, Koichiro; Imamura, Teruhiko; Kato, Naoko P; Komuro, Issei

    2016-12-02

    Carvedilol has established its evidence to improve prognosis and facilitate left ventricular reverse remodeling (LVRR) in heart failure patients with reduced left ventricular ejection fraction (LVEF), and many studies have supported its dose-dependency. However, there are few studies demonstrating the effect of high dose carvedilol in Japan. We enrolled 23 patients with idiopathic non-ischemic cardiomyopathy, in whom LVEF remained 45% or less despite 20 mg/ day of carvedilol therapy for > 3 months. After high dose (40 mg/day) carvedilol therapy for > 3 months, LVEF improved (+9.1%, P = 0.002), and LV end-diastolic diameter (LVDd) and LV end-systolic diameter (LVDs) reduced (-4.6 and -6.9 mm, respectively, P < 0.05) compared with the baseline data. Finally, 17 patients achieved LVRR after the high dose, when LVRR was defined as 1) those with final EF > 45%, and 2) those with final EF < 45% but who attained increases in LVEF > 10%, or LVEF > 5% with a decrease in LV end-diastolic dimension index (LVDDI) > 5%. Baseline predictors for LVRR after high dose carvedilol were the change rates of log B-type natriuretic peptide (BNP), LVDd, and LVDs from the time of pre-carvedilol introduction to enrollment (P < 0.05, respectively). In conclusion, high dose carvedilol triggered additional LVRR in patients with idiopathic non-ischemic cardiomyopathy and the change rates of log BNP, LVDd, and LVDs at 20 mg carvedilol may be predictors for the additional LVRR at high dose.

  15. An adaptive dose-finding method using a change-point model for molecularly targeted agents in phase I trials.

    PubMed

    Sato, Hiroyuki; Hirakawa, Akihiro; Hamada, Chikuma

    2016-10-15

    The paradigm of oncology drug development is expanding from developing cytotoxic agents to developing biological or molecularly targeted agents (MTAs). Although it is common for the efficacy and toxicity of cytotoxic agents to increase monotonically with dose escalation, the efficacy of some MTAs may exhibit non-monotonic patterns in their dose-efficacy relationships. Many adaptive dose-finding approaches in the available literature account for the non-monotonic dose-efficacy behavior by including additional model parameters. In this study, we propose a novel adaptive dose-finding approach based on binary efficacy and toxicity outcomes in phase I trials for monotherapy using an MTA. We develop a dose-efficacy model, the parameters of which are allowed to change in the vicinity of the change point of the dose level, in order to consider the non-monotonic pattern of the dose-efficacy relationship. The change point is obtained as the dose that maximizes the log-likelihood of the assumed dose-efficacy and dose-toxicity models. The dose-finding algorithm is based on the weighted Mahalanobis distance, calculated using the posterior probabilities of efficacy and toxicity outcomes. We compare the operating characteristics between the proposed and existing methods and examine the sensitivity of the proposed method by simulation studies under various scenarios. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Very low dose naltrexone addition in opioid detoxification: a randomized, controlled trial.

    PubMed

    Mannelli, Paolo; Patkar, Ashwin A; Peindl, Kathi; Gorelick, David A; Wu, Li-Tzy; Gottheil, Edward

    2009-04-01

    Although current treatments for opioid detoxification are not always effective, medical detoxification remains a required step before long-term interventions. The use of opioid antagonist medications to improve detoxification has produced inconsistent results. Very low dose naltrexone (VLNTX) was recently found to reduce opioid tolerance and dependence in animal and clinical studies. We decided to evaluate safety and efficacy of VLNTX adjunct to methadone in reducing withdrawal during detoxification. In a multi-center, double-blind, randomized study at community treatment programs, where most detoxifications are performed, 174 opioid-dependent subjects received NTX 0.125 mg, 0.250 mg or placebo daily for 6 days, together with methadone in tapering doses. VLNTX-treated individuals reported attenuated withdrawal symptoms [F = 7.24 (2,170); P = 0.001] and reduced craving [F = 3.73 (2,107); P = 0.03]. Treatment effects were more pronounced at discharge and were not accompanied by a significantly higher retention rate. There were no group differences in use of adjuvant medications and no treatment-related adverse events. Further studies should explore the use of VLNTX, combined with full and partial opioid agonist medications, in detoxification and long-term treatment of opioid dependence.

  17. Development of CT scanner models for patient organ dose calculations using Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Gu, Jianwei

    There is a serious and growing concern about the CT dose delivered by diagnostic CT examinations or image-guided radiation therapy imaging procedures. To better understand and to accurately quantify radiation dose due to CT imaging, Monte Carlo based CT scanner models are needed. This dissertation describes the development, validation, and application of detailed CT scanner models including a GE LightSpeed 16 MDCT scanner and two image guided radiation therapy (IGRT) cone beam CT (CBCT) scanners, kV CBCT and MV CBCT. The modeling process considered the energy spectrum, beam geometry and movement, and bowtie filter (BTF). The methodology of validating the scanner models using reported CTDI values was also developed and implemented. Finally, the organ doses to different patients undergoing CT scan were obtained by integrating the CT scanner models with anatomically-realistic patient phantoms. The tube current modulation (TCM) technique was also investigated for dose reduction. It was found that for RPI-AM, thyroid, kidneys and thymus received largest dose of 13.05, 11.41 and 11.56 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. For RPI-AF, thymus, small intestine and kidneys received largest dose of 10.28, 12.08 and 11.35 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. The dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. For MDCT with TCM schemas, the fetal dose can be reduced with 14%-25%. To demonstrate the applicability of the method proposed in this dissertation for modeling the CT scanner, additional MDCT scanner was modeled and validated by using the measured CTDI values. These results demonstrated that the

  18. Repeated dose titration versus age-based method in electroconvulsive therapy: a pilot study.

    PubMed

    Aten, Jan Jaap; Oudega, Mardien; van Exel, Eric; Stek, Max L; van Waarde, Jeroen A

    2015-06-01

    In electroconvulsive therapy (ECT), a dose titration method (DTM) was suggested to be more individualized and therefore more accurate than formula-based dosing methods. A repeated DTM (every sixth session and dose adjustment accordingly) was compared to an age-based method (ABM) regarding treatment characteristics, clinical outcome, and cognitive functioning after ECT. Thirty-nine unipolar depressed patients dosed using repeated DTM and 40 matched patients treated with ABM were compared. Montgomery-Åsberg Depression Rating Scale (MADRS) and Mini-Mental State Examination (MMSE) were assessed at baseline and at the end of the index course, as well as the total number of ECT sessions. Both groups were similar regarding age, sex, psychotic features, mean baseline MADRS, and median baseline MMSE. At the end of the index course, the two methods showed equal outcome (mean end MADRS, 11.6 ± 8.3 in DTM and 9.5 ± 7.6 in ABM (P = 0.26); median end MMSE, 28 (25-29) and 28 (25-29.8), respectively (P = 0.81). However, the median number of all ECT sessions differed 16 (11-22) in DTM versus 12 (10-14.8) in ABM; P = 0.02]. Using regression analysis, dosing method and age were independently associated with the total number of ECT sessions, with less sessions needed in ABM (P = 0.02) and in older patients (P = 0.001). In this comparative cohort study, ABM and DTM showed equal outcome for depression and cognition. However, the median ECT course duration in repeated DTM appeared longer. Additionally, higher age was associated with shorter ECT courses regardless of the dosing method. Further prospective studies are needed to confirm these findings.

  19. SU-E-J-06: Additional Imaging Guidance Dose to Patient Organs Resulting From X-Ray Tubes Used in CyberKnife Image Guidance System

    SciTech Connect

    Sullivan, A; Ding, G

    2015-06-15

    Purpose: The use of image-guided radiation therapy (IGRT) has become increasingly common, but the additional radiation exposure resulting from repeated image guidance procedures raises concerns. Although there are many studies reporting imaging dose from different image guidance devices, imaging dose for the CyberKnife Robotic Radiosurgery System is not available. This study provides estimated organ doses resulting from image guidance procedures on the CyberKnife system. Methods: Commercially available Monte Carlo software, PCXMC, was used to calculate average organ doses resulting from x-ray tubes used in the CyberKnife system. There are seven imaging protocols with kVp ranging from 60 – 120 kV and 15 mAs for treatment sites in the Cranium, Head and Neck, Thorax, and Abdomen. The output of each image protocol was measured at treatment isocenter. For each site and protocol, Adult body sizes ranging from anorexic to extremely obese were simulated since organ dose depends on patient size. Doses for all organs within the imaging field-of-view of each site were calculated for a single image acquisition from both of the orthogonal x-ray tubes. Results: Average organ doses were <1.0 mGy for every treatment site and imaging protocol. For a given organ, dose increases as kV increases or body size decreases. Higher doses are typically reported for skeletal components, such as the skull, ribs, or clavicles, than for softtissue organs. Typical organ doses due to a single exposure are estimated as 0.23 mGy to the brain, 0.29 mGy to the heart, 0.08 mGy to the kidneys, etc., depending on the imaging protocol and site. Conclusion: The organ doses vary with treatment site, imaging protocol and patient size. Although the organ dose from a single image acquisition resulting from two orthogonal beams is generally insignificant, the sum of repeated image acquisitions (>100) could reach 10–20 cGy for a typical treatment fraction.

  20. Methods for the additive manufacturing of semiconductor and crystal materials

    SciTech Connect

    Stowe, Ashley C.; Speight, Douglas

    2016-11-22

    A method for the additive manufacturing of inorganic crystalline materials, including: physically combining a plurality of starting materials that are used to form an inorganic crystalline compound to be used as one or more of a semiconductor, scintillator, laser crystal, and optical filter; heating or melting successive regions of the combined starting materials using a directed heat source having a predetermined energy characteristic, thereby facilitating the reaction of the combined starting materials; and allowing each region of the combined starting materials to cool in a controlled manner, such that the desired inorganic crystalline compound results. The method also includes, prior to heating or melting the successive regions of the combined starting materials using the directed heat source, heating the combined starting materials to facilitate initial reaction of the combined starting materials. The method further includes translating the combined starting materials and/or the directed heat source between successive locations. The method still further includes controlling the mechanical, electrical, photonic, and/or optical properties of the inorganic crystalline compound.

  1. Proton dose distribution measurements using a MOSFET detector with a simple dose-weighted correction method for LET effects.

    PubMed

    Kohno, Ryosuke; Hotta, Kenji; Matsuura, Taeko; Matsubara, Kana; Nishioka, Shie; Nishio, Teiji; Kawashima, Mitsuhiko; Ogino, Takashi

    2011-04-04

    We experimentally evaluated the proton beam dose reproducibility, sensitivity, angular dependence and depth-dose relationships for a new Metal Oxide Semiconductor Field Effect Transistor (MOSFET) detector. The detector was fabricated with a thinner oxide layer and was operated at high-bias voltages. In order to accurately measure dose distributions, we developed a practical method for correcting the MOSFET response to proton beams. The detector was tested by examining lateral dose profiles formed by protons passing through an L-shaped bolus. The dose reproducibility, angular dependence and depth-dose response were evaluated using a 190 MeV proton beam. Depth-output curves produced using the MOSFET detectors were compared with results obtained using an ionization chamber (IC). Since accurate measurements of proton dose distribution require correction for LET effects, we developed a simple dose-weighted correction method. The correction factors were determined as a function of proton penetration depth, or residual range. The residual proton range at each measurement point was calculated using the pencil beam algorithm. Lateral measurements in a phantom were obtained for pristine and SOBP beams. The reproducibility of the MOSFET detector was within 2%, and the angular dependence was less than 9%. The detector exhibited a good response at the Bragg peak (0.74 relative to the IC detector). For dose distributions resulting from protons passing through an L-shaped bolus, the corrected MOSFET dose agreed well with the IC results. Absolute proton dosimetry can be performed using MOSFET detectors to a precision of about 3% (1 sigma). A thinner oxide layer thickness improved the LET in proton dosimetry. By employing correction methods for LET dependence, it is possible to measure absolute proton dose using MOSFET detectors.

  2. Effect of inorganic salts and glucose additives on dose-response, melting point and mass density of genipin gel dosimeters.

    PubMed

    Al-jarrah, A M; Abdul Rahman, Azhar; Shahrim, Iskandar; Razak, Nik Noor Ashikin Nik Ab; Ababneh, Baker; Tousi, Ehsan Taghizadeh

    2016-01-01

    Genipin gel dosimeters are hydrogels infused with a radiation-sensitive material which yield dosimetric information in three dimensions (3D). The effect of inorganic salts and glucose on the visible absorption dose-response, melting points and mass density of genipin gel dosimeters has been experimentally evaluated using 6-MV LINAC photons. As a result, the addition of glucose with optimum concentration of 10% (w/w) was found to improve the thermal stability of the genipin gel and increase its melting point (Tm) by 6 °C accompanied by a slight decrease of dose-response. Furthermore, glucose helps to adjust the gel mass density to obtain the desired tissue-equivalent properties. A drop of Tm was observed when salts were used as additives. As the salt concentration increased, gel Tm decreased. The mass density and melting point of the genipin gel could be adjusted using different amounts of glucose that improved the genipin gel suitability for 3D dose measurements without introducing additional toxicity to the final gel.

  3. Solid form additives and method of forming same

    SciTech Connect

    Schuettenberg, A.D.; Gragson, J.T.

    1987-01-27

    This patent describes a solid form additive comprising: a normally liquid fuel additive selected from carburetor detergent additives, antiknock additives, deposit-control additives, and mixtures thereof, suitable for use in fuel comprising gasoline for internal combustion engines; and a structural agent for containing the fuel additive and for providing dimensional stability to the solid form additive, the structural agent being soluble and dispersible in the fuel; wherein the fuel additive comprises between about 25% and about 75% by weight of the solid form additive; and wherein the solid form additive is a pellet having structural agent and fuel additive essentially homogeneously dispersed throughout the solid form additive; and wherein the pellet is coated with a sealing agent.

  4. Low dose dynamic CT myocardial perfusion imaging using a statistical iterative reconstruction method

    SciTech Connect

    Tao, Yinghua; Chen, Guang-Hong; Hacker, Timothy A.; Raval, Amish N.; Van Lysel, Michael S.; Speidel, Michael A.

    2014-07-15

    Purpose: Dynamic CT myocardial perfusion imaging has the potential to provide both functional and anatomical information regarding coronary artery stenosis. However, radiation dose can be potentially high due to repeated scanning of the same region. The purpose of this study is to investigate the use of statistical iterative reconstruction to improve parametric maps of myocardial perfusion derived from a low tube current dynamic CT acquisition. Methods: Four pigs underwent high (500 mA) and low (25 mA) dose dynamic CT myocardial perfusion scans with and without coronary occlusion. To delineate the affected myocardial territory, an N-13 ammonia PET perfusion scan was performed for each animal in each occlusion state. Filtered backprojection (FBP) reconstruction was first applied to all CT data sets. Then, a statistical iterative reconstruction (SIR) method was applied to data sets acquired at low dose. Image voxel noise was matched between the low dose SIR and high dose FBP reconstructions. CT perfusion maps were compared among the low dose FBP, low dose SIR and high dose FBP reconstructions. Numerical simulations of a dynamic CT scan at high and low dose (20:1 ratio) were performed to quantitatively evaluate SIR and FBP performance in terms of flow map accuracy, precision, dose efficiency, and spatial resolution. Results: Forin vivo studies, the 500 mA FBP maps gave −88.4%, −96.0%, −76.7%, and −65.8% flow change in the occluded anterior region compared to the open-coronary scans (four animals). The percent changes in the 25 mA SIR maps were in good agreement, measuring −94.7%, −81.6%, −84.0%, and −72.2%. The 25 mA FBP maps gave unreliable flow measurements due to streaks caused by photon starvation (percent changes of +137.4%, +71.0%, −11.8%, and −3.5%). Agreement between 25 mA SIR and 500 mA FBP global flow was −9.7%, 8.8%, −3.1%, and 26.4%. The average variability of flow measurements in a nonoccluded region was 16.3%, 24.1%, and 937

  5. Low dose dynamic CT myocardial perfusion imaging using a statistical iterative reconstruction method

    PubMed Central

    Tao, Yinghua; Chen, Guang-Hong; Hacker, Timothy A.; Raval, Amish N.; Van Lysel, Michael S.; Speidel, Michael A.

    2014-01-01

    Purpose: Dynamic CT myocardial perfusion imaging has the potential to provide both functional and anatomical information regarding coronary artery stenosis. However, radiation dose can be potentially high due to repeated scanning of the same region. The purpose of this study is to investigate the use of statistical iterative reconstruction to improve parametric maps of myocardial perfusion derived from a low tube current dynamic CT acquisition. Methods: Four pigs underwent high (500 mA) and low (25 mA) dose dynamic CT myocardial perfusion scans with and without coronary occlusion. To delineate the affected myocardial territory, an N-13 ammonia PET perfusion scan was performed for each animal in each occlusion state. Filtered backprojection (FBP) reconstruction was first applied to all CT data sets. Then, a statistical iterative reconstruction (SIR) method was applied to data sets acquired at low dose. Image voxel noise was matched between the low dose SIR and high dose FBP reconstructions. CT perfusion maps were compared among the low dose FBP, low dose SIR and high dose FBP reconstructions. Numerical simulations of a dynamic CT scan at high and low dose (20:1 ratio) were performed to quantitatively evaluate SIR and FBP performance in terms of flow map accuracy, precision, dose efficiency, and spatial resolution. Results: Forin vivo studies, the 500 mA FBP maps gave −88.4%, −96.0%, −76.7%, and −65.8% flow change in the occluded anterior region compared to the open-coronary scans (four animals). The percent changes in the 25 mA SIR maps were in good agreement, measuring −94.7%, −81.6%, −84.0%, and −72.2%. The 25 mA FBP maps gave unreliable flow measurements due to streaks caused by photon starvation (percent changes of +137.4%, +71.0%, −11.8%, and −3.5%). Agreement between 25 mA SIR and 500 mA FBP global flow was −9.7%, 8.8%, −3.1%, and 26.4%. The average variability of flow measurements in a nonoccluded region was 16.3%, 24.1%, and 937

  6. Impacts of nitrogen addition on plant biodiversity in mountain grasslands depend on dose, application duration and climate: a systematic review.

    PubMed

    Humbert, Jean-Yves; Dwyer, John M; Andrey, Aline; Arlettaz, Raphaël

    2016-01-01

    Although the influence of nitrogen (N) addition on grassland plant communities has been widely studied, it is still unclear whether observed patterns and underlying mechanisms are constant across biomes. In this systematic review, we use meta-analysis and metaregression to investigate the influence of N addition (here referring mostly to fertilization) upon the biodiversity of temperate mountain grasslands (including montane, subalpine and alpine zones). Forty-two studies met our criteria of inclusion, resulting in 134 measures of effect size. The main general responses of mountain grasslands to N addition were increases in phytomass and reductions in plant species richness, as observed in lowland grasslands. More specifically, the analysis reveals that negative effects on species richness were exacerbated by dose (ha(-1) year(-1) ) and duration of N application (years) in an additive manner. Thus, sustained application of low to moderate levels of N over time had effects similar to short-term application of high N doses. The climatic context also played an important role: the overall effects of N addition on plant species richness and diversity (Shannon index) were less pronounced in mountain grasslands experiencing cool rather than warm summers. Furthermore, the relative negative effect of N addition on species richness was more pronounced in managed communities and was strongly negatively related to N-induced increases in phytomass, that is the greater the phytomass response to N addition, the greater the decline in richness. Altogether, this review not only establishes that plant biodiversity of mountain grasslands is negatively affected by N addition, but also demonstrates that several local management and abiotic factors interact with N addition to drive plant community changes. This synthesis yields essential information for a more sustainable management of mountain grasslands, emphasizing the importance of preserving and restoring grasslands with both low

  7. Fuzzy Filtering Method for Color Videos Corrupted by Additive Noise

    PubMed Central

    Ponomaryov, Volodymyr I.; Montenegro-Monroy, Hector; Nino-de-Rivera, Luis

    2014-01-01

    A novel method for the denoising of color videos corrupted by additive noise is presented in this paper. The proposed technique consists of three principal filtering steps: spatial, spatiotemporal, and spatial postprocessing. In contrast to other state-of-the-art algorithms, during the first spatial step, the eight gradient values in different directions for pixels located in the vicinity of a central pixel as well as the R, G, and B channel correlation between the analogous pixels in different color bands are taken into account. These gradient values give the information about the level of contamination then the designed fuzzy rules are used to preserve the image features (textures, edges, sharpness, chromatic properties, etc.). In the second step, two neighboring video frames are processed together. Possible local motions between neighboring frames are estimated using block matching procedure in eight directions to perform interframe filtering. In the final step, the edges and smoothed regions in a current frame are distinguished for final postprocessing filtering. Numerous simulation results confirm that this novel 3D fuzzy method performs better than other state-of-the-art techniques in terms of objective criteria (PSNR, MAE, NCD, and SSIM) as well as subjective perception via the human vision system in the different color videos. PMID:24688428

  8. Predicting dose-time profiles of solar energetic particle events using Bayesian forecasting methods.

    PubMed

    Neal, J S; Townsend, L W

    2001-12-01

    Bayesian inference techniques, coupled with Markov chain Monte Carlo sampling methods, are used to predict dose-time profiles for energetic solar particle events. Inputs into the predictive methodology are dose and dose-rate measurements obtained early in the event. Surrogate dose values are grouped in hierarchical models to express relationships among similar solar particle events. Models assume nonlinear, sigmoidal growth for dose throughout an event. Markov chain Monte Carlo methods are used to sample from Bayesian posterior predictive distributions for dose and dose rate. Example predictions are provided for the November 8, 2000, and August 12, 1989, solar particle events.

  9. Methods for detecting additional genes underlying Alzheimer disease

    SciTech Connect

    Locke, P.A.; Haines, J.L.; Ter-Minassian, M.

    1994-09-01

    Alzheimer`s disease (AD) is a complex inherited disorder with proven genetic heterogeneity. To date, genes on chromosome 21 (APP) and 14 (not yet identified) are associated with early-onset familial AD, while the APOE gene on chromosome 19 is associated with both late onset familial and sporadic AD and early onset sporadic AD. Although these genes likely account for the majority of AD, many familial cases cannot be traced to any of these genes. From a set of 127 late-onset multiplex families screened for APOE, 43 (34%) families have at least one affected individual with no APOE-4 allele, suggesting an alternative genetic etiology. Simulation studies indicated that additional loci could be identified through a genomic screen with a 10 cM sieve on a subset of 21 well documented, non-APOE-4 families. Given the uncertainties in the mode of inheritance, reliance on a single analytical method could result in a missed linkage. Therefore, we have developed a strategy of using multiple overlapping yet complementary methods to detect linkage. These include sib-pair analysis and affected-pedigree-member analysis, neither of which makes assumptions about mode of inheritance, and lod score analysis (using two predefined genetic models). In order for a marker to qualify for follow-up, it must fit at least two of three criteria. These are nominal P values of 0.05 or less for the non-parametric methods, and/or a lod score greater than 1.0. Adjacent markers each fulfilling a single criterion also warrant follow-up. To date, we have screened 61 markers on chromosomes 1, 2, 3, 18, 19, 21, and 22. One marker, D2S163, generated a lod score of 1.06 ({theta} = 0.15) and an APMT statistic of 3.68 (P < 0.001). This region is currently being investigated in more detail. Updated results of this region plus additional screening data will be presented.

  10. Technical Review of SRS Dose Reconstrruction Methods Used By CDC

    SciTech Connect

    Simpkins, Ali, A

    2005-07-20

    At the request of the Centers for Disease Control and Prevention (CDC), a subcontractor Advanced Technologies and Laboratories International, Inc.(ATL) issued a draft report estimating offsite dose as a result of Savannah River Site operations for the period 1954-1992 in support of Phase III of the SRS Dose Reconstruction Project. The doses reported by ATL differed than those previously estimated by Savannah River Site SRS dose modelers for a variety of reasons, but primarily because (1) ATL used different source terms, (2) ATL considered trespasser/poacher scenarios and (3) ATL did not consistently use site-specific parameters or correct usage parameters. The receptors with the highest dose from atmospheric and liquid pathways were within about a factor of four greater than dose values previously reported by SRS. A complete set of technical comments have also been included.

  11. USING DOSE ADDITION TO ESTIMATE CUMULATIVE RISKS FROM EXPOSURES TO MULTIPLE CHEMICALS

    EPA Science Inventory

    The Food Quality Protection Act (FQPA) of 1996 requires the EPA to consider the cumulative risk from exposure to multiple chemicals that have a common mechanism of toxicity. Three methods, hazard index (HI), point-of-departure index (PODI), and toxicity equivalence factor (TEF), ...

  12. Method for controlling a laser additive process using intrinsic illumination

    NASA Astrophysics Data System (ADS)

    Tait, Robert; Cai, Guoshuang; Azer, Magdi; Chen, Xiaobin; Liu, Yong; Harding, Kevin

    2015-05-01

    One form of additive manufacturing is to use a laser to generate a melt pool from powdered metal that is sprayed from a nozzle. The laser net-shape machining system builds the part a layer at a time by following a predetermined path. However, because the path may need to take many turns, maintaining a constant melt pool may not be easy. A straight section may require one speed and power while a sharp bend would over melt the metal at the same settings. This paper describes a process monitoring method that uses the intrinsic IR radiation from the melt pool along with a process model configured to establish target values for the parameters associated with the manufacture or repair. This model is based upon known properties of the metal being used as well as the properties of the laser beam. An adaptive control technique is then employed to control process parameters of the machining system based upon the real-time weld pool measurement. Since the system uses the heat radiant from the melt pool, other previously deposited metal does not confuse the system as only the melted material is seen by the camera.

  13. Low-dose adolescent nicotine and methylphenidate have additive effects on adult behavior and neurochemistry.

    PubMed

    Wheeler, Tracey L; Smith, Laura N; Bachus, Susan E; McDonald, Craig G; Fryxell, Karl J; Smith, Robert F

    2013-02-01

    Adolescents with Attention Deficit Hyperactivity Disorder (ADHD) have higher rates of smoking than adolescents without ADHD. Since methylphenidate is the primary drug used to treat ADHD, it is likely that many adolescents are exposed to both methylphenidate and nicotine. Recent studies have established that adolescent nicotine induces long-term changes in several neurobehavioral variables. Limited data also suggest that adolescent methylphenidate may affect neural development. Nicotine tolerance is a well-established behavioral phenomenon in rodents, yet the underlying mechanism remains elusive. Recent theories suggest that changes in ventral striatal dopamine indices may relate to nicotine tolerance. As an initial determination of whether nicotine and methylphenidate have additive effects on neurobehavioral development, the present study investigated the combined effects of adolescent nicotine [2mg/kg/d] alone or in conjunction with methylphenidate [1.5mg/kg, 2× daily] following a one-month drug free period on adult behavioral tolerance to nicotine [0.5mg/kg s.c.] and its relation to dopamine receptor mRNA expression in the ventral striatum. Animals with chronic combined (nicotine+methylphenidate) adolescent exposure displayed stronger tolerance as adults to the nicotine-induced locomotor effects in comparison to animals with adolescent exposure to nicotine alone, methylphenidate alone, or controls. Combined chronic adolescent exposure significantly elevated adult D3nf mRNA expression levels in the nucleus accumbens, however a single nicotine injection in adults increased D3nf mRNA levels in naïve animals and decreased D3nf mRNA levels in those that had been previously exposed to combined stimulants during adolescence. Conversely, a single adult nicotine injection increased D1 mRNA levels in the adult nucleus accumbens, particularly in the shell, but only in rats previously exposed to nicotine or methylphenidate as adolescents. To our knowledge this is the first

  14. Dose response of whey protein isolate in addition to a typical mixed meal on blood amino acids and hormonal concentrations.

    PubMed

    Forbes, Scott C; McCargar, Linda; Jelen, Paul; Bell, Gordon J

    2014-04-01

    The purpose was to investigate the effects of a controlled typical 1-day diet supplemented with two different doses of whey protein isolate on blood amino acid profiles and hormonal concentrations following the final meal. Nine males (age: 29.6 ± 6.3 yrs) completed four conditions in random order: a control (C) condition of a typical mixed diet containing ~10% protein (0.8 g·kg1), 65% carbohydrate, and 25% fat; a placebo (P) condition calorically matched with carbohydrate to the whey protein conditions; a low-dose condition of 0.8 grams of whey protein isolate per kilogram body mass per day (g·kg1·d1; W1) in addition to the typical mixed diet; or a high-dose condition of 1.6 g·kg1·d1 (W2) of supplemental whey protein in addition to the typical mixed diet. Following the final meal, significant (p < .05) increases in total amino acids, essential amino acids (EAA), branch-chained amino acids (BCAA), and leucine were observed in plasma with whey protein supplementation while no changes were observed in the control and placebo conditions. There was no significant group difference for glucose, insulin, testosterone, cortisol, or growth hormone. In conclusion, supplementing a typical daily food intake consisting of 0.8 g of protein·kg1·d1 with a whey protein isolate (an additional 0.8 or 1.6 g·kg1·d1) significantly elevated total amino acids, EAA, BCAA, and leucine but had no effect on glucose, insulin, testosterone, cortisol, or growth hormone following the final meal. Future acute and chronic supplementation research examining the physiological and health outcomes associated with elevated amino acid profiles is warranted.

  15. Interactive Rapid Dose Assessment Model (IRDAM): reactor-accident assessment methods. Vol. 2

    SciTech Connect

    Poeton, R.W.; Moeller, M.P.; Laughlin, G.J.; Desrosiers, A.E.

    1983-05-01

    As part of the continuing emphasis on emergency preparedness, the US Nuclear Regulatory Commission (NRC) sponsored the development of a rapid dose assessment system by Pacific Northwest Laboratory (PNL). This system, the Interactive Rapid Dose Assessment Model (IRDAM) is a micro-computer based program for rapidly assessing the radiological impact of accidents at nuclear power plants. This document describes the technical bases for IRDAM including methods, models and assumptions used in calculations. IRDAM calculates whole body (5-cm depth) and infant thyroid doses at six fixed downwind distances between 500 and 20,000 meters. Radionuclides considered primarily consist of noble gases and radioiodines. In order to provide a rapid assessment capability consistent with the capacity of the Osborne-1 computer, certain simplifying approximations and assumptions are made. These are described, along with default values (assumptions used in the absence of specific input) in the text of this document. Two companion volumes to this one provide additional information on IRDAM. The user's Guide (NUREG/CR-3012, Volume 1) describes the setup and operation of equipment necessary to run IRDAM. Scenarios for Comparing Dose Assessment Models (NUREG/CR-3012, Volume 3) provides the results of calculations made by IRDAM and other models for specific accident scenarios.

  16. Additives and method for controlling clathrate hydrates in fluid systems

    DOEpatents

    Sloan, Jr., Earle Dendy; Christiansen, Richard Lee; Lederhos, Joseph P.; Long, Jin Ping; Panchalingam, Vaithilingam; Du, Yahe; Sum, Amadeu Kun Wan

    1997-01-01

    Discussed is a process for preventing clathrate hydrate masses from detrimentally impeding the possible flow of a fluid susceptible to clathrate hydrate formation. The process is particularly useful in the natural gas and petroleum production, transportation and processing industry where gas hydrate formation can cause serious problems. Additives preferably contain one or more five member, six member and/or seven member cyclic chemical groupings. Additives include polymers having lactam rings. Additives can also contain polyelectrolytes that are believed to improve conformance of polymer additives through steric hinderance and/or charge repulsion. Also, polymers having an amide on which a C.sub.1 -C.sub.4 group is attached to the nitrogen and/or the carbonyl carbon of the amide may be used alone, or in combination with ring-containing polymers for enhanced effectiveness. Polymers having at least some repeating units representative of polymerizing at least one of an oxazoline, an N-substituted acrylamide and an N-vinyl alkyl amide are preferred.

  17. Additives and method for controlling clathrate hydrates in fluid systems

    DOEpatents

    Sloan, E.D. Jr.; Christiansen, R.L.; Lederhos, J.P.; Long, J.P.; Panchalingam, V.; Du, Y.; Sum, A.K.W.

    1997-06-17

    Discussed is a process for preventing clathrate hydrate masses from detrimentally impeding the possible flow of a fluid susceptible to clathrate hydrate formation. The process is particularly useful in the natural gas and petroleum production, transportation and processing industry where gas hydrate formation can cause serious problems. Additives preferably contain one or more five member, six member and/or seven member cyclic chemical groupings. Additives include polymers having lactam rings. Additives can also contain polyelectrolytes that are believed to improve conformance of polymer additives through steric hindrance and/or charge repulsion. Also, polymers having an amide on which a C{sub 1}-C{sub 4} group is attached to the nitrogen and/or the carbonyl carbon of the amide may be used alone, or in combination with ring-containing polymers for enhanced effectiveness. Polymers having at least some repeating units representative of polymerizing at least one of an oxazoline, an N-substituted acrylamide and an N-vinyl alkyl amide are preferred.

  18. Goodness-of-fit methods for additive-risk models in tumorigenicity experiments.

    PubMed

    Ghosh, Debashis

    2003-09-01

    In tumorigenicity experiments, a complication is that the time to event is generally not observed, so that the time to tumor is subject to interval censoring. One of the goals in these studies is to properly model the effect of dose on risk. Thus, it is important to have goodness of fit procedures available for assessing the model fit. While several estimation procedures have been developed for current-status data, relatively little work has been done on model-checking techniques. In this article, we propose numerical and graphical methods for the analysis of current-status data using the additive-risk model, primarily focusing on the situation where the monitoring times are dependent. The finite-sample properties of the proposed methodology are examined through numerical studies. The methods are then illustrated with data from a tumorigenicity experiment.

  19. A method for measuring the dose distribution of the radiotherapy domain using the computed radiography system.

    PubMed

    Homma, Mitsuhiko; Tabushi, Katsuyoshi; Obata, Yasunori; Tamiya, Tadashi; Koyama, Shuji; Ishigaki, Takeo

    2002-01-01

    Knowing the dose distribution in a tissue is as important as being able to measure exposure or absorbed dose in radiotherapy. Therefore, we have developed a measurement method for the dose distribution (CR dosimetry) in the phantom based on the imaging plate (IP) of the computed radiography (CR). The IP was applied for the dose measurement as a dosimeter instead of the film used for film dosimetry. The data from the irradiated IP were processed by a personal computer with 10 bits and were depicted as absorbed dose distributions in the phantom. The image of the dose distribution was obtained from the CR system using the DICOM form. The CR dosimetry is an application of CR system currently employed in medical examinations to dosimetry in radiotherapy. A dose distribution can be easily shown by the Dose Distribution Depiction System we developed this time. Moreover, the measurement method is simpler and a result is obtained more quickly compared with film dosimetry.

  20. Gasoline and Diesel Fuel Test Methods Additional Resources

    EPA Pesticide Factsheets

    Supporting documents on the Direct Final Rule that allows refiners and laboratories to use more current and improved fuel testing procedures for twelve American Society for Testing and Materials analytical test methods.

  1. SU-E-T-280: Reconstructed Rectal Wall Dose Map-Based Verification of Rectal Dose Sparing Effect According to Rectum Definition Methods and Dose Perturbation by Air Cavity in Endo-Rectal Balloon

    SciTech Connect

    Park, J; Park, H; Lee, J; Kang, S; Lee, M; Suh, T; Lee, B

    2014-06-01

    Purpose: Dosimetric effect and discrepancy according to the rectum definition methods and dose perturbation by air cavity in an endo-rectal balloon (ERB) were verified using rectal-wall (Rwall) dose maps considering systematic errors in dose optimization and calculation accuracy in intensity-modulated radiation treatment (IMRT) for prostate cancer patients. Methods: When the inflated ERB having average diameter of 4.5 cm and air volume of 100 cc is used for patient, Rwall doses were predicted by pencil-beam convolution (PBC), anisotropic analytic algorithm (AAA), and AcurosXB (AXB) with material assignment function. The errors of dose optimization and calculation by separating air cavity from the whole rectum (Rwhole) were verified with measured rectal doses. The Rwall doses affected by the dose perturbation of air cavity were evaluated using a featured rectal phantom allowing insert of rolled-up gafchromic films and glass rod detectors placed along the rectum perimeter. Inner and outer Rwall doses were verified with reconstructed predicted rectal wall dose maps. Dose errors and extent at dose levels were evaluated with estimated rectal toxicity. Results: While AXB showed insignificant difference of target dose coverage, Rwall doses underestimated by up to 20% in dose optimization for the Rwhole than Rwall at all dose range except for the maximum dose. As dose optimization for Rwall was applied, the Rwall doses presented dose error less than 3% between dose calculation algorithm except for overestimation of maximum rectal dose up to 5% in PBC. Dose optimization for Rwhole caused dose difference of Rwall especially at intermediate doses. Conclusion: Dose optimization for Rwall could be suggested for more accurate prediction of rectal wall dose prediction and dose perturbation effect by air cavity in IMRT for prostate cancer. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea

  2. System and method for high power diode based additive manufacturing

    DOEpatents

    El-Dasher, Bassem S.; Bayramian, Andrew; Demuth, James A.; Farmer, Joseph C.; Torres, Sharon G.

    2016-04-12

    A system is disclosed for performing an Additive Manufacturing (AM) fabrication process on a powdered material forming a substrate. The system may make use of a diode array for generating an optical signal sufficient to melt a powdered material of the substrate. A mask may be used for preventing a first predetermined portion of the optical signal from reaching the substrate, while allowing a second predetermined portion to reach the substrate. At least one processor may be used for controlling an output of the diode array.

  3. Addition and Subtraction. Mathematics-Methods Program Unit.

    ERIC Educational Resources Information Center

    LeBlanc, John F.; And Others

    This unit is 1 of 12 developed for the university classroom portion of the Mathematics-Methods Program (MMP), created by the Indiana University Mathematics Education Development Center (MEDC) as an innovative program for the mathematics training of prospective elementary school teachers (PSTs). Each unit is written in an activity format that…

  4. A new method for calculating the accumulated dose in ESR dating and retrospective dosimetry.

    PubMed

    Oliveira, Luiz Carlos; Kinoshita, Angela; Lopes, Renato P; Baffa, Oswaldo

    2010-02-01

    Dose evaluation by electron spin resonance (ESR) is usually accomplished by constructing a dose-response curve by measuring the peak-to-peak intensity of the dosimetric signals in the g = 2 region. In several cases, this signal is overlapped with others that can interfere with dose reconstruction. In this work a new method to correct the spectrum before the measurement of the signal intensity is proposed. Examples of dose determination of accumulated dose (AD) of two fossil teeth from southern Brazilian megafauna are given. One of them presents a dose-independent signal in the region of interest, and the validity of this method is shown. For the other, without interfering signals, no difference in the AD was found. This method can also be applied to retrospective dosimetry by ESR for any sample with dose-independent interfering signals, thus improving the accuracy in AD determination by ESR.

  5. Recommended environmental dose calculation methods and Hanford-specific parameters

    SciTech Connect

    Schreckhise, R.G.; Rhoads, K.; Napier, B.A.; Ramsdell, J.V. ); Davis, J.S. )

    1993-03-01

    This document was developed to support the Hanford Environmental Dose overview Panel (HEDOP). The Panel is responsible for reviewing all assessments of potential doses received by humans and other biota resulting from the actual or possible environmental releases of radioactive and other hazardous materials from facilities and/or operations belonging to the US Department of Energy on the Hanford Site in south-central Washington. This document serves as a guide to be used for developing estimates of potential radiation doses, or other measures of risk or health impacts, to people and other biota in the environs on and around the Hanford Site. It provides information to develop technically sound estimates of exposure (i.e., potential or actual) to humans or other biotic receptors that could result from the environmental transport of potentially harmful materials that have been, or could be, released from Hanford operations or facilities. Parameter values and information that are specific to the Hanford environs as well as other supporting material are included in this document.

  6. SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

    SciTech Connect

    Supanich, MP

    2015-06-15

    Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in the central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG.

  7. Method for simultaneous use of a single additive for coal flotation, dewatering, and reconstitution

    DOEpatents

    Wen, Wu-Wey; Gray, McMahan L.; Champagne, Kenneth J.

    1995-01-01

    A single dose of additive contributes to three consecutive fine coal unit operations, i.e., flotation, dewatering and reconstitution, whereby the fine coal is first combined with water in a predetermined proportion so as to formulate a slurry. The slurry is then mixed with a heavy hydrocarbon-based emulsion in a second predetermined proportion and at a first predetermined mixing speed and for a predetermined period of time. The conditioned slurry is then cleaned by a froth flotation method to form a clean coal froth and then the froth is dewatered by vacuum filtration or a centrifugation process to form reconstituted products that are dried to dust-less clumps prior to combustion.

  8. Method for simultaneous use of a single additive for coal flotation, dewatering and reconstitution

    SciTech Connect

    Wen, Wu-Wey; Gray, M.L.; Champagne, K.J.

    1993-11-09

    A single dose of additive contributes to three consecutive fine coal unit operations, i.e., flotation, dewatering and reconstitution, whereby the fine coal is first combined with water in a predetermined proportion so as to formulate a slurry. The slurry is then mixed with a heavy hydrocarbon-based emulsion in a second predetermined proportion and at a first predetermined mixing speed and for a predetermined period of time. The conditioned slurry is then cleaned by a froth flotation method to form a clean coal froth and then the froth is dewatered by vacuum filtration or a centrifugation process to form reconstituted products that are dried to dust-less clumps prior to combustion.

  9. SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

    SciTech Connect

    Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L

    2015-06-15

    Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to the thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low.

  10. Appropriate statistical methods to compare dose responses of methionine sources.

    PubMed

    Kratzer, D D; Littell, R C

    2006-05-01

    Two sources of methionine (Met) activity are frequently used in commercial feed formulation: DL-2-hydroxy-4-(methylthio) butanoic acid (HMTBA), most commonly available as an 88% solution with 12% water; and DL-methionine (DLM, 99% powder). Despite the fact that both compounds have been in commercial use for over 50 yr, controversy and confusion remain with respect to their relative bioefficacy (RBE). This paper presents a review of the use of a nonlinear common plateau asymptotic regression technique (NLCPAR) that has been used to compare the 2 Met sources with particular emphasis on the validity of the basic assumptions of that model. The thesis of this paper is that the controversy is due, at least in part, to the misapplication of this regression technique to estimate the RBE of HMTBA and DLM. The NLCPAR model is a bioassay with the key dependent assumptions that HMTBA is a dilution of DLM, and that each follows dose-response curves of the same form and approach a common plateau. Because both provide Met activity, it may be considered reasonable to accept these assumptions; however, specifically testing them demonstrated that the assumption of a common dose-response is not supported by data. The common plateau assumption was tested with an alternative approach of fitting nonlinear separate plateaus asymptotic regression (NLSPAR) to a set of 13 published broiler studies in which the NLCPAR model had been used to estimate RBE of HMTBA and DLM. The hypothesis of a common plateau was rejected (P < 0.01), meaning that the conclusion that HMTBA had lower bioefficacy than DLM based on the NLCPAR methodology was not valid. An example using published data demonstrated that the NLSPAR model was a significantly better fit than the NLCPAR model, and showed that HMTBA and DLM followed different dose responses. Consequently, there was no single value for RBE for the entire dose range; rather, the RBE of the 2 compounds varied with use level. The evidence presented here

  11. Early treatment with addition of low dose prednisolone to methotrexate improves therapeutic outcome in severe psoriatic arthritis.

    PubMed

    Mahajan, Vikram K; Sharma, Anju Lath; Chauhan, Pushpinder S; Mehta, Karaninder S; Sharma, Nand Lal

    2013-05-01

    Psoriatic arthritis (PsA) is increasingly being recognized to cause progressive joint damage and disability. PsA unresponsive to non-steroidal anti-inflammatory drugs (NSAIDs), the conventional first-line choice of treatment, is usually managed with disease-modifying antirheumatic drugs (DMARDs) especially methotrexate. An 18-year-old HIV-negative male had progressively severe PsA of 4-month duration that was nearly confining him to a wheel chair. He did not respond to multiple NSAIDs, alone or in combination with methotrexate (15 mg/week), given for 4 weeks. Addition of prednisolone (10 mg on alternate days) controlled his symptoms within a week. The NSAIDs could be withdrawn after 4 weeks as the treatment progressed. The doses were tapered for methotrexate (5 mg/week) and prednisolone (2.5 mg on alternate days) every 8 weekly subsequently during 15 months of follow-up without recurrence/deformities or drug toxicity. For years, the use of corticosteroids in psoriasis has been criticized for their propensity to exacerbate the skin disease on withdrawal. However, monitored use of corticosteroids, even in low doses, combined with DMARDs may be a good therapeutic option in early stage of the PsA rather than 'steroid rescue' later. This will help in early control of joint inflammation, prevent joint damage and maintain long-term good functional capacity and quality of life. This may be useful when the cost or availability of biologics precludes their use. However, we discourage the use of corticosteroids as monotherapy.

  12. Monitoring Method of Cutting Force by Using Additional Spindle Sensors

    NASA Astrophysics Data System (ADS)

    Sarhan, Ahmed Aly Diaa; Matsubara, Atsushi; Sugihara, Motoyuki; Saraie, Hidenori; Ibaraki, Soichi; Kakino, Yoshiaki

    This paper describes a monitoring method of cutting forces for end milling process by using displacement sensors. Four eddy-current displacement sensors are installed on the spindle housing of a machining center so that they can detect the radial motion of the rotating spindle. Thermocouples are also attached to the spindle structure in order to examine the thermal effect in the displacement sensing. The change in the spindle stiffness due to the spindle temperature and the speed is investigated as well. Finally, the estimation performance of cutting forces using the spindle displacement sensors is experimentally investigated by machining tests on carbon steel in end milling operations under different cutting conditions. It is found that the monitoring errors are attributable to the thermal displacement of the spindle, the time lag of the sensing system, and the modeling error of the spindle stiffness. It is also shown that the root mean square errors between estimated and measured amplitudes of cutting forces are reduced to be less than 20N with proper selection of the linear stiffness.

  13. Methods of space radiation dose analysis with applications to manned space systems

    NASA Technical Reports Server (NTRS)

    Langley, R. W.; Billings, M. P.

    1972-01-01

    The full potential of state-of-the-art space radiation dose analysis for manned missions has not been exploited. Point doses have been overemphasized, and the critical dose to the bone marrow has been only crudely approximated, despite the existence of detailed man models and computer codes for dose integration in complex geometries. The method presented makes it practical to account for the geometrical detail of the astronaut as well as the vehicle. Discussed are the major assumptions involved and the concept of applying the results of detailed proton dose analysis to the real-time interpretation of on-board dosimetric measurements.

  14. Dose calculation and in-phantom measurement in BNCT using response matrix method.

    PubMed

    Rahmani, Faezeh; Shahriari, Majid

    2011-12-01

    In-phantom measurement of physical dose distribution is very important for Boron Neutron Capture Therapy (BNCT) planning validation. If any changes take place in therapeutic neutron beam due to the beam shaping assembly (BSA) change, the dose will be changed so another group of simulations should be carried out for dose calculation. To avoid this time consuming procedure and speed up the dose calculation to help patients not wait for a long time, response matrix method was used. This procedure was performed for neutron beam of the optimized BSA as a reference beam. These calculations were carried out using the MCNPX, Monte Carlo code. The calculated beam parameters were measured for a SNYDER head phantom placed 10 cm away from beam the exit of the BSA. The head phantom can be assumed as a linear system and neutron beam and dose distribution can be assumed as an input and a response of this system (head phantom), respectively. Neutron spectrum energy was digitized into 27 groups. Dose response of each group was calculated. Summation of these dose responses is equal to a total dose of the whole neutron/gamma spectrum. Response matrix is the double dimension matrix (energy/dose) in which each parameter represents a depth-dose resulted from specific energy. If the spectrum is changed, response of each energy group may be differed. By considering response matrix and energy vector, dose response can be calculated. This method was tested for some BSA, and calculations show statistical errors less than 10%.

  15. Dual-source dual-energy CT with additional tin filtration: Dose and image quality evaluation in phantoms and in-vivo

    PubMed Central

    Primak, Andrew N.; Giraldo, Juan Carlos Ramirez; Eusemann, Christian D.; Schmidt, Bernhard; Kantor, B.; Fletcher, Joel G.; McCollough, Cynthia H.

    2010-01-01

    Purpose To investigate the effect on radiation dose and image quality of the use of additional spectral filtration for dual-energy CT (DECT) imaging using dual-source CT (DSCT). Materials and Methods A commercial DSCT scanner was modified by adding tin filtration to the high-kV tube, and radiation output and noise measured in water phantoms. Dose values for equivalent image noise were compared among DE-modes with and without tin filtration and single-energy (SE) mode. To evaluate DECT material discrimination, the material-specific DEratio for calcium and iodine were determined using images of anthropomorphic phantoms. Data were additionally acquired in 38 and 87 kg pigs, and noise for the linearly mixed and virtual non-contrast (VNC) images compared between DE-modes. Finally, abdominal DECT images from two patients of similar sizes undergoing clinically-indicated CT were compared. Results Adding tin filtration to the high-kV tube improved the DE contrast between iodine and calcium as much as 290%. Pig data showed that the tin filtration had no effect on noise in the DECT mixed images, but decreased noise by as much as 30% in the VNC images. Patient VNC-images acquired using 100/140 kV with added tin filtration had improved image quality compared to those generated with 80/140 kV without tin filtration. Conclusion Tin filtration of the high-kV tube of a DSCT scanner increases the ability of DECT to discriminate between calcium and iodine, without increasing dose relative to SECT. Furthermore, use of 100/140 kV tube potentials allows improved DECT imaging of large patients. PMID:20966323

  16. Assessment of the Annual Additional Effective Doses amongst Minamisoma Children during the Second Year after the Fukushima Daiichi Nuclear Power Plant Disaster.

    PubMed

    Tsubokura, Masaharu; Kato, Shigeaki; Morita, Tomohiro; Nomura, Shuhei; Kami, Masahiro; Sakaihara, Kikugoro; Hanai, Tatsuo; Oikawa, Tomoyoshi; Kanazawa, Yukio

    2015-01-01

    An assessment of the external and internal radiation exposure levels, which includes calculation of effective doses from chronic radiation exposure and assessment of long-term radiation-related health risks, has become mandatory for residents living near the nuclear power plant in Fukushima, Japan. Data for all primary and secondary children in Minamisoma who participated in both external and internal screening programs were employed to assess the annual additional effective dose acquired due to the Fukushima Daiichi nuclear power plant disaster. In total, 881 children took part in both internal and external radiation exposure screening programs between 1st April 2012 to 31st March 2013. The level of additional effective doses ranged from 0.025 to 3.49 mSv/year with the median of 0.70 mSv/year. While 99.7% of the children (n = 878) were not detected with internal contamination, 90.3% of the additional effective doses was the result of external radiation exposure. This finding is relatively consistent with the doses estimated by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The present study showed that the level of annual additional effective doses among children in Minamisoma has been low, even after the inter-individual differences were taken into account. The dose from internal radiation exposure was negligible presumably due to the success of contaminated food control.

  17. Assessment of the Annual Additional Effective Doses amongst Minamisoma Children during the Second Year after the Fukushima Daiichi Nuclear Power Plant Disaster

    PubMed Central

    Tsubokura, Masaharu; Kato, Shigeaki; Morita, Tomohiro; Nomura, Shuhei; Kami, Masahiro; Sakaihara, Kikugoro; Hanai, Tatsuo; Oikawa, Tomoyoshi; Kanazawa, Yukio

    2015-01-01

    An assessment of the external and internal radiation exposure levels, which includes calculation of effective doses from chronic radiation exposure and assessment of long-term radiation-related health risks, has become mandatory for residents living near the nuclear power plant in Fukushima, Japan. Data for all primary and secondary children in Minamisoma who participated in both external and internal screening programs were employed to assess the annual additional effective dose acquired due to the Fukushima Daiichi nuclear power plant disaster. In total, 881 children took part in both internal and external radiation exposure screening programs between 1st April 2012 to 31st March 2013. The level of additional effective doses ranged from 0.025 to 3.49 mSv/year with the median of 0.70 mSv/year. While 99.7% of the children (n = 878) were not detected with internal contamination, 90.3% of the additional effective doses was the result of external radiation exposure. This finding is relatively consistent with the doses estimated by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The present study showed that the level of annual additional effective doses among children in Minamisoma has been low, even after the inter-individual differences were taken into account. The dose from internal radiation exposure was negligible presumably due to the success of contaminated food control. PMID:26053271

  18. A method of estimating conceptus doses resulting from multidetector CT examinations during all stages of gestation

    SciTech Connect

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

    2010-12-15

    Purpose: Current methods for the estimation of conceptus dose from multidetector CT (MDCT) examinations performed on the mother provide dose data for typical protocols with a fixed scan length. However, modified low-dose imaging protocols are frequently used during pregnancy. The purpose of the current study was to develop a method for the estimation of conceptus dose from any MDCT examination of the trunk performed during all stages of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study to model the Siemens Sensation 16 and Sensation 64 MDCT scanners. Four mathematical phantoms were used, simulating women at 0, 3, 6, and 9 months of gestation. The contribution to the conceptus dose from single simulated scans was obtained at various positions across the phantoms. To investigate the effect of maternal body size and conceptus depth on conceptus dose, phantoms of different sizes were produced by adding layers of adipose tissue around the trunk of the mathematical phantoms. To verify MCNP results, conceptus dose measurements were carried out by means of three physical anthropomorphic phantoms, simulating pregnancy at 0, 3, and 6 months of gestation and thermoluminescence dosimetry (TLD) crystals. Results: The results consist of Monte Carlo-generated normalized conceptus dose coefficients for single scans across the four mathematical phantoms. These coefficients were defined as the conceptus dose contribution from a single scan divided by the CTDI free-in-air measured with identical scanning parameters. Data have been produced to take into account the effect of maternal body size and conceptus position variations on conceptus dose. Conceptus doses measured with TLD crystals showed a difference of up to 19% compared to those estimated by mathematical simulations. Conclusions: Estimation of conceptus doses from MDCT examinations of the trunk performed on pregnant patients during all stages of gestation can be made

  19. A method for the evaluation of dose-effect data utilizing a programmable calculator.

    PubMed

    Carmines, E L; Carchman, R A; Borzelleca, J F

    1980-08-01

    A program for the calculation of the median effective dose (ED50) and the slope of the dose-effect line was developed for a programmable calculator. The method employed approximated the solution described by Bliss. Experimental data were evaluated and compared to both hand calculated results and results of other computer methods. This method produced results which differed from other computer methods by less than 1 percent. This program provided information necessary for the test for parallelism and estimate of relative potency of two dose-effect lines.

  20. A method for estimating occupational radiation dose to individuals, using weekly dosimetry data

    SciTech Connect

    Mitchell, T.J.; Ostrouchov, G.; Frome, E.L.; Kerr, G.D.

    1993-12-01

    Statistical analyses of data from epidemiologic studies of workers exposed to radiation have been based on recorded annual radiation doses. It is usually assumed that the annual dose values are known exactly, although it is generally recognized that the data contain uncertainty due to measurement error and bias. We propose the use of a probability distribution to describe an individual`s dose during a specific period of time. Statistical methods for estimating this dose distribution are developed. The methods take into account the ``measurement error`` that is produced by the dosimetry system, and the bias that was introduced by policies that lead to right censoring of small doses as zero. The method is applied to a sample of dose histories obtained from hard copy dosimetry records at Oak Ridge National Laboratory (ORNL). The result of this evaluation raises serious questions about the validity of the historical personnel dosimetry data that is currently being used in low-dose studies of nuclear industry workers. In particular, it appears that there was a systematic underestimation of doses for ORNL workers. This could result in biased estimates of dose-response coefficients and their standard errors.

  1. SEMICONDUCTOR TECHNOLOGY: An efficient dose-compensation method for proximity effect correction

    NASA Astrophysics Data System (ADS)

    Ying, Wang; Weihua, Han; Xiang, Yang; Renping, Zhang; Yang, Zhang; Fuhua, Yang

    2010-08-01

    A novel simple dose-compensation method is developed for proximity effect correction in electron-beam lithography. The sizes of exposed patterns depend on dose factors while other exposure parameters (including accelerate voltage, resist thickness, exposing step size, substrate material, and so on) remain constant. This method is based on two reasonable assumptions in the evaluation of the compensated dose factor: one is that the relation between dose factors and circle-diameters is linear in the range under consideration; the other is that the compensated dose factor is only affected by the nearest neighbors for simplicity. Four-layer-hexagon photonic crystal structures were fabricated as test patterns to demonstrate this method. Compared to the uncorrected structures, the homogeneity of the corrected hole-size in photonic crystal structures was clearly improved.

  2. A semiempirical method for the description of relative crossbeam dose profiles at depth from linear accelerators.

    PubMed

    Tsalafoutas, I; Xenofos, S; Stamatelatos, I E

    1997-01-01

    A semiempirical method for the calculation of the relative crossbeam dose profiles at depth is described. The parameters required to set up the formulae and their dependence with field size and depth are investigated. Using the above method, measured crossbeam dose profiles at depth from two linear accelerators, Philips (SL-18) and AEC (Therac-6) are reproduced. The results indicate that this method is applicable within a wide range of depths and field sizes.

  3. Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation.

    PubMed

    Anderson, Catherine; Malambo, Dennis Hanjalika; Perez, Maria Eliette Gonzalez; Nobela, Happiness Ngwanamoseka; de Pooter, Lobke; Spit, Jan; Hooijmans, Christine Maria; de Vossenberg, Jack van; Greya, Wilson; Thole, Bernard; van Lier, Jules B; Brdjanovic, Damir

    2015-10-29

    In this research, three faecal sludge sanitizing methods-lactic acid fermentation, urea treatment and lime treatment-were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m³ of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment.

  4. Apparatus and method for high dose rate brachytherapy radiation treatment

    DOEpatents

    Macey, Daniel J.; Majewski, Stanislaw; Weisenberger, Andrew G.; Smith, Mark Frederick; Kross, Brian James

    2005-01-25

    A method and apparatus for the in vivo location and tracking of a radioactive seed source during and after brachytherapy treatment. The method comprises obtaining multiple views of the seed source in a living organism using: 1) a single PSPMT detector that is exposed through a multiplicity of pinholes thereby obtaining a plurality of images from a single angle; 2) a single PSPMT detector that may obtain an image through a single pinhole or a plurality of pinholes from a plurality of angles through movement of the detector; or 3) a plurality of PSPMT detectors that obtain a plurality of views from different angles simultaneously or virtually simultaneously. The plurality of images obtained from these various techniques, through angular displacement of the various acquired images, provide the information required to generate the three dimensional images needed to define the location of the radioactive seed source within the body of the living organism.

  5. 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.

  6. Developing a multipoint titration method with a variable dose implementation for anaerobic digestion monitoring.

    PubMed

    Salonen, K; Leisola, M; Eerikäinen, T

    2009-01-01

    Determination of metabolites from an anaerobic digester with an acid base titration is considered as superior method for many reasons. This paper describes a practical at line compatible multipoint titration method. The titration procedure was improved by speed and data quality. A simple and novel control algorithm for estimating a variable titrant dose was derived for this purpose. This non-linear PI-controller like algorithm does not require any preliminary information from sample. Performance of this controller is superior compared to traditional linear PI-controllers. In addition, simplification for presenting polyprotic acids as a sum of multiple monoprotic acids is introduced along with a mathematical error examination. A method for inclusion of the ionic strength effect with stepwise iteration is shown. The titration model is presented with matrix notations enabling simple computation of all concentration estimates. All methods and algorithms are illustrated in the experimental part. A linear correlation better than 0.999 was obtained for both acetate and phosphate used as model compounds with slopes of 0.98 and 1.00 and average standard deviations of 0.6% and 0.8%, respectively. Furthermore, insensitivity of the presented method for overlapping buffer capacity curves was shown.

  7. Imaging method for monitoring delivery of high dose rate brachytherapy

    DOEpatents

    Weisenberger, Andrew G; Majewski, Stanislaw

    2012-10-23

    A method for in-situ monitoring both the balloon/cavity and the radioactive source in brachytherapy treatment utilizing using at least one pair of miniature gamma cameras to acquire separate images of: 1) the radioactive source as it is moved in the tumor volume during brachytherapy; and 2) a relatively low intensity radiation source produced by either an injected radiopharmaceutical rendering cancerous tissue visible or from a radioactive solution filling a balloon surgically implanted into the cavity formed by the surgical resection of a tumor.

  8. 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

  9. 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

  10. SU-E-T-465: Dose Calculation Method for Dynamic Tumor Tracking Using a Gimbal-Mounted Linac

    SciTech Connect

    Sugimoto, S; Inoue, T; Kurokawa, C; Usui, K; Sasai, K; Utsunomiya, S; Ebe, K

    2014-06-01

    Purpose: Dynamic tumor tracking using the gimbal-mounted linac (Vero4DRT, Mitsubishi Heavy Industries, Ltd., Japan) has been available when respiratory motion is significant. The irradiation accuracy of the dynamic tumor tracking has been reported to be excellent. In addition to the irradiation accuracy, a fast and accurate dose calculation algorithm is needed to validate the dose distribution in the presence of respiratory motion because the multiple phases of it have to be considered. A modification of dose calculation algorithm is necessary for the gimbal-mounted linac due to the degrees of freedom of gimbal swing. The dose calculation algorithm for the gimbal motion was implemented using the linear transformation between coordinate systems. Methods: The linear transformation matrices between the coordinate systems with and without gimbal swings were constructed using the combination of translation and rotation matrices. The coordinate system where the radiation source is at the origin and the beam axis along the z axis was adopted. The transformation can be divided into the translation from the radiation source to the gimbal rotation center, the two rotations around the center relating to the gimbal swings, and the translation from the gimbal center to the radiation source. After operating the transformation matrix to the phantom or patient image, the dose calculation can be performed as the no gimbal swing. The algorithm was implemented in the treatment planning system, PlanUNC (University of North Carolina, NC). The convolution/superposition algorithm was used. The dose calculations with and without gimbal swings were performed for the 3 × 3 cm{sup 2} field with the grid size of 5 mm. Results: The calculation time was about 3 minutes per beam. No significant additional time due to the gimbal swing was observed. Conclusions: The dose calculation algorithm for the finite gimbal swing was implemented. The calculation time was moderate.

  11. Fetal dose assessment from invasive special procedures by Monte Carlo methods.

    PubMed

    Metzger, R L; Van Riper, K A

    1999-08-01

    The assessment of fetal dose from a special procedure in the clinical environment is difficult as patient size, fluoroscopic beam motion, and imaging sequences vary significantly from study to study. Fetal dose is particularly difficult to estimate when the fetus is exposed partially or totally to scatter radiation from images taken in other locations of the mother's body. A method to reliably estimate fetal dose has been developed by using template based input files for the Monte Carlo radiation transport code MCNP. Female patient phantoms at 0, 3, 6, and 9 months of pregnancy and source terms for common diagnostic tube potentials are used to rapidly build an input file for MCNP. The phantoms can be easily modified to fit patient shape. The geometry and beam location for each type of image acquired (i.e. fluoroscopy, spot filming, etc.) is verified by the use of a 3D visualization code (Sabrina). MCNP is then run to estimate the dose to the embryo/fetus and the exposure to skin entrance (ESE) for the beam being modeled. The actual ESE for the beam is then measured with ion chambers and the fetal dose is determined from the MCNP supplied ratio of ESE to fetal dose. Runs are made for each type of imaging and the doses are summed for the total fetal dose. For most procedures, the method can provide an estimate of the fetal dose within one day of the study. The method can also be used to prospectively model a study in order to choose imaging sequences that will minimize fetal dose.

  12. 76 FR 5319 - Regulation of Fuel and Fuel Additives: Alternative Test Method for Olefins in Gasoline

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-31

    ... AGENCY 40 CFR Part 80 RIN 2060-AP17 Regulation of Fuel and Fuel Additives: Alternative Test Method for... correlated to the fuel parameter's respective EPA designated test method. These alternative test methods are... sections 114(a) and 301(a) of the CAA. Regulation of Fuel and Fuel Additives: Alternative Test Method...

  13. Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation

    PubMed Central

    Anderson, Catherine; Malambo, Dennis Hanjalika; Gonzalez Perez, Maria Eliette; Nobela, Happiness Ngwanamoseka; de Pooter, Lobke; Spit, Jan; Hooijmans, Christine Maria; van de Vossenberg, Jack; Greya, Wilson; Thole, Bernard; van Lier, Jules B.; Brdjanovic, Damir

    2015-01-01

    In this research, three faecal sludge sanitizing methods—lactic acid fermentation, urea treatment and lime treatment—were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m3 of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment. PMID:26528995

  14. Objective method to report planner-independent skin/rib maximal dose in balloon-based high dose rate (HDR) brachytherapy for breast cancer

    SciTech Connect

    Kim, Yongbok; Trombetta, Mark G.

    2011-04-15

    Purpose: An objective method was proposed and compared with a manual selection method to determine planner-independent skin and rib maximal dose in balloon-based high dose rate (HDR) brachytherapy planning. Methods: The maximal dose to skin and rib was objectively extracted from a dose volume histogram (DVH) of skin and rib volumes. A virtual skin volume was produced by expanding the skin surface in three dimensions (3D) external to the breast with a certain thickness in the planning computed tomography (CT) images. Therefore, the maximal dose to this volume occurs on the skin surface the same with a conventional manual selection method. The rib was also delineated in the planning CT images and its maximal dose was extracted from its DVH. The absolute (Abdiff=|D{sub max}{sup Man}-D{sub max}{sup DVH}|) and relative (Rediff[%]=100x(|D{sub max}{sup Man}-D{sub max}{sup DVH}|)/D{sub max}{sup DVH}) maximal skin and rib dose differences between the manual selection method (D{sub max}{sup Man}) and the objective method (D{sub max}{sup DVH}) were measured for 50 balloon-based HDR (25 MammoSite and 25 Contura) patients. Results: The average{+-}standard deviation of maximal dose difference was 1.67%{+-}1.69% of the prescribed dose (PD). No statistical difference was observed between MammoSite and Contura patients for both Abdiff and Rediff[%] values. However, a statistically significant difference (p value <0.0001) was observed in maximal rib dose difference compared with maximal skin dose difference for both Abdiff (2.30%{+-}1.71% vs 1.05%{+-}1.43%) and Rediff[%] (2.32%{+-}1.79% vs 1.21%{+-}1.41%). In general, rib has a more irregular contour and it is more proximally located to the balloon for 50 HDR patients. Due to the inverse square law factor, more dose difference was observed in higher dose range (D{sub max}>90%) compared with lower dose range (D{sub max}<90%): 2.16%{+-}1.93% vs 1.19%{+-}1.25% with p value of 0.0049. However, the Rediff[%] analysis eliminated the

  15. A Novel Method for the Evaluation of Uncertainty in Dose-Volume Histogram Computation

    SciTech Connect

    Henriquez, Francisco Cutanda M.Sc. Castrillon, Silvia Vargas

    2008-03-15

    Purpose: Dose-volume histograms (DVHs) are a useful tool in state-of-the-art radiotherapy treatment planning, and it is essential to recognize their limitations. Even after a specific dose-calculation model is optimized, dose distributions computed by using treatment-planning systems are affected by several sources of uncertainty, such as algorithm limitations, measurement uncertainty in the data used to model the beam, and residual differences between measured and computed dose. This report presents a novel method to take them into account. Methods and Materials: To take into account the effect of associated uncertainties, a probabilistic approach using a new kind of histogram, a dose-expected volume histogram, is introduced. The expected value of the volume in the region of interest receiving an absorbed dose equal to or greater than a certain value is found by using the probability distribution of the dose at each point. A rectangular probability distribution is assumed for this point dose, and a formulation that accounts for uncertainties associated with point dose is presented for practical computations. Results: This method is applied to a set of DVHs for different regions of interest, including 6 brain patients, 8 lung patients, 8 pelvis patients, and 6 prostate patients planned for intensity-modulated radiation therapy. Conclusions: Results show a greater effect on planning target volume coverage than in organs at risk. In cases of steep DVH gradients, such as planning target volumes, this new method shows the largest differences with the corresponding DVH; thus, the effect of the uncertainty is larger.

  16. High-order noise analysis for low dose iterative image reconstruction methods: ASIR, IRIS, and MBAI

    NASA Astrophysics Data System (ADS)

    Do, Synho; Singh, Sarabjeet; Kalra, Mannudeep K.; Karl, W. Clem; Brady, Thomas J.; Pien, Homer

    2011-03-01

    Iterative reconstruction techniques (IRTs) has been shown to suppress noise significantly in low dose CT imaging. However, medical doctors hesitate to accept this new technology because visual impression of IRT images are different from full-dose filtered back-projection (FBP) images. Most common noise measurements such as the mean and standard deviation of homogeneous region in the image that do not provide sufficient characterization of noise statistics when probability density function becomes non-Gaussian. In this study, we measure L-moments of intensity values of images acquired at 10% of normal dose and reconstructed by IRT methods of two state-of-art clinical scanners (i.e., GE HDCT and Siemens DSCT flash) by keeping dosage level identical to each other. The high- and low-dose scans (i.e., 10% of high dose) were acquired from each scanner and L-moments of noise patches were calculated for the comparison.

  17. Deterministic absorbed dose estimation in computed tomography using a discrete ordinates method

    SciTech Connect

    Norris, Edward T.; Liu, Xin; Hsieh, Jiang

    2015-07-15

    Purpose: Organ dose estimation for a patient undergoing computed tomography (CT) scanning is very important. Although Monte Carlo methods are considered gold-standard in patient dose estimation, the computation time required is formidable for routine clinical calculations. Here, the authors instigate a deterministic method for estimating an absorbed dose more efficiently. Methods: Compared with current Monte Carlo methods, a more efficient approach to estimating the absorbed dose is to solve the linear Boltzmann equation numerically. In this study, an axial CT scan was modeled with a software package, Denovo, which solved the linear Boltzmann equation using the discrete ordinates method. The CT scanning configuration included 16 x-ray source positions, beam collimators, flat filters, and bowtie filters. The phantom was the standard 32 cm CT dose index (CTDI) phantom. Four different Denovo simulations were performed with different simulation parameters, including the number of quadrature sets and the order of Legendre polynomial expansions. A Monte Carlo simulation was also performed for benchmarking the Denovo simulations. A quantitative comparison was made of the simulation results obtained by the Denovo and the Monte Carlo methods. Results: The difference in the simulation results of the discrete ordinates method and those of the Monte Carlo methods was found to be small, with a root-mean-square difference of around 2.4%. It was found that the discrete ordinates method, with a higher order of Legendre polynomial expansions, underestimated the absorbed dose near the center of the phantom (i.e., low dose region). Simulations of the quadrature set 8 and the first order of the Legendre polynomial expansions proved to be the most efficient computation method in the authors’ study. The single-thread computation time of the deterministic simulation of the quadrature set 8 and the first order of the Legendre polynomial expansions was 21 min on a personal computer

  18. Dose-additivity modeling for acute and repeated exposure to a mixture of N-methycarbamate Pesticides

    EPA Science Inventory

    The toxicity of N-methylcarbamate pesticides is attributed to the reversible inhibition of cholinesterase (ChE) enzymes in the central and peripheral nervous system. The inhibition of ChE following a single exposure to this class of pesticides has been modeled using a dose-additi...

  19. A method of dose reconstruction for moving targets compatible with dynamic treatments

    SciTech Connect

    Rugaard Poulsen, Per; Lykkegaard Schmidt, Mai; Keall, Paul; Schjodt Worm, Esben; Fledelius, Walther; Hoffmann, Lone

    2012-10-15

    Purpose: To develop a method that allows a commercial treatment planning system (TPS) to perform accurate dose reconstruction for rigidly moving targets and to validate the method in phantom measurements for a range of treatments including intensity modulated radiation therapy (IMRT), volumetric arc therapy (VMAT), and dynamic multileaf collimator (DMLC) tracking. Methods: An in-house computer program was developed to manipulate Dicom treatment plans exported from a TPS (Eclipse, Varian Medical Systems) such that target motion during treatment delivery was incorporated into the plans. For each treatment, a motion including plan was generated by dividing the intratreatment target motion into 1 mm position bins and construct sub-beams that represented the parts of the treatment that were delivered, while the target was located within each position bin. For each sub-beam, the target shift was modeled by a corresponding isocenter shift. The motion incorporating Dicom plans were reimported into the TPS, where dose calculation resulted in motion including target dose distributions. For experimental validation of the dose reconstruction a thorax phantom with a moveable lung equivalent rod with a tumor insert of solid water was first CT scanned. The tumor insert was delineated as a gross tumor volume (GTV), and a planning target volume (PTV) was formed by adding margins. A conformal plan, two IMRT plans (step-and-shoot and sliding windows), and a VMAT plan were generated giving minimum target doses of 95% (GTV) and 67% (PTV) of the prescription dose (3 Gy). Two conformal fields with MLC leaves perpendicular and parallel to the tumor motion, respectively, were generated for DMLC tracking. All treatment plans were delivered to the thorax phantom without tumor motion and with a sinusoidal tumor motion. The two conformal fields were delivered with and without portal image guided DMLC tracking based on an embedded gold marker. The target dose distribution was measured with a

  20. Simplified estimation method for dose distributions around field junctions in proton craniospinal irradiation.

    PubMed

    Yamashita, Haruo; Kase, Yuki; Murayama, Shigeyuki

    2017-03-01

    In radiotherapy involving craniospinal irradiation (CSI), field junctions of therapeutic beams are necessary, because a CSI target is generally several times larger than the maximum field size of the beams. The purpose of this study was to develop a simplified method for estimating dose uniformity around the field junctions in proton CSI. We estimated the dose profiles around the field junctions of proton beams using a simplified field-junction model, in which partial lateral dose distributions around the field edge were assumed to be approximated using the error function. We measured the lateral dose distributions of the proton beams planned for the CSI treatment using a two-dimensional (2D) ionization chamber array. Although dose hot spots and cold spots tend to be underestimated by a chamber array because of the partial volume effect of the sensitive volume and discrete chamber positions, the model estimation results were fairly consistent with the measurements obtained using a 2D chamber array subjected to CSI-simulated serial irradiation. The simplified junction model enabled us to estimate the dose distributions and dependence of the setup position gap on the dose uniformity around the field junctions on the basis of the field-by-field dose profiles measured using the 2D chamber array.

  1. Addition of a third field significantly increases dose to the brachial plexus for patients undergoing tangential whole-breast therapy after lumpectomy

    SciTech Connect

    Stanic, Sinisa; Mathai, Mathew; Mayadev, Jyoti S.; Do, Ly V.; Purdy, James A.; Chen, Allen M.

    2012-07-01

    Our goal was to evaluate brachial plexus (BP) dose with and without the use of supraclavicular (SCL) irradiation in patients undergoing breast-conserving therapy with whole-breast radiation therapy (RT) after lumpectomy. Using the standardized Radiation Therapy Oncology Group (RTOG)-endorsed guidelines delineation, we contoured the BP for 10 postlumpectomy breast cancer patients. The radiation dose to the whole breast was 50.4 Gy using tangential fields in 1.8-Gy fractions, followed by a conedown to the operative bed using electrons (10 Gy). The prescription dose to the SCL field was 50.4 Gy, delivered to 3-cm depth. The mean BP volume was 14.5 {+-} 1.5 cm{sup 3}. With tangential fields alone, the median mean dose to the BP was 0.57 Gy, the median maximum dose was 1.93 Gy, and the irradiated volume of the BP receiving 40, 45, and 50 Gy was 0%. When the third (SCL field) was added, the dose to the BP was significantly increased (P = .01): the median mean dose to the BP was 40.60 Gy, and the median maximum dose was 52.22 Gy. With 3-field RT, the median irradiated volume of the BP receiving 40, 45, and 50 Gy was 83.5%, 68.5%, and 24.6%, respectively. The addition of the SCL field significantly increases dose to the BP. The possibility of increasing the risk of BP morbidity should be considered in the context of clinical decision making.

  2. A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

    SciTech Connect

    Zhang, Da; Li, Xinhua; Liu, Bob; Gao, Yiming; Xu, X. George

    2013-08-15

    Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future.Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations.Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated

  3. Dose computation in conformal radiation therapy including geometric uncertainties: Methods and clinical implications

    NASA Astrophysics Data System (ADS)

    Rosu, Mihaela

    The aim of any radiotherapy is to tailor the tumoricidal radiation dose to the target volume and to deliver as little radiation dose as possible to all other normal tissues. However, the motion and deformation induced in human tissue by ventilatory motion is a major issue, as standard practice usually uses only one computed tomography (CT) scan (and hence one instance of the patient's anatomy) for treatment planning. The interfraction movement that occurs due to physiological processes over time scales shorter than the delivery of one treatment fraction leads to differences between the planned and delivered dose distributions. Due to the influence of these differences on tumors and normal tissues, the tumor control probabilities and normal tissue complication probabilities are likely to be impacted upon in the face of organ motion. In this thesis we apply several methods to compute dose distributions that include the effects of the treatment geometric uncertainties by using the time-varying anatomical information as an alternative to the conventional Planning Target Volume (PTV) approach. The proposed methods depend on the model used to describe the patient's anatomy. The dose and fluence convolution approaches for rigid organ motion are discussed first, with application to liver tumors and the rigid component of the lung tumor movements. For non-rigid behavior a dose reconstruction method that allows the accumulation of the dose to the deforming anatomy is introduced, and applied for lung tumor treatments. Furthermore, we apply the cumulative dose approach to investigate how much information regarding the deforming patient anatomy is needed at the time of treatment planning for tumors located in thorax. The results are evaluated from a clinical perspective. All dose calculations are performed using a Monte Carlo based algorithm to ensure more realistic and more accurate handling of tissue heterogeneities---of particular importance in lung cancer treatment planning.

  4. Addition of long-acting beta2-agonists to inhaled corticosteroids versus same dose inhaled corticosteroids for chronic asthma in adults and children

    PubMed Central

    Ducharme, Francine M; Ni Chroinin, Muireann; Greenstone, Ilana; Lasserson, Toby J

    2014-01-01

    Background Long-acting inhaled ß2-adrenergic agonists (LABAs) are recommended as ’add-on’ medication to inhaled corticosteroids (ICS) in the maintenance therapy of asthmatic adults and children aged two years and above. Objectives To quantify in asthmatic patients the safety and efficacy of the addition of LABAs to ICS in patients insufficiently controlled on ICS alone. Search methods We identified randomised controlled trials (RCTs) through electronic database searches (the Cochrane Airways Group Specialised Register, MEDLINE, EMBASE and CINAHL), bibliographies of RCTs and correspondence with manufacturers until May 2008. Selection criteria We included RCTs if they compared the addition of inhaled LABAs versus placebo to the same dose of ICS in children aged two years and above and in adults. Data collection and analysis Two review authors independently assessed studies for methodological quality and extracted data. We obtained confirmation from the trialists when possible. The primary endpoint was the relative risk (RR) of asthma exacerbations requiring rescue oral corticosteroids. Secondary endpoints included pulmonary function tests (PFTs), rescue beta2-agonist use, symptoms, withdrawals and adverse events. Main results Seventy-seven studies met the entry criteria and randomised 21,248 participants (4625 children and 16,623 adults). Participants were generally symptomatic at baseline with moderate airway obstruction despite their current ICS regimen. Formoterol or salmeterol were most frequently added to low-dose ICS (200 to 400 μg/day of beclomethasone (BDP) or equivalent) in 49% of the studies. The addition of a daily LABA to ICS reduced the risk of exacerbations requiring oral steroids by 23% from 15% to 11% (RR 0.77, 95% CI 0.68 to 0.87, 28 studies, 6808 participants). The number needed to treat with the addition of LABA to prevent one use of rescue oral corticosteroids is 41 (29, 72), although the event rates in the ICS groups varied between 0% and

  5. Additive Methods for Prediction of Thermochemical Properties. The Laidler Method Revisited. 1. Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Leal, Joa˜O. Paulo

    2006-03-01

    A new parameterization of the Laidler method for estimation of atomization enthalpies and standard enthalpies of formation at 298.15 K for several families of hydrocarbons (alkanes, alkenes, alkynes, polyenes, poly-ynes, alkyl radicals, cycloalkanes, cycloalkenes, benzene derivatives, and polyaromatics) is presented. A total of 200 compounds (164 for liquid phase) are used for the calculation of the parameters. Comparison between the experimental values and those calculated using the group additive scheme led to an average difference of 1.28 kJṡmol-1 for the gas phase enthalpy of formation (excluding the polyaromatic compounds) and of 1.38 kJṡmol-1 for the liquid phase enthalpy of formation. The data base used appears to be essentially error free, but for some compounds (e.g., 2,2,4-trimethyl-pentane, with the highest deviation among all compounds except the polyaromatic ones) the experimental values might need a reevaluation. An Excel worksheet is provided to simplify the calculation of enthalpies of formation and atomization enthalpies based on the Laidler terms defined in this paper.

  6. TH-C-BRD-02: Analytical Modeling and Dose Calculation Method for Asymmetric Proton Pencil Beams

    SciTech Connect

    Gelover, E; Wang, D; Hill, P; Flynn, R; Hyer, D

    2014-06-15

    Purpose: A dynamic collimation system (DCS), which consists of two pairs of orthogonal trimmer blades driven by linear motors has been proposed to decrease the lateral penumbra in pencil beam scanning proton therapy. The DCS reduces lateral penumbra by intercepting the proton pencil beam near the lateral boundary of the target in the beam's eye view. The resultant trimmed pencil beams are asymmetric and laterally shifted, and therefore existing pencil beam dose calculation algorithms are not capable of trimmed beam dose calculations. This work develops a method to model and compute dose from trimmed pencil beams when using the DCS. Methods: MCNPX simulations were used to determine the dose distributions expected from various trimmer configurations using the DCS. Using these data, the lateral distribution for individual beamlets was modeled with a 2D asymmetric Gaussian function. The integral depth dose (IDD) of each configuration was also modeled by combining the IDD of an untrimmed pencil beam with a linear correction factor. The convolution of these two terms, along with the Highland approximation to account for lateral growth of the beam along the depth direction, allows a trimmed pencil beam dose distribution to be analytically generated. The algorithm was validated by computing dose for a single energy layer 5×5 cm{sup 2} treatment field, defined by the trimmers, using both the proposed method and MCNPX beamlets. Results: The Gaussian modeled asymmetric lateral profiles along the principal axes match the MCNPX data very well (R{sup 2}≥0.95 at the depth of the Bragg peak). For the 5×5 cm{sup 2} treatment plan created with both the modeled and MCNPX pencil beams, the passing rate of the 3D gamma test was 98% using a standard threshold of 3%/3 mm. Conclusion: An analytical method capable of accurately computing asymmetric pencil beam dose when using the DCS has been developed.

  7. A method for converting dose-to-medium to dose-to-tissue in Monte Carlo studies of gold nanoparticle-enhanced radiotherapy

    NASA Astrophysics Data System (ADS)

    Koger, B.; Kirkby, C.

    2016-03-01

    Gold nanoparticles (GNPs) have shown potential in recent years as a means of therapeutic dose enhancement in radiation therapy. However, a major challenge in moving towards clinical implementation is the exact characterisation of the dose enhancement they provide. Monte Carlo studies attempt to explore this property, but they often face computational limitations when examining macroscopic scenarios. In this study, a method of converting dose from macroscopic simulations, where the medium is defined as a mixture containing both gold and tissue components, to a mean dose-to-tissue on a microscopic scale was established. Monte Carlo simulations were run for both explicitly-modeled GNPs in tissue and a homogeneous mixture of tissue and gold. A dose ratio was obtained for the conversion of dose scored in a mixture medium to dose-to-tissue in each case. Dose ratios varied from 0.69 to 1.04 for photon sources and 0.97 to 1.03 for electron sources. The dose ratio is highly dependent on the source energy as well as GNP diameter and concentration, though this effect is less pronounced for electron sources. By appropriately weighting the monoenergetic dose ratios obtained, the dose ratio for any arbitrary spectrum can be determined. This allows complex scenarios to be modeled accurately without explicitly simulating each individual GNP.

  8. A method for converting dose-to-medium to dose-to-tissue in Monte Carlo studies of gold nanoparticle-enhanced radiotherapy.

    PubMed

    Koger, B; Kirkby, C

    2016-03-07

    Gold nanoparticles (GNPs) have shown potential in recent years as a means of therapeutic dose enhancement in radiation therapy. However, a major challenge in moving towards clinical implementation is the exact characterisation of the dose enhancement they provide. Monte Carlo studies attempt to explore this property, but they often face computational limitations when examining macroscopic scenarios. In this study, a method of converting dose from macroscopic simulations, where the medium is defined as a mixture containing both gold and tissue components, to a mean dose-to-tissue on a microscopic scale was established. Monte Carlo simulations were run for both explicitly-modeled GNPs in tissue and a homogeneous mixture of tissue and gold. A dose ratio was obtained for the conversion of dose scored in a mixture medium to dose-to-tissue in each case. Dose ratios varied from 0.69 to 1.04 for photon sources and 0.97 to 1.03 for electron sources. The dose ratio is highly dependent on the source energy as well as GNP diameter and concentration, though this effect is less pronounced for electron sources. By appropriately weighting the monoenergetic dose ratios obtained, the dose ratio for any arbitrary spectrum can be determined. This allows complex scenarios to be modeled accurately without explicitly simulating each individual GNP.

  9. Method for Fast CT/SPECT-Based 3D Monte Carlo Absorbed Dose Computations in Internal Emitter Therapy

    PubMed Central

    Wilderman, S. J.; Dewaraja, Y. K.

    2010-01-01

    The DPM (Dose Planning Method) Monte Carlo electron and photon transport program, designed for fast computation of radiation absorbed dose in external beam radiotherapy, has been adapted to the calculation of absorbed dose in patient-specific internal emitter therapy. Because both its photon and electron transport mechanics algorithms have been optimized for fast computation in 3D voxelized geometries (in particular, those derived from CT scans), DPM is perfectly suited for performing patient-specific absorbed dose calculations in internal emitter therapy. In the updated version of DPM developed for the current work, the necessary inputs are a patient CT image, a registered SPECT image, and any number of registered masks defining regions of interest. DPM has been benchmarked for internal emitter therapy applications by comparing computed absorption fractions for a variety of organs using a Zubal phantom with reference results from the Medical Internal Radionuclide Dose (MIRD) Committee standards. In addition, the β decay source algorithm and the photon tracking algorithm of DPM have been further benchmarked by comparison to experimental data. This paper presents a description of the program, the results of the benchmark studies, and some sample computations using patient data from radioimmunotherapy studies using 131I. PMID:20305792

  10. A simulation study of methods for selecting subgroup-specific doses in phase 1 trials.

    PubMed

    Morita, Satoshi; Thall, Peter F; Takeda, Kentaro

    2017-03-01

    Patient heterogeneity may complicate dose-finding in phase 1 clinical trials if the dose-toxicity curves differ between subgroups. Conducting separate trials within subgroups may lead to infeasibly small sample sizes in subgroups having low prevalence. Alternatively,it is not obvious how to conduct a single trial while accounting for heterogeneity. To address this problem,we consider a generalization of the continual reassessment method on the basis of a hierarchical Bayesian dose-toxicity model that borrows strength between subgroups under the assumption that the subgroups are exchangeable. We evaluate a design using this model that includes subgroup-specific dose selection and safety rules. A simulation study is presented that includes comparison of this method to 3 alternative approaches,on the basis of nonhierarchical models,that make different types of assumptions about within-subgroup dose-toxicity curves. The simulations show that the hierarchical model-based method is recommended in settings where the dose-toxicity curves are exchangeable between subgroups. We present practical guidelines for application and provide computer programs for trial simulation and conduct.

  11. A Simulation Study of Methods for Selecting Subgroup-Specific Doses in Phase I Trials

    PubMed Central

    Morita, Satoshi; Thall, Peter F.; Takeda, Kentaro

    2016-01-01

    Summary Patient heterogeneity may complicate dose-finding in phase I clinical trials if the dose-toxicity curves differ between subgroups. Conducting separate trials within subgroups may lead to infeasibly small sample sizes in subgroups having low prevalence. Alternatively, it is not obvious how to conduct a single trial while accounting for heterogeneity. To address this problem, we consider a generalization of the continual reassessment method (O’Quigley, et al., 1990) based on a hierarchical Bayesian dose-toxicity model that borrows strength between subgroups under the assumption that the subgroups are exchangeable. We evaluate a design using this model that includes subgroup-specific dose selection and safety rules. A simulation study is presented that includes comparison of this method to three alternative approaches, based on non-hierarchical models, that make different types of assumptions about within-subgroup dose-toxicity curves. The simulations show that the hierarchical model-based method is recommended in settings where the dose-toxicity curves are exchangeable between subgroups. We present practical guidelines for application, and provide computer programs for trial simulation and conduct. PMID:28111916

  12. [Estimation of the committed effective dose of radioactive cesium and potassium by the market basket method].

    PubMed

    Tsutsumi, Tomoaki; Nabeshi, Hiromi; Ikarashi, Atsuko; Hachisuka, Akiko; Matsuda, Rieko

    2013-01-01

    The Tokyo Electric Power Company's Fukushima Daiichi nuclear power plant disaster after the Great East Japan Earthquake has caused radioactive contamination in food. Using the market basket method, total diet samples in Tokyo, Miyagi prefecture and Fukushima prefecture were analyzed for cesium-134 and -137 (radioactive cesium) and naturally occurring potassium-40 (radioactive potassium) in order to estimate the committed effective doses of these radioactive materials from food. Doses were calculated on the assumption that "not detected" corresponded to zero or to half the limit of detection (values in brackets). The estimated doses of radioactive cesium in Tokyo, Miyagi and Fukushima were 0.0021 (0.0024), 0.017 (0.018) and 0.019 (0.019) mSv/year, respectively. Although the doses in Miyagi and Fukushima were more than 8 times the dose in Tokyo, they were significantly lower than the maximum permissible dose (1 mSv/year) determined by the Ministry of Health, Labour and Welfare, Japan. The estimated doses of naturally occurring radioactive potassium in these areas were in the range of 0.17-0.20 (0.18-0.20) mSv/year, and there were no significant differences between the areas.

  13. 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.

  14. A fast analytic dose calculation method for arc treatments for kilovoltage small animal irradiators.

    PubMed

    Marco-Rius, I; Wack, L; Tsiamas, P; Tryggestad, E; Berbeco, R; Hesser, J; Zygmanski, P

    2013-09-01

    Arc treatments require calculation of dose for collections of discrete gantry angles. The sampling of angles must balance between short computation time of small angle sets and the better calculation reliability of large sets. In this paper, an analytical formula is presented that allows calculation of dose delivered during continuous rotation of the gantry. The formula holds valid for continuous short arcs of up to about 30° and is derived by integrating a dose formula over gantry angles within a small angle approximation. Doses for longer arcs may be obtained in terms of doses for shorter arcs. The formula is derived with an empirical beam model in water and extended to inhomogeneous media. It is validated with experimental data obtained by applying arc treatment using kV small animal irradiator to a phantom of solid water and lung-equivalent material. The results are a promising step towards efficient 3D dose calculation and inverse planning purposes. In principle, this method also applies to VMAT dose calculation and optimization but requires extensions.

  15. Comparing measurement-derived (3DVH) and machine log file-derived dose reconstruction methods for VMAT QA in patient geometries.

    PubMed

    Tyagi, Neelam; Yang, Kai; Yan, Di

    2014-07-08

    The purpose of this study was to compare the measurement-derived (3DVH) dose reconstruction method with machine log file-derived dose reconstruction method in patient geometries for VMAT delivery. A total of ten patient plans were selected from a regular fractionation plan to complex SBRT plans. Treatment sites in the lung and abdomen were chosen to explore the effects of tissue heterogeneity on the respective dose reconstruction algorithms. Single- and multiple-arc VMAT plans were generated to achieve the desired target objectives. Delivered plan in the patient geometry was reconstructed by using ArcCHECK Planned Dose Perturbation (ACPDP) within 3DVH software, and by converting the machine log file to Pinnacle3 9.0 treatment plan format and recalculating dose with CVSP algorithm. In addition, delivered gantry angles between machine log file and 3DVH 4D measurement were also compared to evaluate the accuracy of the virtual inclinometer within the 3DVH. Measured ion chamber and 3DVH-derived isocenter dose agreed with planned dose within 0.4% ± 1.2% and -1.0% ± 1.6%, respectively. 3D gamma analysis showed greater than 98% between log files and 3DVH reconstructed dose. Machine log file reconstructed doses and TPS dose agreed to within 2% in PTV and OARs over the entire treatment. 3DVH reconstructed dose showed an average maximum dose difference of 3% ± 1.2% in PTV, and an average mean difference of -4.5% ± 10.5% in OAR doses. The average virtual inclinometer error (VIE) was -0.65° ± 1.6° for all patients, with a maximum error of -5.16° ± 4.54° for an SRS case. The time averaged VIE was within 1°-2°, and did not have a large impact on the overall accuracy of the estimated patient dose from ACPDP algorithm. In this study, we have compared two independent dose reconstruction methods for VMAT QA. Both methods are capable of taking into account the measurement and delivery parameter discrepancy, and display the delivered dose in CT patient geometry rather than

  16. Using the Monte Carlo method for assessing the tissue and organ doses of patients in dental radiography

    NASA Astrophysics Data System (ADS)

    Makarevich, K. O.; Minenko, V. F.; Verenich, K. A.; Kuten, S. A.

    2016-05-01

    This work is dedicated to modeling dental radiographic examinations to assess the absorbed doses of patients and effective doses. For simulating X-ray spectra, the TASMIP empirical model is used. Doses are assessed on the basis of the Monte Carlo method by using MCNP code for voxel phantoms of ICRP. The results of the assessment of doses to individual organs and effective doses for different types of dental examinations and features of X-ray tube are presented.

  17. Dose Addition Models Based on Biologically Relevant Reductions in Fetal Testosterone Accurately Predict Postnatal Reproductive Tract Alterations by a Phthalate Mixture in Rats

    PubMed Central

    Howdeshell, Kembra L.; Rider, Cynthia V.; Wilson, Vickie S.; Furr, Johnathan R.; Lambright, Christy R.; Gray, L. Earl

    2015-01-01

    Challenges in cumulative risk assessment of anti-androgenic phthalate mixtures include a lack of data on all the individual phthalates and difficulty determining the biological relevance of reduction in fetal testosterone (T) on postnatal development. The objectives of the current study were 2-fold: (1) to test whether a mixture model of dose addition based on the fetal T production data of individual phthalates would predict the effects of a 5 phthalate mixture on androgen-sensitive postnatal male reproductive tract development, and (2) to determine the biological relevance of the reductions in fetal T to induce abnormal postnatal reproductive tract development using data from the mixture study. We administered a dose range of the mixture (60, 40, 20, 10, and 5% of the top dose used in the previous fetal T production study consisting of 300 mg/kg per chemical of benzyl butyl (BBP), di(n)butyl (DBP), diethyl hexyl phthalate (DEHP), di-isobutyl phthalate (DiBP), and 100 mg dipentyl (DPP) phthalate/kg; the individual phthalates were present in equipotent doses based on their ability to reduce fetal T production) via gavage to Sprague Dawley rat dams on GD8-postnatal day 3. We compared observed mixture responses to predictions of dose addition based on the previously published potencies of the individual phthalates to reduce fetal T production relative to a reference chemical and published postnatal data for the reference chemical (called DAref). In addition, we predicted DA (called DAall) and response addition (RA) based on logistic regression analysis of all 5 individual phthalates when complete data were available. DA ref and DA all accurately predicted the observed mixture effect for 11 of 14 endpoints. Furthermore, reproductive tract malformations were seen in 17–100% of F1 males when fetal T production was reduced by about 25–72%, respectively. PMID:26350170

  18. New method of proportional counter feedback biasing for wide-range radiation dose-rate monitors

    SciTech Connect

    Kopp, M.K.; Valentine, K.H.; Guerrant, G.C.; Manning, F.W.

    1984-01-01

    A prototypic wide-range radiation dose-rate monitor for civil defense applications has been developed and tested. The specified dose-rate range (0 to 500 R/h) was displayed on a single readout scale by using feedback-controlled biasing of a proportional counter. This new method is based on controlling the avalanche multiplication factor (gas gain) of the counter by varying its bias voltage in response to its measured output current (i.e., detected dose rate). The counter output current varies between 0 and 1.5 nA in a quasi-logarithmic response to dose rates between 0 and 500 R/h. The corresponding values of gas gain and bias voltage range from 1 to 300 and 200 to 1900 V respectively.

  19. Comparison of Methods to Reduce Dose to Swallowing-Related Structures in Head and Neck Cancer

    SciTech Connect

    Caudell, Jimmy J.; Burnett, Omer L.; Schaner, Philip E.; Bonner, James A.; Duan Jun

    2010-06-01

    Introduction: Emerging data suggest that reduction of dose to the larynx and pharyngeal constrictor may lower the risk of swallowing complications such as long-term gastrostomy dependence and aspiration. Organ avoidance becomes difficult when the primary tumor or involved nodes are present at the level of the larynx. Materials and Methods: Fifteen patients with Stage III-IV squamous cell carcinoma of the head and neck with high-dose target volume at the level of the larynx (but not involving the glottic larynx) were planned with whole-field IMRT (WF-IMRT), as well as a low anterior neck field dynamically matched to an IMRT plan (D-SCLV). Plans were compared with respect to coverage of targets and sparing of normal tissues including the larynx, inferior pharyngeal constrictor (IPC), parotid, and cord. Results: There was no significant difference between the two techniques in coverage of the high- or intermediate-dose planning target volumes (PTVs). Coverage of the elective nodal PTV was inferior with the D-SCLV technique, with a mean of 96.5% vs. 86.3% of the volume receiving the prescription dose (p = 0.001) compared with WF-IMRT plans. However, the D-SCLV technique significantly reduced mean dose to the larynx (43.7 vs. 46.7 Gy, p = 0.05) and IPC (39.1 vs. 46.1 Gy, p = 0.002). There was no significant difference in dose to the parotid or cord. Conclusion: Given the steep dose responses seen in studies examining the association between swallowing toxicity and dose to the larynx and IPC, dose reductions using the D-SCLV technique may be clinically significant.

  20. Radioactivity in food and the environment: calculations of UK radiation doses using integrated assessment methods.

    PubMed

    Camplin, W C; Brownless, G P; Round, G D; Winpenny, K; Hunt, G J

    2002-12-01

    A new method for estimating radiation doses to UK critical groups is proposed for discussion. Amongst others, the Food Standards Agency (FSA) and the Scottish Environment Protection Agency (SEPA) undertake surveillance of UK food and the environment as a check on the effect of discharges of radioactive wastes. Discharges in gaseous and liquid form are made under authorisation by the Environment Agency and SEPA under powers in the Radioactive Substance Act. Results of surveillance by the FSA and SEPA are published in the Radioactivity in Food and the Environment (RIFE) report series. In these reports, doses to critical groups are normally estimated separately for gaseous and liquid discharge pathways. Simple summation of these doses would tend to overestimate doses actually received. Three different methods of combining the effects of both types of discharge in an integrated assessment are considered and ranked according to their ease of application, transparency, scientific rigour and presentational issues. A single integrated assessment method is then chosen for further study. Doses are calculated for surveillance data for the calendar year 2000 and compared with those from the existing RIFE method.

  1. An easy method to account for light scattering dose dependence in radiochromic films

    SciTech Connect

    Miras, Hector; Arrans, Rafael

    2009-09-15

    Purpose: To date no detector can offer the unbeatable characteristics of film dosimetry in terms of spatial resolution and this is why it has been chosen by many institutions for treatment verification and, in that respect, radiochromic films are becoming increasingly popular due to their advantageous properties. It is the aim of this work to suggest an easy method to overcome one of the drawbacks in radiochromic film dosimetry associated with the scanning device, namely, the non-uniform dose dependent response, mainly due to the light scattering effect. Methods: The suggested procedure consists of building four correction matrices by sequentially scanning one, two, three, and four unexposed blank films. The color level of these four matrices is compatible with four points in the calibration curve dose range. Therefore, the dose dependent correction to the scanned irradiated film will be obtained by interpolating between the four correction matrices. Results: The validity of the suggested method is checked against an ion chamber 2D array. The use of the proposed flattening correction improves considerably the dose agreement when compared with the cases in which no correction is applied. Conclusions: The method showed to be fast and easy and practically overcomes the dependence on the dose of light scattering of flatbed scanners.

  2. 40 CFR 80.8 - Sampling methods for gasoline, diesel fuel, fuel additives, and renewable fuels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... fuel, fuel additives, and renewable fuels. 80.8 Section 80.8 Protection of Environment ENVIRONMENTAL... Provisions § 80.8 Sampling methods for gasoline, diesel fuel, fuel additives, and renewable fuels. The..., blendstocks, fuel additives and renewable fuels for purposes of determining compliance with the...

  3. Perinatal BPA exposure alters body weight and composition in a dose specific and sex specific manner: The addition of peripubertal exposure exacerbates adverse effects in female mice.

    PubMed

    Rubin, Beverly S; Paranjpe, Maneesha; DaFonte, Tracey; Schaeberle, Cheryl; Soto, Ana M; Obin, Martin; Greenberg, Andrew S

    2017-03-01

    Body weight (BW) and body composition were examined in CD-1 mice exposed perinatally or perinatally and peripubertally to 0, 0.25, 2.5, 25, or 250μg BPA/kg BW/day. Our goal was to identify the BPA dose (s) and the exposure window(s) that increased BW and adiposity, and to assess potential sex differences in this response. Both perinatal exposure alone and perinatal plus peripubertal exposure to environmentally relevant levels of BPA resulted in lasting effects on body weight and body composition. The effects were dose specific and sex specific and were influenced by the precise window of BPA exposure. The addition of peripubertal BPA exposure following the initial perinatal exposure exacerbated adverse effects in the females but appeared to reduce differences in body weight and body composition between control and BPA exposed males. Some effects of BPA on body weight and body composition showed a non-linear dose response.

  4. A patient-specific Monte Carlo dose-calculation method for photon beams.

    PubMed

    Wang, L; Chui, C S; Lovelock, M

    1998-06-01

    A patient-specific, CT-based, Monte Carlo dose-calculation method for photon beams has been developed to correctly account for inhomogeneity in the patient. The method employs the EGS4 system to sample the interaction of radiation in the medium. CT images are used to describe the patient geometry and to determine the density and atomic number in each voxel. The user code (MCPAT) provides the data describing the incident beams, and performs geometry checking and energy scoring in patient CT images. Several variance reduction techniques have been implemented to improve the computation efficiency. The method was verified with measured data and other calculations, both in homogeneous and inhomogeneous media. The method was also applied to a lung treatment, where significant differences in dose distributions, especially in the low-density region, were observed when compared with the results using an equivalent pathlength method. Comparison of the DVHs showed that the Monte Carlo calculated plan predicted an underdose of nearly 20% to the target, while the maximum doses to the cord and the heart were increased by 25% and 33%, respectively. These results suggested that the Monte Carlo method may have an impact on treatment designs, and also that it can be used as a benchmark to assess the accuracy of other dose calculation algorithms. The computation time for the lung case employing five 15-MV wedged beams, with an approximate field size of 13 X 13 cm and the dose grid size of 0.375 cm, was less than 14 h on a 175-MHz computer with a standard deviation of 1.5% in the high-dose region.

  5. Practical dose point-based methods to characterize dose distribution in a stationary elliptical body phantom for a cone-beam C-arm CT system

    PubMed Central

    Choi, Jang-Hwan; Constantin, Dragos; Ganguly, Arundhuti; Girard, Erin; Morin, Richard L.; Dixon, Robert L.; Fahrig, Rebecca

    2015-01-01

    Purpose: To propose new dose point measurement-based metrics to characterize the dose distributions and the mean dose from a single partial rotation of an automatic exposure control-enabled, C-arm-based, wide cone angle computed tomography system over a stationary, large, body-shaped phantom. Methods: A small 0.6 cm3 ion chamber (IC) was used to measure the radiation dose in an elliptical body-shaped phantom made of tissue-equivalent material. The IC was placed at 23 well-distributed holes in the central and peripheral regions of the phantom and dose was recorded for six acquisition protocols with different combinations of minimum kVp (109 and 125 kVp) and z-collimator aperture (full: 22.2 cm; medium: 14.0 cm; small: 8.4 cm). Monte Carlo (MC) simulations were carried out to generate complete 2D dose distributions in the central plane (z = 0). The MC model was validated at the 23 dose points against IC experimental data. The planar dose distributions were then estimated using subsets of the point dose measurements using two proposed methods: (1) the proximity-based weighting method (method 1) and (2) the dose point surface fitting method (method 2). Twenty-eight different dose point distributions with six different point number cases (4, 5, 6, 7, 14, and 23 dose points) were evaluated to determine the optimal number of dose points and their placement in the phantom. The performances of the methods were determined by comparing their results with those of the validated MC simulations. The performances of the methods in the presence of measurement uncertainties were evaluated. Results: The 5-, 6-, and 7-point cases had differences below 2%, ranging from 1.0% to 1.7% for both methods, which is a performance comparable to that of the methods with a relatively large number of points, i.e., the 14- and 23-point cases. However, with the 4-point case, the performances of the two methods decreased sharply. Among the 4-, 5-, 6-, and 7-point cases, the 7-point case (1.0% [±0

  6. A method to determine the planar dose distributions in patient undergone radiotherapy

    NASA Astrophysics Data System (ADS)

    Cilla, S.; Viola, P.; Augelli, B. G.; D'Onofrio, G.; Grimaldi, L.; Craus, M.; Digesù, C.; Deodato, F.; Macchia, G.; Morganti, A. G.; Fidanzio, A.; Azario, L.; Piermattei, A.

    2008-06-01

    A 2D-array equipped with 729 vented plane parallel ion-chambers has been calibrated as a portal dose detector for radiotherapy in vivo measurements. The array has been positioned by a radiographic film stand at 120 cm from the source orthogonal to the radiotherapy beam delivered with the gantry angle at 180°. The collision between the 2D-array and the patient's couch have been avoided. In this work, using the measurements of the portal detector, we present a method to reconstruct the dose variations in the patient treated with step and shoot intensity-modulated beams (IMRT) for head-neck tumours. For this treatment morphological changes often occur during the fractionated therapy. In a first step an in-house software supplied the comparison between the measured portal dose and the one computed by a commercial treatment planning system within the field of view of the computed tomography (CT) scanner. For each patient, the percentage Pγ of chambers, where the comparison is in agreement within a selected acceptance criteria, was determined 8 times. At the first radiotherapy fraction the γ-index analysis supplied Pγ values of about 95%, within acceptance criteria in terms of dose-difference, ΔD, and distance-agreement, Δd, that was equal to 5% and 4 mm, respectively. These acceptance criteria were taken into account for small errors in the patient's set-up reproducibility and for the accuracy of the portal dose calculated by the treatment planning system (TPS) in particular when the beam was attenuated by inhomogeneous tissues and the shape of the head-neck body contours were irregular. During the treatment, some patients showed a reduction of the Pγ below 90% because due to radiotherapy treatment there was a change of the patient's morphology. In a second step a method, based on dosimetric measurements that used standard phantoms, supplied the percentage dose variations in a coronal plane of the patient using the percentage dose variations measured by the 2D

  7. Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film.

    PubMed

    Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

    2016-01-01

    Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were -32.336 and -33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.

  8. A method to evaluate the dose increase in CT with iodinated contrast medium

    SciTech Connect

    Amato, Ernesto; Lizio, Domenico; Settineri, Nicola; Di Pasquale, Andrea; Salamone, Ignazio; Pandolfo, Ignazio

    2010-08-15

    Purpose: The objective of this study is to develop a method to calculate the relative dose increase when a computerized tomography scan (CT) is carried out after administration of iodinated contrast medium, with respect to the same CT scan in absence of contrast medium. Methods: A Monte Carlo simulation in GEANT4 of anthropomorphic neck and abdomen phantoms exposed to a simplified model of CT scanner was set up in order to calculate the increase of dose to thyroid, liver, spleen, kidneys, and pancreas as a function of the quantity of iodine accumulated; a series of experimental measurements of Hounsfield unit (HU) increment for known concentrations of iodinated contrast medium was carried out on a Siemens Sensation 16 CT scanner in order to obtain a relationship between the increment in HU and the relative dose increase in the organs studied. The authors applied such a method to calculate the average dose increase in three patients who underwent standard CT protocols consisting of one native scan in absence of contrast, followed by a contrast-enhanced scan in venous phase. Results: The authors validated their GEANT4 Monte Carlo simulation by comparing the resulting dose increases for iodine solutions in water with the ones presented in literature and with their experimental data obtained through a Roentgen therapy unit. The relative dose increases as a function of the iodine mass fraction accumulated and as a function of the Hounsfield unit increment between the contrast-enhanced scan and the native scan are presented. The data shown for the three patients exhibit an average relative dose increase between 22% for liver and 74% for kidneys; also, spleen (34%), pancreas (28%), and thyroid (48%) show a remarkable average increase. Conclusions: The method developed allows a simple evaluation of the dose increase when iodinated contrast medium is used in CT scans, basing on the increment in Hounsfield units observed on the patients' organs. Since many clinical protocols

  9. Evaluation of Deformable Image Registration Methods for Dose Monitoring in Head and Neck Radiotherapy

    PubMed Central

    Rigaud, Bastien; Simon, Antoine; Castelli, Joël; Gobeli, Maxime; Ospina Arango, Juan-David; Cazoulat, Guillaume; Henry, Olivier; Haigron, Pascal; De Crevoisier, Renaud

    2015-01-01

    In the context of head and neck cancer (HNC) adaptive radiation therapy (ART), the two purposes of the study were to compare the performance of multiple deformable image registration (DIR) methods and to quantify their impact for dose accumulation, in healthy structures. Fifteen HNC patients had a planning computed tomography (CT0) and weekly CTs during the 7 weeks of intensity-modulated radiation therapy (IMRT). Ten DIR approaches using different registration methods (demons or B-spline free form deformation (FFD)), preprocessing, and similarity metrics were tested. Two observers identified 14 landmarks (LM) on each CT-scan to compute LM registration error. The cumulated doses estimated by each method were compared. The two most effective DIR methods were the demons and the FFD, with both the mutual information (MI) metric and the filtered CTs. The corresponding LM registration accuracy (precision) was 2.44 mm (1.30 mm) and 2.54 mm (1.33 mm), respectively. The corresponding LM estimated cumulated dose accuracy (dose precision) was 0.85 Gy (0.93 Gy) and 0.88 Gy (0.95 Gy), respectively. The mean uncertainty (difference between maximal and minimal dose considering all the 10 methods) to estimate the cumulated mean dose to the parotid gland (PG) was 4.03 Gy (SD = 2.27 Gy, range: 1.06–8.91 Gy). PMID:25759821

  10. The combination of trastuzumab and pertuzumab administered at approved doses may delay development of trastuzumab resistance by additively enhancing antibody-dependent cell-mediated cytotoxicity.

    PubMed

    Tóth, Gábor; Szöőr, Árpád; Simon, László; Yarden, Yosef; Szöllősi, János; Vereb, György

    2016-10-01

    Although the recently concluded CLEOPATRA trial showed clinical benefits of combining trastuzumab and pertuzumab for treating HER2-positive metastatic breast cancer, trastuzumab monotherapy is still the mainstay in adjuvant settings. Since trastuzumab resistance occurs in over half of these cancers, we examined the mechanisms by which treatment of intrinsically trastuzumab-resistant and -sensitive tumors can benefit from the combination of these antibodies. F(ab')2 of both trastuzumab and pertuzumab were generated and validated in order to separately analyze antibody-dependent cell-mediated cytotoxicity (ADCC)-based and direct biological effects of the antibodies. Compared to monotherapy, combination of the two antibodies at clinically permitted doses enhanced the recruitment of natural killer cells responsible for ADCC, and significantly delayed the outgrowth of xenografts from intrinsically trastuzumab-resistant JIMT-1 cells. Antibody dose-response curves of in vitro ADCC showed that antibody-mediated killing can be saturated, and the two antibodies exert an additive effect at sub-saturation doses. Thus, the additive effect in vivo indicates that therapeutic tissue levels likely do not saturate ADCC. Additionally, isobole studies with the in vitro trastuzumab-sensitive BT-474 cells showed that the direct biological effect of combined treatment is additive, and surpasses the maximum effect of either monotherapy. Our results suggest the combined therapy is expected to give results that are superior to monotherapy, whatever the type of HER2-positive tumor may be. The combination of both antibodies at maximum clinically approved doses should thus be administered to patients to recruit maximum ADCC and cause maximum direct biological growth inhibition.

  11. The combination of trastuzumab and pertuzumab administered at approved doses may delay development of trastuzumab resistance by additively enhancing antibody-dependent cell-mediated cytotoxicity

    PubMed Central

    Tóth, Gábor; Szöőr, Árpád; Simon, László; Yarden, Yosef; Szöllősi, János; Vereb, György

    2016-01-01

    ABSTRACT Although the recently concluded CLEOPATRA trial showed clinical benefits of combining trastuzumab and pertuzumab for treating HER2-positive metastatic breast cancer, trastuzumab monotherapy is still the mainstay in adjuvant settings. Since trastuzumab resistance occurs in over half of these cancers, we examined the mechanisms by which treatment of intrinsically trastuzumab-resistant and -sensitive tumors can benefit from the combination of these antibodies. F(ab′)2 of both trastuzumab and pertuzumab were generated and validated in order to separately analyze antibody-dependent cell-mediated cytotoxicity (ADCC)-based and direct biological effects of the antibodies. Compared to monotherapy, combination of the two antibodies at clinically permitted doses enhanced the recruitment of natural killer cells responsible for ADCC, and significantly delayed the outgrowth of xenografts from intrinsically trastuzumab-resistant JIMT-1 cells. Antibody dose-response curves of in vitro ADCC showed that antibody-mediated killing can be saturated, and the two antibodies exert an additive effect at sub-saturation doses. Thus, the additive effect in vivo indicates that therapeutic tissue levels likely do not saturate ADCC. Additionally, isobole studies with the in vitro trastuzumab-sensitive BT-474 cells showed that the direct biological effect of combined treatment is additive, and surpasses the maximum effect of either monotherapy. Our results suggest the combined therapy is expected to give results that are superior to monotherapy, whatever the type of HER2-positive tumor may be. The combination of both antibodies at maximum clinically approved doses should thus be administered to patients to recruit maximum ADCC and cause maximum direct biological growth inhibition. PMID:27380003

  12. Additive antiemetic efficacy of low-doses of the cannabinoid CB(1/2) receptor agonist Δ(9)-THC with ultralow-doses of the vanilloid TRPV1 receptor agonist resiniferatoxin in the least shrew (Cryptotis parva).

    PubMed

    Darmani, Nissar A; Chebolu, Seetha; Zhong, Weixia; Trinh, Chung; McClanahan, Bryan; Brar, Rajivinder S

    2014-01-05

    Previous studies have shown that cannabinoid CB1/2 and vanilloid TRPV1 agonists (delta-9-tetrahydrocannabinol (Δ(9)-THC) and resiniferatoxin (RTX), respectively) can attenuate the emetic effects of chemotherapeutic agents such as cisplatin. In this study we used the least shrew to demonstrate whether combinations of varying doses of Δ(9)-THC with resiniferatoxin can produce additive antiemetic efficacy against cisplatin-induced vomiting. RTX by itself caused vomiting in a bell-shaped dose-dependent manner with maximal vomiting at 18 μg/kg when administered subcutaneously (s.c.) but not intraperitoneally (i.p.). Δ(9)-THC up to 10 mg/kg provides only 80% protection of least shrews from cisplatin-induced emesis with an ID50 of 0.3-1.8 mg/kg. Combinations of 1 or 5 μg/kg RTX with varying doses of Δ(9)-THC completely suppressed both the frequency and the percentage of shrews vomiting with ID50 dose values 5-50 times lower than Δ(9)-THC doses tested alone against cisplatin. A less potent TRPV1 agonist, capsaicin, by itself did not cause emesis (i.p. or s.c.), but it did significantly reduce vomiting induced by cisplatin given after 30 min but not at 2 h. The TRPV1-receptor antagonist, ruthenium red, attenuated cisplatin-induced emesis at 5mg/kg; however, another TRPV1-receptor antagonist, capsazepine, did not. In summary, we present evidence that combination of CB1/2 and TRPV1 agonists have the capacity to completely abolish cisplatin-induced emesis at doses that are ineffective when used individually.

  13. 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.

  14. Two non-parametric methods for derivation of constraints from radiotherapy dose-histogram data

    NASA Astrophysics Data System (ADS)

    Ebert, M. A.; Gulliford, S. L.; Buettner, F.; Foo, K.; Haworth, A.; Kennedy, A.; Joseph, D. J.; Denham, J. W.

    2014-07-01

    Dose constraints based on histograms provide a convenient and widely-used method for informing and guiding radiotherapy treatment planning. Methods of derivation of such constraints are often poorly described. Two non-parametric methods for derivation of constraints are described and investigated in the context of determination of dose-specific cut-points—values of the free parameter (e.g., percentage volume of the irradiated organ) which best reflect resulting changes in complication incidence. A method based on receiver operating characteristic (ROC) analysis and one based on a maximally-selected standardized rank sum are described and compared using rectal toxicity data from a prostate radiotherapy trial. Multiple test corrections are applied using a free step-down resampling algorithm, which accounts for the large number of tests undertaken to search for optimal cut-points and the inherent correlation between dose-histogram points. Both methods provide consistent significant cut-point values, with the rank sum method displaying some sensitivity to the underlying data. The ROC method is simple to implement and can utilize a complication atlas, though an advantage of the rank sum method is the ability to incorporate all complication grades without the need for grade dichotomization.

  15. Failed heart rate control with oral metoprolol prior to coronary CT angiography: effect of additional intravenous metoprolol on heart rate, image quality and radiation dose.

    PubMed

    Jiménez-Juan, Laura; Nguyen, Elsie T; Wintersperger, Bernd J; Moshonov, Hadas; Crean, Andrew M; Deva, Djeven P; Paul, Narinder S; Torres, Felipe S

    2013-01-01

    The purpose of this study was to evaluate the effect of intravenous (i.v.) metoprolol after a suboptimal heart rate (HR) response to oral metoprolol (75-150 mg) on HR control, image quality (IQ) and radiation dose during coronary CTA using 320-MDCT. Fifty-three consecutive patients who failed to achieve a target HR of < 60 bpm after an oral dose of metoprolol and required supplementary i.v. metoprolol (5-20 mg) prior to coronary CTA were evaluated. Patients with HR < 60 bpm during image acquisition were defined as responders (R) and those with HR ≥ 60 bpm as non-responders (NR). Two observers assessed IQ using a 3-point scale (1-2, diagnostic and 3, non-diagnostic). Effective dose (ED) was estimated using dose-length product and a 0.014 mSV/mGy.cm conversion factor. Baseline characteristics and HR on arrival were similar in the two groups. 58% of patients didn't achieve the target HR after receiving i.v. metoprolol (NR). R had a significantly higher HR reduction after oral (mean HR 63.9 ± 4.5 bpm vs. 69.6 ± 5.6 bpm) (p < 0.005) and i.v. (mean HR 55.4 ± 3.9 bpm vs. 67.4 ± 5.3 bpm) (p < 0.005) doses of metoprolol. Studies from NR showed a significantly higher ED in comparison to R (8.0 ± 2.9 vs. 6.1 ± 2.2 mSv) (p = 0.016) and a significantly higher proportion of non-diagnostic coronary segments (9.2 vs. 2.5%) (p < 0.001). 58% of patients who do not achieve a HR of <60 bpm prior to coronary CTA with oral fail to respond to additional i.v. metoprolol and have studies with higher radiation dose and worse image quality.

  16. Optimization of Couch Modeling in the Change of Dose Calculation Methods and Their Versions.

    PubMed

    Kuwahara, Junichi; Nakata, Manabu; Fujimoto, Takahiro; Nakamura, Mitsuhiro; Sasaki, Makoto; Tsuruta, Yusuke; Yano, Shinsuke; Higashimura, Kyoji; Hiraoka, Masahiro

    2017-01-01

    In external radiotherapy, the X-ray beam passes through the treatment couch, leading to the dose reduction by the attenuation of the couch. As a method to compensate for the reduction, radiation treatment planning systems (RTPS) support virtual couch function, namely "couch modeling method". In the couch modeling method, the computed tomography (CT) numbers assigned to each structure should be optimized by comparing calculations to measurements for accurate dose calculation. Thus, re-optimization of CT numbers will be required when the dose calculation algorithm or their version changes. The purpose of this study is to evaluate the calculation accuracy of the couch modeling method in different calculation algorithms and their versions. The optimal CT numbers were determined by minimizing the difference between measured transmission factors and calculated ones. When CT numbers optimized by Anisotropic Analytical Algorithm (AAA) Ver. 8.6 were used, the maximum and the mean difference of transmission factor were 5.8% and 1.5%, respectively, for Acuros XB (AXB) Ver. 11.0. However, when CT numbers optimized by AXB Ver. 11.0 were used, they were 2.6% and 0.6%, respectively. The CT numbers for couch structures should be optimized when changing dose calculation algorithms and their versions. From the comparison of the measured transmission to calculation, it was found that the CT numbers had high accuracy.

  17. Respiratory triggered 4D cone-beam computed tomography: A novel method to reduce imaging dose

    SciTech Connect

    Cooper, Benjamin J.; O'Brien, Ricky T.; Keall, Paul J.; Balik, Salim; Hugo, Geoffrey D.

    2013-04-15

    Purpose: A novel method called respiratory triggered 4D cone-beam computed tomography (RT 4D CBCT) is described whereby imaging dose can be reduced without degrading image quality. RT 4D CBCT utilizes a respiratory signal to trigger projections such that only a single projection is assigned to a given respiratory bin for each breathing cycle. In contrast, commercial 4D CBCT does not actively use the respiratory signal to minimize image dose. Methods: To compare RT 4D CBCT with conventional 4D CBCT, 3600 CBCT projections of a thorax phantom were gathered and reconstructed to generate a ground truth CBCT dataset. Simulation pairs of conventional 4D CBCT acquisitions and RT 4D CBCT acquisitions were developed assuming a sinusoidal respiratory signal which governs the selection of projections from the pool of 3600 original projections. The RT 4D CBCT acquisition triggers a single projection when the respiratory signal enters a desired acquisition bin; the conventional acquisition does not use a respiratory trigger and projections are acquired at a constant frequency. Acquisition parameters studied were breathing period, acquisition time, and imager frequency. The performance of RT 4D CBCT using phase based and displacement based sorting was also studied. Image quality was quantified by calculating difference images of the test dataset from the ground truth dataset. Imaging dose was calculated by counting projections. Results: Using phase based sorting RT 4D CBCT results in 47% less imaging dose on average compared to conventional 4D CBCT. Image quality differences were less than 4% at worst. Using displacement based sorting RT 4D CBCT results in 57% less imaging dose on average, than conventional 4D CBCT methods; however, image quality was 26% worse with RT 4D CBCT. Conclusions: Simulation studies have shown that RT 4D CBCT reduces imaging dose while maintaining comparable image quality for phase based 4D CBCT; image quality is degraded for displacement based RT 4D

  18. Effect of various methods for rectum delineation on relative and absolute dose-volume histograms for prostate IMRT treatment planning

    SciTech Connect

    Kusumoto, Chiaki; Ohira, Shingo; Miyazaki, Masayoshi; Ueda, Yoshihiro; Isono, Masaru; Teshima, Teruki

    2016-07-01

    regardless of differences in rectal length at all dose levels. Moreover, at high dose levels (V{sub 70}), the parameters of A-DVHs showed less dependence on rectal cross sections (Sh-Rec vs Sh-Rw: R = 0.66; Lg-Rec vs Lg-Rw: R = 0.59). This study showed that A-DVHs were less dependent on the delineation methods than R-DVHs, especially for evaluating the rectal dose at higher dose levels. It can therefore be assumed that, in addition to R-DVHs, A-DVHs can be used for evaluating rectal toxicity.

  19. TH-A-19A-03: Impact of Proton Dose Calculation Method On Delivered Dose to Lung Tumors: Experiments in Thorax Phantom and Planning Study in Patient Cohort

    SciTech Connect

    Grassberger, C; Daartz, J; Dowdell, S; Ruggieri, T; Sharp, G; Paganetti, H

    2014-06-15

    Purpose: Evaluate Monte Carlo (MC) dose calculation and the prediction of the treatment planning system (TPS) in a lung phantom and compare them in a cohort of 20 lung patients treated with protons. Methods: A 2-dimensional array of ionization chambers was used to evaluate the dose across the target in a lung phantom. 20 lung cancer patients on clinical trials were re-simulated using a validated Monte Carlo toolkit (TOPAS) and compared to the TPS. Results: MC increases dose calculation accuracy in lung compared to the clinical TPS significantly and predicts the dose to the target in the phantom within ±2%: the average difference between measured and predicted dose in a plane through the center of the target is 5.6% for the TPS and 1.6% for MC. MC recalculations in patients show a mean dose to the clinical target volume on average 3.4% lower than the TPS, exceeding 5% for small fields. The lower dose correlates significantly with aperture size and the distance of the tumor to the chest wall (Spearman's p=0.0002/0.004). For large tumors MC also predicts consistently higher V{sub 5} and V{sub 10} to the normal lung, due to a wider lateral penumbra, which was also observed experimentally. Critical structures located distal to the target can show large deviations, though this effect is very patient-specific. Conclusion: Advanced dose calculation techniques, such as MC, would improve treatment quality in proton therapy for lung cancer by avoiding systematic overestimation of target dose and underestimation of dose to normal lung. This would increase the accuracy of the relationships between dose and effect, concerning tumor control as well as normal tissue toxicity. As the role of proton therapy in the treatment of lung cancer continues to be evaluated in clinical trials, this is of ever-increasing importance. This work was supported by National Cancer Institute Grant R01CA111590.

  20. A method for depth-dose distribution measurements in tissue irradiated by a proton beam

    SciTech Connect

    Gambarini, G.; Birattari, C.; Bartolo, D. de

    1994-12-31

    The use of protons and heavy ions for the treatment of malignant and non-malignant disease has aroused a growing interest in the last decade. The notable advantage of heavy charged particles over photons in external beam radiotherapy lies in the possibility of irradiating a small localized region within the body, keeping a low value for the entrance dose. Owing to this high disuniformity of energy deposition, an essential requirement for treatment planning is a precise evaluation of the spatial distribution of absorbed dose. The proposed method for depth-dose distribution measurements utilizes a chemical dosimeter (ferrous sulphate solution plus sulfuric acid and eventually xylenol orange) incorporated in a gelatine, whose role is the maintenance of spatial information. Ionizing radiation causes a variation in some parameters of the system such as the proton relaxation rates in the solution (measurable by NMR analysis) or the optical absorption of the gel in the visible spectrum (measurable by spectrophotometry).

  1. An adaptive two-stage dose-response design method for establishing Proof of Concept

    PubMed Central

    Franchetti, Yoko; Anderson, Stewart J.; Sampson, Allan R.

    2013-01-01

    We propose an adaptive two-stage dose-response design where a pre-specified adaptation rule is used to add and/or drop treatment arms between the stages. We extend the multiple comparison procedures-modeling (MCP-Mod) approach into a two-stage design. In each stage, we use the same set of candidate dose-response models and test for a dose-response relationship or proof of concept (PoC) via model-associated statistics. The stage-wise test results are then combined to establish ‘global’ PoC using a conditional error function. Our simulation studies showed good and more robust power in our design method compared to conventional and fixed designs. PMID:23957520

  2. Absorbed Dose Calculations Using Mesh-based Human Phantoms And Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Kramer, Richard

    2011-08-01

    Health risks attributable to the exposure to ionizing radiation are considered to be a function of the absorbed or equivalent dose to radiosensitive organs and tissues. However, as human tissue cannot express itself in terms of equivalent dose, exposure models have to be used to determine the distribution of equivalent dose throughout the human body. An exposure model, be it physical or computational, consists of a representation of the human body, called phantom, plus a method for transporting ionizing radiation through the phantom and measuring or calculating the equivalent dose to organ and tissues of interest. The FASH2 (Female Adult meSH) and the MASH2 (Male Adult meSH) computational phantoms have been developed at the University of Pernambuco in Recife/Brazil based on polygon mesh surfaces using open source software tools and anatomical atlases. Representing standing adults, FASH2 and MASH2 have organ and tissue masses, body height and body mass adjusted to the anatomical data published by the International Commission on Radiological Protection for the reference male and female adult. For the purposes of absorbed dose calculations the phantoms have been coupled to the EGSnrc Monte Carlo code, which can transport photons, electrons and positrons through arbitrary media. This paper reviews the development of the FASH2 and the MASH2 phantoms and presents dosimetric applications for X-ray diagnosis and for prostate brachytherapy.

  3. Film dosimetry calibration method for pulsed-dose-rate brachytherapy with an 192Ir source.

    PubMed

    Schwob, Nathan; Orion, Itzhak

    2007-05-01

    192Ir sources have been widely used in clinical brachytherapy. An important challenge is to perform dosimetric measurements close to the source despite the steep dose gradient. The common, inexpensive silver halide film is a classic two-dimensional integrator dosimeter and would be an attractive solution for these dose measurements. The main disadvantage of film dosimetry is the film response to the low-energy photon. Since the photon energy spectrum is known to vary with depth, the sensitometric curves are expected to be dependent on depth. The purpose of this study is to suggest a correction method for silver halide film dosimetry that overcomes the response changes at different depths. Sensitometric curves have been obtained at different depths with verification film near a 1 Ci 192Ir pulsed-dose-rate source. The depth dependence of the film response was observed and a correction function was established. The suitability of the method was tested through measurement of the radial dose profile and radial dose function. The results were compared to Monte Carlo-simulated values according to the TG43 formalism. Monte Carlo simulations were performed separately for the beta and gamma source emissions, using the EGS4 code system, including the low-energy photon and electron transport optimization procedures. The beta source emission simulation showed that the beta dose contribution could be neglected and therefore the film-depth dependence could not be attributed to this part of the source radioactivity. The gamma source emission simulations included photon-spectra collection at several depths. The results showed a depth-dependent softening of the photon spectrum that can explain the film-energy dependence.

  4. SU-E-T-91: Correction Method to Determine Surface Dose for OSL Detectors

    SciTech Connect

    Reynolds, T; Higgins, P

    2014-06-01

    Purpose: OSL detectors are commonly used in clinic due to their numerous advantages, such as linear response, negligible energy, angle and temperature dependence in clinical range, for verification of the doses beyond the dmax. Although, due to the bulky shielding envelope, this type of detectors fails to measure skin dose, which is an important assessment of patient ability to finish the treatment on time and possibility of acute side effects. This study aims to optimize the methodology of determination of skin dose for conventional accelerators and a flattening filter free Tomotherapy. Methods: Measurements were done for x-ray beams: 6 MV (Varian Clinac 2300, 10×10 cm{sup 2} open field, SSD = 100 cm) and for 5.5 MV (Tomotherapy, 15×40 cm{sup 2} field, SAD = 85 cm). The detectors were placed at the surface of the solid water phantom and at the reference depth (dref=1.7cm (Varian 2300), dref =1.0 cm (Tomotherapy)). The measurements for OSLs were related to the externally exposed OSLs measurements, and further were corrected to surface dose using an extrapolation method indexed to the baseline Attix ion chamber measurements. A consistent use of the extrapolation method involved: 1) irradiation of three OSLs stacked on top of each other on the surface of the phantom; 2) measurement of the relative dose value for each layer; and, 3) extrapolation of these values to zero thickness. Results: OSL measurements showed an overestimation of surface doses by the factor 2.31 for Varian 2300 and 2.65 for Tomotherapy. The relationships: SD{sup 2300} = 0.68 × M{sup 2300}-12.7 and SDτoμo = 0.73 × Mτoμo-13.1 were found to correct the single OSL measurements to surface doses in agreement with Attix measurements to within 0.1% for both machines. Conclusion: This work provides simple empirical relationships for surface dose measurements using single OSL detectors.

  5. TU-EF-204-09: A Preliminary Method of Risk-Informed Optimization of Tube Current Modulation for Dose Reduction in CT

    SciTech Connect

    Gao, Y; Liu, B; Kalra, M; Caracappa, P; Liu, T; Li, X; Xu, X

    2015-06-15

    Purpose: X-rays from CT scans can increase cancer risk to patients. Lifetime Attributable Risk of Cancer Incidence for adult patients has been investigated and shown to decrease as patient age. However, a new risk model shows an increasing risk trend for several radiosensitive organs for middle age patients. This study investigates the feasibility of a general method for optimizing tube current modulation (TCM) functions to minimize risk by reducing radiation dose to radiosensitive organs of patients. Methods: Organ-based TCM has been investigated in literature for eye lens dose and breast dose. Adopting the concept in organ-based TCM, this study seeks to find an optimized tube current for minimal total risk to breasts and lungs by reducing dose to these organs. The contributions of each CT view to organ dose are determined through simulations of CT scan view-by-view using a GPU-based fast Monte Carlo code, ARCHER. A Linear Programming problem is established for tube current optimization, with Monte Carlo results as weighting factors at each view. A pre-determined dose is used as upper dose boundary, and tube current of each view is optimized to minimize the total risk. Results: An optimized tube current is found to minimize the total risk of lungs and breasts: compared to fixed current, the risk is reduced by 13%, with breast dose reduced by 38% and lung dose reduced by 7%. The average tube current is maintained during optimization to maintain image quality. In addition, dose to other organs in chest region is slightly affected, with relative change in dose smaller than 10%. Conclusion: Optimized tube current plans can be generated to minimize cancer risk to lungs and breasts while maintaining image quality. In the future, various risk models and greater number of projections per rotation will be simulated on phantoms of different gender and age. National Institutes of Health R01EB015478.

  6. Statistical analysis of dose heterogeneity in circulating blood: Implications for sequential methods of total body irradiation

    SciTech Connect

    Molloy, Janelle A.

    2010-11-15

    Purpose: Improvements in delivery techniques for total body irradiation (TBI) using Tomotherapy and intensity modulated radiation therapy have been proven feasible. Despite the promise of improved dose conformality, the application of these ''sequential'' techniques has been hampered by concerns over dose heterogeneity to circulating blood. The present study was conducted to provide quantitative evidence regarding the potential clinical impact of this heterogeneity. Methods: Blood perfusion was modeled analytically as possessing linear, sinusoidal motion in the craniocaudal dimension. The average perfusion period for human circulation was estimated to be approximately 78 s. Sequential treatment delivery was modeled as a Gaussian-shaped dose cloud with a 10 cm length that traversed a 183 cm patient length at a uniform speed. Total dose to circulating blood voxels was calculated via numerical integration and normalized to 2 Gy per fraction. Dose statistics and equivalent uniform dose (EUD) were calculated for relevant treatment times, radiobiological parameters, blood perfusion rates, and fractionation schemes. The model was then refined to account for random dispersion superimposed onto the underlying periodic blood flow. Finally, a fully stochastic model was developed using binomial and trinomial probability distributions. These models allowed for the analysis of nonlinear sequential treatment modalities and treatment designs that incorporate deliberate organ sparing. Results: The dose received by individual blood voxels exhibited asymmetric behavior that depended on the coherence among the blood velocity, circulation phase, and the spatiotemporal characteristics of the irradiation beam. Heterogeneity increased with the perfusion period and decreased with the treatment time. Notwithstanding, heterogeneity was less than {+-}10% for perfusion periods less than 150 s. The EUD was compromised for radiosensitive cells, long perfusion periods, and short treatment times

  7. Increased pattern transfer fidelity ZEP 520A during reactive ion etching through chemical modifications by additional dosing of the electron beam resist.

    SciTech Connect

    Czaplewski, D. A.; Ocola, L. E.

    2011-03-01

    This article describes a postdevelopment, additional electron exposure to enhance the etch selectivity and improve pattern transfer fidelity of an electron beam resist, ZEP 520A, through chemical changes of the resist. After the critical features were patterned and developed, the resist was exposed at 5 kV accelerating voltage to a second dose of electrons ranging from 300 to 300,000 {micro}C/cm{sup 2}. The etch rate of the resist decreased by approximately 25% in a CHF{sub 3} and O{sub 2} plasma. More critically, the fidelity of the pattern transfer was improved. Infrared and Raman spectroscopies were used to characterize the resist before and after electron beam exposure for doses up to 3000 {micro}C/cm{sup 2}. The carbonyl bonding in the polymer showed significant changes after electron beam exposure that can be associated with improvement in the etch performance of this resist.

  8. A method for calculating Bayesian uncertainties on internal doses resulting from complex occupational exposures.

    PubMed

    Puncher, M; Birchall, A; Bull, R K

    2012-08-01

    Estimating uncertainties on doses from bioassay data is of interest in epidemiology studies that estimate cancer risk from occupational exposures to radionuclides. Bayesian methods provide a logical framework to calculate these uncertainties. However, occupational exposures often consist of many intakes, and this can make the Bayesian calculation computationally intractable. This paper describes a novel strategy for increasing the computational speed of the calculation by simplifying the intake pattern to a single composite intake, termed as complex intake regime (CIR). In order to assess whether this approximation is accurate and fast enough for practical purposes, the method is implemented by the Weighted Likelihood Monte Carlo Sampling (WeLMoS) method and evaluated by comparing its performance with a Markov Chain Monte Carlo (MCMC) method. The MCMC method gives the full solution (all intakes are independent), but is very computationally intensive to apply routinely. Posterior distributions of model parameter values, intakes and doses are calculated for a representative sample of plutonium workers from the United Kingdom Atomic Energy cohort using the WeLMoS method with the CIR and the MCMC method. The distributions are in good agreement: posterior means and Q(0.025) and Q(0.975) quantiles are typically within 20 %. Furthermore, the WeLMoS method using the CIR converges quickly: a typical case history takes around 10-20 min on a fast workstation, whereas the MCMC method took around 12-72 hr. The advantages and disadvantages of the method are discussed.

  9. A practical method for skin dose estimation in interventional cardiology based on fluorographic DICOM information.

    PubMed

    Matthews, Lucy; Dixon, Matthew; Rowles, Nick; Stevens, Greg

    2016-03-01

    A practical method for skin dose estimation for interventional cardiology patients has been developed to inform pre-procedure planning and post-procedure patient management. Absorbed dose to the patient skin for certain interventional radiology procedures can exceed thresholds for deterministic skin injury, requiring documentation within the patient notes and appropriate patient follow-up. The primary objective was to reduce uncertainty associated with current methods, particularly surrounding field overlap. This was achieved by considering rectangular field geometry incident on a spherical patient model in a polar coordinate system. The angular size of each field was quantified at surface of the sphere, i.e. the skin surface. Computer-assisted design software enabled the modelling of a sufficient dataset that was subsequently validated with radiochromic film. Modelled overlap was found to agree with overlap measured using film to within 2.2° ± 2.0°, showing that the overall error associated with the model was < 1 %. Mathematical comparison against exposure data extracted from procedural Digital Imaging and Communication in Medicine files was used to generate a graphical skin dose map, demonstrating the dose distribution over a sphere centred at the interventional reference point. Dosimetric accuracy of the software was measured as between 3.5 and 17 % for different variables.

  10. A simple method of independent treatment time verification in gamma knife radiosurgery using integral dose

    SciTech Connect

    Jin Jianyue; Drzymala, Robert; Li Zuofeng

    2004-12-01

    The purpose of this study is to develop a simple independent dose calculation method to verify treatment plans for Leksell Gamma Knife radiosurgery. Our approach uses the total integral dose within the skull as an end point for comparison. The total integral dose is computed using a spreadsheet and is compared to that obtained from Leksell GammaPlan registered . It is calculated as the sum of the integral doses of 201 beams, each passing through a cylindrical volume. The average length of the cylinders is estimated from the Skull-Scaler measurement data taken before treatment. Correction factors are applied to the length of the cylinder depending on the location of a shot in the skull. The radius of the cylinder corresponds to the collimator aperture of the helmet, with a correction factor for the beam penumbra and scattering. We have tested our simple spreadsheet program using treatment plans of 40 patients treated with Gamma Knife registered in our center. These patients differ in geometry, size, lesion locations, collimator helmet, and treatment complexities. Results show that differences between our calculations and treatment planning results are typically within {+-}3%, with a maximum difference of {+-}3.8%. We demonstrate that our spreadsheet program is a convenient and effective independent method to verify treatment planning irradiation times prior to implementation of Gamma Knife radiosurgery.

  11. NDE of additively manufactured components with embedded defects (reference standards) using conventional and advanced ultrasonic methods

    NASA Astrophysics Data System (ADS)

    Koester, L.; Roberts, R. A.; Barnard, D. J.; Chakrapani, S.; Singh, S.; Hogan, R.; Bond, L. J.

    2017-02-01

    Additive manufacturing provides a unique opportunity to embed defects of known size and shape to produce reference samples for inspection and quality control purposes. This paper reports defect detectability studies with cylindrical additively manufactured cobalt-chromium alloy specimens which contain defects of known sizes and distributions. The specimens were characterized using immersion, synthetic aperture focusing (SAFT), phased array, and nonlinear ultrasonic techniques. Results include detectability, signal to noise ratios, and comparison of results between the methods and what is believed to be the first determination of a non-linearity (beta) parameter for an additively manufactured material. The results indicate that additive manufacturing provides a valuable method to produce reference samples, though additional work is required to validate the shape and morphology of the defects specified.

  12. A simple method to retrospectively estimate patient dose-area product for chest tomosynthesis examinations performed using VolumeRAD

    SciTech Connect

    Båth, Magnus Svalkvist, Angelica; Söderman, Christina

    2014-10-15

    Purpose: The purpose of the present work was to develop and validate a method of retrospectively estimating the dose-area product (DAP) of a chest tomosynthesis examination performed using the VolumeRAD system (GE Healthcare, Chalfont St. Giles, UK) from digital imaging and communications in medicine (DICOM) data available in the scout image. Methods: DICOM data were retrieved for 20 patients undergoing chest tomosynthesis using VolumeRAD. Using information about how the exposure parameters for the tomosynthesis examination are determined by the scout image, a correction factor for the adjustment in field size with projection angle was determined. The correction factor was used to estimate the DAP for 20 additional chest tomosynthesis examinations from DICOM data available in the scout images, which was compared with the actual DAP registered for the projection radiographs acquired during the tomosynthesis examination. Results: A field size correction factor of 0.935 was determined. Applying the developed method using this factor, the average difference between the estimated DAP and the actual DAP was 0.2%, with a standard deviation of 0.8%. However, the difference was not normally distributed and the maximum error was only 1.0%. The validity and reliability of the presented method were thus very high. Conclusions: A method to estimate the DAP of a chest tomosynthesis examination performed using the VolumeRAD system from DICOM data in the scout image was developed and validated. As the scout image normally is the only image connected to the tomosynthesis examination stored in the picture archiving and communication system (PACS) containing dose data, the method may be of value for retrospectively estimating patient dose in clinical use of chest tomosynthesis.

  13. 76 FR 65382 - Regulation of Fuel and Fuel Additives: Alternative Test Method for Olefins in Gasoline

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-21

    ... AGENCY 40 CFR Part 80 RIN 2060-AP17 Regulation of Fuel and Fuel Additives: Alternative Test Method for... alternative test method for olefin content in gasoline. This final rule will provide flexibility to the... environmental benefits achieved from our fuels programs. ] DATES: This rule is effective November 21,...

  14. Review of methods of dose estimation for epidemiological studies of the radiological impact of nevada test site and global fallout.

    PubMed

    Beck, Harold L; Anspaugh, Lynn R; Bouville, André; Simon, Steven L

    2006-07-01

    Methods to assess radiation doses from nuclear weapons test fallout have been used to estimate doses to populations and individuals in a number of studies. However, only a few epidemiology studies have relied on fallout dose estimates. Though the methods for assessing doses from local and regional compared to global fallout are similar, there are significant differences in predicted doses and contributing radionuclides depending on the source of the fallout, e.g. whether the nuclear debris originated in Nevada at the U.S. nuclear test site or whether it originated at other locations worldwide. The sparse historical measurement data available are generally sufficient to estimate external exposure doses reasonably well. However, reconstruction of doses to body organs from ingestion and inhalation of radionuclides is significantly more complex and is almost always more uncertain than are external dose estimates. Internal dose estimates are generally based on estimates of the ground deposition per unit area of specific radionuclides and subsequent transport of radionuclides through the food chain. A number of technical challenges to correctly modeling deposition of fallout under wet and dry atmospheric conditions still remain, particularly at close-in locations where sizes of deposited particles vary significantly over modest changes in distance. This paper summarizes the various methods of dose estimation from weapons test fallout and the most important dose assessment and epidemiology studies that have relied on those methods.

  15. RADRUE METHOD FOR RECONSTRUCTION OF EXTERNAL PHOTON DOSES TO CHERNOBYL LIQUIDATORS IN EPIDEMIOLOGICAL STUDIES

    PubMed Central

    Kryuchkov, Victor; Chumak, Vadim; Maceika, Evaldas; Anspaugh, Lynn R.; Cardis, Elisabeth; Bakhanova, Elena; Golovanov, Ivan; Drozdovitch, Vladimir; Luckyanov, Nickolas; Kesminiene, Ausrele; Voillequé, Paul; Bouville, André

    2010-01-01

    Between 1986 and 1990, several hundred thousand workers, called “liquidators” or “clean-up workers”, took part in decontamination and recovery activities within the 30-km zone around the Chernobyl nuclear power plant in Ukraine, where a major accident occurred in April 1986. The Chernobyl liquidators were mainly exposed to external ionizing radiation levels that depended primarily on their work locations and the time after the accident when the work was performed. Because individual doses were often monitored inadequately or were not monitored at all for the majority of liquidators, a new method of photon (i.e. gamma and x-rays) dose assessment, called “RADRUE” (Realistic Analytical Dose Reconstruction with Uncertainty Estimation) was developed to obtain unbiased and reasonably accurate estimates for use in three epidemiologic studies of hematological malignancies and thyroid cancer among liquidators. The RADRUE program implements a time-and-motion dose reconstruction method that is flexible and conceptually easy to understand. It includes a large exposure rate database and interpolation and extrapolation techniques to calculate exposure rates at places where liquidators lived and worked within ~70 km of the destroyed reactor. The RADRUE technique relies on data collected from subjects’ interviews conducted by trained interviewers, and on expert dosimetrists to interpret the information and provide supplementary information, when necessary, based upon their own Chernobyl experience. The RADRUE technique was used to estimate doses from external irradiation, as well as uncertainties, to the bone-marrow for 929 subjects and to the thyroid gland for 530 subjects enrolled in epidemiologic studies. Individual bone-marrow dose estimates were found to range from less than one μGy to 3,300 mGy, with an arithmetic mean of 71 mGy. Individual thyroid dose estimates were lower and ranged from 20 μGy to 507 mGy, with an arithmetic mean of 29 mGy. The

  16. 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.

  17. The addition of high-dose tamoxifen to standard radiotherapy does not improve the survival of patients with diffuse intrinsic pontine glioma.

    PubMed

    Michalski, Antony; Bouffet, Eric; Taylor, Roger E; Hargrave, Darren; Walker, David; Picton, Susan; Robinson, Kathryn; Pizer, Barry; Bujkiewicz, Sylwia

    2010-10-01

    The study aimed to examine the tolerability of the combination of radiotherapy and tamoxifen and the effect on median and event free survival as well as collecting data on the use of steroids in this population. 31 patients with diffuse intrinsic pontine glioma, diagnosed on clinical and radiological criteria, were treated with high-dose oral tamoxifen (120 mg/m(2)/day) given concomitantly with standard dose radiotherapy (54 Gy in 1.8 Gy fractions over 6 weeks). Results Tamoxifen was well tolerated with no grade 3 or 4 CTC toxicity reported. At 1 year, the progression free and event free survival were 3.2% (95% CI: 0.2-14.1%), and at 6 months 19.4% (CI: 7.9% to 34.6%). The overall survival at 1 year was 16.1% (CI: 5.9-30.9%) with median survival 6.32 months. In this study, in which tamoxifen was used in conjunction with radiotherapy, progression free survival was shown to be less good when compared with historical data HR = 3.1 (CI: 1.7-5.7). There was no significant reduction in overall survival. The addition of high-dose tamoxifen, although well tolerated, confers no clinical benefit to patients treated with diffuse intrinsic pontine glioma treated with standard radiotherapy.

  18. A Study on the Efficacy of the Addition of Low Dose Dexmedetomidine as an Adjuvant to Lignocaine in Intravenous Regional Anaesthesia (IVRA)

    PubMed Central

    Menezes, Yvonne; D’souza, Shirley Ann

    2016-01-01

    Introduction Intravenous Regional Anaesthesia (IVRA) is a simple, effective method of providing anaesthesia for short duration surgical procedures on the extremities, its chief drawbacks are tourniquet pain, short duration of block and absence of post-operative analgesia. Dexmedetomidine is known to reduce anaesthetic requirements and also provide analgesia to the patient. Aim To evaluate the efficacy of dexmedetomidine as an adjuvant to lignocaine in IVRA with respect to the quality of the block, tourniquet pain and post-operative analgesia. Materials and Methods A prospective, randomized, double-blinded study was conducted on 60 patients scheduled for orthopaedic surgery of the upper limb, of American Society of Anaesthesiologist’s physical status grades I and II. They were divided into two groups of 30 each. The control group C received 40ml of 0.5% lignocaine with saline and Group D received dexmedetomidine 0.5μg/kg added to 40ml of 0.5% lignocaine. The time taken for the onset and recovery of sensory and motor block, incidence of tourniquet pain, intra-operative and post-operative Visual Analogue Scale (VAS) scores, duration of post-operative analgesia and any side effects were noted. Student t-test was used for evaluation of the demographic data, haemodynamic variables, the onset and recovery times of block, duration of analgesia and intra-operative analgesic consumption and tourniquet pain. Friedman’s test was used for intra-operative and post-operative VAS and sedation scores. Results The onset time of both sensory and motor block were significantly shortened, the recovery of sensory and motor block was prolonged, the incidence of tourniquet pain was comparatively lesser and there was significantly increased duration of post-operative analgesia in the dexmedetomidine group. Haemodynamic parameters were similar in both groups. Conclusion The addition of 0.5μg/kg of dexmedetomidine as an adjuvant to IVRA effectively enhances the anaesthesia and post

  19. A new approach to NMR chemical shift additivity parameters using simultaneous linear equation method.

    PubMed

    Shahab, Yosif A; Khalil, Rabah A

    2006-10-01

    A new approach to NMR chemical shift additivity parameters using simultaneous linear equation method has been introduced. Three general nitrogen-15 NMR chemical shift additivity parameters with physical significance for aliphatic amines in methanol and cyclohexane and their hydrochlorides in methanol have been derived. A characteristic feature of these additivity parameters is the individual equation can be applied to both open-chain and rigid systems. The factors that influence the (15)N chemical shift of these substances have been determined. A new method for evaluating conformational equilibria at nitrogen in these compounds using the derived additivity parameters has been developed. Conformational analyses of these substances have been worked out. In general, the results indicate that there are four factors affecting the (15)N chemical shift of aliphatic amines; paramagnetic term (p-character), lone pair-proton interactions, proton-proton interactions, symmetry of alkyl substituents and molecular association.

  20. A coupled deterministic/stochastic method for computing neutron capture therapy dose rates

    NASA Astrophysics Data System (ADS)

    Hubbard, Thomas Richard

    Neutron capture therapy (NCT) is an experimental method of treating brain tumors and other cancers by: (1) injecting or infusing the patient with a tumor-seeking, neutron target-labeled drug; and (2) irradiating the patient in an intense epithermal neutron fluence. The nuclear reaction between the neutrons and the target nuclei (e.g. sp{10}B(n,alpha)sp7Lirbrack releases energy in the form of high-LET (i.e. energy deposited within the range of a cell diameter) reaction particles which selectively kill the tumor cell. The efficacy of NCT is partly dependent on the delivery of maximum thermal neutron fluence to the tumor and the minimization of radiation dose to healthy tissue. Since the filtered neutron source (e.g. research reactor) usually provides a broad energy spectrum of highly-penetrating neutron and gamma-photon radiation, detailed transport calculations are necessary in order to plan treatments that use optimal treatment facility configurations and patient positioning. Current computational methods for NCT use either discrete ordinates calculation or, more often, Monte Carlo simulation to predict neutron fluences in the vicinity of the tumor. These methods do not, however, accurately calculate the transport of radiation throughout the entire facility or the deposition of dose in all the various parts of the body due to shortcomings of using either method alone. A computational method, specifically designed for NCT problems, has been adapted from the MASH methodology and couples a forward discrete ordinates (Ssb{n}) calculation with an adjoint Monte Carlo run to predict the dose at any point within the patient. The transport from the source through the filter/collimator is performed with a forward DORT run, and this is then coupled to adjoint MORSE results at a selected coupling parallelepiped which surrounds human phantom. Another routine was written to allow the user to generate the MORSE models at various angles and positions within the treatment room. The

  1. An in vivo dose verification method for SBRT–VMAT delivery using the EPID

    SciTech Connect

    McCowan, P. M.; Van Uytven, E.; Van Beek, T.; Asuni, G.; McCurdy, B. M. C.

    2015-12-15

    Purpose: Radiation treatments have become increasingly more complex with the development of volumetric modulated arc therapy (VMAT) and the use of stereotactic body radiation therapy (SBRT). SBRT involves the delivery of substantially larger doses over fewer fractions than conventional therapy. SBRT–VMAT treatments will strongly benefit from in vivo patient dose verification, as any errors in delivery can be more detrimental to the radiobiology of the patient as compared to conventional therapy. Electronic portal imaging devices (EPIDs) are available on most commercial linear accelerators (Linacs) and their documented use for dosimetry makes them valuable tools for patient dose verification. In this work, the authors customize and validate a physics-based model which utilizes on-treatment EPID images to reconstruct the 3D dose delivered to the patient during SBRT–VMAT delivery. Methods: The SBRT Linac head, including jaws, multileaf collimators, and flattening filter, were modeled using Monte Carlo methods and verified with measured data. The simulation provides energy spectrum data that are used by their “forward” model to then accurately predict fluence generated by a SBRT beam at a plane above the patient. This fluence is then transported through the patient and then the dose to the phosphor layer in the EPID is calculated. Their “inverse” model back-projects the EPID measured focal fluence to a plane upstream of the patient and recombines it with the extra-focal fluence predicted by the forward model. This estimate of total delivered fluence is then forward projected onto the patient’s density matrix and a collapsed cone convolution algorithm calculates the dose delivered to the patient. The model was tested by reconstructing the dose for two prostate, three lung, and two spine SBRT–VMAT treatment fractions delivered to an anthropomorphic phantom. It was further validated against actual patient data for a lung and spine SBRT–VMAT plan. The

  2. Methods for meta-analysis of pharmacodynamic dose-response data with application to multi-arm studies of alogliptin.

    PubMed

    Langford, Oliver; Aronson, Jeffrey K; van Valkenhoef, Gert; Stevens, Richard J

    2016-03-17

    Standard methods for meta-analysis of dose-response data in epidemiology assume a model with a single scalar parameter, such as log-linear relationships between exposure and outcome; such models are implicitly unbounded. In contrast, in pharmacology, multi-parameter models, such as the widely used Emax model, are used to describe relationships that are bounded above and below. We propose methods for estimating the parameters of a dose-response model by meta-analysis of summary data from the results of randomized controlled trials of a drug, in which each trial uses multiple doses of the drug of interest (possibly including dose 0 or placebo). We assume that, for each randomized arm of each trial, the mean and standard error of a continuous response measure and the corresponding allocated dose are available. We consider weighted least squares fitting of the model to the mean and dose pairs from all arms of all studies, and a two-stage procedure in which scalar inverse-variance meta-analysis is performed at each dose, and the dose-response model is fitted to the results by weighted least squares. We then compare these with two further methods inspired by network meta-analysis that fit the model to the contrasts between doses. We illustrate the methods by estimating the parameters of the Emax model to a collection of multi-arm, multiple-dose, randomized controlled trials of alogliptin, a drug for the management of diabetes mellitus, and further examine the properties of the four methods with sensitivity analyses and a simulation study. We find that all four methods produce broadly comparable point estimates for the parameters of most interest, but a single-stage method based on contrasts between doses produces the most appropriate confidence intervals. Although simpler methods may have pragmatic advantages, such as the use of standard software for scalar meta-analysis, more sophisticated methods are nevertheless preferable for their advantages in estimation.

  3. Comparison of prosthetic models produced by traditional and additive manufacturing methods

    PubMed Central

    Park, Jin-Young; Kim, Hae-Young; Kim, Ji-Hwan; Kim, Jae-Hong

    2015-01-01

    PURPOSE The purpose of this study was to verify the clinical-feasibility of additive manufacturing by comparing the accuracy of four different manufacturing methods for metal coping: the conventional lost wax technique (CLWT); subtractive methods with wax blank milling (WBM); and two additive methods, multi jet modeling (MJM), and micro-stereolithography (Micro-SLA). MATERIALS AND METHODS Thirty study models were created using an acrylic model with the maxillary upper right canine, first premolar, and first molar teeth. Based on the scan files from a non-contact blue light scanner (Identica; Medit Co. Ltd., Seoul, Korea), thirty cores were produced using the WBM, MJM, and Micro-SLA methods, respectively, and another thirty frameworks were produced using the CLWT method. To measure the marginal and internal gap, the silicone replica method was adopted, and the silicone images obtained were evaluated using a digital microscope (KH-7700; Hirox, Tokyo, Japan) at 140X magnification. Analyses were performed using two-way analysis of variance (ANOVA) and Tukey post hoc test (α=.05). RESULTS The mean marginal gaps and internal gaps showed significant differences according to tooth type (P<.001 and P<.001, respectively) and manufacturing method (P<.037 and P<.001, respectively). Micro-SLA did not show any significant difference from CLWT regarding mean marginal gap compared to the WBM and MJM methods. CONCLUSION The mean values of gaps resulting from the four different manufacturing methods were within a clinically allowable range, and, thus, the clinical use of additive manufacturing methods is acceptable as an alternative to the traditional lost wax-technique and subtractive manufacturing. PMID:26330976

  4. Numerical system utilising a Monte Carlo calculation method for accurate dose assessment in radiation accidents.

    PubMed

    Takahashi, F; Endo, A

    2007-01-01

    A system utilising radiation transport codes has been developed to derive accurate dose distributions in a human body for radiological accidents. A suitable model is quite essential for a numerical analysis. Therefore, two tools were developed to setup a 'problem-dependent' input file, defining a radiation source and an exposed person to simulate the radiation transport in an accident with the Monte Carlo calculation codes-MCNP and MCNPX. Necessary resources are defined by a dialogue method with a generally used personal computer for both the tools. The tools prepare human body and source models described in the input file format of the employed Monte Carlo codes. The tools were validated for dose assessment in comparison with a past criticality accident and a hypothesized exposure.

  5. Methods used to calculate doses resulting from inhalation of Capstone depleted uranium aerosols.

    PubMed

    Miller, Guthrie; Cheng, Yung Sung; Traub, Richard J; Little, Tom T; Guilmette, Raymond A

    2009-03-01

    The methods used to calculate radiological and toxicological doses to hypothetical persons inside either a U.S. Army Abrams tank or Bradley Fighting Vehicle that has been perforated by depleted uranium munitions are described. Data from time- and particle-size-resolved measurements of depleted uranium aerosol as well as particle-size-resolved measurements of aerosol solubility in lung fluids for aerosol produced in the breathing zones of the hypothetical occupants were used. The aerosol was approximated as a mixture of nine monodisperse (single particle size) components corresponding to particle size increments measured by the eight stages plus the backup filter of the cascade impactors used. A Markov Chain Monte Carlo Bayesian analysis technique was employed, which straightforwardly calculates the uncertainties in doses. Extensive quality control checking of the various computer codes used is described.

  6. Low Dose PET Image Reconstruction with Total Variation Using Alternating Direction Method

    PubMed Central

    Yu, Xingjian; Wang, Chenye; Hu, Hongjie; Liu, Huafeng

    2016-01-01

    In this paper, a total variation (TV) minimization strategy is proposed to overcome the problem of sparse spatial resolution and large amounts of noise in low dose positron emission tomography (PET) imaging reconstruction. Two types of objective function were established based on two statistical models of measured PET data, least-square (LS) TV for the Gaussian distribution and Poisson-TV for the Poisson distribution. To efficiently obtain high quality reconstructed images, the alternating direction method (ADM) is used to solve these objective functions. As compared with the iterative shrinkage/thresholding (IST) based algorithms, the proposed ADM can make full use of the TV constraint and its convergence rate is faster. The performance of the proposed approach is validated through comparisons with the expectation-maximization (EM) method using synthetic and experimental biological data. In the comparisons, the results of both LS-TV and Poisson-TV are taken into consideration to find which models are more suitable for PET imaging, in particular low-dose PET. To evaluate the results quantitatively, we computed bias, variance, and the contrast recovery coefficient (CRC) and drew profiles of the reconstructed images produced by the different methods. The results show that both Poisson-TV and LS-TV can provide a high visual quality at a low dose level. The bias and variance of the proposed LS-TV and Poisson-TV methods are 20% to 74% less at all counting levels than those of the EM method. Poisson-TV gives the best performance in terms of high-accuracy reconstruction with the lowest bias and variance as compared to the ground truth (14.3% less bias and 21.9% less variance). In contrast, LS-TV gives the best performance in terms of the high contrast of the reconstruction with the highest CRC. PMID:28005929

  7. Best Practices in Stability Indicating Method Development and Validation for Non-clinical Dose Formulations.

    PubMed

    Henry, Teresa R; Penn, Lara D; Conerty, Jason R; Wright, Francesca E; Gorman, Gregory; Pack, Brian W

    2016-11-01

    Non-clinical dose formulations (also known as pre-clinical or GLP formulations) play a key role in early drug development. These formulations are used to introduce active pharmaceutical ingredients (APIs) into test organisms for both pharmacokinetic and toxicological studies. Since these studies are ultimately used to support dose and safety ranges in human studies, it is important to understand not only the concentration and PK/PD of the active ingredient but also to generate safety data for likely process impurities and degradation products of the active ingredient. As such, many in the industry have chosen to develop and validate methods which can accurately detect and quantify the active ingredient along with impurities and degradation products. Such methods often provide trendable results which are predictive of stability, thus leading to the name; stability indicating methods. This document provides an overview of best practices for those choosing to include development and validation of such methods as part of their non-clinical drug development program. This document is intended to support teams who are either new to stability indicating method development and validation or who are less familiar with the requirements of validation due to their position within the product development life cycle.

  8. Does the Addition of Involved Field Radiotherapy to High-Dose Chemotherapy and Stem Cell Transplantation Improve Outcomes for Patients With Relapsed/Refractory Hodgkin Lymphoma?

    SciTech Connect

    Kahn, Shannon; Flowers, Christopher; Xu Zhiheng; Esiashvili, Natia

    2011-09-01

    Purpose: To evaluate the value of adding involved field radiotherapy (IFRT) to patients with relapsed/refractory Hodgkin lymphoma (HL) undergoing high-dose chemotherapy (HDCT) and stem cell transplantation (SCT). Methods and Materials: Ninety-two patients with relapsed/refractory HL undergoing HDCT and SCT from 1995 to 2008 were analyzed in a case-control design. Forty-six HL patients treated with IFRT within 2 months of SCT were matched to 46 HL patients who did not receive IFRT based on age, stage at relapse, timing of relapse, histology, and year of SCT. All were evaluated for response, survival, and toxicity with a median followup of 63.5 months. Results: There was a trend for better disease control in patients receiving IFRT. Specifically, 10/46 IFRT patients (22%) relapsed/progressed after SCT compared with 17/46 control patients (37%). Of the failures after IFRT, 70% were inside the radiation field, all in sites of bulky disease. In patients with nonbulky disease, IFRT also resulted in significantly improved outcomes (failure rate 6% vs. 33%, respectively). When stratified by disease bulk, the use of IFRT was found to significantly improve DFS (p = 0.032), but did not affect OS. In addition, IFRT and nonbulky disease were found to be positive prognostic indicators for DFS with hazard ratios of 0.357 (p = 0.032) and 0.383 (p = 0.034), respectively. Grade IV/V toxicities were significantly higher in the IFRT vs. non-IFRT group (28% vs. 2%; p < 0.001), observed only in patients receiving a busulfan-based conditioning regimen. Conclusion: Patients with refractory or relapsed HL undergoing HDCT and SCT have a high risk of relapse in sites of prior disease involvement, especially in sites of bulky disease. The use of IFRT is associated with a lower risk of disease progression in these sites; however bulky disease sites are still difficult to control. Toxicity risk is significant, particularly when busulfan-based conditioning is combined with IFRT, and alternative

  9. Feasibility of a Multigroup Deterministic Solution Method for 3D Radiotherapy Dose Calculations

    PubMed Central

    Vassiliev, Oleg N.; Wareing, Todd A.; Davis, Ian M.; McGhee, John; Barnett, Douglas; Horton, John L.; Gifford, Kent; Failla, Gregory; Titt, Uwe; Mourtada, Firas

    2008-01-01

    Purpose To investigate the potential of a novel deterministic solver, Attila, for external photon beam radiotherapy dose calculations. Methods and Materials Two hypothetical cases for prostate and head and neck cancer photon beam treatment plans were calculated using Attila and EGSnrc Monte Carlo simulations. Open beams were modeled as isotropic photon point sources collimated to specified field sizes (100 cm SSD). The sources had a realistic energy spectrum calculated by Monte Carlo for a Varian Clinac 2100 operated in a 6MV photon mode. The Attila computational grids consisted of 106,000 elements, or 424,000 spatial degrees of freedom, for the prostate case, and 123,000 tetrahedral elements, or 492,000 spatial degrees of freedom, for the head and neck cases. Results For both cases, results demonstrate excellent agreement between Attila and EGSnrc in all areas, including the build-up regions, near heterogeneities, and at the beam penumbra. Dose agreement for 99% of the voxels was within 3% (relative point-wise difference) or 3mm distance-to-agreement criterion. Localized differences between the Attila and EGSnrc results were observed at bone and soft tissue interfaces, and are attributable to the effect of voxel material homogenization in calculating dose-to-medium in EGSnrc. For both cases, Attila calculation times were under 20 CPU minutes on a single 2.2 GHz AMD Opteron processor. Conclusions The methods in Attila have the potential to be the basis for an efficient dose engine for patient specific treatment planning, providing accuracy similar to that obtained by Monte Carlo. PMID:18722273

  10. Additional notes on clinical repeated-dose pharmacokinetic trials applying a peak-and-trough sampling design to estimate oral clearance.

    PubMed

    Takaai, Mari; Kayano, Yuichiro; Shimizu, Takako; Taguchi, Masato; Hashimoto, Yukiya

    2008-01-01

    In the previous study, we performed a simulation of a clinical pharmacokinetic trial, in which blood was sampled at two time points corresponding to the peak concentration (C(peak)) and trough concentration (C(trough)) following repetitive oral administration at the dose, D, and dosing interval, tau. The approximate oral clearance (CL/F(approx)), estimated as 2 x D/(C(peak) x tau+C(trough) x tau), is accurate for drugs with an elimination half-life comparative to or longer than tau; however, it was suggested that we might not use CL/F(approx) for drugs with a considerably short elimination half-life relative to tau. In the present study, we evaluated the accuracy of the alternative oral clearance (CL/F(exp)) estimated by the simple monoexponential model. In contrast to CL/F(approx), CL/F(exp) was accurate for drugs with a short elimination half-life relative to tau. The present finding in conjunction with our previous study suggested that the peak-and-trough sampling design is promising for the clinical repeated-dose pharmacokinetic trial for drugs with not only slow but also rapid elimination from the body. We think that the accuracy and precision of the two analysis methods to estimate oral clearance (CL/F(approx) and CL/F(exp)) for a target drug should be evaluated carefully before and after a real clinical trial.

  11. The Capacity Profile: A Method to Classify Additional Care Needs in Children with Neurodevelopmental Disabilities

    ERIC Educational Resources Information Center

    Meester-Delver, Anke; Beelen, Anita; Hennekam, Raoul; Nollet, Frans; Hadders-Algra, Mijna

    2007-01-01

    The aim of this study was to determine the interrater reliability and stability over time of the Capacity Profile (CAP). The CAP is a standardized method for classifying additional care needs indicated by current impairments in five domains of body functions: physical health, neuromusculoskeletal and movement-related, sensory, mental, and voice…

  12. A Modified Time-Delay Addition Method to Extract Resistive Leakage Current of MOSA

    NASA Astrophysics Data System (ADS)

    Khodsuz, Masume; Mirzaie, Mohammad

    2016-12-01

    Metal oxide surge arresters are one of the most important equipment for power system protection against switching and lightning over-voltages. High-energy stresses and environmental features are the main factors which degrade surge arresters. In order to verify surge arresters good condition, their monitoring is necessary. The majority of surge arrester monitoring techniques is based on total leakage current decomposition of their capacitive and resistive components. This paper introduces a new approach based on time-delay addition method to extract the resistive current from the total leakage current without measuring voltage signal. Surge arrester model for calculating leakage current has been performed in ATP-EMTP. In addition, the signal processing has been done using MATLAB software. To show the accuracy of the proposed method, experimental tests have been performed to extract resistive leakage current by the proposed method.

  13. Reducing the matrix effects in chemical analysis: fusion of isotope dilution and standard addition methods

    NASA Astrophysics Data System (ADS)

    Pagliano, Enea; Meija, Juris

    2016-04-01

    The combination of isotope dilution and mass spectrometry has become an ubiquitous tool of chemical analysis. Often perceived as one of the most accurate methods of chemical analysis, it is not without shortcomings. Current isotope dilution equations are not capable of fully addressing one of the key problems encountered in chemical analysis: the possible effect of sample matrix on measured isotope ratios. The method of standard addition does compensate for the effect of sample matrix by making sure that all measured solutions have identical composition. While it is impossible to attain such condition in traditional isotope dilution, we present equations which allow for matrix-matching between all measured solutions by fusion of isotope dilution and standard addition methods.

  14. Method for the evaluation of a average glandular dose in mammography

    SciTech Connect

    Okunade, Akintunde Akangbe

    2006-04-15

    This paper concerns a method for accurate evaluation of average glandular dose (AGD) in mammography. At different energies, the interactions of photons with tissue are not uniform. Thus, optimal accuracy in the estimation of AGD is achievable when the evaluation is carried out using the normalized glandular dose values, g(x,E), that are determined for each (monoenergetic) x-ray photon energy, E, compressed breast thickness (CBT), x, breast glandular composition, and data on photon energy distribution of the exact x-ray beam used in breast imaging. A generalized model for the values of g(x,E) that is for any arbitrary CBT ranging from 2 to 9 cm (with values that are not whole numbers inclusive, say, 4.2 cm) was developed. Along with other dosimetry formulations, this was integrated into a computer software program, GDOSE.FOR, that was developed for the evaluation of AGD received from any x-ray tube/equipment (irrespective of target-filter combination) of up to 50 kVp. Results are presented which show that the implementation of GDOSE.FOR yields values of normalized glandular dose that are in good agreement with values obtained from methodologies reported earlier in the literature. With the availability of a portable device for real-time acquisition of spectra, the model and computer software reported in this work provide for the routine evaluation of AGD received by a specific woman of known age and CBT.

  15. Pediatric stroke and transcranial direct current stimulation: methods for rational individualized dose optimization

    PubMed Central

    Gillick, Bernadette T.; Kirton, Adam; Carmel, Jason B.; Minhas, Preet; Bikson, Marom

    2014-01-01

    Background: Transcranial direct current stimulation (tDCS) has been investigated mainly in adults and doses may not be appropriate in pediatric applications. In perinatal stroke where potential applications are promising, rational adaptation of dosage for children remains under investigation. Objective: Construct child-specific tDCS dosing parameters through case study within a perinatal stroke tDCS safety and feasibility trial. Methods: 10-year-old subject with a diagnosis of presumed perinatal ischemic stroke and hemiparesis was identified. T1 magnetic resonance imaging (MRI) scans used to derive computerized model for current flow and electrode positions. Workflow using modeling results and consideration of dosage in previous clinical trials was incorporated. Prior ad hoc adult montages vs. de novo optimized montages provided distinct risk benefit analysis. Approximating adult dose required consideration of changes in both peak brain current flow and distribution which further tradeoff between maximizing efficacy and adding safety factors. Electrode size, position, current intensity, compliance voltage, and duration were controlled independently in this process. Results: Brain electric fields modeled and compared to values previously predicted models (Datta et al., 2011; Minhas et al., 2012). Approximating conservative brain current flow patterns and intensities used in previous adult trials for comparable indications, the optimal current intensity established was 0.7 mA for 10 min with a tDCS C3/C4 montage. Specifically 0.7 mA produced comparable peak brain current intensity of an average adult receiving 1.0 mA. Electrode size of 5 × 7 cm2 with 1.0 mA and low-voltage tDCS was employed to maximize tolerability. Safety and feasibility confirmed with subject tolerating the session well and no serious adverse events. Conclusion: Rational approaches to dose customization, with steps informed by computational modeling, may improve guidance for pediatric stroke t

  16. Projection domain denoising method based on dictionary learning for low-dose CT image reconstruction.

    PubMed

    Zhang, Haiyan; Zhang, Liyi; Sun, Yunshan; Zhang, Jingyu

    2015-01-01

    Reducing X-ray tube current is one of the widely used methods for decreasing the radiation dose. Unfortunately, the signal-to-noise ratio (SNR) of the projection data degrades simultaneously. To improve the quality of reconstructed images, a dictionary learning based penalized weighted least-squares (PWLS) approach is proposed for sinogram denoising. The weighted least-squares considers the statistical characteristic of noise and the penalty models the sparsity of sinogram based on dictionary learning. Then reconstruct CT image using filtered back projection (FBP) algorithm from the denoised sinogram. The proposed method is particularly suitable for the projection data with low SNR. Experimental results show that the proposed method can get high-quality CT images when the signal to noise ratio of projection data declines sharply.

  17. 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

  18. Task-based image quality evaluation of iterative reconstruction methods for low dose CT using computer simulations

    NASA Astrophysics Data System (ADS)

    Xu, Jingyan; Fuld, Matthew K.; Fung, George S. K.; Tsui, Benjamin M. W.

    2015-04-01

    Iterative reconstruction (IR) methods for x-ray CT is a promising approach to improve image quality or reduce radiation dose to patients. The goal of this work was to use task based image quality measures and the channelized Hotelling observer (CHO) to evaluate both analytic and IR methods for clinical x-ray CT applications. We performed realistic computer simulations at five radiation dose levels, from a clinical reference low dose D0 to 25% D0. A fixed size and contrast lesion was inserted at different locations into the liver of the XCAT phantom to simulate a weak signal. The simulated data were reconstructed on a commercial CT scanner (SOMATOM Definition Flash; Siemens, Forchheim, Germany) using the vendor-provided analytic (WFBP) and IR (SAFIRE) methods. The reconstructed images were analyzed by CHOs with both rotationally symmetric (RS) and rotationally oriented (RO) channels, and with different numbers of lesion locations (5, 10, and 20) in a signal known exactly (SKE), background known exactly but variable (BKEV) detection task. The area under the receiver operating characteristic curve (AUC) was used as a summary measure to compare the IR and analytic methods; the AUC was also used as the equal performance criterion to derive the potential dose reduction factor of IR. In general, there was a good agreement in the relative AUC values of different reconstruction methods using CHOs with RS and RO channels, although the CHO with RO channels achieved higher AUCs than RS channels. The improvement of IR over analytic methods depends on the dose level. The reference dose level D0 was based on a clinical low dose protocol, lower than the standard dose due to the use of IR methods. At 75% D0, the performance improvement was statistically significant (p < 0.05). The potential dose reduction factor also depended on the detection task. For the SKE/BKEV task involving 10 lesion locations, a dose reduction of at least 25% from D0 was achieved.

  19. Shutdown Dose Rate Analysis Using the Multi-Step CADIS Method

    SciTech Connect

    Ibrahim, Ahmad M.; Peplow, Douglas E.; Peterson, Joshua L.; Grove, Robert E.

    2015-01-01

    The Multi-Step Consistent Adjoint Driven Importance Sampling (MS-CADIS) hybrid Monte Carlo (MC)/deterministic radiation transport method was proposed to speed up the shutdown dose rate (SDDR) neutron MC calculation using an importance function that represents the neutron importance to the final SDDR. This work applied the MS-CADIS method to the ITER SDDR benchmark problem. The MS-CADIS method was also used to calculate the SDDR uncertainty resulting from uncertainties in the MC neutron calculation and to determine the degree of undersampling in SDDR calculations because of the limited ability of the MC method to tally detailed spatial and energy distributions. The analysis that used the ITER benchmark problem compared the efficiency of the MS-CADIS method to the traditional approach of using global MC variance reduction techniques for speeding up SDDR neutron MC calculation. Compared to the standard Forward-Weighted-CADIS (FW-CADIS) method, the MS-CADIS method increased the efficiency of the SDDR neutron MC calculation by 69%. The MS-CADIS method also increased the fraction of nonzero scoring mesh tally elements in the space-energy regions of high importance to the final SDDR.

  20. Shutdown Dose Rate Analysis Using the Multi-Step CADIS Method

    DOE PAGES

    Ibrahim, Ahmad M.; Peplow, Douglas E.; Peterson, Joshua L.; ...

    2015-01-01

    The Multi-Step Consistent Adjoint Driven Importance Sampling (MS-CADIS) hybrid Monte Carlo (MC)/deterministic radiation transport method was proposed to speed up the shutdown dose rate (SDDR) neutron MC calculation using an importance function that represents the neutron importance to the final SDDR. This work applied the MS-CADIS method to the ITER SDDR benchmark problem. The MS-CADIS method was also used to calculate the SDDR uncertainty resulting from uncertainties in the MC neutron calculation and to determine the degree of undersampling in SDDR calculations because of the limited ability of the MC method to tally detailed spatial and energy distributions. The analysismore » that used the ITER benchmark problem compared the efficiency of the MS-CADIS method to the traditional approach of using global MC variance reduction techniques for speeding up SDDR neutron MC calculation. Compared to the standard Forward-Weighted-CADIS (FW-CADIS) method, the MS-CADIS method increased the efficiency of the SDDR neutron MC calculation by 69%. The MS-CADIS method also increased the fraction of nonzero scoring mesh tally elements in the space-energy regions of high importance to the final SDDR.« less

  1. Methods of cracking a crude product to produce additional crude products

    DOEpatents

    Mo, Weijian; Roes, Augustinus Wilhelmus Maria; Nair, Vijay

    2009-09-08

    A method for producing a crude product is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce one or more crude products. At least one of the crude products has a boiling range distribution from 38.degree. C. and 343.degree. C. as determined by ASTM Method D5307. The crude product having the boiling range distribution from 38.degree. C. and 343.degree. C. is catalytically cracked to produce one or more additional crude products. At least one of the additional crude products is a second gas stream. The second gas stream has a boiling point of at most 38.degree. C. at 0.101 MPa.

  2. The method of manufacture of nylon dental partially removable prosthesis using additive technologies

    NASA Astrophysics Data System (ADS)

    Kashapov, R. N.; Korobkina, A. I.; Platonov, E. V.; Saleeva, G. T.

    2014-12-01

    The article is devoted to the topic of creating new methods of dental prosthesis. The aim of this work is to investigate the possibility of using additive technology to create nylon prosthesis. As a result of experimental studies, was made a sample of nylon partially removable prosthesis using 3D printing has allowed to simplify, accelerate and reduce the coat of manufacturing high-precision nylon dentures.

  3. Hybrid Residual Flexibility/Mass-Additive Method for Structural Dynamic Testing

    NASA Technical Reports Server (NTRS)

    Tinker, M. L.

    2003-01-01

    A large fixture was designed and constructed for modal vibration testing of International Space Station elements. This fixed-base test fixture, which weighs thousands of pounds and is anchored to a massive concrete floor, initially utilized spherical bearings and pendulum mechanisms to simulate Shuttle orbiter boundary constraints for launch of the hardware. Many difficulties were encountered during a checkout test of the common module prototype structure, mainly due to undesirable friction and excessive clearances in the test-article-to-fixture interface bearings. Measured mode shapes and frequencies were not representative of orbiter-constrained modes due to the friction and clearance effects in the bearings. As a result, a major redesign effort for the interface mechanisms was undertaken. The total cost of the fixture design, construction and checkout, and redesign was over $2 million. Because of the problems experienced with fixed-base testing, alternative free-suspension methods were studied, including the residual flexibility and mass-additive approaches. Free-suspension structural dynamics test methods utilize soft elastic bungee cords and overhead frame suspension systems that are less complex and much less expensive than fixed-base systems. The cost of free-suspension fixturing is on the order of tens of thousands of dollars as opposed to millions, for large fixed-base fixturing. In addition, free-suspension test configurations are portable, allowing modal tests to be done at sites without modal test facilities. For example, a mass-additive modal test of the ASTRO-1 Shuttle payload was done at the Kennedy Space Center launch site. In this Technical Memorandum, the mass-additive and residual flexibility test methods are described in detail. A discussion of a hybrid approach that combines the best characteristics of each method follows and is the focus of the study.

  4. A Novel Method of Estimating Dose Responses for Polymer Gels Using Texture Analysis of Scanning Electron Microscopy Images

    PubMed Central

    Shih, Cheng-Ting; Hsu, Jui-Ting; Han, Rou-Ping; Hsieh, Bor-Tsung; Chang, Shu-Jun; Wu, Jay

    2013-01-01

    Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM) images. The modified N-isopropyl-acrylamide (NIPAM) gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM). The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R2 value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were −7.60%, 5.80%, 2.53%, and −0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection. PMID:23843998

  5. A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

    PubMed

    Shih, Cheng-Ting; Hsu, Jui-Ting; Han, Rou-Ping; Hsieh, Bor-Tsung; Chang, Shu-Jun; Wu, Jay

    2013-01-01

    Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM) images. The modified N-isopropyl-acrylamide (NIPAM) gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM). The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2) value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

  6. [Bootstrap method-based estimation on the confidence interval for additive interaction in cohort studies].

    PubMed

    Pan, Jin-ren; Chen, Kun

    2010-07-01

    Interaction assessment is an important step in epidemiological analysis. When etiological study is carried out, the logarithmic models such as logistic model or Cox proportional hazard model are commonly used to estimate the independent effects of the risk factors. However, estimating interaction between risk factors by the regression coefficient of the product term is on multiplicative scale, and for public-health purposes, it is supposed to be on additive scale or departure from additivity. This paper illustrates with a example of cohort study by fitting Cox proportional hazard model to estimate three measures for additive interaction which presented by Rothman. Adopting the S-Plus application with a built-in Bootstrap function, it is convenient to estimate the confidence interval for additive interaction. Furthermore, this method can avoid the exaggerated estimation by using ORs in a cohort study to gain better precision. When using the complex combination models between additive interaction and multiplicative interaction, it is reasonable to choose the former one when the result is inconsistent.

  7. Validating a nondestructive optical method for apportioning colored particulate matter into black carbon and additional components

    PubMed Central

    Yan, Beizhan; Kennedy, Daniel; Miller, Rachel L.; Cowin, James P.; Jung, Kyung-hwa; Perzanowski, Matt; Balletta, Marco; Perera, Federica P.; Kinney, Patrick L.; Chillrud, Steven N.

    2011-01-01

    Exposure of black carbon (BC) is associated with a variety of adverse health outcomes. A number of optical methods for estimating BC on Teflon filters have been adopted but most assume all light absorption is due to BC while other sources of colored particulate matter exist. Recently, a four-wavelength-optical reflectance measurement for distinguishing second hand cigarette smoke (SHS) from soot-BC was developed (Brook et al., 2010; Lawless et al., 2004). However, the method has not been validated for soot-BC nor SHS and little work has been done to look at the methodological issues of the optical reflectance measurements for samples that could have SHS, BC, and other colored particles. We refined this method using a lab-modified integrating sphere with absorption measured continuously from 350 nm to 1000 nm. Furthermore, we characterized the absorption spectrum of additional components of particulate matter (PM) on PM2.5 filters including ammonium sulfate, hematite, goethite, and magnetite. Finally, we validate this method for BC by comparison to other standard methods. Use of synthesized data indicates that it is important to optimize the choice of wavelengths to minimize computational errors as additional components (more than 2) are added to the apportionment model of colored components. We found that substantial errors are introduced when using 4 wavelengths suggested by Lawless et al. to quantify four substances, while an optimized choice of wavelengths can reduce model-derived error from over 10% to less than 2%. For environmental samples, the method was sensitive for estimating airborne levels of BC and SHS, but not mass loadings of iron oxides and sulfate. Duplicate samples collected in NYC show high reproducibility (points consistent with a 1:1 line, R2 = 0.95). BC data measured by this method were consistent with those measured by other optical methods, including Aethalometer and Smoke-stain Reflectometer (SSR); although the SSR looses sensitivity at

  8. Validating a nondestructive optical method for apportioning colored particulate matter into black carbon and additional components.

    PubMed

    Yan, Beizhan; Kennedy, Daniel; Miller, Rachel L; Cowin, James P; Jung, Kyung-Hwa; Perzanowski, Matt; Balletta, Marco; Perera, Federica P; Kinney, Patrick L; Chillrud, Steven N

    2011-12-01

    Exposure of black carbon (BC) is associated with a variety of adverse health outcomes. A number of optical methods for estimating BC on Teflon filters have been adopted but most assume all light absorption is due to BC while other sources of colored particulate matter exist. Recently, a four-wavelength-optical reflectance measurement for distinguishing second hand cigarette smoke (SHS) from soot-BC was developed (Brook et al., 2010; Lawless et al., 2004). However, the method has not been validated for soot-BC nor SHS and little work has been done to look at the methodological issues of the optical reflectance measurements for samples that could have SHS, BC, and other colored particles. We refined this method using a lab-modified integrating sphere with absorption measured continuously from 350 nm to 1000 nm. Furthermore, we characterized the absorption spectrum of additional components of particulate matter (PM) on PM(2.5) filters including ammonium sulfate, hematite, goethite, and magnetite. Finally, we validate this method for BC by comparison to other standard methods. Use of synthesized data indicates that it is important to optimize the choice of wavelengths to minimize computational errors as additional components (more than 2) are added to the apportionment model of colored components. We found that substantial errors are introduced when using 4 wavelengths suggested by Lawless et al. to quantify four substances, while an optimized choice of wavelengths can reduce model-derived error from over 10% to less than 2%. For environmental samples, the method was sensitive for estimating airborne levels of BC and SHS, but not mass loadings of iron oxides and sulfate. Duplicate samples collected in NYC show high reproducibility (points consistent with a 1:1 line, R(2) = 0.95). BC data measured by this method were consistent with those measured by other optical methods, including Aethalometer and Smoke-stain Reflectometer (SSR); although the SSR looses sensitivity at

  9. Validating a nondestructive optical method for apportioning colored particulate matter into black carbon and additional components

    NASA Astrophysics Data System (ADS)

    Yan, Beizhan; Kennedy, Daniel; Miller, Rachel L.; Cowin, James P.; Jung, Kyung-hwa; Perzanowski, Matt; Balletta, Marco; Perera, Federica P.; Kinney, Patrick L.; Chillrud, Steven N.

    2011-12-01

    Exposure of black carbon (BC) is associated with a variety of adverse health outcomes. A number of optical methods for estimating BC on Teflon filters have been adopted but most assume all light absorption is due to BC while other sources of colored particulate matter exist. Recently, a four-wavelength-optical reflectance measurement for distinguishing second hand cigarette smoke (SHS) from soot-BC was developed (Brook et al., 2010; Lawless et al., 2004). However, the method has not been validated for soot-BC nor SHS and little work has been done to look at the methodological issues of the optical reflectance measurements for samples that could have SHS, BC, and other colored particles. We refined this method using a lab-modified integrating sphere with absorption measured continuously from 350 nm to 1000 nm. Furthermore, we characterized the absorption spectrum of additional components of particulate matter (PM) on PM 2.5 filters including ammonium sulfate, hematite, goethite, and magnetite. Finally, we validate this method for BC by comparison to other standard methods. Use of synthesized data indicates that it is important to optimize the choice of wavelengths to minimize computational errors as additional components (more than 2) are added to the apportionment model of colored components. We found that substantial errors are introduced when using 4 wavelengths suggested by Lawless et al. to quantify four substances, while an optimized choice of wavelengths can reduce model-derived error from over 10% to less than 2%. For environmental samples, the method was sensitive for estimating airborne levels of BC and SHS, but not mass loadings of iron oxides and sulfate. Duplicate samples collected in NYC show high reproducibility (points consistent with a 1:1 line, R2 = 0.95). BC data measured by this method were consistent with those measured by other optical methods, including Aethalometer and Smoke-stain Reflectometer (SSR); although the SSR looses sensitivity at

  10. Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2013-07-09

    A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

  11. [New dosimetry system based on the thermoluminescence method for evaluation of ionizing radiation doses to workers of the health centers].

    PubMed

    Urban, Paweł; Skubacz, Krystian

    2015-01-01

    In different areas of industry, science and in the greater extend medicine, plenty of devices intended for production of ionizing radiation or containing sources of such radiation found application. Such situation causes the necessity to control such kind of hazards. Currently, the most popular technique for detection of ionizing radiation is the method based on the thermoluminescence phenomena. Within the frame of this work, a new Panasonic's dosimetry system based on thermoluminescence dosimeters, intended for assessment of doses in mixed radiation fields of various energies is presented. In addition, the measured dosimetry quantities and problems connected with monitoring of radiation hazard in mixed fields (commonly present in medical sector) are characterized. In orderto verify measurement capabilities of the new system the irradiations of dosimeters with ionizing radiation of different energies have been done.

  12. 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.

  13. A Preferable Method for the Formation of Vesicles from Lamellar Liquid Crystals Using Chemical Additives.

    PubMed

    Enomoto, Yasutaka; Imai, Yoko; Tajima, Kazuo

    2017-01-01

    We present a method for vesicle formation from lamellar liquid crystals (LCs) using a cationic amphiphilic substance, namely 2-hydroxyethyl di(alkanol)oxyethyl methylammonium methylsulfate (DEAE). Vesicle formation from the DEAE lamellar dispersion occurred via a two-step chemical addition. This method required neither additional mechanical energy nor the use of special solvents. The transition was solubilized using an organic substance (e.g., limonene) in the lamellar DEAE LC, after which, a small amount of inorganic salt was added to the solubilized lamellar LC dispersion with gentle stirring. The viscosity of the DEAE dispersion following salt addition decreased sharply from 10(5) mPa·s to 10(2) mPa·s, and the DEAE dispersion was converted into a high fluidity liquid. Several organic substances were examined as potential solubilizates to initiate the lamellar-vesicle transition. Inorganic salts were also examined as transition triggers using various types of electrolytes; only neutral salts were effective as trigger additives. Dissociation of inorganic salts yielded anions, which inserted between the DEAE bilayer membranes and induced OH(-) ion exchange. In addition, a number of cations simultaneously formed ion pairs with the DEAE counter ions (CH3SO4(-) ions). However, as the amount of solubilized organic substances in the DEAE bilayer membrane decreased over time, the vesicles were transformed into lamellar LCs once again. The DEAE states in each step were measured by monitoring the zeta potential, pH, viscosity, and by examination of scanning electron microscopy and atomic force microscopy images. A possible molecular mechanism for the lamellar-vesicle transition of DEAE was proposed.

  14. Comparison of simple additive weighting (SAW) and composite performance index (CPI) methods in employee remuneration determination

    NASA Astrophysics Data System (ADS)

    Karlitasari, L.; Suhartini, D.; Benny

    2017-01-01

    The process of determining the employee remuneration for PT Sepatu Mas Idaman currently are still using Microsoft Excel-based spreadsheet where in the spreadsheet there is the value of criterias that must be calculated for every employee. This can give the effect of doubt during the assesment process, therefore resulting in the process to take much longer time. The process of employee remuneration determination is conducted by the assesment team based on some criterias that have been predetermined. The criteria used in the assessment process are namely the ability to work, human relations, job responsibility, discipline, creativity, work, achievement of targets, and absence. To ease the determination of employee remuneration to be more efficient and effective, the Simple Additive Weighting (SAW) method is used. SAW method can help in decision making for a certain case, and the calculation that generates the greatest value will be chosen as the best alternative. Other than SAW, also by using another method was the CPI method which is one of the calculating method in decision making based on performance index. Where SAW method was more faster by 89-93% compared to CPI method. Therefore it is expected that this application can be an evaluation material for the need of training and development for employee performances to be more optimal.

  15. MO-E-17A-04: Size-Specific Dose Estimate (SSDE) Provides a Simple Method to Calculate Organ Dose for Pediatric CT Examinations

    SciTech Connect

    Moore, B; Brady, S; Kaufman, R; Mirro, A

    2014-06-15

    Purpose: Investigate the correlation of SSDE with organ dose in a pediatric population. Methods: Four anthropomorphic phantoms, representing a range of pediatric body habitus, were scanned with MOSFET dosimeters placed at 23 organ locations to determine absolute organ dosimetry. Phantom organ dosimetry was divided by phantom SSDE to determine correlation between organ dose and SSDE. Correlation factors were then multiplied by patient SSDE to estimate patient organ dose. Patient demographics consisted of 352 chest and 241 abdominopelvic CT examinations, 22 ± 15 kg (range 5−55 kg) mean weight, and 6 ± 5 years (range 4 mon to 23 years) mean age. Patient organ dose estimates were compared to published pediatric Monte Carlo study results. Results: Phantom effective diameters were matched with patient population effective diameters to within 4 cm. 23 organ correlation factors were determined in the chest and abdominopelvic region across nine pediatric weight subcategories. For organs fully covered by the scan volume, correlation in the chest (average 1.1; range 0.7−1.4) and abdominopelvic (average 0.9; range 0.7−1.3) was near unity. For organs that extended beyond the scan volume (i.e., skin, bone marrow, and bone surface), correlation was determined to be poor (average 0.3; range: 0.1−0.4) for both the chest and abdominopelvic regions, respectively. Pediatric organ dosimetry was compared to published values and was found to agree in the chest to better than an average of 5% (27.6/26.2) and in the abdominopelvic region to better than 2% (73.4/75.0). Conclusion: Average correlation of SSDE and organ dosimetry was found to be better than ± 10% for fully covered organs within the scan volume. This study provides a list of organ dose correlation factors for the chest and abdominopelvic regions, and describes a simple methodology to estimate individual pediatric patient organ dose based on patient SSDE.

  16. Testing for Additivity in Chemical Mixtures Using a Fixed-Ratio Ray Design and Statistical Equivalence Testing Methods

    EPA Science Inventory

    Fixed-ratio ray designs have been used for detecting and characterizing interactions of large numbers of chemicals in combination. Single chemical dose-response data are used to predict an “additivity curve” along an environmentally relevant ray. A “mixture curve” is estimated fr...

  17. Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition

    NASA Astrophysics Data System (ADS)

    Bruder, H.; Raupach, R.; Sunnegardh, J.; Allmendinger, T.; Klotz, E.; Stierstorfer, K.; Flohr, T.

    2015-11-01

    In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples: in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high. In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR ‘source’ image data, while maintaining their resolution. It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J). We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR). Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover

  18. Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition.

    PubMed

    Bruder, H; Raupach, R; Sunnegardh, J; Allmendinger, T; Klotz, E; Stierstorfer, K; Flohr, T

    2015-11-07

    In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high.In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR 'source' image data, while maintaining their resolution.It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J). We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR). Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover spatial

  19. Statistical addition method for external noise sources affecting HF-MF-LF systems

    NASA Astrophysics Data System (ADS)

    Neudegg, David

    2001-01-01

    The current statistical method for the addition of external component noise sources in the LF, MF, and lower HF band (100 kHz to 3 MHz) produces total median noise levels that may be less than the largest-component median in some cases. Several case studies illustrate this anomaly. Methods used to sum the components rely on their power (decibels) distributions being represented as normal by the statistical parameters. The atmospheric noise component is not correctly represented by its decile values when it is assumed to have a normal distribution, causing anomalies in the noise summation when components are similar in magnitude. A revised component summation method is proposed, and the way it provides a more physically realistic total noise median for LF, MF, and lower HF frequencies is illustrated.

  20. Evaluation of proposed hardness assurance method for bipolar linear circuits with enhanced low dose rate sensitivity (ELDRS)

    SciTech Connect

    Pease, R.L.; Gehlhausen, M.; Krieg, J.; Titus, J.; Turflinger, T.; Emily, D.; Cohn, L.

    1998-12-01

    Data are presented on several low dose rate sensitive bipolar linear circuits to evaluate a proposed hardness assurance method. The circuits include primarily operational amplifiers and voltage comparators with a variety of sensitive components and failure modes. The proposed method, presented in 1997, includes an option between a low dose rate test at 10 mrd(Si)/s and room temperature and a 100 C elevated temperature irradiation test at a moderate dose rate. The results of this evaluation demonstrate that a 10 mrd(Si)/s test is able (in all but one case) to bound the worst case response within a factor of 2. For the moderate dose rate, 100 C test the worst case response is within a factor of 3 for 8 of 11 circuits, and for some circuits overpredicts the low dose rate response. The irradiation bias used for these tests often represents a more degrading bias condition than would be encountered in a typical space system application.

  1. Effect of the chlortetracycline addition method on methane production from the anaerobic digestion of swine wastewater.

    PubMed

    Huang, Lu; Wen, Xin; Wang, Yan; Zou, Yongde; Ma, Baohua; Liao, Xindi; Liang, Juanboo; Wu, Yinbao

    2014-10-01

    Effects of antibiotic residues on methane production in anaerobic digestion are commonly studied using the following two antibiotic addition methods: (1) adding manure from animals that consume a diet containing antibiotics, and (2) adding antibiotic-free animal manure spiked with antibiotics. This study used chlortetracycline (CTC) as a model antibiotic to examine the effects of the antibiotic addition method on methane production in anaerobic digestion under two different swine wastewater concentrations (0.55 and 0.22mg CTC/g dry manure). The results showed that CTC degradation rate in which manure was directly added at 0.55mg CTC/g (HSPIKE treatment) was lower than the control values and the rest of the treatment groups. Methane production from the HSPIKE treatment was reduced (p<0.05) by 12% during the whole experimental period and 15% during the first 7days. The treatments had no significant effect on the pH and chemical oxygen demand value of the digesters, and the total nitrogen of the 0.55mg CTC/kg manure collected from mediated swine was significantly higher than the other values. Therefore, different methane production under different antibiotic addition methods might be explained by the microbial activity and the concentrations of antibiotic intermediate products and metabolites. Because the primary entry route of veterinary antibiotics into an anaerobic digester is by contaminated animal manure, the most appropriate method for studying antibiotic residue effects on methane production may be using manure from animals that are given a particular antibiotic, rather than adding the antibiotic directly to the anaerobic digester.

  2. Compensation and additivity of anthropogenic mortality: life-history effects and review of methods.

    PubMed

    Péron, Guillaume

    2013-03-01

    Demographic compensation, the increase in average individual performance following a perturbation that reduces population size, and, its opposite, demographic overadditivity (or superadditivity) are central processes in both population ecology and wildlife management. A continuum of population responses to changes in cause-specific mortality exists, of which additivity and complete compensation constitute particular points. The position of a population on that continuum influences its ability to sustain exploitation and predation. Here I describe a method for quantifying where a population is on the continuum. Based on variance-covariance formulae, I describe a simple metric for the rate of compensation-additivity. I synthesize the results from 10 wildlife capture-recapture monitoring programmes from the literature and online databases, reviewing current statistical methods and the treatment of common sources of bias. These results are used to test hypotheses regarding the effects of life-history strategy, population density, average cause-specific mortality and age class on the rate of compensation-additivity. This comparative analysis highlights that long-lived species compensate less than short-lived species and that populations below their carrying capacity compensate less than those above.

  3. The methods of receiving coal water suspension and its use as the modifying additive in concrete

    NASA Astrophysics Data System (ADS)

    Buyantuyev, S. L.; Urkhanova, L. A.; Lkhasaranov, S. A.; Stebenkova, Y. Y.; Khmelev, A. B.; Kondratenko, A. S.

    2017-01-01

    Results of research of the coal water suspension (CWS) from a cake received in the electrodigit ways in the fluid environment and gas are given in article and also the possibilities of its use as the modifying additive in concrete are considered. Use of a coal cake is perspective as it is a withdrawal of the coal and concentrating enterprises and has extremely low cost. Methods of receiving CWS and possibility of formation of carbon nanomaterials (CNM) are given in their structure. Research and the analysis of a microstructure of a surface of exemplars before electrodigit processing, their element structure, dependence of durability of a cement stone on a look and quantity of an additive of CWS is conducted. For modification of cement the carbon nanomaterials received from the following exemplars of water coal suspensions were used: foams from a cake from a scrubber of the plasma modular reactor, coal water suspension from a cake from electrodigit installation. The product which can find further application for a power engineering as fuel for combustion, and also in structural materials science, in particular, as the modifying additive in concrete allows to receive these methods.

  4. Modified Maxium Likelihood Estimation Method for Completely Separated and Quasi-Completely Separated Data for a Dose-Response Model

    DTIC Science & Technology

    2015-08-01

    MODIFIED MAXIMUM LIKELIHOOD ESTIMATION METHOD FOR COMPLETELY SEPARATED AND QUASI-COMPLETELY SEPARATED DATA...Likelihood Estimation Method for Completely Separated and Quasi-Completely Separated Data for a Dose-Response Model 5a. CONTRACT NUMBER 5b. GRANT...quasi-completely separated , the traditional maximum likelihood estimation (MLE) method generates infinite estimates. The bias-reduction (BR) method

  5. The Wavelet Element Method. Part 2; Realization and Additional Features in 2D and 3D

    NASA Technical Reports Server (NTRS)

    Canuto, Claudio; Tabacco, Anita; Urban, Karsten

    1998-01-01

    The Wavelet Element Method (WEM) provides a construction of multiresolution systems and biorthogonal wavelets on fairly general domains. These are split into subdomains that are mapped to a single reference hypercube. Tensor products of scaling functions and wavelets defined on the unit interval are used on the reference domain. By introducing appropriate matching conditions across the interelement boundaries, a globally continuous biorthogonal wavelet basis on the general domain is obtained. This construction does not uniquely define the basis functions but rather leaves some freedom for fulfilling additional features. In this paper we detail the general construction principle of the WEM to the 1D, 2D and 3D cases. We address additional features such as symmetry, vanishing moments and minimal support of the wavelet functions in each particular dimension. The construction is illustrated by using biorthogonal spline wavelets on the interval.

  6. Standard addition method for laser ablation ICPMS using a spinning platform.

    PubMed

    Claverie, Fanny; Malherbe, Julien; Bier, Naomi; Molloy, John L; Long, Stephen E

    2013-04-02

    A method has been developed for the fast and easy determination of Pb, Sr, Ba, Ni, Cu, and Zn, which are of geological and environmental interest, in solid samples by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) using a spinning sample platform. The platform, containing a sample and a standard, is spun during the ablation, allowing the quasi-simultaneous ablation of both materials. The aerosols resulting from the ablation of sample and standard were mixed in the ablation cell allowing quantification of analytes by standard additions. The proportion of standard versus sample of the mixing can be increased by performing the ablation further from the axis of rotation. The ablated masses have been determined using a new strategy based on isotope dilution analysis. This spinning laser ablation method has been applied to the Allende meteorite and four powdered standard reference materials (SRMs) fused in lithium borate glasses: two sediments as well as a soil and a rock material. SRM 612 (Trace Elements in Glass) was also analyzed despite having a matrix slightly different from the glass standard obtained by lithium borate fusion. The deviation from the certified values was found to be less than 15% for most of the mass fractions for all the elements and samples studied, with an average precision of 10%. These results demonstrate the validity of the proposed method for the direct and fast analysis of solid samples of different matrixes by standard additions, using a single standard sample.

  7. Calculation algorithm for determination of dose versus LET using recombination method

    NASA Astrophysics Data System (ADS)

    Dobrzyńska, Magdalena

    2015-09-01

    Biological effectiveness of any type of radiation can be related to absorbed dose versus linear energy transfer (LET) associated with the particular radiation field. In complex radiation fields containing neutrons, especially in fields of high-energy particles or in stray radiation fields, radiation quality factor can be determined using detectors which response depends on LET. Recombination chambers, which are high-pressure, tissue equivalent ionization chambers operating under conditions of initial recombination of ions form a class of such detectors. Recombination Microdosimetric Method (RMM) is based on analysis of the shape of current-voltage characteristic (saturation curve) of recombination chamber. The ion collection process in the chamber is described by theoretical formula that contains a number of coefficients which depend on LET. The coefficients are calculated by fitting the shape of the theoretical curve to the experimental data. The purpose of the present project was to develop such a program for determination of radiation quality factor, basing on calculation of dose distribution versus LET using RMM.

  8. Effect of different oxytetracycline addition methods on its degradation behavior in soil.

    PubMed

    Chen, Gui-Xiu; He, Wei-Wei; Wang, Yan; Zou, Yong-De; Liang, Juan-Boo; Liao, Xin-Di; Wu, Yin-Bao

    2014-05-01

    The degradation behavior of veterinary antibiotics in soil is commonly studied using the following methods of adding antibiotics to the soil: (i) adding manure collected from animals fed with a diet containing antibiotics, (ii) adding antibiotic-free animal manure spiked with antibiotics and (iii) directly adding antibiotics. No research simultaneously comparing different antibiotic addition methods was found. Oxytetracycline (OTC) was used as a model antibiotic to compare the effect of the three commonly used antibiotic addition methods on OTC degradation behavior in soil. The three treatment methods have similar trends, though OTC degradation half-lives show the following significant differences (P<0.05): manure from swine fed OTC (treatment A)method to study the degradation and ecotoxicity of antibiotic residues in soil may be to use manure from animals that are given a particular antibiotic, rather than by adding it directly to the soil.

  9. A simplified method of four-dimensional dose accumulation using the mean patient density representation

    SciTech Connect

    Glide-Hurst, Carri K.; Hugo, Geoffrey D.; Liang Jian; Yan Di

    2008-12-15

    The purpose of this work was to demonstrate, both in phantom and patient, the feasibility of using an average 4DCT image set (AVG-CT) for 4D cumulative dose estimation. A series of 4DCT numerical phantoms and corresponding AVG-CTs were generated. For full 4D dose summation, static dose was calculated on each phase and cumulative dose was determined by combining each phase's static dose distribution with known tumor displacement. The AVG-CT cumulative dose was calculated similarly, although the same AVG-CT static dose distribution was used for all phases (i.e., tumor displacements). Four lung cancer cases were also evaluated for stereotactic body radiotherapy and conformal treatments; however, deformable image registration of the 4DCTs was used to generate the displacement vector fields (DVFs) describing patient-specific motion. Dose discrepancy between full 4D summation and AVG-CT approach was calculated and compared. For all phantoms, AVG-CT approximation yielded slightly higher cumulative doses compared to full 4D summation, with dose discrepancy increasing with increased tumor excursion. In vivo, using the AVG-CT coupled with deformable registration yielded clinically insignificant differences for all GTV parameters including the minimum, mean, maximum, dose to 99% of target, and dose to 1% of target. Furthermore, analysis of the spinal cord, esophagus, and heart revealed negligible differences in major dosimetric indices and dose coverage between the two dose calculation techniques. Simplifying 4D dose accumulation via the AVG-CT, while fully accounting for tumor deformation due to respiratory motion, has been validated, thereby, introducing the potential to streamline the use of 4D dose calculations in clinical practice, particularly for adaptive planning purposes.

  10. A fast numerical method for calculating the 3D proton dose profile in a single-ring wobbling spreading system.

    PubMed

    Riazi, Z; Afarideh, H; Sadighi-Bonabi, R

    2011-09-01

    Based on the determination of protons fluence at the phantom's surface, a 3D dose distribution is calculated inside a water phantom using a fast method. The dose contribution of secondary particles, originating from inelastic nuclear interactions, is also taken into account. This is achieved by assuming that 60% of the energy transferred to secondary particles is locally absorbed. Secondary radiation delivers approximately 16.8% of the total dose in the plateau region of the Bragg curve for monoenergetic protons of energy 190 MeV. The physical dose beyond the Bragg peak is obtained for a proton beam of 190 MeV using a Geant4 simulation. It is found that the dose beyond the Bragg peak is <0.02% of the maximum dose and is mainly delivered by protons produced via reactions of the secondary neutrons. The relative dose profile is also calculated by simulation of the proposed beam line in Geant4 code. The dose profile produced by our method agrees, within 2%, with the results predicted by the Fermi Eyges distribution function and the results of the Geant4 simulation. It is expected that the fast numerical approach proposed herein may be utilised in 3D deterministic treatment planning programs, to model proton propagation in order to analyse the effect of modifying the beam line.

  11. A simple method for the addition of rotenone in Arabidopsis thaliana leaves

    PubMed Central

    Maliandi, María V; Rius, Sebastián P; Busi, María V; Gomez-Casati, Diego F

    2015-01-01

    A simple and reproducible method for the treatment of Arabidopsis thaliana leaves with rotenone is presented. Rosette leaves were incubated with rotenone and Triton X-100 for at least 15 h. Treated leaves showed increased expression of COX19 and BCS1a, 2 genes known to be induced in Arabidopsis cell cultures after rotenone treatment. Moreover, rotenone/Triton X-100 incubated leaves presented an inhibition of oxygen uptake. The simplicity of the procedure shows this methodology is useful for studying the effect of the addition of rotenone to a photosynthetic tissue in situ. PMID:26357865

  12. A simple method for the addition of rotenone in Arabidopsis thaliana leaves.

    PubMed

    Maliandi, María V; Rius, Sebastián P; Busi, María V; Gomez-Casati, Diego F

    2015-01-01

    A simple and reproducible method for the treatment of Arabidopsis thaliana leaves with rotenone is presented. Rosette leaves were incubated with rotenone and Triton X-100 for at least 15 h. Treated leaves showed increased expression of COX19 and BCS1a, 2 genes known to be induced in Arabidopsis cell cultures after rotenone treatment. Moreover, rotenone/Triton X-100 incubated leaves presented an inhibition of oxygen uptake. The simplicity of the procedure shows this methodology is useful for studying the effect of the addition of rotenone to a photosynthetic tissue in situ.

  13. Systems and Methods for Fabricating Objects Including Amorphous Metal Using Techniques Akin to Additive Manufacturing

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas (Inventor)

    2017-01-01

    Systems and methods in accordance with embodiments of the invention fabricate objects including amorphous metals using techniques akin to additive manufacturing. In one embodiment, a method of fabricating an object that includes an amorphous metal includes: applying a first layer of molten metallic alloy to a surface; cooling the first layer of molten metallic alloy such that it solidifies and thereby forms a first layer including amorphous metal; subsequently applying at least one layer of molten metallic alloy onto a layer including amorphous metal; cooling each subsequently applied layer of molten metallic alloy such that it solidifies and thereby forms a layer including amorphous metal prior to the application of any adjacent layer of molten metallic alloy; where the aggregate of the solidified layers including amorphous metal forms a desired shape in the object to be fabricated; and removing at least the first layer including amorphous metal from the surface.

  14. Performance of the Tariff Method: validation of a simple additive algorithm for analysis of verbal autopsies

    PubMed Central

    2011-01-01

    Background Verbal autopsies provide valuable information for studying mortality patterns in populations that lack reliable vital registration data. Methods for transforming verbal autopsy results into meaningful information for health workers and policymakers, however, are often costly or complicated to use. We present a simple additive algorithm, the Tariff Method (termed Tariff), which can be used for assigning individual cause of death and for determining cause-specific mortality fractions (CSMFs) from verbal autopsy data. Methods Tariff calculates a score, or "tariff," for each cause, for each sign/symptom, across a pool of validated verbal autopsy data. The tariffs are summed for a given response pattern in a verbal autopsy, and this sum (score) provides the basis for predicting the cause of death in a dataset. We implemented this algorithm and evaluated the method's predictive ability, both in terms of chance-corrected concordance at the individual cause assignment level and in terms of CSMF accuracy at the population level. The analysis was conducted separately for adult, child, and neonatal verbal autopsies across 500 pairs of train-test validation verbal autopsy data. Results Tariff is capable of outperforming physician-certified verbal autopsy in most cases. In terms of chance-corrected concordance, the method achieves 44.5% in adults, 39% in children, and 23.9% in neonates. CSMF accuracy was 0.745 in adults, 0.709 in children, and 0.679 in neonates. Conclusions Verbal autopsies can be an efficient means of obtaining cause of death data, and Tariff provides an intuitive, reliable method for generating individual cause assignment and CSMFs. The method is transparent and flexible and can be readily implemented by users without training in statistics or computer science. PMID:21816107

  15. Addition of long-acting beta2-agonists to inhaled steroids versus higher dose inhaled steroids in adults and children with persistent asthma

    PubMed Central

    Ducharme, Francine M; Ni Chroinin, Muireann; Greenstone, Ilana; Lasserson, Toby J

    2014-01-01

    Background In asthmatic patients inadequately controlled on inhaled corticosteroids and/or those with moderate persistent asthma, two main options are recommended: the combination of a long-acting inhaled ß2 agonist (LABA) with inhaled corticosteroids (ICS) or use of a higher dose of inhaled corticosteroids. Objectives To determine the effect of the combination of long-acting ß2 agonists and inhaled corticosteroids compared to a higher dose of inhaled corticosteroids on the risk of asthma exacerbations, pulmonary function and on other measures of asthma control, and to look for characteristics associated with greater benefit for either treatment option. Search methods We identified randomised controlled trials (RCTs) through electronic database searches (MEDLINE, EMBASE and CINAHL), bibliographies of RCTs, clinical trial registries and correspondence with manufacturers until May 2008. Selection criteria RCTs that compared the combination of inhaled LABA and ICS to a higher dose of inhaled corticosteroids, in children and adults with asthma. Data collection and analysis Two authors independently assessed methodological quality and extracted data. We obtained confirmation from the trialists when possible. The primary endpoint was the number of patients experiencing one or more asthma exacerbations requiring oral corticosteroids. Main results This review included 48 studies (15,155 participants including 1155 children and 14,000 adults). Participants were inadequately controlled on their current ICS regimen, experiencing ongoing symptoms and with generally moderate (FEV1 60% to 79% of predicted) airway obstruction. The studies tested the combination of salmeterol or formoterol with a median dose of 400 mcg/day of beclomethasone or equivalent (BDP-eq) compared to a median of 1000 mcg/day of BDP-eq, usually for 24 weeks or less. There was a statistically significantly lower risk of exacerbations requiring systemic corticosteroids in patients treated with LABA and ICS

  16. Environmental dose assessment methods for normal operations at DOE nuclear sites

    SciTech Connect

    Strenge, D.L.; Kennedy, W.E. Jr.; Corley, J.P.

    1982-09-01

    Methods for assessing public exposure to radiation from normal operations at DOE facilities are reviewed in this report. The report includes a discussion of environmental doses to be calculated, a review of currently available environmental pathway models and a set of recommended models for use when environmental pathway modeling is necessary. Currently available models reviewed include those used by DOE contractors, the Environmental Protection Agency (EPA), the Nuclear Regulatory Commission (NRC), and other organizations involved in environmental assessments. General modeling areas considered for routine releases are atmospheric transport, airborne pathways, waterborne pathways, direct exposure to penetrating radiation, and internal dosimetry. The pathway models discussed in this report are applicable to long-term (annual) uniform releases to the environment: they do not apply to acute releases resulting from accidents or emergency situations.

  17. Influence of Al³⁺ addition on the flocculation and sedimentation of activated sludge: comparison of single and multiple dosing patterns.

    PubMed

    Wen, Yue; Zheng, Wanlin; Yang, Yundi; Cao, Asheng; Zhou, Qi

    2015-05-15

    In this study, the flocculation and sedimentation performance of activated sludge (AS) with single and multiple dosing of trivalent aluminum (Al(3+)) were studied. The AS samples were cultivated in sequencing batch reactors at 22 °C. The dosages of Al(3+) were 0.00, 0.125, 0.5, 1.0, and 1.5 meq/L for single dosing, and 0.1 meq/L for multiple dosing. Under single dosing conditions, as Al(3+) dosage increased, the zeta potential, total interaction energy, and effluent turbidity decreased, whereas the sludge volume index (SVI) increased, indicating that single Al(3+) dosing could enhance sludge flocculation, but deteriorate sedimentation. By comparison, adding an equal amount of Al(3+) through multiple dosing achieved a similar reduction in turbidity, but the zeta potential was higher, while the loosely bound extracellular polymeric substances (LB-EPS) content and SVI remarkably declined. Although the difference in the flocculation performances between the two dosing patterns was not significant, the underlying mechanisms were quite distinct: the interaction energy played a more important role under single dosing conditions, whereas multiple dosing was more effective in reducing the EPS content. Multiple dosing, which allows sufficient time for sludge restructuring and floc aggregation, could simultaneously optimize sludge flocculation and sedimentation.

  18. Determination of free acid by standard addition method in potassium thiocyanate

    SciTech Connect

    Baumann, E W

    1982-06-01

    The free acid content of solutions containing hydrolyzable ions has been determined potentiometrically by a standard addition method. Two increments of acid are added to the sample in 1M potassium thiocyanate solution. The sample concentration is calculated by solution of three simultaneous Nernst equations. The method has been demonstrated for solutions containing Al/sup 3 +/, Cr/sup 3 +/, Fe/sup 3 +/, Hg/sup 2 +/, Ni/sup 2 +/, Th/sup 4 +/, or UO/sub 2//sup 2 +/ with a metal-to-acid ratio of < 2.5. The method is suitable for determination of 10 ..mu..moles acid in 10 mL total volume. The accuracy can be judged from the agreement of the Nernst slopes found in the presence and absence of hydrolyzable ions. The relative standard deviation is < 2.5%. The report includes a survey of experiments with thermometric, pH, and Gran plot titrations in a variety of complexants, from which the method was evolved. Also included is a literature survey of sixty references, a discussion of the basic measurements, and a complete analytical procedure.

  19. Simple Method to Estimate Mean Heart Dose From Hodgkin Lymphoma Radiation Therapy According to Simulation X-Rays

    SciTech Connect

    Nimwegen, Frederika A. van; Cutter, David J.; Schaapveld, Michael; Rutten, Annemarieke; Kooijman, Karen; Krol, Augustinus D.G.; Janus, Cécile P.M.; Darby, Sarah C.; Leeuwen, Flora E. van; Aleman, Berthe M.P.

    2015-05-01

    Purpose: To describe a new method to estimate the mean heart dose for Hodgkin lymphoma patients treated several decades ago, using delineation of the heart on radiation therapy simulation X-rays. Mean heart dose is an important predictor for late cardiovascular complications after Hodgkin lymphoma (HL) treatment. For patients treated before the era of computed tomography (CT)-based radiotherapy planning, retrospective estimation of radiation dose to the heart can be labor intensive. Methods and Materials: Patients for whom cardiac radiation doses had previously been estimated by reconstruction of individual treatments on representative CT data sets were selected at random from a case–control study of 5-year Hodgkin lymphoma survivors (n=289). For 42 patients, cardiac contours were outlined on each patient's simulation X-ray by 4 different raters, and the mean heart dose was estimated as the percentage of the cardiac contour within the radiation field multiplied by the prescribed mediastinal dose and divided by a correction factor obtained by comparison with individual CT-based dosimetry. Results: According to the simulation X-ray method, the medians of the mean heart doses obtained from the cardiac contours outlined by the 4 raters were 30 Gy, 30 Gy, 31 Gy, and 31 Gy, respectively, following prescribed mediastinal doses of 25-42 Gy. The absolute-agreement intraclass correlation coefficient was 0.93 (95% confidence interval 0.85-0.97), indicating excellent agreement. Mean heart dose was 30.4 Gy with the simulation X-ray method, versus 30.2 Gy with the representative CT-based dosimetry, and the between-method absolute-agreement intraclass correlation coefficient was 0.87 (95% confidence interval 0.80-0.95), indicating good agreement between the two methods. Conclusion: Estimating mean heart dose from radiation therapy simulation X-rays is reproducible and fast, takes individual anatomy into account, and yields results comparable to the labor

  20. An identification method for enclosed voids restriction in manufacturability design for additive manufacturing structures

    NASA Astrophysics Data System (ADS)

    Liu, Shutian; Li, Quhao; Chen, Wenjiong; Tong, Liyong; Cheng, Gengdong

    2015-06-01

    Additive manufacturing (AM) technologies, such as selective laser sintering (SLS) and fused deposition modeling (FDM), have become the powerful tools for direct manufacturing of complex parts. This breakthrough in manufacturing technology makes the fabrication of new geometrical features and multiple materials possible. Past researches on designs and design methods often focused on how to obtain desired functional performance of the structures or parts, specific manufacturing capabilities as well as manufacturing constraints of AM were neglected. However, the inherent constraints in AM processes should be taken into account in design process. In this paper, the enclosed voids, one type of manufacturing constraints of AM, are investigated. In mathematics, enclosed voids restriction expressed as the solid structure is simplyconnected. We propose an equivalent description of simply-connected constraint for avoiding enclosed voids in structures, named as virtual temperature method (VTM). In this method, suppose that the voids in structure are filled with a virtual heating material with high heat conductivity and solid areas are filled with another virtual material with low heat conductivity. Once the enclosed voids exist in structure, the maximum temperature value of structure will be very high. Based upon this method, the simplyconnected constraint is equivalent to maximum temperature constraint. And this method can be easily used to formulate the simply-connected constraint in topology optimization. The effectiveness of this description method is illustrated by several examples. Based upon topology optimization, an example of 3D cantilever beam is used to illustrate the trade-off between manufacturability and functionality. Moreover, the three optimized structures are fabricated by FDM technology to indicate further the necessity of considering the simply-connected constraint in design phase for AM.

  1. Growth enhancement of Picea abies trees under long-term, low-dose N addition is due to morphological more than to physiological changes.

    PubMed

    Krause, Kim; Cherubini, Paolo; Bugmann, Harald; Schleppi, Patrick

    2012-12-01

    Human activities have drastically increased nitrogen (N) inputs into natural and near-natural terrestrial ecosystems such that critical loads are now being exceeded in many regions of the world. This implies that these ecosystems are shifting from natural N limitation to eutrophication or even N saturation. This process is expected to modify the growth of forests and thus, along with management, to affect their carbon (C) sequestration. However, knowledge of the physiological mechanisms underlying tree response to N inputs, especially in the long term, is still lacking. In this study, we used tree-ring patterns and a dual stable isotope approach (δ(13)C and δ(18)O) to investigate tree growth responses and the underlying physiological reactions in a long-term, low-dose N addition experiment (+23 kg N ha(-1) a(-1)). This experiment has been conducted for 14 years in a mountain Picea abies (L.) Karst. forest in Alptal, Switzerland, using a paired-catchment design. Tree stem C sequestration increased by ∼22%, with an N use efficiency (NUE) of ca. 8 kg additional C in tree stems per kg of N added. Neither earlywood nor latewood δ(13)C values changed significantly compared with the control, indicating that the intrinsic water use efficiency (WUE(i)) (A/g(s)) did not change due to N addition. Further, the isotopic signal of δ(18)O in early- and latewood showed no significant response to the treatment, indicating that neither stomatal conductance nor leaf-level photosynthesis changed significantly. Foliar analyses showed that needle N concentration significantly increased in the fourth to seventh treatment year, accompanied by increased dry mass and area per needle, and by increased tree height growth. Later, N concentration and height growth returned to nearly background values, while dry mass and area per needle remained high. Our results support the hypothesis that enhanced stem growth caused by N addition is mainly due to an increased leaf area index (LAI

  2. Determination of free acid by standard addition method in potassium thiocyanate

    SciTech Connect

    Not Available

    1981-06-01

    An analytical method for determination of free acidity in all SRP process solutions has been developed. Free acidity was successfully determined in solutions of nitric acid and the nitrates of aluminum, chromium(III), iron(III), mercury(II), nickel(II), thorium, and uranium(VI), at metal-to-acid ratios <2.5. Sample requirements, instrumentation, and mode of operation are similar to those currently used in the Laboratories Department free acid procedures. The simple procedure would be suitable for automation and microprocessor control. The method consists of two additions of known increments of acid into a solution containing the sample aliquot (10 ..mu..moles free acid) and 10 mL 1M potassium thiocyanate. The potential is determined in the initial solution and after each addition with a glass electrode and pH meter. The sample concentration is calculated by solution of three simultaneous Nernst equations. Two programs for this iterative computation are available: one written for the PDP-15 computer and another for a Hewlett-Packard 67 (or 97) programmable calculator. The accuracy of the result is verified by a slope that approximates the theoretical Nernst value. The relative standard deviation is <2.5%. This memorandum includes a survey of experiments with thermometric, pH, and Gran plot titrations in a variety of complexants, from which this particular system and technique logically evolved. The appendix includes a literature survey of sixty references, a discussion of the basic measurements, and a complete analytical procedure. The final step for completion of this RTA is training and consultation at the convenience of the Laboratories Department for demonstration of the method with process samples.

  3. A Novel Method to Incorporate the Spatial Location of the Lung Dose Distribution into Predictive Radiation Pneumonitis Modeling

    SciTech Connect

    Vinogradskiy, Yevgeniy; Tucker, Susan L.; Liao, Zhongxing; Martel, Mary K.

    2012-03-15

    Purpose: Studies have proposed that patients who receive radiation therapy to the base of the lung are more susceptible to radiation pneumonitis than patients who receive therapy to the apex of the lung. The primary purpose of the present study was to develop a novel method to incorporate the lung dose spatial information into a predictive radiation pneumonitis model. A secondary goal was to apply the method to a 547 lung cancer patient database to determine whether including the spatial information could improve the fit of our model. Methods and Materials: The three-dimensional dose distribution of each patient was mapped onto one common coordinate system. The boundaries of the coordinate system were defined by the extreme points of each individual patient lung. Once all dose distributions were mapped onto the common coordinate system, the spatial information was incorporated into a Lyman-Kutcher-Burman predictive radiation pneumonitis model. Specifically, the lung dose voxels were weighted using a user-defined spatial weighting matrix. We investigated spatial weighting matrices that linearly scaled each dose voxel according to the following orientations: superior-inferior, anterior-posterior, medial-lateral, left-right, and radial. The model parameters were fit to our patient cohort with the endpoint of severe radiation pneumonitis. The spatial dose model was compared against a conventional dose-volume model to determine whether adding a spatial component improved the fit of the model. Results: Of the 547 patients analyzed, 111 (20.3%) experienced severe radiation pneumonitis. Adding in a spatial parameter did not significantly increase the accuracy of the model for any of the weighting schemes. Conclusions: A novel method was developed to investigate the relationship between the location of the deposited lung dose and pneumonitis rate. The method was applied to a patient database, and we found that for our patient cohort, the spatial location does not influence

  4. Phase II dose-response trials: A simulation study to compare analysis method performance under design considerations.

    PubMed

    Rekowski, Jan; Köllmann, Claudia; Bornkamp, Björn; Ickstadt, Katja; Scherag, André

    2017-02-21

    Phase II trials are intended to provide information about the dose-response relationship and to support the choice of doses for a pivotal phase III trial. Recently, new analysis methods have been proposed to address these objectives, and guidance is needed to select the most appropriate analysis method in specific situations. We set up a simulation study to evaluate multiple performance measures of one traditional and three more recent dose-finding approaches under four design options and illustrate the investigated analysis methods with an example from clinical practice. Our results reveal no general recommendation for a particular analysis method across all design options and performance measures. However, we also demonstrate that the new analysis methods are worth the effort compared to the traditional ANOVA-based approach.

  5. A novel method for interactive multi-objective dose-guided patient positioning

    NASA Astrophysics Data System (ADS)

    Haehnle, Jonas; Süss, Philipp; Landry, Guillaume; Teichert, Katrin; Hille, Lucas; Hofmaier, Jan; Nowak, Dimitri; Kamp, Florian; Reiner, Michael; Thieke, Christian; Ganswindt, Ute; Belka, Claus; Parodi, Katia; Küfer, Karl-Heinz; Kurz, Christopher

    2017-01-01

    In intensity-modulated radiation therapy (IMRT), 3D in-room imaging data is typically utilized for accurate patient alignment on the basis of anatomical landmarks. In the presence of non-rigid anatomical changes, it is often not obvious which patient position is most suitable. Thus, dose-guided patient alignment is an interesting approach to use available in-room imaging data for up-to-date dose calculation, aimed at finding the position that yields the optimal dose distribution. This contribution presents the first implementation of dose-guided patient alignment as multi-criteria optimization problem. User-defined clinical objectives are employed for setting up a multi-objective problem. Using pre-calculated dose distributions at a limited number of patient shifts and dose interpolation, a continuous space of Pareto-efficient patient shifts becomes accessible. Pareto sliders facilitate interactive browsing of the possible shifts with real-time dose display to the user. Dose interpolation accuracy is validated and the potential of multi-objective dose-guided positioning demonstrated for three head and neck (H&N) and three prostate cancer patients. Dose-guided positioning is compared to replanning for all cases. A delineated replanning CT served as surrogate for in-room imaging data. Dose interpolation accuracy was high. Using a 2 % dose difference criterion, a median pass-rate of 95.7% for H&N and 99.6% for prostate cases was determined in a comparison to exact dose calculations. For all patients, dose-guided positioning allowed to find a clinically preferable dose distribution compared to bony anatomy based alignment. For all H&N cases, mean dose to the spared parotid glands was below 26~\\text{Gy} (up to 27.5~\\text{Gy} with bony alignment) and clinical target volume (CTV) {{V}95 % } above 99.1% (compared to 95.1%). For all prostate patients, CTV {{V}95 % } was above 98.9% (compared to 88.5%) and {{V}50~\\text{Gy}} to the rectum below 50 % (compared to 56

  6. Evaluation of HIFU-induced lesion region using temperature threshold and equivalent thermal dose methods

    NASA Astrophysics Data System (ADS)

    Chang, Shihui; Xue, Fanfan; Zhou, Wenzheng; Zhang, Ji; Jian, Xiqi

    2017-03-01

    Usually, numerical simulation is used to predict the acoustic filed and temperature distribution of high intensity focused ultrasound (HIFU). In this paper, the simulated lesion volumes obtained by temperature threshold (TRT) 60 °C and equivalent thermal dose (ETD) 240 min were compared with the experimental results which were obtained by animal tissue experiment in vitro. In the simulation, the calculated model was established according to the vitro tissue experiment, and the Finite Difference Time Domain (FDTD) method was used to calculate the acoustic field and temperature distribution in bovine liver by the Westervelt formula and Pennes bio-heat transfer equation, and the non-linear characteristics of the ultrasound was considered. In the experiment, the fresh bovine liver was exposed for 8s, 10s, 12s under different power conditions (150W, 170W, 190W, 210W), and the exposure was repeated 6 times under the same dose. After the exposures, the liver was sliced and photographed every 0.2mm, and the area of the lesion region in every photo was calculated. Then, every value of the areas was multiplied by 0.2mm, and summed to get the approximation volume of the lesion region. The comparison result shows that the lesion volume of the region calculated by TRT 60 °C in simulation was much closer to the lesion volume obtained in experiment, and the volume of the region above 60 °C was larger than the experimental results, but the volume deviation was not exceed 10%. The volume of the lesion region calculated by ETD 240 min was larger than that calculated by TRT 60 °C in simulation, and the volume deviations were ranged from 4.9% to 23.7%.

  7. AAPM recommendations on dose prescription and reporting methods for permanent interstitial brachytherapy for prostate cancer: Report of Task Group 137

    SciTech Connect

    Nath, Ravinder; Bice, William S.; Butler, Wayne M.; Chen Zhe; Meigooni, Ali S.; Narayana, Vrinda; Rivard, Mark J.; Yu Yan

    2009-11-15

    tumor cure probability models, are reviewed. Based on these developments in literature, the AAPM recommends guidelines for dose prescription from a physics perspective for routine patient treatment, clinical trials, and for treatment planning software developers. The authors continue to follow the current recommendations on using D{sub 90} and V{sub 100} as the primary quantities, with more specific guidelines on the use of the imaging modalities and the timing of the imaging. The AAPM recommends that the postimplant evaluation should be performed at the optimum time for specific radionuclides. In addition, they encourage the use of a radiobiological model with a specific set of parameters to facilitate relative comparisons of treatment plans reported by different institutions using different loading patterns or radionuclides.

  8. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation

    NASA Technical Reports Server (NTRS)

    Van Dongen, Hans P A.; Maislin, Greg; Mullington, Janet M.; Dinges, David F.

    2003-01-01

    OBJECTIVES: To inform the debate over whether human sleep can be chronically reduced without consequences, we conducted a dose-response chronic sleep restriction experiment in which waking neurobehavioral and sleep physiological functions were monitored and compared to those for total sleep deprivation. DESIGN: The chronic sleep restriction experiment involved randomization to one of three sleep doses (4 h, 6 h, or 8 h time in bed per night), which were maintained for 14 consecutive days. The total sleep deprivation experiment involved 3 nights without sleep (0 h time in bed). Each study also involved 3 baseline (pre-deprivation) days and 3 recovery days. SETTING: Both experiments were conducted under standardized laboratory conditions with continuous behavioral, physiological and medical monitoring. PARTICIPANTS: A total of n = 48 healthy adults (ages 21-38) participated in the experiments. INTERVENTIONS: Noctumal sleep periods were restricted to 8 h, 6 h or 4 h per day for 14 days, or to 0 h for 3 days. All other sleep was prohibited. RESULTS: Chronic restriction of sleep periods to 4 h or 6 h per night over 14 consecutive days resulted in significant cumulative, dose-dependent deficits in cognitive performance on all tasks. Subjective sleepiness ratings showed an acute response to sleep restriction but only small further increases on subsequent days, and did not significantly differentiate the 6 h and 4 h conditions. Polysomnographic variables and delta power in the non-REM sleep EEG-a putative marker of sleep homeostasis--displayed an acute response to sleep restriction with negligible further changes across the 14 restricted nights. Comparison of chronic sleep restriction to total sleep deprivation showed that the latter resulted in disproportionately large waking neurobehavioral and sleep delta power responses relative to how much sleep was lost. A statistical model revealed that, regardless of the mode of sleep deprivation, lapses in behavioral alertness

  9. Statistical methods for a three-period crossover design in which high dose cannot be used first.

    PubMed

    Peace, K E; Koch, G G

    1993-03-01

    Design and analysis methods for the three-period crossover trial defined by the sequences: (D0, D1, D2), (D1, D0, D2), and (D1, D2, D0), where D0 is a placebo, and D1 and D2 are a low dose and a high dose of a drug, respectively, are developed. This design may be used when investigators are unwilling to administer a higher dose of a new drug to a patient before administering a lower dose. In using this design, patients should be randomized to sequences in blocks that are integer multiples of 3. Both parametric and non-parametric analysis methods are based on contrasts that capture intrapatient variability only and provide unbiased estimates and hypothesis tests of pairwise differences between carryover, direct dose, and period effects. The design and methods are illustrated with data reflecting the cognitive component of the Alzheimer's disease assessment scale collected in a large clinical trial of Tacrine at doses of 0, 40, and 80 mg/day.

  10. A first approach to evaluate the cell dose in highly porous scaffolds by using a nondestructive metabolic method

    PubMed Central

    Divieto, Carla; Sassi, Maria Paola

    2015-01-01

    Background: In cell-based therapies, in vitro studies on biomimetic cell–scaffold constructs can facilitate the determination of the cell dose, a key factor in guaranteeing the effectiveness of the treatment. However, highly porous scaffolds do not allow a nondestructive evaluation of the cell number. Our objective was to develop a nondestructive method for human mesenchymal stem cells dose evaluation in a highly porous scaffold for bone regeneration. Materials & measurement method: Proliferation trend of human mesenchymal stem cells on Biocoral® scaffolds was measured by a resazurin-based assay here optimized for 3D cultures. The method allows to noninvasively follow the cell proliferation on biocorals over 3 weeks with very high reproducibility. Conclusion: This reliable method could be a powerful tool in cell-based therapies for cell dose determination. PMID:28031911

  11. Simulation of Powder Layer Deposition in Additive Manufacturing Processes Using the Discrete Element Method

    SciTech Connect

    Herbold, E. B.; Walton, O.; Homel, M. A.

    2015-10-26

    This document serves as a final report to a small effort where several improvements were added to a LLNL code GEODYN-­L to develop Discrete Element Method (DEM) algorithms coupled to Lagrangian Finite Element (FE) solvers to investigate powder-­bed formation problems for additive manufacturing. The results from these simulations will be assessed for inclusion as the initial conditions for Direct Metal Laser Sintering (DMLS) simulations performed with ALE3D. The algorithms were written and performed on parallel computing platforms at LLNL. The total funding level was 3-­4 weeks of an FTE split amongst two staff scientists and one post-­doc. The DEM simulations emulated, as much as was feasible, the physical process of depositing a new layer of powder over a bed of existing powder. The DEM simulations utilized truncated size distributions spanning realistic size ranges with a size distribution profile consistent with realistic sample set. A minimum simulation sample size on the order of 40-­particles square by 10-­particles deep was utilized in these scoping studies in order to evaluate the potential effects of size segregation variation with distance displaced in front of a screed blade. A reasonable method for evaluating the problem was developed and validated. Several simulations were performed to show the viability of the approach. Future investigations will focus on running various simulations investigating powder particle sizing and screen geometries.

  12. Determination of robotic trajectory best distance using simple additive weighting method

    NASA Astrophysics Data System (ADS)

    Rohman, Muchamad Zainul

    2017-02-01

    Determination of the best distance, namely the closest distance and in the shortest time to reach a destination appropriately, has been applied in daily life. The determination of the best distance can be applied on robot trajectory so that robot can reach its destination quickly and appropriately without taking much time in robot contest, such as Indonesian Smart Robot Contest (KRCI). The difficulties to determine the closest distance occur due to the existing trajectory alternatives. In this aspect the reliability of a robot is tested and contested. Every year there are many robot contests either local, national, or international scale. Robot trajectory is a place or points passed by moving objects. This study used Simple Additive Method (SAW) method to find the closest distance by finding the value of alternative tracks existing on the trajectory. Determination of the closest distance on robot trajectory gives facility for the users to find the closest distance of a robot trajectory so as to input the correct algorithm in robot to reach the destination quickly and appropriately.

  13. Determination of surface dose rate of indigenous (32)P patch brachytherapy source by experimental and Monte Carlo methods.

    PubMed

    Kumar, Sudhir; Srinivasan, P; Sharma, S D; Saxena, Sanjay Kumar; Bakshi, A K; Dash, Ashutosh; Babu, D A R; Sharma, D N

    2015-09-01

    Isotope production and Application Division of Bhabha Atomic Research Center developed (32)P patch sources for treatment of superficial tumors. Surface dose rate of a newly developed (32)P patch source of nominal diameter 25 mm was measured experimentally using standard extrapolation ionization chamber and Gafchromic EBT film. Monte Carlo model of the (32)P patch source along with the extrapolation chamber was also developed to estimate the surface dose rates from these sources. The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and radiochromic films are 82.03±4.18 (k=2) and 79.13±2.53 (k=2) respectively. The two values of the surface dose rates measured using the two independent experimental methods are in good agreement to each other within a variation of 3.5%. The surface dose rate to tissue (cGy/min) estimated using the MCNP Monte Carlo code works out to be 77.78±1.16 (k=2). The maximum deviation between the surface dose rates to tissue obtained by Monte Carlo and the extrapolation chamber method is 5.2% whereas the difference between the surface dose rates obtained by radiochromic film measurement and the Monte Carlo simulation is 1.7%. The three values of the surface dose rates of the (32)P patch source obtained by three independent methods are in good agreement to one another within the uncertainties associated with their measurements and calculation. This work has demonstrated that MCNP based electron transport simulations are accurate enough for determining the dosimetry parameters of the indigenously developed (32)P patch sources for contact brachytherapy applications.

  14. Multiple Linkage Disequilibrium Mapping Methods to Validate Additive Quantitative Trait Loci in Korean Native Cattle (Hanwoo)

    PubMed Central

    Li, Yi; Kim, Jong-Joo

    2015-01-01

    The efficiency of genome-wide association analysis (GWAS) depends on power of detection for quantitative trait loci (QTL) and precision for QTL mapping. In this study, three different strategies for GWAS were applied to detect QTL for carcass quality traits in the Korean cattle, Hanwoo; a linkage disequilibrium single locus regression method (LDRM), a combined linkage and linkage disequilibrium analysis (LDLA) and a BayesCπ approach. The phenotypes of 486 steers were collected for weaning weight (WWT), yearling weight (YWT), carcass weight (CWT), backfat thickness (BFT), longissimus dorsi muscle area, and marbling score (Marb). Also the genotype data for the steers and their sires were scored with the Illumina bovine 50K single nucleotide polymorphism (SNP) chips. For the two former GWAS methods, threshold values were set at false discovery rate <0.01 on a chromosome-wide level, while a cut-off threshold value was set in the latter model, such that the top five windows, each of which comprised 10 adjacent SNPs, were chosen with significant variation for the phenotype. Four major additive QTL from these three methods had high concordance found in 64.1 to 64.9Mb for Bos taurus autosome (BTA) 7 for WWT, 24.3 to 25.4Mb for BTA14 for CWT, 0.5 to 1.5Mb for BTA6 for BFT and 26.3 to 33.4Mb for BTA29 for BFT. Several candidate genes (i.e. glutamate receptor, ionotropic, ampa 1 [GRIA1], family with sequence similarity 110, member B [FAM110B], and thymocyte selection-associated high mobility group box [TOX]) may be identified close to these QTL. Our result suggests that the use of different linkage disequilibrium mapping approaches can provide more reliable chromosome regions to further pinpoint DNA makers or causative genes in these regions. PMID:26104396

  15. Multiple Linkage Disequilibrium Mapping Methods to Validate Additive Quantitative Trait Loci in Korean Native Cattle (Hanwoo).

    PubMed

    Li, Yi; Kim, Jong-Joo

    2015-07-01

    The efficiency of genome-wide association analysis (GWAS) depends on power of detection for quantitative trait loci (QTL) and precision for QTL mapping. In this study, three different strategies for GWAS were applied to detect QTL for carcass quality traits in the Korean cattle, Hanwoo; a linkage disequilibrium single locus regression method (LDRM), a combined linkage and linkage disequilibrium analysis (LDLA) and a BayesCπ approach. The phenotypes of 486 steers were collected for weaning weight (WWT), yearling weight (YWT), carcass weight (CWT), backfat thickness (BFT), longissimus dorsi muscle area, and marbling score (Marb). Also the genotype data for the steers and their sires were scored with the Illumina bovine 50K single nucleotide polymorphism (SNP) chips. For the two former GWAS methods, threshold values were set at false discovery rate <0.01 on a chromosome-wide level, while a cut-off threshold value was set in the latter model, such that the top five windows, each of which comprised 10 adjacent SNPs, were chosen with significant variation for the phenotype. Four major additive QTL from these three methods had high concordance found in 64.1 to 64.9Mb for Bos taurus autosome (BTA) 7 for WWT, 24.3 to 25.4Mb for BTA14 for CWT, 0.5 to 1.5Mb for BTA6 for BFT and 26.3 to 33.4Mb for BTA29 for BFT. Several candidate genes (i.e. glutamate receptor, ionotropic, ampa 1 [GRIA1], family with sequence similarity 110, member B [FAM110B], and thymocyte selection-associated high mobility group box [TOX]) may be identified close to these QTL. Our result suggests that the use of different linkage disequilibrium mapping approaches can provide more reliable chromosome regions to further pinpoint DNA makers or causative genes in these regions.

  16. Neutrophil recruitment and phagocytosis of boar spermatozoa after artificial insemination of sows, and the effects of inseminate volume, sperm dose and specific additives in the extender.

    PubMed

    Matthijs, A; Engel, B; Woelders, H

    2003-03-01

    In this study the recruitment of leucocytes and phagocytosis of spermatozoa after artificial insemination of multiparous sows was investigated. In Expt 1, groups of sows received either no inseminate (n = 6) or inseminates with various concentrations of spermatozoa and seminal plasma or different inseminate volumes (n = 9 per group). In Expt 2, groups of sows received inseminates containing no addition, caffeine + CaCl(2), or excess EDTA (n = 6 per group). Leucocytes and spermatozoa were counted in the collected backflow from the vulva, and in the PBS flushings of the genital tract of sows killed at 4 h after insemination. Tissue homogenates were checked for remaining spermatozoa. Leucocyte recruitment did not depend on the presence of seminal plasma or spermatozoa. In the control groups about 43% of the inseminated spermatozoa were found in the backflow and 5% in the genital tract. Many spermatozoa could be recognized inside polymorphonuclear leucocytes. With an inseminate volume of 20 ml instead of 80 ml, fewer spermatozoa were found in the backflow and more (non-phagocytosed) spermatozoa were recovered in the uterus (P < or = 0.05). With a sperm dose of 0.24 x 10(9) instead of 2.4 x 10(9), a higher percentage of the inseminated spermatozoa was recovered in the oviducts (P < or = 0.05). The use of caffeine + CaCl(2) resulted in lower recruitment of leucocytes (P < or = 0.05) and a higher number of non-phagocytosed spermatozoa in the uterus (P < or = 0.01) compared with controls. The numbers of spermatozoa in the oviducts were not different. Insemination with excess EDTA had no positive effects on the number of spermatozoa in the genital tract.

  17. An efficient enantioselective method for asymmetric Michael addition of nitroalkanes to alpha,beta-unsaturated aldehydes.

    PubMed

    Wang, Yongcan; Li, Pengfei; Liang, Xinmiao; Zhang, Tony Y; Ye, Jinxing

    2008-03-14

    The addition of nitroalkanes to alpha,beta-unsaturated aldehydes under the catalysis of (S)-2-(diphenyl(trimethylsilyloxy)methyl)pyrrolidine and lithium acetate as additive afforded gamma-nitroaldehydes in good yield and up to 97% ee.

  18. A new method to evaluate plume characteristics of hydrofluoroalkane and chlorofluorocarbon metered dose inhalers.

    PubMed

    Gabrio, B J; Stein, S W; Velasquez, D J

    1999-09-10

    Two concerns raised when comparing metered dose inhalers (MDIs) to other inhalation devices are their relatively high throat deposition and the 'cold-Freon' effect seen in a small number of patients. The cold-Freon effect is presumed to be a result of the cold, forceful MDI plume impacting on the back of a patient's throat. This in vitro study uses a new plume characterization method to determine the spray force and plume temperature of various MDIs. Spray force measurements were made for 28 marketed products consisting of bronchodilators, steroids, press-and-breathe, breath-actuated and nasal inhalers. Results show that chlorofluorocarbon (CFC)-containing MDIs produce extremely forceful and cold plumes. Several hydrofluoralkane (HFA)-containing MDIs produced much softer and warmer plumes, but two HFA products had spray forces similar to the CFC products. Although the type of propellant used can affect spray force, actuator orifice diameter is the most important factor. Data obtained from marketed products and experimental inhalers show that MDIs that have a low spray force also have low throat deposition.

  19. Numerical Method for the Design of Healing Chamber in Additive-Manufactured Dental Implants.

    PubMed

    Lee, Hsiao-Chien; Tsai, Pei-I; Huang, Chih-Chieh; Chen, San-Yuan; Chao, Chuen-Guang; Tsou, Nien-Ti

    2017-01-01

    The inclusion of a healing chamber in dental implants has been shown to promote biological healing. In this paper, a novel numerical approach to the design of the healing chamber for additive-manufactured dental implants is proposed. This study developed an algorithm for the modeling of bone growth and employed finite element method in ANSYS to facilitate the design of healing chambers with a highly complex configuration. The model was then applied to the design of dental implants for insertion into the posterior maxillary bones. Two types of ITI® solid cylindrical screwed implant with extra rectangular-shaped healing chamber as an initial design are adopted, with which to evaluate the proposed system. This resulted in several configurations for the healing chamber, which were then evaluated based on the corresponding volume fraction of healthy surrounding bone. The best of these implants resulted in a healing chamber surrounded by around 9.2% more healthy bone than that obtained from the original design. The optimal design increased the contact area between the bone and implant by around 52.9%, which is expected to have a significant effect on osseointegration. The proposed approach is highly efficient which typically completes the optimization of each implant within 3-5 days on an ordinary personal computer. It is also sufficiently general to permit extension to various loading conditions.

  20. Numerical Method for the Design of Healing Chamber in Additive-Manufactured Dental Implants

    PubMed Central

    Lee, Hsiao-Chien; Tsai, Pei-I; Huang, Chih-Chieh; Chen, San-Yuan; Chao, Chuen-Guang

    2017-01-01

    The inclusion of a healing chamber in dental implants has been shown to promote biological healing. In this paper, a novel numerical approach to the design of the healing chamber for additive-manufactured dental implants is proposed. This study developed an algorithm for the modeling of bone growth and employed finite element method in ANSYS to facilitate the design of healing chambers with a highly complex configuration. The model was then applied to the design of dental implants for insertion into the posterior maxillary bones. Two types of ITI® solid cylindrical screwed implant with extra rectangular-shaped healing chamber as an initial design are adopted, with which to evaluate the proposed system. This resulted in several configurations for the healing chamber, which were then evaluated based on the corresponding volume fraction of healthy surrounding bone. The best of these implants resulted in a healing chamber surrounded by around 9.2% more healthy bone than that obtained from the original design. The optimal design increased the contact area between the bone and implant by around 52.9%, which is expected to have a significant effect on osseointegration. The proposed approach is highly efficient which typically completes the optimization of each implant within 3–5 days on an ordinary personal computer. It is also sufficiently general to permit extension to various loading conditions. PMID:28293628

  1. Nonlinearity measurements of solar cells with an LED-based combinatorial flux addition method

    PubMed Central

    Hamadani, Behrang H.; Shore, Andrew; Roller, John; Yoon, Howard W; Campanelli, Mark

    2016-01-01

    We present a light emitting diode (LED)-based system utilizing a combinatorial flux addition method to investigate the nonlinear relationship in solar cells between the output current of the cell and the incident irradiance level. The magnitude of the light flux is controlled by the supplied currents to two LEDs (or two sets of them) in a combinatorial fashion. The signals measured from the cell are arranged within a related overdetermined linear system of equations derived from an appropriately chosen Nth degree polynomial representing the relationship between the measured signals and the incident fluxes. The flux values and the polynomial coefficients are then solved for by linear least squares to obtain the best fit. The technique can be applied to any solar cell, under either monochromatic or broadband spectrum. For the unscaled solution, no reference detectors or prior calibrations of the light flux are required. However, if at least one calibrated irradiance value is known, then the entire curve can be scaled to an appropriate spectral responsivity value. Using this technique, a large number of data points can be obtained in a relatively short time scale over a large signal range. PMID:27524837

  2. Nonlinearity measurements of solar cells with an LED-based combinatorial flux addition method.

    PubMed

    Hamadani, Behrang H; Shore, Andrew; Roller, John; Yoon, Howard W; Campanelli, Mark

    2016-02-01

    We present a light emitting diode (LED)-based system utilizing a combinatorial flux addition method to investigate the nonlinear relationship in solar cells between the output current of the cell and the incident irradiance level. The magnitude of the light flux is controlled by the supplied currents to two LEDs (or two sets of them) in a combinatorial fashion. The signals measured from the cell are arranged within a related overdetermined linear system of equations derived from an appropriately chosen N(th) degree polynomial representing the relationship between the measured signals and the incident fluxes. The flux values and the polynomial coefficients are then solved for by linear least squares to obtain the best fit. The technique can be applied to any solar cell, under either monochromatic or broadband spectrum. For the unscaled solution, no reference detectors or prior calibrations of the light flux are required. However, if at least one calibrated irradiance value is known, then the entire curve can be scaled to an appropriate spectral responsivity value. Using this technique, a large number of data points can be obtained in a relatively short time scale over a large signal range.

  3. Stable solidification of cesium with an allophane additive by a pressing/sintering method

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxia; Wu, Yan; Wei, Yuezhou; Mimura, Hitoshi; Matsukura, Minoru

    2017-03-01

    Pyrolysis of AMP/SiO2 adsorbed Cs (AMP-Cs/SiO2) occurred at > 400 °C sintering temperature, and Cs immobilisation decreased from 100% to 40% after sintering at 1200 °C. To safely dispose radioactive Cs, allophane was immobilized with AMP-Cs/SiO2 to prepare a stable form by using a pressing/sintering method. The structure of AMP-Cs/SiO2 collapsed, and cesium aluminosilicate formed more easily under conditions of higher sintering temperature (>800 °C) or increasing mixing ratio of allophane (mass ratio = 1:3 AMP-Cs/SiO2-allophane). The decomposition products of AMP-Cs/SiO2 were Cs2O, MoO3 and P2O5 at 1200 °C. Cs2O volatilisation was depressed by allophane addition, and a stable immobilisation phase of Cs4Al4Si20O48 formed. An immobilisation ratio of Cs of approximately 100% was maintained. The leachability of Cs for AMP-Cs/SiO2-allophane (1:3, 1200 °C) in distilled water at 25 °C and 90 °C for 15 days was estimated as 0.174% and 1.55%, respectively.

  4. DETECTORS AND EXPERIMENTAL METHODS: ELDRS and dose-rate dependence of vertical NPN transistor

    NASA Astrophysics Data System (ADS)

    Zheng, Yu-Zhan; Lu, Wu; Ren, Di-Yuan; Wang, Gai-Li; Yu, Xue-Feng; Guo, Qi

    2009-01-01

    The enhanced low-dose-rate sensitivity (ELDRS) and dose-rate dependence of vertical NPN transistors are investigated in this article. The results show that the vertical NPN transistors exhibit more degradation at low dose rate, and that this degradation is attributed to the increase on base current. The oxide trapped positive charge near the SiO2-Si interface and interface traps at the interface can contribute to the increase on base current and the two-stage hydrogen mechanism associated with space charge effect can well explain the experimental results.

  5. A method for independent modelling in support of regulatory review of dose assessments.

    PubMed

    Dverstorp, Björn; Xu, Shulan

    2017-03-22

    Several countries consider geological disposal facilities as the preferred option for spent nuclear fuel due to their potential to provide isolation from the surface environment on very long timescales. In 2011 the Swedish Nuclear Fuel & Waste Management Co. (SKB) submitted a license application for construction of a spent nuclear fuel repository. The disposal method involves disposing spent fuel in copper canisters with a cast iron insert at about 500 m depth in crystalline basement rock, and each canister is surrounded by a buffer of swelling bentonite clay. SKB's license application is supported by a post-closure safety assessment, SR-Site. SR-Site has been reviewed by the Swedish Radiation Safety Authority (SSM) for five years. The main method for review of SKB's license application is document review, which is carried out by SSM's staff and supported by SSM's external experts. The review has proven a challenging task due to its broad scope, complexity and multidisciplinary nature. SSM and its predecessors have, for several decades, been developing independent models to support regulatory reviews of post-closure safety assessments for geological repositories. For the review of SR-Site, SSM has developed a modelling approach with a structured application of independent modelling activities, including replication modelling, use of alternative conceptual models and bounding calculations, to complement the traditional document review. This paper describes this scheme and its application to biosphere and dose assessment modelling. SSM's independent modelling has provided important insights regarding quality and reasonableness of SKB's rather complex biosphere modelling and has helped quantifying conservatisms and highlighting conceptual uncertainty.

  6. Noise variance analysis using a flat panel x-ray detector: A method for additive noise assessment with application to breast CT applications

    PubMed Central

    Yang, Kai; Huang, Shih-Ying; Packard, Nathan J.; Boone, John M.

    2010-01-01

    Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system’s efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames∕s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system. PMID:20831059

  7. Noise variance analysis using a flat panel x-ray detector: A method for additive noise assessment with application to breast CT applications

    SciTech Connect

    Yang Kai; Huang, Shih-Ying; Packard, Nathan J.; Boone, John M.

    2010-07-15

    Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system's efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames/s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system.

  8. System and method for radiation dose calculation within sub-volumes of a monte carlo based particle transport grid

    DOEpatents

    Bergstrom, Paul M.; Daly, Thomas P.; Moses, Edward I.; Patterson, Jr., Ralph W.; Schach von Wittenau, Alexis E.; Garrett, Dewey N.; House, Ronald K.; Hartmann-Siantar, Christine L.; Cox, Lawrence J.; Fujino, Donald H.

    2000-01-01

    A system and method is disclosed for radiation dose calculation within sub-volumes of a particle transport grid. In a first step of the method voxel volumes enclosing a first portion of the target mass are received. A second step in the method defines dosel volumes which enclose a second portion of the target mass and overlap the first portion. A third step in the method calculates common volumes between the dosel volumes and the voxel volumes. A fourth step in the method identifies locations in the target mass of energy deposits. And, a fifth step in the method calculates radiation doses received by the target mass within the dosel volumes. A common volume calculation module inputs voxel volumes enclosing a first portion of the target mass, inputs voxel mass densities corresponding to a density of the target mass within each of the voxel volumes, defines dosel volumes which enclose a second portion of the target mass and overlap the first portion, and calculates common volumes between the dosel volumes and the voxel volumes. A dosel mass module, multiplies the common volumes by corresponding voxel mass densities to obtain incremental dosel masses, and adds the incremental dosel masses corresponding to the dosel volumes to obtain dosel masses. A radiation transport module identifies locations in the target mass of energy deposits. And, a dose calculation module, coupled to the common volume calculation module and the radiation transport module, for calculating radiation doses received by the target mass within the dosel volumes.

  9. Validation of an in-vivo proton beam range check method in an anthropomorphic pelvic phantom using dose measurements

    SciTech Connect

    Bentefour, El H. Prieels, Damien; Tang, Shikui; Cascio, Ethan W.; Testa, Mauro; Lu, Hsiao-Ming; Samuel, Deepak; Gottschalk, Bernard

    2015-04-15

    Purpose: In-vivo dosimetry and beam range verification in proton therapy could play significant role in proton treatment validation and improvements. In-vivo beam range verification, in particular, could enable new treatment techniques one of which could be the use of anterior fields for prostate treatment instead of opposed lateral fields as in current practice. This paper reports validation study of an in-vivo range verification method which can reduce the range uncertainty to submillimeter levels and potentially allow for in-vivo dosimetry. Methods: An anthropomorphic pelvic phantom is used to validate the clinical potential of the time-resolved dose method for range verification in the case of prostrate treatment using range modulated anterior proton beams. The method uses a 3 × 4 matrix of 1 mm diodes mounted in water balloon which are read by an ADC system at 100 kHz. The method is first validated against beam range measurements by dose extinction measurements. The validation is first completed in water phantom and then in pelvic phantom for both open field and treatment field configurations. Later, the beam range results are compared with the water equivalent path length (WEPL) values computed from the treatment planning system XIO. Results: Beam range measurements from both time-resolved dose method and the dose extinction method agree with submillimeter precision in water phantom. For the pelvic phantom, when discarding two of the diodes that show sign of significant range mixing, the two methods agree with ±1 mm. Only a dose of 7 mGy is sufficient to achieve this result. The comparison to the computed WEPL by the treatment planning system (XIO) shows that XIO underestimates the protons beam range. Quantifying the exact XIO range underestimation depends on the strategy used to evaluate the WEPL results. To our best evaluation, XIO underestimates the treatment beam range between a minimum of 1.7% and maximum of 4.1%. Conclusions: Time-resolved dose

  10. Validation of an in-vivo proton beam range check method in an anthropomorphic pelvic phantom using dose measurements

    PubMed Central

    Bentefour, El H.; Tang, Shikui; Cascio, Ethan W.; Testa, Mauro; Samuel, Deepak; Prieels, Damien; Gottschalk, Bernard; Lu, Hsiao-Ming

    2015-01-01

    Purpose: In-vivo dosimetry and beam range verification in proton therapy could play significant role in proton treatment validation and improvements. In-vivo beam range verification, in particular, could enable new treatment techniques one of which could be the use of anterior fields for prostate treatment instead of opposed lateral fields as in current practice. This paper reports validation study of an in-vivo range verification method which can reduce the range uncertainty to submillimeter levels and potentially allow for in-vivo dosimetry. Methods: An anthropomorphic pelvic phantom is used to validate the clinical potential of the time-resolved dose method for range verification in the case of prostrate treatment using range modulated anterior proton beams. The method uses a 3 × 4 matrix of 1 mm diodes mounted in water balloon which are read by an ADC system at 100 kHz. The method is first validated against beam range measurements by dose extinction measurements. The validation is first completed in water phantom and then in pelvic phantom for both open field and treatment field configurations. Later, the beam range results are compared with the water equivalent path length (WEPL) values computed from the treatment planning system XIO. Results: Beam range measurements from both time-resolved dose method and the dose extinction method agree with submillimeter precision in water phantom. For the pelvic phantom, when discarding two of the diodes that show sign of significant range mixing, the two methods agree with ±1 mm. Only a dose of 7 mGy is sufficient to achieve this result. The comparison to the computed WEPL by the treatment planning system (XIO) shows that XIO underestimates the protons beam range. Quantifying the exact XIO range underestimation depends on the strategy used to evaluate the WEPL results. To our best evaluation, XIO underestimates the treatment beam range between a minimum of 1.7% and maximum of 4.1%. Conclusions: Time-resolved dose

  11. NOTE: A sector-integration method for dose/MU calculation in a uniform scanning proton beam

    NASA Astrophysics Data System (ADS)

    Zhao, Qingya; Wu, Huanmei; Wolanski, Mark; Pack, Daniel; Johnstone, Peter A. S.; Das, Indra J.

    2010-02-01

    An accurate, simple and time-saving sector integration method for calculating the proton output (dose/monitor unit, MU) is presented based on the following treatment field parameters: aperture shape, aperture size, measuring position, beam range and beam modulation. The model is validated with dose/MU values for 431 fields previously measured at our center. The measurements were obtained in a uniform scanning proton beam with a parallel plate ionization chamber in a water phantom. For beam penetration depths of clinical interest (6-27 cm water), dose/MU values were measured as a function of spread-out Bragg peak (SOBP) extent and aperture diameter. First, 90 randomly selected fields were used to derive the model parameters, which were used to compute the dose/MU values for the remaining 341 fields. The min, max, average and the standard deviation of the difference between the calculated and the measured dose/MU values of the 341 fields were used to evaluate the accuracy and stability, for different energy ranges, aperture sizes, measurement positions and SOBP values. The experimental results of the five different functional sets showed that the calculation model is accurate with calculation errors ranging from -2.4% to 3.3%, and 99% of the errors are less than ±2%. The accuracy increases with higher energy, larger SOBP and bigger aperture size. The average error in the dose/MU calculation for small fields (field size <25 cm2) is 0.31 ± 0.96 (%).

  12. Evaluation of absorbed dose in irradiated sugar-containing plant material (peony roots) by an ESR method

    NASA Astrophysics Data System (ADS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2015-12-01

    The relationship between electron spin resonance (ESR) signal intensity of irradiated plant materials and sugar content was investigated by spectral analysis using peony roots. A weak background signal near g=2.005 was observed in the roots. After a 10 kGy irradiation, the ESR line broadened and the intensity increased, and the spectral characteristics were similar to a typical spectrum of irradiated food containing crystalline sugars. The free radical concentration was nearly stable 30 days after irradiation. The spectrum of peony root 30 days after irradiation was simulated using the summation of the intensities of six assumed components: radical signals derived from (a) sucrose, (b) glucose, (c) fructose, (d) cellulose, (e) the background signal near g=2.005 and (f) unidentified component. The simulated spectra using the six components were in agreement with the observed sample spectra. The intensity of sucrose radical signal in irradiated samples increased proportionally up to 20 kGy. In addition, the intensity of sucrose radical signals was strongly correlated with the sucrose contents of the samples. The results showed that the radiation sensitivity of sucrose in peony roots was influenced little by other plant constituents. There was also a good correlation between the total area of the spectra and the sucrose content, because the sucrose content was higher than that of other sugars in the samples. In peony roots, estimation of the absorbed dose from the ESR signal intensity may be possible by a calibration method based on the sucrose content.

  13. A habitat suitability model for Chinese sturgeon determined using the generalized additive method

    NASA Astrophysics Data System (ADS)

    Yi, Yujun; Sun, Jie; Zhang, Shanghong

    2016-03-01

    The Chinese sturgeon is a type of large anadromous fish that migrates between the ocean and rivers. Because of the construction of dams, this sturgeon's migration path has been cut off, and this species currently is on the verge of extinction. Simulating suitable environmental conditions for spawning followed by repairing or rebuilding its spawning grounds are effective ways to protect this species. Various habitat suitability models based on expert knowledge have been used to evaluate the suitability of spawning habitat. In this study, a two-dimensional hydraulic simulation is used to inform a habitat suitability model based on the generalized additive method (GAM). The GAM is based on real data. The values of water depth and velocity are calculated first via the hydrodynamic model and later applied in the GAM. The final habitat suitability model is validated using the catch per unit effort (CPUEd) data of 1999 and 2003. The model results show that a velocity of 1.06-1.56 m/s and a depth of 13.33-20.33 m are highly suitable ranges for the Chinese sturgeon to spawn. The hydraulic habitat suitability indexes (HHSI) for seven discharges (4000; 9000; 12,000; 16,000; 20,000; 30,000; and 40,000 m3/s) are calculated to evaluate integrated habitat suitability. The results show that the integrated habitat suitability reaches its highest value at a discharge of 16,000 m3/s. This study is the first to apply a GAM to evaluate the suitability of spawning grounds for the Chinese sturgeon. The study provides a reference for the identification of potential spawning grounds in the entire basin.

  14. Possibilities of CT Scanning as Analysis Method in Laser Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Karme, Aleksis; Kallonen, Aki; Matilainen, Ville-Pekka; Piili, Heidi; Salminen, Antti

    Laser additive manufacturing is an established and constantly developing technique. Structural assessment should be a key component to ensure directed evolution towards higher level of manufacturing. The macroscopic properties of metallic structures are determined by their internal microscopic features, which are difficult to assess using conventional surface measuring methodologies. X-ray microtomography (CT) is a promising technique for three-dimensional non-destructive probing of internal composition and build of various materials. Aim of this study is to define the possibilities of using CT scanning as quality control method in LAM fabricated parts. Since the parts fabricated with LAM are very often used in high quality and accuracy demanding applications in various industries such as medical and aerospace, it is important to be able to define the accuracy of the build parts. The tubular stainless steel test specimens were 3D modelled, manufactured with a modified research AM equipment and imaged after manufacturing with a high-power, high-resolution CT scanner. 3D properties, such as surface texture and the amount and distribution of internal pores, were also evaluated in this study. Surface roughness was higher on the interior wall of the tube, and deviation from the model was systematically directed towards the central axis. Pore distribution showed clear organization and divided into two populations; one following the polygon model seams along both rims, and the other being associated with the concentric and equidistant movement path of the laser. Assessment of samples can enhance the fabrication by guiding the improvement of both modelling and manufacturing process.

  15. A two-dose-rate method for general recombination correction for liquid ionization chambers in pulsed beams

    NASA Astrophysics Data System (ADS)

    Tölli, Heikki; Sjögren, Rickard; Wendelsten, Mikael

    2010-08-01

    The correction for general recombination losses in liquid ionization chambers (LICs) is more complex than that in air-filled ionization chambers. The reason for this is that the saturation charge in LICs, i.e. the charge that escapes initial recombination, depends on the applied voltage. This paper presents a method, based on measurements at two different dose rates in a pulsed beam, for general recombination correction in LICs. The Boag theory for pulsed beams is used and the collection efficiency is determined by numerical methods which are equivalent to the two-voltage method used in dosimetry with air-filled ionization chambers. The method has been tested in experiments in water in a 20 MeV electron beam using two LICs filled with isooctane and tetramethylsilane. The dose per pulse in the electron beam was varied between 0.1 mGy/pulse and 8 mGy/pulse. The relative standard deviations of the collection efficiencies determined with the two-dose-rate method ranged between 0.1% and 1.5%. The dose-rate variations of the general recombination corrected charge measured with the LICs are in excellent agreement with the corresponding values obtained with an air-filled plane parallel ionization chamber.

  16. Analysis methods for the determination of anthropogenic additions of P to agricultural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus additions and measurement in soil is of concern on lands where biosolids have been applied. Colorimetric analysis for plant-available P may be inadequate for the accurate assessment of soil P. Phosphate additions in a regulatory environment need to be accurately assessed as the reported...

  17. First-Grade Methods of Single-Digit Addition with Two or More Addends

    ERIC Educational Resources Information Center

    Guerrero, Shannon M.; Palomaa, Kimberly

    2012-01-01

    In an attempt to further understand connections between children's proficiency and development with single- and multidigit addition, this study investigated the conceptualizations and solution strategies of 26 first-graders presented with several single-digit, multiple addend addition problems. The changes in students' solution strategies over the…

  18. Estimation of effective doses to adult and pediatric patients from multislice computed tomography: A method based on energy imparted

    SciTech Connect

    Theocharopoulos, Nicholas; Damilakis, John; Perisinakis, Kostas; Tzedakis, Antonis; Karantanas, Apostolos; Gourtsoyiannis, Nicholas

    2006-10-15

    The purpose of this study is to provide a method and required data for the estimation of effective dose (E) values to adult and pediatric patients from computed tomography (CT) scans of the head, chest abdomen, and pelvis, performed on multi-slice scanners. Mean section radiation dose (d{sub m}) to cylindrical water phantoms of varying radius normalized over CT dose index free-in-air (CTDI{sub F}) were calculated for the head and body scanning modes of a multislice scanner with use of Monte Carlo techniques. Patients were modeled as equivalent water phantoms and the energy imparted ({epsilon}) to simulated pediatric and adult patients was calculated on the basis of measured CTDI{sub F} values. Body region specific energy imparted to effective dose conversion coefficients (E/{epsilon}) for adult male and female patients were generated from previous data. Effective doses to patients aged newborn to adult were derived for all available helical and axial beam collimations, taking into account age specific patient mass and scanning length. Depending on high voltage, body region, and patient sex, E/{epsilon} values ranged from 0.008 mSv/mJ for head scans to 0.024 mSv/mJ for chest scans. When scanned with the same technique factors as the adults, pediatric patients absorb as little as 5% of the energy imparted to adults, but corresponding effective dose values are up to a factor of 1.6 higher. On average, pediatric patients absorb 44% less energy per examination but have a 24% higher effective dose, compared with adults. In clinical practice, effective dose values to pediatric patients are 2.5 to 10 times lower than in adults due to the adaptation of tube current. A method is provided for the calculation of effective dose to adult and pediatric patients on the basis of individual patient characteristics such as sex, mass, dimensions, and density of imaged anatomy, and the technical features of modern multislice scanners. It allows the optimum selection of scanning

  19. A method to dynamically balance intensity modulated radiotherapy dose between organs-at-risk.

    PubMed

    Das, Shiva K

    2009-05-01

    The IMRT treatment planning process typically follows a path that is based on the manner in which the planner interactively adjusts the target and organ-at-risk (OAR) constraints and priorities. The time-intensive nature of this process restricts the planner from fully understanding the dose tradeoff between structures, making it unlikely that the resulting plan fully exploits the extent to which dose can be redistributed between anatomical structures. Multiobjective Pareto optimization has been used in the past to enable the planner to more thoroughly explore alternatives in dose trade-off by combining pre-generated Pareto optimal solutions in real time, thereby potentially tailoring a plan more exactly to requirements. However, generating the Pareto optimal solutions can be nonintuitive and computationally time intensive. The author presents an intuitive and fast non-Pareto approach for generating optimization sequences (prior to planning), which can then be rapidly combined by the planner in real time to yield a satisfactory plan. Each optimization sequence incrementally reduces dose to one OAR at a time, starting from the optimization solution where dose to all OARs are reduced with equal priority, until user-specified target coverage limits are violated. The sequences are computationally efficient to generate, since the optimization at each position along a sequence is initiated from the end result of the previous position in the sequence. The pre-generated optimization sequences require no user interaction. In real time, a planner can more or less instantaneously visualize a treatment plan by combining the dose distributions corresponding to user-selected positions along each of the optimization sequences (target coverage is intrinsically maintained in the combination). Interactively varying the selected positions along each of the sequences enables the planner to rapidly understand the nature of dose trade-off between structures and, thereby, arrive at a

  20. A method to dynamically balance intensity modulated radiotherapy dose between organs-at-risk

    SciTech Connect

    Das, Shiva K.

    2009-05-15

    The IMRT treatment planning process typically follows a path that is based on the manner in which the planner interactively adjusts the target and organ-at-risk (OAR) constraints and priorities. The time-intensive nature of this process restricts the planner from fully understanding the dose trade-off between structures, making it unlikely that the resulting plan fully exploits the extent to which dose can be redistributed between anatomical structures. Multiobjective Pareto optimization has been used in the past to enable the planner to more thoroughly explore alternatives in dose trade-off by combining pre-generated Pareto optimal solutions in real time, thereby potentially tailoring a plan more exactly to requirements. However, generating the Pareto optimal solutions can be nonintuitive and computationally time intensive. The author presents an intuitive and fast non-Pareto approach for generating optimization sequences (prior to planning), which can then be rapidly combined by the planner in real time to yield a satisfactory plan. Each optimization sequence incrementally reduces dose to one OAR at a time, starting from the optimization solution where dose to all OARs are reduced with equal priority, until user-specified target coverage limits are violated. The sequences are computationally efficient to generate, since the optimization at each position along a sequence is initiated from the end result of the previous position in the sequence. The pre-generated optimization sequences require no user interaction. In real time, a planner can more or less instantaneously visualize a treatment plan by combining the dose distributions corresponding to user-selected positions along each of the optimization sequences (target coverage is intrinsically maintained in the combination). Interactively varying the selected positions along each of the sequences enables the planner to rapidly understand the nature of dose trade-off between structures and, thereby, arrive at a

  1. Statistical methods for clinical verification of dose response parameters related to esophageal stricture and AVM obliteration from radiotherapy

    NASA Astrophysics Data System (ADS)

    Mavroidis, Panayiotis; Lind, Bengt K.; Theodorou, Kyriaki; Laurell, Göran; Fernberg, Jan-Olof; Lefkopoulos, Dimitrios; Kappas, Constantin; Brahme, Anders

    2004-08-01

    The purpose of this work is to provide some statistical methods for evaluating the predictive strength of radiobiological models and the validity of dose-response parameters for tumour control and normal tissue complications. This is accomplished by associating the expected complication rates, which are calculated using different models, with the clinical follow-up records. These methods are applied to 77 patients who received radiation treatment for head and neck cancer and 85 patients who were treated for arteriovenous malformation (AVM). The three-dimensional dose distribution delivered to esophagus and AVM nidus and the clinical follow-up results were available for each patient. Dose-response parameters derived by a maximum likelihood fitting were used as a reference to evaluate their compatibility with the examined treatment methodologies. The impact of the parameter uncertainties on the dose-response curves is demonstrated. The clinical utilization of the radiobiological parameters is illustrated. The radiobiological models (relative seriality and linear Poisson) and the reference parameters are validated to prove their suitability in reproducing the treatment outcome pattern of the patient material studied (through the probability of finding a worse fit, area under the ROC curve and khgr2 test). The analysis was carried out for the upper 5 cm of the esophagus (proximal esophagus) where all the strictures are formed, and the total volume of AVM. The estimated confidence intervals of the dose-response curves appear to have a significant supporting role on their clinical implementation and use.

  2. A method to reduce patient's eye lens dose in neuro-interventional radiology procedures

    NASA Astrophysics Data System (ADS)

    Safari, M. J.; Wong, J. H. D.; Kadir, K. A. A.; Sani, F. M.; Ng, K. H.

    2016-08-01

    Complex and prolonged neuro-interventional radiology procedures using the biplane angiography system increase the patient's risk of radiation-induced cataract. Physical collimation is the most effective way of reducing the radiation dose to the patient's eye lens, but in instances where collimation is not possible, an attenuator may be useful in protecting the eyes. In this study, an eye lens protector was designed and fabricated to reduce the radiation dose to the patients' eye lens during neuro-interventional procedures. The eye protector was characterised before being tested on its effectiveness in a simulated aneurysm procedure on an anthropomorphic phantom. Effects on the automatic dose rate control (ADRC) and image quality are also evaluated. The eye protector reduced the radiation dose by up to 62.1% at the eye lens. The eye protector is faintly visible in the fluoroscopy images and increased the tube current by a maximum of 3.7%. It is completely invisible in the acquisition mode and does not interfere with the clinical procedure. The eye protector placed within the radiation field of view was able to reduce the radiation dose to the eye lens by direct radiation beam of the lateral x-ray tube with minimal effect on the ADRC system.

  3. 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) Dose-Response Studies: Preliminary Literature Search Results and Request for Additional Studies

    EPA Science Inventory

    EPA invited the public to comment on the preliminary list of in vivo mammalian dose-response citations for 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). This list was compiled as a first step in the development of EPA’s response to the National Academy of Sciences comments (NAS, 2...

  4. Bifurcated method and apparatus for floating point addition with decreased latency time

    DOEpatents

    Farmwald, Paul M.

    1987-01-01

    Apparatus for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

  5. SU-E-T-57: A Novel Method to Improve Dose Heterogeneity of Target and Organs at Risk Sparing in the Intensity-Modulated Radiotherapy for Stage III Lung Cancer

    SciTech Connect

    Huang, B-T; Lu, J-Y

    2015-06-15

    Purpose: Intensity-modulated radiotherapy (IMRT) treatment for lung cancer is difficult due to the heterogeneous dose distribution and excessive dose to the organs at risk (OARs). We introduce a simple method based on the base dose function (BDF) in Eclipse treatment planning system to overcome the difficulties. Methods: Thirteen patients suffered from stage III non-small cell lung cancer (NSCLC) were enrolled in the study. Three kinds of approaches were applied to obtain clinically acceptable treatment plans: 1) conventionally optimizing method with hot and cold spots re-optimization (CO); 2) target-divided optimizing method (TDO) in which the optimization objective in the lung density of planning target volume (PTV) was set to 2 to 4 Gy higher than in the soft tissue density; 3) base dose function (BDF) in which the treatment plan was produced based on the original plan for re-optimization. CO, TDO and BDF methods were then compared in terms of conformity index (CI), homogeneity index (HI), OARs sparing and monitor units (MUs). Additionally, delta4, portal dosimetry and IMSure were used to measure the dose delivering accuracy. Results: The BDF technique provided more superior CI and HI than the other two methods. Moreover, the new method also reduced the lung, esophagus, heart and spinal cord dose. However, the BDF plans needed extra 15% and 10% MUs than the CO and TDO methods. Dose verification results demonstrated good and comparable γ pass rates among the three methods. Conclusion: The proposed BDF method greatly improves the dose homogeneity and OARs sparing in the IMRT treatment for lung cancer.

  6. Reanalysis of cancer mortality in Japanese A-bomb survivors exposed to low doses of radiation: bootstrap and simulation methods

    PubMed Central

    2009-01-01

    Background The International Commission on Radiological Protection (ICRP) recommended annual occupational dose limit is 20 mSv. Cancer mortality in Japanese A-bomb survivors exposed to less than 20 mSv external radiation in 1945 was analysed previously, using a latency model with non-linear dose response. Questions were raised regarding statistical inference with this model. Methods Cancers with over 100 deaths in the 0 - 20 mSv subcohort of the 1950-1990 Life Span Study are analysed with Poisson regression models incorporating latency, allowing linear and non-linear dose response. Bootstrap percentile and Bias-corrected accelerated (BCa) methods and simulation of the Likelihood Ratio Test lead to Confidence Intervals for Excess Relative Risk (ERR) and tests against the linear model. Results The linear model shows significant large, positive values of ERR for liver and urinary cancers at latencies from 37 - 43 years. Dose response below 20 mSv is strongly non-linear at the optimal latencies for the stomach (11.89 years), liver (36.9), lung (13.6), leukaemia (23.66), and pancreas (11.86) and across broad latency ranges. Confidence Intervals for ERR are comparable using Bootstrap and Likelihood Ratio Test methods and BCa 95% Confidence Intervals are strictly positive across latency ranges for all 5 cancers. Similar risk estimates for 10 mSv (lagged dose) are obtained from the 0 - 20 mSv and 5 - 500 mSv data for the stomach, liver, lung and leukaemia. Dose response for the latter 3 cancers is significantly non-linear in the 5 - 500 mSv range. Conclusion Liver and urinary cancer mortality risk is significantly raised using a latency model with linear dose response. A non-linear model is strongly superior for the stomach, liver, lung, pancreas and leukaemia. Bootstrap and Likelihood-based confidence intervals are broadly comparable and ERR is strictly positive by bootstrap methods for all 5 cancers. Except for the pancreas, similar estimates of latency and risk from 10

  7. Three-dimensional Finite Elements Method simulation of Total Ionizing Dose in 22 nm bulk nFinFETs

    NASA Astrophysics Data System (ADS)

    Chatzikyriakou, Eleni; Potter, Kenneth; Redman-White, William; De Groot, C. H.

    2017-02-01

    Finite Elements Method simulation of Total Ionizing Dose effects on 22 nm bulk Fin Field Effect Transistor (FinFET) devices using the commercial software Synopsys Sentaurus TCAD is presented. The simulation parameters are extracted by calibrating the charge trapping model to experimental results on 400 nm SiO2 capacitors irradiated under zero bias. The FinFET device characteristics are calibrated to the Intel 22 nm bulk technology. Irradiation simulations of the transistor performed with all terminals unbiased reveal increased hardness up to a total dose of 1 MRad(SiO2).

  8. Nuclear medicine dose equivalent a method for determination of radiation risk

    SciTech Connect

    Huda, W.

    1986-12-01

    Conventional nuclear medicine dosimetry involves specifying individual organ doses. The difficulties that can arise with this approach to radiation dosimetry are discussed. An alternative scheme is described that is based on the ICRP effective dose equivalent, H/sub E/, and which is a direct estimate of the average radiation risk to the patient. The mean value of H/sub E/ for seven common /sup 99m/Tc nuclear medicine procedures is 0.46 rem and the average radiation risk from this level of exposure is estimated to be comparable to the risk from smoking approx. 28 packs of cigarettes or driving approx. 1300 miles.

  9. Generalized net analyte signal standard addition as a novel method for simultaneous determination: application in spectrophotometric determination of some pesticides.

    PubMed

    Asadpour-Zeynali, Karim; Saeb, Elhameh; Vallipour, Javad; Bamorowat, Mehdi

    2014-01-01

    Simultaneous spectrophotometric determination of three neonicotinoid insecticides (acetamiprid, imidacloprid, and thiamethoxam) by a novel method named generalized net analyte signal standard addition method (GNASSAM) in some binary and ternary synthetic mixtures was investigated. For this purpose, standard addition was performed using a single standard solution consisting of a mixture of standards of all analytes. Savings in time and amount of used materials are some of the advantages of this method. All determinations showed appropriate applicability of this method with less than 5% error. This method may be applied for linearly dependent data in the presence of known interferents. The GNASSAM combines the advantages of both the generalized standard addition method and net analyte signal; therefore, it may be a proper alternative for some other multivariate methods.

  10. Method for measuring dose-equivalent in a neutron flux with an unknown energy spectra and means for carrying out that method

    DOEpatents

    Distenfeld, Carl H.

    1978-01-01

    A method for measuring the dose-equivalent for exposure to an unknown and/or time varing neutron flux which comprises simultaneously exposing a plurality of neutron detecting elements of different types to a neutron flux and combining the measured responses of the various detecting elements by means of a function, whose value is an approximate measure of the dose-equivalent, which is substantially independent of the energy spectra of the flux. Also, a personnel neutron dosimeter, which is useful in carrying out the above method, comprising a plurality of various neutron detecting elements in a single housing suitable for personnel to wear while working in a radiation area.

  11. Further Insight and Additional Inference Methods for Polynomial Regression Applied to the Analysis of Congruence

    ERIC Educational Resources Information Center

    Cohen, Ayala; Nahum-Shani, Inbal; Doveh, Etti

    2010-01-01

    In their seminal paper, Edwards and Parry (1993) presented the polynomial regression as a better alternative to applying difference score in the study of congruence. Although this method is increasingly applied in congruence research, its complexity relative to other methods for assessing congruence (e.g., difference score methods) was one of the…

  12. Dosimetry in radiotherapy using a-Si EPIDs: Systems, methods, and applications focusing on 3D patient dose estimation

    NASA Astrophysics Data System (ADS)

    McCurdy, B. M. C.

    2013-06-01

    An overview is provided of the use of amorphous silicon electronic portal imaging devices (EPIDs) for dosimetric purposes in radiation therapy, focusing on 3D patient dose estimation. EPIDs were originally developed to provide on-treatment radiological imaging to assist with patient setup, but there has also been a natural interest in using them as dosimeters since they use the megavoltage therapy beam to form images. The current generation of clinically available EPID technology, amorphous-silicon (a-Si) flat panel imagers, possess many characteristics that make them much better suited to dosimetric applications than earlier EPID technologies. Features such as linearity with dose/dose rate, high spatial resolution, realtime capability, minimal optical glare, and digital operation combine with the convenience of a compact, retractable detector system directly mounted on the linear accelerator to provide a system that is well-suited to dosimetric applications. This review will discuss clinically available a-Si EPID systems, highlighting dosimetric characteristics and remaining limitations. Methods for using EPIDs in dosimetry applications will be discussed. Dosimetric applications using a-Si EPIDs to estimate three-dimensional dose in the patient during treatment will be overviewed. Clinics throughout the world are implementing increasingly complex treatments such as dynamic intensity modulated radiation therapy and volumetric modulated arc therapy, as well as specialized treatment techniques using large doses per fraction and short treatment courses (ie. hypofractionation and stereotactic radiosurgery). These factors drive the continued strong interest in using EPIDs as dosimeters for patient treatment verification.

  13. Monte Carlo modeling of proton therapy installations: a global experimental method to validate secondary neutron dose calculations

    NASA Astrophysics Data System (ADS)

    Farah, J.; Martinetti, F.; Sayah, R.; Lacoste, V.; Donadille, L.; Trompier, F.; Nauraye, C.; De Marzi, L.; Vabre, I.; Delacroix, S.; Hérault, J.; Clairand, I.

    2014-06-01

    Monte Carlo calculations are increasingly used to assess stray radiation dose to healthy organs of proton therapy patients and estimate the risk of secondary cancer. Among the secondary particles, neutrons are of primary concern due to their high relative biological effectiveness. The validation of Monte Carlo simulations for out-of-field neutron doses remains however a major challenge to the community. Therefore this work focused on developing a global experimental approach to test the reliability of the MCNPX models of two proton therapy installations operating at 75 and 178 MeV for ocular and intracranial tumor treatments, respectively. The method consists of comparing Monte Carlo calculations against experimental measurements of: (a) neutron spectrometry inside the treatment room, (b) neutron ambient dose equivalent at several points within the treatment room, (c) secondary organ-specific neutron doses inside the Rando-Alderson anthropomorphic phantom. Results have proven that Monte Carlo models correctly reproduce secondary neutrons within the two proton therapy treatment rooms. Sensitive differences between experimental measurements and simulations were nonetheless observed especially with the highest beam energy. The study demonstrated the need for improved measurement tools, especially at the high neutron energy range, and more accurate physical models and cross sections within the Monte Carlo code to correctly assess secondary neutron doses in proton therapy applications.

  14. Benchmarking of the dose planning method (DPM) Monte Carlo code using electron beams from a racetrack microtron.

    PubMed

    Chetty, Indrin J; Moran, Jean M; McShan, Daniel L; Fraass, Benedick A; Wilderman, Scott J; Bielajew, Alex F

    2002-06-01

    A comprehensive set of measurements and calculations has been conducted to investigate the accuracy of the Dose Planning Method (DPM) Monte Carlo code for dose calculations from 10 and 50 MeV scanned electron beams produced from a racetrack microtron. Central axis depth dose measurements and a series of profile scans at various depths were acquired in a water phantom using a Scanditronix type RK ion chamber. Source spatial distributions for the Monte Carlo calculations were reconstructed from in-air ion chamber measurements carried out across the two-dimensional beam profile at 100 cm downstream from the source. The in-air spatial distributions were found to have full width at half maximum of 4.7 and 1.3 cm, at 100 cm from the source, for the 10 and 50 MeV beams, respectively. Energy spectra for the 10 and 50 MeV beams were determined by simulating the components of the microtron treatment head using the code MCNP4B. DPM calculations are on average within +/- 2% agreement with measurement for all depth dose and profile comparisons conducted in this study. The accuracy of the DPM code illustrated in this work suggests that DPM may be used as a valuable tool for electron beam dose calculations.

  15. Monte Carlo modeling of proton therapy installations: a global experimental method to validate secondary neutron dose calculations.

    PubMed

    Farah, J; Martinetti, F; Sayah, R; Lacoste, V; Donadille, L; Trompier, F; Nauraye, C; De Marzi, L; Vabre, I; Delacroix, S; Hérault, J; Clairand, I

    2014-06-07

    Monte Carlo calculations are increasingly used to assess stray radiation dose to healthy organs of proton therapy patients and estimate the risk of secondary cancer. Among the secondary particles, neutrons are of primary concern due to their high relative biological effectiveness. The validation of Monte Carlo simulations for out-of-field neutron doses remains however a major challenge to the community. Therefore this work focused on developing a global experimental approach to test the reliability of the MCNPX models of two proton therapy installations operating at 75 and 178 MeV for ocular and intracranial tumor treatments, respectively. The method consists of comparing Monte Carlo calculations against experimental measurements of: (a) neutron spectrometry inside the treatment room, (b) neutron ambient dose equivalent at several points within the treatment room, (c) secondary organ-specific neutron doses inside the Rando-Alderson anthropomorphic phantom. Results have proven that Monte Carlo models correctly reproduce secondary neutrons within the two proton therapy treatment rooms. Sensitive differences between experimental measurements and simulations were nonetheless observed especially with the highest beam energy. The study demonstrated the need for improved measurement tools, especially at the high neutron energy range, and more accurate physical models and cross sections within the Monte Carlo code to correctly assess secondary neutron doses in proton therapy applications.

  16. An Inventory of Methods for the Assessment of Additive Increased Addictiveness of Tobacco Products

    PubMed Central

    van de Nobelen, Suzanne; Kienhuis, Anne S.

    2016-01-01

    Background: Cigarettes and other forms of tobacco contain the addictive drug nicotine. Other components, either naturally occurring in tobacco or additives that are intentionally added during the manufacturing process, may add to the addictiveness of tobacco products. As such, these components can make cigarette smokers more easily and heavily dependent. Efforts to regulate tobacco product dependence are emerging globally. Additives that increase tobacco dependence will be prohibited under the new European Tobacco Product Directive. Objective: This article provides guidelines and recommendations for developing a regulatory strategy for assessment of increase in tobacco dependence due to additives. Relevant scientific literature is summarized and criteria and experimental studies that can define increased dependence of tobacco products are described. Conclusions: Natural tobacco smoke is a very complex matrix of components, therefore analysis of the contribution of an additive or a combination of additives to the level of dependence on this product is challenging. We propose to combine different type of studies analyzing overall tobacco product dependence potential and the functioning of additives in relation to nicotine. By using a combination of techniques, changes associated with nicotine dependence such as behavioral, physiological, and neurochemical alterations can be examined to provide sufficient information. Research needs and knowledge gaps will be discussed and recommendations will be made to translate current knowledge into legislation. As such, this article aids in implementation of the Tobacco Product Directive, as well as help enable regulators and researchers worldwide to develop standards to reduce dependence on tobacco products. Implications: This article provides an overall view on how to assess tobacco product constituents for their potential contribution to use and dependence. It provides guidelines that help enable regulators worldwide to

  17. Methods for estimating doses to organisms from radioactive materials released into the aquatic environment

    SciTech Connect

    Baker, D.A.; Soldat, J.K.

    1992-06-01

    The US Department of Energy recently published an interim dose limit of 1 rad d{sup {minus}1} for controlling the radiation exposure of nature aquatic organisms. A computer program named CRITR, developed previously for calculating radiation doses to aquatic organisms and their predators, has been updated as an activity of the Hanford Site Surface Environmental Surveillance Project to facilitate demonstration of compliance with this limit. This report presents the revised models and the updated computer program, CRITR2, for the assessment of radiological doses to aquatic organisms and their predators; tables of the required input parameters are also provided. Both internal and external doses to fish, crustacea, mollusks, and algae, as well as organisms that subsist on them, such as muskrats, raccoons, and ducks, may be estimated using CRITR2. Concentrations of radionuclides in the water to which the organisms are exposed may be entered directly into the user-input file or may be calculated from a source term and standard dilution models developed for the National Council on Radiation Protection and Measurements.

  18. BEDVH--A method for evaluating biologically effective dose volume histograms: Application to eye plaque brachytherapy implants

    SciTech Connect

    Gagne, Nolan L.; Leonard, Kara L.; Huber, Kathryn E.; Mignano, John E.; Duker, Jay S.; Laver, Nora V.; Rivard, Mark J.

    2012-02-15

    Purpose: A method is introduced to examine the influence of implant duration T, radionuclide, and radiobiological parameters on the biologically effective dose (BED) throughout the entire volume of regions of interest for episcleral brachytherapy using available radionuclides. This method is employed to evaluate a particular eye plaque brachytherapy implant in a radiobiological context. Methods: A reference eye geometry and 16 mm COMS eye plaque loaded with {sup 103}Pd, {sup 125}I, or {sup 131}Cs sources were examined with dose distributions accounting for plaque heterogeneities. For a standardized 7 day implant, doses to 90% of the tumor volume ( {sub TUMOR}D{sub 90}) and 10% of the organ at risk volumes ( {sub OAR}D{sub 10}) were calculated. The BED equation from Dale and Jones and published {alpha}/{beta} and {mu} parameters were incorporated with dose volume histograms (DVHs) for various T values such as T = 7 days (i.e., {sub TUMOR} {sup 7}BED{sub 10} and {sub OAR} {sup 7}BED{sub 10}). By calculating BED throughout the volumes, biologically effective dose volume histograms (BEDVHs) were developed for tumor and OARs. Influence of T, radionuclide choice, and radiobiological parameters on {sub TUMOR}BEDVH and {sub OAR}BEDVH were examined. The nominal dose was scaled for shorter implants to achieve biological equivalence. Results: {sub TUMOR}D{sub 90} values were 102, 112, and 110 Gy for {sup 103}Pd, {sup 125}I, and {sup 131}Cs, respectively. Corresponding {sub TUMOR} {sup 7}BED{sub 10} values were 124, 140, and 138 Gy, respectively. As T decreased from 7 to 0.01 days, the isobiologically effective prescription dose decreased by a factor of three. As expected, {sub TUMOR} {sup 7}BEDVH did not significantly change as a function of radionuclide half-life but varied by 10% due to radionuclide dose distribution. Variations in reported radiobiological parameters caused {sub TUMOR} {sup 7}BED{sub 10} to deviate by up to 46%. Over the range of {sub OAR

  19. A robust method for determining the absorbed dose to water in a phantom for low-energy photon radiation

    NASA Astrophysics Data System (ADS)

    Schneider, T.

    2011-06-01

    The application of more and more low-energy photon radiation in brachytherapy—either in the form of low-dose-rate radioactive seeds such as Pd-103 or I-125 or in the form of miniature x-ray tubes—has induced greater interest in determining the absorbed dose to water in water in this energy range. As it seems to be hardly feasible to measure the absorbed dose with calorimetric methods in this low energy range, ionometric methods are the preferred choice. However, the determination of the absorbed dose to water in water by ionometric methods is difficult in this energy range. With decreasing energy, the relative uncertainty of the photon cross sections increases and as the mass energy transfer coefficients show a steep gradient, the spectra of the radiation field must be known precisely. In this work two ionometric methods to determine the absorbed dose to water are evaluated with respect to their sensitivity to the uncertainties of the spectra and of the atomic database. The first is the measurement of the air kerma free in air and the application of an MC-based conversion factor to the absorbed dose to water. The second is the determination of the absorbed dose to water by means of an extrapolation chamber as an integral part of a phantom. In the complementing MC-calculations, two assortments of spectra each of which is based on a separate unfolding procedure were used as well as two kinds of databases: the standard PEGS and the recently implemented NIST database of EGSnrc. Experimental results were obtained by using a parallel-plate graphite extrapolation chamber and a free-air chamber. In the case when the water kerma in a phantom is determined from the measurements of air kerma free in air, differences in the order of 10% were found, according to which the database or the kind of spectrum is used. In contrast to this, for the second method, the differences found were about 0.5%.

  20. Biological Dose Response to PM2.5: Effect of Particle Extraction Method on Platelet and Lung Responses

    PubMed Central

    Van Winkle, Laura S.; Bein, Keith; Anderson, Donald; Pinkerton, Kent E.; Tablin, Fern; Wilson, Dennis; Wexler, Anthony S.

    2015-01-01

    Particulate matter (PM) exposure contributes to respiratory diseases and cardiopulmonary mortality. PM toxicity is related to sources and composition, such as abundance of polycyclic aromatic hydrocarbons (PAHs). We exposed adult male BALB/c mice, via oropharyngeal aspiration, to a range of doses of PM2.5 collected during the winter in downtown Sacramento near a major freeway interchange (SacPM). Two preparation methods (spin-down and multi-solvent extraction) were tested to remove particles from collection filters. Three doses were analyzed 24 h after treatment for (1) leukocytes and total protein in bronchoalveolar lavage fluid (BALF), (2) airway-specific and whole lobe expression of PAH-sensitive genes (CYP1B1 and CYP1A1) and IL-1 b, (3) lung histology, and (4) platelet function. Both extraction methods stimulated biological responses, but the spin-down method was more robust at producing IL-1 b and CYP1B1 gene responses and the multi-solvent extraction induced whole lung CYP1A1. Neutrophils in the BALF were increased 5- to 10-fold at the mid and high dose for both preparations. Histopathology scores indicated dose-dependent responses and increased pathology associated with spin-down-derived PM exposure. In microdissected airways, spin-down PM increased CYP1B1 gene expression significantly, but multi-solvent extracted PM did not. Platelet responses to the physiological agonist thrombin were approximately twice as potent in the spin-down preparation as in the multi-solvent extract. We conclude (1) the method of filter extraction can influence the degree of biological response, (2) for SacPM the minimal effective dose is 27.5–50 µg based on neutrophil recruitment, and (3) P450s are upregulated differently in airways and lung parenchyma in response to PAH-containing PM. PMID:25389146

  1. Thermodynamic method of calculating the effect of alloying additives on interphase interaction in composite materials

    NASA Technical Reports Server (NTRS)

    Tuchinsky, L. I.

    1986-01-01

    The effect of alloying additives to the matrix of a composite on the high temperature solubility rate of a single component fiber was analyzed thermodynamically. With an example of binary Ni alloys, with Group IV-VI transition metals reinforced with W fibers, agreement between the calculated and experimental data was demonstrated.

  2. Methods of Measuring Vapor Pressures of Lubricants With Their Additives Using TGA and/or Microbalances

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.; Miller, Michael K.; Montoya, Alex F.

    1996-01-01

    The life of a space system may be critically dependent on the lubrication of some of its moving parts. The vapor pressure, the quantity of the available lubricant, the temperature and the exhaust venting conductance passage are important considerations in the selection and application of a lubricant. In addition, the oil additives employed to provide certain properties of low friction, surface tension, antioxidant and load bearing characteristics, are also very important and need to be known with regard to their amounts and vapor pressures. This paper reports on the measurements and analyses carried out to obtain those parameters for two often employed lubricants, the Apiezon(TM)-C and the Krytox(TM) AB. The measurements were made employing an electronic microbalance and a thermogravimetric analyzer (TGA) modified to operate in a vacuum. The results have been compared to other data on these oils when available. The identification of the mass fractions of the additives in the oil and their vapor pressures as a function of the temperature were carried out. These may be used to estimate the lubricant life given its quantity and the system vent exhaust conductance. It was found that the Apiezon(TM)-C has three main components with different rates of evaporation while the Krytox(TM) did not indicate any measurable additive.

  3. Implantation of additional defibrillation lead into the coronary sinus: an effective method of decreasing defibrillation threshold.

    PubMed

    Wilczek, Rajmund; Swiątkowski, Maciej; Czepiel, Aleksandra; Sterliński, Maciej; Makowska, Ewa; Kułakowski, Piotr

    2011-01-01

    We report a case of successful implantation of an additional defibrillation lead into the coronary sinus due to high defibrillation threshold (DFT) in a seriously ill patient with a history of extensive myocardial infarction referred for implantable cardioverter- defibrillator implantation after an episode of unstable ventricular tachycardia. All previous attempts to reduce DFT, including subcutaneous electrode implantation, had been unsuccessful.

  4. The addition of computer simulated noise to investigate radiation dose and image quality in images with spatial correlation of statistical noise: an example application to X-ray CT of the brain.

    PubMed

    Britten, A J; Crotty, M; Kiremidjian, H; Grundy, A; Adam, E J

    2004-04-01

    This study validates a method to add spatially correlated statistical noise to an image, applied to transaxial X-ray CT images of the head to simulate exposure reduction by up to 50%. 23 patients undergoing routine head CT had three additional slices acquired for validation purposes, two at the same clinical 420 mAs exposure and one at 300 mAs. Images at the level of the cerebrospinal fluid filled ventricles gave readings of noise from a single image, with subtraction of image pairs to obtain noise readings from non-uniform tissue regions. The spatial correlation of the noise was determined and added to the acquired 420 mAs image to simulate images at 340 mAs, 300 mAs, 260 mAs and 210 mAs. Two radiologists assessed the images, finding little difference between the 300 mAs simulated and acquired images. The presence of periventricular low density lesions (PVLD) was used as an example of the effect of simulated dose reduction on diagnostic accuracy, and visualization of the internal capsule was used as a measure of image quality. Diagnostic accuracy for the diagnosis of PVLD did not fall significantly even down to 210 mAs, though visualization of the internal capsule was poorer at lower exposure. Further work is needed to investigate means of measuring statistical noise without the need for uniform tissue areas, or image pairs. This technique has been shown to allow sufficiently accurate simulation of dose reduction and image quality degradation, even when the statistical noise is spatially correlated.

  5. Activity Approach to the Formation of the Method of Addition and Subtraction in Elementary Students

    ERIC Educational Resources Information Center

    Maksimov, L. K.; Maksimova, L. V.

    2013-01-01

    One of the main tasks in teaching mathematics to elementary students is to form calculating methods and techniques. The efforts of teachers and methodologists are aimed at solving this problem. Educational and psychological research is devoted to it. At the same time school teaching experience demonstrates some difficulties in learning methods of…

  6. MAGNETOMETRY, SELF-POTENTIAL, AND SEISMIC - ADDITIONAL GEOPHYSICAL METHODS HAVING POTENTIALLY SIGNIFICANT FUTURE UTILIZATION IN AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods can provide important information in agricultural settings, and the use of these techniques are becoming more and more widespread. Magnetrometry, self-potential, and seismic are three geophysical methods, all of which have the potential for substantial future use in agriculture, ...

  7. A method for high-energy, low-dose mammography using edge illumination x-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Diemoz, Paul C.; Bravin, Alberto; Sztrókay-Gaul, Anikó; Ruat, Marie; Grandl, Susanne; Mayr, Doris; Auweter, Sigrid; Mittone, Alberto; Brun, Emmanuel; Ponchut, Cyril; Reiser, Maximilian F.; Coan, Paola; Olivo, Alessandro

    2016-12-01

    Since the breast is one of the most radiosensitive organs, mammography is arguably the area where lowering radiation dose is of the uttermost importance. Phase-based x-ray imaging methods can provide opportunities in this sense, since they do not require x-rays to be stopped in tissue for image contrast to be generated. Therefore, x-ray energy can be considerably increased compared to those usually exploited by conventional mammography. In this article we show how a novel, optimized approach can lead to considerable dose reductions. This was achieved by matching the edge-illumination phase method, which reaches very high angular sensitivity also at high x-ray energies, to an appropriate image processing algorithm and to a virtually noise-free detection technology capable of reaching almost 100% efficiency at the same energies. Importantly, while proof-of-concept was obtained at a synchrotron, the method has potential for a translation to conventional sources.

  8. A real-time regional adaptive exposure method for saving dose-area product in x-ray fluoroscopy

    SciTech Connect

    Burion, Steve; Funk, Tobias; Speidel, Michael A.

    2013-05-15

    Purpose: Reduction of radiation dose in x-ray imaging has been recognized as a high priority in the medical community. Here the authors show that a regional adaptive exposure method can reduce dose-area product (DAP) in x-ray fluoroscopy. The authors' method is particularly geared toward providing dose savings for the pediatric population. Methods: The scanning beam digital x-ray system uses a large-area x-ray source with 8000 focal spots in combination with a small photon-counting detector. An imaging frame is obtained by acquiring and reconstructing up to 8000 detector images, each viewing only a small portion of the patient. Regional adaptive exposure was implemented by varying the exposure of the detector images depending on the local opacity of the object. A family of phantoms ranging in size from infant to obese adult was imaged in anteroposterior view with and without adaptive exposure. The DAP delivered to each phantom was measured in each case, and noise performance was compared by generating noise arrays to represent regional noise in the images. These noise arrays were generated by dividing the image into regions of about 6 mm{sup 2}, calculating the relative noise in each region, and placing the relative noise value of each region in a one-dimensional array (noise array) sorted from highest to lowest. Dose-area product savings were calculated as the difference between the ratio of DAP with adaptive exposure to DAP without adaptive exposure. The authors modified this value by a correction factor that matches the noise arrays where relative noise is the highest to report a final dose-area product savings. Results: The average dose-area product saving across the phantom family was (42 {+-} 8)% with the highest dose-area product saving in the child-sized phantom (50%) and the lowest in the phantom mimicking an obese adult (23%). Conclusions: Phantom measurements indicate that a regional adaptive exposure method can produce large DAP savings without

  9. Effect of method of heterogenization of ephedrine and reaction conditions on the enantioselectivity of Michael additions

    SciTech Connect

    Krotov, V.V.; Staroverov, S.M.; Nesterenko, P.N.; Lisichkin. G.V.

    1987-11-10

    A series of heterogeneous catalysts for asymmetric Michael additions was synthesized based on ephedrine chemically bound to the surface of silica. The length of the hydrocarbon chain binding the active center to the support surface affects the sign of rotation of the reaction product from the asymmetric addition of thiophenol to benzylideneacetophenone. Grafting ephedrine to the silica surface via a short hydrocarbon chain results in a change in the configuration of the reaction product. Silanol groups on the silica surface are involved in the transition state, as evidenced by data obtained using silica which has been exhaustively treated with trimethylchlorosilane. The absolute specific rotation of 1,3-diphenyl-3-thiophenylpropan-1-one has been established.

  10. Field Method for Detection of Metal Deactivator Additive in Jet Fuel

    DTIC Science & Technology

    2009-04-01

    sulphonic acid on the silica support. The SCX stationary phase is a silica gel with propylbenzenesulfonyl groups bound to the silica, Figure 6. S O O O...They can be grouped into three main categories based on the property of the additive they are detecting. The categories are the; a. Dispersant...was less prominent when lower concentrations of MDA were used. The elution properties of the copper and nickel MDA complexes was examined in a range

  11. An estimate by two methods of thyroid absorbed doses due to BRAVO fallout in several northern Marshall Islands

    SciTech Connect

    Musolino, S.V.; Hull, A.P.; Greenhouse, N.A.

    1997-10-01

    Estimates of the thyroid absorbed doses due to fallout originating from the 1 March 1954 BRAVO thermonuclear test on Bikini Atoll have been made for several inhabited locations in the Northern Marshall Islands. Rongelap, Utirik, Rongerik and Ailinginae Atolls were also inhabited on 1 March 1954, where retrospective thyroid absorbed doses have previously been reconstructed. Current estimates are based primarily on external exposure data, which were recorded shortly after each nuclear test in the Castle Series, and secondarily on soil concentrations of {sup 137}Cs in samples collected in 1978 and 1988, along with aerial monitoring done in 1978. External exposures and {sup 137}Cs Soil concentrations were representative of the atmospheric transport and deposition patterns of the entire Castle Series tests and show that the BRAVO test was the major contributor to fallout exposure during the Castle series and other test series which were carried out in the Marshall Islands. These data have been used as surrogates for fission product radioiodines and telluriums in order to estimate the range of thyroid absorbed doses that may have occurred throughout the Marshall Islands. Dosimetry based on these two sets of estimates agreed within a factor of 4 at the locations where BRAVO was the dominant contributor to the total exposure and deposition. Both methods indicate that thyroid absorbed doses in the range of 1 Gy (100 rad) may have been incurred in some of the northern locations, whereas the doses at southern locations did not significantly exceed levels comparable to those from worldwide fallout. The results of these estimates indicate that a systematic medical survey for thyroid disease should be conducted, and that a more definitive dose reconstruction should be made for all the populated atolls and islands in the Northern Marshall Islands beyond Rongelap, Utirik, Rongerik and Ailinginae, which were significantly contaminated by BRAVO fallout. 30 refs., 2 figs., 10 tabs.

  12. An estimate by two methods of thyroid absorbed doses due to BRAVO fallout in several Northern Marshall Islands.

    PubMed

    Musolino, S V; Greenhouse, N A; Hull, A P

    1997-10-01

    Estimates of the thyroid absorbed doses due to fallout originating from the 1 March 1954 BRAVO thermonuclear test on Bikini Atoll have been made for several inhabited locations in the Northern Marshall Islands. Rongelap, Utirik, Rongerik and Ailinginae Atolls were also inhabited on 1 March 1954, where retrospective thyroid absorbed doses have previously been reconstructed. The current estimates are based primarily on external exposure data, which were recorded shortly after each nuclear test in the Castle Series, and secondarily on soil concentrations of 137Cs in samples collected in 1978 and 1988, along with aerial monitoring done in 1978. The external exposures and 137Cs soil concentrations were representative of the atmospheric transport and deposition patterns of the entire Castle Series tests and show that the BRAVO test was the major contributor to fallout exposure during the Castle series and other test series which were carried out in the Marshall Islands. These data have been used as surrogates for fission product radioiodines and telluriums in order to estimate the range of thyroid absorbed doses that may have occurred throughout the Marshall Islands. Dosimetry based on these two sets of estimates agreed within a factor of 4 at the locations where BRAVO was the dominant contributor to the total exposure and deposition. Both methods indicate that thyroid absorbed doses in the range of 1 Gy (100 rad) may have been incurred in some of the northern locations, whereas the doses at southern locations did not significantly exceed levels comparable to those from worldwide fallout. The results of these estimates indicate that a systematic medical survey for thyroid disease should be conducted, and that a more definitive dose reconstruction should be made for all the populated atolls and islands in the Northern Marshall Islands beyond Rongelap, Utirik, Rongerik and Ailinginae, which were significantly contaminated by BRAVO fallout.

  13. Recommended environmental dose calculation methods and Hanford-specific parameters. Revision 2

    SciTech Connect

    Schreckhise, R.G.; Rhoads, K.; Napier, B.A.; Ramsdell, J.V.; Davis, J.S.

    1993-03-01

    This document was developed to support the Hanford Environmental Dose overview Panel (HEDOP). The Panel is responsible for reviewing all assessments of potential doses received by humans and other biota resulting from the actual or possible environmental releases of radioactive and other hazardous materials from facilities and/or operations belonging to the US Department of Energy on the Hanford Site in south-central Washington. This document serves as a guide to be used for developing estimates of potential radiation doses, or other measures of risk or health impacts, to people and other biota in the environs on and around the Hanford Site. It provides information to develop technically sound estimates of exposure (i.e., potential or actual) to humans or other biotic receptors that could result from the environmental transport of potentially harmful materials that have been, or could be, released from Hanford operations or facilities. Parameter values and information that are specific to the Hanford environs as well as other supporting material are included in this document.

  14. A conservative method of testing whether combination analgesics produce additive or synergistic effects using evidence from acute pain and migraine.

    PubMed

    Moore, R A; Derry, C J; Derry, S; Straube, S; McQuay, H J

    2012-04-01

    Fixed-dose combination analgesics are used widely, and available both on prescription and over-the-counter. Combination drugs should provide more analgesia than with any single drug in the combination, but there is no evidence in humans about whether oral combinations have just additive effects, or are synergistic or even subadditive. We suggest that the measured result for the combination would be the summation of the absolute benefit increase (effect of active drug minus effect of placebo) of each component of a combination if effects were (merely) additive, and greater than the sum of the absolute benefits if they were synergistic. We tested measured effects of combination analgesics against the sum of the absolute benefits in acute pain and migraine using meta-analysis where individual components and combinations were tested against placebo in the same trials, and verified the result with meta-analyses where individual components and combinations were tested against placebo in different trials. Results showed that expected numbers needed to treat (NNT) for additive effects were generally within the 95% confidence interval of measured NNTs. This was true for combinations of paracetamol plus ibuprofen and paracetamol plus opioids in acute pain, and naproxen plus sumatriptan in migraine, but not where efficacy was very low or very high, nor combinations of paracetamol plus dextropropoxyphene. There was no evidence of synergy, defined as supra-additive effects.

  15. Dose banding as an alternative to body surface area-based dosing of chemotherapeutic agents

    PubMed Central

    Chatelut, E; White-Koning, M L; Mathijssen, R HJ; Puisset, F; Baker, S D; Sparreboom, A

    2012-01-01

    Background: Dose banding is a recently suggested dosing method that uses predefined ranges (bands) of body surface area (BSA) to calculate each patient's dose by using a single BSA-value per band. Thus, drugs with sufficient long-term stability can be prepared in advance. The main advantages of dose banding are to reduce patient waiting time and improve pharmacy capacity planning; additional benefits include reduced medication errors, reduced drug wastage, and prospective quality control. This study compares dose banding with individual BSA dosing and fixed dose according to pharmacokinetic criteria. Methods: Three BSA bands were defined: BSA<1.7 m2, 1.7 m2⩽BSA<1.9 m2, BSA⩾1.9 m2 and each patient dose was calculated based on a unique BSA-value per band (1.55, 1.80, and 2.05 m2, respectively). By using individual clearance values of six drugs (cisplatin, docetaxel, paclitaxel, doxorubicin, irinotecan, and topotecan) from 1012 adult cancer patients in total, the AUCs corresponding to three dosing methods (BSA dosing, dose banding, and fixed dose) were compared with a target AUC for each drug. Results: For all six drugs, the per cent variation in individual dose obtained with dose banding compared with BSA dosing ranged between −14% and +22%, and distribution of AUC values was very similar with both dosing methods. In terms of reaching the target AUC, there was no significant difference in precision between dose banding and BSA dosing, except for paclitaxel (32.0% vs 30.7%, respectively; P<0.05). However, precision was significantly better for BSA dosing compared with fixed dose for four out of six drugs. Conclusion: For the studied drugs, implementation of dose banding should be considered as it entails no significant increase in interindividual plasma exposure. PMID:22929884

  16. Efficient method for computing the maximum-likelihood quantum state from measurements with additive Gaussian noise.

    PubMed

    Smolin, John A; Gambetta, Jay M; Smith, Graeme

    2012-02-17

    We provide an efficient method for computing the maximum-likelihood mixed quantum state (with density matrix ρ) given a set of measurement outcomes in a complete orthonormal operator basis subject to Gaussian noise. Our method works by first changing basis yielding a candidate density matrix μ which may have nonphysical (negative) eigenvalues, and then finding the nearest physical state under the 2-norm. Our algorithm takes at worst O(d(4)) for the basis change plus O(d(3)) for finding ρ where d is the dimension of the quantum state. In the special case where the measurement basis is strings of Pauli operators, the basis change takes only O(d(3)) as well. The workhorse of the algorithm is a new linear-time method for finding the closest probability distribution (in Euclidean distance) to a set of real numbers summing to one.

  17. Effects of Al additives on growth of GaN polycrystals by the Na flux method

    NASA Astrophysics Data System (ADS)

    Imabayashi, Hiroki; Murakami, Kosuke; Matsuo, Daisuke; Honjo, Masatomo; Imanishi, Masayuki; Maruyama, Mihoko; Imade, Mamoru; Yoshimura, Masashi; Mori, Yusuke

    2017-03-01

    In this study, we investigated the growth of GaN polycrystals using the Al-added Na flux method. We studied the effects of Al on accelerating the nucleation and purity of GaN polycrystals. The yields of GaN crystals grown in Al-added Na flux were dramatically increased from those in Al-free Na flux, and the polycrystals grown by the Al-added Na flux method were highly transparent. As observed in secondary ion mass spectroscopy measurements, the Al content of the polycrystals was below the detection limit of 3 × 1016 atoms/cm3. From these results, the Al-added Na flux method is found to be appropriate for fabricating a large amount of GaN polycrystals without deteriorating the crystal quality.

  18. Assessment of ambient gamma dose rate around a prospective uranium mining area of South India - A comparative study of dose by direct methods and soil radioactivity measurements

    NASA Astrophysics Data System (ADS)

    Karunakara, N.; Yashodhara, I.; Sudeep Kumara, K.; Tripathi, R. M.; Menon, S. N.; Kadam, S.; Chougaonkar, M. P.

    Indoor and outdoor gamma dose rates were evaluated around a prospective uranium mining region - Gogi, South India through (i) direct measurements using a GM based gamma dose survey meter, (ii) integrated measurement days using CaSO4:Dy based thermo luminescent dosimeters (TLDs), and (iii) analyses of 273 soil samples for 226Ra, 232Th, and 40K activity concentration using HPGe gamma spectrometry. The geometric mean values of indoor and outdoor gamma dose rates were 104 nGy h-1 and 97 nGy h-1, respectively with an indoor to outdoor dose ratio of 1.09. The gamma dose rates and activity concentrations of 226Ra, 232Th, and 40K varied significantly within a small area due to the highly localized mineralization of the elements. Correlation study showed that the dose estimated from the soil radioactivity is better correlated with that measured directly using the portable survey meter, when compared to that obtained from TLDs. This study showed that in a region having localized mineralization in situ measurements using dose survey meter provide better representative values of gamma dose rates.

  19. A general method to derive tissue parameters for Monte Carlo dose calculation with multi-energy CT.

    PubMed

    Lalonde, Arthur; Bouchard, Hugo

    2016-11-21

    To develop a general method for human tissue characterization with dual- and multi-energy CT and evaluate its performance in determining elemental compositions and quantities relevant to radiotherapy Monte Carlo dose calculation. Ideal materials to describe human tissue are obtained applying principal component analysis on elemental weight and density data available in literature. The theory is adapted to elemental composition for solving tissue information from CT data. A novel stoichiometric calibration method is integrated to the technique to make it suitable for a clinical environment. The performance of the method is compared with two techniques known in literature using theoretical CT data. In determining elemental weights with dual-energy CT, the method is shown to be systematically superior to the water-lipid-protein material decomposition and comparable to the parameterization technique. In determining proton stopping powers and energy absorption coefficients with dual-energy CT, the method generally shows better accuracy and unbiased results. The generality of the method is demonstrated simulating multi-energy CT data to show the potential to extract more information with multiple energies. The method proposed in this paper shows good performance to determine elemental compositions from dual-energy CT data and physical quantities relevant to radiotherapy dose calculation. The method is particularly suitable for Monte Carlo calculations and shows promise in using more than two energies to characterize human tissue with CT.

  20. 76 FR 76035 - Amendment to the International Traffic in Arms Regulations: Additional Method of Electronic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-06

    ...Wire), or Society for Worldwide Interbank Financial Telecommunications (SWIFT), payable to the... United States and SWIFT is the messaging service used by financial institutions worldwide to issue international transfers for foreign accounts. Payment methods (i.e., ACH, FedWire, and SWIFT) are dependent...

  1. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, Robert A.; Snowden-Swan, Lesley J.

    1997-01-01

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber.

  2. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, R.A.; Snowden-Swan, L.J.

    1997-01-28

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber. 8 figs.

  3. Investigating Arsenic Contents in Surface and Drinking Water by Voltammetry and the Method of Standard Additions

    ERIC Educational Resources Information Center

    Cheng, Anran; Tyne, Rebecca; Kwok, Yu Ting; Rees, Louis; Craig, Lorraine; Lapinee, Chaipat; D'Arcy, Mitch; Weiss, Dominik J.; Salau¨n, Pascal

    2016-01-01

    Testing water samples for arsenic contamination has become an important water quality issue worldwide. Arsenic usually occurs in very small concentrations, and a sensitive analytical method is needed. We present here a 1-day laboratory module developed to introduce Earth Sciences and/or Chemistry student undergraduates to key aspects of this…

  4. Investigation of the gold nanoparticles effects on the prostate dose distribution in brachytherapy: gel dosimetry and Monte Carlo method

    PubMed Central

    Hashemi, Bijan; Rahmani, Faezeh; Ebadi, Ahmad

    2016-01-01

    Purpose In this work, gold nanoparticles (GNPs) were embedded in the MAGIC-f polymer gel irradiated with the 192Ir brachytherapy sources. Material and methods At the first plexiglas phantom was made as the human pelvis. The GNPs were synthesized with 15 nm in diameter and 0.1 mM (0.0197 mg/ml) in concentration by using a chemical reduction method. Then, the MAGIC-f gel was synthesized. The fabricated gel was poured into the tubes located at the prostate (with and without the GNPs) locations of the phantom. The phantom was irradiated with 192Ir brachytherapy sources for prostate cancer. After 24 hours, the irradiated gels was read by using Siemens 1.5 Tesla MRI scanner. Following the brachytherapy practices, the absolute doses at the reference points and isodose curves were extracted and compared by experimental measurements and Monte Carlo (MC) simulations. Results The mean absorbed doses in the presence of the GNPs in prostate were 14% higher than the corresponding values without the GNPs in the brachytherapy. The gamma index analysis (between gel and MC) using 7%/7 mm was also applied to the data and a high pass rate achieved (91.7% and 86.4% for analysis with/without GNPs, respectively). Conclusions The real three-dimensional analysis shows the comparison of the dose-volume histograms measured for planning volumes and the expected one from the MC calculation. The results indicate that the polymer gel dosimetry method, which developed and used in this study, could be recommended as a reliable method for investigating the dose enhancement factor of GNPs in brachytherapy. PMID:27895684

  5. Evaluation of SHM System Produced by Additive Manufacturing via Acoustic Emission and Other NDT Methods

    PubMed Central

    Strantza, Maria; Aggelis, Dimitrios G.; de Baere, Dieter; Guillaume, Patrick; van Hemelrijck, Danny

    2015-01-01

    During the last decades, structural health monitoring (SHM) systems are used in order to detect damage in structures. We have developed a novel structural health monitoring approach, the so-called “effective structural health monitoring” (eSHM) system. The current SHM system is incorporated into a metallic structure by means of additive manufacturing (AM) and has the possibility to advance life safety and reduce direct operative costs. It operates based on a network of capillaries that are integrated into an AM structure. The internal pressure of the capillaries is continuously monitored by a pressure sensor. When a crack nucleates and reaches the capillary, the internal pressure changes signifying the existence of the flaw. The main objective of this paper is to evaluate the crack detection capacity of the eSHM system and crack location accuracy by means of various non-destructive testing (NDT) techniques. During this study, detailed acoustic emission (AE) analysis was applied in AM materials for the first time in order to investigate if phenomena like the Kaiser effect and waveform parameters used in conventional metals can offer valuable insight into the damage accumulation of the AM structure as well. Liquid penetrant inspection, eddy current and radiography were also used in order to confirm the fatigue damage and indicate the damage location on un-notched four-point bending AM metallic specimens with an integrated eSHM system. It is shown that the eSHM system in combination with NDT can provide correct information on the damage condition of additive manufactured metals. PMID:26506349

  6. Evaluation of SHM system produced by additive manufacturing via acoustic emission and other NDT methods.

    PubMed

    Strantza, Maria; Aggelis, Dimitrios G; de Baere, Dieter; Guillaume, Patrick; van Hemelrijck, Danny

    2015-10-21

    During the last decades, structural health monitoring (SHM) systems are used in order to detect damage in structures. We have developed a novel structural health monitoring approach, the so-called "effective structural health monitoring" (eSHM) system. The current SHM system is incorporated into a metallic structure by means of additive manufacturing (AM) and has the possibility to advance life safety and reduce direct operative costs. It operates based on a network of capillaries that are integrated into an AM structure. The internal pressure of the capillaries is continuously monitored by a pressure sensor. When a crack nucleates and reaches the capillary, the internal pressure changes signifying the existence of the flaw. The main objective of this paper is to evaluate the crack detection capacity of the eSHM system and crack location accuracy by means of various non-destructive testing (NDT) techniques. During this study, detailed acoustic emission (AE) analysis was applied in AM materials for the first time in order to investigate if phenomena like the Kaiser effect and waveform parameters used in conventional metals can offer valuable insight into the damage accumulation of the AM structure as well. Liquid penetrant inspection, eddy current and radiography were also used in order to confirm the fatigue damage and indicate the damage location on un-notched four-point bending AM metallic specimens with an integrated eSHM system. It is shown that the eSHM system in combination with NDT can provide correct information on the damage condition of additive manufactured metals.

  7. A Method to Evaluate Additional Waste Forms to Optimize Performance of the HLW Repository

    SciTech Connect

    D. Gombert; L. Lauerhass

    2006-02-01

    The DOE high-level waste (HLW) disposal system is based on decisions made in the 1970s. The de facto Yucca Mountain WAC for HLW, contained in the Waste Acceptance System Requirements Document (WASRD), and the DOE-EM Waste Acceptance Product Specification for Vitrified High Level Waste Forms (WAPS) tentatively describes waste forms to be interred in the repository, and limits them to borosilicate glass (BSG). It is known that many developed waste forms are as durable as or better than environmental assessment or “EA”-glass. Among them are the salt-ceramic and metallic waste forms developed at ANL-W. Also, iron phosphate glasses developed at University of Missouri show promise in stabilizing the most refractory materials in Hanford HLW. However, for any of this science to contribute, the current Total System Performance Assessment model must be able to evaluate the additional waste form to determine potential impacts on repository performance. The results can then support the technical bases required in the repository license application. A methodology is proposed to use existing analysis models to evaluate potential additional waste forms for disposal without gathering costly material specific degradation data. The concept is to analyze the potential impacts of waste form chemical makeup on repository performance assuming instantaneous waste matrix dissolution. This assumption obviates the need for material specific degradation models and is based on the relatively modest fractional contribution DOE HLW makes to the repository radionuclide and hazardous metals inventory. The existing analysis models, with appropriate data modifications, are used to evaluate geochemical interactions and material transport through the repository. This methodology would support early screening of proposed waste forms through simplified evaluation of disposal performance, and would provide preliminary guidance for repository license amendment in the future.

  8. Method for characterizing the coking tendencies of baseoils and additive-treated oils

    SciTech Connect

    Dickakian, G.B.

    1989-07-18

    This patent describes a method of characterizing the coking tendency of baseoil. The method consists the steps of: (a) subjecting the baseoil to conditions which accelerate asphaltene coke precursor formation in the baseoil, and (b) characterizing the coking tendency of the baseoil by determining (i) the onset and progression of asphaltene coke precursor formation as a function of time or (ii) the progression of asphaltene coke precursor formation as a function of time, wherein a faster onset of asphaltene coke precursor formation and a higher rate of asphaltene coke precursor formation or a higher rate of asphaltene coke precursor formation indicates a higher coking tendency of the baseoil than a slower onset of asphaltene coke precursor formation and a lower rate of asphaltene coke precursor formation or a lower rate of asphaltene coke precursor formation.

  9. [High Throughput Screening Analysis of Preservatives and Sweeteners in Carbonated Beverages Based on Improved Standard Addition Method].

    PubMed

    Wang, Su-fang; Liu, Yun; Gong, Li-hua; Dong, Chun-hong; Fu, De-xue; Wang, Guo-qing

    2016-02-01

    Simulated water samples of 3 kinds of preservatives and 4 kinds of sweeteners were formulated by using orthogonal design. Kernel independent component analysis (KICA) was used to process the UV spectra of the simulated water samples and the beverages added different amounts of the additive standards, then the independent components (ICs), i. e. the UV spectral profiles of the additives, and the ICs' coefficient matrices were used to establish UV-KICA-SVR prediction model of the simulated preservatives and sweeteners solutions using support vector regression (SVR) analysis. The standards added beverages samples were obtained by adding different amounts level of additives in carbonated beverages, their UV spectra were processed by KICA, then IC information represented to the additives and other sample matrix were obtained, and the sample background can be deducted by removing the corresponding IC, other ICs' coefficient matrices were used to estimate the amounts of the additives in the standard added beverage samples based on the UV-KICA-SVR model, while the intercept of linear regression equation of predicted amounts and the added amounts in the standard added samples is the additive content in the raw beverage sample. By utilization of chemometric "blind source separation" method for extracting IC information of the tested additives in the beverage and other sample matrix, and using SVR regression modeling to improve the traditional standard addition method, a new method was proposed for the screening of the preservatives and sweeteners in carbonated beverages. The proposed UV-KICA-SVR method can be used to determine 3 kinds of preservatives and 4 kinds of sweetener in the carbonate beverages with the limit of detection (LOD) are located with the range 0.2-1.0 mg · L⁻¹, which are comparable to that of the traditional high performance liquid chromatographic (HPLC) method.

  10. Solution of Some Additional Electromagnetic Problems by the Discrete Convolution Method

    DTIC Science & Technology

    1984-02-01

    dimensional DCM . However, it cannot be solved using the block Toeplitz method since the field on the phantom Table I. Results for some helical...It is apparent from the discussions of other one dimensional problems that both problems can be solved using the one dimensional DCM technique. For...the helix with gaps all we need is to insert phantom elements as shown in Fig. 2. Table 1 gives the number of iterations needed to get the required

  11. Comparison of dose estimates using the buildup-factor method and a Baryon transport code (BRYNTRN) with Monte Carlo results

    NASA Technical Reports Server (NTRS)

    Shinn, Judy L.; Wilson, John W.; Nealy, John E.; Cucinotta, Francis A.

    1990-01-01

    Continuing efforts toward validating the buildup factor method and the BRYNTRN code, which use the deterministic approach in solving radiation transport problems and are the candidate engineering tools in space radiation shielding analyses, are presented. A simplified theory of proton buildup factors assuming no neutron coupling is derived to verify a previously chosen form for parameterizing the dose conversion factor that includes the secondary particle buildup effect. Estimates of dose in tissue made by the two deterministic approaches and the Monte Carlo method are intercompared for cases with various thicknesses of shields and various types of proton spectra. The results are found to be in reasonable agreement but with some overestimation by the buildup factor method when the effect of neutron production in the shield is significant. Future improvement to include neutron coupling in the buildup factor theory is suggested to alleviate this shortcoming. Impressive agreement for individual components of doses, such as those from the secondaries and heavy particle recoils, are obtained between BRYNTRN and Monte Carlo results.

  12. Application of the two-dose-rate method for general recombination correction for liquid ionization chambers in continuous beams

    NASA Astrophysics Data System (ADS)

    Andersson, Jonas; Tölli, Heikki

    2011-01-01

    A method to correct for the general recombination losses for liquid ionization chambers in continuous beams has been developed. The proposed method has been derived from Greening's theory for continuous beams and is based on measuring the signal from a liquid ionization chamber and an air filled monitor ionization chamber at two different dose rates. The method has been tested with two plane parallel liquid ionization chambers in a continuous radiation x-ray beam with a tube voltage of 120 kV and with dose rates between 2 and 13 Gy min-1. The liquids used as sensitive media in the chambers were isooctane (C8H18) and tetramethylsilane (Si(CH3)4). The general recombination effect was studied using chamber polarizing voltages of 100, 300, 500, 700 and 900 V for both liquids. The relative standard deviation of the results for the collection efficiency with respect to general recombination was found to be a maximum of 0.7% for isooctane and 2.4% for tetramethylsilane. The results are in excellent agreement with Greening's theory for collection efficiencies over 90%. The measured and corrected signals from the liquid ionization chambers used in this work are in very good agreement with the air filled monitor chamber with respect to signal to dose linearity.

  13. Application of the two-dose-rate method for general recombination correction for liquid ionization chambers in continuous beams.

    PubMed

    Andersson, Jonas; Tölli, Heikki

    2011-01-21

    A method to correct for the general recombination losses for liquid ionization chambers in continuous beams has been developed. The proposed method has been derived from Greening's theory for continuous beams and is based on measuring the signal from a liquid ionization chamber and an air filled monitor ionization chamber at two different dose rates. The method has been tested with two plane parallel liquid ionization chambers in a continuous radiation x-ray beam with a tube voltage of 120 kV and with dose rates between 2 and 13 Gy min(-1). The liquids used as sensitive media in the chambers were isooctane (C(8)H(18)) and tetramethylsilane (Si(CH(3))(4)). The general recombination effect was studied using chamber polarizing voltages of 100, 300, 500, 700 and 900 V for both liquids. The relative standard deviation of the results for the collection efficiency with respect to general recombination was found to be a maximum of 0.7% for isooctane and 2.4% for tetramethylsilane. The results are in excellent agreement with Greening's theory for collection efficiencies over 90%. The measured and corrected signals from the liquid ionization chambers used in this work are in very good agreement with the air filled monitor chamber with respect to signal to dose linearity.

  14. A New Method for Finding Optical Aberrations on the Basis of Analysis of the Object Hologram Without Additional Measurements

    NASA Astrophysics Data System (ADS)

    Matkivsky, V. A.; Moiseev, A. A.; Shilyagin, P. A.; Shabanov, D. V.; Gelikonov, G. V.; Gelikonov, V. M.

    2016-11-01

    We propose a new method of compensating for the wavefront aberrations during the image processing. The method employs the digital-holography potential. The developed algorithms allow one to find the wavefront distortions caused by the optical-path nonuniformities during the interference recording of images without additional measurements (i.e., without using the reference point source and measuring the wavefront distortions). The possibility of decreasing the wavefront aberrations from tens to several radians using digital methods is demonstrated.

  15. Estimation of the total rectal dose of radical external beam and intracavitary radiotherapy for uterine cervical cancer using the deformable image registration method

    PubMed Central

    Hayashi, Kazuhiko; Isohashi, Fumiaki; Akino, Yuichi; Wakai, Nobuhide; Mabuchi, Seiji; Suzuki, Osamu; Seo, Yuji; Ootani, Yuki; Sumida, Iori; Yoshioka, Yasuo; Kimura, Tadashi; Ogawa, Kazuhiko

    2015-01-01

    We adapted the deformable image registration (DIR) technique to accurately calculate the cumulative intracavitary brachytherapy (ICBT) and external beam radiotherapy (EBRT) rectal dose for treating uterine cervical cancer. A total of 14 patients with primary cervical cancer radically treated with ICRT and EBRT were analysed using the Velocity AITM software. Computed tomography (CT) images were registered, and EBRT and ICBT dose distributions were determined. Cumulative D2cm3, D1cm3 and D0.1cm3 were calculated by simple addition of fractional values or by DIR. The accuracy of DIR was evaluated by means of a virtual phantom mimicking the rectum. The dice similarity coefficient (DSC) was calculated to evaluate rectal contour concordance between CT images before and after DIR. Virtual phantom analysis revealed that the average difference between the DIR-based phantom Dmean and the simple phantom Dmean was 1.9 ± 2.5 Gy (EQD2), and the DIR method included an uncertainty of ∼8.0%. The mean DSC between reference CT and CT was significantly improved after DIR (EBRT: 0.43 vs 0.85, P < 0.005; ICBT: 0.60 vs 0.87, P < 0.005). The average simple rectal D2cm3, D1cm3 and D0.1cm3 values were 77.6, 81.6 and 91.1 Gy (EQD2), respectively; the DIR-based values were 76.2, 79.5 and 87.6 Gy, respectively. The simple addition values were overestimated, on average, by 3.1, 3.7 and 5.5 Gy, respectively, relative to the DIR-based values. In conclusion, the difference between the simple rectal dose–volume histogram (DVH) parameter addition and DIR-based cumulative rectal doses increased with decreasing DVH parameters. PMID:25678538

  16. Methods For Calculating Thyroid Doses to The Residents Of Ozersk Due to 131I Releases From The Stacks of The Mayak Production Association

    SciTech Connect

    Rovny, Sergey I.; Mokrov, Y.; Stukalov, Pavel M.; Beregich, D. A.; Teplyakov, I. I.; Anspaugh, L. R.; Napier, Bruce A.

    2009-10-23

    The Mayak Production Association (MPA) was established in the late 1940s in accordance with a special Decree of the USSR Government for the production of nuclear weapons. In early years of MPA operation, due to the lack of experience and absence of effective methods of RW management, the enterprise had extensive routine (designed) and non-routine (accidental) releases of gaseous radioactive wastes to the atmosphere. These practices resulted in additional technogenic radiation exposure of residents inhabiting populated areas near the MPA. The primary objective of ongoing studies under JCCRER Project 1.4 is to estimate doses to the residents of Ozersk due to releases of radioactive substances from the stacks of MPA. Preliminary scoping studies have demonstrated that releases of radioactive iodine (131I) from the stacks of the Mayak Radiochemical Plant represented the major contribution to the dose to residents of Ozersk and of other nearby populated areas. The behavior of 131I in the environment and of 131I migration through biological food chains (vegetation-cows-milk-humans) indicated a need for use of special mathematical models to perform the estimation of radiation doses to the population. The goal of this work is to select an appropriate model of the iodine migration in biological food chains and to justify numerical values of the model parameters.

  17. Investigation in the use of plasma arc welding and alternative feedstock delivery method in additive manufacture

    NASA Astrophysics Data System (ADS)

    Alhuzaim, Abdullah F.

    The work conducted for this thesis was to investigate the use of plasma arc welding (PAW) and steel shot as a means of additive manufacturing. A robotic PAW system and automatic shot feeder were used to manufacture linear walls approximately 100 mm long by 7 mm wide and 20 mm tall. The walls were built, layer-by-layer, on plain carbon steel substrate by adding individual 2.5 mm diameter plain carbon steel shot. Each layer was built, shot-by-shot, using a pulse of arc current to form a molten pool on the deposit into which each shot was deposited and melted. The deposition rate, a measure of productivity, was approximately 50 g/hour. Three walls were built using the same conditions except for the deposit preheat temperature prior to adding each new layer. The deposit preheat temperature was controlled by allowing the deposit to cool after each layer for an amount of time called the inter-layer wait time. The walls were sectioned and grain size and hardness distribution were measured as a function of wall height. The results indicated that, for all specimens, deposit grain size increased and hardness decreased as wall height increased. Furthermore, average grain size decreased and hardness increased as interlayer wait time increased. An analytical heat flow model was developed to study the influence of interlayer wait time on deposit temperature and therefore grain size and hardness. The results of the model indicated that as wall height increased, the rate of deposit heat removal by conduction to the substrate decreased leading to a higher preheat temperature after a fixed interlayer wait time causing grain size to increase as wall height increased. However, the model results also show that as wall height increased, the deposit surface area from which heat energy is lost via convection and radiation increased. The model also demonstrated that the use of a means of forced convection to rapidly remove heat from the deposit could be an effective way to boost

  18. A numerical method to optimise the spatial dose distribution in carbon ion radiotherapy planning.

    PubMed

    Grzanka, L; Korcyl, M; Olko, P; Waligorski, M P R

    2015-09-01

    The authors describe a numerical algorithm to optimise the entrance spectra of a composition of pristine carbon ion beams which delivers a pre-assumed dose-depth profile over a given depth range within the spread-out Bragg peak. The physical beam transport model is based on tabularised data generated using the SHIELD-HIT10A Monte-Carlo code. Depth-dose profile optimisation is achieved by minimising the deviation from the pre-assumed profile evaluated on a regular grid of points over a given depth range. This multi-dimensional minimisation problem is solved using the L-BFGS-B algorithm, with parallel processing support. Another multi-dimensional interpolation algorithm is used to calculate at given beam depths the cumulative energy-fluence spectra for primary and secondary ions in the optimised beam composition. Knowledge of such energy-fluence spectra for each ion is required by the mixed-field calculation of Katz's cellular Track Structure Theory (TST) that predicts the resulting depth-survival profile. The optimisation algorithm and the TST mixed-field calculation are essential tools in the development of a one-dimensional kernel of a carbon ion therapy planning system. All codes used in the work are generally accessible within the libamtrack open source platform.

  19. Population Pharmacokinetics of Tenofovir in HIV-1-Uninfected Members of Serodiscordant Couples and Effect of Dose Reporting Methods

    PubMed Central

    Lu, Yanhui; Goti, Vineet; Haberer, Jessica E.; Fossler, Michael J.; Sale, Mark E.; Bangsberg, David; Baeten, Jared M.; Celum, Connie L.; Hendrix, Craig W.

    2016-01-01

    Antiretroviral preexposure prophylaxis (PrEP) with once-daily dosing of tenofovir and tenofovir-emtricitabine was shown to be effective for preventing HIV-1 infection in individuals who had HIV-1-seropositive partners (the Partners PrEP Study). We developed a population pharmacokinetic model for tenofovir and investigated the impacts of different dose reporting methods. Dosing information was collected as patient-reported dosing information (PRDI) from 404 subjects (corresponding to 1,280 drug concentration records) from the main trial and electronic monitoring-based adherence data collected from 211 subjects (corresponding to 327 drug concentration records) in an ancillary adherence study. Model development was conducted with NONMEM (7.2), using PRDI with a steady-state assumption or using PRDI replaced with electronic monitoring records where available. A two-compartment model with first-order absorption was the best model in both modeling approaches, with the need for an absorption lag time when electronic monitoring-based dosing records were included in the analysis. Age, body weight, and creatinine clearance were significant covariates on clearance, but only creatinine clearance was retained in the final models per stepwise selection. Sex was not a significant covariate on clearance. Tenofovir population pharmacokinetic parameter estimates and the precisions of the parameters from the two final models were comparable with the point estimates of the parameters, differing from 0% to 35%, and bootstrap confidence intervals widely overlapped. These findings indicate that PRDI was sufficient for population pharmacokinetic model development in this study, with a high level of adherence per multiple measures. PMID:27353269

  20. A method to correct for temperature dependence and measure simultaneously dose and temperature using a plastic scintillation detector

    PubMed Central

    Therriault-Proulx, Francois; Wootton, Landon; Beddar, Sam

    2015-01-01

    Plastic scintillation detectors (PSDs) work well for radiation dosimetry. However, they show some temperature dependence, and a priori knowledge of the temperature surrounding the PSD is required to correct for this dependence. We present a novel approach to correct PSD response values for temperature changes instantaneously and without the need for prior knowledge of the temperature value. In addition to rendering the detector temperature-independent, this approach allows for actual temperature measurement using solely the PSD apparatus. With a temperature-controlled water tank, the temperature was varied from room temperature to more than 40°C and the PSD was used to measure the dose delivered from a cobalt-60 photon beam unit to within an average of 0.72% from the expected value. The temperature was measured during each acquisition with the PSD and a thermocouple and values were within 1°C of each other. The depth-dose curve of a 6-MV photon beam was also measured under warm non-stable conditions and this curve agreed to within an average of −0.98% from the curve obtained at room temperature. The feasibility of rendering PSDs temperature-independent was demonstrated with our approach, which also enabled simultaneous measurement of both dose and temperature. This novel approach improves both the robustness and versatility of PSDs. PMID:26407188

  1. Hidden drivers of low-dose pharmaceutical pollutant mixtures revealed by the novel GSA-QHTS screening method

    PubMed Central

    Rodea-Palomares, Ismael; Gonzalez-Pleiter, Miguel; Gonzalo, Soledad; Rosal, Roberto; Leganes, Francisco; Sabater, Sergi; Casellas, Maria; Muñoz-Carpena, Rafael; Fernández-Piñas, Francisca

    2016-01-01

    The ecological impacts of emerging pollutants such as pharmaceuticals are not well understood. The lack of experimental approaches for the identification of pollutant effects in realistic settings (that is, low doses, complex mixtures, and variable environmental conditions) supports the widespread perception that these effects are often unpredictable. To address this, we developed a novel screening method (GSA-QHTS) that couples the computational power of global sensitivity analysis (GSA) with the experimental efficiency of quantitative high-throughput screening (QHTS). We present a case study where GSA-QHTS allowed for the identification of the main pharmaceutical pollutants (and their interactions), driving biological effects of low-dose complex mixtures at the microbial population level. The QHTS experiments involved the integrated analysis of nearly 2700 observations from an array of 180 unique low-dose mixtures, representing the most complex and data-rich experimental mixture effect assessment of main pharmaceutical pollutants to date. An ecological scaling-up experiment confirmed that this subset of pollutants also affects typical freshwater microbial community assemblages. Contrary to our expectations and challenging established scientific opinion, the bioactivity of the mixtures was not predicted by the null mixture models, and the main drivers that were identified by GSA-QHTS were overlooked by the current effect assessment scheme. Our results suggest that current chemical effect assessment methods overlook a substantial number of ecologically dangerous chemical pollutants and introduce a new operational framework for their systematic identification. PMID:27617294

  2. Hidden drivers of low-dose pharmaceutical pollutant mixtures revealed by the novel GSA-QHTS screening method.

    PubMed

    Rodea-Palomares, Ismael; Gonzalez-Pleiter, Miguel; Gonzalo, Soledad; Rosal, Roberto; Leganes, Francisco; Sabater, Sergi; Casellas, Maria; Muñoz-Carpena, Rafael; Fernández-Piñas, Francisca

    2016-09-01

    The ecological impacts of emerging pollutants such as pharmaceuticals are not well understood. The lack of experimental approaches for the identification of pollutant effects in realistic settings (that is, low doses, complex mixtures, and variable environmental conditions) supports the widespread perception that these effects are often unpredictable. To address this, we developed a novel screening method (GSA-QHTS) that couples the computational power of global sensitivity analysis (GSA) with the experimental efficiency of quantitative high-throughput screening (QHTS). We present a case study where GSA-QHTS allowed for the identification of the main pharmaceutical pollutants (and their interactions), driving biological effects of low-dose complex mixtures at the microbial population level. The QHTS experiments involved the integrated analysis of nearly 2700 observations from an array of 180 unique low-dose mixtures, representing the most complex and data-rich experimental mixture effect assessment of main pharmaceutical pollutants to date. An ecological scaling-up experiment confirmed that this subset of pollutants also affects typical freshwater microbial community assemblages. Contrary to our expectations and challenging established scientific opinion, the bioactivity of the mixtures was not predicted by the null mixture models, and the main drivers that were identified by GSA-QHTS were overlooked by the current effect assessment scheme. Our results suggest that current chemical effect assessment methods overlook a substantial number of ecologically dangerous chemical pollutants and introduce a new operational framework for their systematic identification.

  3. Features of the Ti-40Nb alloy prototype formation by 3D additive method

    NASA Astrophysics Data System (ADS)

    Sharkeev, Yu. P.; Kovalevskaya, Zh. G.; Khimich, M. A.; Eroshenko, A. Yu.; Saprykin, A. A.; Ibragimov, E. A.; Glukhov, I. A.

    2016-11-01

    The structure of Ti-40Nb alloy prototype obtained by selective laser melting (SLM) on "VARISKAF 100MV" installation was considered by the methods of optical metallography, scanning and transmission electron microscopy. It was revealed that the most of the specimens' surface is uniform flowed surface with typical banded structure formed by laying-on molten pools. The process of the individual layer formation was followed by drop formation. This leads to the porosity formation on the specimen's surface. The structure of entire specimen is not homogeneous throughout the transverse section. The porosity of three kinds is observed. They are cavities of not full contact and melting of the layers, drawholes, gas pores. The porosity optimization requires more careful SLM modes selection. The alloy has a grain structure with anisotropy from small (2-8 µm) to medium (8-20 µm) grain size. The anisotropy of the specimen is formed in each layer and is retained during building of the specimen. The grains of microstructure are formed by the main β-phase with precipitations of nonequilibrium α″-martensite on the boundaries and within the grains.

  4. Estimation of accumulated dose of radiation by the method of ESR-spectrometry of dental enamel of mammals.

    PubMed

    Serezhenkov, V A; Moroz, I A; Klevezal, G A; Vanin, A F

    1996-01-01

    ESR-spectrometry was used to investigate radiation-induced paramagnetic centers in enamel of mammals: carnivores (polar bear and fox), ungulates (reindeer, European bison, moose), and man. Values at half the microwave power saturation of the radiation signal, P1/2, evaluated at room temperature, was found to range from 16 to 26 mW for animals and man. A new approach to discrimination of the radiation induced signal from the total ESR spectrum of reindeer enamel is proposed. 'Dose-response' dependencies of enamel of different species mammals were measured within the dose range from 0.48 up to 10.08 Gy. Estimations of 'radiosensitivity' enamel of carnivores and ungulates showed good agreement with radiosensitivity enamel of man by ESR method.

  5. The Multi-Step CADIS method for shutdown dose rate calculations and uncertainty propagation

    DOE PAGES

    Ibrahim, Ahmad M.; Peplow, Douglas E.; Grove, Robert E.; ...

    2015-12-01

    Shutdown dose rate (SDDR) analysis requires (a) a neutron transport calculation to estimate neutron flux fields, (b) an activation calculation to compute radionuclide inventories and associated photon sources, and (c) a photon transport calculation to estimate final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for very large systems with massive amounts of shielding materials. However, these simulations are impractical because calculation of space- and energy-dependent neutron fluxes throughout the structural materials is needed to estimate distribution of radioisotopes causing the SDDR. Biasing the neutron MC calculation using an importance function is not simple becausemore » it is difficult to explicitly express the response function, which depends on subsequent computational steps. Furthermore, the typical SDDR calculations do not consider how uncertainties in MC neutron calculation impact SDDR uncertainty, even though MC neutron calculation uncertainties usually dominate SDDR uncertainty.« less

  6. The Multi-Step CADIS method for shutdown dose rate calculations and uncertainty propagation

    SciTech Connect

    Ibrahim, Ahmad M.; Peplow, Douglas E.; Grove, Robert E.; Peterson, Joshua L.; Johnson, Seth R.

    2015-12-01

    Shutdown dose rate (SDDR) analysis requires (a) a neutron transport calculation to estimate neutron flux fields, (b) an activation calculation to compute radionuclide inventories and associated photon sources, and (c) a photon transport calculation to estimate final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for very large systems with massive amounts of shielding materials. However, these simulations are impractical because calculation of space- and energy-dependent neutron fluxes throughout the structural materials is needed to estimate distribution of radioisotopes causing the SDDR. Biasing the neutron MC calculation using an importance function is not simple because it is difficult to explicitly express the response function, which depends on subsequent computational steps. Furthermore, the typical SDDR calculations do not consider how uncertainties in MC neutron calculation impact SDDR uncertainty, even though MC neutron calculation uncertainties usually dominate SDDR uncertainty.

  7. An Automated Dosing Method for a HIFU Device Containing Multiple Phased Arrays

    NASA Astrophysics Data System (ADS)

    Zeng, Xiaozheng Jenny; Barnes, Steve; Sekins, K. Michael

    2010-03-01

    A device containing multiple 2D therapeutic and imaging ultrasound phased arrays is proposed for acoustic hemostasis applications. An automated dosing algorithm selects the optimal combination of therapeutic phased arrays and calculates the acoustic power required of each array. Simulations demonstrate that therapeutic temperatures (70° Cdosing times. The spatial-peak-time-averaged intensity in the target focal zone was ≈600 W/cm2, below the inertial cavitation threshold for these conditions. Simulations showed that the proposed ultrasound device yielded a relatively uniform temperature distribution in the target volume.

  8. SU-E-T-561: Development of Depth Dose Measurement Technique Using the Multilayer Ionization Chamber for Spot Scanning Method

    SciTech Connect

    Takayanagi, T; Fujitaka, S; Umezawa, M; Ito, Y; Nakashima, C; Matsuda, K

    2014-06-01

    Purpose: To develop a measurement technique which suppresses the difference between profiles obtained with a multilayer ionization chamber (MLIC) and with a water phantom. Methods: The developed technique multiplies the raw MLIC data by a correction factor that depends on the initial beam range and water equivalent depth. The correction factor is derived based on a Bragg curve calculation formula considering range straggling and fluence loss caused by nuclear reactions. Furthermore, the correction factor is adjusted based on several integrated depth doses measured with a water phantom and the MLIC. The measured depth dose profiles along the central axis of the proton field with a nominal field size of 10 by 10 cm were compared between the MLIC using the new technique and the water phantom. The spread out Bragg peak was 20 cm for fields with a range of 30.6 cm and 6.9 cm. Raw MLIC data were obtained with each energy layer, and integrated after multiplying by the correction factor. The measurements were performed by a spot scanning nozzle at Nagoya Proton Therapy Center, Japan. Results: The profile measured with the MLIC using the new technique is consistent with that of the water phantom. Moreover, 97% of the points passed the 1% dose /1mm distance agreement criterion of the gamma index. Conclusion: We have demonstrated that the new technique suppresses the difference between profiles obtained with the MLIC and with the water phantom. It was concluded that this technique is useful for depth dose measurement in proton spot scanning method.

  9. New investigation of distribution imaging and content uniformity of very low dose drugs using hot-melt extrusion method.

    PubMed

    Park, Jun-Bom; Kang, Chin-Yang; Kang, Wie-Soo; Choi, Han-Gon; Han, Hyo-Kyung; Lee, Beom-Jin

    2013-12-31

    The content uniformity of low dose drugs in dosage forms is very important for quality assurance. The aim of this study was to prepare uniformly and homogeneously distributed dosage forms of very low-dose drugs using twin screw hot-melt extrusion (HME) and to investigate the distribution of drugs using instrumental analyses. For the feasibility of HME method, a very low amount of coumarin-6, a fluorescent dye, was used to visualize distribution images using confocal laser scanning microscope (CLSM). Limaprost, tamsulosin and glimepiride were then used as low-dose model drugs to study the applicability of HME for content uniformity and distribution behaviors. Hydrophilic thermosensitive polymers with low melting point, such as Poloxamer188 and polyethylene glycol (PEG) 6000, were chosen as carriers. The melt extrusion was carried out around 50°C, at which both carriers were easily dissolved but model drugs remained in solid form. The physicochemical properties of the hot-melt extrudates, including differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FT-IR), were measured. Content uniformity of the drugs was also checked by HPLC. CLSM imaging showed that model drugs were well distributed throughout the hot-melt extrudate, giving better content uniformity with low batch-to-batch variations compared with simple physical mixtures. DSC, PXRD and FT-IR data showed that there was no interaction or interference between model drugs and thermosensitive polymers. The current HME methods could be used to prepare uniformly distributed and reproducible solid dosage forms containing very low dose drugs for further pharmaceutical applications.

  10. Low-dose gamma irradiation following hot water immersion of papaya (Carica papaya linn.) fruits provides additional control of postharvest fungal infection to extend shelf life

    NASA Astrophysics Data System (ADS)

    Rashid, M. H. A.; Grout, B. W. W.; Continella, A.; Mahmud, T. M. M.

    2015-05-01

    Low-dose gamma irradiation (0.08 kGy over 10 min), a level significantly below that required to satisfy the majority of international quarantine regulations, has been employed to provide a significant reduction in visible fungal infection on papaya fruit surfaces. This is appropriate for local and national markets in producer countries where levels of commercial acceptability can be retained despite surface lesions due to fungal infection. Irradiation alone and in combination with hot-water immersion (50 °C for 10 min) has been applied to papaya (Carica papaya L.) fruits at both the mature green and 1/3 yellow stages of maturity. The incidence and severity of surface fungal infections, including anthracnose, were significantly reduced by the combined treatment compared to irradiation or hot water treatment alone, extending storage at 11 °C by 13 days and retaining commercial acceptability. The combined treatment had no significant, negative impact on ripening, with quality characteristics such as surface and internal colour change, firmness, soluble solids, acidity and vitamin C maintained at acceptable levels.

  11. Comparison of methods for the measurement of radiation dose distributions in high dose rate (HDR) brachytherapy: Ge-doped optical fiber, EBT3 Gafchromic film, and PRESAGE{sup Registered-Sign} radiochromic plastic

    SciTech Connect

    Palmer, A. L.; Di Pietro, P.; Alobaidli, S.; Issa, F.; Doran, S.; Bradley, D.; Nisbet, A.

    2013-06-15

    Purpose: Dose distribution measurement in clinical high dose rate (HDR) brachytherapy is challenging, because of the high dose gradients, large dose variations, and small scale, but it is essential to verify accurate treatment planning and treatment equipment performance. The authors compare and evaluate three dosimetry systems for potential use in brachytherapy dose distribution measurement: Ge-doped optical fibers, EBT3 Gafchromic film with multichannel analysis, and the radiochromic material PRESAGE{sup Registered-Sign} with optical-CT readout. Methods: Ge-doped SiO{sub 2} fibers with 6 {mu}m active core and 5.0 mm length were sensitivity-batched and their thermoluminescent properties used via conventional heating and annealing cycles. EBT3 Gafchromic film of 30 {mu}m active thickness was calibrated in three color channels using a nominal 6 MV linear accelerator. A 48-bit transmission scanner and advanced multichannel analysis method were utilized to derive dose measurements. Samples of the solid radiochromic polymer PRESAGE{sup Registered-Sign }, 60 mm diameter and 100 mm height, were analyzed with a parallel beam optical CT scanner. Each dosimetry system was used to measure the dose as a function of radial distance from a Co-60 HDR source, with results compared to Monte Carlo TG-43 model data. Each system was then used to measure the dose distribution along one or more lines through typical clinical dose distributions for cervix brachytherapy, with results compared to treatment planning system (TPS) calculations. Purpose-designed test objects constructed of Solid Water and held within a full-scatter water tank were utilized. Results: All three dosimetry systems reproduced the general shape of the isolated source radial dose function and the TPS dose distribution. However, the dynamic range of EBT3 exceeded those of doped optical fibers and PRESAGE{sup Registered-Sign }, and the latter two suffered from unacceptable noise and artifact. For the experimental

  12. Preservation of physical properties of stochastic Maxwell equations with additive noise via stochastic multi-symplectic methods

    SciTech Connect

    Chen, Chuchu Hong, Jialin Zhang, Liying

    2016-02-01

    Stochastic Maxwell equations with additive noise are a system of stochastic Hamiltonian partial differential equations intrinsically, possessing the stochastic multi-symplectic conservation law. It is shown that the averaged energy increases linearly with respect to the evolution of time and the flow of stochastic Maxwell equations with additive noise preserves the divergence in the sense of expectation. Moreover, we propose three novel stochastic multi-symplectic methods to discretize stochastic Maxwell equations in order to investigate the preservation of these properties numerically. We make theoretical discussions and comparisons on all of the three methods to observe that all of them preserve the corresponding discrete version of the averaged divergence. Meanwhile, we obtain the corresponding dissipative property of the discrete averaged energy satisfied by each method. Especially, the evolution rates of the averaged energies for all of the three methods are derived which are in accordance with the continuous case. Numerical experiments are performed to verify our theoretical results.

  13. Variability in CT lung-nodule quantification: Effects of dose reduction and reconstruction methods on density and texture based features

    PubMed Central

    Lo, P.; Young, S.; Kim, H. J.; Brown, M. S.

    2016-01-01

    Purpose: To investigate the effects of dose level and reconstruction method on density and texture based features computed from CT lung nodules. Methods: This study had two major components. In the first component, a uniform water phantom was scanned at three dose levels and images were reconstructed using four conventional filtered backprojection (FBP) and four iterative reconstruction (IR) methods for a total of 24 different combinations of acquisition and reconstruction conditions. In the second component, raw projection (sinogram) data were obtained for 33 lung nodules from patients scanned as a part of their clinical practice, where low dose acquisitions were simulated by adding noise to sinograms acquired at clinical dose levels (a total of four dose levels) and reconstructed using one FBP kernel and two IR kernels for a total of 12 conditions. For the water phantom, spherical regions of interest (ROIs) were created at multiple locations within the water phantom on one reference image obtained at a reference condition. For the lung nodule cases, the ROI of each nodule was contoured semiautomatically (with manual editing) from images obtained at a reference condition. All ROIs were applied to their corresponding images reconstructed at different conditions. For 17 of the nodule cases, repeat contours were performed to assess repeatability. Histogram (eight features) and gray level co-occurrence matrix (GLCM) based texture features (34 features) were computed for all ROIs. For the lung nodule cases, the reference condition was selected to be 100% of clinical dose with FBP reconstruction using the B45f kernel; feature values calculated from other conditions were compared to this reference condition. A measure was introduced, which the authors refer to as Q, to assess the stability of features across different conditions, which is defined as the ratio of reproducibility (across conditions) to repeatability (across repeat contours) of each feature. Results: The

  14. New method of DNA isolation from two food additives suitable for authentication in polymerase chain reaction assays.

    PubMed

    Urdiaín, Mercedes; Doménech-Sánchez, Antonio; Albertí, Sebastián; Benedí, V Javier; Rosselló, Josep A

    2005-05-04

    Locust bean gum and guar gum are galactomannans used as additives (E 410 and E 412, respectively) in the food industry as stabilizing agents. Analytical discrimination between the two additives in gums and foods is now feasible by molecular techniques. However, only complex and time-consuming DNA isolation protocols are available to date. We have developed simple improved protocols to obtain enough DNA suitable for PCR amplification from a few milligrams of commercial E 410 and E 412 additives (containing more than 75% polysaccharides). The suspension of additives in water or 10 mM Tris-HCl, pH 8.5, efficiently recovers DNA suitable for authentication in PCR assays. However, the Tris method was much more efficient for the extraction of DNA from E 410 than for E 412 additives. Conversely, the water method was the most suitable for detecting DNA extracted from E 412 or from E 410/E 412 mixtures. Combined with the use of the two specific ribosomal primer pairs previously designed, our methods are well-suited for a fast and simple high-throughput sample treatment of commercial gums for molecular certification.

  15. COMPARISON OF IN VITRO-CULTURED AND WILD-TYPE PERKINSUS MARINUS. II: DOSING METHODS AND HOST RESPONSE

    EPA Science Inventory

    Endoparasites must breach host barriers to establish infection and then must survive host internal defenses to cause disease. Such barriers may frustrate attempts to experimentally transmit parasites by ?natural' methods. In addition, the host's condition may affect a study's out...

  16. Methods for estimation of radiation risk in epidemiological studies accounting for classical and Berkson errors in doses.

    PubMed

    Kukush, Alexander; Shklyar, Sergiy; Masiuk, Sergii; Likhtarov, Illya; Kovgan, Lina; Carroll, Raymond J; Bouville, Andre

    2011-02-16

    With a binary response Y, the dose-response model under consideration is logistic in flavor with pr(Y=1 | D) = R (1+R)(-1), R = λ(0) + EAR D, where λ(0) is the baseline incidence rate and EAR is the excess absolute risk per gray. The calculated thyroid dose of a person i is expressed as Dimes=fiQi(mes)/Mi(mes). Here, Qi(mes) is the measured content of radioiodine in the thyroid gland of person i at time t(mes), Mi(mes) is the estimate of the thyroid mass, and f(i) is the normalizing multiplier. The Q(i) and M(i) are measured with multiplicative errors Vi(Q) and ViM, so that Qi(mes)=Qi(tr)Vi(Q) (this is classical measurement error model) and Mi(tr)=Mi(mes)Vi(M) (this is Berkson measurement error model). Here, Qi(tr) is the true content of radioactivity in the thyroid gland, and Mi(tr) is the true value of the thyroid mass. The error in f(i) is much smaller than the errors in ( Qi(mes), Mi(mes)) and ignored in the analysis. By means of Parametric Full Maximum Likelihood and Regression Calibration (under the assumption that the data set of true doses has lognormal distribution), Nonparametric Full Maximum Likelihood, Nonparametric Regression Calibration, and by properly tuned SIMEX method we study the influence of measurement errors in thyroid dose on the estimates of λ(0) and EAR. The simulation study is presented based on a real sample from the epidemiological studies. The doses were reconstructed in the framework of the Ukrainian-American project on the investigation of Post-Chernobyl thyroid cancers in Ukraine, and the underlying subpolulation was artificially enlarged in order to increase the statistical power. The true risk parameters were given by the values to earlier epidemiological studies, and then the binary response was simulated according to the dose-response model.

  17. Is the use of the cervical vertebrae maturation method justified to determine skeletal age? A comparison of radiation dose of two strategies for skeletal age estimation.

    PubMed

    Patcas, Raphael; Signorelli, Luca; Peltomäki, Timo; Schätzle, Marc

    2013-10-01

    The aim of this study was to assess effective doses of a lateral cephalogram radiograph with and without thyroid shield and compare the differences with the radiation dose of a hand-wrist radiograph. Thermoluminescent dosimeters were placed at 19 different sites in the head and neck of a tissue-equivalent human skull (RANDO phantom). Analogue lateral cephalograms with and without thyroid shield (67 kV, 250 mA, 10 mAs) and hand-wrist radiographs (40 kV, 250 mA, 10 mAs) were obtained. The effective doses were calculated using the 2007 International Commission on Radiological Protection recommendations. The effective dose for conventional lateral cephalogram without a thyroid shield was 5.03 microsieverts (µSv). By applying a thyroid shield to the RANDO phantom, a remarkable dose reduction of 1.73 µSv could be achieved. The effective dose of a conventional hand-wrist radiograph was calculated to be 0.16 µSv. Adding the effective dose of the hand-wrist radiograph to the effective dose of the lateral cephalogram with thyroid shield resulted in a cumulative effective dose of 3.46 µSv. Without thyroid shield, the effective dose of a lateral cephalogram was approximately 1.5-fold increased than the cumulative effective dose of a hand-wrist radiograph and a lateral cephalogram with thyroid shield. Thyroid is an organ that is very sensitive to radiation exposure. Its shielding will significantly reduce the effective dose. An additional hand-wrist radiograph, involving no vulnerable tissues, however, causes very little radiation risk. In accordance with the ALARA (As Low As Reasonably Achievable) principle, if an evaluation of skeletal age is indicated, an additional hand-wrist radiograph seems much more justifiable than removing the thyroid shield.

  18. Rotational self-diffusion in suspensions of charged particles: simulations and revised Beenakker-Mazur and pairwise additivity methods

    NASA Astrophysics Data System (ADS)

    Makuch, Karol; Heinen, Marco; Abade, Gustavo Coelho; Nägele, Gerhard

    To the present day, the Beenakker-Mazur (BM) method is the most comprehensive statistical physics approach to the calculation of short-time transport properties of colloidal suspensions. A revised version of the BM method with an improved treatment of hydrodynamic interactions is presented and evaluated regarding the rotational short-time self-diffusion coefficient, $D^r$ , of suspensions of charged particles interacting by a hard-sphere plus screened Coulomb (Yukawa) pair potential. To assess the accuracy of the method, elaborate simulations of $D^r$ have been performed, covering a broad range of interaction parameters and particle concentrations. The revised BM method is compared in addition with results by a simplifying pairwise additivity (PA) method in which the hydrodynamic interactions are treated on a two-body level. The static pair correlation functions re- quired as input to both theoretical methods are calculated using the Rogers-Young integral equation scheme. While the revised BM method reproduces the general trends of the simulation results, it systematically and significantly underestimates the rotational diffusion coefficient. The PA method agrees well with the simulation data at lower volume fractions, but at higher concentrations $D^r$ is likewise underestimated. For a fixed value of the pair potential at mean particle distance comparable to the thermal energy, $D^r$ increases strongly with increasing Yukawa potential screening parameter.

  19. High-throughput automated dissolution method applicable for a wide dose range of controlled release pellets.

    PubMed

    Petruševska, Marija; Horvat, Matej; Peternel, Luka; Kristan, Katja

    2016-01-01

    The aim of the present study was to demonstrate the application of an automated high-throughput (HT) dissolution method as a useful screening tool for characterization of controlled release pellets in the formulation development phase. Five controlled release pellet formulations with drug substances exhibiting high or low solubility were chosen to investigate the correlation of the automated HT dissolution method with the conventional dissolution testing. Overall, excellent correlations (R(2 )>( )0.96) between the HT and the conventional dissolution method were obtained. In one case the initial unsatisfactory correlation (R(2 )=( )0.84) and poor method agreement (SD = 12.5) was improved by optimizing the HT dissolution method with design of experiment approach. Here in comparison to initial experimental HT dissolution settings, increased amount of pellets (25% of the capsule filling mass), lower temperature (22 °C) and no shaking resulted in significantly better correlation (R(2 )=( )0.97) and method agreement (SD = 5.3). These results show that such optimization is valuable for the development of HT dissolution methods. In conclusion, the high correlation of dissolution profiles obtained from the conventional and the automated HT dissolution method combined with low within-sample and measurement system variability, justifies the utilization of the automated HT dissolution method during development phase of controlled release pellets.

  20. The effect of addition of low dose fentanyl to epidural bupivacaine (0.5%) in patients undergoing elective caesarean section: A randomized, parallel group, double blind, placebo controlled study

    PubMed Central

    Parate, LH; Manjrekar, SP; Anandaswamy, TC; Manjunath, B

    2015-01-01

    Background: Opioids have synergistic action with local anesthetics which may alter characteristics of epidural block. Giving opioids to mother before delivery of baby is still fully not accepted with some fearing risk of neonatal depression. Aims: Our primary aim was to evaluate the analgesic effect of addition of 50 μg fentanyl to epidural 0.5% bupivacaine in patients undergoing elective caesarean section using visual analog scale. The secondary aim was to assess onset of analgesia, volume of drug required to achieve T6 level, grade and duration of motor block and Apgar score. Materials and Methods: In this prospective, randomized, double blind, placebo controlled study 64 patients scheduled for elective caesarean section under epidural anesthesia were randomly divided into two groups of 32 each. The fentanyl group received 1ml of 50 μg fentanyl and the saline group received 1ml of normal saline mixed with 10ml of 0.5% bupivacaine for epidural anesthesia. VAS score, time to achieve T6 level, dose of bupivacaine, intraoperative analgesic consumption and duration of analgesia, grade and duration of motor block and any adverse maternal and neonatal effects were noted. Statistical Analysis: Data was analyzed using Students t test, chi-square test and Mann-Whitney U-test. The values of P < 0.05 were considered statistically significant. Results: Fentanyl improved the VAS score significantly (1.6 ± 1.32) compared to the saline group (3.77 ± 1.0, P < 0.0001). It also reduced the intraoperaitve analgesic supplementation compared to the saline group. (P = 0.031). The postoperative duration of analgesia was prolonged in the fentanyl group (275.80 ± 13.61 min) compared to the saline group (191.47 ± 12.16 min, P < 0.0001). The other characteristics of epidural block were unaltered. Conclusion: Addition of 50 μg fentanyl to epidural 0.5% bupivacaine significantly reduces the VAS score. It also reduces intra-operative analgesia supplementation and prolongs the duration

  1. Calculation of internal dose from ingested soil-derived uranium in humans: Application of a new method.

    PubMed

    Träber, S C; Li, W B; Höllriegl, V; Nebelung, K; Michalke, B; Rühm, W; Oeh, U

    2015-08-01

    The aim of the present study was to determine the internal dose in humans after the ingestion of soil highly contaminated with uranium. Therefore, an in vitro solubility assay was performed to estimate the bioaccessibility of uranium for two types of soil. Based on the results, the corresponding bioavailabilities were assessed by using a recently published method. Finally, these bioavailability data were used together with the biokinetic model of uranium to assess the internal doses for a hypothetical but realistic scenario characterized by a daily ingestion of 10 mg of soil over 1 year. The investigated soil samples were from two former uranium mining sites of Germany with (238)U concentrations of about 460 and 550 mg/kg. For these soils, the bioavailabilities of (238)U were quantified as 0.18 and 0.28 % (geometric mean) with 2.5th percentiles of 0.02 and 0.03 % and 97.5th percentiles of 1.48 and 2.34 %, respectively. The corresponding calculated annual committed effective doses for the assumed scenario were 0.4 and 0.6 µSv (GM) with 2.5th percentiles of 0.2 and 0.3 µSv and 97.5th percentiles of 1.6 and 3.0 µSv, respectively. These annual committed effective doses are similar to those from natural uranium intake by food and drinking water, which is estimated to be 0.5 µSv. Based on the present experimental data and the selected ingestion scenario, the investigated soils-although highly contaminated with uranium-are not expected to pose any major health risk to humans related to radiation.

  2. SU-E-T-224: Is Monte Carlo Dose Calculation Method Necessary for Cyberknife Brain Treatment Planning?

    SciTech Connect

    Wang, L; Fourkal, E; Hayes, S; Jin, L; Ma, C

    2014-06-01

    Purpose: To study the dosimetric difference resulted in using the pencil beam algorithm instead of Monte Carlo (MC) methods for tumors adjacent to the skull. Methods: We retrospectively calculated the dosimetric differences between RT and MC algorithms for brain tumors treated with CyberKnife located adjacent to the skull for 18 patients (total of 27 tumors). The median tumor sizes was 0.53-cc (range 0.018-cc to 26.2-cc). The absolute mean distance from the tumor to the skull was 2.11 mm (range - 17.0 mm to 9.2 mm). The dosimetric variables examined include the mean, maximum, and minimum doses to the target, the target coverage (TC) and conformality index. The MC calculation used the same MUs as the RT dose calculation without further normalization and 1% statistical uncertainty. The differences were analyzed by tumor size and distance from the skull. Results: The TC was generally reduced with the MC calculation (24 out of 27 cases). The average difference in TC between RT and MC was 3.3% (range 0.0% to 23.5%). When the TC was deemed unacceptable, the plans were re-normalized in order to increase the TC to 99%. This resulted in a 6.9% maximum change in the prescription isodose line. The maximum changes in the mean, maximum, and minimum doses were 5.4 %, 7.7%, and 8.4%, respectively, before re-normalization. When the TC was analyzed with regards to target size, it was found that the worst coverage occurred with the smaller targets (0.018-cc). When the TC was analyzed with regards to the distance to the skull, there was no correlation between proximity to the skull and TC between the RT and MC plans. Conclusions: For smaller targets (< 4.0-cc), MC should be used to re-evaluate the dose coverage after RT is used for the initial dose calculation in order to ensure target coverage.

  3. Source Distribution Method for Unsteady One-Dimensional Flows With Small Mass, Momentum, and Heat Addition and Small Area Variation

    NASA Technical Reports Server (NTRS)

    Mirels, Harold

    1959-01-01

    A source distribution method is presented for obtaining flow perturbations due to small unsteady area variations, mass, momentum, and heat additions in a basic uniform (or piecewise uniform) one-dimensional flow. First, the perturbations due to an elemental area variation, mass, momentum, and heat addition are found. The general solution is then represented by a spatial and temporal distribution of these elemental (source) solutions. Emphasis is placed on discussing the physical nature of the flow phenomena. The method is illustrated by several examples. These include the determination of perturbations in basic flows consisting of (1) a shock propagating through a nonuniform tube, (2) a constant-velocity piston driving a shock, (3) ideal shock-tube flows, and (4) deflagrations initiated at a closed end. The method is particularly applicable for finding the perturbations due to relatively thin wall boundary layers.

  4. Simultaneous spectrophotometric determination of chromium(VI) and iron (III) by H-point standard addition method

    NASA Astrophysics Data System (ADS)

    Larionova, E. V.; Bulygina, K. A.

    2016-02-01

    In this work the possibility of simultaneous spectrophotometric determination of chromium (VI) and iron (III) in alloys with help of the mixed organic reagent (diphenylcarbazide and 1,10-phenanthroline) is studied. We have applied H-point standard addition method to determine concentrations of chromium (VI) and iron (III) from the mixture. The pure signals of complexes of chromium (VI) with diphenylcarbazide and iron (III) with the 1,10-phenanthroline and their calibration plots are previously carried out. We established the possibility of simultaneous determination of chromium (VI) and iron (III) in the different concentration ranges by H-point standard addition method. Correctness of determination of concentration by means of the offered technique is proved by "added-found" method for a series of mixtures with different ratios of concentration of chromium (VI) and iron (III). It is founded that the error of determination of concentration doesn't exceed 33%.

  5. Comparative evaluation of two dose optimization methods for image-guided, highly-conformal, tandem and ovoids cervix brachytherapy planning.

    PubMed

    Ren, Jiyun; Menon, Geetha; Sloboda, Ron

    2013-04-07

    Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning--Nelder-Mead simplex (NMS) and simulated annealing (SA)--for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.

  6. Comparative evaluation of two dose optimization methods for image-guided, highly-conformal, tandem and ovoids cervix brachytherapy planning

    NASA Astrophysics Data System (ADS)

    Ren, Jiyun; Menon, Geetha; Sloboda, Ron

    2013-04-01

    Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning—Nelder-Mead simplex (NMS) and simulated annealing (SA)—for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.

  7. Novel orthogonal liquid chromatography methods to dose neurotransmitters involved in Parkinson's disease.

    PubMed

    Sardella, Roccaldo; Scorzoni, Stefania; Conte, Carmela; Lisanti, Antonella; Ianni, Federica; Natalini, Benedetto

    2014-09-01

    Parkinson's disease is a multifactorial neurodegenerative disorder, characterized by a reduction of dopamine (DA) levels. The molecular pathways involved in the pathogenesis of disease have not yet been fully disclosed. Therefore, developing new diagnostic methods and tools to evaluate the depletion of DA and of some of its metabolites (3,4-dihydroxyphenylacetic acid, homovanillic acid, and 3-methoxytyramine) is of outstanding importance for biochemical evaluations. Moreover, neurons responsible for DA release also produce the neurotransmitter gamma-aminobutyric acid (GABA), thus, quantitative measurements of GABA levels can have a relevant impact for a further understanding of the biochemical processes involved in the neurodegenerative event. In the present study, two HPLC methods based on the reversed-phase ion-pairing chromatography (RP-IPC) and the hydrophilic liquid interaction chromatography (HILIC) concepts were developed to allow the quantification of DA and its metabolites as well as GABA levels in mouse striatal and cortical tissue homogenates. The two fairly orthogonal HPLC methods were directly applied to the biological samples, without preliminary derivatization of the compounds of interest. A high level of selectivity was obtained for DA metabolites and GABA by running the gradient RP-IPC method with a volatile ion-pairing reagent, which makes it suitable for the quantitative assay of four out of five compounds. Matrix deriving interferences unabled the base-line separation of DA which was instead successfully achieved with the HILIC-based method. To avail of HPLC methods providing distinct selectivity profiles, makes possible the correct species quantification and allows to compensate the intrinsic limits characterizing all chromatographic methods.

  8. Developing population pharmacokinetic parameters for high-dose methotrexate therapy: implication of correlations among developed parameters for individual parameter estimation using the Bayesian least-squares method.

    PubMed

    Watanabe, Masahiro; Fukuoka, Noriyasu; Takeuchi, Toshiki; Yamaguchi, Kazunori; Motoki, Takahiro; Tanaka, Hiroaki; Kosaka, Shinji; Houchi, Hitoshi

    2014-01-01

    Bayesian estimation enables the individual pharmacokinetic parameters of the medication administrated to be estimated using only a few blood concentrations. Due to wide inter-individual variability in the pharmacokinetics of methotrexate (MTX), the concentration of MTX needs to be frequently determined during high-dose MTX therapy in order to prevent toxic adverse events. To apply the benefits of Bayesian estimation to cases treated with this therapy, we attempted to develop an estimation method using the Bayesian least-squares method, which is commonly used for therapeutic monitoring in a clinical setting. Because this method hypothesizes independency among population pharmacokinetic parameters, we focused on correlations among population pharmacokinetic parameters used to estimate individual parameters. A two-compartment model adequately described the observed concentration of MTX. The individual pharmacokinetic parameters of MTX were estimated in 57 cases using the maximum likelihood method. Among the available parameters accounting for a 2-compartment model, V1, k10, k12, and k21 were found to be the combination showing the weakest correlations, which indicated that this combination was best suited to the Bayesian least-squares method. Using this combination of population pharmacokinetic parameters, Bayesian estimation provided an accurate estimation of individual parameters. In addition, we demonstrated that the degree of correlation among population pharmacokinetic parameters used in the estimation affected the precision of the estimates. This result highlights the necessity of assessing correlations among the population pharmacokinetic parameters used in the Bayesian least-squares method.

  9. [A method of the interactive visual optimization of the therapeutic dose field in contact radiation therapy of malignant tumors (theoretical aspects of the problem)].

    PubMed

    Klepper, L Ia

    2003-01-01

    The mathematical and interpretation tasks of a directed shaping of dose fields in the contrast radiation therapy of malignant tumors are defined on the basis of the dose-field homogeneity parameter. A schematic iterative algorithm of how to solve the tasks is described. A method for the visual optimization of such field is elaborated; it is based on preset limits to the dose field in the lesion focus and in the healthy organs and tissues. The dose field is shaped by an applicator with multiple terminal fixed positions of irradiation sources--the effect is achieved due to variability of their exposure duration.

  10. Evaluation of the Patient Effective Dose in Whole Spine Scanography Based on the Automatic Image Pasting Method for Digital Radiography

    PubMed Central

    Kim, Jung-Su; Yoon, Sang-Wook; Seo, Deok-Nam; Nam, So-Ra; Kim, Jung-Min

    2016-01-01

    Background: Whole spine scanography (WSS) is a radiologic examination that requires whole body X-ray exposure. Consequently, the amount of patient radiation exposure is higher than the radiation dose following routine X-ray examination. Objectives: Several studies have evaluated the patient effective dose (ED) following single exposure film-screen WSS. The objective of this study was to evaluate patient ED during WSS, based on the automatic image pasting method for multiple exposure digital radiography (APMDR). Further, the calculated EDs were compared with the results of previous studies involving single exposure film-screen WSS. Patients and Methods: We evaluated the ED of 50 consecutive patients (M:F = 28:22) who underwent WSS using APMDR. The anterior-posterior (AP) and lateral (LAT) projection EDs were evaluated based on the Monte Carlo simulation. Results: Using APMDR, the mean number of exposures was 6.1 for AP and 6.5 for LAT projections. LAT projections required more exposures (6.55%) than AP projections. The mean ED was 0.6276 mSv (AP) and 0.6716 mSv (LAT). The mean ED for LAT projections was 0.6061 mSv in automatic exposure control (AEC) and 0.7694 mSv in manual mode. The relationship between dose-area-product (DAP) and ED revealed a proportional correlation (AP, R2 = 0.943; LAT, R2 = 0.773). Compared to prior research involving single exposure screen-film WSS, the patient ED following WSS using APMDR was lower on AP than on LAT projections. Conclusion: Despite multiple exposures, ED control is more effective if WSS is performed using APMDR in the AEC mode. PMID:27110338

  11. Patient-specific organ dose estimation during transcatheter arterial embolization using Monte Carlo method and adaptive organ segmentation

    NASA Astrophysics Data System (ADS)

    Tsai, Hui-Yu; Lin, Yung-Chieh; Tyan, Yeu-Sheng

    2014-11-01

    The purpose of this study was to evaluate organ doses for individual patients undergoing interventional transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) using measurement-based Monte Carlo simulation and adaptive organ segmentation. Five patients were enrolled in this study after institutional ethical approval and informed consent. Gafchromic XR-RV3 films were used to measure entrance surface dose to reconstruct the nonuniform fluence distribution field as the input data in the Monte Carlo simulation. XR-RV3 films were used to measure entrance surface doses due to their lower energy dependence compared with that of XR-RV2 films. To calculate organ doses, each patient's three-dimensional dose distribution was incorporated into CT DICOM images with image segmentation using thresholding and k-means clustering. Organ doses for all patients were estimated. Our dose evaluation system not only evaluated entrance surface doses based on measurements, but also evaluated the 3D dose distribution within patients using simulations. When film measurements were unavailable, the peak skin dose (between 0.68 and 0.82 of a fraction of the cumulative dose) can be calculated from the cumulative dose obtained from TAE dose reports. Successful implementation of this dose evaluation system will aid radiologists and technologists in determining the actual dose distributions within patients undergoing TAE.

  12. A method for online verification of adapted fields using an independent dose monitor

    SciTech Connect

    Chang Jina; Norrlinger, Bernhard D.; Heaton, Robert K.; Jaffray, David A.; Cho, Young-Bin; Islam, Mohammad K.; Mahon, Robert

    2013-07-15

    Purpose: Clinical implementation of online adaptive radiotherapy requires generation of modified fields and a method of dosimetric verification in a short time. We present a method of treatment field modification to account for patient setup error, and an online method of verification using an independent monitoring system.Methods: The fields are modified by translating each multileaf collimator (MLC) defined aperture in the direction of the patient setup error, and magnifying to account for distance variation to the marked isocentre. A modified version of a previously reported online beam monitoring system, the integral quality monitoring (IQM) system, was investigated for validation of adapted fields. The system consists of a large area ion-chamber with a spatial gradient in electrode separation to provide a spatially sensitive signal for each beam segment, mounted below the MLC, and a calculation algorithm to predict the signal. IMRT plans of ten prostate patients have been modified in response to six randomly chosen setup errors in three orthogonal directions.Results: A total of approximately 49 beams for the modified fields were verified by the IQM system, of which 97% of measured IQM signal agree with the predicted value to within 2%.Conclusions: The modified IQM system was found to be suitable for online verification of adapted treatment fields.

  13. 78 FR 64030 - Monitoring Criteria and Methods To Calculate Occupational Radiation Doses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-25

    ... Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2013-0234. Address... methods: Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2013... search, select ``ADAMS Public Documents'' and then select ``Begin Web- based ADAMS Search.'' For...

  14. Comparison of two mosquito bioassay methods for the estimate of minimum effective dose in repellents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is expected that laboratory-based repellent bioassays should reliably evaluate the efficacy of compounds that deter mosquito feeding behavior. The variety of repellent bioassays available allows for flexibility in design, but makes it difficult to compare any two methods, including in vitro and i...

  15. [Denoising and assessing method of additive noise in the ultraviolet spectrum of SO2 in flue gas].

    PubMed

    Zhou, Tao; Sun, Chang-Ku; Liu, Bin; Zhao, Yu-Mei

    2009-11-01

    The problem of denoising and assessing method of the spectrum of SO2 in flue gas was studied based on DOAS. The denoising procedure of the additive noise in the spectrum was divided into two parts: reducing the additive noise and enhancing the useful signal. When obtaining the absorption feature of measured gas, a multi-resolution preprocessing method of original spectrum was adopted for denoising by DWT (discrete wavelet transform). The signal energy operators in different scales were used to choose the denoising threshold and separate the useful signal from the noise. On the other hand, because there was no sudden change in the spectra of flue gas in time series, the useful signal component was enhanced according to the signal time dependence. And the standard absorption cross section was used to build the ideal absorption spectrum with the measured gas temperature and pressure. This ideal spectrum was used as the desired signal instead of the original spectrum in the assessing method to modify the SNR (signal-noise ratio). There were two different environments to do the proof test-in the lab and at the scene. In the lab, SO2 was measured several times with the system using this method mentioned above. The average deviation was less than 1.5%, while the repeatability was less than 1%. And the short range experiment data were better than the large range. In the scene of a power plant whose concentration of flue gas had a large variation range, the maximum deviation of this method was 2.31% in the 18 groups of contrast data. The experimental results show that the denoising effect of the scene spectrum was better than that of the lab spectrum. This means that this method can improve the SNR of the spectrum effectively, which is seriously polluted by additive noise.

  16. Quantifying uncertainty of determination by standard additions and serial dilutions methods taking into account standard uncertainties in both axes.

    PubMed

    Hyk, Wojciech; Stojek, Zbigniew

    2013-06-18

    The analytical expressions for the calculation of the standard uncertainty of the predictor variable either extrapolated or interpolated from a calibration line that takes into account uncertainties in both axes have been derived and successfully verified using the Monte Carlo modeling. These expressions are essential additions to the process of the analyte quantification realized with either the method of standard additions (SAM) or the method of serial dilutions (MSD). The latter one has been proposed as an alternative approach to the SAM procedure. In the MSD approach instead of the sequence of standard additions, the sequence of solvent additions to the spiked sample is performed. The comparison of the calculation results based on the expressions derived to their equivalents obtained from the Monte Carlo simulation, applied to real experimental data sets, confirmed that these expressions are valid in real analytical practice. The estimation of the standard uncertainty of the analyte concentration, quantified via either SAM or MSD or simply a calibration curve, is of great importance for the construction of the uncertainty budget of an analytical procedure. The correct estimation of the standard uncertainty of the analyte concentration is a key issue in the quality assurance in the instrumental analysis.

  17. A simple pharmacokinetic method to evaluate the pulmonary dose in clinical practice--analyses of inhaled sodium cromoglycate.

    PubMed

    Lindström, Maria; Svensson, Jan Olof; Meurling, Lennart; Svartengren, Katharina; Anderson, Martin; Svartengren, Magnus

    2004-01-01

    When the expected effect of an inhaled drug is not achieved, the cause could be poor inhalation technique and consequently a low pulmonary dose. A simple in vivo test to evaluate the pulmonary dose would be a benefit. This study evaluates the relative and systemic bioavailability following inhalation of nebulized sodium cromoglycate (SCG) in healthy subjects. Blood samples were collected during 240 min and urine was collected in two portions, up to 6 h post-inhalation. Two exposures were performed and comparisons based on the quantification of drug in plasma and urine by a high-performance liquid chromatography (HPLC) procedure were done. In one of the exposures, a pulmonary function test was performed to study if an expected effect of increased absorption could be detected. There was a good correlation between the two exposures shown in the plasma concentrations, but not in the urine analyses. The forced exhaled volume manoeuvres were associated with a higher Cmax and plasma concentrations up to 60 min post-inhalation (P<0.01). This effect was not detected in the urine analyses. We conclude that this pharmacokinetic method with inhaled SCG and plasma analyses could be used to evaluate individual inhalation technique. The HPLC method used was rapid and had adequate sensitivity.

  18. Development of modern approach to absorbed dose assessment in radionuclide therapy, based on Monte Carlo method simulation of patient scintigraphy

    NASA Astrophysics Data System (ADS)

    Lysak, Y. V.; Klimanov, V. A.; Narkevich, B. Ya

    2017-01-01

    One of the most difficult problems of modern radionuclide therapy (RNT) is control of the absorbed dose in pathological volume. This research presents new approach based on estimation of radiopharmaceutical (RP) accumulated activity value in tumor volume, based on planar scintigraphic images of the patient and calculated radiation transport using Monte Carlo method, including absorption and scattering in biological tissues of the patient, and elements of gamma camera itself. In our research, to obtain the data, we performed modeling scintigraphy of the vial with administered to the patient activity of RP in gamma camera, the vial was placed at the certain distance from the collimator, and the similar study was performed in identical geometry, with the same values of activity of radiopharmaceuticals in the pathological target in the body of the patient. For correct calculation results, adapted Fisher-Snyder human phantom was simulated in MCNP program. In the context of our technique, calculations were performed for different sizes of pathological targets and various tumors deeps inside patient’s body, using radiopharmaceuticals based on a mixed β-γ-radiating (131I, 177Lu), and clear β- emitting (89Sr, 90Y) therapeutic radionuclides. Presented method can be used for adequate implementing in clinical practice estimation of absorbed doses in the regions of interest on the basis of planar scintigraphy of the patient with sufficient accuracy.

  19. Assessment of shielding analysis methods, codes, and data for spent fuel transport/storage applications. [Radiation dose rates from shielded spent fuels and high-level radioactive waste

    SciTech Connect

    Parks, C.V.; Broadhead, B.L.; Hermann, O.W.; Tang, J.S.; Cramer, S.N.; Gauthey, J.C.; Kirk, B.L.; Roussin, R.W.

    1988-07-01

    This report provides a preliminary assessment of the computational tools and existing methods used to obtain radiation dose rates from shielded spent nuclear fuel and high-level radioactive waste (HLW). Particular emphasis is placed on analysis tools and techniques applicable to facilities/equipment designed for the transport or storage of spent nuclear fuel or HLW. Applications to cask transport, storage, and facility handling are considered. The report reviews the analytic techniques for generating appropriate radiation sources, evaluating the radiation transport through the shield, and calculating the dose at a desired point or surface exterior to the shield. Discrete ordinates, Monte Carlo, and point kernel methods for evaluating radiation transport are reviewed, along with existing codes and data that utilize these methods. A literature survey was employed to select a cadre of codes and data libraries to be reviewed. The selection process was based on specific criteria presented in the report. Separate summaries were written for several codes (or family of codes) that provided information on the method of solution, limitations and advantages, availability, data access, ease of use, and known accuracy. For each data library, the summary covers the source of the data, applicability of these data, and known verification efforts. Finally, the report discusses the overall status of spent fuel shielding analysis techniques and attempts to illustrate areas where inaccuracy and/or uncertainty exist. The report notes the advantages and limitations of several analysis procedures and illustrates the importance of using adequate cross-section data sets. Additional work is recommended to enable final selection/validation of analysis tools that will best meet the US Department of Energy's requirements for use in developing a viable HLW management system. 188 refs., 16 figs., 27 tabs.

  20. Comparative analysis between radiation doses obtained by EPR dosimetry using tooth enamel and established analytical methods for the population of radioactively contaminated territories.

    PubMed

    Ivannikov, Alexander I; Skvortsov, Valeri G; Stepanenko, Valeri F; Zhumadilov, Kassym Sh

    2014-06-01

    A comparative analysis of radiation doses determined by tooth enamel electron paramagnetic resonance (EPR) spectroscopy and by an acknowledged analytical method is performed for individual doses and for average doses in population of some settlements of the Bryansk region (Russia), which have been contaminated after the Chernobyl nuclear accident. The analysis is performed for doses in the range of 0-200 mGy for individuals and in the range of 0-50 mGy for the averaged populations. The method of orthogonal distance linear regression is used for the analysis. For both data sets the slopes of the regression line close to unity and the intercept close to zero are obtained, which indicates that doses determined by these two methods agree with each other. The root-mean-square difference between the results of EPR and analytical methods is estimated to be 35 mGy for individual doses and 15 mGy for averaged doses, which is consistent with uncertainty of these methods.

  1. Comparative analysis between radiation doses obtained by EPR dosimetry using tooth enamel and established analytical methods for the population of radioactively contaminated territories

    PubMed Central

    Ivannikov, Alexander I.; Skvortsov, Valeri G.; Stepanenko, Valeri F.; Zhumadilov, Kassym Sh.

    2014-01-01

    A comparative analysis of radiation doses determined by tooth enamel electron paramagnetic resonance (EPR) spectroscopy and by an acknowledged analytical method is performed for individual doses and for average doses in population of some settlements of the Bryansk region (Russia), which have been contaminated after the Chernobyl nuclear accident. The analysis is performed for doses in the range of 0–200 mGy for individuals and in the range of 0–50 mGy for the averaged populations. The method of orthogonal distance linear regression is used for the analysis. For both data sets the slopes of the regression line close to unity and the intercept close to zero are obtained, which indicates that doses determined by these two methods agree with each other. The root-mean-square difference between the results of EPR and analytical methods is estimated to be 35 mGy for individual doses and 15 mGy for averaged doses, which is consistent with uncertainty of these methods. PMID:24771210

  2. Application of the standard addition method for the absolute quantification of neutral lipids in microalgae using Nile red.

    PubMed

    Bertozzini, Elena; Galluzzi, Luca; Penna, Antonella; Magnani, Mauro

    2011-10-01

    Microalgae are considered one of the best candidates for biofuel production due to their high content in neutral lipids, therefore, an accurate quantification of these lipids in microalgae is fundamental for the identification of the better candidates as biodiesel source. Nile red is a fluorescent dye widely employed for the quantification of neutral lipids in microalgae. Usually, the fluorescence intensity of the stained samples is correlated to the neutral lipid content determined with standard methods, in order to draw a standard curve and deduce the neutral lipids concentration of the unknown samples positioning their fluorescence intensity values on the curve. Standard methods used for the neutral lipids determination are laborious and often implying solvent extraction and/or other transformation (i.e. saponification or transesterification) of the sample. These methods are also time consuming and may give rise to an underestimation of the lipid content due to variable extraction yields. The approach described in this paper combines the standard addition method and the fluorometric staining using Nile red, avoiding the association of traditional neutral lipids quantification methods to the fluorometric determination. After optimization of instrument parameters and staining conditions, a linear correlation between the fluorescence intensity of each sample stained with the Nile red and its neutral lipids content deduced with the standard addition method was identified. The obtained curve allowed the direct determination of neutral lipids content maintaining a linearity range from 0.12 to 12 μg of neutral lipids per ml of sample, without need of pre-concentration. This curve was then used in the quantification of the neutral lipids content in culture of Skeletonema marinoi (Bacillariophyceae) at different days from the inoculum. This method was also successfully applied on Chaetoceros socialis (Bacillariophyceae) and Alexandrium minutum (Dinophyceae).

  3. An Internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics.

    PubMed

    Gilbert, J; Simoneau, C; Cote, D; Boenke, A

    2000-10-01

    An internet website (http:¿cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-of-charge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.

  4. Standard addition method applied to solid-state stripping voltammetry: determination of zirconium in minerals and ceramic materials.

    PubMed

    Doménech-Carbó, A; Moya-Moreno, M; Doménech-Carbó, M T

    2004-09-01

    An application of the standard addition method to stripping voltammetry of solid materials immobilized in inert electrodes is described. The method allows the determination of the mass fraction of a depositable metal M in a material on addition of known amounts of a standard material containing M to a mixture of that material and a reference compound of a second depositable metal, R. After a reductive deposition step, voltammograms recorded for those modified electrodes immersed in a suitable electrolyte produce stripping peaks for the oxidation of the deposits of M and R. If no intermetallic effects appear the quotients between the peak areas and the peak currents for the stripping oxidation of M and R vary linearly with the mass ratio of the added standard and the reference compound, thus providing an electrochemical method for determining the amount of M in the sample. The method has been applied to the determination of Zr in minerals, ceramic frits, and pigments, using ZnO as reference material and ZrO(2) as the standard.

  5. Net analyte signal standard addition method for simultaneous determination of sulphadiazine and trimethoprim in bovine milk and veterinary medicines.

    PubMed

    Hajian, Reza; Mousavi, Esmat; Shams, Nafiseh

    2013-06-01

    Net analyte signal standard addition method has been used for the simultaneous determination of sulphadiazine and trimethoprim by spectrophotometry in some bovine milk and veterinary medicines. The method combines the advantages of standard addition method with the net analyte signal concept which enables the extraction of information concerning a certain analyte from spectra of multi-component mixtures. This method has some advantages such as the use of a full spectrum realisation, therefore it does not require calibration and prediction step and only a few measurements require for the determination. Cloud point extraction based on the phenomenon of solubilisation used for extraction of sulphadiazine and trimethoprim in bovine milk. It is based on the induction of micellar organised media by using Triton X-100 as an extraction solvent. At the optimum conditions, the norm of NAS vectors increased linearly with concentrations in the range of 1.0-150.0 μmolL(-1) for both sulphadiazine and trimethoprim. The limits of detection (LOD) for sulphadiazine and trimethoprim were 0.86 and 0.92 μmolL(-1), respectively.

  6. Comparative analysis of dose rates in bricks determined by neutron activation analysis, alpha counting and X-ray fluorescence analysis for the thermoluminescence fine grain dating method

    NASA Astrophysics Data System (ADS)

    Bártová, H.; Kučera, J.; Musílek, L.; Trojek, T.

    2014-11-01

    In order to evaluate the age from the equivalent dose and to obtain an optimized and efficient procedure for thermoluminescence (TL) dating, it is necessary to obtain the values of both the internal and the external dose rates from dated samples and from their environment. The measurements described and compared in this paper refer to bricks from historic buildings and a fine-grain dating method. The external doses are therefore negligible, if the samples are taken from a sufficient depth in the wall. However, both the alpha dose rate and the beta and gamma dose rates must be taken into account in the internal dose. The internal dose rate to fine-grain samples is caused by the concentrations of natural radionuclides 238U, 235U, 232Th and members of their decay chains, and by 40K concentrations. Various methods can be used for determining trace concentrations of these natural radionuclides and their contributions to the dose rate. The dose rate fraction from 238U and 232Th can be calculated, e.g., from the alpha count rate, or from the concentrations of 238U and 232Th, measured by neutron activation analysis (NAA). The dose rate fraction from 40K can be calculated from the concentration of potassium measured, e.g., by X-ray fluorescence analysis (XRF) or by NAA. Alpha counting and XRF are relatively simple and are accessible for an ordinary laboratory. NAA can be considered as a more accurate method, but it is more demanding regarding time and costs, since it needs a nuclear reactor as a neutron source. A comparison of these methods allows us to decide whether the time- and cost-saving simpler techniques introduce uncertainty that is still acceptable.

  7. Cone beam CT dose reduction in prostate radiotherapy using Likert scale methods

    PubMed Central

    Newton, Louise A; Jordan, Suzanne; Smith, Ruth

    2016-01-01

    Objective: To use a Likert scale method to optimize image quality (IQ) for cone beam CT (CBCT) soft-tissue matching for image-guided radiotherapy of the prostate. Methods: 23 males with local/locally advanced prostate cancer had the CBCT IQ assessed using a 4-point Likert scale (4 = excellent, no artefacts; 3 = good, few artefacts; 2 = poor, just able to match; 1 = unsatisfactory, not able to match) at three levels of exposure. The lateral separations of the subjects were also measured. The Friedman test and Wilcoxon signed-rank tests were used to determine if the IQ was associated with the exposure level. We used the point-biserial correlation and a χ2 test to investigate the relationship between the separation and IQ. Results: The Friedman test showed that the IQ was related to exposure (p = 2 × 10−7) and the Wilcoxon signed-rank test demonstrated that the IQ decreased as exposure decreased (all p-values <0.005). We did not find a correlation between the IQ and the separation (correlation coefficient 0.045), but for separations <35 cm, it was possible to use the lowest exposure parameters studied. Conclusion: We can reduce exposure factors to 80% of those supplied with the system without hindering the matching process for all patients. For patients with lateral separations <35 cm, the exposure factors can be reduced further to 64% of the original values. Advances in knowledge: Likert scales are a useful tool for measuring IQ in the optimization of CBCT IQ for soft-tissue matching in radiotherapy image guidance applications. PMID:26689092

  8. Novel real function based method to construct heterogeneous porous scaffolds and additive manufacturing for use in medical engineering.

    PubMed

    Yang, Nan; Tian, Yanling; Zhang, Dawei

    2015-11-01

    Heterogeneous porous scaffolds have important applications in biomedical engineering, as they can mimic the structures of natural tissues to achieve the corresponding properties. Here, we introduce a new and easy to implement real function based method for constructing complex, heterogeneous porous structures, including hybrid structures, stochastic structures, functionally gradient structures, and multi-scale structures, or their combinations (e.g., hybrid multi-scale structures). Based on micro-CT data, a femur-mimetic structure with gradient morphology was constructed using our method and fabricated using stereolithography. Results showed that our method could generate gradient porosity or gradient specific surfaces and be sufficiently flexible for use with micro-CT data and additive manufacturing (AM) techniques.

  9. SU-E-T-288: Dose Volume Population Histogram (DVPH): A New Method to Evaluate Intensity Modulated Proton Therapy Plans With Geometrical Uncertainties

    SciTech Connect

    Nguyen, T; Mai, N; Nguyen, B

    2015-06-15

    Purpose: In Proton therapy, especially intensity modulated proton therapy(IMPT), the dose distribution shape is very sensitive to errors due to sharp dose gradients at the Bragg peaks. The concept of the conventional margin is based on the assumption that dose distribution is shifted rather than deformed due to geometrical uncertainties. The goal of this study is to access the validity of the margin concept as well as propose a new approach using Dose Volume Population Histogram (DVPH) in evaluating IMPT plans. Methods: For a prostate case, an intensity modulated proton therapy is optimized based on the conventional PTV based objective function. The plan is evaluated based on the PTV DVH and CTV DVPH (dose volume population histogram) which explicitly taking into account geometric uncertainties. The DVPH is calculated based on 2197 dose distributions at different CTV possible positions for both random and systematic errors. The DVPH with a 90% confidence level is used for the comparison. Results: The minimum dose of the CTV DVPH with a 90% confidence level is only about 18% of the prescribed dose, while the minimum dose of the PTV is 95%. For bladder DVHs, the D50 and D35 is 26% and 30%, compared to 65% and 70% of the prescribed dose from the bladder DVPH with 90% confidence level. Conclusion: The results showed that the PTV concept for ensuring the prescribed dose actually delivered to the CTV is invalid in proton therapy. The good PTV DVH might Result in an underdose to the target and should not be used for IMPT optimization. For OARs, the conventional evaluation approach underestimates dose volume end points. The new concept DVPH has been proved to provide a more accurate DVH evaluation in proton therapy.

  10. Assessment of the point-source method for estimating dose rates to members of the public from exposure to patients with 131I thyroid treatment

    SciTech Connect

    Dewji, Shaheen Azim; Bellamy, Michael B.; Hertel, Nolan E.; Leggett, Richard Wayne; Sherbini, Sami; Saba, Mohammad S.; Eckerman, Keith F.

    2015-09-01

    The U.S. Nuclear Regulatory Commission (USNRC) initiated a contract with Oak Ridge National Laboratory (ORNL) to calculate radiation dose rates to members of the public that may result from exposure to patients recently administered iodine-131 (131I) as part of medical therapy. The main purpose was to compare dose rate estimates based on a point source and target with values derived from more realistic simulations that considered the time-dependent distribution of 131I in the patient and attenuation of emitted photons by the patient’s tissues. The external dose rate estimates were derived using Monte Carlo methods and two representations of the Phantom with Movable Arms and Legs, previously developed by ORNL and the USNRC, to model the patient and a nearby member of the public. Dose rates to tissues and effective dose rates were calculated for distances ranging from 10 to 300 cm between the phantoms and compared to estimates based on the point-source method, as well as to results of previous studies that estimated exposure from 131I patients. The point-source method overestimates dose rates to members of the public in very close proximity to an 131I patient but is a broadly accurate method of dose rate estimation at separation distances of 300 cm or more at times closer to administration.

  11. Assessment of the point-source method for estimating dose rates to members of the public from exposure to patients with 131I thyroid treatment

    DOE PAGES

    Dewji, Shaheen Azim; Bellamy, Michael B.; Hertel, Nolan E.; ...

    2015-09-01

    The U.S. Nuclear Regulatory Commission (USNRC) initiated a contract with Oak Ridge National Laboratory (ORNL) to calculate radiation dose rates to members of the public that may result from exposure to patients recently administered iodine-131 (131I) as part of medical therapy. The main purpose was to compare dose rate estimates based on a point source and target with values derived from more realistic simulations that considered the time-dependent distribution of 131I in the patient and attenuation of emitted photons by the patient’s tissues. The external dose rate estimates were derived using Monte Carlo methods and two representations of the Phantommore » with Movable Arms and Legs, previously developed by ORNL and the USNRC, to model the patient and a nearby member of the public. Dose rates to tissues and effective dose rates were calculated for distances ranging from 10 to 300 cm between the phantoms and compared to estimates based on the point-source method, as well as to results of previous studies that estimated exposure from 131I patients. The point-source method overestimates dose rates to members of the public in very close proximity to an 131I patient but is a broadly accurate method of dose rate estimation at separation distances of 300 cm or more at times closer to administration.« less

  12. Fluorometric method for rapid detection of DNA strand breaks in human white blood cells produced by low doses of radiation

    SciTech Connect

    Birnboim, H.C.; Jevcak, J.J.

    1981-05-01

    DNA strand breaks can be detected with great sensitivity by exposing crude cell lysates to alkaline solutions and monitoring the rate of strand unwinding. As little as one strand break per chromosome can be detected. Previous methods for measuring strand unwinding have required physical separation of single- from double-stranded molecules. We now describe conditions under which unwinding can be monitored directly using a fluorescent dye, thus greatly simplifying the analysis. Breaks due to irradiation of blood samples by /sup 60/Co gamma-rays at doses as low as 0.05 to 0.1 gray (5 to 10 rads) were detectable. Rapid rejoining of strand breaks during in vitro incubation at 37 degrees could readily be observed following a dose of one gray. Since the procedure is very rapid and cells can be analyzed directly without the requirement for culturing or radiolabeling, the procedure could be useful in cancer chemotherapy if in vivo damage is to be monitored or for testing the in vitro sensitivity of cells to drugs.

  13. Fluorometric method for rapid detection of DNA strand breaks in human white blood cells produced by low doses of radiation

    SciTech Connect

    Birnboim, H.C.; Jevcak, J.J.

    1981-05-01

    DNA strand breaks can be detected with great sensitivity by exposing crude cell lysates to alkaline solutions and monitoring the rate of strand unwinding. As little as one strand break per chromosome can be detected. Previous methods for measuring strand unwinding have required physical separation of single- from double-stranded molecules. Researchers now describe conditions under which unwinding can be monitored directly using a fluorescent dye, thus greatly simplifying the analysis. Breaks due to irradiation of blood samples by 60Co gamma-rays at doses as low as 0.05 to 0.1 gray were detectable. Rapid rejoining of strand breaks during in vitro incubation at 37 degrees could readily be observed following a dose of one gray. Since the procedure is very rapid and cells can be analyzed directly without the requirement for culturing or radiolabeling, the procedure could be useful in cancer chemotherapy if in vivo damage is to be monitored or for testing the in vitro sensitivity of cells to drugs.

  14. Rotational self-diffusion in suspensions of charged particles: simulations and revised Beenakker-Mazur and pairwise additivity methods.

    PubMed

    Makuch, Karol; Heinen, Marco; Abade, Gustavo Coelho; Nägele, Gerhard

    2015-07-14

    We present a comprehensive joint theory-simulation study of rotational self-diffusion in suspensions of charged particles whose interactions are modeled by the generic hard-sphere plus repulsive Yukawa (HSY) pair potential. Elaborate, high-precision simulation results for the short-time rotational self-diffusion coefficient, D(r), are discussed covering a broad range of fluid-phase state points in the HSY model phase diagram. The salient trends in the behavior of D(r) as a function of reduced potential strength and range, and particle concentration, are systematically explored and physically explained. The simulation results are further used to assess the performance of two semi-analytic theoretical methods for calculating D(r). The first theoretical method is a revised version of the classical Beenakker-Mazur method (BM) adapted to rotational diffusion which includes a highly improved treatment of the salient many-particle hydrodynamic interactions. The second method is an easy-to-implement pairwise additivity (PA) method in which the hydrodynamic interactions are treated on a full two-body level with lubrication corrections included. The static pair correlation functions required as the only input to both theoretical methods are calculated using the accurate Rogers-Young integral equation scheme. While the revised BM method reproduces the general trends of the simulation results, it significantly underestimates D(r). In contrast, the PA method agrees well with the simulation results for D(r) even for intermediately concentrated systems. A simple improvement of the PA method is presented which is applicable for large concentrations.

  15. A non-rigid point matching method with local topology preservation for accurate bladder dose summation in high dose rate cervical brachytherapy.

    PubMed

    Chen, Haibin; Zhong, Zichun; Liao, Yuliang; Pompoš, Arnold; Hrycushko, Brian; Albuquerque, Kevin; Zhen, Xin; Zhou, Linghong; Gu, Xuejun

    2016-02-07

    GEC-ESTRO guidelines for high dose rate cervical brachytherapy advocate the reporting of the D2cc (the minimum dose received by the maximally exposed 2cc volume) to organs at risk. Due to large interfractional organ motion, reporting of accurate cumulative D2cc over a multifractional course is a non-trivial task requiring deformable image registration and deformable dose summation. To efficiently and accurately describe the point-to-point correspondence of the bladder wall over all treatment fractions while preserving local topologies, we propose a novel graphic processing unit (GPU)-based non-rigid point matching algorithm. This is achieved by introducing local anatomic information into the iterative update of correspondence matrix computation in the 'thin plate splines-robust point matching' (TPS-RPM) scheme. The performance of the GPU-based TPS-RPM with local topology preservation algorithm (TPS-RPM-LTP) was evaluated using four numerically simulated synthetic bladders having known deformations, a custom-made porcine bladder phantom embedded with twenty one fiducial markers, and 29 fractional computed tomography (CT) images from seven cervical cancer patients. Results show that TPS-RPM-LTP achieved excellent geometric accuracy with landmark residual distance error (RDE) of 0.7  ±  0.3 mm for the numerical synthetic data with different scales of bladder deformation and structure complexity, and 3.7  ±  1.8 mm and 1.6  ±  0.8 mm for the porcine bladder phantom with large and small deformation, respectively. The RDE accuracy of the urethral orifice landmarks in patient bladders was 3.7  ±  2.1 mm. When compared to the original TPS-RPM, the TPS-RPM-LTP improved landmark matching by reducing landmark RDE by 50  ±  19%, 37  ±  11% and 28  ±  11% for the synthetic, porcine phantom and the patient bladders, respectively. This was achieved with a computational time of less than 15 s in all cases

  16. A non-rigid point matching method with local topology preservation for accurate bladder dose summation in high dose rate cervical brachytherapy

    NASA Astrophysics Data System (ADS)

    Chen, Haibin; Zhong, Zichun; Liao, Yuliang; Pompoš, Arnold; Hrycushko, Brian; Albuquerque, Kevin; Zhen, Xin; Zhou, Linghong; Gu, Xuejun

    2016-02-01

    GEC-ESTRO guidelines for high dose rate cervical brachytherapy advocate the reporting of the D2cc (the minimum dose received by the maximally exposed 2cc volume) to organs at risk. Due to large interfractional organ motion, reporting of accurate cumulative D2cc over a multifractional course is a non-trivial task requiring deformable image registration and deformable dose summation. To efficiently and accurately describe the point-to-point correspondence of the bladder wall over all treatment fractions while preserving local topologies, we propose a novel graphic processing unit (GPU)-based non-rigid point matching algorithm. This is achieved by introducing local anatomic information into the iterative update of correspondence matrix computation in the ‘thin plate splines-robust point matching’ (TPS-RPM) scheme. The performance of the GPU-based TPS-RPM with local topology preservation algorithm (TPS-RPM-LTP) was evaluated using four numerically simulated synthetic bladders having known deformations, a custom-made porcine bladder phantom embedded with twenty one fiducial markers, and 29 fractional computed tomography (CT) images from seven cervical cancer patients. Results show that TPS-RPM-LTP achieved excellent geometric accuracy with landmark residual distance error (RDE) of 0.7  ±  0.3 mm for the numerical synthetic data with different scales of bladder deformation and structure complexity, and 3.7  ±  1.8 mm and 1.6  ±  0.8 mm for the porcine bladder phantom with large and small deformation, respectively. The RDE accuracy of the urethral orifice landmarks in patient bladders was 3.7  ±  2.1 mm. When compared to the original TPS-RPM, the TPS-RPM-LTP improved landmark matching by reducing landmark RDE by 50  ±  19%, 37  ±  11% and 28  ±  11% for the synthetic, porcine phantom and the patient bladders, respectively. This was achieved with a computational time of less than 15 s in all cases

  17. Influence of additives on the increase of the heating value of Bayah's coal with upgrading brown coal (UBC) method

    NASA Astrophysics Data System (ADS)

    Heriyanto, Heri; Widya Ernayati, K.; Umam, Chairul; Margareta, Nita

    2015-12-01

    UBC (upgrading brown coal) is a method of improving the quality of coal by using oil as an additive. Through processing in the oil media, not just the calories that increase, but there is also water repellent properties and a decrease in the tendency of spontaneous combustion of coal products produced. The results showed a decrease in the water levels of natural coal bayah reached 69%, increase in calorific value reached 21.2%. Increased caloric value and reduced water content caused by the water molecules on replacing seal the pores of coal by oil and atoms C on the oil that is bound to increase the percentage of coal carbon. As a result of this experiment is, the produced coal has better calorific value, the increasing of this new calorific value up to 23.8% with the additive waste lubricant, and the moisture content reduced up to 69.45%.

  18. Effect of Ag nanowire addition into nanoparticle paste on the conductivity of Ag patterns printed by gravure offset method.

    PubMed

    Ok, Ki-Hun; Lee, Chan-Jae; Kwak, Min-Gi; Choi, Duck-Kyun; Kim, Kwang-Seok; Jung, Seung-Boo; Kim, Jong-Woong

    2014-11-01

    This paper focuses on the effect of Ag nanowire addition into a commercial Ag nanopaste and the printability evaluation of the mixed paste by the gravure offset printing methodology. Ag nanowires were synthesized by a modified polyol method, and a small amount of them was added into a commercial metallic paste based on Ag nanoparticles of 50 nm in diameter. Two annealing temperatures were selected for comparison, and electrical conductivity was measured by four point probe method. As a result, the hybrid mixture could be printed by the gravure offset method for patterning fine lines up to 15 μm width with sharp edges and scarce spreading. The addition of the Ag nanowires was significantly efficient for enhancement of electrical conductivity of the printed lines annealed at a low temperature (150 degrees C), while the effect was somewhat diluted in case of high temperature annealing (200 degrees C). The experimental results were discussed with the conduction mechanism in the printed conductive circuits with a schematic description of the electron flows in the printed lines.

  19. The effect of three different methods of adding O2 additive on O concentration of atmospheric pressure plasma jets (APPJs)

    NASA Astrophysics Data System (ADS)

    Yue, Y.; Xian, Y.; Pei, X.; Lu, X.

    2016-12-01

    In order to maximize the O concentration generated by the atmospheric pressure plasma jets (APPJs), several different methods of adding O2 additive to working gas have been proposed. However, it is not clear, which method is capable of generating the highest concentration of O atom. In this paper, the concentration of O atoms in an APPJs by adding O2 to (1) the working gas, to (2) the downstream inside the tube, and (3) to the shielding gas is investigated by two-photon absorption laser-induced fluorescence spectrometry. The results clearly demonstrate that the highest O density is achieved when 1.5% of O2 is added to the working gas rather than the other two methods. In other words, the most effective way to generate O atoms is by premixing O2 with the working gas. Further investigation suggests that O atoms are mainly generated around the electrode region, where the electric field is highest. In addition, when O2 is added to the working gas, if in the meantime extra O2 is added to the downstream inside the tube, a significant decrease of O density is observed.

  20. [Analysis of lead in unknown samples based on the standard addition method using laser induced breakdown spectroscopy].

    PubMed

    Fang, Li; Zhao, Nan-jing; Meng, De-shuo; Yuan, Jing; Tang, Jie; Wang, Yin; Yu, Yang; Ma, Ming-jun; Hu, Li; Zhang, Da-hai; Xiao, Xue; Wang, Yu; Liu, Jian-guo; Liu, Wen-qing

    2015-01-01

    The standard addition method with laser induced breakdown spectroscopy was used to analyze an unknown sample taken from a lead battery factory. the matrix influence on the results was effectively avoided when the external or internal standard method was used, and the pretreatment of samples was simple and quick. The Nd ' YAG pulse laser with wavelength 1 064 nm was used as the excitation source. The echelle spectroscopy with high resolution and wide spectral range was used as the spectral separation device, and the intensified charge coupled device (ICCD) as the spectral detection device in the experiment. The characteristic line at 405. 78 nrn was chosen as the analysis line to measure Pb concentration. Fe I : 404. 58 line was chosen as the internal standard. Pre-experiment was carried out to confirm the appropriate condition. Under the laser energy of 128. 5 mJ, the delay time of 2. 5 tps, and the gate width of 3 ps, it was determined that with the addition of Pb to the sample in the range of 0 and 25 000 mg . kg-1, there wasn't self-absorption. There was a good linear relationship between the intensity of the spectral line of 405. 78 nm and the addition of Pb. The appropriate concentration of Pb added into the sample for analysis was determined by this series of samples. On this basis, four samples were prepared with three parallel samples for each sample in order to verify the repeatability and reliability of the method, i. e. 5 000, 10 000, 15 000, 20 000 mg . kg-1 Pb was added into the original sample. The results were compared with the result of ICP-MS. The twelve samples' relative errors were between -24. 6% and 17. 6%. The average result was 43 069 mg . kg-1 with the relative error -2. 44%.

  1. Developing porous ceramics on the base of zirconia oxide with thin and permeable pores by crystallization of organic additive method

    NASA Astrophysics Data System (ADS)

    Kamyshnaya, K. S.; Khabas, T. A.

    2016-11-01

    In this paper porous ceramics on the base of ZrO2 nanopowders and micropowders has been developed by freeze-casting method. A zirconia/carbamide slurry was frozen in mold and dehydrated in CaCl2 at room temperature. This simple process enabled the formation of porous ceramics with highly aligned pores as a replica of the carbamide crystals. The samples showed higher porosity of 47.9%. In addition, these materials could be used as membrane for air cleaning.

  2. Net analyte signal standard addition method (NASSAM) as a novel spectrofluorimetric and spectrophotometric technique for simultaneous determination, application to assay of melatonin and pyridoxine

    NASA Astrophysics Data System (ADS)

    Asadpour-Zeynali, Karim; Bastami, Mohammad

    2010-02-01

    In this work a new modification of the standard addition method called "net analyte signal standard addition method (NASSAM)" is presented for the simultaneous spectrofluorimetric and spectrophotometric analysis. The proposed method combines the advantages of standard addition method with those of net analyte signal concept. The method can be applied for the determination of analyte in the presence of known interferents. The accuracy of the predictions against H-point standard addition method is not dependent on the shape of the analyte and interferent spectra. The method was successfully applied to simultaneous spectrofluorimetric and spectrophotometric determination of pyridoxine (PY) and melatonin (MT) in synthetic mixtures and in a pharmaceutical formulation.

  3. Quantification of rat retinal growth and vascular population changes after single and split doses of proton irradiation: translational study using stereology methods

    NASA Technical Reports Server (NTRS)

    Mao, Xiao W.; Archambeau, John O.; Kubinova, Lucie; Boyle, Soames; Petersen, Georgia; Grove, Roger; Nelson, G. A. (Principal Investigator)

    2003-01-01

    This study quantified architectural and population changes in the rat retinal vasculature after proton irradiation using stereology. A 100 MeV conformal proton beam delivered 8, 14, 20 and 28 Gy as single and split doses to the whole eye. The vascular networks were prepared from retinal digests. Stereological methods were used to obtain the area of the retina and unbiased estimates of microvessel/artery/vein endothelial, pericyte and smooth muscle population, and vessel length. The retinal area increased progressively in the unirradiated, age-matched controls and in the retinas irradiated with 8 and 14 Gy, indicating uniform progressive retinal growth. No growth occurred after 20 and 28 Gy. Regression analysis of total endothelial cell number in all vessels (arteries, veins and capillaries) after irradiation documented a progressive time- and dose-dependent cell loss occurring over 15 to 24 months. The difference from controls was significant (P<0.01) after 28 Gy given in single and split doses and after 20 Gy given as a split dose (P<0.05). Total vessel length in microvessel was significantly shortened at 20 and 28 Gy compared to that of controls (P<0.05). No evident dose recovery was observed in the endothelial populations after split doses. At 10 Gy, the rate of endothelial cell loss, a dose parameter used to characterize the time- and dose-dependent loss of the endothelial population, was doubled.

  4. Effects on nutrient digestion of wheat processing and methods of tallow addition to the diets of lactating dairy cows.

    PubMed

    Espindola, M S; DePeters, E J; Fadel, J G; Zinn, R A; Perez-Monti, H

    1997-06-01

    Five multiparous Holstein cows in midlactation that were fitted with ruminal and duodenal cannulas were used in a 3 x 5 incomplete Latin square. The objective of this study was to examine the effects on nutrient digestion of wheat processing and method of tallow addition to the diets of lactating dairy cows. Diets consisted of 45% forage and 55% concentrate, and each diet contained 20% wheat and 2% tallow (as-fed basis). Treatments were dry-rolled wheat with tallow added to the concentrate, steam-rolled wheat with tallow added to the concentrate, and steam-rolled wheat with tallow added first to the wheat. The dry matter intake; digestion of starch, fiber, and fatty acids; ammonia N concentration; and molar proportions of volatile fatty acids in ruminal fluid were not affected by treatments. The apparent digestibility in the total tract of organic matter and nitrogenous compounds was significantly higher for the steam-rolled treatment with tallow added first to the wheat. Mean ruminal fluid pH was similar across treatments; however, cows fed the diet containing steam-rolled wheat with tallow added first to the wheat had the smallest pH change from 0 to 2 h postfeeding. Milk yield did not differ, regardless of cow diet. Method of tallow addition had marked effects on the apparent digestibility of organic matter and N in the total tract of lactating dairy cows.

  5. Quantitative mass spectrometric analysis of dipeptides in protein hydrolysate by a TNBS derivatization-aided standard addition method.

    PubMed

    Hanh, Vu Thi; Kobayashi, Yutaro; Maebuchi, Motohiro; Nakamori, Toshihiro; Tanaka, Mitsuru; Matsui, Toshiro

    2016-01-01

    The aim of this study was to establish, through a standard addition method, a convenient quantification assay for dipeptides (GY, YG, SY, YS, and IY) in soybean hydrolysate using 2,4,6-trinitrobenzene sulfonate (TNBS) derivatization-aided LC-TOF-MS. Soybean hydrolysate samples (25.0 mg mL(-1)) spiked with target standards were subjected to TNBS derivatization. Under the optimal LC-MS conditions, five target dipeptides derivatized with TNBS were successfully detected. Examination of the standard addition curves, with a correlation coefficient of r(2) > 0.979, provided a reliable quantification of the target dipeptides, GY, YG, SY, YS, and IY, in soybean hydrolysate to be 424 ± 20, 184 ± 9, 2188 ± 199, 327 ± 16, and 2211 ± 133 μg g(-1) of hydrolysate, respectively. The proposed LC-MS assay is a reliable and convenient assay method, with no interference from matrix effects in hydrolysate, and with no requirement for the use of an isotope labeled internal standard.

  6. A method of analyzing nonstationary ionic channel current fluctuations in the presence of an additive measurement noise.

    PubMed

    Mino, H

    1993-03-01

    A method of estimating the parameters of nonstationary ionic channel current fluctuations (NST-ICF's) in the presence of an additive measurement noise is proposed. The case is considered in which the sample records of NST-ICT's corrupted by the measurement noise are available for estimation, where the experiment can be repeated many times to calculate the statistics of noisy NST-ICF's. The conventional second-order regression model expressed in terms of the mean and variance of noisy NST-ICF's is derived theoretically, assuming that NST-ICF's are binomially distributed. Since the coefficients of the regression model are explicitly related to not only the parameters of NST-ICF's but also the measurement noise component, the parameters of NST-ICF's that are of interest can be estimated without interference from the additive measurement noise by identifying the regression coefficients. Furthermore, the accuracy of the parameter estimates is theoretically evaluated using the error-covariance matrix of the regression coefficients. The validity and effectiveness of the proposed method are demonstrated in a Monte Carlo simulation in which a fundamental kinetic scheme of Na+ channels is treated as a specific example.

  7. 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

  8. Sequential multi-nuclide emission rate estimation method based on gamma dose rate measurement for nuclear emergency management.

    PubMed

    Zhang, Xiaole; Raskob, Wolfgang; Landman, Claudia; Trybushnyi, Dmytro; Li, Yu

    2017-03-05

    In case of a nuclear accident, the source term is typically not known but extremely important for the assessment of the consequences to the affected population. Therefore the assessment of the potential source term is of uppermost importance for emergency response. A fully sequential method, derived from a regularized weighted least square problem, is proposed to reconstruct the emission and composition of a multiple-nuclide release using gamma dose rate measurement. The a priori nuclide ratios are incorporated into the background error covariance (BEC) matrix, which is dynamically augmented and sequentially updated. The negative estimations in the mathematical algorithm are suppressed by utilizing artificial zero-observations (with large uncertainties) to simultaneously update the state vector and BEC. The method is evaluated by twin experiments based on the JRodos system. The results indicate that the new method successfully reconstructs the emission and its uncertainties. Accurate a priori ratio accelerates the analysis process, which obtains satisfactory results with only limited number of measurements, otherwise it needs more measurements to generate reasonable estimations. The suppression of negative estimation effectively improves the performance, especially for the situation with poor a priori information, where it is more prone to the generation of negative values.

  9. Standard addition method for the determination of pharmaceutical residues in drinking water by SPE-LC-MS/MS.

    PubMed

    Cimetiere, Nicolas; Soutrel, Isabelle; Lemasle, Marguerite; Laplanche, Alain; Crocq, André

    2013-01-01

    The study of the occurrence and fate of pharmaceutical compounds in drinking or waste water processes has become very popular in recent years. Liquid chromatography with tandem mass spectrometry is a powerful analytical tool often used to determine pharmaceutical residues at trace level in water. However, many steps may disrupt the analytical procedure and bias the results. A list of 27 environmentally relevant molecules, including various therapeutic classes and (cardiovascular, veterinary and human antibiotics, neuroleptics, non-steroidal anti-inflammatory drugs, hormones and other miscellaneous pharmaceutical compounds), was selected. In this work, a method was developed using ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) and solid-phase extraction to determine the concentration of the 27 targeted pharmaceutical compounds at the nanogram per litre level. The matrix effect was evaluated from water sampled at different treatment stages. Conventional methods with external calibration and internal standard correction were compared with the standard addition method (SAM). An accurate determination of pharmaceutical compounds in drinking water was obtained by the SAM associated with UPLC-MS/MS. The developed method was used to evaluate the occurrence and fate of pharmaceutical compounds in some drinking water treatment plants in the west of France.

  10. Simultaneously Enhanced Efficiency and Stability of Polymer Solar Cells by Employing Solvent Additive and Upside-down Drying Method.

    PubMed

    Sun, Qianqian; Zhang, Fujun; An, Qiaoshi; Zhang, Miao; Ma, Xiaoling; Zhang, Jian

    2017-03-15

    The morphology of active layer plays an important role in determining the power conversion efficiency (PCE) and stability of polymer solar cells (PSCs), which strongly depend on the dynamic drying process of active layer. In this work, an efficient and universal method was developed to let active layer undergo upside-down drying process in a covered glass Petri dish. For the PSCs based on PTB7-Th:PC71BM, the champion PCEs were improved from 8.58% to 9.64% by mixing 3 vol % 1,8-di-iodooctane and further to 10.30% by employing upside-down drying method. The enhanced PCEs of PSCs with active layers undergoing upside-down drying process are mainly attributed to the optimized vertical phase separation, the more ordered and tightly packed π-π stacking of polymer molecules. Meanwhile, PC71BM molecules can be frozen in more ordered and tightly packed π-π stacking polymer network, which lead to the enhanced stability of PSCs. The universality of upside-down drying method can be solidly confirmed from PSCs with PTB7:PC71BM, PffBT4T-2OD:PC71BM, or PBDT-TS1:PC71BM as active layers, respectively. The molecular packing and phase separation of blend films with different solvent additives and drying methods were investigated by grazing incidence X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy.

  11. 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.

  12. SU-C-BRD-07: Three-Dimensional Dose Reconstruction in the Presence of Inhomogeneities Using Fast EPID-Based Back-Projection Method

    SciTech Connect

    Ren, Q; Cao, R; Pei, X; Wang, H; Hu, L

    2015-06-15

    Purpose: Three-dimensional dose verification can detect errors introduced by the treatment planning system (TPS) or differences between planned and delivered dose distribution during the treatment. The aim of the study is to extend a previous in-house developed three-dimensional dose reconstructed model in homogeneous phantom to situtions in which tissue inhomogeneities are present. Methods: The method was based on the portal grey images from an electronic portal imaging device (EPID) and the relationship between beamlets and grey-scoring voxels at the position of the EPID. The relationship was expressed in the form of grey response matrix that was quantified using thickness-dependence scatter kernels determined by series of experiments. From the portal grey-value distribution information measured by the EPID the two-dimensional incident fluence distribution was reconstructed based on the grey response matrix using a fast iterative algorithm. The accuracy of this approach was verified using a four-field intensity-modulated radiotherapy (IMRT) plan for the treatment of lung cancer in anthopomorphic phantom. Each field had between twenty and twenty-eight segments and was evaluated by comparing the reconstructed dose distribution with the measured dose. Results: The gamma-evaluation method was used with various evaluation criteria of dose difference and distance-to-agreement: 3%/3mm and 2%/2 mm. The dose comparison for all irradiated fields showed a pass rate of 100% with the criterion of 3%/3mm, and a pass rate of higher than 92% with the criterion of 2%/2mm. Conclusion: Our experimental results demonstrate that our method is capable of accurately reconstructing three-dimensional dose distribution in the presence of inhomogeneities. Using the method, the combined planning and treatment delivery process is verified, offing an easy-to-use tool for the verification of complex treatments.

  13. Practical dosimetry methods for the determination of effective skin and breast dose for a modern CT system, incorporating partial irradiation and prospective cardiac gating

    PubMed Central

    Loader, R J; Gosling, O; Roobottom, C; Morgan-Hughes, G; Rowles, N

    2012-01-01

    Objective For CT coronary angiography (CTCA), a generic chest conversion factor returns a significant underestimate of effective dose. The aim of this manuscript is to communicate new dosimetry methods to calculate weighted CT dose index (CTDIw), effective dose, entrance surface dose (ESD) and organ dose to the breast for prospectively gated CTCA. Methods CTDIw in 32 cm diameter Perspex phantom was measured using an adapted technique, accounting for the segmented scan characteristic. Gafchromic XRCT film (International Speciality Products, New Jersey, NJ) was used to measure the distribution and magnitude of ESD. Breast dose was measured using high sensitivity metal oxide semiconductor field-effect transistors and compared to the computer based imaging performance assessment of CT scanners (ImPACT) dosimetry calculations. Results For a typical cardiac scan the mean ESD remained broadly constant (7–9 mGy) when averaged over the circumference of the Perspex phantom. Typical absorbed dose to the breast with prospectively gated protocols was within the range 2–15 mGy. The subsequent lifetime attributable risk (LAR) of cancer incidence to the breast was found at 0.01–0.06 for a 20-year-old female. This compares favourably to 100 mGy (LAR ∼0.43) for a retrospectively gated CTCA. Conclusions Care must be taken when considering radiation dosimetry associated with prospectively gated scanning for CTCA and a method has been conveyed to account for this. Breast doses for prospectively gated CTCA are an order of magnitude lower than retrospectively gated scans. Optimisation of cardiac protocols is expected to show further dose reduction. PMID:21896660

  14. Optimal Dose and Method of Administration of Intravenous Insulin in the Management of Emergency Hyperkalemia: A Systematic Review

    PubMed Central

    Harel, Ziv; Kamel, Kamel S.

    2016-01-01

    Background and Objectives Hyperkalemia is a common electrolyte disorder that can result in fatal cardiac arrhythmias. Despite the importance of insulin as a lifesaving intervention in the treatment of hyperkalemia in an emergency setting, there is no consensus on the dose or the method (bolus or infusion) of its administration. Our aim was to review data in the literature to determine the optimal dose and route of administration of insulin in the management of emergency hyperkalemia. Design, Setting, Participants, & Measurements We searched several databases from their date of inception through February 2015 for eligible articles published in any language. We included any study that reported on the use of insulin in the management of hyperkalemia. Results We identified eleven studies. In seven studies, 10 units of regular insulin was administered (bolus in five studies, infusion in two studies), in one study 12 units of regular insulin was infused over 30 minutes, and in three studies 20 units of regular insulin was infused over 60 minutes. The majority of included studies were biased. There was no statistically significant difference in mean decrease in serum potassium (K+) concentration at 60 minutes between studies in which insulin was administered as an infusion of 20 units over 60 minutes and studies in which 10 units of insulin was administered as a bolus (0.79±0.25 mmol/L versus 0.78±0.25 mmol/L, P = 0.98) or studies in which 10 units of insulin was administered as an infusion (0.79±0.25 mmol/L versus 0.39±0.09 mmol/L, P = 0.1). Almost one fifth of the study population experienced an episode of hypoglycemia. Conclusion The limited data available in the literature shows no statistically significant difference between the different regimens of insulin used to acutely lower serum K+ concentration. Accordingly, 10 units of short acting insulin given intravenously may be used in cases of hyperkalemia. Alternatively, 20 units of short acting insulin may be

  15. 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.

  16. Accuracy of effective dose estimation in personal dosimetry: a comparison between single-badge and double-badge methods and the MOSFET method.

    PubMed

    Januzis, Natalie; Belley, Matthew D; Nguyen, Giao; Toncheva, Greta; Lowry, Carolyn; Miller, Michael J; Smith, Tony P; Yoshizumi, Terry T

    2014-05-01

    The purpose of this study was three-fold: (1) to measure the transmission properties of various lead shielding materials, (2) to benchmark the accuracy of commercial film badge readings, and (3) to compare the accuracy of effective dose (ED) conversion factors (CF) of the U.S. Nuclear Regulatory Commission methods to the MOSFET method. The transmission properties of lead aprons and the accuracy of film badges were studied using an ion chamber and monitor. ED was determined using an adult male anthropomorphic phantom that was loaded with 20 diagnostic MOSFET detectors and scanned with a whole body CT protocol at 80, 100, and 120 kVp. One commercial film badge was placed at the collar and one at the waist. Individual organ doses and waist badge readings were corrected for lead apron attenuation. ED was computed using ICRP 103 tissue weighting factors, and ED CFs were calculated by taking the ratio of ED and badge reading. The measured single badge CFs were 0.01 (±14.9%), 0.02 (±9.49%), and 0.04 (±15.7%) for 80, 100, and 120 kVp, respectively. Current regulatory ED CF for the single badge method is 0.3; for the double-badge system, they are 0.04 (collar) and 1.5 (under lead apron at the waist). The double-badge system provides a better coefficient for the collar at 0.04; however, exposure readings under the apron are usually negligible to zero. Based on these findings, the authors recommend the use of ED CF of 0.01 for the single badge system from 80 kVp (effective energy 50.4 keV) data.

  17. GPU-Accelerated Monte Carlo Electron Transport Methods: Development and Application for Radiation Dose Calculations Using Six GPU cards

    NASA Astrophysics Data System (ADS)

    Su, Lin; Du, Xining; Liu, Tianyu; Xu, X. George

    2014-06-01

    An electron-photon coupled Monte Carlo code ARCHER - Accelerated Radiation-transport Computations in Heterogeneous EnviRonments - is being developed at Rensselaer Polytechnic Institute as a software testbed for emerging heterogeneous high performance computers that utilize accelerators such as GPUs. This paper presents the preliminary code development and the testing involving radiation dose related problems. In particular, the paper discusses the electron transport simulations using the class-II condensed history method. The considered electron energy ranges from a few hundreds of keV to 30 MeV. For photon part, photoelectric effect, Compton scattering and pair production were modeled. Voxelized geometry was supported. A serial CPU code was first written in C++. The code was then transplanted to the GPU using the CUDA C 5.0 standards. The hardware involved a desktop PC with an Intel Xeon X5660 CPU and six NVIDIA Tesla™ M2090 GPUs. The code was tested for a case of 20 MeV electron beam incident perpendicularly on a water-aluminum-water phantom. The depth and later dose profiles were found to agree with results obtained from well tested MC codes. Using six GPU cards, 6x106 electron histories were simulated within 2 seconds. In comparison, the same case running the EGSnrc and MCNPX codes required 1645 seconds and 9213 seconds, respectively. On-going work continues to test the code for different medical applications such as radiotherapy and brachytherapy.

  18. Early Dose Response to Yttrium-90 Microsphere Treatment of Metastatic Liver Cancer by a Patient-Specific Method Using Single Photon Emission Computed Tomography and Positron Emission Tomography

    SciTech Connect

    Campbell, Janice M. Wong, C. Oliver; Muzik, Otto; Marples, Brian; Joiner, Michael; Burmeister, Jay

    2009-05-01

    Purpose: To evaluate a patient-specific single photon emission computed tomography (SPECT)-based method of dose calculation for treatment planning of yttrium-90 ({sup 90}Y) microsphere selective internal radiotherapy (SIRT). Methods and Materials: Fourteen consecutive {sup 90}Y SIRTs for colorectal liver metastasis were retrospectively analyzed. Absorbed dose to tumor and normal liver tissue was calculated by partition methods with two different tumor/normal liver vascularity ratios: an average 3:1 and a patient-specific ratio derived from pretreatment technetium-99m macroaggregated albumin SPECT. Tumor response was quantitatively evaluated from fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography scans. Results: Positron emission tomography showed a significant decrease in total tumor standardized uptake value (average, 52%). There was a significant difference in the tumor absorbed dose between the average and specific methods (p = 0.009). Response vs. dose curves fit by linear and linear-quadratic modeling showed similar results. Linear fit r values increased for all tumor response parameters with the specific method (+0.20 for mean standardized uptake value). Conclusion: Tumor dose calculated with the patient-specific method was more predictive of response in liver-directed {sup 90}Y SIRT.

  19. A handheld mid-infrared methane sensor using a dual-step differential method for additive/multiplicative noise suppression

    NASA Astrophysics Data System (ADS)

    Zheng, Yue; Dang, Peipei; Zheng, Chuantao; Ye, Weilin; Wang, Yiding

    2016-11-01

    A miniature mid-infrared (mid-IR) methane (CH4) sensor system was developed by employing a wide-band wire-source and a semi-ellipsoid multi-pass gas cell. A dual-step differential method instead of the traditional one-step differential method was adopted by this sensor to tune measuring range/zero point and to suppress the additive/multiplicative noise. This method included a first subtraction operation between the two output signals (including a detection signal and a reference signal) from the dual-channel detector and a second subtraction operation on the amplitudes of the first-subtraction signal and the reference signal, followed by a ratio operation between the amplitude of the second-subtraction signal and the reference signal. Detailed experiments were performed to assess the performance of the sensor system. The detection range is 0-50 k ppm, and as the concentration gets larger than 12 k ppm, the relative detection error falls into the range of -3% to +3%. The Allan deviation is about 4.65 ppm with an averaging time of 1 s, and such value can be further improved to 0.45 ppm with an averaging time of 124 s. Due to the cost-effective incandescence wire-source, the small-size ellipsoid multi-pass gas cell and the miniature structure of the sensor, the developed standalone device shows potential applications of CH4 detection under coal-mine environment.

  20. Dose Estimation for a Study of Nuclear Workers in France, the United Kingdom and the United States of America: Methods for the International Nuclear Workers Study (INWORKS)

    PubMed Central

    Thierry-Chef, I.; Richardson, D. B.; Daniels, R. D.; Gillies, M.; Hamra, G. B.; Haylock, R.; Kesminiene, A.; Laurier, D.; Leuraud, K.; Moissonnier, M.; O'Hagan, J.; Schubauer-Berigan, M. K.; Cardis, E.

    2016-01-01

    In the framework of the International Nuclear Workers Study conducted in France, the UK and the U.S. (INWORKS), updated and expanded methods were developed to convert recorded doses of ionizing radiation to estimates of organ doses or individual personal dose equivalent [Hp(10)] for a total number of 308,297 workers, including 40,035 women. This approach accounts for differences in dosimeter response to predominant workplace energy and geometry of exposure and for the recently published ICRP report on dose coefficients for men and women separately. The overall mean annual individual personal dose equivalent, including zero doses, is 1.73 mSv [median = 0.42; interquartile range (IQR): 0.07, 1.59]. Associated individual organ doses were estimated. INWORKS includes workers who had potential for exposure to neutrons. Therefore, we analyzed neutron dosimetry data to identify workers potentially exposed to neutrons. We created a time-varying indicator for each worker, classifying them according to whether they had a positive recorded neutron dose and if so, whether their neutron dose ever exceeded 10% of their total external penetrating radiation dose. The number of workers flagged as being exposed to neutrons was 13% for the full cohort, with 15% of the cohort in France, 12% of the cohort in the UK and 14% in the U.S. We also used available information on in vivo and bioassay monitoring to identify workers with known depositions or suspected internal contaminations. As a result of this work, information is now available that will allow various types of sensitivity analyses. PMID:26010707

  1. Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism: Current status and recommendations for clinical implementation

    SciTech Connect

    Beaulieu, Luc; Carlsson Tedgren, Asa; Carrier, Jean-Francois; and others

    2012-10-15

    the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim recommendations are made and potential areas of research are identified. Application of TG-186 guidance should retain practice uniformity in transitioning from the TG-43 to the MBDCA approach.

  2. Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism: current status and recommendations for clinical implementation.

    PubMed

    Beaulieu, Luc; Carlsson Tedgren, Asa; Carrier, Jean-Francois; Davis, Stephen D; Mourtada, Firas; Rivard, Mark J; Thomson, Rowan M; Verhaegen, Frank; Wareing, Todd A; Williamson, Jeffrey F

    2012-10-01

    to the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim recommendations are made and potential areas of research are identified. Application of TG-186 guidance should retain practice uniformity in transitioning from the TG-43 to the MBDCA approach.

  3. Effect of Gamma Irradiation on Cement Composites Observed with XRD and SEM Methods in the Range of Radiation Dose 0-1409 MGy

    NASA Astrophysics Data System (ADS)

    Łowińska-Kluge, A.; Piszora, P.

    2008-08-01

    The effect of gamma radiation in the range of 0-1409 MGy on the structure of a new mineral additive to cement based composites was investigated in the perspective of employing them as radioactive waste protection material. According to the authors knowledge, it is the first paper dealing with observations of the cement matrix, both pure and modified, treated with so giant radiation dose. The absorption of gamma radiation modifies the morphology of the additive grains, causes decomposition of cement hydrates and clinker relicts in cement paste containing the additive at twice higher radiation dose than that inducing the decomposition of the reference pure cement paste and the cement paste containing pozzolane additives.

  4. An optimized regulating method for composting phosphorus fractions transformation based on biochar addition and phosphate-solubilizing bacteria inoculation.

    PubMed

    Wei, Yuquan; Zhao, Yue; Wang, Huan; Lu, Qian; Cao, Zhenyu; Cui, Hongyang; Zhu, Longji; Wei, Zimin

    2016-12-01

    The study was conducted to investigate the influence of biochar and/or phosphate-solubilizing bacteria (PSB) inoculants on microbial biomass, bacterial community composition and phosphorus (P) fractions during kitchen waste composting amended with rock phosphate (RP). There were distinct differences in the physic-chemical parameters, the proportion of P fractions and bacterial diversity in different treatments. The contribution of available P fractions increased during composting especially in the treatment with the addition of PSB and biochar. Redundancy analysis showed that bacterial compositions were significantly influenced by P content, inoculation and biochar. Variance partitioning further showed that synergy of inoculated PSB and indigenous bacterial communities and the joint effect between biochar and bacteria explained the largest two proportion of the variation in P fractions. Therefore, the combined application of PSB and biochar to improve the inoculation effect and an optimized regulating method were suggested based on the distribution of P fractions.

  5. Effect of olive mill waste addition on the properties of porous fired clay bricks using Taguchi method.

    PubMed

    Sutcu, Mucahit; Ozturk, Savas; Yalamac, Emre; Gencel, Osman

    2016-10-01

    Production of porous clay bricks lightened by adding olive mill waste as a pore making additive was investigated. Factors influencing the brick manufacturing process were analyzed by an experimental design, Taguchi method, to find out the most favorable conditions for the production of bricks. The optimum process conditions for brick preparation were investigated by studying the effects of mixture ratios (0, 5 and 10 wt%) and firing temperatures (850, 950 and 1050 °C) on the physical, thermal and mechanical properties of the bricks. Apparent density, bulk density, apparent porosity, water absorption, compressive strength, thermal conductivity, microstructure and crystalline phase formations of the fired brick samples were measured. It was found that the use of 10% waste addition reduced the bulk density of the samples up to 1.45 g/cm(3). As the porosities increased from 30.8 to 47.0%, the compressive strengths decreased from 36.9 to 10.26 MPa at firing temperature of 950 °C. The thermal conductivities of samples fired at the same temperature showed a decrease of 31% from 0.638 to 0.436 W/mK, which is hopeful for heat insulation in the buildings. Increasing of the firing temperature also affected their mechanical and physical properties. This study showed that the olive mill waste could be used as a pore maker in brick production.

  6. SU-F-18C-13: Low-Dose X-Ray CT Reconstruction Using a Hybrid First-Order Method

    SciTech Connect

    Liu, L; Lin, W; Jin, M

    2014-06-15

    Purpose: To develop a novel reconstruction method for X-ray CT that can lead to accurate reconstruction at significantly reduced dose levels combining low X-ray incident intensity and few views of projection data. Methods: The noise nature of the projection data at low X-ray incident intensity was modeled and accounted by the weighted least-squares (WLS) criterion. The total variation (TV) penalty was used to mitigate artifacts caused by few views of data. The first order primal-dual (FOPD) algorithm was used to minimize TV in image domain, which avoided the difficulty of the non-smooth objective function. The TV penalized WLS reconstruction was achieved by alternated FOPD TV minimization and projection onto convex sets (POCS) for data fidelity constraints. The proposed FOPD-POCS method was evaluated using the FORBILD jaw phantom and the real cadaver head CT data. Results: The quantitative measures, root mean square error (RMSE) and contrast-to-noise ratio (CNR), demonstrate the superior denoising capability of WLS over LS-based TV iterative reconstruction. The improvement of RMSE (WLS vs. LS) is 15%∼21% and that of CNR is 17%∼72% when the incident counts per ray are ranged from 1×10{sup 5} to 1×10{sup 3}. In addition, the TV regularization can accurately reconstruct images from about 50 views of the jaw phantom. The FOPD-POCS reconstruction reveals more structural details and suffers fewer artifacts in both the phantom and real head images. The FOPD-POCS method also shows fast convergence at low X-ray incident intensity. Conclusion: The new hybrid FOPD-POCS method, based on TV penalized WLS, yields excellent image quality when the incident X-ray intensity is low and the projection views are limited. The reconstruction is computationally efficient since the FOPD minimization of TV is applied only in the image domain. The characteristics of FOPD-POCS can be exploited to significantly reduce radiation dose of X-ray CT without compromising accuracy for diagnosis

  7. Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

    NASA Astrophysics Data System (ADS)

    Stavinoha, Joe N.

    The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al

  8. A square-wave adsorptive stripping voltammetric method for the determination of Amaranth, a food additive dye.

    PubMed

    Alghamdi, Ahmad H

    2005-01-01

    Square-wave adsorptive stripping voltammetric (AdSV) determinations of trace concentrations of the azo coloring agent Amaranth are described. The analytical methodology used was based on the adsorptive preconcentration of the dye on the hanging mercury drop electrode, followed by initiation of a negative sweep. In a pH 10 carbonate supporting electrolyte, Amaranth gave a well-defined and sensitive AdSV peak at -518 mV. The electroanalytical determination of this azo dye was found to be optimal in carbonate buffer (pH 10) under the following experimental conditions: accumulation time, 120 s; accumulation potential, 0.0 V; scan rate, 600 mV/s; pulse amplitude, 90 mV; and frequency, 50 Hz. Under these optimized conditions the AdSV peak current was proportional over the concentration range 1 x 10(-8)-1.1 x 10(-7) mol/L (r = 0.999) with a detection limit of 1.7 x 10(-9) mol/L (1.03 ppb). This analytical approach possessed enhanced sensitivity, compared with conventional liquid chromatography or spectrophotometry and it was simple and fast. The precision of the method, expressed as the relative standard deviation, was 0.23%, whereas the accuracy, expressed as the mean recovery, was 104%. Possible interferences by several substances usually present as food additive azo dyes (E110, E102), gelatin, natural and artificial sweeteners, preservatives, and antioxidants were also investigated. The developed electroanalyticals method was applied to the determination of Amaranth in soft drink samples, and the results were compared with those obtained by a reference spectrophotometric method. Statistical analysis (paired t-test) of these data showed that the results of the 2 methods compared favorably.

  9. Method to Calculate the Protamine Dose Necessary for Reversal of Heparin as a Function of Activated Clotting Time in Patients Undergoing Cardiac Surgery

    PubMed Central

    Cuenca, Javier Suárez; Diz, Pilar Gayoso; Sampedro, Francisco Gude; Zincke, J. Marcos Gómez; Acuña, Helena Rey; Fontanillo, M. Manuela Fontanillo

    2013-01-01

    Abstract: Activated clotting time (ACT) has been used to monitor coagulation and guide management of anticoagulation control in patients undergoing cardiac surgery for decades. However, reversal of heparin with protamine is typically empirically based on total heparin administered. Dose-related adverse effects of protamine are well described. The aim of this study was to evaluate a heparin reversal strategy based on calculation of the protamine dose based on ACT measurements. We present a method using a mathematical formula based on the dose–response line (1). To check the formula, we performed a retrospective observational cohort study of 177 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). The study group of 80 patients was administered the dose of protamine obtained using our formula, and the control group of 97 patients was administered the empirically calculated dose. The ACT returned to normal values in patients who were given doses of protamine that were calculated using our formula; all but two had a final ACT of 141. The application of the formula resulted in a significant reduction in the dose of protamine (p < .023). The formula we present is a valid method for calculating the dose of protamine necessary to neutralize heparin. This same method can be used working with a target ACT to adjust the dose of heparin. As a result of its functionality, it allows application on a daily basis standardizing the process. We believe that the formula we developed can be applied in all those procedures in which it is necessary to anticoagulate patients with heparin and later neutralization (cardiac surgery with or without CPB, vascular surgery, procedures of interventional cardiology, and extracorporeal depuration procedures). PMID:24649571

  10. High-density dental implants and radiotherapy planning: evaluation of effects on dose distribution using pencil beam convolution algorithm and Monte Carlo method.

    PubMed

    Çatli, Serap

    2015-09-01

    High atomic number and density of dental implants leads to major problems at providing an accurate dose distribution in radiotherapy and contouring tumors and organs caused by the artifact in head and neck tumors. The limits and deficiencies of the algorithms using in the treatment planning systems can lead to large errors in dose calculation, and this may adversely affect the patient's treatment. In the present study, four commercial dental implants were used: pure titanium, titanium alloy (Ti-6Al-4V), amalgam, and crown. The effects of dental implants on dose distribution are determined with two methods: pencil beam convolution (PBC) algorithm and Monte Carlo code for 6 MV photon beam. The central axis depth doses were calculated on the phantom for a source-skin distance (SSD) of 100 cm and a 10×10 cm2 field using both of algorithms. The results of Monte Carlo method and Eclipse TPS were compared to each other and to those previously reported. In the present study, dose increases in tissue at a distance of 2 mm in front of the dental implants were seen due to the backscatter of electrons for dental implants at 6 MV using the Monte Carlo method. The Eclipse treatment planning system (TPS) couldn't precisely account for the backscatter radiation caused by the dental prostheses. TPS underestimated the back scatter dose and overestimated the dose after the dental implants. The large errors found for TPS in this study are due to the limits and deficiencies of the algorithms. The accuracy of the PBC algorithm of Eclipse TPS was evaluated in comparison to Monte Carlo calculations in consideration of the recommendations of the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 65. From the comparisons of the TPS and Monte Carlo calculations, it is verified that the Monte Carlo simulation is a good approach to derive the dose distribution in heterogeneous media. PACS numbers: 87.55.K.

  11. High-density dental implants and radiotherapy planning: evaluation of effects on dose distribution using pencil beam convolution algorithm and Monte Carlo method.

    PubMed

    Çatli, Serap

    2015-09-08

    High atomic number and density of dental implants leads to major problems at providing an accurate dose distribution in radiotherapy and contouring tumors and organs caused by the artifact in head and neck tumors. The limits and deficiencies of the algorithms using in the treatment planning systems can lead to large errors in dose calculation, and this may adversely affect the patient's treatment. In the present study, four commercial dental implants were used: pure titanium, titanium alloy (Ti-6Al-4V), amalgam, and crown. The effects of dental implants on dose distribution are determined with two methods: pencil beam convolution (PBC) algorithm and Monte Carlo code for 6 MV photon beam. The central axis depth doses were calculated on the phantom for a source-skin distance (SSD) of 100 cm and a 10 × 10 cm2 field using both of algorithms. The results of Monte Carlo method and Eclipse TPS were compared to each other and to those previously reported. In the present study, dose increases in tissue at a distance of 2 mm in front of the dental implants were seen due to the backscatter of electrons for dental implants at 6 MV using the Monte Carlo method. The Eclipse treatment planning system (TPS) couldn't precisely account for the backscatter radiation caused by the dental prostheses. TPS underestimated the back scatter dose and overestimated the dose after the dental implants. The large errors found for TPS in this study are due to the limits and deficiencies of the algorithms. The accuracy of the PBC algorithm of Eclipse TPS was evaluated in comparison to Monte Carlo calculations in consideration of the recommendations of the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 65. From the comparisons of the TPS and Monte Carlo calculations, it is verified that the Monte Carlo simulation is a good approach to derive the dose distribution in heterogeneous media.

  12. Normal tissue complication probability (NTCP) modelling using spatial dose metrics and machine learning methods for severe acute oral mucositis resulting from head and neck radiotherapy

    PubMed Central

    Dean, Jamie A; Wong, Kee H; Welsh, Liam C; Jones, Ann-Britt; Schick, Ulrike; Newbold, Kate L; Bhide, Shreerang A; Harrington, Kevin J; Nutting, Christopher M; Gulliford, Sarah L

    2016-01-01

    Background and Purpose Severe acute mucositis commonly results from head and neck (chemo)radiotherapy. A predictive model of mucositis could guide clinical decision-making and inform treatment planning. We aimed to generate such a model using spatial dose metrics and machine learning. Material and Methods Predictive models of severe acute mucositis were generated using radiotherapy dose (dose-volume and spatial dose metrics) and clinical data. Penalised logistic regression, support vector classification and random forest classification (RFC) models were generated and compared. Internal validation was performed (with 100-iteration cross-validation), using multiple metrics, including area under the receiver operating characteristic curve (AUC) and calibration slope, to assess performance. Associations between covariates and severe mucositis were explored using the models. Results The dose-volume-based models (standard) performed equally to those incorporating spatial information. Discrimination was similar between models, but the RFCstandard had the best calibration. The mean AUC and calibration slope for this model were 0.71 (s.d.=0.09) and 3.9 (s.d.=2.2), respectively. The volumes of oral cavity receiving intermediate and high doses were associated with severe mucositis. Conclusions The RFCstandard model performance is modest-to-good, but should be improved, and requires external validation. Reducing the volumes of oral cavity receiving intermediate and high doses may reduce mucositis incidence. PMID:27240717

  13. Offsite radiation doses from Hanford Operations for the years 1983 through 1987: A comparison of results calculated by two methods

    SciTech Connect

    Soldat, J.K.

    1989-10-01

    This report compares the results of the calculation of potential radiation doses to the public by two different environmental dosimetric systems for the years 1983 through 1987. Both systems project the environmental movement of radionuclides released with effluents from Hanford operations; their concentrations in air, water, and foods; the intake of radionuclides by ingestion and inhalation; and, finally, the potential radiation doses from radionuclides deposited in the body and from external sources. The first system, in use for the past decade at Hanford, calculates radiation doses in terms of 50-year cumulative dose equivalents to body organs and to the whole body, based on the methodology defined in ICRP Publication 2. This system uses a suite of three computer codes: PABLM, DACRIN, and KRONIC. In the new system, 50-year committed doses are calculated in accordance with the recommendations of the ICRP Publications 26 and 30, which were adopted by the US Department of Energy (DOE) in 1985. This new system calculates dose equivalent (DE) to individual organs and effective dose equivalent (EDE). The EDE is a risk-weighted DE that is designed to be an indicator of the potential health effects arising from the radiation dose. 16 refs., 1 fig., 38 tabs.

  14. [ESTIMATION OF IONIZING RADIATION EFFECTIVE DOSES IN THE INTERNATIONAL SPACE STATION CREWS BY THE METHOD OF CALCULATION MODELING].

    PubMed

    Mitrikas, V G

    2015-01-01

    Monitoring of the radiation loading on cosmonauts requires calculation of absorbed dose dynamics with regard to the stay of cosmonauts in specific compartments of the space vehicle that differ in shielding properties and lack means of radiation measurement. The paper discusses different aspects of calculation modeling of radiation effects on human body organs and tissues and reviews the effective dose estimates for cosmonauts working in one or another compartment over the previous period of the International space station operation. It was demonstrated that doses measured by a real or personal dosimeters can be used to calculate effective dose values. Correct estimation of accumulated effective dose can be ensured by consideration for time course of the space radiation quality factor.

  15. Aerosol based direct-write micro-additive fabrication method for sub-mm 3D metal-dielectric structures

    NASA Astrophysics Data System (ADS)

    Rahman, Taibur; Renaud, Luke; Heo, Deuk; Renn, Michael; Panat, Rahul

    2015-10-01

    The fabrication of 3D metal-dielectric structures at sub-mm length scale is highly important in order to realize low-loss passives and GHz wavelength antennas with applications in wearable and Internet-of-Things (IoT) devices. The inherent 2D nature of lithographic processes severely limits the available manufacturing routes to fabricate 3D structures. Further, the lithographic processes are subtractive and require the use of environmentally harmful chemicals. In this letter, we demonstrate an additive manufacturing method to fabricate 3D metal-dielectric structures at sub-mm length scale. A UV curable dielectric is dispensed from an Aerosol Jet system at 10-100 µm length scale and instantaneously cured to build complex 3D shapes at a length scale  <1 mm. A metal nanoparticle ink is then dispensed over the 3D dielectric using a combination of jetting action and tilted dispense head, also using the Aerosol Jet technique and at a length scale 10-100 µm, followed by the nanoparticle sintering. Simulation studies are carried out to demonstrate the feasibility of using such structures as mm-wave antennas. The manufacturing method described in this letter opens up the possibility of fabricating an entirely new class of custom-shaped 3D structures at a sub-mm length scale with potential applications in 3D antennas and passives.

  16. Development and Validation of HPLC Method for the Simultaneous Determination of Five Food Additives and Caffeine in Soft Drinks.

    PubMed

    Aşçı, Bürge; Dinç Zor, Şule; Aksu Dönmez, Özlem

    2016-01-01

    Box-Behnken design was applied to optimize high performance liquid chromatography (HPLC) conditions for the simultaneous determination of potassium sorbate, sodium benzoate, carmoisine, allura red, ponceau 4R, and caffeine in commercial soft drinks. The experimental variables chosen were pH (6.0-7.0), flow rate (1.0-1.4 mL/min), and mobile phase ratio (85-95% acetate buffer). Resolution values of all peak pairs were used as a response. Stationary phase was Inertsil OctaDecylSilane- (ODS-) 3V reverse phase column (250 × 4.6 mm, 5 μm) dimensions. The detection was performed at 230 nm. Optimal values were found 6.0 pH, 1.0 mL/min flow rate, and 95% mobile phase ratio for the method which was validated by calculating the linearity (r (2) > 0.9962), accuracy (recoveries ≥ 95.75%), precision (intraday variation ≤ 1.923%, interday variation ≤ 1.950%), limits of detection (LODs), and limits of quantification (LOQs) parameters. LODs and LOQs for analytes were in the range of 0.10-0.19 μg/mL and 0.33-0.63 μg/mL, respectively. The proposed method was applied successfully for the simultaneous determination of the mixtures of five food additives and caffeine in soft drinks.

  17. Development and Validation of HPLC Method for the Simultaneous Determination of Five Food Additives and Caffeine in Soft Drinks

    PubMed Central

    Aşçı, Bürge; Dinç Zor, Şule; Aksu Dönmez, Özlem

    2016-01-01

    Box-Behnken design was applied to optimize high performance liquid chromatography (HPLC) conditions for the simultaneous determination of potassium sorbate, sodium benzoate, carmoisine, allura red, ponceau 4R, and caffeine in commercial soft drinks. The experimental variables chosen were pH (6.0–7.0), flow rate (1.0–1.4 mL/min), and mobile phase ratio (85–95% acetate buffer). Resolution values of all peak pairs were used as a response. Stationary phase was Inertsil OctaDecylSilane- (ODS-) 3V reverse phase column (250 × 4.6 mm, 5 μm) dimensions. The detection was performed at 230 nm. Optimal values were found 6.0 pH, 1.0 mL/min flow rate, and 95% mobile phase ratio for the method which was validated by calculating the linearity (r2 > 0.9962), accuracy (recoveries ≥ 95.75%), precision (intraday variation ≤ 1.923%, interday variation ≤ 1.950%), limits of detection (LODs), and limits of quantification (LOQs) parameters. LODs and LOQs for analytes were in the range of 0.10–0.19 μg/mL and 0.33–0.63 μg/mL, respectively. The proposed method was applied successfully for the simultaneous determination of the mixtures of five food additives and caffeine in soft drinks. PMID:26989415

  18. LV wall segmentation using the variational level set method (LSM) with additional shape constraint for oedema quantification

    NASA Astrophysics Data System (ADS)

    Kadir, K.; Gao, H.; Payne, A.; Soraghan, J.; Berry, C.

    2012-10-01

    In this paper an automatic algorithm for the left ventricle (LV) wall segmentation and oedema quantification from T2-weighted cardiac magnetic resonance (CMR) images is presented. The extent of myocardial oedema delineates the ischaemic area-at-risk (AAR) after myocardial infarction (MI). Since AAR can be used to estimate the amount of salvageable myocardial post-MI, oedema imaging has potential clinical utility in the management of acute MI patients. This paper presents a new scheme based on the variational level set method (LSM) with additional shape constraint for the segmentation of T2-weighted CMR image. In our approach, shape information of the myocardial wall is utilized to introduce a shape feature of the myocardial wall into the variational level set formulation. The performance of the method is tested using real CMR images (12 patients) and the results of the automatic system are compared to manual segmentation. The mean perpendicular distances between the automatic and manual LV wall boundaries are in the range of 1-2 mm. Bland-Altman analysis on LV wall area indicates there is no consistent bias as a function of LV wall area, with a mean bias of -121 mm2 between individual investigator one (IV1) and LSM, and -122 mm2 between individual investigator two (IV2) and LSM when compared to two investigators. Furthermore, the oedema quantification demonstrates good correlation when compared to an expert with an average error of 9.3% for 69 slices of short axis CMR image from 12 patients.

  19. 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

  20. Comparison of Accuracy in Calculation of Absorbed Dose to Patients Following Bone Scan with 99mTc-Marked Diphosphonates by Two Different Background Correction Methods

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Damoori, Mehri; Tavakoli, Mohammad Bagher; Moslehi, Masoud

    2016-01-01

    To improve the accuracy of the activity quantification and the image quality in scintigraphy, scatter correction is a vital procedure. The aim of this study is to compare the accuracy in calculation of absorbed dose to patients following bone scan with 99mTc-marked diphosphonates (99mTc-MDP) by two different methods of background correction in conjugate view method. This study involved 22 patients referring to the Nuclear Medicine Center of Shahid Chamran Hospital, Isfahan, Iran. After the injection of 99mTc-MDP, whole-body images from patients were acquired at 10, 60, 90, and 180 min. Organ activities were calculated using the conjugate view method by Buijs and conventional background correction. Finally, the absorbed dose was calculated using the Medical Internal Radiation Dosimetry (MIRD) technique. The results of this study showed that the absorbed dose per unit of injected activity (rad/mCi) ± standard deviation for pelvis bone, bladder, and kidneys by Buijs method was 0.19 ± 0.05, 0.08 ± 0.01, and 0.03 ± 0.01 and by conventional method was 0.13 ± 0.04, 0.08 ± 0.01, and 0.024 ± 0.01, respectively. This showed that Buijs background correction method had a high accuracy compared to conventional method for the estimated absorbed dose of bone and kidneys whereas, for the bladder, its accuracy was low. PMID:27014610

  1. An investigation of the iterative reconstruction method iDose4 on a Philips CT Brilliance 64 using a Catphan 600 phantom

    NASA Astrophysics Data System (ADS)

    Olsson, Marie-Louise; Norrgren, Kristina

    2012-03-01

    The number of CT examinations giving a relatively high patient exposure is increasing. It is therefore important to optimize the imaging conditions at these investigations. Many steps have been taken to reduce the radiation doses in CT examinations. Currently much work is related to iterative image reconstruction methods as alternative to the filtered back projection method. The aim of this work was to evaluate quality parameters in images from a CT (Philips Brilliance 64) equipped with the iterative reconstruction method iDose4 using a Catphan 600 phantom with and without body simulating ring. CT scans using abdomen protocol were taken with various tube currents and tube voltage and keeping collimation and pitch unchanged for all scans. All collected data were reconstructed with different levels of iDose4 (Level 2, 4, 6) and traditional filtered back projection. Image quality parameters were evaluated using AutoQA Lite TM (Version 2.3 2007 Iris QA, LLC). Results from the study shows that the iterative reconstruction method decreases the noise with 15-45% compared with filtered back projection depending on which level of iDose4 is used. The percentage reduction in noise level is the same with and without body simulating ring. Low contrast was improved with iDose4 and spatial resolution is only marginally affected by the method of reconstruction. However by reducing the image noise, the detectability can be improved. Our conclusion is that there is great potential to reduce the noise and thereby improve the image quality by using iterative reconstruction methods. This can also be used to lower radiation dose and maintain image quality or improve image quality.

  2. Interoceptive conditioning with the nicotine stimulus: extinction learning as a method for assessing stimulus similarity across doses.

    PubMed

    Polewan, Robert J; Savala, Stephanie A; Bevins, Rick A

    2013-02-01

    Interoceptive conditioning involving the nicotine stimulus likely contributes to chronic tobacco use. To better understand the nature of this interoceptive conditioning, we compared generalization during repeated extinction with generalization in a 'transfer of extinction' test using a wide range of test doses. Rats were first trained in the discriminated goal-tracking task in which nicotine (0.2 or 0.4 mg/kg), but not saline, was paired with repeated intermittent access to sucrose. Across sessions, nicotine acquired control of approach behavior directed at the location of previous sucrose deliveries. Extinction followed with eight 20-min sessions without sucrose access; extinction doses of nicotine ranged from 0.05 to 0.6 mg/kg. In rats trained with 0.4 mg/kg, the 0.1, 0.2, and 0.6 mg/kg doses evoked comparable responding across extinction sessions; substitution was only partial at 0.05 and 0.075 mg/kg (i.e. above saline controls, but less than the training dose). With the 0.2 mg/kg training dose, complete generalization was seen only at the 0.1 and 0.4 mg/kg doses. After extinction, rats were given a transfer test with their training dose. Rats trained with 0.4 mg/kg showed full transfer of extinction learning with 0.1, 0.2, and 0.6 mg/kg (i.e. responding comparable with extinction with the training dose). Partial transfer was observed at 0.075 mg/kg. With the 0.2 mg/kg nicotine dose, only 0.4 mg/kg fully generalized; 0.075, 0.1, and 0.6 mg/kg showed partial transfer. Extinction with 0.05 mg/kg dose did not show transfer to either training dose. These findings indicated that conclusions regarding stimulus similarity across nicotine doses can vary with testing protocol.

  3. Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2008-05-20

    A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

  4. Radiation doses of employees of a Nuclear Medicine Department after implementation of more rigorous radiation protection methods.

    PubMed

    Piwowarska-Bilska, Hanna; Supinska, Aleksandra; Listewnik, Maria H; Zorga, Piotr; Birkenfeld, Bozena

    2013-11-01

    The appropriate radiation protection measures applied in departments of nuclear medicine should lead to a reduction in doses received by the employees. During 1991-2007, at the Department of Nuclear Medicine of Pomeranian Medical University (Szczecin, Poland), nurses received on average two-times higher (4.6 mSv) annual doses to the whole body than those received by radiopharmacy technicians. The purpose of this work was to examine whether implementation of changes in the radiation protection protocol will considerably influence the reduction in whole-body doses received by the staff that are the most exposed. A reduction in nurses' exposure by ~63 % took place in 2008-11, whereas the exposure of radiopharmacy technicians grew by no more than 22 % in comparison with that in the period 1991-2007. Proper reorganisation of the work in departments of nuclear medicine can considerably affect dose reduction and bring about equal distribution of the exposure.

  5. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized by polyol method

    NASA Astrophysics Data System (ADS)

    Junaidi, Triyana, Kuwa