Dosimetric investigation of LDR brachytherapy ¹⁹²Ir wires by Monte Carlo and TPS calculations.

PubMed

Bozkurt, Ahmet; Acun, Hediye; Kemikler, Gonul

2013-01-01

The aim of this study was to investigate the dose rate distribution around (192)Ir wires used as radioactive sources in low-dose-rate brachytherapy applications. Monte Carlo modeling of a 0.3-mm diameter source and its surrounding water medium was performed for five different wire lengths (1-5 cm) using the MCNP software package. The computed dose rates per unit of air kerma at distances from 0.1 up to 10 cm away from the source were first verified with literature data sets. Then, the simulation results were compared with the calculations from the XiO CMS commercial treatment planning system. The study results were found to be in concordance with the treatment planning system calculations except for the shorter wires at close distances.

MutAIT: an online genetic toxicology data portal and analysis tools.

PubMed

Avancini, Daniele; Menzies, Georgina E; Morgan, Claire; Wills, John; Johnson, George E; White, Paul A; Lewis, Paul D

2016-05-01

Assessment of genetic toxicity and/or carcinogenic activity is an essential element of chemical screening programs employed to protect human health. Dose-response and gene mutation data are frequently analysed by industry, academia and governmental agencies for regulatory evaluations and decision making. Over the years, a number of efforts at different institutions have led to the creation and curation of databases to house genetic toxicology data, largely, with the aim of providing public access to facilitate research and regulatory assessments. This article provides a brief introduction to a new genetic toxicology portal called Mutation Analysis Informatics Tools (MutAIT) (www.mutait.org) that provides easy access to two of the largest genetic toxicology databases, the Mammalian Gene Mutation Database (MGMD) and TransgenicDB. TransgenicDB is a comprehensive collection of transgenic rodent mutation data initially compiled and collated by Health Canada. The updated MGMD contains approximately 50 000 individual mutation spectral records from the published literature. The portal not only gives access to an enormous quantity of genetic toxicology data, but also provides statistical tools for dose-response analysis and calculation of benchmark dose. Two important R packages for dose-response analysis are provided as web-distributed applications with user-friendly graphical interfaces. The 'drsmooth' package performs dose-response shape analysis and determines various points of departure (PoD) metrics and the 'PROAST' package provides algorithms for dose-response modelling. The MutAIT statistical tools, which are currently being enhanced, provide users with an efficient and comprehensive platform to conduct quantitative dose-response analyses and determine PoD values that can then be used to calculate human exposure limits or margins of exposure. © The Author 2015. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Conformity of commercial oral single solid unit dose packages in hospital pharmacy practice.

PubMed

Thibault, Maxime; Prot-Labarthe, Sonia; Bussières, Jean-François; Lebel, Denis

2008-06-01

There are limited published data on the labelling of single unit dose packages in hospitals. The study was conducted in three large hospitals (two adult and one paediatric) in the metropolitan Montreal area, Quebec, Canada. The objective is to evaluate the labelling of commercial oral single solid unit dose packages available in Canadian urban hospital pharmacy practice. The study endpoint was the labelling conformity of each unit dose package for each criterion and overall for each manufacturer. Complete labelling of unit dose packages should include the following information: (1) brand name, (2) international non-proprietary name or generic name, (3) dosage, (4) pharmaceutical form, (5) manufacturer's name, (6) expiry date, (7) batch number and (8) drug identification number. We also evaluated the ease with which a single unit dose package is detached from a multiple unit dose package for quick, easy and safe use by pharmacy staff. Conformity levels were compared between brand-name and generic packages. A total of 124 different unit dose packages were evaluated. The level of conformity of each criterion varied between 19 and 50%. Only 43% of unit dose packages provided an easy-to-detach system for single doses. Among the 14 manufacturers with three or more unit dose packages evaluated, eight (57%) had a conformity level less than 50%. This study describes the conformity of commercial oral single solid unit dose packages in hospital pharmacy practice in Quebec. A large proportion of unit dose packages do not conform to a set of nine criteria set out in the guidelines of the American Society of Health-System Pharmacists and the Canadian Society of Hospital Pharmacists.

The comet moment as a measure of DNA damage in the comet assay.

PubMed

Kent, C R; Eady, J J; Ross, G M; Steel, G G

1995-06-01

The development of rapid assays of radiation-induced DNA damage requires the definition of reliable parameters for the evaluation of dose-response relationships to compare with cellular endpoints. We have used the single-cell gel electrophoresis (SCGE) or 'comet' assay to measure DNA damage in individual cells after irradiation. Both the alkaline and neutral protocols were used. In both cases, DNA was stained with ethidium bromide and viewed using a fluorescence microscope at 516-560 nm. Images of comets were stored as 512 x 512 pixel images using OPTIMAS, an image analysis software package. Using this software we tested various parameters for measuring DNA damage. We have developed a method of analysis that rigorously conforms to the mathematical definition of the moment of inertia of a plane figure. This parameter does not require the identification of separate head and tail regions, but rather calculates a moment of the whole comet image. We have termed this parameter 'comet moment'. This method is simple to calculate and can be performed using most image analysis software packages that support macro facilities. In experiments on CHO-K1 cells, tail length was found to increase linearly with dose, but plateaued at higher doses. Comet moment also increased linearly with dose, but over a larger dose range than tail length and had no tendency to plateau.

Comprehensive evaluations of cone-beam CT dose in image-guided radiation therapy via GPU-based Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Montanari, Davide; Scolari, Enrica; Silvestri, Chiara; Jiang Graves, Yan; Yan, Hao; Cervino, Laura; Rice, Roger; Jiang, Steve B.; Jia, Xun

2014-03-01

Cone beam CT (CBCT) has been widely used for patient setup in image-guided radiation therapy (IGRT). Radiation dose from CBCT scans has become a clinical concern. The purposes of this study are (1) to commission a graphics processing unit (GPU)-based Monte Carlo (MC) dose calculation package gCTD for Varian On-Board Imaging (OBI) system and test the calculation accuracy, and (2) to quantitatively evaluate CBCT dose from the OBI system in typical IGRT scan protocols. We first conducted dose measurements in a water phantom. X-ray source model parameters used in gCTD are obtained through a commissioning process. gCTD accuracy is demonstrated by comparing calculations with measurements in water and in CTDI phantoms. Twenty-five brain cancer patients are used to study dose in a standard-dose head protocol, and 25 prostate cancer patients are used to study dose in pelvis protocol and pelvis spotlight protocol. Mean dose to each organ is calculated. Mean dose to 2% voxels that have the highest dose is also computed to quantify the maximum dose. It is found that the mean dose value to an organ varies largely among patients. Moreover, dose distribution is highly non-homogeneous inside an organ. The maximum dose is found to be 1-3 times higher than the mean dose depending on the organ, and is up to eight times higher for the entire body due to the very high dose region in bony structures. High computational efficiency has also been observed in our studies, such that MC dose calculation time is less than 5 min for a typical case.

Definition of Small Gram Quantity Contents for Type B Radioactive Material Transportation Packages: Activity-Based Content Limitations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitaraman, S; Kim, S; Biswas, D

2010-10-27

Since the 1960's, the Department of Transportation Specification (DOT Spec) 6M packages have been used extensively for transportation of Type B quantities of radioactive materials between Department of Energy (DOE) facilities, laboratories, and productions sites. However, due to the advancement of packaging technology, the aging of the 6M packages, and variability in the quality of the packages, the DOT implemented a phased elimination of the 6M specification packages (and other DOT Spec packages) in favor of packages certified to meet federal performance requirements. DOT issued the final rule in the Federal Register on October 1, 2004 requiring that use ofmore » the DOT Specification 6M be discontinued as of October 1, 2008. A main driver for the change was the fact that the 6M specification packagings were not supported by a Safety Analysis Report for Packaging (SARP) that was compliant with Title 10 of the Code of Federal Regulations part 71 (10 CFR 71). Therefore, materials that would have historically been shipped in 6M packages are being identified as contents in Type B (and sometimes Type A fissile) package applications and addenda that are to be certified under the requirements of 10 CFR 71. The requirements in 10 CFR 71 include that the Safety Analysis Report for Packaging (SARP) must identify the maximum radioactivity of radioactive constituents and maximum quantities of fissile constituents (10 CFR 71.33(b)(1) and 10 CFR 71.33(b)(2)), and that the application (i.e., SARP submittal or SARP addendum) demonstrates that the external dose rate (due to the maximum radioactivity of radioactive constituents and maximum quantities of fissile constituents) on the surface of the packaging (i.e., package and contents) not exceed 200 mrem/hr (10 CFR 71.35(a), 10 CFR 71.47(a)). It has been proposed that a 'Small Gram Quantity' of radioactive material be defined, such that, when loaded in a transportation package, the dose rates at external points of an unshielded packaging not exceed the regulatory limits prescribed by 10 CFR 71 for non-exclusive shipments. The mass of each radioisotope presented in this paper is limited by the radiation dose rate on the external surface of the package, which per the regulatory limit should not exceed 200 mrem/hr. The results presented are a compendium of allowable masses of a variety of different isotopes (with varying impurity levels of beryllium in some of the actinide isotopes) that, when loaded in an unshielded packaging, do not result in an external dose rate on the surface of the package that exceeds 190 mrem/hr (190 mrem/hr was chosen to provide 5% conservatism relative to the regulatory limit). These mass limits define the term 'Small Gram Quantity' (SGQ) contents in the context of radioactive material transportation packages. The term SGQ is isotope-specific and pertains to contents in radioactive material transportation packages that do not require shielding and still satisfy the external dose rate requirements. Since these calculated mass limits are for contents without shielding, they are conservative for packaging materials that provide some limited shielding or if the contents are placed into a shielded package. The isotopes presented in this paper were chosen as the isotopes that Department of Energy (DOE) sites most likely need to ship. Other more rarely shipped isotopes, along with industrial and medical isotopes, are planned to be included in subsequent extensions of this work.« less

Use of computer code for dose distribution studies in A 60CO industrial irradiator

NASA Astrophysics Data System (ADS)

Piña-Villalpando, G.; Sloan, D. P.

1995-09-01

This paper presents a benchmark comparison between calculated and experimental absorbed dose values tor a typical product, in a 60Co industrial irradiator, located at ININ, México. The irradiator is a two levels, two layers system with overlapping product configuration with activity around 300kCi. Experimental values were obtanied from routine dosimetry, using red acrylic pellets. Typical product was Petri dishes packages, apparent density 0.13 g/cm3; that product was chosen because uniform size, large quantity and low density. Minimum dose was fixed in 15 kGy. Calculated values were obtained from QAD-CGGP code. This code uses a point kernel technique, build-up factors fitting was done by geometrical progression and combinatorial geometry is used for system description. Main modifications for the code were related with source sumilation, using punctual sources instead of pencils and an energy and anisotropic emission spectrums were included. Results were, for maximum dose, calculated value (18.2 kGy) was 8% higher than experimental average value (16.8 kGy); for minimum dose, calculated value (13.8 kGy) was 3% higher than experimental average value (14.3 kGy).

BWR ASSEMBLY SOURCE TERMS FOR WASTE PACKAGE DESIGN

DOE Office of Scientific and Technical Information (OSTI.GOV)

T.L. Lotz

1997-02-15

This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development Department (WPDD) to provide boiling water reactor (BWR) assembly radiation source term data for use during Waste Package (WP) design. The BWR assembly radiation source terms are to be used for evaluation of radiolysis effects at the WP surface, and for personnel shielding requirements during assembly or WP handling operations. The objectives of this evaluation are to generate BWR assembly radiation source terms that bound selected groupings of BWR assemblies, with regard to assembly average burnup and cooling time, which comprise the anticipated MGDS BWR commercialmore » spent nuclear fuel (SNF) waste stream. The source term data is to be provided in a form which can easily be utilized in subsequent shielding/radiation dose calculations. Since these calculations may also be used for Total System Performance Assessment (TSPA), with appropriate justification provided by TSPA, or radionuclide release rate analysis, the grams of each element and additional cooling times out to 25 years will also be calculated and the data included in the output files.« less

Effect on moisture permeability of typewriting on unit dose package surfaces.

PubMed

Rackson, J T; Zellhofer, M J; Birmingham, P H

1984-10-01

The effects of typewriting on labels of two unit dose packages with respect to moisture permeability were examined. Using an electric typewriter, a standard label format was imprinted on two different types of class A unit dose packages: (1) a heat-sealed paper-backed foil and cellofilm strip pouch, and (2) a copolyester and polyethylene multiple-cup blister with a heat-sealed paper-backed foil and cellofilm cover. The labels were typed at various typing-element impact settings. The official USP test for water permeation was then performed on typed packages and untyped control packages. The original untyped packages were confirmed to be USP class A quality. The packages for which successively harder impact settings were used showed a corresponding increase in moisture permeability. This resulted in a lowering of USP package ratings from class A to class B and D, some of which would be unsuitable for use in any unit dose system under current FDA repackaging standards. Typing directly onto the label of a unit dose package before it is sealed will most likely damage the package and possibly make it unfit for use. Pharmacists who must type labels for the unit dose packages studied should use the lowest possible typewriter impact setting and test for damage using the USP moisture-permeation test.

SU-E-T-169: Evaluation of Oncentra TPS for Nasopharynx Brachy Using Patient Specific Voxel Phantom and EGSnrc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadad, K; Zoherhvand, M; Faghihi, R

2014-06-01

Purpose: Nasopharnx carcinoma (NPC) treatment is being carried out using Ir-192 HDR seeds in Mehdieh Hospital in Hamadan, Iran. The Oncentra™ TPS is based on optimized TG-43 formalism which disregards heterogeneity in the treatment area. Due to abundant heterogeneity in head and neck, comparison of the Oncentra™ TPS dose evaluation and an accurate dose calculation method in NPC brachytherapy is the objective of this study. Methods: CT DICOMs of a patient with NPC obtained from Mehdieh Hospital used to create 3D voxel phantom with CTCREATE utility of EGSnrc code package. The voxel phantom together with Ir-192 HDR brachytherapy source weremore » the input to DOSXYZnrc to calculate the 3D dose distribution. The sources were incorporate with type 6 source in DOSXYZnrc and their dwell times were taken into account in final dose calculations. Results: The direct comparison between isodoses as well as DVHs for the GTV, PTV and CTV obtained by Oncentra™ and EGSnrc Monte Carlo code are made. EGSnrc results are obtained using 5×10{sup 9} histories to reduce the statistical error below 1% in GTV and 5% in 5% dose areas. The standard ICRP700 cross section library is employed in DOSXYZnrc dose calculation. Conclusion: A direct relationship between increased dose differences and increased material density (hence heterogeneity) is observed when isodoses contours of the TPS and DOSXYZnrc are compared. Regarding the point dose calculations, the differences range from 1.2% in PTV to 5.6% for cavity region and 7.8% for bone regions. While Oncentra™ TPS overestimates the dose in cavities, it tends to underestimate dose depositions within bones.« less

Dose conversion coefficients for neutron exposure to the lens of the human eye.

PubMed

Manger, R P; Bellamy, M B; Eckerman, K F

2012-03-01

Dose conversion coefficients for the lens of the human eye have been calculated for neutron exposure at energies from 1 × 10(-9) to 20 MeV and several standard orientations: anterior-to-posterior, rotational and right lateral. MCNPX version 2.6.0, a Monte Carlo-based particle transport package, was used to determine the energy deposited in the lens of the eye. The human eyeball model was updated by partitioning the lens into sensitive and insensitive volumes as the anterior portion (sensitive volume) of the lens being more radiosensitive and prone to cataract formation. The updated eye model was used with the adult UF-ORNL mathematical phantom in the MCNPX transport calculations.

A comparison of medication administration errors from original medication packaging and multi-compartment compliance aids in care homes: A prospective observational study.

PubMed

Gilmartin-Thomas, Julia Fiona-Maree; Smith, Felicity; Wolfe, Rory; Jani, Yogini

2017-07-01

No published study has been specifically designed to compare medication administration errors between original medication packaging and multi-compartment compliance aids in care homes, using direct observation. Compare the effect of original medication packaging and multi-compartment compliance aids on medication administration accuracy. Prospective observational. Ten Greater London care homes. Nurses and carers administering medications. Between October 2014 and June 2015, a pharmacist researcher directly observed solid, orally administered medications in tablet or capsule form at ten purposively sampled care homes (five only used original medication packaging and five used both multi-compartment compliance aids and original medication packaging). The medication administration error rate was calculated as the number of observed doses administered (or omitted) in error according to medication administration records, compared to the opportunities for error (total number of observed doses plus omitted doses). Over 108.4h, 41 different staff (35 nurses, 6 carers) were observed to administer medications to 823 residents during 90 medication administration rounds. A total of 2452 medication doses were observed (1385 from original medication packaging, 1067 from multi-compartment compliance aids). One hundred and seventy eight medication administration errors were identified from 2493 opportunities for error (7.1% overall medication administration error rate). A greater medication administration error rate was seen for original medication packaging than multi-compartment compliance aids (9.3% and 3.1% respectively, risk ratio (RR)=3.9, 95% confidence interval (CI) 2.4 to 6.1, p<0.001). Similar differences existed when comparing medication administration error rates between original medication packaging (from original medication packaging-only care homes) and multi-compartment compliance aids (RR=2.3, 95%CI 1.1 to 4.9, p=0.03), and between original medication packaging and multi-compartment compliance aids within care homes that used a combination of both medication administration systems (RR=4.3, 95%CI 2.7 to 6.8, p<0.001). A significant difference in error rate was not observed between use of a single or combination medication administration system (p=0.44). The significant difference in, and high overall, medication administration error rate between original medication packaging and multi-compartment compliance aids supports the use of the latter in care homes, as well as local investigation of tablet and capsule impact on medication administration errors and staff training to prevent errors occurring. As a significant difference in error rate was not observed between use of a single or combination medication administration system, common practice of using both multi-compartment compliance aids (for most medications) and original packaging (for medications with stability issues) is supported. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulations of neutron transport at low energy: a comparison between GEANT and MCNP.

PubMed

Colonna, N; Altieri, S

2002-06-01

The use of the simulation tool GEANT for neutron transport at energies below 20 MeV is discussed, in particular with regard to shielding and dose calculations. The reliability of the GEANT/MICAP package for neutron transport in a wide energy range has been verified by comparing the results of simulations performed with this package in a wide energy range with the prediction of MCNP-4B, a code commonly used for neutron transport at low energy. A reasonable agreement between the results of the two codes is found for the neutron flux through a slab of material (iron and ordinary concrete), as well as for the dose released in soft tissue by neutrons. These results justify the use of the GEANT/MICAP code for neutron transport in a wide range of applications, including health physics problems.

Calculation of organ doses in x-ray examinations of premature babies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smans, Kristien; Tapiovaara, Markku; Cannie, Mieke

Lung disease represents one of the most life-threatening conditions in prematurely born children. In the evaluation of the neonatal chest, the primary and most important diagnostic study is the chest radiograph. Since prematurely born children are very sensitive to radiation, those radiographs may lead to a significant radiation detriment. Knowledge of the radiation dose is therefore necessary to justify the exposures. To calculate doses in the entire body and in specific organs, computational models of the human anatomy are needed. Using medical imaging techniques, voxel phantoms have been developed to achieve a representation as close as possible to the anatomicalmore » properties. In this study two voxel phantoms, representing prematurely born babies, were created from computed tomography- and magnetic resonance images: Phantom 1 (1910 g) and Phantom 2 (590 g). The two voxel phantoms were used in Monte Carlo calculations (MCNPX) to assess organ doses. The results were compared with the commercially available software package PCXMC in which the available mathematical phantoms can be downsized toward the prematurely born baby. The simple phantom-scaling method used in PCXMC seems to be sufficient to calculate doses for organs within the radiation field. However, one should be careful in specifying the irradiation geometry. Doses in organs that are wholly or partially outside the primary radiation field depend critically on the irradiation conditions and the phantom model.« less

Modeling parameterized geometry in GPU-based Monte Carlo particle transport simulation for radiotherapy.

PubMed

Chi, Yujie; Tian, Zhen; Jia, Xun

2016-08-07

Monte Carlo (MC) particle transport simulation on a graphics-processing unit (GPU) platform has been extensively studied recently due to the efficiency advantage achieved via massive parallelization. Almost all of the existing GPU-based MC packages were developed for voxelized geometry. This limited application scope of these packages. The purpose of this paper is to develop a module to model parametric geometry and integrate it in GPU-based MC simulations. In our module, each continuous region was defined by its bounding surfaces that were parameterized by quadratic functions. Particle navigation functions in this geometry were developed. The module was incorporated to two previously developed GPU-based MC packages and was tested in two example problems: (1) low energy photon transport simulation in a brachytherapy case with a shielded cylinder applicator and (2) MeV coupled photon/electron transport simulation in a phantom containing several inserts of different shapes. In both cases, the calculated dose distributions agreed well with those calculated in the corresponding voxelized geometry. The averaged dose differences were 1.03% and 0.29%, respectively. We also used the developed package to perform simulations of a Varian VS 2000 brachytherapy source and generated a phase-space file. The computation time under the parameterized geometry depended on the memory location storing the geometry data. When the data was stored in GPU's shared memory, the highest computational speed was achieved. Incorporation of parameterized geometry yielded a computation time that was ~3 times of that in the corresponding voxelized geometry. We also developed a strategy to use an auxiliary index array to reduce frequency of geometry calculations and hence improve efficiency. With this strategy, the computational time ranged in 1.75-2.03 times of the voxelized geometry for coupled photon/electron transport depending on the voxel dimension of the auxiliary index array, and in 0.69-1.23 times for photon only transport.

NOTE: MMCTP: a radiotherapy research environment for Monte Carlo and patient-specific treatment planning

NASA Astrophysics Data System (ADS)

Alexander, A.; DeBlois, F.; Stroian, G.; Al-Yahya, K.; Heath, E.; Seuntjens, J.

2007-07-01

Radiotherapy research lacks a flexible computational research environment for Monte Carlo (MC) and patient-specific treatment planning. The purpose of this study was to develop a flexible software package on low-cost hardware with the aim of integrating new patient-specific treatment planning with MC dose calculations suitable for large-scale prospective and retrospective treatment planning studies. We designed the software package 'McGill Monte Carlo treatment planning' (MMCTP) for the research development of MC and patient-specific treatment planning. The MMCTP design consists of a graphical user interface (GUI), which runs on a simple workstation connected through standard secure-shell protocol to a cluster for lengthy MC calculations. Treatment planning information (e.g., images, structures, beam geometry properties and dose distributions) is converted into a convenient MMCTP local file storage format designated, the McGill RT format. MMCTP features include (a) DICOM_RT, RTOG and CADPlan CART format imports; (b) 2D and 3D visualization views for images, structure contours, and dose distributions; (c) contouring tools; (d) DVH analysis, and dose matrix comparison tools; (e) external beam editing; (f) MC transport calculation from beam source to patient geometry for photon and electron beams. The MC input files, which are prepared from the beam geometry properties and patient information (e.g., images and structure contours), are uploaded and run on a cluster using shell commands controlled from the MMCTP GUI. The visualization, dose matrix operation and DVH tools offer extensive options for plan analysis and comparison between MC plans and plans imported from commercial treatment planning systems. The MMCTP GUI provides a flexible research platform for the development of patient-specific MC treatment planning for photon and electron external beam radiation therapy. The impact of this tool lies in the fact that it allows for systematic, platform-independent, large-scale MC treatment planning for different treatment sites. Patient recalculations were performed to validate the software and ensure proper functionality.

Dose conversion coefficients for neutron exposure to the lens of the human eye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manger, Ryan P; Bellamy, Michael B; Eckerman, Keith F

Dose conversion coefficients for the lens of the human eye have been calculated for neutron exposure at energies from 1 x 10{sup -9} to 20 MeV and several standard orientations: anterior-to-posterior, rotational and right lateral. MCNPX version 2.6.0, a Monte Carlo-based particle transport package, was used to determine the energy deposited in the lens of the eye. The human eyeball model was updated by partitioning the lens into sensitive and insensitive volumes as the anterior portion (sensitive volume) of the lens being more radiosensitive and prone to cataract formation. The updated eye model was used with the adult UF-ORNL mathematicalmore » phantom in the MCNPX transport calculations.« less

Evaluation of an alternative shielding materials for F-127 transport package

NASA Astrophysics Data System (ADS)

Gual, Maritza R.; Mesquita, Amir Z.; Pereira, Cláubia

2018-03-01

Lead is used as radiation shielding material for the Nordion's F-127 source shipping container is used for transport and storage of the GammaBeam -127's cobalt-60 source of the Nuclear Technology Development Center (CDTN) located in Belo Horizonte, Brazil. As an alternative, Th, Tl and WC have been evaluated as radiation shielding material. The goal is to check their behavior regarding shielding and dosing. Monte Carlo MCNPX code is used for the simulations. In the MCNPX calculation was used one cylinder as exclusion surface instead one sphere. Validation of MCNPX gamma doses calculations was carried out through comparison with experimental measurements. The results show that tungsten carbide WC is better shielding material for γ-ray than lead shielding.

Effect of low-dose gamma irradiation on Staphylococcus aureus and product packaging in ready-to-eat ham and cheese sandwiches.

PubMed

Lamb, Jennifer L; Gogley, Jennifer M; Thompson, M Jasmine; Solis, Daniel R; Sen, Sumit

2002-11-01

Staphylococcus aureus is a common pathogen that causes foodborne illness. Traditional methods for controlling S. aureus do not address postprocess contamination. Low-dose gamma irradiation is effective in reducing pathogens in a variety of foods and may be effective in reducing S. aureus in ready-to-eat foods. The effects of gamma irradiation on product packaging should also be considered. The objective of this study was to determine the effects of gamna irradiation on product packaging and on S. aureus in ready-to-eat ham and cheese sandwiches. The effects of refrigerated storage on irradiated and nonirradiated sandwiches were also investigated. Ham and cheese sandwiches were inoculated with 10(6) or 10(7) CFU of S. aureus per g, frozen, irradiated, and analyzed by a standard plate count method. D10-values, the amount of irradiation needed to elicit a 1-log10 reduction of bacteria, were calculated. In addition, irradiated sandwiches were analyzed after 1, 13, 27, and 39 days of storage at 4 degrees C. The integrity of postirradiated packaging material was analyzed using Fourier transform infrared (FTIR) spectroscopy. Two experiments yielded D10-values of 0.62 and 0.63. During refrigerated storage, sandwiches irradiated with 5.9 kGy showed no S. aureus growth at any time; sandwiches irradiated with 3.85 kGy showed a 6.18-log reduction in S. aureus after 13 days; and nonirradiated sandwiches showed a 0.53-log increase in S. aureus after 39 days. FTIR spectroscopy showed that the label side and the bulge side were composed of polyethylene terephthalate and nylon 6, respectively. No significant change in the packaging due to irradiation was detected. In this study, low-dose gamma irradiation was shown to be an effective method for reducing S. aureus in ready-to-eat ham and cheese sandwiches and proved to be more efficacious than refrigeration alone. Additionally, package integrity was not adversely affected by gamma irradiation.

Fast CPU-based Monte Carlo simulation for radiotherapy dose calculation.

PubMed

Ziegenhein, Peter; Pirner, Sven; Ph Kamerling, Cornelis; Oelfke, Uwe

2015-08-07

Monte-Carlo (MC) simulations are considered to be the most accurate method for calculating dose distributions in radiotherapy. Its clinical application, however, still is limited by the long runtimes conventional implementations of MC algorithms require to deliver sufficiently accurate results on high resolution imaging data. In order to overcome this obstacle we developed the software-package PhiMC, which is capable of computing precise dose distributions in a sub-minute time-frame by leveraging the potential of modern many- and multi-core CPU-based computers. PhiMC is based on the well verified dose planning method (DPM). We could demonstrate that PhiMC delivers dose distributions which are in excellent agreement to DPM. The multi-core implementation of PhiMC scales well between different computer architectures and achieves a speed-up of up to 37[Formula: see text] compared to the original DPM code executed on a modern system. Furthermore, we could show that our CPU-based implementation on a modern workstation is between 1.25[Formula: see text] and 1.95[Formula: see text] faster than a well-known GPU implementation of the same simulation method on a NVIDIA Tesla C2050. Since CPUs work on several hundreds of GB RAM the typical GPU memory limitation does not apply for our implementation and high resolution clinical plans can be calculated.

SU-F-T-193: Evaluation of a GPU-Based Fast Monte Carlo Code for Proton Therapy Biological Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taleei, R; Qin, N; Jiang, S

2016-06-15

Purpose: Biological treatment plan optimization is of great interest for proton therapy. It requires extensive Monte Carlo (MC) simulations to compute physical dose and biological quantities. Recently, a gPMC package was developed for rapid MC dose calculations on a GPU platform. This work investigated its suitability for proton therapy biological optimization in terms of accuracy and efficiency. Methods: We performed simulations of a proton pencil beam with energies of 75, 150 and 225 MeV in a homogeneous water phantom using gPMC and FLUKA. Physical dose and energy spectra for each ion type on the central beam axis were scored. Relativemore » Biological Effectiveness (RBE) was calculated using repair-misrepair-fixation model. Microdosimetry calculations were performed using Monte Carlo Damage Simulation (MCDS). Results: Ranges computed by the two codes agreed within 1 mm. Physical dose difference was less than 2.5 % at the Bragg peak. RBE-weighted dose agreed within 5 % at the Bragg peak. Differences in microdosimetric quantities such as dose average lineal energy transfer and specific energy were < 10%. The simulation time per source particle with FLUKA was 0.0018 sec, while gPMC was ∼ 600 times faster. Conclusion: Physical dose computed by FLUKA and gPMC were in a good agreement. The RBE differences along the central axis were small, and RBE-weighted dose difference was found to be acceptable. The combined accuracy and efficiency makes gPMC suitable for proton therapy biological optimization.« less

Confidence limit calculation for antidotal potency ratio derived from lethal dose 50

PubMed Central

Manage, Ananda; Petrikovics, Ilona

2013-01-01

AIM: To describe confidence interval calculation for antidotal potency ratios using bootstrap method. METHODS: We can easily adapt the nonparametric bootstrap method which was invented by Efron to construct confidence intervals in such situations like this. The bootstrap method is a resampling method in which the bootstrap samples are obtained by resampling from the original sample. RESULTS: The described confidence interval calculation using bootstrap method does not require the sampling distribution antidotal potency ratio. This can serve as a substantial help for toxicologists, who are directed to employ the Dixon up-and-down method with the application of lower number of animals to determine lethal dose 50 values for characterizing the investigated toxic molecules and eventually for characterizing the antidotal protections by the test antidotal systems. CONCLUSION: The described method can serve as a useful tool in various other applications. Simplicity of the method makes it easier to do the calculation using most of the programming software packages. PMID:25237618

Comparison of GATE/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV.

PubMed

Maigne, L; Perrot, Y; Schaart, D R; Donnarieix, D; Breton, V

2011-02-07

The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between 15 keV and 20 MeV by means of GATE 6.0, which makes use of the GEANT4 version 9.2 Standard Electromagnetic Physics Package. The results are compared to the well-validated codes EGSnrc and MCNP4C. It is shown that recent improvements made to the GEANT4/GATE software result in significantly better agreement with the other codes. We furthermore illustrate several issues of general interest to GATE and GEANT4 users who wish to perform accurate simulations involving electrons. Provided that the electron step size is sufficiently restricted, GATE 6.0 and EGSnrc dose point kernels are shown to agree to within less than 3% of the maximum dose between 50 keV and 4 MeV, while pencil beam kernels are found to agree to within less than 4% of the maximum dose between 15 keV and 20 MeV.

Water equivalency evaluation of PRESAGE® dosimeters for dosimetry of Cs-137 and Ir-192 brachytherapy sources

NASA Astrophysics Data System (ADS)

Gorjiara, Tina; Hill, Robin; Kuncic, Zdenka; Baldock, Clive

2010-11-01

A major challenge in brachytherapy dosimetry is the measurement of steep dose gradients. This can be achieved with a high spatial resolution three dimensional (3D) dosimeter. PRESAGE® is a polyurethane based dosimeter which is suitable for 3D dosimetry. Since an ideal dosimeter is radiologically water equivalent, we have investigated the relative dose response of three different PRESAGE® formulations, two with a lower chloride and bromide content than original one, for Cs-137 and Ir-192 brachytherapy sources. Doses were calculated using the EGSnrc Monte Carlo package. Our results indicate that PRESAGE® dosimeters are suitable for relative dose measurement of Cs-137 and Ir-192 brachytherapy sources and the lower halogen content PRESAGE® dosimeters are more water equivalent than the original formulation.

Dose calculations at high altitudes and in deep space with GEANT4 using BIC and JQMD models for nucleus nucleus reactions

NASA Astrophysics Data System (ADS)

Sihver, L.; Matthiä, D.; Koi, T.; Mancusi, D.

2008-10-01

Radiation exposure of aircrew is more and more recognized as an occupational hazard. The ionizing environment at standard commercial aircraft flight altitudes consists mainly of secondary particles, of which the neutrons give a major contribution to the dose equivalent. Accurate estimations of neutron spectra in the atmosphere are therefore essential for correct calculations of aircrew doses. Energetic solar particle events (SPE) could also lead to significantly increased dose rates, especially at routes close to the North Pole, e.g. for flights between Europe and USA. It is also well known that the radiation environment encountered by personnel aboard low Earth orbit (LEO) spacecraft or aboard a spacecraft traveling outside the Earth's protective magnetosphere is much harsher compared with that within the atmosphere since the personnel are exposed to radiation from both galactic cosmic rays (GCR) and SPE. The relative contribution to the dose from GCR when traveling outside the Earth's magnetosphere, e.g. to the Moon or Mars, is even greater, and reliable and accurate particle and heavy ion transport codes are essential to calculate the radiation risks for both aircrew and personnel on spacecraft. We have therefore performed calculations of neutron distributions in the atmosphere, total dose equivalents, and quality factors at different depths in a water sphere in an imaginary spacecraft during solar minimum in a geosynchronous orbit. The calculations were performed with the GEANT4 Monte Carlo (MC) code using both the binary cascade (BIC) model, which is part of the standard GEANT4 package, and the JQMD model, which is used in the particle and heavy ion transport code PHITS GEANT4.

Cost of goods sold and total cost of delivery for oral and parenteral vaccine packaging formats.

PubMed

Sedita, Jeff; Perrella, Stefanie; Morio, Matt; Berbari, Michael; Hsu, Jui-Shan; Saxon, Eugene; Jarrahian, Courtney; Rein-Weston, Annie; Zehrung, Darin

2018-03-14

Despite limitations of glass packaging for vaccines, the industry has been slow to implement alternative formats. Polymer containers may address many of these limitations, such as breakage and delamination. However, the ability of polymer containers to achieve cost of goods sold (COGS) and total cost of delivery (TCOD) competitive with that of glass containers is unclear, especially for cost-sensitive low- and lower-middle-income countries. COGS and TCOD models for oral and parenteral vaccine packaging formats were developed based on information from subject matter experts, published literature, and Kenya's comprehensive multiyear plan for immunization. Rotavirus and inactivated poliovirus vaccines (IPV) were used as representative examples of oral and parenteral vaccines, respectively. Packaging technologies evaluated included glass vials, blow-fill-seal (BFS) containers, preformed polymer containers, and compact prefilled auto-disable (CPAD) devices in both BFS and preformed formats. For oral vaccine packaging, BFS multi-monodose (MMD) ampoules were the least expensive format, with a COGS of $0.12 per dose. In comparison, oral single-dose glass vials had a COGS of $0.40. BFS MMD ampoules had the lowest TCOD of oral vaccine containers at $1.19 per dose delivered, and ten-dose glass vials had a TCOD of $1.61 per dose delivered. For parenteral vaccines, the lowest COGS was achieved with ten-dose glass vials at $0.22 per dose. In contrast, preformed CPAD devices had the highest COGS at $0.60 per dose. Ten-dose glass vials achieved the lowest TCOD of the parenteral vaccine formats at $1.56 per dose delivered. Of the polymer containers for parenteral vaccines, BFS MMD ampoules achieved the lowest TCOD at $1.89 per dose delivered, whereas preformed CPAD devices remained the most expensive format, at $2.25 per dose delivered. Given their potential to address the limitations of glass and reduce COGS and TCOD, polymer containers deserve further consideration as alternative approaches for vaccine packaging. Copyright © 2018 PATH. Published by Elsevier Ltd.. All rights reserved.

A comparison of six software packages for evaluation of solid lung nodules using semi-automated volumetry: what is the minimum increase in size to detect growth in repeated CT examinations.

PubMed

de Hoop, Bartjan; Gietema, Hester; van Ginneken, Bram; Zanen, Pieter; Groenewegen, Gerard; Prokop, Mathias

2009-04-01

We compared interexamination variability of CT lung nodule volumetry with six currently available semi-automated software packages to determine the minimum change needed to detect the growth of solid lung nodules. We had ethics committee approval. To simulate a follow-up examination with zero growth, we performed two low-dose unenhanced CT scans in 20 patients referred for pulmonary metastases. Between examinations, patients got off and on the table. Volumes of all pulmonary nodules were determined on both examinations using six nodule evaluation software packages. Variability (upper limit of the 95% confidence interval of the Bland-Altman plot) was calculated for nodules for which segmentation was visually rated as adequate. We evaluated 214 nodules (mean diameter 10.9 mm, range 3.3 mm-30.0 mm). Software packages provided adequate segmentation in 71% to 86% of nodules (p < 0.001). In case of adequate segmentation, variability in volumetry between scans ranged from 16.4% to 22.3% for the various software packages. Variability with five to six software packages was significantly less for nodules >or=8 mm in diameter (range 12.9%-17.1%) than for nodules <8 mm (range 18.5%-25.6%). Segmented volumes of each package were compared to each of the other packages. Systematic volume differences were detected in 11/15 comparisons. This hampers comparison of nodule volumes between software packages.

Application of the Scoping of Options and Analyzing Risk Model (SOAR) in the Modeling of Radionuclide Movement and Dose Calculation for a Hypothetical Deep Geological Repository for Nuclear Fuel Wastes

NASA Astrophysics Data System (ADS)

Lei, S.; Osborne, P.

2016-12-01

The Scoping of Options and Analyzing Risk (SOAR) model was developed by the U.S. Nuclear Regulatory Commission staff to assist in their evaluation of potential high-level radioactive waste disposal options. It is a 1-D contaminant transport code that contains a biosphere module to calculate mass fluxes and radiation dose to humans. As part of the Canadian Nuclear Safety Commission (CNSC)'s Coordinated Assessment Program to assist with the review of proposals for deep geological repositories (DGR's) for nuclear fuel wastes, CNSC conducted a research project to find out whether SOAR can be used by CNSC staff as an independent scoping tool to assist review of proponents' submissions related to safety assessment for DGRs. In the research, SOAR was applied to the post-closure safety assessment for a hypothetical DGR in sedimentary rock, as described in the 5th Case Study report by the Nuclear Waste Management Organization (NWMO) of Canada (2011). The report contains, among others, modeling of transport and releases of radionuclides at various locations within the geosphere and the radiation dose to humans over a period of one million years. One aspect covered was 1-D modeling of various scenarios and sensitivity cases with both deterministic and probabilistic approaches using SYVAC3-CC4, which stands for Systems Variability Analysis Code (generation 3, Canadian Concept generation 4), developed by Atomic Energy of Canada Limited (Kitson et al., 2000). Radionuclide fluxes and radiation dose to the humans calculated using SOAR were compared with that from NWMO's modeling. Overall, the results from the two models were similar, although SOAR gave lower mass fluxes and peak dose, mainly due to differences in modeling the waste package configurations. Sensitivity analyses indicate that both models are most sensitive to the diffusion coefficient of the geological media. The research leads to the conclusion that SOAR is a robust, user friendly, and flexible scoping tool that CNSC staff may use for safety assessments; however, some improvements may be needed, such as including dose contributions from other pathways in addition to drinking water and being more flexible for modeling different waste package configurations.

Validation of a commercial TPS based on the VMC(++) Monte Carlo code for electron beams: commissioning and dosimetric comparison with EGSnrc in homogeneous and heterogeneous phantoms.

PubMed

Ferretti, A; Martignano, A; Simonato, F; Paiusco, M

2014-02-01

The aim of the present work was the validation of the VMC(++) Monte Carlo (MC) engine implemented in the Oncentra Masterplan (OMTPS) and used to calculate the dose distribution produced by the electron beams (energy 5-12 MeV) generated by the linear accelerator (linac) Primus (Siemens), shaped by a digital variable applicator (DEVA). The BEAMnrc/DOSXYZnrc (EGSnrc package) MC model of the linac head was used as a benchmark. Commissioning results for both MC codes were evaluated by means of 1D Gamma Analysis (2%, 2 mm), calculated with a home-made Matlab (The MathWorks) program, comparing the calculations with the measured profiles. The results of the commissioning of OMTPS were good [average gamma index (γ) > 97%]; some mismatches were found with large beams (size ≥ 15 cm). The optimization of the BEAMnrc model required to increase the beam exit window to match the calculated and measured profiles (final average γ > 98%). Then OMTPS dose distribution maps were compared with DOSXYZnrc with a 2D Gamma Analysis (3%, 3 mm), in 3 virtual water phantoms: (a) with an air step, (b) with an air insert, and (c) with a bone insert. The OMTPD and EGSnrc dose distributions with the air-water step phantom were in very high agreement (γ ∼ 99%), while for heterogeneous phantoms there were differences of about 9% in the air insert and of about 10-15% in the bone region. This is due to the Masterplan implementation of VMC(++) which reports the dose as "dose to water", instead of "dose to medium". Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Risk ranking of LANL nuclear material storage containers for repackaging prioritization.

PubMed

Smith, Paul H; Jordan, Hans; Hoffman, Jenifer A; Eller, P Gary; Balkey, Simon

2007-05-01

Safe handling and storage of nuclear material at U.S. Department of Energy facilities relies on the use of robust containers to prevent container breaches and subsequent worker contamination and uptake. The U.S. Department of Energy has no uniform requirements for packaging and storage of nuclear materials other than those declared excess and packaged to DOE-STD-3013-2000. This report describes a methodology for prioritizing a large inventory of nuclear material containers so that the highest risk containers are repackaged first. The methodology utilizes expert judgment to assign respirable fractions and reactivity factors to accountable levels of nuclear material at Los Alamos National Laboratory. A relative risk factor is assigned to each nuclear material container based on a calculated dose to a worker due to a failed container barrier and a calculated probability of container failure based on material reactivity and container age. This risk-based methodology is being applied at LANL to repackage the highest risk materials first and, thus, accelerate the reduction of risk to nuclear material handlers.

An electron-beam dose deposition experiment: TIGER 1-D simulation code versus thermoluminescent dosimetry

NASA Astrophysics Data System (ADS)

Murrill, Steven R.; Tipton, Charles W.; Self, Charles T.

1991-03-01

The dose absorbed in an integrated circuit (IC) die exposed to a pulse of low-energy electrons is a strong function of both electron energy and surrounding packaging materials. This report describes an experiment designed to measure how well the Integrated TIGER Series one-dimensional (1-D) electron transport simulation program predicts dose correction factors for a state-of-the-art IC package and package/printed circuit board (PCB) combination. These derived factors are compared with data obtained experimentally using thermoluminescent dosimeters (TLD's) and the FX-45 flash x-ray machine (operated in electron-beam (e-beam) mode). The results of this experiment show that the TIGER 1-D simulation code can be used to accurately predict FX-45 e-beam dose deposition correction factors for reasonably complex IC packaging configurations.

Dosimetric results on EURECA

NASA Technical Reports Server (NTRS)

Reitz, G.

1995-01-01

Detector packages were exposed on the European Retrievable Carrier (EURECA) as part of the Biostack experiment inside the Exobiology and Radiation Assembly (ERA) and at several locations around EURECA. The packages consist of different plastic nuclear track detectors, nuclear emulsions and thermoluminescence dosimeters (TLD's). Evaluation of these detectors yields data on absorbed dose and particle and LET spectra. Preliminary results of absorbed dose measurements in the EURECA dosimeter packages are reported and compared to results of the LDEF experiments. The highest dose rate measured on EURECA is 63.3 plus or minus 0.4 mGy d(exp -1) behind a shielding thickness of 0.09 g cm(exp -2) in front of the detector package.

Calculations vs. Measurements for Remnant Dose Rates from SNS Spent Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popova, Irina I.; Gallmeier, Franz X.; Trotter, Steven M.

The Spallation Neutron Source (SNS) in Oak Ridge, Tennessee, is an accelerator driven neutron scattering facility for materials research. Presently SNS is capable to operate at 1.4 MW proton beam power incident on a mercury target with a proton beam energy of 1 GeV and 60 Hz repetition rate. SNS target system components are periodically replaced because they reach their end-of-life due to radiation induced material damage. Target vessel, which houses mercury target, is exchanged about two-three times per year and the proton beam window (PBW) is exchanged every two – three years.Each spent structure that leaves the SNS sitemore » requires supporting documentation with radionuclide inventory and dose rate prediction for the time of the transportation. Neutronics analyses are performed, assuming realistic irradiation history and decay case to ensure that the container/package, housing the structure, is compliant with the waste management regulations. Analyses are complex due to geometry, multi-code usage and following data treatment.To validate analyses, measurements of dose rates from the spent target vessel # 13 and PBW module #5 were performed. Neutronics analyses were performed to calculate residual dose rates from both structures for the time of measurements.« less

Neutron dosimetric measurements in shuttle and MIR.

PubMed

Reitz, G

2001-06-01

Detector packages consisting of thermoluminescence detectors (TLD), nuclear emulsions and plastic track detectors were exposed at identical positions inside MIR space station and on shuttle flights inside Spacelab and Spacehab during different phases of the solar cycle. The objectives of the investigations are to provide data on charge and energy spectra of heavy ions, and the contribution of events with low-energy deposit (protons, electrons, gamma, etc.) to the dose, as well as the contribution of secondaries, such as nuclear disintegration stars and neutrons. For neutron dosimetry 6LiF (TLD600) and 7LiF (TLD700) chips were used both of which have almost the same response to gamma rays but different response to neutrons. Neutrons in space are produced mainly in evaporation and knock-on processes with energies mainly of 1-10 MeV and up to several 100 MeV, respectively. The energy spectrum undergoes continuous changes toward greater depth in the attenuating material until an equilibrium is reached. In equilibrium, the spectrum is a wide continuum extending down to thermal energies to which the 6LiF is sensitive. Based on the difference of absorbed doses in the 6LiF and 7LiF chips, thermal neutron fluxes from 1 to 2.3 cm-2 s-1 are calculated using the assumption that the maximum induced dose in TLD600 for 1 neutron cm-2 is 1.6 x 10(-10) Gy (Horowitz and Freeman, Nucl. Instr. and Meth. 157 (1978) 393). It is assumed that the flux of high-energy neutrons is at least of that quantity. Tissue doses were calculated taking as a mean ambient absorbed dose per neutron 6 x10(-12) Gy cm2 (for a10 MeV neutron). The neutron equivalent doses for the above-mentioned fluxes are 52 micro Gy d-1 and 120 micro Gy d-1. In recent experiments, a personal neutron dosimeter was integrated into the dosimeter packages. First results of this dosimeter which is based on nuclear track detectors with converter foils are reported. For future measurements, a scintillator counter with anticoincidence logic is under development. c2001 Elsevier Science Ltd. All rights reserved.

A new approach to integrate GPU-based Monte Carlo simulation into inverse treatment plan optimization for proton therapy.

PubMed

Li, Yongbao; Tian, Zhen; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

2017-01-07

Monte Carlo (MC)-based spot dose calculation is highly desired for inverse treatment planning in proton therapy because of its accuracy. Recent studies on biological optimization have also indicated the use of MC methods to compute relevant quantities of interest, e.g. linear energy transfer. Although GPU-based MC engines have been developed to address inverse optimization problems, their efficiency still needs to be improved. Also, the use of a large number of GPUs in MC calculation is not favorable for clinical applications. The previously proposed adaptive particle sampling (APS) method can improve the efficiency of MC-based inverse optimization by using the computationally expensive MC simulation more effectively. This method is more efficient than the conventional approach that performs spot dose calculation and optimization in two sequential steps. In this paper, we propose a computational library to perform MC-based spot dose calculation on GPU with the APS scheme. The implemented APS method performs a non-uniform sampling of the particles from pencil beam spots during the optimization process, favoring those from the high intensity spots. The library also conducts two computationally intensive matrix-vector operations frequently used when solving an optimization problem. This library design allows a streamlined integration of the MC-based spot dose calculation into an existing proton therapy inverse planning process. We tested the developed library in a typical inverse optimization system with four patient cases. The library achieved the targeted functions by supporting inverse planning in various proton therapy schemes, e.g. single field uniform dose, 3D intensity modulated proton therapy, and distal edge tracking. The efficiency was 41.6  ±  15.3% higher than the use of a GPU-based MC package in a conventional calculation scheme. The total computation time ranged between 2 and 50 min on a single GPU card depending on the problem size.

A new approach to integrate GPU-based Monte Carlo simulation into inverse treatment plan optimization for proton therapy

NASA Astrophysics Data System (ADS)

Li, Yongbao; Tian, Zhen; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

2017-01-01

Monte Carlo (MC)-based spot dose calculation is highly desired for inverse treatment planning in proton therapy because of its accuracy. Recent studies on biological optimization have also indicated the use of MC methods to compute relevant quantities of interest, e.g. linear energy transfer. Although GPU-based MC engines have been developed to address inverse optimization problems, their efficiency still needs to be improved. Also, the use of a large number of GPUs in MC calculation is not favorable for clinical applications. The previously proposed adaptive particle sampling (APS) method can improve the efficiency of MC-based inverse optimization by using the computationally expensive MC simulation more effectively. This method is more efficient than the conventional approach that performs spot dose calculation and optimization in two sequential steps. In this paper, we propose a computational library to perform MC-based spot dose calculation on GPU with the APS scheme. The implemented APS method performs a non-uniform sampling of the particles from pencil beam spots during the optimization process, favoring those from the high intensity spots. The library also conducts two computationally intensive matrix-vector operations frequently used when solving an optimization problem. This library design allows a streamlined integration of the MC-based spot dose calculation into an existing proton therapy inverse planning process. We tested the developed library in a typical inverse optimization system with four patient cases. The library achieved the targeted functions by supporting inverse planning in various proton therapy schemes, e.g. single field uniform dose, 3D intensity modulated proton therapy, and distal edge tracking. The efficiency was 41.6  ±  15.3% higher than the use of a GPU-based MC package in a conventional calculation scheme. The total computation time ranged between 2 and 50 min on a single GPU card depending on the problem size.

A New Approach to Integrate GPU-based Monte Carlo Simulation into Inverse Treatment Plan Optimization for Proton Therapy

PubMed Central

Li, Yongbao; Tian, Zhen; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

2016-01-01

Monte Carlo (MC)-based spot dose calculation is highly desired for inverse treatment planning in proton therapy because of its accuracy. Recent studies on biological optimization have also indicated the use of MC methods to compute relevant quantities of interest, e.g. linear energy transfer. Although GPU-based MC engines have been developed to address inverse optimization problems, their efficiency still needs to be improved. Also, the use of a large number of GPUs in MC calculation is not favorable for clinical applications. The previously proposed adaptive particle sampling (APS) method can improve the efficiency of MC-based inverse optimization by using the computationally expensive MC simulation more effectively. This method is more efficient than the conventional approach that performs spot dose calculation and optimization in two sequential steps. In this paper, we propose a computational library to perform MC-based spot dose calculation on GPU with the APS scheme. The implemented APS method performs a non-uniform sampling of the particles from pencil beam spots during the optimization process, favoring those from the high intensity spots. The library also conducts two computationally intensive matrix-vector operations frequently used when solving an optimization problem. This library design allows a streamlined integration of the MC-based spot dose calculation into an existing proton therapy inverse planning process. We tested the developed library in a typical inverse optimization system with four patient cases. The library achieved the targeted functions by supporting inverse planning in various proton therapy schemes, e.g. single field uniform dose, 3D intensity modulated proton therapy, and distal edge tracking. The efficiency was 41.6±15.3% higher than the use of a GPU-based MC package in a conventional calculation scheme. The total computation time ranged between 2 and 50 min on a single GPU card depending on the problem size. PMID:27991456

Results of dosimetric measurements in space missions

NASA Astrophysics Data System (ADS)

Reitz, G.; Beaujean, R.; Heilmann, C.; Kopp, J.; Leicher, M.; Strauch, K.

Detector packages consisting of plastic nuclear track detectors, nuclear emulsions, and thermoluminescence detectors were exposed at different locations inside the space laboratory Spacelab and at the astronauts' body and in different sections of the MIR space station. Total dose, particle fluence rate and linear energy transfer (LET) spectra of heavy ions, number of nuclear disintegrations and fast neutron fluence rates were determined of each exposure. The dose equivalent received by the Payload specialists (PSs) were calculated from the measurements, they range from 190 muSv d^-1 to 770 muSv d^-1. Finally, a preliminary investigation of results from a particle telescope of two silicon detectors, first used in the last BIORACK mission on STS 76, is reported.

SU-E-T-558: Monte Carlo Photon Transport Simulations On GPU with Quadric Geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Y; Tian, Z; Jiang, S

Purpose: Monte Carlo simulation on GPU has experienced rapid advancements over the past a few years and tremendous accelerations have been achieved. Yet existing packages were developed only in voxelized geometry. In some applications, e.g. radioactive seed modeling, simulations in more complicated geometry are needed. This abstract reports our initial efforts towards developing a quadric geometry module aiming at expanding the application scope of GPU-based MC simulations. Methods: We defined the simulation geometry consisting of a number of homogeneous bodies, each specified by its material composition and limiting surfaces characterized by quadric functions. A tree data structure was utilized tomore » define geometric relationship between different bodies. We modified our GPU-based photon MC transport package to incorporate this geometry. Specifically, geometry parameters were loaded into GPU’s shared memory for fast access. Geometry functions were rewritten to enable the identification of the body that contains the current particle location via a fast searching algorithm based on the tree data structure. Results: We tested our package in an example problem of HDR-brachytherapy dose calculation for shielded cylinder. The dose under the quadric geometry and that under the voxelized geometry agreed in 94.2% of total voxels within 20% isodose line based on a statistical t-test (95% confidence level), where the reference dose was defined to be the one at 0.5cm away from the cylinder surface. It took 243sec to transport 100million source photons under this quadric geometry on an NVidia Titan GPU card. Compared with simulation time of 99.6sec in the voxelized geometry, including quadric geometry reduced efficiency due to the complicated geometry-related computations. Conclusion: Our GPU-based MC package has been extended to support photon transport simulation in quadric geometry. Satisfactory accuracy was observed with a reduced efficiency. Developments for charged particle transport in this geometry are currently in progress.« less

Economics of botulinum toxin therapy: influence of the abobotulinumtoxinA package size on the costs of botulinum toxin therapy.

PubMed

Dressler, Dirk; Adib Saberi, Fereshte

2017-01-01

AbobotulinumtoxinA (Dysport®) was distributed for many years in vials containing 500MU (D500). Recently a new 300MU vial (D300) was additionally introduced (introduction). We wanted to explore whether more differentiated package sizes allow for more economic use of Dysport® in a large neurological botulinum toxin (BT) outpatient clinic. The study followed a retrospective chart review design based on our digital BT therapy data bank. All patients receiving Dysport® exclusively in a constant dose during the observation period (introduction ± 7 months) were included. Economic calculations are based on Dysport® prices as officially advertised in Germany. Sharing of vials between patients was not allowed. Altogether 83 patients (51 with dystonia, 25 with spasticity, 3 with hemifacial spasm, 4 with other diagnoses) were included in this study. The total amount of BT used before and after introduction was 102525MU, the amount prescribed 138000MU and 116300MU (-21700MU, -15.7%), the costs €146103 and €125250 (-€ 20853, -14.3%). The price for D500 before and after introduction was €529.36, for D300 €339.71. The D500 price for 1MU before and after introduction is €1.0587, the D300 price for 1MU €1.1324 (+ €0.073, +7.0% against D500). More flexible packaging reduces drug costs for BT therapy considerably. Introducing smaller packaging sizes is technically possible and should be encouraged. Extra costs for registration and logistics are moderate. Further cost reductions may be possible by introduction of even smaller packaging sizes. They can be calculated based on our model.

A GPU OpenCL based cross-platform Monte Carlo dose calculation engine (goMC)

NASA Astrophysics Data System (ADS)

Tian, Zhen; Shi, Feng; Folkerts, Michael; Qin, Nan; Jiang, Steve B.; Jia, Xun

2015-09-01

Monte Carlo (MC) simulation has been recognized as the most accurate dose calculation method for radiotherapy. However, the extremely long computation time impedes its clinical application. Recently, a lot of effort has been made to realize fast MC dose calculation on graphic processing units (GPUs). However, most of the GPU-based MC dose engines have been developed under NVidia’s CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a GPU OpenCL based cross-platform MC dose engine named goMC with coupled photon-electron simulation for external photon and electron radiotherapy in the MeV energy range. Compared to our previously developed GPU-based MC code named gDPM (Jia et al 2012 Phys. Med. Biol. 57 7783-97), goMC has two major differences. First, it was developed under the OpenCL environment for high code portability and hence could be run not only on different GPU cards but also on CPU platforms. Second, we adopted the electron transport model used in EGSnrc MC package and PENELOPE’s random hinge method in our new dose engine, instead of the dose planning method employed in gDPM. Dose distributions were calculated for a 15 MeV electron beam and a 6 MV photon beam in a homogenous water phantom, a water-bone-lung-water slab phantom and a half-slab phantom. Satisfactory agreement between the two MC dose engines goMC and gDPM was observed in all cases. The average dose differences in the regions that received a dose higher than 10% of the maximum dose were 0.48-0.53% for the electron beam cases and 0.15-0.17% for the photon beam cases. In terms of efficiency, goMC was ~4-16% slower than gDPM when running on the same NVidia TITAN card for all the cases we tested, due to both the different electron transport models and the different development environments. The code portability of our new dose engine goMC was validated by successfully running it on a variety of different computing devices including an NVidia GPU card, two AMD GPU cards and an Intel CPU processor. Computational efficiency among these platforms was compared.

A GPU OpenCL based cross-platform Monte Carlo dose calculation engine (goMC).

PubMed

Tian, Zhen; Shi, Feng; Folkerts, Michael; Qin, Nan; Jiang, Steve B; Jia, Xun

2015-10-07

Monte Carlo (MC) simulation has been recognized as the most accurate dose calculation method for radiotherapy. However, the extremely long computation time impedes its clinical application. Recently, a lot of effort has been made to realize fast MC dose calculation on graphic processing units (GPUs). However, most of the GPU-based MC dose engines have been developed under NVidia's CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a GPU OpenCL based cross-platform MC dose engine named goMC with coupled photon-electron simulation for external photon and electron radiotherapy in the MeV energy range. Compared to our previously developed GPU-based MC code named gDPM (Jia et al 2012 Phys. Med. Biol. 57 7783-97), goMC has two major differences. First, it was developed under the OpenCL environment for high code portability and hence could be run not only on different GPU cards but also on CPU platforms. Second, we adopted the electron transport model used in EGSnrc MC package and PENELOPE's random hinge method in our new dose engine, instead of the dose planning method employed in gDPM. Dose distributions were calculated for a 15 MeV electron beam and a 6 MV photon beam in a homogenous water phantom, a water-bone-lung-water slab phantom and a half-slab phantom. Satisfactory agreement between the two MC dose engines goMC and gDPM was observed in all cases. The average dose differences in the regions that received a dose higher than 10% of the maximum dose were 0.48-0.53% for the electron beam cases and 0.15-0.17% for the photon beam cases. In terms of efficiency, goMC was ~4-16% slower than gDPM when running on the same NVidia TITAN card for all the cases we tested, due to both the different electron transport models and the different development environments. The code portability of our new dose engine goMC was validated by successfully running it on a variety of different computing devices including an NVidia GPU card, two AMD GPU cards and an Intel CPU processor. Computational efficiency among these platforms was compared.

Dill: an algorithm and a symbolic software package for doing classical supersymmetry calculations

NASA Astrophysics Data System (ADS)

Luc̆ić, Vladan

1995-11-01

An algorithm is presented that formalizes different steps in a classical Supersymmetric (SUSY) calculation. Based on the algorithm Dill, a symbolic software package, that can perform the calculations, is developed in the Mathematica programming language. While the algorithm is quite general, the package is created for the 4 - D, N = 1 model. Nevertheless, with little modification, the package could be used for other SUSY models. The package has been tested and some of the results are presented.

MO-H-19A-03: Patient Specific Bolus with 3D Printing Technology for Electron Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, W; Swann, B; Siderits, R

2014-06-15

Purpose: Bolus is widely used in electron radiotherapy to achieve desired dose distribution. 3D printing technologies provide clinicians with easy access to fabricate patient specific bolus accommodating patient body surface irregularities and tissue inhomogeneity. This study presents the design and the clinical workflow of 3D printed bolus for patient electron therapy in our clinic. Methods: Patient simulation CT images free of bolus were exported from treatment planning system (TPS) to an in-house developed software package. Bolus with known material properties was designed in the software package and then exported back to the TPS as a structure. Dose calculation was carriedmore » out to examine the coverage of the target. After satisfying dose distribution was achieved, the bolus structure was transferred in Standard Tessellation Language (STL) file format for the 3D printer to generate the machine codes for printing. Upon receiving printed bolus, a quick quality assurance was performed with patient resimulated with bolus in place to verify the bolus dosimetric property before treatment started. Results: A patient specific bolus for electron radiotherapy was designed and fabricated in Form 1 3D printer with methacrylate photopolymer resin. Satisfying dose distribution was achieved in patient with bolus setup. Treatment was successfully finished for one patient with the 3D printed bolus. Conclusion: The electron bolus fabrication with 3D printing technology was successfully implemented in clinic practice.« less

User’s guide for MapMark4—An R package for the probability calculations in three-part mineral resource assessments

USGS Publications Warehouse

Ellefsen, Karl J.

2017-06-27

MapMark4 is a software package that implements the probability calculations in three-part mineral resource assessments. Functions within the software package are written in the R statistical programming language. These functions, their documentation, and a copy of this user’s guide are bundled together in R’s unit of shareable code, which is called a “package.” This user’s guide includes step-by-step instructions showing how the functions are used to carry out the probability calculations. The calculations are demonstrated using test data, which are included in the package.

Dose-to-dose variations with single packages of counterfeit medicines and adulterated dietary supplements as a potential source of false negatives and inaccurate health risk assessments.

PubMed

Venhuis, B J; Zwaagstra, M E; Keizers, P H J; de Kaste, D

2014-02-01

In this report, we show three examples of how the variability in dose units in single packages of counterfeit medicines and adulterated dietary supplements may contribute to a false negative screening result and inaccurate health risk assessments. We describe a counterfeit Viagra 100mg blister pack and a box of an instant coffee both containing dose units with and without an active pharmaceutical ingredient (API). We also describe a purportedly herbal slimming product with capsules that mutually differed in API and impurities. The adulterated dietary supplements contained sibutramine, benzyl-sibutramine, N-desmethyl-sibutramine (DMS), N,N-didesmethyl-sibutramine (DDMS) and several other related impurities. Counterfeit medicines and adulterated dietary supplements are a health risk because their quality is unreliable. Health risks are even greater when such unreliability extends to fundamental differences between dose units in one package. Because dose-to-dose variability for these products is unpredictable, the confidence interval of a sample size is unknown. Consequently, the analyses of a selection of dose units may not be representative for the package. In the worst case, counterfeit or unauthorised medicines are not recognised as such or a health risk is not identified. In order to reduce erroneous results particular care should be taken when analysing a composite of dose units, when finding no API in a dietary supplement and when finding conformity in a suspect counterfeit medicine. Copyright © 2013 Elsevier B.V. All rights reserved.

Unit-dose packaged drugs for treating malaria.

PubMed

Orton, L; Barnish, G

2005-04-18

Unit-dose packaging of antimalarial drugs may improve malaria cure by making it easier for patients to take their treatment correctly. To summarize the effects of unit-dose packaged treatment on cure and treatment adherence in people with uncomplicated malaria. We searched the Cochrane Infectious Diseases Group Specialized Register (November 2004), CENTRAL (The Cochrane Library Issue 4, 2004), MEDLINE (1966 to November 2004), EMBASE (1980 to November 2004), LILACS (November 2004), conference proceedings, and reference lists of articles. We also contacted pharmaceutical companies, organizations, and researchers in the field. Randomized controlled trials (RCTs), cluster-RCTs, quasi-RCTs, and controlled before-and-after studies of unit-dose packaged drugs for treating uncomplicated malaria. We independently assessed study eligibility and methodological quality, and extracted data for an intention to treat analysis, where possible. We combined binary data using relative risk (RR) and the fixed-effect model, and presented them with 95% confidence intervals (CI). We attempted to contact study authors for additional information. Three quasi-RCTs (895 participants) and one cluster-RCT (6 health facilities) met the inclusion criteria. Trials were of poor methodological quality, and none adequately assessed treatment failure. Unit-dose packaged drugs (in conjunction with prescriber training and patient information) appeared to be associated with higher participant-reported treatment adherence in all trials.A meta-analysis of two trials (596 participants) showed that participant-reported treatment adherence was higher with blister-packed tablets compared with tablets in paper envelopes (RR 1.18, 1.12 to 1.25). Two trials using tablets in sectioned polythene bags as the intervention also noted an increase in participant-reported treatment adherence: the cluster-RCT (6 clusters) compared it with tablets in paper envelopes, and the other trial compared it with syrup in bottles (RR 2.15, 1.76 to 2.61; 299 participants). There is insufficient evidence to determine the effect of unit-dose packaged antimalarial drugs on treatment failure. Unit-dose packaging supported by prescriber training and patient information appears to improve participant-reported treatment adherence, but these data come from trials with methodological limitations.

Comparison between Measured and Simulated Radiation Doses in the Matoroshka-R Spherical phantom Experiment#1 and Area Monitoring aboard International Space Station using PADLES from May - Sep. 2012

NASA Astrophysics Data System (ADS)

Nagamatsu, Aiko; Tolochek, Raisa; Shurshakov, Vyacheslav; Nikolaev, Igor; Tawara, Hiroko; Kitajo, Keiichi; Shimada, Ken

The measurement of radiation environmental parameters in space is essential to support radiation risk assessments for astronauts and establish a benchmark for space radiation models for present and future human space activities. Since Japanese Experiment Module ‘KIBO’ was attached to the International Space Station (ISS) in 2008, we have been performing continuous space radiation dosimetery using a PADLES (Passive Dosimeter for Life-Science Experiments in Space) consisting of CR-39 PNTDs (Plastic Nuclear track detectors) and TLD-MSOs (Mg2SiO4:Tb) for various space experiments onboard the ‘KIBO’ part of the ISS. The MATROSHKA-R experiments aims to verify of dose distributions in a human body during space flight. The phantom consists of tissue equivalent material covered by a poncho jacket with 32 pockets on the surface. 20 container rods with dosimeters can be struck into the spherical phantom. Its diameter is 370 mm and it is 32 kg in weight. The first experiment onboard the KIBO at Forward No.2 area (JPM1F2 Rack2) was conducted over 114 days from 21 May to 12 September 2012 (the installation schedule inside the phantom) on the way to solar cycle 24th upward curve. 16 PADLES packages were deployed into 16 poncho pockets on the surface of the spherical phantom. Another 12 PADLES packages were deployed inside 4 rods (3 packages per rod in the outer, middle and inner side). Area monitoring in the KIBO was conducted in the same period (Area PADLES series #8 from 15 May to 16 September, 2012). Absorbed doses were measured at 17 area monitoring points in the KIBO and 28 locations (16 packages in poncho pockets and 12 inside 4 rods) in the phantom. The maximum value measured with the PADLES in the poncho pockets on the surface of the spherical phantom facing the outer wall was 0.43 mGy/day and the minimum value measured with the PADLES in the poncho pockets on the surface of the spherical phantom facing the KIBO interior was 0.30 mGy/day. The maximum absorbed doses measured inside rods was 0.28 mGy/day and the minimum value was 0.19 mGy/day. This indicates doses measured from the dosimeters placed in the outer side of each rod are relatively high compared to the doses placed in the center of rod. At this time, we also would like to show the preliminary results of comparative study between measured and Simulated Radiation Doses using the Particle and Heavy Ion Transport code System (PHITS) calculations with well developed shielding model of the KIBO and numerical spherical phantom inside.

DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

P. Bernot

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH andmore » log fCO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with {sup 231}Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.« less

Hidden costs of HIV treatment in Spain: inefficiency of the antiretroviral drug packaging.

PubMed

Llibre-Codina, Josep M; Andreu-Crespo, Angels; Cardona-Peitx, Gloria; Sala-Piñol, Ferran; Clotet-Sala, Bonaventura; Bonafont-Pujol, Xavier

2014-01-01

Antiretroviral drugs in Spain are delivered by law only in hospital pharmacies. Commercial packages meet variable quality standards when dispensed drugs are returned due to treatment changes or adherence problems Nearly 20-25% of the initial regimens will be changed at 48 weeks for different reasons. We evaluated the economic impact on public health system of the inability of using returned drugs due to inefficient packaging. We defined socially efficient packaging as the best adapted one to being delivered in unit dose to outpatients and classified: Class A - Drug packed in unit doses with complete info (name of drug, dosage in mg, lot, and expiring date) in each unit, maintaining complete information of the drug if returned when the external package is opened. Class B - packed in blisters with complete info in the blister, but not in unit doses, without special conservation conditions (should be re-packed in unit doses in the pharmacy before its dispensation to assure a class A excellence). Class C - packed in plastic containers with complete info written only on a label over the container, would allow repackaging only before its initial delivery, but not when returned. Class D - drug packed in plastic containers with manufacturer's warning that the product cannot be placed outside of the original package due to special conditions of conservation (fridge, humidity) that doesn't allow a unit dose repackaging or reusing an opened container. We analysed a 12-month period (July 2011-June 2012) in a hospital-based HIV outpatient pharmacy that serves 2413 treated individuals. Patients generated 23,574 visits to pharmacy, and received 48,325 drug packages, with 2.529.137 pills delivered. The patients suffered 1051 treatment changes for any reason. A total amount of 122.945€ in treatment were returned to pharmacy in opened packages during the study period. 47.139.91€ would be totally lost, mainly due to being packaged in class C and D boxes, the equivalent of treating 78 patients with rilpivirine/TDF/FTC during 1 month. Class A and B packages in bad condition represented only 1.1% of the cost. However, 75.805€ came from returned packages in good condition that could potentially be reused. Most of the treatment changes were not foreseeable. A significant economic budget is lost through socially inefficient antiretroviral packages. Newer treatments are packaged in C and D categories, therefore maintaining these hidden costs in the near future. Any improvement in the excellence of packaging by the manufacturer, and favouring the choice of drugs supplied through efficient packages (when efficacy, toxicity and convenience are similar) should minimize the treatment expenditures paid by national health budgets.

Combined experimental and Monte Carlo verification of brachytherapy plans for vaginal applicators

NASA Astrophysics Data System (ADS)

Sloboda, Ron S.; Wang, Ruqing

1998-12-01

Dose rates in a phantom around a shielded and an unshielded vaginal applicator containing Selectron low-dose-rate sources were determined by experiment and Monte Carlo simulation. Measurements were performed with thermoluminescent dosimeters in a white polystyrene phantom using an experimental protocol geared for precision. Calculations for the same set-up were done using a version of the EGS4 Monte Carlo code system modified for brachytherapy applications into which a new combinatorial geometry package developed by Bielajew was recently incorporated. Measured dose rates agree with Monte Carlo estimates to within 5% (1 SD) for the unshielded applicator, while highlighting some experimental uncertainties for the shielded applicator. Monte Carlo calculations were also done to determine a value for the effective transmission of the shield required for clinical treatment planning, and to estimate the dose rate in water at points in axial and sagittal planes transecting the shielded applicator. Comparison with dose rates generated by the planning system indicates that agreement is better than 5% (1 SD) at most positions. The precision thermoluminescent dosimetry protocol and modified Monte Carlo code are effective complementary tools for brachytherapy applicator dosimetry.

CRP - VD Tube & Closure -  Unit Non-Reclosable Packaging Rigid

EPA Pesticide Factsheets

This is a unit-dose non-reclosable rigid package. The package consists of a tube and a closure that is permanently attached to the tube neck. The package is opened by pushing down on the closure and simultaneously turning it counterclockwise.

SU-C-12A-05: Radiation Dose in High-Pitch Pediatric Cardiac CTA: Correlation Between Lung Dose and CTDIvol, DLP, and Size Specific Dose Estimates (SSDE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J; Kino, A; Newman, B

2014-06-01

Purpose: To investigate the radiation dose for pediatric high pitch cardiac CTA Methods: A total of 14 cases were included in this study, with mean age of 6.2 years (ranges from 2 months to 15 years). Cardiac CTA was performed using a dual-source CT system (Definition Flash, Siemens). Tube voltage (70, 80 and 100kV) was chosen based on patient weight. All patients were scanned using a high-pitch spiral mode (pitch ranges from 2.5 to 3) with tube current modulation technique (CareDose4D, Siemens). For each case, the three dimensional dose distributions were calculated using a Monte Carlo software package (IMPACT-MC, CTmore » Image GmbH). Scanning parameters of each exam, including tube voltage, tube current, beamshaping filters, beam collimation, were defined in the Monte Carlo calculation. Tube current profile along projection angles was obtained from projection data of each tube, which included data within the over-scanning range along z direction. The volume of lungs was segmented out with CT images (3DSlicer). Lung doses of all patients were calculated and compared with CTDIvol, DLP, and SSDE. Results: The average (range) of CTDIvol, DLP and SSDE of all patients was 1.19 mGy (0.58 to 3.12mGy), 31.54 mGy*cm (12.56 to 99 mGy*cm), 2.26 mGy (1.19 to 6.24 mGy), respectively. Radiation dose to the lungs ranged from 0.83 to 4.18 mGy. Lung doses correlated with CTDIvol, DLP and SSDE with correlation coefficients(k) at 0.98, 0.93, and 0.99. However, for the cases with CTDIvol less than 1mGy, only SSDE preserved a strong correlation with lung doses (k=0.83), while much weaker correlations were found for CTDIvol (k=0.29) and DLP (k=-0.47). Conclusion: Lung doses to pediatric patients during Cardiac CTA were estimated. SSDE showed the most robust correlation with lung doses in contrast to CTDIvol and DLP.« less

Naval Waste Package Design Sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

T. Schmitt

2006-12-13

The purpose of this calculation is to determine the sensitivity of the structural response of the Naval waste packages to varying inner cavity dimensions when subjected to a comer drop and tip-over from elevated surface. This calculation will also determine the sensitivity of the structural response of the Naval waste packages to the upper bound of the naval canister masses. The scope of this document is limited to reporting the calculation results in terms of through-wall stress intensities in the outer corrosion barrier. This calculation is intended for use in support of the preliminary design activities for the license applicationmore » design of the Naval waste package. It examines the effects of small changes between the naval canister and the inner vessel, and in these dimensions, the Naval Long waste package and Naval Short waste package are similar. Therefore, only the Naval Long waste package is used in this calculation and is based on the proposed potential designs presented by the drawings and sketches in References 2.1.10 to 2.1.17 and 2.1.20. All conclusions are valid for both the Naval Long and Naval Short waste packages.« less

21 CFR 1314.110 - Reports for mail-order sales.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Administration, submit the report in electronic form, either via computer disk or direct electronic data... units (e.g., 100 doses per package); (11) Package type (blister pack, etc.); (12) Number of packages...

21 CFR 1314.110 - Reports for mail-order sales.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Administration, submit the report in electronic form, either via computer disk or direct electronic data... units (e.g., 100 doses per package); (11) Package type (blister pack, etc.); (12) Number of packages...

21 CFR 1314.110 - Reports for mail-order sales.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Administration, submit the report in electronic form, either via computer disk or direct electronic data... units (e.g., 100 doses per package); (11) Package type (blister pack, etc.); (12) Number of packages...

21 CFR 1314.110 - Reports for mail-order sales.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Administration, submit the report in electronic form, either via computer disk or direct electronic data... units (e.g., 100 doses per package); (11) Package type (blister pack, etc.); (12) Number of packages...

21 CFR 1314.110 - Reports for mail-order sales.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Administration, submit the report in electronic form, either via computer disk or direct electronic data... units (e.g., 100 doses per package); (11) Package type (blister pack, etc.); (12) Number of packages...

Total Ionizing Dose Test Report BFR92A NPN 5 GHz Wide Band Transistor from NXP

NASA Technical Reports Server (NTRS)

Phan, Anthony M.; Oldham, Timothy R.

2011-01-01

The purpose of this test was to characterize the Philips/NXP BFR92A NPN 5 gigahertz wide band silicon transistor for total dose response. This test shall serves as the radiation lot acceptance test (RLAT) for the lot date code (LDC) 1027. The BFR92A is packaged in a 3-pin plastic SOT23 package. Low dose rate (LDR/ELDRS) irradiations was performed.

Frame average optimization of cine-mode EPID images used for routine clinical in vivo patient dose verification of VMAT deliveries

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCowan, P. M., E-mail: pmccowan@cancercare.mb.ca; McCurdy, B. M. C.; Medical Physics Department, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9

Purpose: The in vivo 3D dose delivered to a patient during volumetric modulated arc therapy (VMAT) delivery can be calculated using electronic portal imaging device (EPID) images. These images must be acquired in cine-mode (i.e., “movie” mode) in order to capture the time-dependent delivery information. The angle subtended by each cine-mode EPID image during an arc can be changed via the frame averaging number selected within the image acquisition software. A large frame average number will decrease the EPID’s angular resolution and will result in a decrease in the accuracy of the dose information contained within each image. Alternatively, lessmore » EPID images acquired per delivery will decrease the overall 3D patient dose calculation time, which is appealing for large-scale clinical implementation. Therefore, the purpose of this study was to determine the optimal frame average value per EPID image, defined as the highest frame averaging that can be used without an appreciable loss in 3D dose reconstruction accuracy for VMAT treatments. Methods: Six different VMAT plans and six different SBRT-VMAT plans were delivered to an anthropomorphic phantom. Delivery was carried out on a Varian 2300ix model linear accelerator (Linac) equipped with an aS1000 EPID running at a frame acquisition rate of 7.5 Hz. An additional PC was set up at the Linac console area, equipped with specialized frame-grabber hardware and software packages allowing continuous acquisition of all EPID frames during delivery. Frames were averaged into “frame-averaged” EPID images using MATLAB. Each frame-averaged data set was used to calculate the in vivo dose to the patient and then compared to the single EPID frame in vivo dose calculation (the single frame calculation represents the highest possible angular resolution per EPID image). A mean percentage dose difference of low dose (<20% prescription dose) and high dose regions (>80% prescription dose) was calculated for each frame averaged scenario for each plan. The authors defined their unacceptable loss of accuracy as no more than a ±1% mean dose difference in the high dose region. Optimal frame average numbers were then determined as a function of the Linac’s average gantry speed and the dose per fraction. Results: The authors found that 9 and 11 frame averages were suitable for all VMAT and SBRT-VMAT treatments, respectively. This resulted in no more than a 1% loss to any of the dose region’s mean percentage difference when compared to the single frame reconstruction. The optimized number was dependent on the treatment’s dose per fraction and was determined to be as high as 14 for 12 Gy/fraction (fx), 15 for 8 Gy/fx, 11 for 6 Gy/fx, and 9 for 2 Gy/fx. Conclusions: The authors have determined an optimal EPID frame averaging number for multiple VMAT-type treatments. These are given as a function of the dose per fraction and average gantry speed. These optimized values are now used in the authors’ clinical, 3D, in vivo patient dosimetry program. This provides a reduction in calculation time while maintaining the authors’ required level of accuracy in the dose reconstruction.« less

Management of cosmic radiation exposure for aircraft crew in Japan.

PubMed

Yasuda, Hiroshi; Sato, Tatsuhiko; Yonehara, Hidenori; Kosako, Toshiso; Fujitaka, Kazunobu; Sasaki, Yasuhito

2011-07-01

The International Commission on Radiological Protection has recommended that cosmic radiation exposure of crew in commercial jet aircraft be considered as occupational exposure. In Japan, the Radiation Council of the government has established a guideline that requests domestic airlines to voluntarily keep the effective dose of cosmic radiation for aircraft crew below 5 mSv y(-1). The guideline also gives some advice and policies regarding the method of cosmic radiation dosimetry, the necessity of explanation and education about this issue, a way to view and record dose data, and the necessity of medical examination for crew. The National Institute of Radiological Sciences helps the airlines to follow the guideline, particularly for the determination of aviation route doses by numerical simulation. The calculation is performed using an original, easy-to-use program package called 'JISCARD EX' coupled with a PHITS-based analytical model and a GEANT4-based particle tracing code. The new radiation weighting factors recommended in 2007 are employed for effective dose determination. The annual individual doses of aircraft crew were estimated using this program.

Prediction of LDEF ionizing radiation environment

NASA Astrophysics Data System (ADS)

Watts, John W.; Parnell, T. A.; Derrickson, James H.; Armstrong, T. W.; Benton, E. V.

1992-01-01

The Long Duration Exposure Facility (LDEF) spacecraft flew in a 28.5 deg inclination circular orbit with an altitude in the range from 172 to 258.5 nautical miles. For this orbital altitude and inclination two components contribute most of the penetrating charge particle radiation encountered - the galactic cosmic rays and the geomagnetically trapped Van Allen protons. Where shielding is less than 1.0 g/sq cm geomagnetically trapped electrons make a significant contribution. The 'Vette' models together with the associated magnetic filed models were used to obtain the trapped electron and proton fluences. The mission proton doses were obtained from the fluence using the Burrell proton dose program. For the electron and bremsstrahlung dose we used the Marshall Space Flight Center (MSFC) electron dose program. The predicted doses were in general agreement with those measured with on-board thermoluminescent detector (TLD) dosimeters. The NRL package of programs, Cosmic Ray Effects on MicroElectronics (CREME), was used to calculate the linear energy transfer (LET) spectrum due to galactic cosmic rays (GCR) and trapped protons for comparison with LDEF measurements.

One- and two-dimensional search of an equation of state using a newly released 2DRoptimize package

NASA Astrophysics Data System (ADS)

Jamal, M.; Reshak, A. H.

2018-05-01

A new package called 2DRoptimize has been released for performing two-dimensional searches of the equation of state (EOS) for rhombohedral, tetragonal, and hexagonal compounds. The package is compatible and available with the WIEN2k package. The 2DRoptimize package performs a convenient volume and c/a structure optimization. First, the package finds the best value for c/a and the associated energy for each volume. In the second step, it calculates the EoS. The package then finds the equation of the c/a ratio vs. volume to calculate the c/a ratio at the optimized volume. In the last stage, by using the optimized volume and c/a ratio, the 2DRoptimize package calculates a and c lattice constants for tetragonal and hexagonal compounds, as well as the a lattice constant with the α angle for rhombohedral compounds. We tested our new package based on several hexagonal, tetragonal, and rhombohedral structures, and the 2D search results for the EOS showed that this method is more accurate than 1D search. Our results agreed very well with the experimental data and they were better than previous theoretical calculations.

EFFECT OF GAMMA RADIATION, CHEMICAL, AND PACKAGING TREATMENTS ON REFRIGERATED LIFE OF STRAWBERRIES AND SWEET CHERRIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, G.M.; Salunkhe, D.K.

1963-06-01

After preirradiation chemical treatments and/or packaging in films, the fruits were sealed in perforated cans and irradiated at the Materials Test Reactor Station, Arco, Idaho, with spent-fuel rods of U/sup 235/. The doses were: strawberries 1, 2, and 3 x 10/sup 5/ rad; and cherries 2, 3, and 4 x 10/sup 5/ rad. Fruits were aerated during irradiation and then placed in storage at 40 deg F and 80% relative humidity for various periods. The cans were then opened; the percentage of marketable fruits was calculated, and fungi infecting the fruits were identified. The following results were obtained with strawberries.more » A dose of 2 x 10/sup 5/ rad was optimum for radiopasteurization; shelf-life was extentded approximates 15 days at tissue caused the berries to have a spongy, water-soaked texture. Captan proved a better fungus-inhibiting chemical than potassium sorbate when used with radiation. Hormodendrum and Botryis were the most common fungi; Penicillium was killed in all irradiated treatments. Varieties such as Kasuga, Lindalicious, and Sparkle, when harvested at the firm- ripe stage of maturity and then irradiated kept better tham other varieties. With sweet cherries it was found that a dose of 3 x 10/sup 6/ rad was effective in extending shelf-life beyond 30 days. Cherries turned brown at the high (4 x 10/sup 5/-rad) dose; however, pigment development and ripening were progressively retarded in all irradiated samples. Fungus control was better with Myprozine, captan, and Mycostatin than with other chemicals used with radiation. Storage life increased significantly when Mylar packaging was combined with radiation and chemical treatments. Alternaria was the most prevalent fungus growth; Penicillium was not observed. Bing, Lambert, and Windsor varieties responded better to radiopasteurization than did Napoleon. With some varieties of cherries, deterioration of the fruit was greater after low doses tham in the absence of irradiation, which indicates that radiation causes certain physical or chemical changes in some varieties thus enabling fungi to grow readily. At lower doses, this effect apparently fosters fungus growth sufficiently to more than compensate for the fewer organisms present initially. At higher radiation doses, the probability of eliminating all fungi increases, and more fruits may be totally free of fungus regardless of growth-promoting factors. It appeared that Penicillium mold is inhibited by gamma radiation, and that the main causes of decay at higher doses were the multicellular-spored fungi, which have greater resistance to gamma radiation than the unicellular conidia of Penicillium. (BBB)« less

ADVANTG Shielding Analysis for Closure Operations in an Open-Mode Repository

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bevill, Aaron M; Radulescu, Georgeta; Scaglione, John M

2013-01-01

en-mode repository concepts could require worker entry into access drifts after placement of fuel casks in order to perform activities related to backfill, plug emplacement, routine maintenance, or performance confirmation. An ideal emplacement-drift shielding configuration would minimize dose to workers while maximizing airflow through the emplacement drifts. This paper presents a preliminary investigation of the feasibility and effectiveness of radiation shielding concepts that could be employed to facilitate worker operations in an open-mode repository. The repository model for this study includes pressurized-water reactor fuel assemblies (60 GWd/MTU burnup, 40 year post-irradiation cooldown) in packages of 32 assemblies. The closest fuelmore » packages are 5 meters from dosimetry voxels in the access drift. The unshielded dose to workers in the access drift is 73.7 rem/hour. Prior work suggests that open-mode repository concepts similar to this one would require 15 m3/s of ventilation airflow. Shielding concepts considered here include partial concrete plugs, labyrinthine shields, and stainless steel photon attenuator grids. Maximum dose to workers in the access drift was estimated for each shielding concept using MCNP5 with variance reduction parameters generated by ADVANTG. Because airflow through the shielding is important for open-mode repositories, a semi-empirical estimate of the head loss due to each shielding configuration was also calculated. Airflow and shielding performance vary widely among the proposed shielding configurations. Although the partial plug configuration had the best airflow performance, it allowed dose rates 1500 greater than the specified target. Labyrinthine shielding concepts yield doses on the order of 1 mrem/hour with configurations that impose 3 to 11 J/kg head loss. Adding 1 cm lead lining to the airflow channels of labyrinthine designs further reduces the worker dose by 65% to 95%. Photon-attenuator concepts may reduce worker dose to as low as 29 mrem/hour with head loss on the order of 1.9 J/kg.« less

Radiolysis products and sensory properties of electron-beam-irradiated high-barrier food-packaging films containing a buried layer of recycled low-density polyethylene.

PubMed

Chytiri, S D; Badeka, A V; Riganakos, K A; Kontominas, M G

2010-04-01

The aim was to study the effect of electron-beam irradiation on the production of radiolysis products and sensory changes in experimental high-barrier packaging films composed of polyamide (PA), ethylene-vinyl alcohol (EVOH) and low-density polyethylene (LDPE). Films contained a middle buried layer of recycled LDPE, while films containing 100% virgin LDPE as the middle buried layer were taken as controls. Irradiation doses ranged between zero and 60 kGy. Generally, a large number of radiolysis products were produced during electron-beam irradiation, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food 'cold pasteurization'). The quantity of radiolysis products increased with irradiation dose. There were no significant differences in radiolysis products identified between samples containing a recycled layer of LDPE and those containing virgin LDPE (all absorbed doses), indicating the 'functional barrier' properties of external virgin polymer layers. Sensory properties (mainly taste) of potable water were affected after contact with irradiated as low as 5 kGy packaging films. This effect increased with increasing irradiation dose.

Development of a software package for solid-angle calculations using the Monte Carlo method

NASA Astrophysics Data System (ADS)

Zhang, Jie; Chen, Xiulian; Zhang, Changsheng; Li, Gang; Xu, Jiayun; Sun, Guangai

2014-02-01

Solid-angle calculations play an important role in the absolute calibration of radioactivity measurement systems and in the determination of the activity of radioactive sources, which are often complicated. In the present paper, a software package is developed to provide a convenient tool for solid-angle calculations in nuclear physics. The proposed software calculates solid angles using the Monte Carlo method, in which a new type of variance reduction technique was integrated. The package, developed under the environment of Microsoft Foundation Classes (MFC) in Microsoft Visual C++, has a graphical user interface, in which, the visualization function is integrated in conjunction with OpenGL. One advantage of the proposed software package is that it can calculate the solid angle subtended by a detector with different geometric shapes (e.g., cylinder, square prism, regular triangular prism or regular hexagonal prism) to a point, circular or cylindrical source without any difficulty. The results obtained from the proposed software package were compared with those obtained from previous studies and calculated using Geant4. It shows that the proposed software package can produce accurate solid-angle values with a greater computation speed than Geant4.

Assessment of Dose to the Nursing Infant from Radionuclides in Breast Milk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leggett, Richard Wayne; Eckerman, Keith F

A computer software package was developed to predict tissue doses to an infant due to intake of radionuclides in breast milk based on bioassay measurements and exposure data for the mother. The package is intended mainly to aid in decisions regarding the safety of breast feeding by a mother who has been acutely exposed to a radionuclide during lactation or pregnancy, but it may be applied to previous intakes during the mother s adult life. The package includes biokinetic and dosimetric information needed to address intake of Co-60, Sr-90, Cs-134, Cs-137, Ir-192, Pu-238, Pu-239, Am-241, or Cf-252 by the mother.more » It has been designed so that the library of biokinetic and dosimetric files can be expanded to address a more comprehensive set of radionuclides without modifying the basic computational module. The methods and models build on the approach used in Publication 95 of the International Commission on Radiological Protection (ICRP 2004), Doses to Infants from Ingestion of Radionuclides in Mothers Milk . The software package allows input of case-specific information or judgments such as chemical form or particle size of an inhaled aerosol. The package is expected to be more suitable than ICRP Publication 95 for dose assessment for real events or realistic planning scenarios in which measurements of the mother s excretion or body burden are available.« less

Do fixed-dose combination pills or unit-of-use packaging improve adherence? A systematic review.

PubMed Central

Connor, Jennie; Rafter, Natasha; Rodgers, Anthony

2004-01-01

Adequate adherence to medication regimens is central to the successful treatment of communicable and noncommunicable disease. Fixed-dose combination pills and unit-of-use packaging are therapy-related interventions that are designed to simplify medication regimens and so potentially improve adherence. We conducted a systematic review of relevant randomized trials in order to quantify the effects of fixed-dose combination pills and unit-of-use packaging, compared with medications as usually presented, in terms of adherence to treatment and improved outcomes. Only 15 trials met the inclusion criteria; fixed-dose combination pills were investigated in three of these, while unit-of-use packaging was studied in 12 trials. The trials involved treatments for communicable diseases (n = 5), blood pressure lowering medications (n = 3), diabetic patients (n = 1), vitamin supplementation (n = 1) and management of multiple medications by the elderly (n = 5). The results of the trials suggested that there were trends towards improved adherence and/or clinical outcomes in all but three of the trials; this reached statistical significance in four out of seven trials reporting a clinically relevant or intermediate end-point, and in seven out of thirteen trials reporting medication adherence. Measures of outcome were, however, heterogeneous, and interpretation was further limited by methodological issues, particularly small sample size, short duration and loss to follow-up. Overall, the evidence suggests that fixed-dose combination pills and unit-of-use packaging are likely to improve adherence in a range of settings, but the limitations of the available evidence means that uncertainty remains about the size of these benefits. PMID:15654408

A bone marrow toxicity model for 223Ra alpha-emitter radiopharmaceutical therapy

NASA Astrophysics Data System (ADS)

Hobbs, Robert F.; Song, Hong; Watchman, Christopher J.; Bolch, Wesley E.; Aksnes, Anne-Kirsti; Ramdahl, Thomas; Flux, Glenn D.; Sgouros, George

2012-05-01

Ra-223, an α-particle emitting bone-seeking radionuclide, has recently been used in clinical trials for osseous metastases of prostate cancer. We investigated the relationship between absorbed fraction-based red marrow dosimetry and cell level-dosimetry using a model that accounts for the expected localization of this agent relative to marrow cavity architecture. We show that cell level-based dosimetry is essential to understanding potential marrow toxicity. The GEANT4 software package was used to create simple spheres representing marrow cavities. Ra-223 was positioned on the trabecular bone surface or in the endosteal layer and simulated for decay, along with the descendants. The interior of the sphere was divided into cell-size voxels and the energy was collected in each voxel and interpreted as dose cell histograms. The average absorbed dose values and absorbed fractions were also calculated in order to compare those results with previously published values. The absorbed dose was predominantly deposited near the trabecular surface. The dose cell histogram results were used to plot the percentage of cells that received a potentially toxic absorbed dose (2 or 4 Gy) as a function of the average absorbed dose over the marrow cavity. The results show (1) a heterogeneous distribution of cellular absorbed dose, strongly dependent on the position of the cell within the marrow cavity; and (2) that increasing the average marrow cavity absorbed dose, or equivalently, increasing the administered activity resulted in only a small increase in potential marrow toxicity (i.e. the number of cells receiving more than 4 or 2 Gy), for a range of average marrow cavity absorbed doses from 1 to 20 Gy. The results from the trabecular model differ markedly from a standard absorbed fraction method while presenting comparable average dose values. These suggest that increasing the amount of radioactivity may not substantially increase the risk of toxicity, a result unavailable to the absorbed fraction method of dose calculation.

A Geant4 simulation of the depth dose percentage in brain tumors treatments using protons and carbon ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diaz, José A. M., E-mail: joadiazme@unal.edu.co; Torres, D. A., E-mail: datorresg@unal.edu.co

2016-07-07

The deposited energy and dose distribution of beams of protons and carbon over a head are simulated using the free tool package Geant4 and the data analysis package ROOT-C++. The present work shows a methodology to understand the microscopical process occurring in a session of hadron-therapy using advance simulation tools.

A Web-Based System for Bayesian Benchmark Dose Estimation.

PubMed

Shao, Kan; Shapiro, Andrew J

2018-01-11

Benchmark dose (BMD) modeling is an important step in human health risk assessment and is used as the default approach to identify the point of departure for risk assessment. A probabilistic framework for dose-response assessment has been proposed and advocated by various institutions and organizations; therefore, a reliable tool is needed to provide distributional estimates for BMD and other important quantities in dose-response assessment. We developed an online system for Bayesian BMD (BBMD) estimation and compared results from this software with U.S. Environmental Protection Agency's (EPA's) Benchmark Dose Software (BMDS). The system is built on a Bayesian framework featuring the application of Markov chain Monte Carlo (MCMC) sampling for model parameter estimation and BMD calculation, which makes the BBMD system fundamentally different from the currently prevailing BMD software packages. In addition to estimating the traditional BMDs for dichotomous and continuous data, the developed system is also capable of computing model-averaged BMD estimates. A total of 518 dichotomous and 108 continuous data sets extracted from the U.S. EPA's Integrated Risk Information System (IRIS) database (and similar databases) were used as testing data to compare the estimates from the BBMD and BMDS programs. The results suggest that the BBMD system may outperform the BMDS program in a number of aspects, including fewer failed BMD and BMDL calculations and estimates. The BBMD system is a useful alternative tool for estimating BMD with additional functionalities for BMD analysis based on most recent research. Most importantly, the BBMD has the potential to incorporate prior information to make dose-response modeling more reliable and can provide distributional estimates for important quantities in dose-response assessment, which greatly facilitates the current trend for probabilistic risk assessment. https://doi.org/10.1289/EHP1289.

A geometry package for generation of input data for a three-dimensional potential-flow program

NASA Technical Reports Server (NTRS)

Halsey, N. D.; Hess, J. L.

1978-01-01

The preparation of geometric data for input to three-dimensional potential flow programs was automated and simplified by a geometry package incorporated into the NASA Langley version of the 3-D lifting potential flow program. Input to the computer program for the geometry package consists of a very sparse set of coordinate data, often with an order of magnitude of fewer points than required for the actual potential flow calculations. Isolated components, such as wings, fuselages, etc. are paneled automatically, using one of several possible element distribution algorithms. Curves of intersection between components are calculated, using a hybrid curve-fit/surface-fit approach. Intersecting components are repaneled so that adjacent elements on either side of the intersection curves line up in a satisfactory manner for the potential-flow calculations. Many cases may be run completely (from input, through the geometry package, and through the flow calculations) without interruption. Use of the package significantly reduces the time and expense involved in making three-dimensional potential flow calculations.

Drug packaging in 2013: small changes would reap big benefits.

PubMed

2014-05-01

Drug packaging is important both in protecting and informing patients. Some improvements were made in 2013, but many of the products examined by Prescrire still had poor-quality or even dangerous packaging. Problem packaging is a major concern for patients who are more vulnerable to adverse effects, particularly children and pregnant women. Several problems were noted with products intended for self-medication (umbrella brands), oral solutions sold with dosing devices, and injectable drugs. Looking back at 20 years of Red Cards that Prescrire has issued to products with dangerous packaging reveals several improvements, but too many dangers persist. Urgent action needs to be taken by regulatory agencies and drug companies: patient leaflets must be more explicit with regard to adverse effects, especially those of nonsteroidal anti-inflammatory drugs during pregnancy; accidental ingestion by children must be prevented; and companies must design safer dosing devices. Healthcare professionals and patients must remain vigilant and report all packaging issues to the relevant authorities.

Development of computational pregnant female and fetus models and assessment of radiation dose from positron-emitting tracers.

PubMed

Xie, Tianwu; Zaidi, Habib

2016-12-01

Molecular imaging using PET and hybrid (PET/CT and PET/MR) modalities nowadays plays a pivotal role in the clinical setting for diagnosis and staging, treatment response monitoring, and radiation therapy treatment planning of a wide range of oncologic malignancies. The developing embryo/fetus presents a high sensitivity to ionizing radiation. Therefore, estimation of the radiation dose delivered to the embryo/fetus and pregnant patients from PET examinations to assess potential radiation risks is highly praised. We constructed eight embryo/fetus models at various gestation periods with 25 identified tissues according to reference data recommended by the ICRP publication 89 representing the anatomy of the developing embryo/fetus. The developed embryo/fetus models were integrated into realistic anthropomorphic computational phantoms of the pregnant female and used for estimating, using Monte Carlo calculations, S-values of common positron-emitting radionuclides, organ absorbed dose, and effective dose of a number of positron-emitting labeled radiotracers. The absorbed dose is nonuniformly distributed in the fetus. The absorbed dose of the kidney and liver of the 8-week-old fetus are about 47.45 % and 44.76 % higher than the average absorbed dose of the fetal total body for all investigated radiotracers. For 18 F-FDG, the fetal effective doses are 2.90E-02, 3.09E-02, 1.79E-02, 1.59E-02, 1.47E-02, 1.40E-02, 1.37E-02, and 1.27E-02 mSv/MBq at the 8th, 10th, 15th, 20th, 25th, 30th, 35th, and 38th weeks of gestation, respectively. The developed pregnant female/fetus models matching the ICRP reference data can be exploited by dedicated software packages for internal and external dose calculations. The generated S-values will be useful to produce new standardized dose estimates to pregnant patients and embryo/fetus from a variety of positron-emitting labeled radiotracers.

Activation calculation for the dismantling and decommissioning of a light water reactor using MCNP™ with ADVANTG and ORIGEN-S

NASA Astrophysics Data System (ADS)

Schlömer, Luc; Phlippen, Peter-W.; Lukas, Bernard

2017-09-01

The decommissioning of a light water reactor (LWR), which is licensed under § 7 of the German Atomic Energy Act, following the post-operational phase requires a comprehensive licensing procedure including in particular radiation protection aspects and possible impacts to the environment. Decommissioning includes essential changes in requirements for the systems and components and will mainly lead to the direct dismantling. In this context, neutron induced activation calculations for the structural components have to be carried out to predict activities in structures and to estimate future costs for conditioning and packaging. To avoid an overestimation of the radioactive inventory and to calculate the expenses for decommissioning as accurate as possible, modern state-of-the-art Monte-Carlo-Techniques (MCNP™) are applied and coupled with present-day activation and decay codes (ORIGEN-S). In this context ADVANTG is used as weight window generator for MCNP™ i. e. as variance reduction tool to speed up the calculation in deep penetration problems. In this paper the calculation procedure is described and the obtained results are presented with a validation along with measured activities and photon dose rates measured in the post-operational phase. The validation shows that the applied calculation procedure is suitable for the determination of the radioactive inventory of a nuclear power plant. Even the measured gamma dose rates in the post-operational phase at different positions in the reactor building agree within a factor of 2 to 3 with the calculation results. The obtained results are accurate and suitable to support effectively the decommissioning planning process.

G4DARI: Geant4/GATE based Monte Carlo simulation interface for dosimetry calculation in radiotherapy.

PubMed

Slimani, Faiçal A A; Hamdi, Mahdjoub; Bentourkia, M'hamed

2018-05-01

Monte Carlo (MC) simulation is widely recognized as an important technique to study the physics of particle interactions in nuclear medicine and radiation therapy. There are different codes dedicated to dosimetry applications and widely used today in research or in clinical application, such as MCNP, EGSnrc and Geant4. However, such codes made the physics easier but the programming remains a tedious task even for physicists familiar with computer programming. In this paper we report the development of a new interface GEANT4 Dose And Radiation Interactions (G4DARI) based on GEANT4 for absorbed dose calculation and for particle tracking in humans, small animals and complex phantoms. The calculation of the absorbed dose is performed based on 3D CT human or animal images in DICOM format, from images of phantoms or from solid volumes which can be made from any pure or composite material to be specified by its molecular formula. G4DARI offers menus to the user and tabs to be filled with values or chemical formulas. The interface is described and as application, we show results obtained in a lung tumor in a digital mouse irradiated with seven energy beams, and in a patient with glioblastoma irradiated with five photon beams. In conclusion, G4DARI can be easily used by any researcher without the need to be familiar with computer programming, and it will be freely available as an application package. Copyright © 2018 Elsevier Ltd. All rights reserved.

SU-C-BRC-06: OpenCL-Based Cross-Platform Monte Carlo Simulation Package for Carbon Ion Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, N; Tian, Z; Pompos, A

2016-06-15

Purpose: Monte Carlo (MC) simulation is considered to be the most accurate method for calculation of absorbed dose and fundamental physical quantities related to biological effects in carbon ion therapy. Its long computation time impedes clinical and research applications. We have developed an MC package, goCMC, on parallel processing platforms, aiming at achieving accurate and efficient simulations for carbon therapy. Methods: goCMC was developed under OpenCL framework. It supported transport simulation in voxelized geometry with kinetic energy up to 450 MeV/u. Class II condensed history algorithm was employed for charged particle transport with stopping power computed via Bethe-Bloch equation. Secondarymore » electrons were not transported with their energy locally deposited. Energy straggling and multiple scattering were modeled. Production of secondary charged particles from nuclear interactions was implemented based on cross section and yield data from Geant4. They were transported via the condensed history scheme. goCMC supported scoring various quantities of interest e.g. physical dose, particle fluence, spectrum, linear energy transfer, and positron emitting nuclei. Results: goCMC has been benchmarked against Geant4 with different phantoms and beam energies. For 100 MeV/u, 250 MeV/u and 400 MeV/u beams impinging to a water phantom, range difference was 0.03 mm, 0.20 mm and 0.53 mm, and mean dose difference was 0.47%, 0.72% and 0.79%, respectively. goCMC can run on various computing devices. Depending on the beam energy and voxel size, it took 20∼100 seconds to simulate 10{sup 7} carbons on an AMD Radeon GPU card. The corresponding CPU time for Geant4 with the same setup was 60∼100 hours. Conclusion: We have developed an OpenCL-based cross-platform carbon MC simulation package, goCMC. Its accuracy, efficiency and portability make goCMC attractive for research and clinical applications in carbon therapy.« less

''Do-it-yourself'' software program calculates boiler efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1984-03-01

An easy-to-use software package is described which runs on the IBM Personal Computer. The package calculates boiler efficiency, an important parameter of operating costs and equipment wellbeing. The program stores inputs and calculated results for 20 sets of boiler operating data, called cases. Cases can be displayed and modified on the CRT screen through multiple display pages or copied to a printer. All intermediate calculations are performed by this package. They include: steam enthalpy; water enthalpy; air humidity; gas, oil, coal, and wood heat capacity; and radiation losses.

A simple device for efficient transfer and unit dose packaging of Xe-127: concise communication.

PubMed

Kowalsky, R J; Dalton, D R; Saylor, W L

1978-04-01

An inexpensive system has been devised for the efficient transfer of Xe-127 gas from the manufacturer's ampule into individual dose vials for patient use. By displacing the gas with an aqueous solution, the initial transfer is made from an ampule of known activity into an evacuated serum vial of predetermined volume with transfer efficiency greater than 99%. A similar principle is used to transfer Xe-127 from the stock serum vial into individual dose vials, with total xenon recovery exceeding 98%. Ability to deliver the desired activity to each vial is within 90-110% of that predicted by calculation. Reproducibility in delivering a given activity was excellent, with all vials falling between 95 and 105% of the mean activity. Stability studies showed that 94% of the Xe-127 activity can be removed from the vials with only 6% absorbed in the rubber stopper after 5 wk of storage. The device costs less than $25.00 and can be constructed easily from common laboratory materials.

Neutron-Irradiated Samples as Test Materials for MPEX

DOE PAGES

Ellis, Ronald James; Rapp, Juergen

2015-10-09

Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of themore » samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.« less

New Finsler package

NASA Astrophysics Data System (ADS)

Youssef, Nabil L.; Elgendi, S. G.

2014-03-01

The book “Handbook of Finsler geometry” has been included with a CD containing an elegant Maple package, FINSLER, for calculations in Finsler geometry. Using this package, an example concerning a Finsler generalization of Einstein’s vacuum field equations was treated. In this example, the calculation of the components of the hv-curvature of Cartan connection leads to wrong expressions. On the other hand, the FINSLER package works only in dimension four. We introduce a new Finsler package in which we fix the two problems and solve them. Moreover, we extend this package to compute not only the geometric objects associated with Cartan connection but also those associated with Berwald, Chern and Hashiguchi connections in any dimension. These improvements have been illustrated by a concrete example. Furthermore, the problem of simplifying tensor expressions is treated. This paper is intended to make calculations in Finsler geometry more easier and simpler.

Effect of gamma irradiation on physicochemical properties of commercial poly(lactic acid) clamshell for food packaging

NASA Astrophysics Data System (ADS)

Madera-Santana, Tomás J.; Meléndrez, R.; González-García, Gerardo; Quintana-Owen, Patricia; Pillai, Suresh D.

2016-06-01

Poly(lactic acid) (PLA) is a well-known biodegradable polymer with strong potential application in food packaging industry. In this paper, samples of PLA clamshell for tomatoes packaging were exposed with 60CO γ-ray's source (1.33 MeV) at different dose levels (0, 10, 60, 150, 300, and 600 kGy), at room temperature and in presence of air. The physicochemical properties of neat PLA and sample exposed to gamma irradiation were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile measurements. Results show as the dose increases, the molecular weight (Mw), melting temperature (Tm), tensile strength and elongation at break decreased. However, the tensile modulus increased with increasing doses. The surface of PLA clamshells was degraded (scratches and minor cracks) when samples were exposed to doses greater than 60 kGy.

DOSE: an R/Bioconductor package for disease ontology semantic and enrichment analysis.

PubMed

Yu, Guangchuang; Wang, Li-Gen; Yan, Guang-Rong; He, Qing-Yu

2015-02-15

Disease ontology (DO) annotates human genes in the context of disease. DO is important annotation in translating molecular findings from high-throughput data to clinical relevance. DOSE is an R package providing semantic similarity computations among DO terms and genes which allows biologists to explore the similarities of diseases and of gene functions in disease perspective. Enrichment analyses including hypergeometric model and gene set enrichment analysis are also implemented to support discovering disease associations of high-throughput biological data. This allows biologists to verify disease relevance in a biological experiment and identify unexpected disease associations. Comparison among gene clusters is also supported. DOSE is released under Artistic-2.0 License. The source code and documents are freely available through Bioconductor (http://www.bioconductor.org/packages/release/bioc/html/DOSE.html). Supplementary data are available at Bioinformatics online. gcyu@connect.hku.hk or tqyhe@jnu.edu.cn. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Effect of low-dose (1 kGy) gamma radiation and selected phosphates on the microflora of vacuum-packaged ground pork

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ehioba, R.M.

1987-01-01

The effects of low-dose (1 kGy) gamma radiation and selected phosphates on the microbiology of refrigerated, vacuum-packaged ground pork were studied. Low-dose gamma radiation reduced the numbers of naturally occurring mesophiles, psychrotrophs, and anaerobes. The effect of low-dose radiation on the populations of lactic acid bacteria was minimal. On storage of the irradiated vacuum-packaged ground pork at 5/sup 0/C, there was a partial bacterial recovery, suggesting sublethal bacterial injury due to irradiation. When 10/sup 7/ CFU/g of meat is taken to be the level beyond which the meat would be considered spoiled, uninoculated, vacuum-packaged ground pork treated with 1 kGymore » (100 krad) of gamma radiation had 3.5 more days of shelf-life in terms of psychrotrophic total counts. In relation to anaerobic bacterial numbers, meat shelf-life was extended 2.5 days, while the shelf-life of meat was extended 1 day in terms of aerobic mesophilic bacteria. Irradiation prolonged shelf-life in inoculated (10/sup 5/CFU/g) meat for 1.0-1.5 days. Addition of 0.4% sodium acid pyrophosphate (SAPP) contributed 2 additional days to inoculated, irradiated vacuum-packaged ground pork shelf-life. However, SAPP had no added effect on naturally occurring microflora. Irradiation greatly decreased the numbers of gram-negative microorganisms, resulting in predominance of the gram-positive, nonsporeforming Lactobacillus and coryneform bacteria.« less

Using SAFRAN Software to Assess Radiological Hazards from Dismantling of Tammuz-2 Reactor Core at Al-tuwaitha Nuclear Site

NASA Astrophysics Data System (ADS)

Abed Gatea, Mezher; Ahmed, Anwar A.; jundee kadhum, Saad; Ali, Hasan Mohammed; Hussein Muheisn, Abbas

2018-05-01

The Safety Assessment Framework (SAFRAN) software has implemented here for radiological safety analysis; to verify that the dose acceptance criteria and safety goals are met with a high degree of confidence for dismantling of Tammuz-2 reactor core at Al-tuwaitha nuclear site. The activities characterizing, dismantling and packaging were practiced to manage the generated radioactive waste. Dose to the worker was considered an endpoint-scenario while dose to the public has neglected due to that Tammuz-2 facility is located in a restricted zone and 30m berm surrounded Al-tuwaitha site. Safety assessment for dismantling worker endpoint-scenario based on maximum external dose at component position level in the reactor pool and internal dose via airborne activity while, for characterizing and packaging worker endpoints scenarios have been done via external dose only because no evidence for airborne radioactivity hazards outside the reactor pool. The in-situ measurements approved that reactor core components are radiologically activated by Co-60 radioisotope. SAFRAN results showed that the maximum received dose for workers are (1.85, 0.64 and 1.3mSv/y) for activities dismantling, characterizing and packaging of reactor core components respectively. Hence, the radiological hazards remain below the low level hazard and within the acceptable annual dose for workers in radiation field

SU-E-T-368: Evaluating Dosimetric Outcome of Modulated Photon Radiotherapy (XMRT) Optimization for Head and Neck Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGeachy, P; Villarreal-Barajas, JE; Khan, R

2015-06-15

Purpose: The dosimetric outcome of optimized treatment plans obtained by modulating the photon beamlet energy and fluence on a small cohort of four Head and Neck (H and N) patients was investigated. This novel optimization technique is denoted XMRT for modulated photon radiotherapy. The dosimetric plans from XMRT for H and N treatment were compared to conventional, 6 MV intensity modulated radiotherapy (IMRT) optimization plans. Methods: An arrangement of two non-coplanar and five coplanar beams was used for all four H and N patients. Both XMRT and IMRT were subject to the same optimization algorithm, with XMRT optimization allowing bothmore » 6 and 18 MV beamlets while IMRT was restricted to 6 MV only. The optimization algorithm was based on a linear programming approach with partial-volume constraints implemented via the conditional value-at-risk method. H and N constraints were based off of those mentioned in the Radiation Therapy Oncology Group 1016 protocol. XMRT and IMRT solutions were assessed using metrics suggested by International Commission on Radiation Units and Measurements report 83. The Gurobi solver was used in conjunction with the CVX package to solve each optimization problem. Dose calculations and analysis were done in CERR using Monte Carlo dose calculation with VMC{sub ++}. Results: Both XMRT and IMRT solutions met all clinical criteria. Trade-offs were observed between improved dose uniformity to the primary target volume (PTV1) and increased dose to some of the surrounding healthy organs for XMRT compared to IMRT. On average, IMRT improved dose to the contralateral parotid gland and spinal cord while XMRT improved dose to the brainstem and mandible. Conclusion: Bi-energy XMRT optimization for H and N patients provides benefits in terms of improved dose uniformity to the primary target and reduced dose to some healthy structures, at the expense of increased dose to other healthy structures when compared with IMRT.« less

Package Design Affects Accuracy Recognition for Medications.

PubMed

Endestad, Tor; Wortinger, Laura A; Madsen, Steinar; Hortemo, Sigurd

2016-12-01

Our aim was to test if highlighting and placement of substance name on medication package have the potential to reduce patient errors. An unintentional overdose of medication is a large health issue that might be linked to medication package design. In two experiments, placement, background color, and the active ingredient of generic medication packages were manipulated according to best human factors guidelines to reduce causes of labeling-related patient errors. In two experiments, we compared the original packaging with packages where we varied placement of the name, dose, and background of the active ingredient. Age-relevant differences and the effect of color on medication recognition error were tested. In Experiment 1, 59 volunteers (30 elderly and 29 young students), participated. In Experiment 2, 25 volunteers participated. The most common error was the inability to identify that two different packages contained the same active ingredient (young, 41%, and elderly, 68%). This kind of error decreased with the redesigned packages (young, 8%, and elderly, 16%). Confusion errors related to color design were reduced by two thirds in the redesigned packages compared with original generic medications. Prominent placement of substance name and dose with a band of high-contrast color support recognition of the active substance in medications. A simple modification including highlighting and placing the name of the active ingredient in the upper right-hand corner of the package helps users realize that two different packages can contain the same active substance, thus reducing the risk of inadvertent medication overdose. © 2016, Human Factors and Ergonomics Society.

Package Design Affects Accuracy Recognition for Medications

PubMed Central

Endestad, Tor; Wortinger, Laura A.; Madsen, Steinar; Hortemo, Sigurd

2016-01-01

Objective: Our aim was to test if highlighting and placement of substance name on medication package have the potential to reduce patient errors. Background: An unintentional overdose of medication is a large health issue that might be linked to medication package design. In two experiments, placement, background color, and the active ingredient of generic medication packages were manipulated according to best human factors guidelines to reduce causes of labeling-related patient errors. Method: In two experiments, we compared the original packaging with packages where we varied placement of the name, dose, and background of the active ingredient. Age-relevant differences and the effect of color on medication recognition error were tested. In Experiment 1, 59 volunteers (30 elderly and 29 young students), participated. In Experiment 2, 25 volunteers participated. Results: The most common error was the inability to identify that two different packages contained the same active ingredient (young, 41%, and elderly, 68%). This kind of error decreased with the redesigned packages (young, 8%, and elderly, 16%). Confusion errors related to color design were reduced by two thirds in the redesigned packages compared with original generic medications. Conclusion: Prominent placement of substance name and dose with a band of high-contrast color support recognition of the active substance in medications. Application: A simple modification including highlighting and placing the name of the active ingredient in the upper right-hand corner of the package helps users realize that two different packages can contain the same active substance, thus reducing the risk of inadvertent medication overdose. PMID:27591209

Recent developments and comprehensive evaluations of a GPU-based Monte Carlo package for proton therapy

PubMed Central

Qin, Nan; Botas, Pablo; Giantsoudi, Drosoula; Schuemann, Jan; Tian, Zhen; Jiang, Steve B.; Paganetti, Harald; Jia, Xun

2016-01-01

Monte Carlo (MC) simulation is commonly considered as the most accurate dose calculation method for proton therapy. Aiming at achieving fast MC dose calculations for clinical applications, we have previously developed a GPU-based MC tool, gPMC. In this paper, we report our recent updates on gPMC in terms of its accuracy, portability, and functionality, as well as comprehensive tests on this tool. The new version, gPMC v2.0, was developed under the OpenCL environment to enable portability across different computational platforms. Physics models of nuclear interactions were refined to improve calculation accuracy. Scoring functions of gPMC were expanded to enable tallying particle fluence, dose deposited by different particle types, and dose-averaged linear energy transfer (LETd). A multiple counter approach was employed to improve efficiency by reducing frequency of memory writing conflict at scoring. For dose calculation, accuracy improvements over gPMC v1.0 were observed in both water phantom cases and a patient case. For a prostate cancer case planned using high-energy proton beams, dose discrepancies in beam entrance and target region seen in gPMC v1.0 with respect to the gold standard tool for proton Monte Carlo simulations (TOPAS) results were substantially reduced and gamma test passing rate (1%/1mm) was improved from 82.7% to 93.1%. Average relative difference in LETd between gPMC and TOPAS was 1.7%. Average relative differences in dose deposited by primary, secondary, and other heavier particles were within 2.3%, 0.4%, and 0.2%. Depending on source proton energy and phantom complexity, it took 8 to 17 seconds on an AMD Radeon R9 290x GPU to simulate 107 source protons, achieving less than 1% average statistical uncertainty. As beam size was reduced from 10×10 cm2 to 1×1 cm2, time on scoring was only increased by 4.8% with eight counters, in contrast to a 40% increase using only one counter. With the OpenCL environment, the portability of gPMC v2.0 was enhanced. It was successfully executed on different CPUs and GPUs and its performance on different devices varied depending on processing power and hardware structure. PMID:27694712

SU-C-204-06: Monte Carlo Dose Calculation for Kilovoltage X-Ray-Psoralen Activated Cancer Therapy (X-PACT): Preliminary Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mein, S; Gunasingha, R; Nolan, M

Purpose: X-PACT is an experimental cancer therapy where kV x-rays are used to photo-activate anti-cancer therapeutics through phosphor intermediaries (phosphors that absorb x-rays and re-radiate as UV light). Clinical trials in pet dogs are currently underway (NC State College of Veterinary Medicine) and an essential component is the ability to model the kV dose in these dogs. Here we report the commissioning and characterization of a Monte Carlo (MC) treatment planning simulation tool to calculate X-PACT radiation doses in canine trials. Methods: FLUKA multi-particle MC simulation package was used to simulate a standard X-PACT radiation treatment beam of 80kVp withmore » the Varian OBI x-ray source geometry. The beam quality was verified by comparing measured and simulated attenuation of the beam by various thicknesses of aluminum (2–4.6 mm) under narrow beam conditions (HVL). The beam parameters at commissioning were then corroborated using MC, characterized and verified with empirically collected commissioning data, including: percent depth dose curves (PDD), back-scatter factors (BSF), collimator scatter factor(s), and heel effect, etc. All simulations were conducted for N=30M histories at M=100 iterations. Results: HVL and PDD simulation data agreed with an average percent error of 2.42%±0.33 and 6.03%±1.58, respectively. The mean square error (MSE) values for HVL and PDD (0.07% and 0.50%) were low, as expected; however, longer simulations are required to validate convergence to the expected values. Qualitatively, pre- and post-filtration source spectra matched well with 80kVp references generated via SPEKTR software. Further validation of commissioning data simulation is underway in preparation for first-time 3D dose calculations with canine CBCT data. Conclusion: We have prepared a Monte Carlo simulation capable of accurate dose calculation for use with ongoing X-PACT canine clinical trials. Preliminary results show good agreement with measured data and hold promise for accurate quantification of dose for this novel psoralen X-ray therapy. Funding Support, Disclosures, & Conflict of Interest: The Monte Carlo simulation work was not funded; Drs. Adamson & Oldham have received funding from Immunolight LLC for X-PACT research.« less

Long duration exposure facility solar illumination data package

NASA Technical Reports Server (NTRS)

Berrios, William M.; Sampair, Thomas

1990-01-01

A post flight solar illumination data package was created by the LDEF thermal analysis data group in support of the LDEF science office data group. The data presented was prepared with the Thermal Radiation Analysis System (TRASYS) program. Ground tracking data was used to calculate daily orbital beta angles for the calculation of resultant fluxes. This data package will be useful in calculation of solar illumination fluent for a variety of beta angle orbital conditions encountered during the LDEF mission.

Decontamination of food packaging using electron beam—status and prospects

NASA Astrophysics Data System (ADS)

Mittendorfer, J.; Bierbaumer, H. P.; Gratzl, F.; Kellauer, E.

2002-03-01

In this paper the status of food packaging disinfection decontamination using electron beam at Mediscan GmbH is presented. The first section of the paper describes the activities at the service center, where food packaging materials, e.g. yoghurt cups are decontaminated in their final shipment containers. As important step in the hazard analysis and critical control point of food processing, microbiological uncontaminated food packaging material is of public interest and attracts a lot of attention from packaging material producers and food processors. The dose ranges for different sterility assurance levels are discussed and results from microbiological test are presented. Studies at Mediscan have demonstrated, that an electron beam treatment at a dose of 5-7 kGy is most effective against yeast and mold, which are mainly responsible for spoilage and short shelf-life of a variety of products. The second section is devoted to the field of inline decontamination of food packaging and sterilization of pharmaceutical packaging material and the research currently conducted at Mediscan. The requirements for industrial inline electron beam systems are summarized and design concepts discussed in terms of beam energy, beam current, irradiation topology, product handling and shielding.

EPA and EFSA approaches for Benchmark Dose modeling

EPA Science Inventory

Benchmark dose (BMD) modeling has become the preferred approach in the analysis of toxicological dose-response data for the purpose of deriving human health toxicity values. The software packages most often used are Benchmark Dose Software (BMDS, developed by EPA) and PROAST (de...

SU-F-J-146: Experimental Validation of 6 MV Photon PDD in Parallel Magnetic Field Calculated by EGSnrc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghila, A; Steciw, S; Fallone, B

Purpose: Integrated linac-MR systems are uniquely suited for real time tumor tracking during radiation treatment. Understanding the magnetic field dose effects and incorporating them in treatment planning is paramount for linac-MR clinical implementation. We experimentally validated the EGSnrc dose calculations in the presence of a magnetic field parallel to the radiation beam travel. Methods: Two cylindrical bore electromagnets produced a 0.21 T magnetic field parallel to the central axis of a 6 MV photon beam. A parallel plate ion chamber was used to measure the PDD in a polystyrene phantom, placed inside the bore in two setups: phantom top surfacemore » coinciding with the magnet bore center (183 cm SSD), and with the magnet bore’s top surface (170 cm SSD). We measured the field of the magnet at several points and included the exact dimensions of the coils to generate a 3D magnetic field map in a finite element model. BEAMnrc and DOSXYZnrc simulated the PDD experiments in parallel magnetic field (i.e. 3D magnetic field included) and with no magnetic field. Results: With the phantom surface at the top of the electromagnet, the surface dose increased by 10% (compared to no-magnetic field), due to electrons being focused by the smaller fringe fields of the electromagnet. With the phantom surface at the bore center, the surface dose increased by 30% since extra 13 cm of air column was in relatively higher magnetic field (>0.13T) in the magnet bore. EGSnrc Monte Carlo code correctly calculated the radiation dose with and without the magnetic field, and all points passed the 2%, 2 mm Gamma criterion when the ion chamber’s entrance window and air cavity were included in the simulated phantom. Conclusion: A parallel magnetic field increases the surface and buildup dose during irradiation. The EGSnrc package can model these magnetic field dose effects accurately. Dr. Fallone is a co-founder and CEO of MagnetTx Oncology Solutions (under discussions to license Alberta bi-planar linac MR for commercialization).« less

VirtualDose: a software for reporting organ doses from CT for adult and pediatric patients.

PubMed

Ding, Aiping; Gao, Yiming; Liu, Haikuan; Caracappa, Peter F; Long, Daniel J; Bolch, Wesley E; Liu, Bob; Xu, X George

2015-07-21

This paper describes the development and testing of VirtualDose--a software for reporting organ doses for adult and pediatric patients who undergo x-ray computed tomography (CT) examinations. The software is based on a comprehensive database of organ doses derived from Monte Carlo (MC) simulations involving a library of 25 anatomically realistic phantoms that represent patients of different ages, body sizes, body masses, and pregnant stages. Models of GE Lightspeed Pro 16 and Siemens SOMATOM Sensation 16 scanners were carefully validated for use in MC dose calculations. The software framework is designed with the 'software as a service (SaaS)' delivery concept under which multiple clients can access the web-based interface simultaneously from any computer without having to install software locally. The RESTful web service API also allows a third-party picture archiving and communication system software package to seamlessly integrate with VirtualDose's functions. Software testing showed that VirtualDose was compatible with numerous operating systems including Windows, Linux, Apple OS X, and mobile and portable devices. The organ doses from VirtualDose were compared against those reported by CT-Expo and ImPACT-two dosimetry tools that were based on the stylized pediatric and adult patient models that were known to be anatomically simple. The organ doses reported by VirtualDose differed from those reported by CT-Expo and ImPACT by as much as 300% in some of the patient models. These results confirm the conclusion from past studies that differences in anatomical realism offered by stylized and voxel phantoms have caused significant discrepancies in CT dose estimations.

Training software using virtual-reality technology and pre-calculated effective dose data.

PubMed

Ding, Aiping; Zhang, Di; Xu, X George

2009-05-01

This paper describes the development of a software package, called VR Dose Simulator, which aims to provide interactive radiation safety and ALARA training to radiation workers using virtual-reality (VR) simulations. Combined with a pre-calculated effective dose equivalent (EDE) database, a virtual radiation environment was constructed in VR authoring software, EON Studio, using 3-D models of a real nuclear power plant building. Models of avatars representing two workers were adopted with arms and legs of the avatar being controlled in the software to simulate walking and other postures. Collision detection algorithms were developed for various parts of the 3-D power plant building and avatars to confine the avatars to certain regions of the virtual environment. Ten different camera viewpoints were assigned to conveniently cover the entire virtual scenery in different viewing angles. A user can control the avatar to carry out radiological engineering tasks using two modes of avatar navigation. A user can also specify two types of radiation source: Cs and Co. The location of the avatar inside the virtual environment during the course of the avatar's movement is linked to the EDE database. The accumulative dose is calculated and displayed on the screen in real-time. Based on the final accumulated dose and the completion status of all virtual tasks, a score is given to evaluate the performance of the user. The paper concludes that VR-based simulation technologies are interactive and engaging, thus potentially useful in improving the quality of radiation safety training. The paper also summarizes several challenges: more streamlined data conversion, realistic avatar movement and posture, more intuitive implementation of the data communication between EON Studio and VB.NET, and more versatile utilization of EDE data such as a source near the body, etc., all of which needs to be addressed in future efforts to develop this type of software.

Modelling of an Orthovoltage X-ray Therapy Unit with the EGSnrc Monte Carlo Package

NASA Astrophysics Data System (ADS)

Knöös, Tommy; Rosenschöld, Per Munck Af; Wieslander, Elinore

2007-06-01

Simulations with the EGSnrc code package of an orthovoltage x-ray machine have been performed. The BEAMnrc code was used to transport electrons, produce x-ray photons in the target and transport of these through the treatment machine down to the exit level of the applicator. Further transport in water or CT based phantoms was facilitated by the DOSXYZnrc code. Phase space files were scored with BEAMnrc and analysed regarding the energy spectra at the end of the applicator. Tuning of simulation parameters was based on the half-value layer quantity for the beams in either Al or Cu. Calculated depth dose and profile curves have been compared against measurements and show good agreement except at shallow depths. The MC model tested in this study can be used for various dosimetric studies as well as generating a library of typical treatment cases that can serve as both educational material and guidance in the clinical practice

Analysis of Plane-Parallel Electron Beam Propagation in Different Media by Numerical Simulation Methods

NASA Astrophysics Data System (ADS)

Miloichikova, I. A.; Bespalov, V. I.; Krasnykh, A. A.; Stuchebrov, S. G.; Cherepennikov, Yu. M.; Dusaev, R. R.

2018-04-01

Simulation by the Monte Carlo method is widely used to calculate the character of ionizing radiation interaction with substance. A wide variety of programs based on the given method allows users to choose the most suitable package for solving computational problems. In turn, it is important to know exactly restrictions of numerical systems to avoid gross errors. Results of estimation of the feasibility of application of the program PCLab (Computer Laboratory, version 9.9) for numerical simulation of the electron energy distribution absorbed in beryllium, aluminum, gold, and water for industrial, research, and clinical beams are presented. The data obtained using programs ITS and Geant4 being the most popular software packages for solving the given problems and the program PCLab are presented in the graphic form. A comparison and an analysis of the results obtained demonstrate the feasibility of application of the program PCLab for simulation of the absorbed energy distribution and dose of electrons in various materials for energies in the range 1-20 MeV.

MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model -Documentation of the Hydrogeologic-Unit Flow (HUF) Package

USGS Publications Warehouse

Anderman, E.R.; Hill, M.C.

2000-01-01

This report documents the Hydrogeologic-Unit Flow (HUF) Package for the groundwater modeling computer program MODFLOW-2000. The HUF Package is an alternative internal flow package that allows the vertical geometry of the system hydrogeology to be defined explicitly within the model using hydrogeologic units that can be different than the definition of the model layers. The HUF Package works with all the processes of MODFLOW-2000. For the Ground-Water Flow Process, the HUF Package calculates effective hydraulic properties for the model layers based on the hydraulic properties of the hydrogeologic units, which are defined by the user using parameters. The hydraulic properties are used to calculate the conductance coefficients and other terms needed to solve the ground-water flow equation. The sensitivity of the model to the parameters defined within the HUF Package input file can be calculated using the Sensitivity Process, using observations defined with the Observation Process. Optimal values of the parameters can be estimated by using the Parameter-Estimation Process. The HUF Package is nearly identical to the Layer-Property Flow (LPF) Package, the major difference being the definition of the vertical geometry of the system hydrogeology. Use of the HUF Package is illustrated in two test cases, which also serve to verify the performance of the package by showing that the Parameter-Estimation Process produces the true parameter values when exact observations are used.

Calculation of the Naval Long and Short Waste Package Three-Dimensional Thermal Interface Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

H. Marr

2006-10-25

The purpose of this calculation is to evaluate the thermal performance of the Naval Long and Naval Short spent nuclear fuel (SNF) waste packages (WP) in the repository emplacement drift. The scope of this calculation is limited to the determination of the temperature profiles upon the surfaces of the Naval Long and Short SNF waste package for up to 10,000 years of emplacement. The temperatures on the top of the outside surface of the naval canister are the thermal interfaces for the Naval Nuclear Propulsion Program (NNPP). The results of this calculation are intended to support Licensing Application design activities.

Effect of ionizing radiation on physicochemical and mechanical properties of commercial multilayer coextruded flexible plastics packaging materials

NASA Astrophysics Data System (ADS)

Goulas, Antonios E.; Riganakos, Kyriakos A.; Kontominas, Michael G.

2003-12-01

The effect of gamma radiation (doses: 5, 10 and 30 kGy) on mechanical properties, gas and water vapour permeability and overall migration values into distilled water, 3% aqueous acetic acid and iso-octane was studied for a series of commercial multilayer flexible packaging materials based on coextruded polypropylene (PP), ethylene vinyl alcohol (EVOH), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polyamide (PA) and Ionomer. The results showed that radiation doses of 5 and 10 kGy induced no statistically significant differences ( p>0.05) in all polymer properties examined. A dose of 30 kGy induced differences ( p<0.05) in the mechanical properties of PA/LDPE, LDPE/EVOH/LDPE and LDPE/PA/Ionomer films. In addition, the same dose induced differences ( p<0.05) in the overall migration from Ionomer/EVOH/LDPE and LDPE/PA/Ionomer films into 3% acetic acid and iso-octane and in the overall migration from PP/EVOH/LDPE-LLDPE into iso-octane. Differences recorded, are discussed in relation to food irradiation applications of respective packaging materials.

Perfusion CT of the Brain and Liver and of Lung Tumors: Use of Monte Carlo Simulation for Patient Dose Estimation for Examinations With a Cone-Beam 320-MDCT Scanner.

PubMed

Cros, Maria; Geleijns, Jacob; Joemai, Raoul M S; Salvadó, Marçal

2016-01-01

The purpose of this study was to estimate the patient dose from perfusion CT examinations of the brain, lung tumors, and the liver on a cone-beam 320-MDCT scanner using a Monte Carlo simulation and the recommendations of the International Commission on Radiological Protection (ICRP). A Monte Carlo simulation based on the Electron Gamma Shower Version 4 package code was used to calculate organ doses and the effective dose in the reference computational phantoms for an adult man and adult woman as published by the ICRP. Three perfusion CT acquisition protocols--brain, lung tumor, and liver perfusion--were evaluated. Additionally, dose assessments were performed for the skin and for the eye lens. Conversion factors were obtained to estimate effective doses and organ doses from the volume CT dose index and dose-length product. The sex-averaged effective doses were approximately 4 mSv for perfusion CT of the brain and were between 23 and 26 mSv for the perfusion CT body protocols. The eye lens dose from the brain perfusion CT examination was approximately 153 mGy. The sex-averaged peak entrance skin dose (ESD) was 255 mGy for the brain perfusion CT studies, 157 mGy for the lung tumor perfusion CT studies, and 172 mGy for the liver perfusion CT studies. The perfusion CT protocols for imaging the brain, lung tumors, and the liver performed on a 320-MDCT scanner yielded patient doses that are safely below the threshold doses for deterministic effects. The eye lens dose, peak ESD, and effective doses can be estimated for other clinical perfusion CT examinations from the conversion factors that were derived in this study.

An Algorithm and R Program for Fitting and Simulation of Pharmacokinetic and Pharmacodynamic Data.

PubMed

Li, Jijie; Yan, Kewei; Hou, Lisha; Du, Xudong; Zhu, Ping; Zheng, Li; Zhu, Cairong

2017-06-01

Pharmacokinetic/pharmacodynamic link models are widely used in dose-finding studies. By applying such models, the results of initial pharmacokinetic/pharmacodynamic studies can be used to predict the potential therapeutic dose range. This knowledge can improve the design of later comparative large-scale clinical trials by reducing the number of participants and saving time and resources. However, the modeling process can be challenging, time consuming, and costly, even when using cutting-edge, powerful pharmacological software. Here, we provide a freely available R program for expediently analyzing pharmacokinetic/pharmacodynamic data, including data importation, parameter estimation, simulation, and model diagnostics. First, we explain the theory related to the establishment of the pharmacokinetic/pharmacodynamic link model. Subsequently, we present the algorithms used for parameter estimation and potential therapeutic dose computation. The implementation of the R program is illustrated by a clinical example. The software package is then validated by comparing the model parameters and the goodness-of-fit statistics generated by our R package with those generated by the widely used pharmacological software WinNonlin. The pharmacokinetic and pharmacodynamic parameters as well as the potential recommended therapeutic dose can be acquired with the R package. The validation process shows that the parameters estimated using our package are satisfactory. The R program developed and presented here provides pharmacokinetic researchers with a simple and easy-to-access tool for pharmacokinetic/pharmacodynamic analysis on personal computers.

Monte Carlo simulation of electron beams from an accelerator head using PENELOPE.

PubMed

Sempau, J; Sánchez-Reyes, A; Salvat, F; ben Tahar, H O; Jiang, S B; Fernández-Varea, J M

2001-04-01

The Monte Carlo code PENELOPE has been used to simulate electron beams from a Siemens Mevatron KDS linac with nominal energies of 6, 12 and 18 MeV. Owing to its accuracy, which stems from that of the underlying physical interaction models, PENELOPE is suitable for simulating problems of interest to the medical physics community. It includes a geometry package that allows the definition of complex quadric geometries, such as those of irradiation instruments, in a straightforward manner. Dose distributions in water simulated with PENELOPE agree well with experimental measurements using a silicon detector and a monitoring ionization chamber. Insertion of a lead slab in the incident beam at the surface of the water phantom produces sharp variations in the dose distributions, which are correctly reproduced by the simulation code. Results from PENELOPE are also compared with those of equivalent simulations with the EGS4-based user codes BEAM and DOSXYZ. Angular and energy distributions of electrons and photons in the phase-space plane (at the downstream end of the applicator) obtained from both simulation codes are similar, although significant differences do appear in some cases. These differences, however, are shown to have a negligible effect on the calculated dose distributions. Various practical aspects of the simulations, such as the calculation of statistical uncertainties and the effect of the 'latent' variance in the phase-space file, are discussed in detail.

21 CFR 310.518 - Drug products containing iron or iron salts.

Code of Federal Regulations, 2011 CFR

2011-04-01

... an active ingredient in solid oral dosage form, e.g., tablets or capsules shall meet the following.... (ii) If a drug product is packaged in unit-dose packaging, and if the immediate container bears...

21 CFR 310.518 - Drug products containing iron or iron salts.

Code of Federal Regulations, 2010 CFR

2010-04-01

... an active ingredient in solid oral dosage form, e.g., tablets or capsules shall meet the following.... (ii) If a drug product is packaged in unit-dose packaging, and if the immediate container bears...

Strengths and Weaknesses of a Planar Whole-Body Method of 153Sm Dosimetry for Patients with Metastatic Osteosarcoma and Comparison with Three-Dimensional Dosimetry

PubMed Central

Plyku, Donika; Loeb, David M.; Prideaux, Andrew R.; Baechler, Sébastien; Wahl, Richard L.; Sgouros, George

2015-01-01

Abstract Purpose: Dosimetric accuracy depends directly upon the accuracy of the activity measurements in tumors and organs. The authors present the methods and results of a retrospective tumor dosimetry analysis in 14 patients with a total of 28 tumors treated with high activities of 153Sm-ethylenediaminetetramethylenephosphonate (153Sm-EDTMP) for therapy of metastatic osteosarcoma using planar images and compare the results with three-dimensional dosimetry. Materials and Methods: Analysis of phantom data provided a complete set of parameters for dosimetric calculations, including buildup factor, attenuation coefficient, and camera dead-time compensation. The latter was obtained using a previously developed methodology that accounts for the relative motion of the camera and patient during whole-body (WB) imaging. Tumor activity values calculated from the anterior and posterior views of WB planar images of patients treated with 153Sm-EDTMP for pediatric osteosarcoma were compared with the geometric mean value. The mean activities were integrated over time and tumor-absorbed doses were calculated using the software package OLINDA/EXM. Results: The authors found that it was necessary to employ the dead-time correction algorithm to prevent measured tumor activity half-lives from often exceeding the physical decay half-life of 153Sm. Measured half-lives so long are unquestionably in error. Tumor-absorbed doses varied between 0.0022 and 0.27 cGy/MBq with an average of 0.065 cGy/MBq; however, a comparison with absorbed dose values derived from a three-dimensional analysis for the same tumors showed no correlation; moreover, the ratio of three-dimensional absorbed dose value to planar absorbed dose value was 2.19. From the anterior and posterior activity comparisons, the order of clinical uncertainty for activity and dose calculations from WB planar images, with the present methodology, is hypothesized to be about 70%. Conclusion: The dosimetric results from clinical patient data indicate that absolute planar dosimetry is unreliable and dosimetry using three-dimensional imaging is preferable, particularly for tumors, except perhaps for the most sophisticated planar methods. The relative activity and patient kinetics derived from planar imaging show a greater level of reliability than the dosimetry. PMID:26560193

Development and validation of an improved method for the determination of chloropropanols in paperboard food packaging by GC-MS.

PubMed

Mezouari, S; Liu, W Yun; Pace, G; Hartman, T G

2015-01-01

The objective of this study was to develop an improved analytical method for the determination of 3-chloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in paper-type food packaging. The established method includes aqueous extraction, matrix spiking of a deuterated surrogate internal standard (3-MCPD-d₅), clean-up using Extrelut solid-phase extraction, derivatisation using a silylation reagent, and GC-MS analysis of the chloropropanols as their corresponding trimethyl silyl ethers. The new method is applicable to food-grade packaging samples using European Commission standard aqueous extraction and aqueous food stimulant migration tests. In this improved method, the derivatisation procedure was optimised; the cost and time of the analysis were reduced by using 10 times less sample, solvents and reagents than in previously described methods. Overall the validation data demonstrate that the method is precise and reliable. The limit of detection (LOD) of the aqueous extract was 0.010 mg kg(-1) (w/w) for both 3-MCPD and 1,3-DCP. Analytical precision had a relative standard deviation (RSD) of 3.36% for 3-MCPD and an RSD of 7.65% for 1,3-DCP. The new method was satisfactorily applied to the analysis of over 100 commercial paperboard packaging samples. The data are being used to guide the product development of a next generation of wet-strength resins with reduced chloropropanol content, and also for risk assessments to calculate the virtual safe dose (VSD).

Identification of irradiated strawberries (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deschreider, A.R.; Vigneron, J.M.

1973-01-01

From international colloquium: the identification of irradiated foodstuffs; Karlsruhe, Germany (24 0ct 1973). Packaged strawberries were irradiated with doses of 100, 200, and 500 krad of /sup 60/Co gamma rays. The irradiation of the fruit at these levels could not be detected either by measuring of the coloration of the anthocyanin extraction or the radioactivity of the phenylalanine-ammonia-lyase. If there is any plastic in the packaging material, examination under close infrared light reveals spectral modification when the dose level reaches 200 krad. (GE)

A Tutorial on RxODE: Simulating Differential Equation Pharmacometric Models in R.

PubMed

Wang, W; Hallow, K M; James, D A

2016-01-01

This tutorial presents the application of an R package, RxODE, that facilitates quick, efficient simulations of ordinary differential equation models completely within R. Its application is illustrated through simulation of design decision effects on an adaptive dosing regimen. The package provides an efficient, versatile way to specify dosing scenarios and to perform simulation with variability with minimal custom coding. Models can be directly translated to Rshiny applications to facilitate interactive, real-time evaluation/iteration on simulation scenarios.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morley, Steven

The PyForecastTools package provides Python routines for calculating metrics for model validation, forecast verification and model comparison. For continuous predictands the package provides functions for calculating bias (mean error, mean percentage error, median log accuracy, symmetric signed bias), and for calculating accuracy (mean squared error, mean absolute error, mean absolute scaled error, normalized RMSE, median symmetric accuracy). Convenience routines to calculate the component parts (e.g. forecast error, scaled error) of each metric are also provided. To compare models the package provides: generic skill score; percent better. Robust measures of scale including median absolute deviation, robust standard deviation, robust coefficient ofmore » variation and the Sn estimator are all provided by the package. Finally, the package implements Python classes for NxN contingency tables. In the case of a multi-class prediction, accuracy and skill metrics such as proportion correct and the Heidke and Peirce skill scores are provided as object methods. The special case of a 2x2 contingency table inherits from the NxN class and provides many additional metrics for binary classification: probability of detection, probability of false detection, false alarm ration, threat score, equitable threat score, bias. Confidence intervals for many of these quantities can be calculated using either the Wald method or Agresti-Coull intervals.« less

SU-C-201-06: Utility of Quantitative 3D SPECT/CT Imaging in Patient Specific Internal Dosimetry of 153-Samarium with GATE Monte Carlo Package

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fallahpoor, M; Abbasi, M; Sen, A

Purpose: Patient-specific 3-dimensional (3D) internal dosimetry in targeted radionuclide therapy is essential for efficient treatment. Two major steps to achieve reliable results are: 1) generating quantitative 3D images of radionuclide distribution and attenuation coefficients and 2) using a reliable method for dose calculation based on activity and attenuation map. In this research, internal dosimetry for 153-Samarium (153-Sm) was done by SPECT-CT images coupled GATE Monte Carlo package for internal dosimetry. Methods: A 50 years old woman with bone metastases from breast cancer was prescribed 153-Sm treatment (Gamma: 103keV and beta: 0.81MeV). A SPECT/CT scan was performed with the Siemens Simbia-Tmore » scanner. SPECT and CT images were registered using default registration software. SPECT quantification was achieved by compensating for all image degrading factors including body attenuation, Compton scattering and collimator-detector response (CDR). Triple energy window method was used to estimate and eliminate the scattered photons. Iterative ordered-subsets expectation maximization (OSEM) with correction for attenuation and distance-dependent CDR was used for image reconstruction. Bilinear energy mapping is used to convert Hounsfield units in CT image to attenuation map. Organ borders were defined by the itk-SNAP toolkit segmentation on CT image. GATE was then used for internal dose calculation. The Specific Absorbed Fractions (SAFs) and S-values were reported as MIRD schema. Results: The results showed that the largest SAFs and S-values are in osseous organs as expected. S-value for lung is the highest after spine that can be important in 153-Sm therapy. Conclusion: We presented the utility of SPECT-CT images and Monte Carlo for patient-specific dosimetry as a reliable and accurate method. It has several advantages over template-based methods or simplified dose estimation methods. With advent of high speed computers, Monte Carlo can be used for treatment planning on a day to day basis.« less

Empirical determination of collimator scatter data for use in Radcalc commercial monitor unit calculation software: Implication for prostate volumetric modulated-arc therapy calculations.

PubMed

Richmond, Neil; Tulip, Rachael; Walker, Chris

2016-01-01

The aim of this work was to determine, by measurement and independent monitor unit (MU) check, the optimum method for determining collimator scatter for an Elekta Synergy linac with an Agility multileaf collimator (MLC) within Radcalc, a commercial MU calculation software package. The collimator scatter factors were measured for 13 field shapes defined by an Elekta Agility MLC on a Synergy linac with 6MV photons. The value of the collimator scatter associated with each field was also calculated according to the equation Sc=Sc(mlc)+Sc(corr)(Sc(open)-Sc(mlc)) with Sc(corr) varied between 0 and 1, where Sc(open) is the value of collimator scatter calculated from the rectangular collimator-defined field and Sc(mlc) the value using only the MLC-defined field shape by applying sector integration. From this the optimum value of the correction was determined as that which gives the minimum difference between measured and calculated Sc. Single (simple fluence modulation) and dual-arc (complex fluence modulation) treatment plans were generated on the Monaco system for prostate volumetric modulated-arc therapy (VMAT) delivery. The planned MUs were verified by absolute dose measurement in phantom and by an independent MU calculation. The MU calculations were repeated with values of Sc(corr) between 0 and 1. The values of the correction yielding the minimum MU difference between treatment planning system (TPS) and check MU were established. The empirically derived value of Sc(corr) giving the best fit to the measured collimator scatter factors was 0.49. This figure however was not found to be optimal for either the single- or dual-arc prostate VMAT plans, which required 0.80 and 0.34, respectively, to minimize the differences between the TPS and independent-check MU. Point dose measurement of the VMAT plans demonstrated that the TPS MUs were appropriate for the delivered dose. Although the value of Sc(corr) may be obtained by direct comparison of calculation with measurement, the efficacy of the value determined for VMAT-MU calculations are very much dependent on the complexity of the MLC delivery. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Postharvest changes in the phenolic profile of watercress induced by post-packaging irradiation and modified atmosphere packaging.

PubMed

Pinela, José; Barros, Lillian; Barreira, João C M; Carvalho, Ana Maria; Oliveira, M Beatriz P P; Santos-Buelga, Celestino; Ferreira, Isabel C F R

2018-07-15

The effects of γ-ray irradiation and modified atmosphere packaging (MAP) on watercress (Nasturtium officinale R. Br.) phenolic compounds were evaluated after 7-day storage at 4 °C. Irradiation doses of 1, 2 and 5 kGy were tested, as well as vacuum-packaging and MAP enriched with 100% N 2 and Ar. A non-irradiated, air-packaged control was included in all experiments. p-Coumaric acid was the most abundant compound in fresh watercress, followed by quercetin-3-O-sophoroside and isorhamnetin-O-hydroxyferuloylhexoside-O-hexoside. Four kaempferol glycoside derivatives were identified for the first time in this species. In general, flavonoids predominated over phenolic acids. Samples stored under vacuum and irradiated at 2 kGy revealed lower phenolic levels. Ar-enriched MAP and control conditions preserved the initial phenolic content. The 5 kGy dose also maintained concentrations of flavonoids and total phenolic compounds, but increased the phenolic acids content. Additionally, flavonoids were found strongly correlated to DPPH scavenging activity and β-carotene bleaching inhibition capacity. Copyright © 2018 Elsevier Ltd. All rights reserved.

An Experimental Study of Diffusivity of Technetium-99 in Hanford Vadose Zone Sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattigod, Shas V.; Bovaird, Chase C.; Wellman, Dawn M.

2012-11-01

One of the methods being considered at the Hanford site in Washington for safely disposing of low-level radioactive wastes (LLW) is to encase the waste in concrete and entomb the packages in the Hanford vadose zone sediments. The current plan for waste isolation consists of stacking low-level waste packages on a trench floor, surrounding the stacks with reinforced steel, and encasing these packages with concrete. Any failure of the concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion andmore » move into the surrounding subsurface sediments. It is therefore necessary to conduct an assessment of the performance of the concrete encasement structure and the surrounding soil’s ability to retard radionuclide migration. The retardation factors for radionuclides contained in the waste packages can be determined from measurements of diffusion coefficients for these contaminants through concrete and fill material. Because of their anionic nature in aqueous solutions, the radionuclides, 99Tc and 129I were identified as long-term dose contributors in LLW. The leachability and/or diffusion of these radionuclide species must be measured in order to assess the long-term performance of waste grouts when contacted with vadose-zone porewater or groundwater. To measure the diffusivity, a set of experiments were conducted using 99Tc-spiked concrete (with 0 and 4% metallic iron additions) in contact with unsaturated soil half-cells that reflected the typical moisture contents of Hanford vadose zone sediments. The 99Tc diffusion profiles in the soil half cells were measured after a time lapse of ~1.9 yr. Using the concentration profiles, the 99Tc diffusivity coefficients were calculated based on Fick’s Second Law.« less

XCAT/DRASIM: a realistic CT/human-model simulation package

NASA Astrophysics Data System (ADS)

Fung, George S. K.; Stierstorfer, Karl; Segars, W. Paul; Taguchi, Katsuyuki; Flohr, Thomas G.; Tsui, Benjamin M. W.

2011-03-01

The aim of this research is to develop a complete CT/human-model simulation package by integrating the 4D eXtended CArdiac-Torso (XCAT) phantom, a computer generated NURBS surface based phantom that provides a realistic model of human anatomy and respiratory and cardiac motions, and the DRASIM (Siemens Healthcare) CT-data simulation program. Unlike other CT simulation tools which are based on simple mathematical primitives or voxelized phantoms, this new simulation package has the advantages of utilizing a realistic model of human anatomy and physiological motions without voxelization and with accurate modeling of the characteristics of clinical Siemens CT systems. First, we incorporated the 4D XCAT anatomy and motion models into DRASIM by implementing a new library which consists of functions to read-in the NURBS surfaces of anatomical objects and their overlapping order and material properties in the XCAT phantom. Second, we incorporated an efficient ray-tracing algorithm for line integral calculation in DRASIM by computing the intersection points of the rays cast from the x-ray source to the detector elements through the NURBS surfaces of the multiple XCAT anatomical objects along the ray paths. Third, we evaluated the integrated simulation package by performing a number of sample simulations of multiple x-ray projections from different views followed by image reconstruction. The initial simulation results were found to be promising by qualitative evaluation. In conclusion, we have developed a unique CT/human-model simulation package which has great potential as a tool in the design and optimization of CT scanners, and the development of scanning protocols and image reconstruction methods for improving CT image quality and reducing radiation dose.

Solvation Structure and Thermodynamic Mapping (SSTMap): An Open-Source, Flexible Package for the Analysis of Water in Molecular Dynamics Trajectories.

PubMed

Haider, Kamran; Cruz, Anthony; Ramsey, Steven; Gilson, Michael K; Kurtzman, Tom

2018-01-09

We have developed SSTMap, a software package for mapping structural and thermodynamic water properties in molecular dynamics trajectories. The package introduces automated analysis and mapping of local measures of frustration and enhancement of water structure. The thermodynamic calculations are based on Inhomogeneous Fluid Solvation Theory (IST), which is implemented using both site-based and grid-based approaches. The package also extends the applicability of solvation analysis calculations to multiple molecular dynamics (MD) simulation programs by using existing cross-platform tools for parsing MD parameter and trajectory files. SSTMap is implemented in Python and contains both command-line tools and a Python module to facilitate flexibility in setting up calculations and for automated generation of large data sets involving analysis of multiple solutes. Output is generated in formats compatible with popular Python data science packages. This tool will be used by the molecular modeling community for computational analysis of water in problems of biophysical interest such as ligand binding and protein function.

Optical Excitations and Energy Transfer in Nanoparticle Waveguides

DTIC Science & Technology

2009-03-01

All calculations were performed using our own codes given in the Appendix section. The calculations were performed using Scilab programming package...January 2007, invited Speaker) 12. Scilab is a free software compatible to the famous Matlab package. It can be found at their webpage http

The Model 9977 Radioactive Material Packaging Primer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abramczyk, G.

2015-10-09

The Model 9977 Packaging is a single containment drum style radioactive material (RAM) shipping container designed, tested and analyzed to meet the performance requirements of Title 10 the Code of Federal Regulations Part 71. A radioactive material shipping package, in combination with its contents, must perform three functions (please note that the performance criteria specified in the Code of Federal Regulations have alternate limits for normal operations and after accident conditions): Containment, the package must “contain” the radioactive material within it; Shielding, the packaging must limit its users and the public to radiation doses within specified limits; and Subcriticality, themore » package must maintain its radioactive material as subcritical« less

Technical Review Report for the Model 9978-96 Package Safety Analysis Report for Packaging (S-SARP-G-00002, Revision 1, March 2009)

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, M

2009-03-06

This Technical Review Report (TRR) documents the review, performed by Lawrence Livermore National Laboratory (LLNL) Staff, at the request of the Department of Energy (DOE), on the 'Safety Analysis Report for Packaging (SARP), Model 9978 B(M)F-96', Revision 1, March 2009 (S-SARP-G-00002). The Model 9978 Package complies with 10 CFR 71, and with 'Regulations for the Safe Transport of Radioactive Material-1996 Edition (As Amended, 2000)-Safety Requirements', International Atomic Energy Agency (IAEA) Safety Standards Series No. TS-R-1. The Model 9978 Packaging is designed, analyzed, fabricated, and tested in accordance with Section III of the American Society of Mechanical Engineers Boiler and Pressuremore » Vessel Code (ASME B&PVC). The review presented in this TRR was performed using the methods outlined in Revision 3 of the DOE's 'Packaging Review Guide (PRG) for Reviewing Safety Analysis Reports for Packages'. The format of the SARP follows that specified in Revision 2 of the Nuclear Regulatory Commission's Regulatory Guide 7.9, i.e., 'Standard Format and Content of Part 71 Applications for Approval of Packages for Radioactive Material'. Although the two documents are similar in their content, they are not identical. Formatting differences have been noted in this TRR, where appropriate. The Model 9978 Packaging is a single containment package, using a 5-inch containment vessel (5CV). It uses a nominal 35-gallon drum package design. In comparison, the Model 9977 Packaging uses a 6-inch containment vessel (6CV). The Model 9977 and Model 9978 Packagings were developed concurrently, and they were referred to as the General Purpose Fissile Material Package, Version 1 (GPFP). Both packagings use General Plastics FR-3716 polyurethane foam as insulation and as impact limiters. The 5CV is used as the Primary Containment Vessel (PCV) in the Model 9975-96 Packaging. The Model 9975-96 Packaging also has the 6CV as its Secondary Containment Vessel (SCV). In comparison, the Model 9975 Packagings use Celotex{trademark} for insulation and as impact limiters. To provide a historical perspective, it is noted that the Model 9975-96 Packaging is a 35-gallon drum package design that has evolved from a family of packages designed by DOE contractors at the Savannah River Site. Earlier package designs, i.e., the Model 9965, the Model 9966, the Model 9967, and the Model 9968 Packagings, were originally designed and certified in the early 1980s. In the 1990s, updated package designs that incorporated design features consistent with the then-newer safety requirements were proposed. The updated package designs at the time were the Model 9972, the Model 9973, the Model 9974, and the Model 9975 Packagings, respectively. The Model 9975 Package was certified by the Packaging Certification Program, under the Office of Safety Management and Operations. The Model 9978 Package has six Content Envelopes: C.1 ({sup 238}Pu Heat Sources), C.2 ( Pu/U Metals), C.3 (Pu/U Oxides, Reserved), C.4 (U Metal or Alloy), C.5 (U Compounds), and C.6 (Samples and Sources). Per 10 CFR 71.59 (Code of Federal Regulations), the value of N is 50 for the Model 9978 Package leading to a Criticality Safety Index (CSI) of 1.0. The Transport Index (TI), based on dose rate, is calculated to be a maximum of 4.1.« less

A mathematical approach to beam matching

PubMed Central

Manikandan, A; Nandy, M; Gossman, M S; Sureka, C S; Ray, A; Sujatha, N

2013-01-01

Objective: This report provides the mathematical commissioning instructions for the evaluation of beam matching between two different linear accelerators. Methods: Test packages were first obtained including an open beam profile, a wedge beam profile and a depth–dose curve, each from a 10×10 cm2 beam. From these plots, a spatial error (SE) and a percentage dose error were introduced to form new plots. These three test package curves and the associated error curves were then differentiated in space with respect to dose for a first and second derivative to determine the slope and curvature of each data set. The derivatives, also known as bandwidths, were analysed to determine the level of acceptability for the beam matching test described in this study. Results: The open and wedged beam profiles and depth–dose curve in the build-up region were determined to match within 1% dose error and 1-mm SE at 71.4% and 70.8% for of all points, respectively. For the depth–dose analysis specifically, beam matching was achieved for 96.8% of all points at 1%/1 mm beyond the depth of maximum dose. Conclusion: To quantify the beam matching procedure in any clinic, the user needs to merely generate test packages from their reference linear accelerator. It then follows that if the bandwidths are smooth and continuous across the profile and depth, there is greater likelihood of beam matching. Differentiated spatial and percentage variation analysis is appropriate, ideal and accurate for this commissioning process. Advances in knowledge: We report a mathematically rigorous formulation for the qualitative evaluation of beam matching between linear accelerators. PMID:23995874

Equivalent square formula for determining the surface dose of rectangular field from 6 MV therapeutic photon beam.

PubMed

Apipunyasopon, Lukkana; Srisatit, Somyot; Phaisangittisakul, Nakorn

2013-09-06

The purpose of the study was to investigate the use of the equivalent square formula for determining the surface dose from a rectangular photon beam. A 6 MV therapeutic photon beam delivered from a Varian Clinac 23EX medical linear accelerator was modeled using the EGS4nrc Monte Carlo simulation package. It was then used to calculate the dose in the build-up region from both square and rectangular fields. The field patterns were defined by various settings of the X- and Y-collimator jaw ranging from 5 to 20 cm. Dose measurements were performed using a thermoluminescence dosimeter and a Markus parallel-plate ionization chamber on the four square fields (5 × 5, 10 × 10, 15 × 15, and 20 × 20 cm2). The surface dose was acquired by extrapolating the build-up doses to the surface. An equivalent square for a rectangular field was determined using the area-to-perimeter formula, and the surface dose of the equivalent square was estimated using the square-field data. The surface dose of square field increased linearly from approximately 10% to 28% as the side of the square field increased from 5 to 20 cm. The influence of collimator exchange on the surface dose was found to be not significant. The difference in the percentage surface dose of the rectangular field compared to that of the relevant equivalent square was insignificant and can be clinically neglected. The use of the area-to-perimeter formula for an equivalent square field can provide a clinically acceptable surface dose estimation for a rectangular field from a 6 MV therapy photon beam.

VirtualDose: a software for reporting organ doses from CT for adult and pediatric patients

NASA Astrophysics Data System (ADS)

Ding, Aiping; Gao, Yiming; Liu, Haikuan; Caracappa, Peter F.; Long, Daniel J.; Bolch, Wesley E.; Liu, Bob; Xu, X. George

2015-07-01

This paper describes the development and testing of VirtualDose—a software for reporting organ doses for adult and pediatric patients who undergo x-ray computed tomography (CT) examinations. The software is based on a comprehensive database of organ doses derived from Monte Carlo (MC) simulations involving a library of 25 anatomically realistic phantoms that represent patients of different ages, body sizes, body masses, and pregnant stages. Models of GE Lightspeed Pro 16 and Siemens SOMATOM Sensation 16 scanners were carefully validated for use in MC dose calculations. The software framework is designed with the ‘software as a service (SaaS)’ delivery concept under which multiple clients can access the web-based interface simultaneously from any computer without having to install software locally. The RESTful web service API also allows a third-party picture archiving and communication system software package to seamlessly integrate with VirtualDose’s functions. Software testing showed that VirtualDose was compatible with numerous operating systems including Windows, Linux, Apple OS X, and mobile and portable devices. The organ doses from VirtualDose were compared against those reported by CT-Expo and ImPACT—two dosimetry tools that were based on the stylized pediatric and adult patient models that were known to be anatomically simple. The organ doses reported by VirtualDose differed from those reported by CT-Expo and ImPACT by as much as 300% in some of the patient models. These results confirm the conclusion from past studies that differences in anatomical realism offered by stylized and voxel phantoms have caused significant discrepancies in CT dose estimations.

Oral penicillin prescribing for children in the UK: a comparison with BNF for Children age-band recommendations

PubMed Central

Saxena, Sonia; Ismael, Zareen; Murray, Macey L; Barker, Charlotte; Wong, Ian CK; Sharland, Mike; Long, Paul F

2014-01-01

Background The British National Formulary for Children (BNFC) recommends dosing oral penicillins according to age-bands, weight-bands, or weight-based calculations. Because of the rising prevalence of childhood obesity, age-band-based prescribing could lead to subtherapeutic dosing. Aim To investigate actual oral penicillin prescribing by GPs in the UK with reference to the current BNFC age-band recommendations. Design and setting Descriptive analysis of UK prescriptions in the 2010 IMS Disease-Analyzer database (IMS-DA). Method A detailed database analysis was undertaken of oral penicillin prescriptions for 0–18 year olds from the 2010 IMS-DA. The prescription analysis included all available data on formulation, strength (mg), prescription quantity unit, package size, prescribed quantity, and volume. Results Considering amoxicillin alone, no infants (aged <1 year) were prescribed the BNFC 2011 edition recommended unit dose (62.5 mg), while the majority received double the dose (125 mg); among children aged 1–5 years, 96% were prescribed the recommended unit dose (125 mg), but 40% of 6–12 year olds and 70% of 12–18 year olds were prescribed unit doses below the BNFC recommendations. For otitis media, only those children aged <1 year received the recommended dose of amoxicillin (40–90 mg/kg/day). Similar variations in dosing across age-bands were observed for phenoxymethylpenicillin and flucloxacillin. Conclusion There is wide variation in the dosing of penicillins for children in UK primary care, with very few children being prescribed the current national recommended doses. There is an urgent need to review dosing guidelines, in relation to the weights of children today. PMID:24686886

Drug packaging in 2015: risky industry choices and lax regulation.

PubMed

2016-06-01

Prescrire examined the packaging quality of 240 drugs in 2015. No new advances were identified, but drug packaging continues to expose patients to a variety of dangers. Some past advances persist: for example, INNs are often more legible, and recent patient leaflets tend to be clearer and more informative. But these measures are not applied to all drugs, and are rarely applied retroactively to older drugs. The overall picture in 2015 is that many drugs are difficult to identify, risky or downright dangerous to prepare, or supplied with patient leaflets that fail to correctly inform patients about their medication. And measures to prevent drug poisoning in children need to be completely rethought. It is high time for regulators and policy makers to take the issue of drug packaging seriously, so blatant are the signs of their failure to do so: the increasing use of bulk bottles for new drugs; failure to implement guidelines on safe drug packaging (unit-dose presentations, appropriate dosing devices, etc.); and expanding umbrella brands which, given the dangers they pose to patients, should be banned instead. All things considered, healthcare professionals and patients must remain vigilant and report any dangers they identify. A major European initiative on drug packaging is becoming increasingly necessary.

Effects of gamma radiation on commercial food packaging films—study of changes in UV/VIS spectra

NASA Astrophysics Data System (ADS)

Moura, E. A. B.; Ortiz, A. V.; Wiebeck, H.; Paula, A. B. A.; Silva, A. L. A.; Silva, L. G. A.

2004-09-01

The effects of gamma irradiation doses up to 100 kGy on the optical properties of different commercial packaging films were studied in this paper. The packaging films analyzed were: polyethylene "LDPE", amide 6-amide 6.6 copolymer "PA6-PA6.6" and poly(ethylene terephthalate) "PET". An investigation on film samples before and after irradiation was performed by UV/VIS spectroscopy. The results showed that, in the absorption spectra of irradiated LDPE and PA6-PA6.6 films, a red-shift in the wavelength of the UV cutoff and a marked reduction in % transmittance (at low wavelengths) occur with increasing radiation dose. With respect to PET samples, no significant changes were observed in either light absorption or transmittance.

StreamThermal: A software package for calculating thermal metrics from stream temperature data

USGS Publications Warehouse

Tsang, Yin-Phan; Infante, Dana M.; Stewart, Jana S.; Wang, Lizhu; Tingly, Ralph; Thornbrugh, Darren; Cooper, Arthur; Wesley, Daniel

2016-01-01

Improving quality and better availability of continuous stream temperature data allows natural resource managers, particularly in fisheries, to understand associations between different characteristics of stream thermal regimes and stream fishes. However, there is no convenient tool to efficiently characterize multiple metrics reflecting stream thermal regimes with the increasing amount of data. This article describes a software program packaged as a library in R to facilitate this process. With this freely-available package, users will be able to quickly summarize metrics that describe five categories of stream thermal regimes: magnitude, variability, frequency, timing, and rate of change. The installation and usage instruction of this package, the definition of calculated thermal metrics, as well as the output format from the package are described, along with an application showing the utility for multiple metrics. We believe this package can be widely utilized by interested stakeholders and greatly assist more studies in fisheries.

Gas flow calculation method of a ramjet engine

NASA Astrophysics Data System (ADS)

Kostyushin, Kirill; Kagenov, Anuar; Eremin, Ivan; Zhiltsov, Konstantin; Shuvarikov, Vladimir

2017-11-01

At the present study calculation methodology of gas dynamics equations in ramjet engine is presented. The algorithm is based on Godunov`s scheme. For realization of calculation algorithm, the system of data storage is offered, the system does not depend on mesh topology, and it allows using the computational meshes with arbitrary number of cell faces. The algorithm of building a block-structured grid is given. Calculation algorithm in the software package "FlashFlow" is implemented. Software package is verified on the calculations of simple configurations of air intakes and scramjet models.

2010 drug packaging review: identifying problems to prevent errors.

PubMed

2011-06-01

Prescrire's analyses showed that the quality of drug packaging in 2010 still left much to be desired. Potentially dangerous packaging remains a significant problem: unclear labelling is source of medication errors; dosing devices for some psychotropic drugs create a risk of overdose; child-proof caps are often lacking; and too many patient information leaflets are misleading or difficult to understand. Everything that is needed for safe drug packaging is available; it is now up to regulatory agencies and drug companies to act responsibly. In the meantime, health professionals can help their patients by learning to identify the pitfalls of drug packaging and providing safe information to help prevent medication errors.

ppcor: An R Package for a Fast Calculation to Semi-partial Correlation Coefficients.

PubMed

Kim, Seongho

2015-11-01

Lack of a general matrix formula hampers implementation of the semi-partial correlation, also known as part correlation, to the higher-order coefficient. This is because the higher-order semi-partial correlation calculation using a recursive formula requires an enormous number of recursive calculations to obtain the correlation coefficients. To resolve this difficulty, we derive a general matrix formula of the semi-partial correlation for fast computation. The semi-partial correlations are then implemented on an R package ppcor along with the partial correlation. Owing to the general matrix formulas, users can readily calculate the coefficients of both partial and semi-partial correlations without computational burden. The package ppcor further provides users with the level of the statistical significance with its test statistic.

Calculation Package for the Analysis of Performance of Cells 1-6, with Underdrain, of the Environmental Management Waste Management Facility Oak Ridge, Tennessee

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzales D.

2010-03-30

This calculation package presents the results of an assessment of the performance of the 6 cell design of the Environmental Management Waste Management Facility (EMWMF). The calculations show that the new cell 6 design at the EMWMF meets the current WAC requirement. QA/QC steps were taken to verify the input/output data for the risk model and data transfer from modeling output files to tables and calculation.

Function Package for Computing Quantum Resource Measures

NASA Astrophysics Data System (ADS)

Huang, Zhiming

2018-05-01

In this paper, we present a function package for to calculate quantum resource measures and dynamics of open systems. Our package includes common operators and operator lists, frequently-used functions for computing quantum entanglement, quantum correlation, quantum coherence, quantum Fisher information and dynamics in noisy environments. We briefly explain the functions of the package and illustrate how to use the package with several typical examples. We expect that this package is a useful tool for future research and education.

CPMC-Lab: A MATLAB package for Constrained Path Monte Carlo calculations

NASA Astrophysics Data System (ADS)

Nguyen, Huy; Shi, Hao; Xu, Jie; Zhang, Shiwei

2014-12-01

We describe CPMC-Lab, a MATLAB program for the constrained-path and phaseless auxiliary-field Monte Carlo methods. These methods have allowed applications ranging from the study of strongly correlated models, such as the Hubbard model, to ab initio calculations in molecules and solids. The present package implements the full ground-state constrained-path Monte Carlo (CPMC) method in MATLAB with a graphical interface, using the Hubbard model as an example. The package can perform calculations in finite supercells in any dimensions, under periodic or twist boundary conditions. Importance sampling and all other algorithmic details of a total energy calculation are included and illustrated. This open-source tool allows users to experiment with various model and run parameters and visualize the results. It provides a direct and interactive environment to learn the method and study the code with minimal overhead for setup. Furthermore, the package can be easily generalized for auxiliary-field quantum Monte Carlo (AFQMC) calculations in many other models for correlated electron systems, and can serve as a template for developing a production code for AFQMC total energy calculations in real materials. Several illustrative studies are carried out in one- and two-dimensional lattices on total energy, kinetic energy, potential energy, and charge- and spin-gaps.

Validation of the new code package APOLLO2.8 for accurate PWR neutronics calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santamarina, A.; Bernard, D.; Blaise, P.

2013-07-01

This paper summarizes the Qualification work performed to demonstrate the accuracy of the new APOLLO2.S/SHEM-MOC package based on JEFF3.1.1 nuclear data file for the prediction of PWR neutronics parameters. This experimental validation is based on PWR mock-up critical experiments performed in the EOLE/MINERVE zero-power reactors and on P.I. Es on spent fuel assemblies from the French PWRs. The Calculation-Experiment comparison for the main design parameters is presented: reactivity of UOX and MOX lattices, depletion calculation and fuel inventory, reactivity loss with burnup, pin-by-pin power maps, Doppler coefficient, Moderator Temperature Coefficient, Void coefficient, UO{sub 2}-Gd{sub 2}O{sub 3} poisoning worth, Efficiency ofmore » Ag-In-Cd and B4C control rods, Reflector Saving for both standard 2-cm baffle and GEN3 advanced thick SS reflector. From this qualification process, calculation biases and associated uncertainties are derived. This code package APOLLO2.8 is already implemented in the ARCADIA new AREVA calculation chain for core physics and is currently under implementation in the future neutronics package of the French utility Electricite de France. (authors)« less

batman: BAsic Transit Model cAlculatioN in Python

NASA Astrophysics Data System (ADS)

Kreidberg, Laura

2015-11-01

I introduce batman, a Python package for modeling exoplanet transit light curves. The batman package supports calculation of light curves for any radially symmetric stellar limb darkening law, using a new integration algorithm for models that cannot be quickly calculated analytically. The code uses C extension modules to speed up model calculation and is parallelized with OpenMP. For a typical light curve with 100 data points in transit, batman can calculate one million quadratic limb-darkened models in 30 seconds with a single 1.7 GHz Intel Core i5 processor. The same calculation takes seven minutes using the four-parameter nonlinear limb darkening model (computed to 1 ppm accuracy). Maximum truncation error for integrated models is an input parameter that can be set as low as 0.001 ppm, ensuring that the community is prepared for the precise transit light curves we anticipate measuring with upcoming facilities. The batman package is open source and publicly available at https://github.com/lkreidberg/batman .

SEMModComp: An R Package for Calculating Likelihood Ratio Tests for Mean and Covariance Structure Models

ERIC Educational Resources Information Center

Levy, Roy

2010-01-01

SEMModComp, a software package for conducting likelihood ratio tests for mean and covariance structure modeling is described. The package is written in R and freely available for download or on request.

Cilazapril stability in the presence of hydrochlorothiazide in model mixtures and fixed dose combination.

PubMed

Paszun, Sylwia K; Stanisz, Beata J; Gradowska, Agnieszka

2013-01-01

The presented study aimed at the evaluation of hydrochlorothiazide influence on cilazapril stability in model mixture and fixed dose tablet formulation. The degradation of cilazapril in the presence of hydrochlorothiazide took place according to autocatalytic reaction kinetic mechanism, described mathematically by Prout-Tompkins equation. Hydrochlorothiazide coexistence with cilazapril in model mixture and fixed dose tablet without blister package accelerated cilazapril degradation in comparison with degradation of cilazapril substance. Values of reaction induction time shortened, while those of observed reaction rate constant increased. Increasing values of relative humidity and temperature have negative impact on cilazapril stability. Determined semi-logarithmic relationships: In k = f(RH) and Arrhenius ln k = f(1/T) are linear and are cilazapril stability predictive. The blister (OPA/Alu/PVC//Alu) package of fixed dose tablets, constitutes absolute moisture protection and prevent cilazapril--hydrochlorothiazide interaction occurrence.

Stopping power and dose calculations with analytical and Monte Carlo methods for protons and prompt gamma range verification

NASA Astrophysics Data System (ADS)

Usta, Metin; Tufan, Mustafa Çağatay; Aydın, Güral; Bozkurt, Ahmet

2018-07-01

In this study, we have performed the calculations stopping power, depth dose, and range verification for proton beams using dielectric and Bethe-Bloch theories and FLUKA, Geant4 and MCNPX Monte Carlo codes. In the framework, as analytical studies, Drude model was applied for dielectric theory and effective charge approach with Roothaan-Hartree-Fock charge densities was used in Bethe theory. In the simulations different setup parameters were selected to evaluate the performance of three distinct Monte Carlo codes. The lung and breast tissues were investigated are considered to be related to the most common types of cancer throughout the world. The results were compared with each other and the available data in literature. In addition, the obtained results were verified with prompt gamma range data. In both stopping power values and depth-dose distributions, it was found that the Monte Carlo values give better results compared with the analytical ones while the results that agree best with ICRU data in terms of stopping power are those of the effective charge approach between the analytical methods and of the FLUKA code among the MC packages. In the depth dose distributions of the examined tissues, although the Bragg curves for Monte Carlo almost overlap, the analytical ones show significant deviations that become more pronounce with increasing energy. Verifications with the results of prompt gamma photons were attempted for 100-200 MeV protons which are regarded important for proton therapy. The analytical results are within 2%-5% and the Monte Carlo values are within 0%-2% as compared with those of the prompt gammas.

Low-dose irradiation with modified atmosphere packaging for mango against the Oriental Fruit Fly (Diptera: Tephritidae)

USDA-ARS?s Scientific Manuscript database

Irradiation and vapor–heating treatments are commonly used to disinfest the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera:Tephritidae), and other pests on mango fruits before export from Thailand to foreign markets. Modified atmosphere packaging (MAP) used during export of mangoes create...

Mediate gamma radiation effects on some packaged food items

NASA Astrophysics Data System (ADS)

Inamura, Patricia Y.; Uehara, Vanessa B.; Teixeira, Christian A. H. M.; del Mastro, Nelida L.

2012-08-01

For most of prepackaged foods a 10 kGy radiation dose is considered the maximum dose needed; however, the commercially available and practically accepted packaging materials must be suitable for such application. This work describes the application of ionizing radiation on several packaged food items, using 5 dehydrated food items, 5 ready-to-eat meals and 5 ready-to-eat food items irradiated in a 60Co gamma source with a 3 kGy dose. The quality evaluation of the irradiated samples was performed 2 and 8 months after irradiation. Microbiological analysis (bacteria, fungus and yeast load) was performed. The sensory characteristics were established for appearance, aroma, texture and flavor attributes were also established. From these data, the acceptability of all irradiated items was obtained. All ready-to-eat food items assayed like manioc flour, some pâtés and blocks of raw brown sugar and most of ready-to-eat meals like sausages and chicken with legumes were considered acceptable for microbial and sensory characteristics. On the other hand, the dehydrated food items chosen for this study, such as dehydrated bacon potatoes or pea soups were not accepted by the sensory analysis. A careful dose choice and special irradiation conditions must be used in order to achieve sensory acceptability needed for the commercialization of specific irradiated food items.

Recent trends and future of pharmaceutical packaging technology

PubMed Central

Zadbuke, Nityanand; Shahi, Sadhana; Gulecha, Bhushan; Padalkar, Abhay; Thube, Mahesh

2013-01-01

The pharmaceutical packaging market is constantly advancing and has experienced annual growth of at least five percent per annum in the past few years. The market is now reckoned to be worth over $20 billion a year. As with most other packaged goods, pharmaceuticals need reliable and speedy packaging solutions that deliver a combination of product protection, quality, tamper evidence, patient comfort and security needs. Constant innovations in the pharmaceuticals themselves such as, blow fill seal (BFS) vials, anti-counterfeit measures, plasma impulse chemical vapor deposition (PICVD) coating technology, snap off ampoules, unit dose vials, two-in-one prefilled vial design, prefilled syringes and child-resistant packs have a direct impact on the packaging. The review details several of the recent pharmaceutical packaging trends that are impacting packaging industry, and offers some predictions for the future. PMID:23833515

Variation in Prescribing Patterns and Therapeutic Drug Monitoring of Intravenous Busulfan in Pediatric Hematopoietic Cell Transplant Recipients

PubMed Central

McCune, Jeannine S.; Baker, K. Scott; Blough, David K.; Gamis, Alan; Bemer, Meagan J.; Kelton-Rehkopf, Megan C.; Winter, Laura; Barrett, Jeffrey S.

2016-01-01

Personalizing intravenous (IV) busulfan doses in children using therapeutic drug monitoring (TDM) is an integral component of hematopoietic cell transplant. The authors sought to characterize initial dosing and TDM of IV busulfan, along with factors associated with busulfan clearance, in 729 children who underwent busulfan TDM from December 2005 to December 2008. The initial IV busulfan dose in children weighing ≤12 kg ranged 4.8-fold, with only 19% prescribed the package insert dose of 1.1 mg/kg. In those children weighing >12 kg, the initial dose ranged 5.4-fold, and 79% were prescribed the package insert dose. The initial busulfan dose achieved the target exposure in only 24.3% of children. A wide range of busulfan exposures were targeted for children with the same disease (eg, 39 target busulfan exposures for the 264 children diagnosed with acute myeloid leukemia). Considerable heterogeneity exists regarding when TDM is conducted and the number of pharmacokinetic samples obtained. Busulfan clearance varied by age and dosing frequency but not by underlying disease. The authors’ group is currently evaluating how using population pharmacokinetics to optimize initial busulfan dose and TDM (eg, limited sampling schedule in conjunction with maximum a posteriori Bayesian estimation) may affect clinical outcomes in children. PMID:23444282

Cocaine smuggling in the gastrointestinal tract resulting in mechanical pylorostenosis.

PubMed

Sein Anand, Jacek; Chodorowski, Zygmunt; Masal, Andrzej; Nowak-Banasik, Livia

2005-01-01

A 45-year-old male, body packer, who confessed to have swallowed 44 packages of cocaine in a total dose of approx. 360 g, was admitted to hospital because of clinical signs of acute intoxication with cocaine followed by ileus. The emergency surgical gastrotomy was initiated, and the conglomerate of Scotch tape and packages with cocaine were removed. Small rupture of one package of cocaine in a body packer stomach caused acute poisoning with cocaine, confirmed additionally by the presence of its metabolites in the urine. Mechanical pylorostenosis provoked by cocaine packages required emergency surgical operation.

Dose and linear energy transfer spectral measurements for the supersonic transport program

NASA Technical Reports Server (NTRS)

Philbrick, R. B.

1972-01-01

The purpose of the package, called the high altitude radiation instrumentation system (HARIS), is to measure the radiation hazard to supersonic transport passengers from solar and galactic cosmic rays. The HARIS includes gaseous linear energy transfer spectrometer, a tissue equivalent ionization chamber, and a geiger meuller tube. The HARIS is flown on RB-57F aircraft at 60,000 feet. Data from the HARIS are reduced to give rad and rem dose rates measured by the package during the flights. Results presented include ambient data obtained on background flights, altitude comparison data, and solar flare data.

QEDMOD: Fortran program for calculating the model Lamb-shift operator

NASA Astrophysics Data System (ADS)

Shabaev, V. M.; Tupitsyn, I. I.; Yerokhin, V. A.

2018-02-01

We present Fortran package QEDMOD for computing the model QED operator hQED that can be used to account for the Lamb shift in accurate atomic-structure calculations. The package routines calculate the matrix elements of hQED with the user-specified one-electron wave functions. The operator can be used to calculate Lamb shift in many-electron atomic systems with a typical accuracy of few percent, either by evaluating the matrix element of hQED with the many-electron wave function, or by adding hQED to the Dirac-Coulomb-Breit Hamiltonian.

Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

NASA Astrophysics Data System (ADS)

Nogueira, P.; Zankl, M.; Schlattl, H.; Vaz, P.

2011-11-01

The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation—the germinative cells—absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations.

PubMed

Nogueira, P; Zankl, M; Schlattl, H; Vaz, P

2011-11-07

The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

Monte Carlo determination of the conversion coefficients Hp(3)/Ka in a right cylinder phantom with 'PENELOPE' code. Comparison with 'MCNP' simulations.

PubMed

Daures, J; Gouriou, J; Bordy, J M

2011-03-01

This work has been performed within the frame of the European Union ORAMED project (Optimisation of RAdiation protection for MEDical staff). The main goal of the project is to improve standards of protection for medical staff for procedures resulting in potentially high exposures and to develop methodologies for better assessing and for reducing, exposures to medical staff. The Work Package WP2 is involved in the development of practical eye-lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP-4C code of the conversion factors related to the operational quantity H(p)(3). In this study, a set of energy- and angular-dependent conversion coefficients (H(p)(3)/K(a)), in the newly proposed square cylindrical phantom made of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE and MCNP5. The H(p)(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At a low-photon energy (up to 1 MeV), the two results obtained with the two methods are consistent. Nevertheless, large differences are showed at a higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the MCNP-4C code published by ENEA quite agree with the kerma approximation calculations obtained with PENELOPE. We also performed the same calculations with the code MCNP5 with two types of tallies: F6 for kerma approximation and *F8 for estimating the absorbed dose that is, as known, due to secondary electrons. PENELOPE and MCNP5 results agree for the kerma approximation and for the absorbed dose calculation of H(p)(3) and prove that, for photon energies larger than 1 MeV, the transport of the secondary electrons has to be taken into account.

Technological challenges of addressing new and more complex migrating products from novel food packaging materials.

PubMed

Munro, Ian C; Haighton, Lois A; Lynch, Barry S; Tafazoli, Shahrzad

2009-12-01

The risk assessment of migration products resulting from packaging material has and continues to pose a difficult challenge. In most jurisdictions, there are regulatory requirements for the approval or notification of food contact substances that will be used in packaging. These processes generally require risk assessment to ensure safety concerns are addressed. The science of assessing food contact materials was instrumental in the development of the concept of Threshold of Regulation and the Threshold of Toxicological Concern procedures. While the risk assessment process is in place, the technology of food packaging continues to evolve to include new initiatives, such as the inclusion of antimicrobial substances or enzyme systems to prevent spoilage, use of plastic packaging intended to remain on foods as they are being cooked, to the introduction of more rigid, stable and reusable materials, and active packaging to extend the shelf-life of food. Each new technology brings with it the potential for exposure to new and possibly novel substances as a result of migration, interaction with other chemical packaging components, or, in the case of plastics now used in direct cooking of products, degradation products formed during heating. Furthermore, the presence of trace levels of certain chemicals from packaging that were once accepted as being of low risk based on traditional toxicology studies are being challenged on the basis of reports of adverse effects, particularly with respect to endocrine disruption, alleged to occur at very low doses. A recent example is the case of bisphenol A. The way forward to assess new packaging technologies and reports of very low dose effects in non-standard studies of food contact substances is likely to remain controversial. However, the risk assessment paradigm is sufficiently robust and flexible to be adapted to meet these challenges. The use of the Threshold of Regulation and the Threshold of Toxicological Concern concepts may play a critical role in the risk assessment of new food packaging technologies in the future.

QMCPACK: an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids

NASA Astrophysics Data System (ADS)

Kim, Jeongnim; Baczewski, Andrew D.; Beaudet, Todd D.; Benali, Anouar; Chandler Bennett, M.; Berrill, Mark A.; Blunt, Nick S.; Josué Landinez Borda, Edgar; Casula, Michele; Ceperley, David M.; Chiesa, Simone; Clark, Bryan K.; Clay, Raymond C., III; Delaney, Kris T.; Dewing, Mark; Esler, Kenneth P.; Hao, Hongxia; Heinonen, Olle; Kent, Paul R. C.; Krogel, Jaron T.; Kylänpää, Ilkka; Li, Ying Wai; Lopez, M. Graham; Luo, Ye; Malone, Fionn D.; Martin, Richard M.; Mathuriya, Amrita; McMinis, Jeremy; Melton, Cody A.; Mitas, Lubos; Morales, Miguel A.; Neuscamman, Eric; Parker, William D.; Pineda Flores, Sergio D.; Romero, Nichols A.; Rubenstein, Brenda M.; Shea, Jacqueline A. R.; Shin, Hyeondeok; Shulenburger, Luke; Tillack, Andreas F.; Townsend, Joshua P.; Tubman, Norm M.; Van Der Goetz, Brett; Vincent, Jordan E.; ChangMo Yang, D.; Yang, Yubo; Zhang, Shuai; Zhao, Luning

2018-05-01

QMCPACK is an open source quantum Monte Carlo package for ab initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater–Jastrow type trial wavefunctions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary-field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performance computing architectures, including multicore central processing unit and graphical processing unit systems. We detail the program’s capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://qmcpack.org.

QMCPACK: an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids.

PubMed

Kim, Jeongnim; Baczewski, Andrew T; Beaudet, Todd D; Benali, Anouar; Bennett, M Chandler; Berrill, Mark A; Blunt, Nick S; Borda, Edgar Josué Landinez; Casula, Michele; Ceperley, David M; Chiesa, Simone; Clark, Bryan K; Clay, Raymond C; Delaney, Kris T; Dewing, Mark; Esler, Kenneth P; Hao, Hongxia; Heinonen, Olle; Kent, Paul R C; Krogel, Jaron T; Kylänpää, Ilkka; Li, Ying Wai; Lopez, M Graham; Luo, Ye; Malone, Fionn D; Martin, Richard M; Mathuriya, Amrita; McMinis, Jeremy; Melton, Cody A; Mitas, Lubos; Morales, Miguel A; Neuscamman, Eric; Parker, William D; Pineda Flores, Sergio D; Romero, Nichols A; Rubenstein, Brenda M; Shea, Jacqueline A R; Shin, Hyeondeok; Shulenburger, Luke; Tillack, Andreas F; Townsend, Joshua P; Tubman, Norm M; Van Der Goetz, Brett; Vincent, Jordan E; Yang, D ChangMo; Yang, Yubo; Zhang, Shuai; Zhao, Luning

2018-05-16

QMCPACK is an open source quantum Monte Carlo package for ab initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater-Jastrow type trial wavefunctions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary-field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performance computing architectures, including multicore central processing unit and graphical processing unit systems. We detail the program's capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://qmcpack.org.

Use of gamma-irradiation technology in the manufacture of biopolymer-based packaging films for shelf-stable foods

NASA Astrophysics Data System (ADS)

Parra, Duclerc F.; Rodrigues, Juliana A. F. R.; Lugão, Ademar B.

2005-07-01

Gamma irradiation is an alternative method for the manufacture of sterilized packaging with increased storage stability and microbiological safety. Biopolymer-based packaging films are a potential solution to many environmental problems that have emerged from the production and accumulation of significant amounts of synthetic polymeric waste. This work was undertaken to verify the effectiveness of low-dose gamma-irradiation in obtaining biopolymer-based packaging films for shelf-stable foods. PHB polyester poly(3-hydroxybutyrate) is an interesting biodegradable polymer that has been intensely investigated as cast and sheet films, with applications in the food industry and medicine. The films obtained are, however, typically brittle, and many scientists have attempted to reduce this brittleness by blending PHB with other polymers. In the present work, PHB was blended with PEG (polyethyleneglycol) to obtain films by the casting method that were then irradiated at a dose rate of 5.72 kGy/h with a 60Co source. Samples were melted at 200 °C and quenched to 0 °C in order to evaluate film crystallinity levels by differential scanning calorimetry (DSC). DSC analyses were performed with the samples (10 mg) under N2 atmosphere, heating from -50 to 200 °C (10 °C min-1), cooling from 200 to -50 °C (10 °C min-1); and heating from -50 to 200 °C (10 °C min-1). The thermal and mechanical resistances of the films after irradiation at low doses (5, 10, 20 kGy) are discussed. Water vapour transmission decreased with increasing irradiation dose, indicating that the films' performance as water vapour barrier had improved. Critical loss of the mechanical properties was observed at 40 kGy.

A User-Friendly Software Package for HIFU Simulation

NASA Astrophysics Data System (ADS)

Soneson, Joshua E.

2009-04-01

A freely-distributed, MATLAB (The Mathworks, Inc., Natick, MA)-based software package for simulating axisymmetric high-intensity focused ultrasound (HIFU) beams and their heating effects is discussed. The package (HIFU_Simulator) consists of a propagation module which solves the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation and a heating module which solves Pennes' bioheat transfer (BHT) equation. The pressure, intensity, heating rate, temperature, and thermal dose fields are computed, plotted, the output is released to the MATLAB workspace for further user analysis or postprocessing.

Promoter classifier: software package for promoter database analysis.

PubMed

Gershenzon, Naum I; Ioshikhes, Ilya P

2005-01-01

Promoter Classifier is a package of seven stand-alone Windows-based C++ programs allowing the following basic manipulations with a set of promoter sequences: (i) calculation of positional distributions of nucleotides averaged over all promoters of the dataset; (ii) calculation of the averaged occurrence frequencies of the transcription factor binding sites and their combinations; (iii) division of the dataset into subsets of sequences containing or lacking certain promoter elements or combinations; (iv) extraction of the promoter subsets containing or lacking CpG islands around the transcription start site; and (v) calculation of spatial distributions of the promoter DNA stacking energy and bending stiffness. All programs have a user-friendly interface and provide the results in a convenient graphical form. The Promoter Classifier package is an effective tool for various basic manipulations with eukaryotic promoter sequences that usually are necessary for analysis of large promoter datasets. The program Promoter Divider is described in more detail as a representative component of the package.

SynergyFinder: a web application for analyzing drug combination dose-response matrix data.

PubMed

Ianevski, Aleksandr; He, Liye; Aittokallio, Tero; Tang, Jing

2017-08-01

Rational design of drug combinations has become a promising strategy to tackle the drug sensitivity and resistance problem in cancer treatment. To systematically evaluate the pre-clinical significance of pairwise drug combinations, functional screening assays that probe combination effects in a dose-response matrix assay are commonly used. To facilitate the analysis of such drug combination experiments, we implemented a web application that uses key functions of R-package SynergyFinder, and provides not only the flexibility of using multiple synergy scoring models, but also a user-friendly interface for visualizing the drug combination landscapes in an interactive manner. The SynergyFinder web application is freely accessible at https://synergyfinder.fimm.fi ; The R-package and its source-code are freely available at http://bioconductor.org/packages/release/bioc/html/synergyfinder.html . jing.tang@helsinki.fi. © The Author(s) 2017. Published by Oxford University Press.

Intact and Degraded Criticality Calculations for the Codisposal of Shippingport LWBR Spent Nuclear Fuel in a Waste Package

DOE Office of Scientific and Technical Information (OSTI.GOV)

L.M. Montierth

2000-09-15

The objective of this calculation is to characterize the nuclear criticality safety concerns associated with the codisposal of the U.S. Department of Energy's (DOE) Shippingport Light Water Breeder Reactor (SP LWBR) Spent Nuclear Fuel (SNF) in a 5-Defense High-Level Waste (5-DHLW) Waste Package (WP), which is to be placed in a Monitored Geologic Repository (MGR). The scope of this calculation is limited to the determination of the effective neutron multiplication factor (K{sub eff}) for intact- and degraded-mode internal configurations of the codisposal WP containing Shippingport LWBR seed-type assemblies. The results of this calculation will be used to evaluate criticality issuesmore » and support the analysis that is planed to be performed to demonstrate the viability of the codisposal concept for the MGR. This calculation is associated with the waste package design and was performed in accordance with the DOE SNF Analysis Plan for FY 2000 (See Ref. 22). The document has been prepared in accordance with the Administrative Procedure AP-3.12Q, Calculations (Ref. 23).« less

Monte carlo study of MOSFET packaging, optimised for improved energy response: single MOSFET filtration.

PubMed

Othman, M A R; Cutajar, D L; Hardcastle, N; Guatelli, S; Rosenfeld, A B

2010-09-01

Monte Carlo simulations of the energy response of a conventionally packaged single metal-oxide field effect transistors (MOSFET) detector were performed with the goal of improving MOSFET energy dependence for personal accident or military dosimetry. The MOSFET detector packaging was optimised. Two different 'drop-in' design packages for a single MOSFET detector were modelled and optimised using the GEANT4 Monte Carlo toolkit. Absorbed photon dose simulations of the MOSFET dosemeter placed in free-air response, corresponding to the absorbed doses at depths of 0.07 mm (D(w)(0.07)) and 10 mm (D(w)(10)) in a water equivalent phantom of size 30 x 30 x 30 cm(3) for photon energies of 0.015-2 MeV were performed. Energy dependence was reduced to within + or - 60 % for photon energies 0.06-2 MeV for both D(w)(0.07) and D(w)(10). Variations in the response for photon energies of 15-60 keV were 200 and 330 % for D(w)(0.07) and D(w)(10), respectively. The obtained energy dependence was reduced compared with that for conventionally packaged MOSFET detectors, which usually exhibit a 500-700 % over-response when used in free-air geometry.

Methods, software and datasets to verify DVH calculations against analytical values: Twenty years late(r)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelms, Benjamin; Stambaugh, Cassandra; Hunt, Dylan

2015-08-15

Purpose: The authors designed data, methods, and metrics that can serve as a standard, independent of any software package, to evaluate dose-volume histogram (DVH) calculation accuracy and detect limitations. The authors use simple geometrical objects at different orientations combined with dose grids of varying spatial resolution with linear 1D dose gradients; when combined, ground truth DVH curves can be calculated analytically in closed form to serve as the absolute standards. Methods: DICOM RT structure sets containing a small sphere, cylinder, and cone were created programmatically with axial plane spacing varying from 0.2 to 3 mm. Cylinders and cones were modeledmore » in two different orientations with respect to the IEC 1217 Y axis. The contours were designed to stringently but methodically test voxelation methods required for DVH. Synthetic RT dose files were generated with 1D linear dose gradient and with grid resolution varying from 0.4 to 3 mm. Two commercial DVH algorithms—PINNACLE (Philips Radiation Oncology Systems) and PlanIQ (Sun Nuclear Corp.)—were tested against analytical values using custom, noncommercial analysis software. In Test 1, axial contour spacing was constant at 0.2 mm while dose grid resolution varied. In Tests 2 and 3, the dose grid resolution was matched to varying subsampled axial contours with spacing of 1, 2, and 3 mm, and difference analysis and metrics were employed: (1) histograms of the accuracy of various DVH parameters (total volume, D{sub max}, D{sub min}, and doses to % volume: D99, D95, D5, D1, D0.03 cm{sup 3}) and (2) volume errors extracted along the DVH curves were generated and summarized in tabular and graphical forms. Results: In Test 1, PINNACLE produced 52 deviations (15%) while PlanIQ produced 5 (1.5%). In Test 2, PINNACLE and PlanIQ differed from analytical by >3% in 93 (36%) and 18 (7%) times, respectively. Excluding D{sub min} and D{sub max} as least clinically relevant would result in 32 (15%) vs 5 (2%) scored deviations for PINNACLE vs PlanIQ in Test 1, while Test 2 would yield 53 (25%) vs 17 (8%). In Test 3, statistical analyses of volume errors extracted continuously along the curves show PINNACLE to have more errors and higher variability (relative to PlanIQ), primarily due to PINNACLE’s lack of sufficient 3D grid supersampling. Another major driver for PINNACLE errors is an inconsistency in implementation of the “end-capping”; the additional volume resulting from expanding superior and inferior contours halfway to the next slice is included in the total volume calculation, but dose voxels in this expanded volume are excluded from the DVH. PlanIQ had fewer deviations, and most were associated with a rotated cylinder modeled by rectangular axial contours; for coarser axial spacing, the limited number of cross-sectional rectangles hinders the ability to render the true structure volume. Conclusions: The method is applicable to any DVH-calculating software capable of importing DICOM RT structure set and dose objects (the authors’ examples are available for download). It includes a collection of tests that probe the design of the DVH algorithm, measure its accuracy, and identify failure modes. Merits and applicability of each test are discussed.« less

Adrenaline in cardiac arrest: Prefilled syringes are faster.

PubMed

Helm, Claire; Gillett, Mark

2015-08-01

Standard ampoules and prefilled syringes of adrenaline are widely available in Australasian EDs for use in cardiac arrest. We hypothesise that prefilled syringes can be administered more rapidly and accurately when compared with the two available standard ampoules. This is a triple arm superiority study comparing the time to i.v. administration and accuracy of dosing of three currently available preparations of adrenaline. In their standard packaging, prefilled syringes were on average more than 12 s faster to administer than the 1 mL 1:1000 ampoules and more than 16 s faster than the 10 mL 1:10,000 ampoules (P < 0.01 in both comparisons). With packaging removed, the time to administration was equal for the 1 mL (1:1000) ampoule and the prefilled syringe. Accuracy of dosing was excellent with both the 10 mL (1:10 000) ampoules and prefilled syringes. The 1 mL (1:1000) ampoules delivered a small number of markedly inaccurate doses, but these did not reach statistical significance. The speed of administration of adrenaline utilising a Minijet (CSL Limited, Parkville, Victoria, Australia) is faster than using adrenaline in glass ampoules presented in their plastic packaging. Removing the plastic packaging from the 1 mL (1 mg) ampoule might result in more rapid administration similar to the Minijet. Resuscitation personnel requiring rapid access to adrenaline should consider storing it as either Minijets or ampoules devoid of packaging. These results might be extrapolatable to other clinical scenarios, including pre-hospital and anaesthesia, where other drugs are required for rapid use. © 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Improvement of calculation method for electrical parameters of short network of ore-thermal furnaces

NASA Astrophysics Data System (ADS)

Aliferov, A. I.; Bikeev, R. A.; Goreva, L. P.

2017-10-01

The paper describes a new calculation method for active and inductive resistance of split interleaved current leads packages in ore-thermal electric furnaces. The method is developed on basis of regression analysis of dependencies of active and inductive resistances of the packages on their geometrical parameters, mutual disposition and interleaving pattern. These multi-parametric calculations have been performed with ANSYS software. The proposed method allows solving split current lead electrical parameters minimization and balancing problems for ore-thermal furnaces.

It is not only the empty vials that go into the garbage can during chemotherapy drugs preparation: a cost analysis of unused chemotherapy drugs in cancer treatment.

PubMed

Ata, A; Abali, H; Yengel, E; Arican, A

2012-01-01

Cancer therapy is a costly treatment. Costs of drugs used in cancer therapy are gradually increasing with the addition of new and expensive drugs. This fact imposes obligation on reasonable drug usage. Occasionally, all of the prescribed drugs are not used for various reasons, and a number of drugs can be left over. In this study, we aimed to calculate the costs of unused chemotherapeutic drugs in our oncology clinics. A total of 117 patients with 17 different types of cancer were administered 32 cancer therapy protocols during 2 months. After administration of ideal doses of the prescribed drugs calculated on an individual basis, the number of unused drug doses in the packages was recorded and the costs of the unused drugs were calculated based on current prices of the drugs. The cumulative cost of the unused drugs calculated for all patients was US dollars (USD) 6406.93, and average cost of the drug per capita was USD 54.76. Minimal and maximal unused drug costs per drug were USD 0.29 for 5-fluorouracil, and USD 247.12 for bevacizumab, respectively. Minimal increase in drug costs per recipe was USD 0.50 for a prescription containing cyclophosphamide and 5-fluorouracil, while the total cost of bevacizumab plus irinotecan combination increased tremendously to USD 309.12. Among chemotherapeutic protocols the cheapest one was AC (adriamycin, cyclophosphamide) with USD 4.77, while the most expensive one (USD 116.02) was FOLFIRI-B (5-fluorouracil, calcium folinate, irinotecan, and bevacizumab). The important financial burden of unused drugs goes unrecognized among routine chemotherapeutic applications. In order to be able to avoid this extravagance, drug industry, prescribing physicians, and practice nurses must assume important roles.

Packaging of pharmaceuticals: still too many dangers but several encouraging initiatives.

PubMed

2007-06-01

(1) In 2006 in France, several drugs sold in poorly designed packaging exposed patients to a risk of serious adverse effects. (2) In 2006, Prescrire used a standardised methodology to examine the packaging of all new pharmaceutical products (656 different boxes) assessed in the New Products section of our French edition, la revue Prescrire. About 75% of these boxes contained tablets or capsules, mostly in blister packs. (3) Poor labelling remains a major problem. The international nonproprietary names (INN) is hard to spot on most boxes of patented brand-name drugs and is often overshadowed by the brand name. The primary packaging of many products does not even include the INN. (4) Two particularly ambiguous types of labelling are becoming more common on blister packs: pre-cut multiple-unit blister packs on which the labelling is truncated when a unit blister is removed; and blister packs on which the labelling spans two blisters, creating a risk of overdose. (5) The use of colours is frequently inappropriate. In particular, irrelevant information is often highlighted unnecessarily, while other, important information is barely visible. (6) Too many devices for oral administration create a risk of misuse. Very few are graduated in units of weight. Most are graduated in millilitres, obliging caregivers to use conversion charts and thus creating a risk of dosing errors. Devices graduated in kg bodyweight can also lead to dosing errors. (7) The labelling of some injectable drugs is barely legible. The various models of plastic ampoules, that are gradually replacing glass ampoules, can represent a danger because they resemble other plastic ampoules containing products administered by different routes. Packaging that does not provide a syringe or needle can cause problems for caregivers and represents another potential source of error. (8) Many of the patient information leaflets examined in 2006 had the same flaws as previously observed, i.e. uneven information quality, discrepancies between different sections, and out-of-date information. More and more French leaflets now include insets offering "Health Advice". There are better and worse examples, but there is no guarantee that they have been properly reviewed by the regulatory agency. (9) Increasingly drug boxes include pictograms, even though several studies have shown they are often difficult to interpret. And most boxes of generics also now include standard dosing schedules that are not always appropriate and may create a risk of dosing errors with potentially serious consequences. (10) 67 multidose bottles examined in 2006 had no childproof safety cap. Some contained psychotropics, which can have life-threatening effects if accidentally consumed in large amounts. (11) Some manufacturers have adopted realistic solutions to these problems. In particular, generics manufacturers again improved product labelling in 2006 (emphasis on the INN), appropriate use of colours for dose differentiation, and, encouragingly, far more Braille labels. (12) In 2006, the French regulatory agency introduced several measures aimed at improving the labelling of ampoules containing some injectable drugs. The impact of these measures was visible on several products marketed in 2006, including plastic vials of solutions for nebulization. (13) Several other examples of well-designed packaging were seen: safety devices on prefilled syringes; a childproof safety device; a tamperproof ring; unit-dose blister packs; clearly written patient leaflets; and the use of clear and appropriate symbols and pictograms. (14) In practice, in view of the large number of incidents recorded in 2006, and the plethora of packaging designs, caregivers should take time to analyse and discuss drug packaging. In this way, they will be in a position to distinguish between good and bad drug packaging, and to anticipate the risks associated with poorly designed packaging. (15) There are many ways in which drug regulatory authorities can help to ensure that drugs are sold in safe packaging. The French regulatory agency's work on the labelling of injectable drugs is an encouraging step. European Directive 2004/27/EC on medicines for human use provides for improvements in labelling (e.g. Braille) and patient information leaflets. Transposition of these measures into French law should lead to a number of improvements, provided the relevant regulations and guidelines place patients' interests first.

Conditioning of the 4 Curies Radium-226 Sealed Radiation Source in Thailand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Punnachaiya, M.; Sawangsri, T.; Wanabongse, P.

This paper describes the conditioning of the 4 curies Radium-226 (Ra-226) sealed radiation source using as a teletherapy unit for cancer treatment in Thailand. The conditioning was under the International Atomic Energy Agency (IAEA) supervision and budgetary supports, comprised of 6 operational steps: the surface dose rate and actual dimension of radium unit measurements, the appropriate lead shielding design with IAEA approval, confirmation of radioactive contamination before conditioning (smear test and radon gas leakage test), transfer of radium source unit into the designed shielding, confirmation of radioactive contamination and dose rate measurement after conditioning, and transportation of Ra-226 conditioning wastemore » package to OAP interim waste storage. The Ra-226 unit was taken out of OAP temporary waste storage for the surface dose rate and the actual dimension measurements behind the 12 inches thick heavy concrete shielding. The maximum measured surface dose rate was 70 R/hr. The special lead container was designed according to its surface dose rate along the source unit which the maximum permissible dose limit for surface dose rate of waste package after conditioning at 2 mSv/hr was applied. The IAEA approved container had total weight of 2.4 ton. After the confirmation of radioactive contamination, Ra-226 source unit was transferred and loaded in the designed lead shielding within 2 minutes. The results of smear test before and after conditioning including radon gas leakage test revealed that there was no radioactive contamination. After conditioning, the surface dose rate measured on the top, bottom were 15,10 mR/hr and varied from 6 - 50 mR/hr around lead container. The Ra-226 conditioning waste package was safely transported to store in OAP interim waste storage. Total working time including the time consumed for radon gas leakage test was 3.5 hours. The total radiation dose received by 16 operators, were ranged from 1 - 69.84 {mu}Sv and the operational team completed the conditioning safely within the effective dose limit for occupational exposure of 50 mSv/year (200 {mu}Sv/day). (authors)« less

A decade of Australian methotrexate dosing errors.

PubMed

Cairns, Rose; Brown, Jared A; Lynch, Ann-Maree; Robinson, Jeff; Wylie, Carol; Buckley, Nicholas A

2016-06-06

Accidental daily dosing of methotrexate can result in life-threatening toxicity. We investigated methotrexate dosing errors reported to the National Coronial Information System (NCIS), the Therapeutic Goods Administration Database of Adverse Event Notifications (TGA DAEN) and Australian Poisons Information Centres (PICs). A retrospective review of coronial cases in the NCIS (2000-2014), and of reports to the TGA DAEN (2004-2014) and Australian PICs (2004-2015). Cases were included if dosing errors were accidental, with evidence of daily dosing on at least 3 consecutive days. Events per year, dose, consecutive days of methotrexate administration, reasons for the error, clinical features. Twenty-two deaths linked with methotrexate were identified in the NCIS, including seven cases in which erroneous daily dosing was documented. Methotrexate medication error was listed in ten cases in the DAEN, including two deaths. Australian PIC databases contained 92 cases, with a worrying increase seen during 2014-2015. Reasons for the errors included patient misunderstanding and incorrect packaging of dosette packs by pharmacists. The recorded clinical effects of daily dosage were consistent with those previously reported for methotrexate toxicity. Dosing errors with methotrexate can be lethal and continue to occur despite a number of safety initiatives in the past decade. Further strategies to reduce these preventable harms need to be implemented and evaluated. Recent suggestions include further changes in packet size, mandatory weekly dosing labelling on packaging, improving education, and including alerts in prescribing and dispensing software.

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA Goddard Space Flight Center and NASA Electronic Parts and Packaging Program

NASA Technical Reports Server (NTRS)

Topper, Alyson D.; Campola, Michael J.; Chen, Dakai; Casey, Megan C.; Yau, Ka-Yen; Cochran, Donna J.; Label, Kenneth A.; Ladbury, Raymond L.; Mondy, Timothy K.; O'Bryan, Martha V.;

Gene expression changes in medical workers exposed to radiation.

PubMed

Morandi, Elena; Severini, Cinzia; Quercioli, Daniele; Perdichizzi, Stefania; Mascolo, Maria Grazia; Horn, Wolfango; Vaccari, Monica; Nucci, Maria Concetta; Lodi, Vittorio; Violante, Francesco Saverio; Bolognesi, Claudia; Grilli, Sandro; Silingardi, Paola; Colacci, Annamaria

2009-10-01

The use of nuclear resources for medical purposes causes considerable concern about occupational exposure. Nevertheless, little information is available regarding the effects of low-dose irradiations protracted over time. We used oligomicroarrays to identify the genes that are transcriptionally regulated by persistent exposure to extremely low doses of ionizing radiation in 28 exposed professionals (mean cumulative effective dose +/- SD, 19 +/- 38 mSv) compared with a matched sample of nonexposed subjects. We identified 256 modulated genes from peripheral blood mononuclear cells profiles, and the main biological processes we found were DNA packaging and mitochondrial electron transport NADH to ubiquinone. Next we investigated whether a different pattern existed when only 22 exposed subjects with accumulated doses >2.5 mSv, a threshold corresponding to the natural background radiation in Italy per year, and mean equal to 25 +/- 41 mSv were used. In addition to DNA packaging and NADH dehydrogenase function, the analysis of the higher-exposed subgroup revealed a significant modulation of ion homeostasis and programmed cell death as well. The changes in gene expression that we found suggest different mechanisms from those involved in high-dose studies that may help to define new biomarkers of radiation exposure for accumulated doses below 25 mSv.

Effects of ionizing radiation on properties of monolayer and multilayer flexible food packaging materials

NASA Astrophysics Data System (ADS)

Riganakos, K. A.; Koller, W. D.; Ehlermann, D. A. E.; Bauer, B.; Kontominas, M. G.

1999-05-01

Volatile compounds produced in flexible food packaging materials (LDPE, EVAc, PET/PE/EVOH/PE) during electron beam irradiation were isolated by purge and trap technique and identified by combined gas chromatography-mass spectrometry (GC/MS), after thermal desorption and concentration. For comparison purposes non-irradiated films were also studied. Film samples were irradiated at low (5 kGy, corresponding to cold pasteurization), intermediate (20 kGy, corresponding to cold sterilization) and high (100 kGy) doses. It was observed that a number of volatile compounds are produced after irradiation in all cases. Furthermore the amounts of all volatile compounds increase with increasing irradiation dose. Both primary (methyl-derivatives etc.) as well as secondary i.e. oxidation products (ketones, aldehydes, alcohols, carboxylic acids etc.) are produced upon irradiation. These products may affect organoleptic properties and thus shelf-life of prepackaged irradiated foods. No significant changes were observed in the structure of polymer matrices as exhibited by IR spectra after irradiation of the materials at doses tested. Likewise, no significant changes were observed in O 2, H 2O and CO 2 permeability values of plastic packaging materials after irradiation.

Quantitative modeling of total ionizing dose reliability effects in device silicon dioxide layers

NASA Astrophysics Data System (ADS)

Rowsey, Nicole L.

The electrical breakdown of oxides and oxide/semiconductor interfaces is one of the main reasons for device failure in integrated circuits, especially devices under high-stress conditions. One high-stress environment of interest is the space environment. All electronics are vulnerable to ionizing radiation; any high-energy particle that passes through an insulating layer will deposit unwanted charge there, causing shifts in device characteristics. Designing electronics for use in space can be a challenge, because much more energetic radiation exits in space than on Earth, as there is no atmosphere in space to collide with, and thereby reduce the energy of, energetic particles. Although oxide charging due to ionizing radiation creates well-known changes in device characteristics, or total ionizing dose effects, it is still poorly-understood exactly how these changes come about. There are many theories that draw upon a large body of both experimental work and, more recently, quantum-mechanical first principles calculations at the molecular level. This work uses FLOODS, a 3D object-oriented device simulator with multi-physics capability, to investigate these theories, by simulating oxide degradation in realistic device geometries, and comparing the subsequent degradation in device characteristics to experimental measurements. The charge trapping and defect-modulated transport models developed and implemented here have resulted in the first quantitative account of the enhanced low-dose-rate sensitivity effect, and are applicable in a comprehensive range of hydrogen environments. Measurements show that devices exposed to ionizing radiation at high dose rates exhibit less degradation that those exposed at low dose rates. Furthermore, the observed trend differs depending on the amount of hydrogen available before, during, and after irradiation. It is therefore important to understand and take into account the effects of dose rate and hydrogen when developing accelerated testing procedures for devices which have been exposed to various levels of hydrogen during processing and packaging, and which must be deployed in the low-dose-rate space environment. Thus, this work represents a substantial increase in the state-of-the-art, since a quantitative model has not previously been available. The success of the model is due in great part to the use of first-principles calculations of defect and hydrogen bond energies. Vanderbilt collaborators provided the results of these calculations as input to the FLOODS simulations. Using these physical insights, a sensitivity analysis in FLOODS yielded insights into key controlling parameters.

A study on the suitability of the PTW microDiamond detector for kilovoltage x-ray beam dosimetry.

PubMed

Damodar, Joshita; Odgers, David; Pope, Dane; Hill, Robin

2018-05-01

Kilovoltage x-ray beams are widely used in treating skin cancers and in biological irradiators. In this work, we have evaluated four dosimeters (ionization chambers and solid state detectors) in their suitability for relative dosimetry of kilovoltage x-ray beams in the energy range of 50 - 280kVp. The solid state detectors, which have not been investigated with low energy x-rays, were the PTW 60019 microDiamond synthetic diamond detector and the PTW 60012 diode. The two ionization chambers used were the PTW Advanced Markus parallel plate chamber and the PTW PinPoint small volume chamber. For each of the dosimeters, percentage depth doses were measured in water over the full range of x-ray beams and for field sizes ranging from 2cm diameter to 12 × 12cm. In addition, depth doses were measured for a narrow aperture (7mm diameter) using the PTW microDiamond detector. For comparison, the measured data was compared with Monte Carlo calculated doses using the EGSnrc Monte Carlo package. The depth dose results indicate that the Advanced Markus parallel plate and PinPoint ionization chambers were suitable for depth dose measurements in the beam quality range with an uncertainty of less than 3%, including in the regions closer to the surface of the water as compared with Monte Carlo depth dose data for all six energy beams. The response of the PTW Diode E detector was accurate to within 4% for all field sizes in the energy range of 50-125kVp but showed larger variations for higher energies of up to 12% with the 12 × 12cm field size. In comparison, the microDiamond detector had good agreement over all energies for both smaller and larger field sizes generally within 1% as compared to the Advanced Markus chamber field and Monte Carlo calculations. The only exceptions were in measuring the dose at the surface of the water phantom where larger differences were found. For the 7mm diameter field, the agreement between the microDiamond detector and Monte Carlo calculations was good being better than 1% except at the surface. Based on these results, the PTW microDiamond detector has shown to be a suitable detector for relative dosimetry of low energy x-ray beams over a wide range of x-ray beam energies. Copyright © 2018 Elsevier Ltd. All rights reserved.

21 CFR 1310.06 - Content of records and reports.

Code of Federal Regulations, 2010 CFR

2010-04-01

... exempted from §§ 1300.02(b)(28)(i)(D) or 1300.02(b)(28)(i)(E) during the preceding calendar year. (6) Data shall identify the specific isomer, salt or ester when applicable but quantitative data shall be....). (9) Number of dosage units (if drug product) (100 doses per package). (10) Package type (if drug...

10 CFR 71.51 - Additional requirements for Type B packages.

Code of Federal Regulations, 2014 CFR

2014-01-01

... sensitivity of 10−6 A2 per hour, no significant increase in external surface radiation levels, and no substantial reduction in the effectiveness of the packaging; and (2) Section 71.73 (“Hypothetical accident... radioactive material exceeding a total amount A2 in 1 week, and no external radiation dose rate exceeding 10 m...

10 CFR 71.51 - Additional requirements for Type B packages.

Code of Federal Regulations, 2012 CFR

2012-01-01

... sensitivity of 10−6 A2 per hour, no significant increase in external surface radiation levels, and no substantial reduction in the effectiveness of the packaging; and (2) Section 71.73 (“Hypothetical accident... radioactive material exceeding a total amount A2 in 1 week, and no external radiation dose rate exceeding 10 m...

10 CFR 71.51 - Additional requirements for Type B packages.

Code of Federal Regulations, 2013 CFR

2013-01-01

... sensitivity of 10−6 A2 per hour, no significant increase in external surface radiation levels, and no substantial reduction in the effectiveness of the packaging; and (2) Section 71.73 (“Hypothetical accident... radioactive material exceeding a total amount A2 in 1 week, and no external radiation dose rate exceeding 10 m...

10 CFR 71.51 - Additional requirements for Type B packages.

Code of Federal Regulations, 2011 CFR

2011-01-01

... sensitivity of 10−6 A2 per hour, no significant increase in external surface radiation levels, and no substantial reduction in the effectiveness of the packaging; and (2) Section 71.73 (“Hypothetical accident... radioactive material exceeding a total amount A2 in 1 week, and no external radiation dose rate exceeding 10 m...

10 CFR 71.51 - Additional requirements for Type B packages.

Code of Federal Regulations, 2010 CFR

2010-01-01

... sensitivity of 10−6 A2 per hour, no significant increase in external surface radiation levels, and no substantial reduction in the effectiveness of the packaging; and (2) Section 71.73 (“Hypothetical accident... radioactive material exceeding a total amount A2 in 1 week, and no external radiation dose rate exceeding 10 m...

Hybrid dose calculation: a dose calculation algorithm for microbeam radiation therapy

NASA Astrophysics Data System (ADS)

Donzelli, Mattia; Bräuer-Krisch, Elke; Oelfke, Uwe; Wilkens, Jan J.; Bartzsch, Stefan

2018-02-01

Microbeam radiation therapy (MRT) is still a preclinical approach in radiation oncology that uses planar micrometre wide beamlets with extremely high peak doses, separated by a few hundred micrometre wide low dose regions. Abundant preclinical evidence demonstrates that MRT spares normal tissue more effectively than conventional radiation therapy, at equivalent tumour control. In order to launch first clinical trials, accurate and efficient dose calculation methods are an inevitable prerequisite. In this work a hybrid dose calculation approach is presented that is based on a combination of Monte Carlo and kernel based dose calculation. In various examples the performance of the algorithm is compared to purely Monte Carlo and purely kernel based dose calculations. The accuracy of the developed algorithm is comparable to conventional pure Monte Carlo calculations. In particular for inhomogeneous materials the hybrid dose calculation algorithm out-performs purely convolution based dose calculation approaches. It is demonstrated that the hybrid algorithm can efficiently calculate even complicated pencil beam and cross firing beam geometries. The required calculation times are substantially lower than for pure Monte Carlo calculations.

DICOM organ dose does not accurately represent calculated dose in mammography

NASA Astrophysics Data System (ADS)

Suleiman, Moayyad E.; Brennan, Patrick C.; McEntee, Mark F.

2016-03-01

This study aims to analyze the agreement between the mean glandular dose estimated by the mammography unit (organ dose) and mean glandular dose calculated using Dance et al published method (calculated dose). Anonymised digital mammograms from 50 BreastScreen NSW centers were downloaded and exposure information required for the calculation of dose was extracted from the DICOM header along with the organ dose estimated by the system. Data from quality assurance annual tests for the included centers were collected and used to calculate the mean glandular dose for each mammogram. Bland-Altman analysis and a two-tailed paired t-test were used to study the agreement between calculated and organ dose and the significance of any differences. A total of 27,869 dose points from 40 centers were included in the study, mean calculated dose and mean organ dose (+/- standard deviation) were 1.47 (+/-0.66) and 1.38 (+/-0.56) mGy respectively. A statistically significant 0.09 mGy bias (t = 69.25; p<0.0001) with 95% limits of agreement between calculated and organ doses ranging from -0.34 and 0.52 were shown by Bland-Altman analysis, which indicates a small yet highly significant difference between the two means. The use of organ dose for dose audits is done at the risk of over or underestimating the calculated dose, hence, further work is needed to identify the causal agents for differences between organ and calculated doses and to generate a correction factor for organ dose.

Estimating age-based antiretroviral therapy costs for HIV-infected children in resource-limited settings based on World Health Organization weight-based dosing recommendations.

PubMed

Doherty, Kathleen; Essajee, Shaffiq; Penazzato, Martina; Holmes, Charles; Resch, Stephen; Ciaranello, Andrea

2014-05-02

Pediatric antiretroviral therapy (ART) has been shown to substantially reduce morbidity and mortality in HIV-infected infants and children. To accurately project program costs, analysts need accurate estimations of antiretroviral drug (ARV) costs for children. However, the costing of pediatric antiretroviral therapy is complicated by weight-based dosing recommendations which change as children grow. We developed a step-by-step methodology for estimating the cost of pediatric ARV regimens for children ages 0-13 years old. The costing approach incorporates weight-based dosing recommendations to provide estimated ARV doses throughout childhood development. Published unit drug costs are then used to calculate average monthly drug costs. We compared our derived monthly ARV costs to published estimates to assess the accuracy of our methodology. The estimates of monthly ARV costs are provided for six commonly used first-line pediatric ARV regimens, considering three possible care scenarios. The costs derived in our analysis for children were fairly comparable to or slightly higher than available published ARV drug or regimen estimates. The methodology described here can be used to provide an accurate estimation of pediatric ARV regimen costs for cost-effectiveness analysts to project the optimum packages of care for HIV-infected children, as well as for program administrators and budget analysts who wish to assess the feasibility of increasing pediatric ART availability in constrained budget environments.

Monte Carlo Shielding Comparative Analysis Applied to TRIGA HEU and LEU Spent Fuel Transport

NASA Astrophysics Data System (ADS)

Margeanu, C. A.; Margeanu, S.; Barbos, D.; Iorgulis, C.

2010-12-01

The paper is a comparative study of LEU and HEU fuel utilization effects for the shielding analysis during spent fuel transport. A comparison against the measured data for HEU spent fuel, available from the last stage of spent fuel repatriation fulfilled in the summer of 2008, is also presented. All geometrical and material data for the shipping cask were considered according to NAC-LWT Cask approved model. The shielding analysis estimates radiation doses to shipping cask wall surface, and in air at 1 m and 2 m, respectively, from the cask, by means of 3D Monte Carlo MORSE-SGC code. Before loading into the shipping cask, TRIGA spent fuel source terms and spent fuel parameters have been obtained by means of ORIGEN-S code. Both codes are included in ORNL's SCALE 5 programs package. The actinides contribution to total fuel radioactivity is very low in HEU spent fuel case, becoming 10 times greater in LEU spent fuel case. Dose rates for both HEU and LEU fuel contents are below regulatory limits, LEU spent fuel photon dose rates being greater than HEU ones. Comparison between HEU spent fuel theoretical and measured dose rates in selected measuring points shows a good agreement, calculated values being greater than the measured ones both to cask wall surface (about 34% relative difference) and in air at 1 m distance from cask surface (about 15% relative difference).

The Next Generation in Subsidence and Aquifer-System Compaction Modeling within the MODFLOW Software Family: A New Package for MODFLOW-2005 and MODFLOW-OWHM

NASA Astrophysics Data System (ADS)

Boyce, S. E.; Leake, S. A.; Hanson, R. T.; Galloway, D. L.

2015-12-01

The Subsidence and Aquifer-System Compaction Packages, SUB and SUB-WT, for MODFLOW are two currently supported subsidence packages within the MODFLOW family of software. The SUB package allows the calculation of instantaneous and delayed releases of water from distributed interbeds (relatively more compressible fine-grained sediments) within a saturated aquifer system or discrete confining beds. The SUB-WT package does not include delayed releases, but does perform a more rigorous calculation of vertical stresses that can vary the effective stress that causes compaction. This calculation of instantaneous compaction can include the effect of water-table fluctuations for unconfined aquifers on effective stress, and can optionally adjust the elastic and inelastic storage properties based on the changes in effective stress. The next generation of subsidence modeling in MODFLOW is under development, and will merge and enhance the capabilities of the SUB and SUB-WT Packages for MODFLOW-2005 and MODFLOW-OWHM. This new version will also provide some additional features such as stress dependent vertical hydraulic conductivity of interbeds, time-varying geostatic loads, and additional attributes related to aquifer-system compaction and subsidence that will broaden the class of problems that can be simulated. The new version will include a redesigned source code, a new user friendly input file structure, more output options, and new subsidence solution options. This presentation will discuss progress in developing the new package and the new features being implemented and their potential applications. By Stanley Leake, Scott E. Boyce, Randall T. Hanson, and Devin Galloway

A Report of the Joint Development of a Prototype Communications Link to Share Nuclear Accident Dispersion and Dose Assessment Modeling Products Between JAERI/WSPEEDI and LLNL/NARAC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, T J; Belles, R D; Ellis, J S

2001-05-01

In June of 1997, under an umbrella Memorandum of Understanding between the Japan Atomic Energy Research Institute (JAERI) and the U.S. Department of Energy (US/DOE) concerning matters of nuclear research and development, a Specific Memorandum of Agreement (SMA) entitled ''A Collaborative Programme of Development of a Prototype Communication Link to Share Atmospheric Dispersion and Dose Assessment Modelling Products'' was signed. This SMA formalized an informal collaborative exchange between the DOE's Lawrence Livermore National Laboratory (LLNL) Atmospheric Release Advisory Capability (ARAC) center and the Japan Atomic Energy Research Institute (JAERI) Worldwide System for Prediction of Environmental Emergency Dose Information (WSPEEDI). Themore » intended objective of this agreement was to explore various modes of information exchange, beyond facsimile transmission, which could provide for the quick exchange of information between two major nuclear emergency dose assessment and prediction national centers to provide consistency checks and data exchange before public release of their calculations. The extreme sensitivity of the general public to any nuclear accident information has been a strong motivation to seek peer preview prior to public release. Other intended objectives of this work are the development of an affordable/accessible system for distribution of prediction results to other countries having no prediction capabilities and utilization of the link for collaboration studies. To fulfill the objectives of this project JAERI and LLNL scientists determined to assess the evolving Internet and rapidly emerging communications application software. Our timing was a little early in 1997-1998 but nonetheless a few candidate software packages were found, evaluated and a selection was made for initial test and evaluation. Subsequently several new candidate software packages have arrived, albeit with limitations. This report outlines the ARAC and JAERI emergency response assessment systems, describes the prototype communications protocol system established and the tools evaluated in that process. Three real-time applications of the information exchange protocol and lessons learned are discussed and then some conclusions and future plans are presented.« less

Thick photosensitive polyimide film side wall angle variability and scum improvement for IC packaging stress control

NASA Astrophysics Data System (ADS)

Mehta, Sohan Singh; Yeung, Marco; Mirza, Fahad; Raman, Thiagarajan; Longenbach, Travis; Morgan, Justin; Duggan, Mark; Soedibyo, Rio A.; Reidy, Sean; Rabie, Mohamed; Cho, Jae Kyu; Premachandran, C. S.; Faruqui, Danish

2018-03-01

In this paper, we demonstrate photosensitive polyimide (PSPI) profile optimization to effectively reduce stress concentrations and enable PSPI as protection package-induced stress. Through detailed package simulation, we demonstrate 45% reduction in stress as the sidewall angle (SWA) of PSPI is increased from 45 to 80 degrees in Cu pillar package types. Through modulation of coating and develop multi-step baking temperature and time, as well as dose energy and post litho surface treatments, we demonstrate a method for reliably obtaining PSPI sidewall angle >75 degree. Additionally, we experimentally validate the simulation findings that PSPI sidewall angle impacts chip package interaction (CPI). Finally, we conclude this paper with PSPI material and tool qualification requirements for future technology node based on current challenges.

Poster — Thur Eve — 28: Enabling trajectory-based radiotherapy on a TrueBeam accelerator with the Eclipse treatment planning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullins, J; Asiev, K; DeBlois, F

2014-08-15

The TrueBeam linear accelerator platform has a developer's mode which permits the user dynamic control over many of the machine's mechanical and radiation systems. Using this research tool, synchronous couch and gantry motion can be programmed to simulate isocentric treatment with a shortened SAD, with benefits such as smaller projected MLC leaf widths and an increased dose rate. In this work, water tank measurements were used to commission a virtual linear accelerator with an 85 cm SAD in Eclipse, from which several arc-based radiotherapy treatments were generated, including an inverse optimized VMAT delivery. For each plan, the pertinent treatment deliverymore » information was extracted from control points specified in the Eclipse-exported DICOM files using the pydicom package in Python, allowing construction of an XML control file. The dimensions of the jaws and MLC positions, defined for an 85 cm SAD in Eclipse, were scaled for delivery on a conventional SAD linear accelerator, and translational couch motion was added as a function of gantry angle to simulate delivery at 85 cm SAD. Ionization chamber and Gafchromic film measurements were used to compare the radiation delivery to dose calculations in Eclipse. With the exception of the VMAT delivery, ionization chamber measurements agreed within 3.3% of the Eclipse calculations. For the VMAT delivery, the ionization chamber was located in an inhomogeneous region, but gamma evaluation of the Gafchromic film plane resulted in a 94.5% passing rate using criteria of 3 mm/3%. The results indicate that Eclipse calculation infrastructure can be used.« less

Effect of modified atmosphere packaging and irradiation in combination on content of nitrosamines in cooked pork sausage.

PubMed

Song, I H; Kim, W J; Jo, C; Ahn, H J; Kim, J H; Byun, M W

2003-06-01

The effect of modified atmosphere packaging and irradiation in combination on nitrosodimethylamine (NDMA) and nitrosopyrrolidine (NPYR) levels in pork sausage was studied. Emulsion-type cooked pork sausage was manufactured and packaged in aerobic, CO2 (100%), N2 (100%), and CO2/N2 (25%/75%) environments, respectively, and irradiated at 0, 5, 10, and 20 kGy with gamma irradiation. The nitrosamine contents were significantly reduced by irradiation, and the reduction of nitrosamines was more extensive with modified atmosphere packaging than with aerobic packaging. The correlation coefficient between irradiation dose and nitrosamine content indicated that irradiation can reduce the levels of nitrosamines. The combination of irradiation and modified atmosphere packaging is effective in enhancing the chemical safety of sausage by reducing nitrosamines, if present, as well as enhancing the microbial safety of cooked pork sausage.

Radiation measurements aboard the fourth Gemini flight.

PubMed

Janni, J F; Schneider, M F

1967-01-01

Two special tissue-equivalent ionization chambers and 5 highly sensitive passive dosimetry packages were flown aboard the recent Gemini 4 flight for the purpose of obtaining precise values of instantaneous dose rate, accumulated dose. and shielding effectiveness. This experiment marked the first time that well-defined tissue dose and radiation survey measurements have been carried out in manned spaceflight operations. Since all measurements were accomplished under normal spacecraft environmental conditions, the biological dose resulted primarily from trapped inner Van Allen Belt radiation encountered by the spacecraft in the South Atlantic Anomaly. The experiment determined the particle type, ionizing and penetrating power, and variation with time and position within the Gemini spacecraft. Measured dose rates ranged from 100 mrad/hr for passes penetrating deeply into the South Atlantic Anomaly to less than 0.1 mrad/hr from lower latitude cosmic radiation. The accumulated tissue dose measured by the active ionization chambers, shielded by 0.4 gm/cm2 for the 4-day mission, was 82 mrad. Since the 5 passive dosimetry packages were each located in different positions within the spacecraft, the total mission surface dose measured by these detectors varied from 73 to 27 mrad, depending upon location and shielding. The particles within the spacecraft were recorded in nuclear emulsion, which established that over 90% of the tissue dose was attributable to penetrating protons. This experiment indicates that the radiation environment under shielded conditions at Gemini altitudes was not hazardous.

Measuring trends of outpatient antibiotic use in Europe: jointly modelling longitudinal data in defined daily doses and packages.

PubMed

Bruyndonckx, Robin; Hens, Niel; Aerts, Marc; Goossens, Herman; Molenberghs, Geert; Coenen, Samuel

2014-07-01

To complement analyses of the linear trend and seasonal fluctuation of European outpatient antibiotic use expressed in defined daily doses (DDD) by analyses of data in packages, to assess the agreement between both measures and to study changes in the number of DDD per package over time. Data on outpatient antibiotic use, aggregated at the level of the active substance (WHO version 2011) were collected from 2000 to 2007 for 31 countries and expressed in DDD and packages per 1000 inhabitants per day (DID and PID, respectively). Data expressed in DID and PID were analysed separately using non-linear mixed models while the agreement between these measurements was analysed through a joint non-linear mixed model. The change in DDD per package over time was studied with a linear mixed model. Total outpatient antibiotic and penicillin use in Europe and their seasonal fluctuation significantly increased in DID, but not in PID. The use of combinations of penicillins significantly increased in DID and in PID. Broad-spectrum penicillin use did not increase significantly in DID and decreased significantly in PID. For all but one subgroup, country-specific deviations moved in the same direction whether measured in DID or PID. The correlations are not perfect. The DDD per package increased significantly over time for all but one subgroup. Outpatient antibiotic use in Europe shows contrasting trends, depending on whether DID or PID is used as the measure. The increase of the DDD per package corroborates the recommendation to adopt PID to monitor outpatient antibiotic use in Europe. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Software and package applicating for network meta-analysis: A usage-based comparative study.

PubMed

Xu, Chang; Niu, Yuming; Wu, Junyi; Gu, Huiyun; Zhang, Chao

2017-12-21

To compare and analyze the characteristics and functions of software applications for network meta-analysis (NMA). PubMed, EMbase, The Cochrane Library, the official websites of Bayesian inference Using Gibbs Sampling (BUGS), Stata and R, and Google were searched to collect the software and packages for performing NMA; software and packages published up to March 2016 were included. After collecting the software, packages, and their user guides, we used the software and packages to calculate a typical example. All characteristics, functions, and computed results were compared and analyzed. Ten types of software were included, including programming and non-programming software. They were developed mainly based on Bayesian or frequentist theory. Most types of software have the characteristics of easy operation, easy mastery, exact calculation, or excellent graphing. However, there was no single software that performed accurate calculations with superior graphing; this could only be achieved through the combination of two or more types of software. This study suggests that the user should choose the appropriate software according to personal programming basis, operational habits, and financial ability. Then, the choice of the combination of BUGS and R (or Stata) software to perform the NMA is considered. © 2017 Chinese Cochrane Center, West China Hospital of Sichuan University and John Wiley & Sons Australia, Ltd.

The physical and chemical stability of anti-tuberculosis fixed-dose combination products under accelerated climatic conditions.

PubMed

Bhutani, H; Mariappan, T T; Singh, S

2004-09-01

To determine the physical and chemical stability of anti-tuberculosis fixed-dose combinations (FDC) of rifampicin (RMP), isoniazid (INH), pyrazinamide (PZA) and ethambutol (EMB) sold on the Indian market. The products were stored for 3 months under ICH/WHO accelerated conditions (40 degrees C / 75% RH), with and without the original packaging in the presence and absence of light. The initial RMP, INH and PZA content was found to be within the range of 90-110% of the label claim. However, the products were found to have some chemical instability even initially; one of the tablets also showed physical instability. Under accelerated conditions, the unpackaged products underwent severe changes, whereas both physical and chemical changes were also observed in the packaged formulations. The physical changes were stronger under lighted conditions. A significant finding is that PZA and perhaps EMB may play a catalytic role in the interaction between INH and RMP. This study suggests that, unless they are packed in barrier packaging, anti-tuberculosis FDC formulations should be considered unstable, and due consideration should be given to their development pharmaceutics, packaging and stability testing.

The accuracy of the out-of-field dose calculations using a model based algorithm in a commercial treatment planning system

NASA Astrophysics Data System (ADS)

Wang, Lilie; Ding, George X.

2014-07-01

The out-of-field dose can be clinically important as it relates to the dose of the organ-at-risk, although the accuracy of its calculation in commercial radiotherapy treatment planning systems (TPSs) receives less attention. This study evaluates the uncertainties of out-of-field dose calculated with a model based dose calculation algorithm, anisotropic analytical algorithm (AAA), implemented in a commercial radiotherapy TPS, Varian Eclipse V10, by using Monte Carlo (MC) simulations, in which the entire accelerator head is modeled including the multi-leaf collimators. The MC calculated out-of-field doses were validated by experimental measurements. The dose calculations were performed in a water phantom as well as CT based patient geometries and both static and highly modulated intensity-modulated radiation therapy (IMRT) fields were evaluated. We compared the calculated out-of-field doses, defined as lower than 5% of the prescription dose, in four H&N cancer patients and two lung cancer patients treated with volumetric modulated arc therapy (VMAT) and IMRT techniques. The results show that the discrepancy of calculated out-of-field dose profiles between AAA and the MC depends on the depth and is generally less than 1% for in water phantom comparisons and in CT based patient dose calculations for static field and IMRT. In cases of VMAT plans, the difference between AAA and MC is <0.5%. The clinical impact resulting from the error on the calculated organ doses were analyzed by using dose-volume histograms. Although the AAA algorithm significantly underestimated the out-of-field doses, the clinical impact on the calculated organ doses in out-of-field regions may not be significant in practice due to very low out-of-field doses relative to the target dose.

QmeQ 1.0: An open-source Python package for calculations of transport through quantum dot devices

NASA Astrophysics Data System (ADS)

Kiršanskas, Gediminas; Pedersen, Jonas Nyvold; Karlström, Olov; Leijnse, Martin; Wacker, Andreas

2017-12-01

QmeQ is an open-source Python package for numerical modeling of transport through quantum dot devices with strong electron-electron interactions using various approximate master equation approaches. The package provides a framework for calculating stationary particle or energy currents driven by differences in chemical potentials or temperatures between the leads which are tunnel coupled to the quantum dots. The electronic structures of the quantum dots are described by their single-particle states and the Coulomb matrix elements between the states. When transport is treated perturbatively to lowest order in the tunneling couplings, the possible approaches are Pauli (classical), first-order Redfield, and first-order von Neumann master equations, and a particular form of the Lindblad equation. When all processes involving two-particle excitations in the leads are of interest, the second-order von Neumann approach can be applied. All these approaches are implemented in QmeQ. We here give an overview of the basic structure of the package, give examples of transport calculations, and outline the range of applicability of the different approximate approaches.

red - an R package to facilitate species red list assessments according to the IUCN criteria

PubMed Central

2017-01-01

Abstract The International Union for the Conservation of Nature Red List is the most useful database of species that are at risk of extinction worldwide, as it relies on a number of objective criteria and is now widely adopted. The R package red – IUCN Redlisting Tools - performs a number of spatial analyses based on either observed occurrences or estimated ranges. Functions include calculating Extent of Occurrence (EOO), Area of Occupancy (AOO), mapping species ranges, species distribution modelling using climate and land cover and calculating the Red List Index for groups of species. The package allows the calculation of confidence limits for all measures. Spatial data of species occurrences, environmental or land cover variables can be either given by the user or automatically extracted from several online databases. It outputs geographical range, elevation and country values, maps in several formats and vectorial data for visualization in Google Earth. Several examples are shown demonstrating the usefulness of the different methods. The red package constitutes an open platform for further development of new tools to facilitate red list assessments. PMID:29104439

Quantitative assessment of the accuracy of dose calculation using pencil beam and Monte Carlo algorithms and requirements for clinical quality assurance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Imad, E-mail: iali@ouhsc.edu; Ahmad, Salahuddin

2013-10-01

To compare the doses calculated using the BrainLAB pencil beam (PB) and Monte Carlo (MC) algorithms for tumors located in various sites including the lung and evaluate quality assurance procedures required for the verification of the accuracy of dose calculation. The dose-calculation accuracy of PB and MC was also assessed quantitatively with measurement using ionization chamber and Gafchromic films placed in solid water and heterogeneous phantoms. The dose was calculated using PB convolution and MC algorithms in the iPlan treatment planning system from BrainLAB. The dose calculation was performed on the patient's computed tomography images with lesions in various treatmentmore » sites including 5 lungs, 5 prostates, 4 brains, 2 head and necks, and 2 paraspinal tissues. A combination of conventional, conformal, and intensity-modulated radiation therapy plans was used in dose calculation. The leaf sequence from intensity-modulated radiation therapy plans or beam shapes from conformal plans and monitor units and other planning parameters calculated by the PB were identical for calculating dose with MC. Heterogeneity correction was considered in both PB and MC dose calculations. Dose-volume parameters such as V95 (volume covered by 95% of prescription dose), dose distributions, and gamma analysis were used to evaluate the calculated dose by PB and MC. The measured doses by ionization chamber and EBT GAFCHROMIC film in solid water and heterogeneous phantoms were used to quantitatively asses the accuracy of dose calculated by PB and MC. The dose-volume histograms and dose distributions calculated by PB and MC in the brain, prostate, paraspinal, and head and neck were in good agreement with one another (within 5%) and provided acceptable planning target volume coverage. However, dose distributions of the patients with lung cancer had large discrepancies. For a plan optimized with PB, the dose coverage was shown as clinically acceptable, whereas in reality, the MC showed a systematic lack of dose coverage. The dose calculated by PB for lung tumors was overestimated by up to 40%. An interesting feature that was observed is that despite large discrepancies in dose-volume histogram coverage of the planning target volume between PB and MC, the point doses at the isocenter (center of the lesions) calculated by both algorithms were within 7% even for lung cases. The dose distributions measured with EBT GAFCHROMIC films in heterogeneous phantoms showed large discrepancies of nearly 15% lower than PB at interfaces between heterogeneous media, where these lower doses measured by the film were in agreement with those by MC. The doses (V95) calculated by MC and PB agreed within 5% for treatment sites with small tissue heterogeneities such as the prostate, brain, head and neck, and paraspinal tumors. Considerable discrepancies, up to 40%, were observed in the dose-volume coverage between MC and PB in lung tumors, which may affect clinical outcomes. The discrepancies between MC and PB increased for 15 MV compared with 6 MV indicating the importance of implementation of accurate clinical treatment planning such as MC. The comparison of point doses is not representative of the discrepancies in dose coverage and might be misleading in evaluating the accuracy of dose calculation between PB and MC. Thus, the clinical quality assurance procedures required to verify the accuracy of dose calculation using PB and MC need to consider measurements of 2- and 3-dimensional dose distributions rather than a single point measurement using heterogeneous phantoms instead of homogenous water-equivalent phantoms.« less

QMCPACK : an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids

DOE PAGES

Kim, Jeongnim; Baczewski, Andrew T.; Beaudet, Todd D.; ...

2018-04-19

QMCPACK is an open source quantum Monte Carlo package for ab-initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater-Jastrow type trial wave functions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performancemore » computing architectures, including multicore central processing unit (CPU) and graphical processing unit (GPU) systems. We detail the program’s capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://www.qmcpack.org.« less

QMCPACK : an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jeongnim; Baczewski, Andrew T.; Beaudet, Todd D.

QMCPACK is an open source quantum Monte Carlo package for ab-initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater-Jastrow type trial wave functions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performancemore » computing architectures, including multicore central processing unit (CPU) and graphical processing unit (GPU) systems. We detail the program’s capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://www.qmcpack.org.« less

Variation in commercial smoking mixtures containing third-generation synthetic cannabinoids.

PubMed

Frinculescu, Anca; Lyall, Catherine L; Ramsey, John; Miserez, Bram

2017-02-01

Variation in ingredients (qualitative variation) and in quantity of active compounds (quantitative variation) in herbal smoking mixtures containing synthetic cannabinoids has been shown for older products. This can be dangerous to the user, as accurate and reproducible dosing is impossible. In this study, 69 packages containing third-generation cannabinoids of seven brands on the UK market in 2014 were analyzed both qualitatively and quantitatively for variation. When comparing the labels to actual active ingredients identified in the sample, only one brand was shown to be correctly labelled. The other six brands contained less, more, or ingredients other than those listed on the label. Only two brands were inconsistent, containing different active ingredients in different samples. Quantitative variation was assessed both within one package and between several packages. Within-package variation was within a 10% range for five of the seven brands, but two brands showed larger variation, up to 25% (Relative Standard Deviation). Variation between packages was significantly higher, with variation up to 38% and maximum concentration up to 2.7 times higher than the minimum concentration. Both qualitative and quantitative variation are common in smoking mixtures and endanger the user, as it is impossible to estimate the dose or to know the compound consumed when smoking commercial mixtures. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The influence of the dose calculation resolution of VMAT plans on the calculated dose for eye lens and optic pathway.

PubMed

Park, Jong Min; Park, So-Yeon; Kim, Jung-In; Carlson, Joel; Kim, Jin Ho

2017-03-01

To investigate the effect of dose calculation grid on calculated dose-volumetric parameters for eye lenses and optic pathways. A total of 30 patients treated using the volumetric modulated arc therapy (VMAT) technique, were retrospectively selected. For each patient, dose distributions were calculated with calculation grids ranging from 1 to 5 mm at 1 mm intervals. Identical structures were used for VMAT planning. The changes in dose-volumetric parameters according to the size of the calculation grid were investigated. Compared to dose calculation with 1 mm grid, the maximum doses to the eye lens with calculation grids of 2, 3, 4 and 5 mm increased by 0.2 ± 0.2 Gy, 0.5 ± 0.5 Gy, 0.9 ± 0.8 Gy and 1.7 ± 1.5 Gy on average, respectively. The Spearman's correlation coefficient between dose gradients near structures vs. the differences between the calculated doses with 1 mm grid and those with 5 mm grid, were 0.380 (p < 0.001). For the accurate calculation of dose distributions, as well as efficiency, using a grid size of 2 mm appears to be the most appropriate choice.

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA Goddard Space Flight Center and Selected NASA Electronic Parts and Packaging Program

NASA Technical Reports Server (NTRS)

Topper, Alyson D.; Campola, Michael J.; Chen, Dakai; Casey, Megan C.; Yau, Ka-Yen; Cochran, Donna J.; LaBel, Kenneth A.; Ladbury, Raymond L.; Lauenstein, Jean-Marie; Mondy, Timothy K.;

Rindsel: an R package for phenotypic and molecular selection indices used in plant breeding.

PubMed

Perez-Elizalde, Sergío; Cerón-Rojas, Jesús J; Crossa, José; Fleury, Delphine; Alvarado, Gregorio

2014-01-01

Selection indices are estimates of the net genetic merit of the individual candidates for selection and are calculated based on phenotyping and molecular marker information collected on plants under selection in a breeding program. They reflect the breeding value of the plants and help breeders to choose the best ones for next generation. Rindsel is an R package that calculates phenotypic and molecular selection indices.

Poster — Thur Eve — 61: A new framework for MPERT plan optimization using MC-DAO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, M; Lloyd, S AM; Townson, R

2014-08-15

This work combines the inverse planning technique known as Direct Aperture Optimization (DAO) with Intensity Modulated Radiation Therapy (IMRT) and combined electron and photon therapy plans. In particular, determining conditions under which Modulated Photon/Electron Radiation Therapy (MPERT) produces better dose conformality and sparing of organs at risk than traditional IMRT plans is central to the project. Presented here are the materials and methods used to generate and manipulate the DAO procedure. Included is the introduction of a powerful Java-based toolkit, the Aperture-based Monte Carlo (MC) MPERT Optimizer (AMMO), that serves as a framework for optimization and provides streamlined access tomore » underlying particle transport packages. Comparison of the toolkit's dose calculations to those produced by the Eclipse TPS and the demonstration of a preliminary optimization are presented as first benchmarks. Excellent agreement is illustrated between the Eclipse TPS and AMMO for a 6MV photon field. The results of a simple optimization shows the functioning of the optimization framework, while significant research remains to characterize appropriate constraints.« less

The acute lethal dose 50 (LD50) of caffeine in albino rats.

PubMed

Adamson, Richard H

2016-10-01

An acute LD50 is a statistically derived amount of a substance that can be expected to cause death in 50% of the animals when given by a specified route as a single dose and the animals observed for a specified time period. Although conducting routine acute toxicity testing in rodents has been criticized, it can serve useful functions and also have practical implications. Material safety data sheets (MSDS) will reflect the acute toxicity of a substance and may require workers to wear protective gear, if appropriate, based on the LD50. There is no information in the scientific published literature which calculates a mean LD50 and standard deviation for caffeine administered orally to rats, using studies performed under good laboratory practice (GLP) or equivalent. This report does that and should be useful to manufacturers, packagers, transporters and regulators of this material. Using data from studies that are reproducible and reliable, the most accurate estimate of the acute LD50 of caffeine administered orally in male albino rats is hereby reported to be 367/mg/kg. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of radiolysis products in gamma-irradiated multilayer barrier food packaging films containing a middle layer of recycled LDPE

NASA Astrophysics Data System (ADS)

Chytiri, Stavroula; Goulas, Antonios E.; Badeka, Anastasia; Riganakos, Kyriakos A.; Petridis, Dimitrios; Kontominas, Michael G.

2008-09-01

Volatile and non-volatile radiolysis products and sensory changes of five-layer food packaging films have been determined after gamma irradiation (5-60 kGy). Barrier films were based on polyamide (PA) and low-density polyethylene (LDPE). Each film contained a middle buried layer of recycled LDPE or 100% virgin LDPE (control samples). Data showed that a large number of radiolysis products were produced such as hydrocarbons, alcohols, carbonyl compounds, carboxylic acid. These compounds were detected in the food simulant after contact with all films even at the lower absorbed doses of 5 and 10 kGy. The type and concentration of radiolysis products increased progressively with radiation dose, while no new compounds were detected as a result of the presence of recycled LDPE. In addition, irradiation dose appears to influence the sensory properties of table water in contact with films.

Effect of gamma irradiation under various atmospheres of packaging on the microbial and physicochemical properties of turmeric powder

NASA Astrophysics Data System (ADS)

Esmaeili, Saeideh; Barzegar, Mohsen; Sahari, Mohammad Ali; Berengi-Ardestani, Samira

2018-07-01

This study investigated the effect of gamma irradiation (0, 5, 10, and 15 kGy) under various atmospheres of packaging (air, N₂, and vacuum) on the microbial load and physicochemical properties of turmeric powder, including antioxidant activities, total phenolic content (TPC), color parameters, and curcuminoid content. The efficiency of irradiation in reducing microbial contamination in the samples was observed even at the lowest dose. By increasing the irradiation dose, the microbial load was not detectable. Irradiation in the presence of oxygen had synergistic effects on the extraction of curcuminoids and TPC, and increased the antioxidant activity of the methanolic extracts: highest activity was observed at 15 kGy. Generally, gamma irradiation up to the dose of 10 kGy under air atmosphere not only ensured microbial safety and desirability of turmeric powder, but also improved the extraction yield of bioactive compounds and, consequently, antioxidant activities of the samples.

SU-E-T-374: Evaluation and Verification of Dose Calculation Accuracy with Different Dose Grid Sizes for Intracranial Stereotactic Radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, C; Schultheiss, T

Purpose: In this study, we aim to evaluate the effect of dose grid size on the accuracy of calculated dose for small lesions in intracranial stereotactic radiosurgery (SRS), and to verify dose calculation accuracy with radiochromic film dosimetry. Methods: 15 intracranial lesions from previous SRS patients were retrospectively selected for this study. The planning target volume (PTV) ranged from 0.17 to 2.3 cm{sup 3}. A commercial treatment planning system was used to generate SRS plans using the volumetric modulated arc therapy (VMAT) technique using two arc fields. Two convolution-superposition-based dose calculation algorithms (Anisotropic Analytical Algorithm and Acuros XB algorithm) weremore » used to calculate volume dose distribution with dose grid size ranging from 1 mm to 3 mm with 0.5 mm step size. First, while the plan monitor units (MU) were kept constant, PTV dose variations were analyzed. Second, with 95% of the PTV covered by the prescription dose, variations of the plan MUs as a function of dose grid size were analyzed. Radiochomic films were used to compare the delivered dose and profile with the calculated dose distribution with different dose grid sizes. Results: The dose to the PTV, in terms of the mean dose, maximum, and minimum dose, showed steady decrease with increasing dose grid size using both algorithms. With 95% of the PTV covered by the prescription dose, the total MU increased with increasing dose grid size in most of the plans. Radiochromic film measurements showed better agreement with dose distributions calculated with 1-mm dose grid size. Conclusion: Dose grid size has significant impact on calculated dose distribution in intracranial SRS treatment planning with small target volumes. Using the default dose grid size could lead to under-estimation of delivered dose. A small dose grid size should be used to ensure calculation accuracy and agreement with QA measurements.« less

Constructing an Employee Benefit Package for Part-Time Workers. A Rationale for Arriving at an Equitable Benefit Package at No Extra Cost to the Employer. A Catalyst Position Paper.

ERIC Educational Resources Information Center

Catalyst, New York, NY.

Guidelines are presented for constructing an employee benefit package for part-time workers in which benefits are calculated on a pro-rated (and sometimes selective) basis, such that part-time employees receive a fair proportion of the total benefit package, based on the number of hours they actually work. Pro-rating is recommended as feasible for…

Nondestructive determination of activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chabalier, B.

1996-08-01

Characterization and appraisal tests include the measurement of activity in raw waste and waste packages. After conditioning, variations in density, matrix composition, and geometry make evaluation of the radionuclide activity in a package destined for storage nearly impossible without measurements and with a low uncertainty. Various nondestructive measuring techniques that use ionizing radiation are employed to characterize waste packages and raw waste. Gamma spectrometry is the most widely used technique because of its simple operation and low cost. This technique is used to quantify the beta-gamma and alpha activity of gamma-emitting radionuclides as well as to check the radioactive homogeneitymore » of the waste packages. Numerous systems for directly measuring waste packages have been developed. Two types of methods may be distinguished, depending on whether results that come from the measurements are weighted by an experimentally determined corrective term or by calculation. Through the MARCO and CARACO measuring systems, a method is described that allows one to quantify the activity of the beta-gamma and alpha radionuclides contained in either a waste package or raw waste whose geometries and material compositions are more or less accurately known. This method is based on (a) measurement by gamma spectrometry of the beta-gamma and alpha activity of the gamma-emitting radionuclides contained in the waste package and (b) the application of calculated corrections; thus, the limitations imposed by reference package geometry and matrix are avoided.« less

Analysis of outcomes in radiation oncology: An integrated computational platform

PubMed Central

Liu, Dezhi; Ajlouni, Munther; Jin, Jian-Yue; Ryu, Samuel; Siddiqui, Farzan; Patel, Anushka; Movsas, Benjamin; Chetty, Indrin J.

2009-01-01

Radiotherapy research and outcome analyses are essential for evaluating new methods of radiation delivery and for assessing the benefits of a given technology on locoregional control and overall survival. In this article, a computational platform is presented to facilitate radiotherapy research and outcome studies in radiation oncology. This computational platform consists of (1) an infrastructural database that stores patient diagnosis, IMRT treatment details, and follow-up information, (2) an interface tool that is used to import and export IMRT plans in DICOM RT and AAPM/RTOG formats from a wide range of planning systems to facilitate reproducible research, (3) a graphical data analysis and programming tool that visualizes all aspects of an IMRT plan including dose, contour, and image data to aid the analysis of treatment plans, and (4) a software package that calculates radiobiological models to evaluate IMRT treatment plans. Given the limited number of general-purpose computational environments for radiotherapy research and outcome studies, this computational platform represents a powerful and convenient tool that is well suited for analyzing dose distributions biologically and correlating them with the delivered radiation dose distributions and other patient-related clinical factors. In addition the database is web-based and accessible by multiple users, facilitating its convenient application and use. PMID:19544785

SU-F-T-441: Dose Calculation Accuracy in CT Images Reconstructed with Artifact Reduction Algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, C; Chan, S; Lee, F

Purpose: Accuracy of radiotherapy dose calculation in patients with surgical implants is complicated by two factors. First is the accuracy of CT number, second is the dose calculation accuracy. We compared measured dose with dose calculated on CT images reconstructed with FBP and an artifact reduction algorithm (OMAR, Philips) for a phantom with high density inserts. Dose calculation were done with Varian AAA and AcurosXB. Methods: A phantom was constructed with solid water in which 2 titanium or stainless steel rods could be inserted. The phantom was scanned with the Philips Brillance Big Bore CT. Image reconstruction was done withmore » FBP and OMAR. Two 6 MV single field photon plans were constructed for each phantom. Radiochromic films were placed at different locations to measure the dose deposited. One plan has normal incidence on the titanium/steel rods. In the second plan, the beam is at almost glancing incidence on the metal rods. Measurements were then compared with dose calculated with AAA and AcurosXB. Results: The use of OMAR images slightly improved the dose calculation accuracy. The agreement between measured and calculated dose was best with AXB and image reconstructed with OMAR. Dose calculated on titanium phantom has better agreement with measurement. Large discrepancies were seen at points directly above and below the high density inserts. Both AAA and AXB underestimated the dose directly above the metal surface, while overestimated the dose below the metal surface. Doses measured downstream of metal were all within 3% of calculated values. Conclusion: When doing treatment planning for patients with metal implants, care must be taken to acquire correct CT images to improve dose calculation accuracy. Moreover, great discrepancies in measured and calculated dose were observed at metal/tissue interface. Care must be taken in estimating the dose in critical structures that come into contact with metals.« less

Variations in algorithm implementation among quantitative texture analysis software packages

NASA Astrophysics Data System (ADS)

Foy, Joseph J.; Mitta, Prerana; Nowosatka, Lauren R.; Mendel, Kayla R.; Li, Hui; Giger, Maryellen L.; Al-Hallaq, Hania; Armato, Samuel G.

2018-02-01

Open-source texture analysis software allows for the advancement of radiomics research. Variations in texture features, however, result from discrepancies in algorithm implementation. Anatomically matched regions of interest (ROIs) that captured normal breast parenchyma were placed in the magnetic resonance images (MRI) of 20 patients at two time points. Six first-order features and six gray-level co-occurrence matrix (GLCM) features were calculated for each ROI using four texture analysis packages. Features were extracted using package-specific default GLCM parameters and using GLCM parameters modified to yield the greatest consistency among packages. Relative change in the value of each feature between time points was calculated for each ROI. Distributions of relative feature value differences were compared across packages. Absolute agreement among feature values was quantified by the intra-class correlation coefficient. Among first-order features, significant differences were found for max, range, and mean, and only kurtosis showed poor agreement. All six second-order features showed significant differences using package-specific default GLCM parameters, and five second-order features showed poor agreement; with modified GLCM parameters, no significant differences among second-order features were found, and all second-order features showed poor agreement. While relative texture change discrepancies existed across packages, these differences were not significant when consistent parameters were used.

Dose specification for radiation therapy: dose to water or dose to medium?

NASA Astrophysics Data System (ADS)

Ma, C.-M.; Li, Jinsheng

2011-05-01

The Monte Carlo method enables accurate dose calculation for radiation therapy treatment planning and has been implemented in some commercial treatment planning systems. Unlike conventional dose calculation algorithms that provide patient dose information in terms of dose to water with variable electron density, the Monte Carlo method calculates the energy deposition in different media and expresses dose to a medium. This paper discusses the differences in dose calculated using water with different electron densities and that calculated for different biological media and the clinical issues on dose specification including dose prescription and plan evaluation using dose to water and dose to medium. We will demonstrate that conventional photon dose calculation algorithms compute doses similar to those simulated by Monte Carlo using water with different electron densities, which are close (<4% differences) to doses to media but significantly different (up to 11%) from doses to water converted from doses to media following American Association of Physicists in Medicine (AAPM) Task Group 105 recommendations. Our results suggest that for consistency with previous radiation therapy experience Monte Carlo photon algorithms report dose to medium for radiotherapy dose prescription, treatment plan evaluation and treatment outcome analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y M; Bush, K; Han, B

Purpose: Accurate and fast dose calculation is a prerequisite of precision radiation therapy in modern photon and particle therapy. While Monte Carlo (MC) dose calculation provides high dosimetric accuracy, the drastically increased computational time hinders its routine use. Deterministic dose calculation methods are fast, but problematic in the presence of tissue density inhomogeneity. We leverage the useful features of deterministic methods and MC to develop a hybrid dose calculation platform with autonomous utilization of MC and deterministic calculation depending on the local geometry, for optimal accuracy and speed. Methods: Our platform utilizes a Geant4 based “localized Monte Carlo” (LMC) methodmore » that isolates MC dose calculations only to volumes that have potential for dosimetric inaccuracy. In our approach, additional structures are created encompassing heterogeneous volumes. Deterministic methods calculate dose and energy fluence up to the volume surfaces, where the energy fluence distribution is sampled into discrete histories and transported using MC. Histories exiting the volume are converted back into energy fluence, and transported deterministically. By matching boundary conditions at both interfaces, deterministic dose calculation account for dose perturbations “downstream” of localized heterogeneities. Hybrid dose calculation was performed for water and anthropomorphic phantoms. Results: We achieved <1% agreement between deterministic and MC calculations in the water benchmark for photon and proton beams, and dose differences of 2%–15% could be observed in heterogeneous phantoms. The saving in computational time (a factor ∼4–7 compared to a full Monte Carlo dose calculation) was found to be approximately proportional to the volume of the heterogeneous region. Conclusion: Our hybrid dose calculation approach takes advantage of the computational efficiency of deterministic method and accuracy of MC, providing a practical tool for high performance dose calculation in modern RT. The approach is generalizable to all modalities where heterogeneities play a large role, notably particle therapy.« less

Modeling and optimization of sensory changes and shelf-life in vacuum-packaged cooked ham treated by E-beam irradiation

NASA Astrophysics Data System (ADS)

Benedito, J.; Cambero, M. I.; Ortuño, C.; Cabeza, M. C.; Ordoñez, J. A.; de la Hoz, L.

2011-03-01

The E-beam irradiation of vacuum-packaged RTE cooked ham was carried out to establish the dose required to achieve the food safety objective (FSO) and to minimize changes in selected sensory attributes. Cooked ham was irradiated with doses ranging 1-4 kGy. After the treatment, the microbial inactivation of Listeria monocytogenes, the shelf-life of the product and some sensory attributes (appearance, odor, and flavor) were determined. The inactivation of L. monocytogenes was satisfactorily described by a first-order kinetics equation ( R2=0.99). The influence of the irradiation dose on appearance, odor, and flavor was modeled through Gompertz ( R2=0.99, for appearance) and Activation/Inactivation ( R2=0.99, for odor and flavor) equations. A model was also developed to determine the shelf-life of irradiated cooked ham depending on the irradiation dose ( R2>0.91). The dose that maximized the scores of the sensory attributes was 0.96 kGy resulting in an acceptable sensory quality for 80 days. It is possible to apply up to 2 kGy to ensure microbial safety, while provoking no significant changes in the above mentioned sensory attributes.

A new protocol for evaluating the efficacy of some dispensing systems of a packaging in the microbial protection of water-based preservative-free cosmetic products.

PubMed

Devlieghere, F; De Loy-Hendrickx, A; Rademaker, M; Pipelers, P; Crozier, A; De Baets, B; Joly, L; Keromen, S

2015-12-01

A new protocol is described for assessing the efficacy of the dispenser of some packaging systems (PSs) of preservative-free cosmetic products in protecting both their contained formula and their delivered doses. Practically, aiming at mimicking contacts with a non-sterile skin or fingers, the dispensing system is put into contact with a pre-contaminated fabric by a standardized colonization of P. aeruginosa. When applied to three different types of packaging, results show clear differences in both criteria between these conditioning articles, that is variable efficacies in protecting the contained product and the delivered doses, knowing that the first aspect is of paramount importance. The proposed protocol is proved being able to discriminate between different PSs and provides information on strong and weak features of certain types dispensing technologies prone to efficiently decrease either the dose contamination or to prevent contamination in reaching the contained product. Therefore, the proposed protocol can contribute to an objective selection of a PS for protecting a cosmetic care product with a low content of preservative or preservative free. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

A study of the nonprescription drug consumer's understanding of the ranitidine product label and actual product usage patterns in the treatment of episodic heartburn.

PubMed

Ciociola, A A; Sirgo, M A; Pappa, K A; McGuire, J A; Fung, K

2001-01-01

A study of the consumer's understanding of the product label instructions and the resulting product use were conducted to support the switch of a product from prescription to nonprescription status. H2 receptor antagonists have recently been approved for nonprescription use. This study evaluated the consumer's understanding of the product label for ranitidine hydrochloride (Zantac 75) and the product usage pattern in the treatment of episodic heartburn. Our objectives were to evaluate each aspect of the communication of labeled indications, contraindications, and directions for use of two label formats (old and new) for a new nonprescription preparation of ranitidine (Zantac) and to evaluate nonprescription consumers' use of ranitidine 75-mg tablets (as Zantac 75) in a medically unsupervised, at-home setting to observe whether these consumers used the product appropriately and followed directions as written on the package label. Adult male and female consumers (n = 1405) in a shopping mall environment who were attracted to a poster asking, "Do you have stomach problems?" were recruited for the label comprehension phase (two different label formats) and the 3-week usage phase if after reading the Zantac 75 package label they decided the product was appropriate for them. No instructions regarding the use of Zantac 75 were provided beyond what was printed on the package label. Subjects recorded use in a diary and tablet counts were performed at the end of the study period. A medical history was also taken at this time and an assessment of product use was performed by a physician. In at least 84% of all subjects, both formats were effective in the communication of label objectives for the contraindication against concurrent prescription stomach ulcer medication, maximum daily dose, and maximum duration of dosing at maximum daily doses. The direction to take one tablet per dose was adhered to by 90% of consumers, and 90% of consumers followed the instructions to take no more than two tablets in 24 hours. Ninety-six percent of consumers complied with the direction not to take the maximum daily dose for more than 14 consecutive days. Notably, the maximum daily dose was taken for < or =3 consecutive days by 79% of consumers. The most frequently reported adverse events were headache, acute nasopharyngitis, upper respiratory tract infection, diarrhea, nausea, and menstrual cramps. The study demonstrated that the vast majority of a large sample of unsupervised consumers understood the package label and fully complied with the package directions by not exceeding the maximum daily dosage and length of use. Nonprescription consumers safely used Zantac 75 without medical supervision.

PLATSIM: A Simulation and Analysis Package for Large-Order Flexible Systems. Version 2.0

NASA Technical Reports Server (NTRS)

Maghami, Peiman G.; Kenny, Sean P.; Giesy, Daniel P.

1997-01-01

The software package PLATSIM provides efficient time and frequency domain analysis of large-order generic space platforms. PLATSIM can perform open-loop analysis or closed-loop analysis with linear or nonlinear control system models. PLATSIM exploits the particular form of sparsity of the plant matrices for very efficient linear and nonlinear time domain analysis, as well as frequency domain analysis. A new, original algorithm for the efficient computation of open-loop and closed-loop frequency response functions for large-order systems has been developed and is implemented within the package. Furthermore, a novel and efficient jitter analysis routine which determines jitter and stability values from time simulations in a very efficient manner has been developed and is incorporated in the PLATSIM package. In the time domain analysis, PLATSIM simulates the response of the space platform to disturbances and calculates the jitter and stability values from the response time histories. In the frequency domain analysis, PLATSIM calculates frequency response function matrices and provides the corresponding Bode plots. The PLATSIM software package is written in MATLAB script language. A graphical user interface is developed in the package to provide convenient access to its various features.

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

NASA Astrophysics Data System (ADS)

Cassola, V. F.; Milian, F. M.; Kramer, R.; de Oliveira Lira, C. A. B.; Khoury, H. J.

2011-07-01

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

Two-year experience with the commercial Gamma Knife Check software.

PubMed

Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Novotny, Josef; Flickinger, John; Lunsford, L Dade; Huq, M Saiful

2016-07-08

The Gamma Knife Check software is an FDA approved second check system for dose calculations in Gamma Knife radiosurgery. The purpose of this study was to evaluate the accuracy and the stability of the commercial software package as a tool for independent dose verification. The Gamma Knife Check software version 8.4 was commissioned for a Leksell Gamma Knife Perfexion and a 4C unit at the University of Pittsburgh Medical Center in May 2012. Independent dose verifications were performed using this software for 319 radiosurgery cases on the Perfexion and 283 radiosurgery cases on the 4C units. The cases on each machine were divided into groups according to their diagnoses, and an averaged absolute percent dose difference for each group was calculated. The percentage dose difference for each treatment target was obtained as the relative difference between the Gamma Knife Check dose and the dose from the tissue maximum ratio algorithm (TMR 10) from the GammaPlan software version 10 at the reference point. For treatment plans with imaging skull definition, results obtained from the Gamma Knife Check software using the measurement-based skull definition method are used for comparison. The collected dose difference data were also analyzed in terms of the distance from the treatment target to the skull, the number of treatment shots used for the target, and the gamma angles of the treatment shots. The averaged percent dose differences between the Gamma Knife Check software and the GammaPlan treatment planning system are 0.3%, 0.89%, 1.24%, 1.09%, 0.83%, 0.55%, 0.33%, and 1.49% for the trigeminal neuralgia, acoustic neuroma, arteriovenous malformation (AVM), meningioma, pituitary adenoma, glioma, functional disorders, and metastasis cases on the Perfexion unit. The corresponding averaged percent dose differences for the 4C unit are 0.33%, 1.2%, 2.78% 1.99%, 1.4%, 1.92%, 0.62%, and 1.51%, respectively. The dose difference is, in general, larger for treatment targets in the peripheral regions of the skull owing to the difference in the numerical methods used for skull shape simulation in the GammaPlan and the Gamma Knife Check software. Larger than 5% dose differences were observed on both machines for certain targets close to patient skull surface and for certain targets in the lower half of the brain on the Perfexion, especially when shots with 70 and/or 110 gamma angles are used. Out of the 1065 treatment targets studied, a 5% cutoff criterion cannot always be met for the dose differences between the studied versions of the Gamma Knife Check software and the planning system for 40 treatment targets. © 2016 The Authors.

Two‐year experience with the commercial Gamma Knife Check software

PubMed Central

Bhatnagar, Jagdish; Bednarz, Greg; Novotny, Josef; Flickinger, John; Lunsford, L. Dade; Huq, M. Saiful

2016-01-01

The Gamma Knife Check software is an FDA approved second check system for dose calculations in Gamma Knife radiosurgery. The purpose of this study was to evaluate the accuracy and the stability of the commercial software package as a tool for independent dose verification. The Gamma Knife Check software version 8.4 was commissioned for a Leksell Gamma Knife Perfexion and a 4C unit at the University of Pittsburgh Medical Center in May 2012. Independent dose verifications were performed using this software for 319 radiosurgery cases on the Perfexion and 283 radiosurgery cases on the 4C units. The cases on each machine were divided into groups according to their diagnoses, and an averaged absolute percent dose difference for each group was calculated. The percentage dose difference for each treatment target was obtained as the relative difference between the Gamma Knife Check dose and the dose from the tissue maximum ratio algorithm (TMR 10) from the GammaPlan software version 10 at the reference point. For treatment plans with imaging skull definition, results obtained from the Gamma Knife Check software using the measurement‐based skull definition method are used for comparison. The collected dose difference data were also analyzed in terms of the distance from the treatment target to the skull, the number of treatment shots used for the target, and the gamma angles of the treatment shots. The averaged percent dose differences between the Gamma Knife Check software and the GammaPlan treatment planning system are 0.3%, 0.89%, 1.24%, 1.09%, 0.83%, 0.55%, 0.33%, and 1.49% for the trigeminal neuralgia, acoustic neuroma, arteriovenous malformation (AVM), meningioma, pituitary adenoma, glioma, functional disorders, and metastasis cases on the Perfexion unit. The corresponding averaged percent dose differences for the 4C unit are 0.33%, 1.2%, 2.78% 1.99%, 1.4%, 1.92%, 0.62%, and 1.51%, respectively. The dose difference is, in general, larger for treatment targets in the peripheral regions of the skull owing to the difference in the numerical methods used for skull shape simulation in the GammaPlan and the Gamma Knife Check software. Larger than 5% dose differences were observed on both machines for certain targets close to patient skull surface and for certain targets in the lower half of the brain on the Perfexion, especially when shots with 70 and/or 110 gamma angles are used. Out of the 1065 treatment targets studied, a 5% cutoff criterion cannot always be met for the dose differences between the studied versions of the Gamma Knife Check software and the planning system for 40 treatment targets. PACS number(s): 87.55.Qr, 87.56.Fc PMID:27455470

The kinship2 R package for pedigree data.

PubMed

Sinnwell, Jason P; Therneau, Terry M; Schaid, Daniel J

2014-01-01

The kinship2 package is restructured from the previous kinship package. Existing features are now enhanced and new features added for handling pedigree objects. Pedigree plotting features have been updated to display features on complex pedigrees while adhering to pedigree plotting standards. Kinship matrices can now be calculated for the X chromosome. Other methods have been added to subset and trim pedigrees while maintaining the pedigree structure. We make the kinship2 package available for R on the Contributed R Archives Network (CRAN), where data management is built-in and other packages can use the pedigree object.

WannierTools: An open-source software package for novel topological materials

NASA Astrophysics Data System (ADS)

Wu, QuanSheng; Zhang, ShengNan; Song, Hai-Feng; Troyer, Matthias; Soluyanov, Alexey A.

2018-03-01

We present an open-source software package WannierTools, a tool for investigation of novel topological materials. This code works in the tight-binding framework, which can be generated by another software package Wannier90 (Mostofi et al., 2008). It can help to classify the topological phase of a given material by calculating the Wilson loop, and can get the surface state spectrum, which is detected by angle resolved photoemission (ARPES) and in scanning tunneling microscopy (STM) experiments. It also identifies positions of Weyl/Dirac points and nodal line structures, calculates the Berry phase around a closed momentum loop and Berry curvature in a part of the Brillouin zone (BZ).

Sampling of Stochastic Input Parameters for Rockfall Calculations and for Structural Response Calculations Under Vibratory Ground Motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Gross

2004-09-01

The purpose of this scientific analysis is to define the sampled values of stochastic (random) input parameters for (1) rockfall calculations in the lithophysal and nonlithophysal zones under vibratory ground motions, and (2) structural response calculations for the drip shield and waste package under vibratory ground motions. This analysis supplies: (1) Sampled values of ground motion time history and synthetic fracture pattern for analysis of rockfall in emplacement drifts in nonlithophysal rock (Section 6.3 of ''Drift Degradation Analysis'', BSC 2004 [DIRS 166107]); (2) Sampled values of ground motion time history and rock mechanical properties category for analysis of rockfall inmore » emplacement drifts in lithophysal rock (Section 6.4 of ''Drift Degradation Analysis'', BSC 2004 [DIRS 166107]); (3) Sampled values of ground motion time history and metal to metal and metal to rock friction coefficient for analysis of waste package and drip shield damage to vibratory motion in ''Structural Calculations of Waste Package Exposed to Vibratory Ground Motion'' (BSC 2004 [DIRS 167083]) and in ''Structural Calculations of Drip Shield Exposed to Vibratory Ground Motion'' (BSC 2003 [DIRS 163425]). The sampled values are indices representing the number of ground motion time histories, number of fracture patterns and rock mass properties categories. These indices are translated into actual values within the respective analysis and model reports or calculations. This report identifies the uncertain parameters and documents the sampled values for these parameters. The sampled values are determined by GoldSim V6.04.007 [DIRS 151202] calculations using appropriate distribution types and parameter ranges. No software development or model development was required for these calculations. The calculation of the sampled values allows parameter uncertainty to be incorporated into the rockfall and structural response calculations that support development of the seismic scenario for the Total System Performance Assessment for the License Application (TSPA-LA). The results from this scientific analysis also address project requirements related to parameter uncertainty, as specified in the acceptance criteria in ''Yucca Mountain Review Plan, Final Report'' (NRC 2003 [DIRS 163274]). This document was prepared under the direction of ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 170528]) which directed the work identified in work package ARTM05. This document was prepared under procedure AP-SIII.9Q, ''Scientific Analyses''. There are no specific known limitations to this analysis.« less

HADOC: a computer code for calculation of external and inhalation doses from acute radionuclide releases

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

The computer code HADOC (Hanford Acute Dose Calculations) is described and instructions for its use are presented. The code calculates external dose from air submersion and inhalation doses following acute radionuclide releases. Atmospheric dispersion is calculated using the Hanford model with options to determine maximum conditions. Building wake effects and terrain variation may also be considered. Doses are calculated using dose conversion factor supplied in a data library. Doses are reported for one and fifty year dose commitment periods for the maximum individual and the regional population (within 50 miles). The fractional contribution to dose by radionuclide and exposure modemore » are also printed if requested.« less

A computational framework for automation of point defect calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goyal, Anuj; Gorai, Prashun; Peng, Haowei

We have developed a complete and rigorously validated open-source Python framework to automate point defect calculations using density functional theory. Furthermore, the framework provides an effective and efficient method for defect structure generation, and creation of simple yet customizable workflows to analyze defect calculations. This package provides the capability to compute widely-accepted correction schemes to overcome finite-size effects, including (1) potential alignment, (2) image-charge correction, and (3) band filling correction to shallow defects. Using Si, ZnO and In2O3 as test examples, we demonstrate the package capabilities and validate the methodology.

A computational framework for automation of point defect calculations

DOE PAGES

Goyal, Anuj; Gorai, Prashun; Peng, Haowei; ...

2017-01-13

We have developed a complete and rigorously validated open-source Python framework to automate point defect calculations using density functional theory. Furthermore, the framework provides an effective and efficient method for defect structure generation, and creation of simple yet customizable workflows to analyze defect calculations. This package provides the capability to compute widely-accepted correction schemes to overcome finite-size effects, including (1) potential alignment, (2) image-charge correction, and (3) band filling correction to shallow defects. Using Si, ZnO and In2O3 as test examples, we demonstrate the package capabilities and validate the methodology.

SU-E-T-609: Perturbation Effects of Pedicle Screws On Radiotherapy Dose Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bar-Deroma, R; Borzov, E; Nevelsky, A

2015-06-15

Purpose: Radiation therapy in conjunction with surgical implant fixation is a common combined treatment in case of bone metastases. However, metal implants generally used in orthopedic implants perturb radiation dose distributions. Carbon-Fiber Reinforced (CFR) PEEK material has been recently introduced for production of intramedullary screws and plates. Gold powder can be added to the CFR-PEEK material in order to enhance visibility of the screws during intraoperative imaging procedures. In this work, we investigated the perturbation effects of the pedicle screws made of CFR-PEEK, CFR-PEEK with added gold powder (CFR-PEEK-AU) and Titanium (Ti) on radiotherapy dose distributions. Methods: Monte Carlo (MC)more » simulations were performed using the EGSnrc code package for 6MV beams with 10×10 fields at SSD=100cm. By means of MC simulations, dose distributions around titanium, CFR- PEEK and CFR-PEEK-AU screws (manufactured by Carbo-Fix Orthopedics LTD, Israel) placed in a water phantom were calculated. The screw axis was either parallel or perpendicular to the beam axis. Dose perturbation (relative to dose in homogeneous water phantom) was assessed. Results: Maximum overdose due to backscatter was 10% for the Ti screws, 5% for the CFR-PEEK-AU screws and effectively zero for the CFR-PEEK screws. Maximum underdose due to attenuation was 25% for the Ti screws, 15% for the CFR-PEEK-AU screws and 5% for the CFR-PEEK screws. Conclusion: Titanium screws introduce the largest distortion on the radiation dose distribution. The gold powder added to the CFR-PEEK material improves visibility at the cost of increased dose perturbation. CFR-PEEK screws caused minimal alteration on the dose distribution. This can decrease possible over and underdose of adjacent tissue and thus favorably influence treatment efficiency. The use of such implants has potential clinical advantage in the treatment of neoplastic bone disease.« less

The Impact of Monte Carlo Dose Calculations on Intensity-Modulated Radiation Therapy

NASA Astrophysics Data System (ADS)

Siebers, J. V.; Keall, P. J.; Mohan, R.

The effect of dose calculation accuracy for IMRT was studied by comparing different dose calculation algorithms. A head and neck IMRT plan was optimized using a superposition dose calculation algorithm. Dose was re-computed for the optimized plan using both Monte Carlo and pencil beam dose calculation algorithms to generate patient and phantom dose distributions. Tumor control probabilities (TCP) and normal tissue complication probabilities (NTCP) were computed to estimate the plan outcome. For the treatment plan studied, Monte Carlo best reproduces phantom dose measurements, the TCP was slightly lower than the superposition and pencil beam results, and the NTCP values differed little.

Effect of γ-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials

NASA Astrophysics Data System (ADS)

George, Johnsy; Kumar, R.; Sajeevkumar, V. A.; Sabapathy, S. N.; Vaijapurkar, S. G.; Kumar, D.; Kchawahha, A.; Bawa, A. S.

2007-07-01

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of γ-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity.

Determination of the spatial resolution required for the HEDR dose code. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities, Calculation 007

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, B.A.; Simpson, J.C.

1992-12-01

A series of scoping calculations has been undertaken to evaluate the doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 007) examined the spatial distribution of potential doses resulting from releases in the year 1945. This study builds on the work initiated in the first scoping calculation, of iodine in cow`s milk; the third scoping calculation, which added additional pathways; the fifth calculation, which addressed the uncertainty of the dose estimates at a point; and the sixth calculation, which extrapolated the doses throughout the atmospheric transport domain. A projectionmore » of dose to representative individuals throughout the proposed HEDR atmospheric transport domain was prepared on the basis of the HEDR source term. Addressed in this calculation were the contributions to iodine-131 thyroid dose of infants from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows` milk from-Feeding Regime 1 as described in scoping calculation 001.« less

Use of DandD for dose assessment under NRC`s radiological criteria for license termination rule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gallegos, D.P.; Brown, T.J.; Davis, P.A.

The Decontamination and Decommissioning (DandD) software package has been developed by Sandia National Laboratories for the Nuclear Regulatory Commission (NRC) specifically for the purpose of providing a user-friendly analytical tool to address the dose criteria contained in NRC`s Radiological Criteria for License Termination rule (10 CFR Part 20 Subpart E; NRC, 1997). Specifically, DandD embodies the NRC`s screening methodology to allow licensees to convert residual radioactivity contamination levels at their site to annual dose, in a manner consistent with both 10 CFR Part 20 and the corresponding implementation guidance developed by NRC. The screening methodology employs reasonably conservative scenarios, fatemore » and transport models, and default parameter values that have been developed to allow the NRC to quantitatively estimate the risk of releasing a site given only information about the level of contamination. Therefore, a licensee has the option of specifying only the level of contamination and running the code with the default parameter values, or in the case where site specific information is available to alter the appropriate parameter values and then calculate dose. DandD can evaluate dose for fur different scenarios: residential, building occupancy, building renovation, or drinking water. The screening methodology and DandD are part of a larger decision framework that allows and encourages licensees to optimize decisions on choice of alternative actions at their site, including collection of additional data and information. This decision framework is integrated into and documented in NRC`s technical guidance for decommissioning.« less

Evaluation of the Eclipse eMC algorithm for bolus electron conformal therapy using a standard verification dataset.

PubMed

Carver, Robert L; Sprunger, Conrad P; Hogstrom, Kenneth R; Popple, Richard A; Antolak, John A

2016-05-08

The purpose of this study was to evaluate the accuracy and calculation speed of electron dose distributions calculated by the Eclipse electron Monte Carlo (eMC) algorithm for use with bolus electron conformal therapy (ECT). The recent com-mercial availability of bolus ECT technology requires further validation of the eMC dose calculation algorithm. eMC-calculated electron dose distributions for bolus ECT have been compared to previously measured TLD-dose points throughout patient-based cylindrical phantoms (retromolar trigone and nose), whose axial cross sections were based on the mid-PTV (planning treatment volume) CT anatomy. The phantoms consisted of SR4 muscle substitute, SR4 bone substitute, and air. The treatment plans were imported into the Eclipse treatment planning system, and electron dose distributions calculated using 1% and < 0.2% statistical uncertainties. The accuracy of the dose calculations using moderate smoothing and no smooth-ing were evaluated. Dose differences (eMC-calculated less measured dose) were evaluated in terms of absolute dose difference, where 100% equals the given dose, as well as distance to agreement (DTA). Dose calculations were also evaluated for calculation speed. Results from the eMC for the retromolar trigone phantom using 1% statistical uncertainty without smoothing showed calculated dose at 89% (41/46) of the measured TLD-dose points was within 3% dose difference or 3 mm DTA of the measured value. The average dose difference was -0.21%, and the net standard deviation was 2.32%. Differences as large as 3.7% occurred immediately distal to the mandible bone. Results for the nose phantom, using 1% statistical uncertainty without smoothing, showed calculated dose at 93% (53/57) of the measured TLD-dose points within 3% dose difference or 3 mm DTA. The average dose difference was 1.08%, and the net standard deviation was 3.17%. Differences as large as 10% occurred lateral to the nasal air cavities. Including smoothing had insignificant effects on the accuracy of the retromolar trigone phantom calculations, but reduced the accuracy of the nose phantom calculations in the high-gradient dose areas. Dose calculation times with 1% statistical uncertainty for the retromolar trigone and nose treatment plans were 30 s and 24 s, respectively, using 16 processors (Intel Xeon E5-2690, 2.9 GHz) on a framework agent server (FAS). In comparison, the eMC was significantly more accurate than the pencil beam algorithm (PBA). The eMC has comparable accuracy to the pencil beam redefinition algorithm (PBRA) used for bolus ECT planning and has acceptably low dose calculation times. The eMC accuracy decreased when smoothing was used in high-gradient dose regions. The eMC accuracy was consistent with that previously reported for accuracy of the eMC electron dose algorithm and shows that the algorithm is suitable for clinical implementation of bolus ECT.

Electron tunneling in proteins program.

PubMed

Hagras, Muhammad A; Stuchebrukhov, Alexei A

2016-06-05

We developed a unique integrated software package (called Electron Tunneling in Proteins Program or ETP) which provides an environment with different capabilities such as tunneling current calculation, semi-empirical quantum mechanical calculation, and molecular modeling simulation for calculation and analysis of electron transfer reactions in proteins. ETP program is developed as a cross-platform client-server program in which all the different calculations are conducted at the server side while only the client terminal displays the resulting calculation outputs in the different supported representations. ETP program is integrated with a set of well-known computational software packages including Gaussian, BALLVIEW, Dowser, pKip, and APBS. In addition, ETP program supports various visualization methods for the tunneling calculation results that assist in a more comprehensive understanding of the tunneling process. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsuta, Y; Tohoku University Graduate School of Medicine, Sendal, Miyagi; Kadoya, N

Purpose: In this study, we developed a system to calculate three dimensional (3D) dose that reflects dosimetric error caused by leaf miscalibration for head and neck and prostate volumetric modulated arc therapy (VMAT) without additional treatment planning system calculation on real time. Methods: An original system called clarkson dose calculation based dosimetric error calculation to calculate dosimetric error caused by leaf miscalibration was developed by MATLAB (Math Works, Natick, MA). Our program, first, calculates point doses at isocenter for baseline and modified VMAT plan, which generated by inducing MLC errors that enlarged aperture size of 1.0 mm with clarkson dosemore » calculation. Second, error incuced 3D dose was generated with transforming TPS baseline 3D dose using calculated point doses. Results: Mean computing time was less than 5 seconds. For seven head and neck and prostate plans, between our method and TPS calculated error incuced 3D dose, the 3D gamma passing rates (0.5%/2 mm, global) are 97.6±0.6% and 98.0±0.4%. The dose percentage change with dose volume histogram parameter of mean dose on target volume were 0.1±0.5% and 0.4±0.3%, and with generalized equivalent uniform dose on target volume were −0.2±0.5% and 0.2±0.3%. Conclusion: The erroneous 3D dose calculated by our method is useful to check dosimetric error caused by leaf miscalibration before pre treatment patient QA dosimetry checks.« less

Improving the Efficiency of Free Energy Calculations in the Amber Molecular Dynamics Package.

PubMed

Kaus, Joseph W; Pierce, Levi T; Walker, Ross C; McCammont, J Andrew

2013-09-10

Alchemical transformations are widely used methods to calculate free energies. Amber has traditionally included support for alchemical transformations as part of the sander molecular dynamics (MD) engine. Here we describe the implementation of a more efficient approach to alchemical transformations in the Amber MD package. Specifically we have implemented this new approach within the more computational efficient and scalable pmemd MD engine that is included with the Amber MD package. The majority of the gain in efficiency comes from the improved design of the calculation, which includes better parallel scaling and reduction in the calculation of redundant terms. This new implementation is able to reproduce results from equivalent simulations run with the existing functionality, but at 2.5 times greater computational efficiency. This new implementation is also able to run softcore simulations at the λ end states making direct calculation of free energies more accurate, compared to the extrapolation required in the existing implementation. The updated alchemical transformation functionality will be included in the next major release of Amber (scheduled for release in Q1 2014) and will be available at http://ambermd.org, under the Amber license.

Batch calculations in CalcHEP

NASA Astrophysics Data System (ADS)

Pukhov, A.

2003-04-01

CalcHEP is a clone of the CompHEP project which is developed by the author outside of the CompHEP group. CompHEP/CalcHEP are packages for automatic calculations of elementary particle decay and collision properties in the lowest order of perturbation theory. The main idea prescribed into the packages is to make available passing on from the Lagrangian to the final distributions effectively with a high level of automation. According to this, the packages were created as a menu driven user friendly programs for calculations in the interactive mode. From the other side, long-time calculations should be done in the non-interactive regime. Thus, from the beginning CompHEP has a problem of batch calculations. In CompHEP 33.23 the batch session was realized by mean of interactive menu which allows to the user to formulate the task for batch. After that the not-interactive session was launched. This way is too restricted, not flexible, and leads to doubling in programming. In this article I discuss another approach how one can force an interactive program to work in non-interactive mode. This approach was realized in CalcHEP 2.1 disposed on http://theory.sinp.msu.ru/~pukhov/calchep.html.

Improving the Efficiency of Free Energy Calculations in the Amber Molecular Dynamics Package

PubMed Central

Pierce, Levi T.; Walker, Ross C.; McCammont, J. Andrew

2013-01-01

Alchemical transformations are widely used methods to calculate free energies. Amber has traditionally included support for alchemical transformations as part of the sander molecular dynamics (MD) engine. Here we describe the implementation of a more efficient approach to alchemical transformations in the Amber MD package. Specifically we have implemented this new approach within the more computational efficient and scalable pmemd MD engine that is included with the Amber MD package. The majority of the gain in efficiency comes from the improved design of the calculation, which includes better parallel scaling and reduction in the calculation of redundant terms. This new implementation is able to reproduce results from equivalent simulations run with the existing functionality, but at 2.5 times greater computational efficiency. This new implementation is also able to run softcore simulations at the λ end states making direct calculation of free energies more accurate, compared to the extrapolation required in the existing implementation. The updated alchemical transformation functionality will be included in the next major release of Amber (scheduled for release in Q1 2014) and will be available at http://ambermd.org, under the Amber license. PMID:24185531

Pharmacokinetics of escin Ia in rats after intravenous administration.

PubMed

Wu, Xiu-Jun; Cui, Xiang-Yong; Tian, Lian-tian; Gao, Feng; Guan, Xin; Gu, Jing-Kai

2014-10-28

Escin, a natural mixture of triterpene saponins, is commonly utilized for the treatment of chronic venous insufficiency, hemorrhoids, inflammation and edema. Escin Ia is the chief active ingredient in escin and plays key role in mediating its pharmacological effects. Adequate pharmacokinetic data are essential for proper application of escin agent in clinical practice. However, pharmacokinetic properties of escin Ia are still poorly understood and this conflicts with the growing use of escin agent over the years. The goal of this study is to investigate the pharmacokinetic behavior of escin Ia in rats after low, medium and high-dose intravenous administration. Wistar rats were divided into 3 groups (n=6 per group) and escin Ia was administered via the caudal vein at doses of 0.5, 1.0 and 2.0 mg/kg, respectively. Subsequently, the concentrations of escin Ia and its metabolite isoescin Ia, a positional isomer of escin Ia, in rats׳ plasma were measured by an established liquid chromatography tandem mass spectrometry (LC-MS/MS) method at various time points following the administration of the drug. Main pharmacokinetic parameters were calculated by non-compartmental analysis using the TopFit 2.0 software package (Thomae GmbH, Germany). After intravenous administration, the Cmax and AUC of escin Ia increased in a dose-proportional manner at the dose of 0.5 mg/kg and 1.0 mg/kg, while increased in a more than dose-proportional manner at the doses of 1.0 mg/kg and 2.0 mg/kg. The t₁/₂ was significantly longer with increased intravenous doses, while other parameters such as CL and Vd also exhibit disagreement among three doses. Taken together, our data showed dose-dependent pharmacokinetic profile of escin Ia in rats after intravenous administration at the doses of 0.5-2.0 mg/kg. After intravenous administration, escin Ia was rapidly and extensively converted to isoescin Ia. The results suggested dose-dependent pharmacokinetics of escin Ia at the doses of 0.5-2.0 mg/kg after intravenous administration. Escin Ia is isomerized to isoescin Ia rapidly and extensively regardless of the doses. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Calculation of Organ Doses for a Large Number of Patients Undergoing CT Examinations.

PubMed

Bahadori, Amir; Miglioretti, Diana; Kruger, Randell; Flynn, Michael; Weinmann, Sheila; Smith-Bindman, Rebecca; Lee, Choonsik

2015-10-01

The objective of our study was to develop an automated calculation method to provide organ dose assessment for a large cohort of pediatric and adult patients undergoing CT examinations. We adopted two dose libraries that were previously published: the volume CT dose index-normalized organ dose library and the tube current-exposure time product (100 mAs)-normalized weighted CT dose index library. We developed an algorithm to calculate organ doses using the two dose libraries and the CT parameters available from DICOM data. We calculated organ doses for pediatric (n = 2499) and adult (n = 2043) CT examinations randomly selected from four health care systems in the United States and compared the adult organ doses with the values calculated from the ImPACT calculator. The median brain dose was 20 mGy (pediatric) and 24 mGy (adult), and the brain dose was greater than 40 mGy for 11% (pediatric) and 18% (adult) of the head CT studies. Both the National Cancer Institute (NCI) and ImPACT methods provided similar organ doses (median discrepancy < 20%) for all organs except the organs located close to the scanning boundaries. The visual comparisons of scanning coverage and phantom anatomies revealed that the NCI method, which is based on realistic computational phantoms, provides more accurate organ doses than the ImPACT method. The automated organ dose calculation method developed in this study reduces the time needed to calculate doses for a large number of patients. We have successfully used this method for a variety of CT-related studies including retrospective epidemiologic studies and CT dose trend analysis studies.

Push plate, mounting assembly, circuit board, and method of assembling thereof for ball grid array packages

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaughn, Mark R.; Montague, Stephen

A push plate that includes springs in the form of cantilever flexures and an inspection window is disclosed. The push plate provides a known, uniform, down force and minimal torque to a package to be tested. The cantilevers have a known, calculable down force producing stiffness. The window provides for viewing of the package during testing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwai, P; Lins, L Nadler

Purpose: There is a lack of studies with significant cohort data about patients using pacemaker (PM), implanted cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) device undergoing radiotherapy. There is no literature comparing the cumulative doses delivered to those cardiac implanted electronic devices (CIED) calculated by different algorithms neither studies comparing doses with heterogeneity correction or not. The aim of this study was to evaluate the influence of the algorithms Pencil Beam Convolution (PBC), Analytical Anisotropic Algorithm (AAA) and Acuros XB (AXB) as well as heterogeneity correction on risk categorization of patients. Methods: A retrospective analysis of 19 3DCRT ormore » IMRT plans of 17 patients was conducted, calculating the dose delivered to CIED using three different calculation algorithms. Doses were evaluated with and without heterogeneity correction for comparison. Risk categorization of the patients was based on their CIED dependency and cumulative dose in the devices. Results: Total estimated doses at CIED calculated by AAA or AXB were higher than those calculated by PBC in 56% of the cases. In average, the doses at CIED calculated by AAA and AXB were higher than those calculated by PBC (29% and 4% higher, respectively). The maximum difference of doses calculated by each algorithm was about 1 Gy, either using heterogeneity correction or not. Values of maximum dose calculated with heterogeneity correction showed that dose at CIED was at least equal or higher in 84% of the cases with PBC, 77% with AAA and 67% with AXB than dose obtained with no heterogeneity correction. Conclusion: The dose calculation algorithm and heterogeneity correction did not change the risk categorization. Since higher estimated doses delivered to CIED do not compromise treatment precautions to be taken, it’s recommend that the most sophisticated algorithm available should be used to predict dose at the CIED using heterogeneity correction.« less

Estimating age-based antiretroviral therapy costs for HIV-infected children in resource-limited settings based on World Health Organization weight-based dosing recommendations

PubMed Central

2014-01-01

Background Pediatric antiretroviral therapy (ART) has been shown to substantially reduce morbidity and mortality in HIV-infected infants and children. To accurately project program costs, analysts need accurate estimations of antiretroviral drug (ARV) costs for children. However, the costing of pediatric antiretroviral therapy is complicated by weight-based dosing recommendations which change as children grow. Methods We developed a step-by-step methodology for estimating the cost of pediatric ARV regimens for children ages 0–13 years old. The costing approach incorporates weight-based dosing recommendations to provide estimated ARV doses throughout childhood development. Published unit drug costs are then used to calculate average monthly drug costs. We compared our derived monthly ARV costs to published estimates to assess the accuracy of our methodology. Results The estimates of monthly ARV costs are provided for six commonly used first-line pediatric ARV regimens, considering three possible care scenarios. The costs derived in our analysis for children were fairly comparable to or slightly higher than available published ARV drug or regimen estimates. Conclusions The methodology described here can be used to provide an accurate estimation of pediatric ARV regimen costs for cost-effectiveness analysts to project the optimum packages of care for HIV-infected children, as well as for program administrators and budget analysts who wish to assess the feasibility of increasing pediatric ART availability in constrained budget environments. PMID:24885453

Target prices for mass production of tyrosine kinase inhibitors for global cancer treatment

PubMed Central

Hill, Andrew; Gotham, Dzintars; Fortunak, Joseph; Meldrum, Jonathan; Erbacher, Isabelle; Martin, Manuel; Shoman, Haitham; Levi, Jacob; Powderly, William G; Bower, Mark

2016-01-01

Objective To calculate sustainable generic prices for 4 tyrosine kinase inhibitors (TKIs). Background TKIs have proven survival benefits in the treatment of several cancers, including chronic myeloid leukaemia, breast, liver, renal and lung cancer. However, current high prices are a barrier to treatment. Mass production of low-cost generic antiretrovirals has led to over 13 million people being on HIV/AIDS treatment worldwide. This analysis estimates target prices for generic TKIs, assuming similar methods of mass production. Methods Four TKIs with patent expiry dates in the next 5 years were selected for analysis: imatinib, erlotinib, lapatinib and sorafenib. Chemistry, dosing, published data on per-kilogram pricing for commercial transactions of active pharmaceutical ingredient (API), and quotes from manufacturers were used to estimate costs of production. Analysis included costs of excipients, formulation, packaging, shipping and a 50% profit margin. Target prices were compared with current prices. Global numbers of patients eligible for treatment with each TKI were estimated. Results API costs per kg were $347–$746 for imatinib, $2470 for erlotinib, $4671 for lapatinib, and $3000 for sorafenib. Basing on annual dose requirements, costs of formulation/packaging and a 50% profit margin, target generic prices per person-year were $128–$216 for imatinib, $240 for erlotinib, $1450 for sorafenib, and $4020 for lapatinib. Over 1 million people would be newly eligible to start treatment with these TKIs annually. Conclusions Mass generic production of several TKIs could achieve treatment prices in the range of $128–$4020 per person-year, versus current US prices of $75161–$139 138. Generic TKIs could allow significant savings and scaling-up of treatment globally, for over 1 million eligible patients. PMID:26817636

Beyond-use dating of lidocaine alone and in two "magic mouthwash" preparations.

PubMed

Kirk, Loren Madden; Brown, Stacy D; Luu, Yao; Ogle, Amanda; Huffman, Jessica; Lewis, Paul O

2017-05-01

Beyond-use dating (BUD) of lidocaine alone and in two "magic mouthwash" preparations stored in amber oral syringes at room temperature was determined. Two formulations of mouthwash containing oral topical lidocaine 2% (viscous), diphenhydramine 2.5 mg/mL, and aluminum hydroxide-magnesium hydroxide-simethicone were prepared in 1:1:1 and 1:2.5:2.5 ratios, divided into 3-mL samples, and stored in unit-dose oral amber syringes. Unit-dose single-product lidocaine samples were also prepared to serve as controls and stored in oral amber syringes. The lidocaine concentrations in these samples were measured periodically for 90 days. A stability-indicating high-performance liquid chromatographic method was developed and validated for system suitability, accuracy, repeatability, intermediate precision, specificity, linearity, and robustness. Based on the calculated percentages versus the initial concentration and the results from an analysis of variance comparing the two formulations, a BUD of 21 days is deemed appropriate for both magic mouthwash formulations. Based on the stability data, published safety concerns, and lack of efficacy in combination, packaging and dispensing lidocaine separately from other ingredients are recommended when administering magic mouthwash mixtures. Utilizing a 90-day BUD, lidocaine can be packaged separately from other magic mouthwash ingredients in individual dosage units and applied to the oral cavity using the swish-and-spit method. The delivery of the diphenhydramine and aluminum hydroxide-magnesium hydroxide-simethicone could be separated, allowing for a swish-and-swallow method of administration. A BUD of 21 days is recommended for lidocaine prepared with diphenhydramine and aluminum hydroxide-magnesium hydroxide-simethicone in ratios of 1:1:1 and 1:2.5:2.5 and stored at room temperature in amber oral plastic syringes. Copyright © 2017 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Considerations for applying VARSKIN mod 2 to skin dose calculations averaged over 10 cm2.

PubMed

Durham, James S

2004-02-01

VARSKIN Mod 2 is a DOS-based computer program that calculates the dose to skin from beta and gamma contamination either directly on skin or on material in contact with skin. The default area for calculating the dose is 1 cm2. Recently, the U.S. Nuclear Regulatory Commission issued new guidelines for calculating shallow dose equivalent from skin contamination that requires the dose be averaged over 10 cm2. VARSKIN Mod 2 was not filly designed to calculate beta or gamma dose estimates averaged over 10 cm2, even though the program allows the user to calculate doses averaged over 10 cm2. This article explains why VARSKIN Mod 2 overestimates the beta dose when applied to 10 cm2 areas, describes a manual method for correcting the overestimate, and explains how to perform reasonable gamma dose calculations averaged over 10 cm2. The article also describes upgrades underway in Varskin 3.

Energy deposition studies for the high-luminosity Large Hadron Collider inner triplet magnets

NASA Astrophysics Data System (ADS)

Mokhov, N. V.; Rakhno, I. L.; Tropin, I. S.; Cerutti, F.; Esposito, L. S.; Lechner, A.

2015-05-01

A detailed model of the high-luminosity LHC inner triplet region with new large-aperture Nb3Sn magnets, field maps, corrector packages, and segmented tungsten inner absorbers was built and implemented into the fluka and mars15 codes. Detailed simulations have been performed coherently with the codes on the impact of particle debris from the 14-TeV center-of-mass pp-collisions on the short- and long-term stability of the inner triplet magnets. After optimizing the absorber configuration, the peak power density averaged over the magnet inner cable width is found to be safely below the quench limit at the luminosity of 5 ×1034 cm-2 s-1 . For the anticipated lifetime integrated luminosity of 3000 fb-1 , the peak dose calculated for the innermost magnet insulator ranges from 20 to 35 MGy, a figure close to the commonly accepted limit. Dynamic heat loads to the triplet magnet cold mass are calculated to evaluate the cryogenic capability. fluka and mars results on energy deposition are in very good agreement.

MCNPX Cosmic Ray Shielding Calculations with the NORMAN Phantom Model

NASA Technical Reports Server (NTRS)

James, Michael R.; Durkee, Joe W.; McKinney, Gregg; Singleterry Robert

2008-01-01

The United States is planning manned lunar and interplanetary missions in the coming years. Shielding from cosmic rays is a critical aspect of manned spaceflight. These ventures will present exposure issues involving the interplanetary Galactic Cosmic Ray (GCR) environment. GCRs are comprised primarily of protons (approx.84.5%) and alpha-particles (approx.14.7%), while the remainder is comprised of massive, highly energetic nuclei. The National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) has commissioned a joint study with Los Alamos National Laboratory (LANL) to investigate the interaction of the GCR environment with humans using high-fidelity, state-of-the-art computer simulations. The simulations involve shielding and dose calculations in order to assess radiation effects in various organs. The simulations are being conducted using high-resolution voxel-phantom models and the MCNPX[1] Monte Carlo radiation-transport code. Recent advances in MCNPX physics packages now enable simulated transport over 2200 types of ions of widely varying energies in large, intricate geometries. We report here initial results obtained using a GCR spectrum and a NORMAN[3] phantom.

Energy deposition studies for the high-luminosity Large Hadron Collider inner triplet magnets

DOE PAGES

Mokhov, N. V.; Rakhno, I. L.; Tropin, I. S.; ...

2015-05-06

A detailed model of the high-luminosity LHC inner triplet region with new large-aperture Nb 3Sn magnets, field maps, corrector packages, and segmented tungsten inner absorbers was built and implemented into the fluka and mars15 codes. Detailed simulations have been performed coherently with the codes on the impact of particle debris from the 14-TeV center-of-mass pp-collisions on the short- and long-term stability of the inner triplet magnets. After optimizing the absorber configuration, the peak power density averaged over the magnet inner cable width is found to be safely below the quench limit at the luminosity of 5×10 34 cm -2s -1.more » For the anticipated lifetime integrated luminosity of 3000 fb -1, the peak dose calculated for the innermost magnet insulator ranges from 20 to 35 MGy, a figure close to the commonly accepted limit. Dynamic heat loads to the triplet magnet cold mass are calculated to evaluate the cryogenic capability. fluka and mars results on energy deposition are in very good agreement.« less

Monte Carlo evaluation of RapidArc™ oropharynx treatment planning strategies for sparing of midline structures

NASA Astrophysics Data System (ADS)

Bush, K.; Zavgorodni, S.; Gagne, I.; Townson, R.; Ansbacher, W.; Beckham, W.

2010-08-01

The aim of the study was to perform the Monte Carlo (MC) evaluation of RapidArc™ (Varian Medical Systems, Palo Alto, CA) dose calculations for four oropharynx midline sparing planning strategies. Six patients with squamous cell cancer of the oropharynx were each planned with four RapidArc head and neck treatment strategies consisting of single and double photon arcs. In each case, RTOG0522 protocol objectives were used during planning optimization. Dose calculations performed with the analytical anisotropic algorithm (AAA) are compared against BEAMnrc/DOSXYZnrc dose calculations for the 24-plan dataset. Mean dose and dose-to-98%-of-structure-volume (D98%) were used as metrics in the evaluation of dose to planning target volumes (PTVs). Mean dose and dose-to-2%-of-structure-volume (D2%) were used to evaluate dose differences within organs at risk (OAR). Differences in the conformity index (CI) and the homogeneity index (HI) as well as 3D dose distributions were also observed. AAA calculated PTV mean dose, D98%, and HIs showed very good agreement with MC dose calculations within the 0.8% MC (statistical) calculation uncertainty. Regional node volume (PTV-80%) mean dose and D98% were found to be overestimated (1.3%, σ = 0.8% and 2.3%, σ = 0.8%, respectively) by the AAA with respect to MC calculations. Mean dose and D2% to OAR were also observed to be consistently overestimated by the AAA. Increasing dose calculation differences were found in planning strategies exhibiting a higher overall fluence modulation. From the plan dataset, the largest local dose differences were observed in heavily shielded regions and within the esophageal and sinus cavities. AAA dose calculations as implemented in RapidArc™ demonstrate excellent agreement with MC calculations in unshielded regions containing moderate inhomogeneities. Acceptable agreement is achieved in regions of increased MLC shielding. Differences in dose are attributed to inaccuracies in the AAA-modulated fluence modeling, modeling of material inhomogeneities and dose deposition within low-density materials. The use of MC dose calculations leads to the same general conclusion as using AAA that a two arc delivery with limited collimator opening can provide the greatest amount of midline sparing compared to the other techniques investigated.

Effect of high-dose irradiation on quality characteristics of ready-to-eat broiler breast fillets stored at room temperature.

PubMed

Baptista, R F; Teixeira, C E; Lemos, M; Monteiro, M L G; Vital, H C; Mársico, E T; Júnior, C A Conte; Mano, S B

2014-10-01

The effect of high-dose irradiation on the physical, chemical, and bacteriological parameters of ready-to-eat vacuum-packed broiler breast meat after 430 d of storage at room temperature was investigated. Ready-to-eat broiler breast fillets were immersed in brine with garlic powder and then drained, grilled, and vacuum-packed (primary packaging). The high-dose irradiation used was approximately 48 kGy. The treatments were designated as A (irradiated samples stored at room temperature), B (irradiated samples stored at -25°C), and C (nonirradiated samples stored at -25°C). All samples were packaged in polyethylene bags containing aluminum to exclude light (secondary packaging). Proximate composition, pH, 2-thiobarbituric acid reactive substance (TBARS), and heterotrophic aerobic mesophilic bacteria were analyzed during 430 d of storage. Results were analyzed using 1-way ANOVA and the Tukey test. Linear regression was used to analyze the correlation between the results for each parameter and storage time of the different treatments. The gamma radiation caused slight changes (P < 0.05) in the moisture and fat content, regardless of storage temperature. After storage d 110, TBARS values remained stable (P > 0.05) in all the treatments. The preservation methods used were effective in maintaining the mesophilic counts below the detection level during the entire storage period. We concluded that, among the treatments studied, high-dose irradiation with storage at room temperature showed potential for the preservation of ready-to-eat products made from poultry meat, to provide foods safe for consumption. ©2014 Poultry Science Association Inc.

2011 drug packaging review: too many dangers and too many patients overlooked.

PubMed

2012-05-01

Every year, Prescrire's analysis of drug packaging confirms the importance of taking packaging into account in assessing a drug's harm-benefit balance. Safe, tried and true options are available, yet the quality of most of the drug packaging Prescrire examined in 2011 left much to be desired. Few of the packaging items examined help prevent medication errors and many actually increase the risks: misleading and confusing labelling, dosing devices that create a risk of overdose, bottles without a child-proof cap, and inadequate or dangerous patient information leaflets. Umbrella brands continue to expand and are a potential source of medication errors. Some patients are at greater risk: the patient leaflets for NSAIDs endanger pregnant women and their unborn babies; children are insufficiently protected by paediatric packaging and are at risk due to the lack of child-proof caps on too many bottles. The raft of regulatory measures taken by the French drug regulatory agency (Afssaps) in the aftermath of the Mediator disaster overlooked the importance of packaging. Until drug regulatory agencies tackle the vast issue of drug packaging, it is up to healthcare professionals to protect patients from harm.

Regulations on consume and commercialization of food irradiation in Mexico

NASA Astrophysics Data System (ADS)

Bustos Ramírez, Ma. Emilia; Jiménez Pérez, Jesús

1995-02-01

A Mexican standard for food irradiation is ready for final publication after the authority received and reviewed public comments of the project published in April 1994. The standard establish the radiation doses for different classes of food, based on ICGFI recommendations. Also included are controls for sampling, packaging, labelling, transportation, process inspection and accordance with international regulations. The results of the economical analysis of cost-benefit of the application of the standard show that the net present value is positive. The method of calculation is presented explaining the assumptions considered for the estimation of the total annual savings and surveillance costs. A final version of the research program report on radiation quarantine treatment of Mexican mangoes will be used for the petition to APHIS for the amendment of quarantine procedures to permit importation into the USA of irradiated products.

Guidelines for the analysis of free energy calculations.

PubMed

Klimovich, Pavel V; Shirts, Michael R; Mobley, David L

2015-05-01

Free energy calculations based on molecular dynamics simulations show considerable promise for applications ranging from drug discovery to prediction of physical properties and structure-function studies. But these calculations are still difficult and tedious to analyze, and best practices for analysis are not well defined or propagated. Essentially, each group analyzing these calculations needs to decide how to conduct the analysis and, usually, develop its own analysis tools. Here, we review and recommend best practices for analysis yielding reliable free energies from molecular simulations. Additionally, we provide a Python tool, alchemical-analysis.py, freely available on GitHub as part of the pymbar package (located at http://github.com/choderalab/pymbar), that implements the analysis practices reviewed here for several reference simulation packages, which can be adapted to handle data from other packages. Both this review and the tool covers analysis of alchemical calculations generally, including free energy estimates via both thermodynamic integration and free energy perturbation-based estimators. Our Python tool also handles output from multiple types of free energy calculations, including expanded ensemble and Hamiltonian replica exchange, as well as standard fixed ensemble calculations. We also survey a range of statistical and graphical ways of assessing the quality of the data and free energy estimates, and provide prototypes of these in our tool. We hope this tool and discussion will serve as a foundation for more standardization of and agreement on best practices for analysis of free energy calculations.

Excore Modeling with VERAShift

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandya, Tara M.; Evans, Thomas M.

It is important to be able to accurately predict the neutron flux outside the immediate reactor core for a variety of safety and material analyses. Monte Carlo radiation transport calculations are required to produce the high fidelity excore responses. Under this milestone VERA (specifically the VERAShift package) has been extended to perform excore calculations by running radiation transport calculations with Shift. This package couples VERA-CS with Shift to perform excore tallies for multiple state points concurrently, with each component capable of parallel execution on independent domains. Specifically, this package performs fluence calculations in the core barrel and vessel, or, performsmore » the requested tallies in any user-defined excore regions. VERAShift takes advantage of the general geometry package in Shift. This gives VERAShift the flexibility to explicitly model features outside the core barrel, including detailed vessel models, detectors, and power plant details. A very limited set of experimental and numerical benchmarks is available for excore simulation comparison. The Consortium for the Advanced Simulation of Light Water Reactors (CASL) has developed a set of excore benchmark problems to include as part of the VERA-CS verification and validation (V&V) problems. The excore capability in VERAShift has been tested on small representative assembly problems, multiassembly problems, and quarter-core problems. VERAView has also been extended to visualize these vessel fluence results from VERAShift. Preliminary vessel fluence results for quarter-core multistate calculations look very promising. Further development is needed to determine the details relevant to excore simulations. Validation of VERA for fluence and excore detectors still needs to be performed against experimental and numerical results.« less

Influence of dose calculation algorithms on the predicted dose distribution and NTCP values for NSCLC patients.

PubMed

Nielsen, Tine B; Wieslander, Elinore; Fogliata, Antonella; Nielsen, Morten; Hansen, Olfred; Brink, Carsten

2011-05-01

To investigate differences in calculated doses and normal tissue complication probability (NTCP) values between different dose algorithms. Six dose algorithms from four different treatment planning systems were investigated: Eclipse AAA, Oncentra MasterPlan Collapsed Cone and Pencil Beam, Pinnacle Collapsed Cone and XiO Multigrid Superposition, and Fast Fourier Transform Convolution. Twenty NSCLC patients treated in the period 2001-2006 at the same accelerator were included and the accelerator used for treatments were modeled in the different systems. The treatment plans were recalculated with the same number of monitor units and beam arrangements across the dose algorithms. Dose volume histograms of the GTV, PTV, combined lungs (excluding the GTV), and heart were exported and evaluated. NTCP values for heart and lungs were calculated using the relative seriality model and the LKB model, respectively. Furthermore, NTCP for the lungs were calculated from two different model parameter sets. Calculations and evaluations were performed both including and excluding density corrections. There are found statistical significant differences between the calculated dose to heart, lung, and targets across the algorithms. Mean lung dose and V20 are not very sensitive to change between the investigated dose calculation algorithms. However, the different dose levels for the PTV averaged over the patient population are varying up to 11%. The predicted NTCP values for pneumonitis vary between 0.20 and 0.24 or 0.35 and 0.48 across the investigated dose algorithms depending on the chosen model parameter set. The influence of the use of density correction in the dose calculation on the predicted NTCP values depends on the specific dose calculation algorithm and the model parameter set. For fixed values of these, the changes in NTCP can be up to 45%. Calculated NTCP values for pneumonitis are more sensitive to the choice of algorithm than mean lung dose and V20 which are also commonly used for plan evaluation. The NTCP values for heart complication are, in this study, not very sensitive to the choice of algorithm. Dose calculations based on density corrections result in quite different NTCP values than calculations without density corrections. It is therefore important when working with NTCP planning to use NTCP parameter values based on calculations and treatments similar to those for which the NTCP is of interest.

Patient-specific CT dosimetry calculation: a feasibility study.

PubMed

Fearon, Thomas; Xie, Huchen; Cheng, Jason Y; Ning, Holly; Zhuge, Ying; Miller, Robert W

2011-11-15

Current estimation of radiation dose from computed tomography (CT) scans on patients has relied on the measurement of Computed Tomography Dose Index (CTDI) in standard cylindrical phantoms, and calculations based on mathematical representations of "standard man". Radiation dose to both adult and pediatric patients from a CT scan has been a concern, as noted in recent reports. The purpose of this study was to investigate the feasibility of adapting a radiation treatment planning system (RTPS) to provide patient-specific CT dosimetry. A radiation treatment planning system was modified to calculate patient-specific CT dose distributions, which can be represented by dose at specific points within an organ of interest, as well as organ dose-volumes (after image segmentation) for a GE Light Speed Ultra Plus CT scanner. The RTPS calculation algorithm is based on a semi-empirical, measured correction-based algorithm, which has been well established in the radiotherapy community. Digital representations of the physical phantoms (virtual phantom) were acquired with the GE CT scanner in axial mode. Thermoluminescent dosimeter (TLDs) measurements in pediatric anthropomorphic phantoms were utilized to validate the dose at specific points within organs of interest relative to RTPS calculations and Monte Carlo simulations of the same virtual phantoms (digital representation). Congruence of the calculated and measured point doses for the same physical anthropomorphic phantom geometry was used to verify the feasibility of the method. The RTPS algorithm can be extended to calculate the organ dose by calculating a dose distribution point-by-point for a designated volume. Electron Gamma Shower (EGSnrc) codes for radiation transport calculations developed by National Research Council of Canada (NRCC) were utilized to perform the Monte Carlo (MC) simulation. In general, the RTPS and MC dose calculations are within 10% of the TLD measurements for the infant and child chest scans. With respect to the dose comparisons for the head, the RTPS dose calculations are slightly higher (10%-20%) than the TLD measurements, while the MC results were within 10% of the TLD measurements. The advantage of the algebraic dose calculation engine of the RTPS is a substantially reduced computation time (minutes vs. days) relative to Monte Carlo calculations, as well as providing patient-specific dose estimation. It also provides the basis for a more elaborate reporting of dosimetric results, such as patient specific organ dose volumes after image segmentation.

CheMentor Software System by H. A. Peoples

NASA Astrophysics Data System (ADS)

Reid, Brian P.

1997-09-01

CheMentor Software System H. A. Peoples. Computerized Learning Enhancements: http://www.ecis.com/~clehap; email: clehap@ecis.com; 1996 - 1997. CheMentor is a series of software packages for introductory-level chemistry, which includes Practice Items (I), Stoichiometry (I), Calculating Chemical Formulae, and the CheMentor Toolkit. The first three packages provide practice problems for students and various types of help to solve them; the Toolkit includes "calculators" for determining chemical quantities as well as the Practice Items (I) set of problems. The set of software packages is designed so that each individual product acts as a module of a common CheMentor program. As the name CheMentor implies, the software is designed as a "mentor" for students learning introductory chemistry concepts and problems. The typical use of the software would be by individual students (or perhaps small groups) as an adjunct to lectures. CheMentor is a HyperCard application and the modules are HyperCard stacks. The requirements to run the packages include a Macintosh computer with at least 1 MB of RAM, a hard drive with several MB of available space depending upon the packages selected (10 MB were required for all the packages reviewed here), and the Mac operating system 6.0.5 or later.

TMAP: Tübingen NLTE Model-Atmosphere Package

NASA Astrophysics Data System (ADS)

Werner, Klaus; Dreizler, Stefan; Rauch, Thomas

2012-12-01

The Tübingen NLTE Model-Atmosphere Package (TMAP) is a tool to calculate stellar atmospheres in spherical or plane-parallel geometry in hydrostatic and radiative equilibrium allowing departures from local thermodynamic equilibrium (LTE) for the population of atomic levels. It is based on the Accelerated Lambda Iteration (ALI) method and is able to account for line blanketing by metals. All elements from hydrogen to nickel may be included in the calculation with model atoms which are tailored for the aims of the user.

Improving spot-scanning proton therapy patient specific quality assurance with HPlusQA, a second-check dose calculation engine.

PubMed

Mackin, Dennis; Li, Yupeng; Taylor, Michael B; Kerr, Matthew; Holmes, Charles; Sahoo, Narayan; Poenisch, Falk; Li, Heng; Lii, Jim; Amos, Richard; Wu, Richard; Suzuki, Kazumichi; Gillin, Michael T; Zhu, X Ronald; Zhang, Xiaodong

2013-12-01

The purpose of this study was to validate the use of HPlusQA, spot-scanning proton therapy (SSPT) dose calculation software developed at The University of Texas MD Anderson Cancer Center, as second-check dose calculation software for patient-specific quality assurance (PSQA). The authors also showed how HPlusQA can be used within the current PSQA framework. The authors compared the dose calculations of HPlusQA and the Eclipse treatment planning system with 106 planar dose measurements made as part of PSQA. To determine the relative performance and the degree of correlation between HPlusQA and Eclipse, the authors compared calculated with measured point doses. Then, to determine how well HPlusQA can predict when the comparisons between Eclipse calculations and the measured dose will exceed tolerance levels, the authors compared gamma index scores for HPlusQA versus Eclipse with those of measured doses versus Eclipse. The authors introduce the αβγ transformation as a way to more easily compare gamma scores. The authors compared measured and calculated dose planes using the relative depth, z∕R × 100%, where z is the depth of the measurement and R is the proton beam range. For relative depths than less than 80%, both Eclipse and HPlusQA calculations were within 2 cGy of dose measurements on average. When the relative depth was greater than 80%, the agreement between the calculations and measurements fell to 4 cGy. For relative depths less than 10%, the Eclipse and HPlusQA dose discrepancies showed a negative correlation, -0.21. Otherwise, the correlation between the dose discrepancies was positive and as large as 0.6. For the dose planes in this study, HPlusQA correctly predicted when Eclipse had and had not calculated the dose to within tolerance 92% and 79% of the time, respectively. In 4 of 106 cases, HPlusQA failed to predict when the comparison between measurement and Eclipse's calculation had exceeded the tolerance levels of 3% for dose and 3 mm for distance-to-agreement. The authors found HPlusQA to be reasonably effective (79% ± 10%) in determining when the comparison between measured dose planes and the dose planes calculated by the Eclipse treatment planning system had exceeded the acceptable tolerance levels. When used as described in this study, HPlusQA can reduce the need for patient specific quality assurance measurements by 64%. The authors believe that the use of HPlusQA as a dose calculation second check can increase the efficiency and effectiveness of the QA process.

Consumption of raw vegetables and fruits: a risk factor for Campylobacter infections.

PubMed

Verhoeff-Bakkenes, L; Jansen, H A P M; in 't Veld, P H; Beumer, R R; Zwietering, M H; van Leusden, F M

2011-01-05

The purpose of this study was to determine the prevalence of Campylobacter in fresh vegetables and fruits at retail level in the Netherlands, and to estimate its implications on the importance of vegetables and fruits as risk factor for campylobacteriosis. Thirteen of the 5640 vegetable and fruit samples were Campylobacter positive, resulting in a prevalence of 0.23% (95% confidence interval (Cl): 0.12-0.39%). The prevalence of packaged products (0.36%, 95% Cl: 0.17-0.66) was significantly higher than of unpackaged products (0.07; 95% Cl: 0.01-0.27). No statistical differences were found between seasons. Combining the mean prevalence found in this study with data on the consumption of vegetables and fruits, an exposure of 0.0048 campylobacters ingested per person per day in the Netherlands by transmission via vegetables and fruits, was calculated. This exposure, as input in a Beta-Poisson dose-response model, resulted in an estimated number of 5.3×10⁵ cases of infection with Campylobacter per year for the whole Dutch population. This constitutes the consumption of raw vegetables and fruits, especially when packaged, to be a risk factor for Campylobacter infections. Copyright © 2010 Elsevier B.V. All rights reserved.

Influence of CT contrast agent on dose calculation of intensity modulated radiation therapy plan for nasopharyngeal carcinoma.

PubMed

Lee, F K-H; Chan, C C-L; Law, C-K

2009-02-01

Contrast enhanced computed tomography (CECT) has been used for delineation of treatment target in radiotherapy. The different Hounsfield unit due to the injected contrast agent may affect radiation dose calculation. We investigated this effect on intensity modulated radiotherapy (IMRT) of nasopharyngeal carcinoma (NPC). Dose distributions of 15 IMRT plans were recalculated on CECT. Dose statistics for organs at risk (OAR) and treatment targets were recorded for the plain CT-calculated and CECT-calculated plans. Statistical significance of the differences was evaluated. Correlations were also tested, among magnitude of calculated dose difference, tumor size and level of enhancement contrast. Differences in nodal mean/median dose were statistically significant, but small (approximately 0.15 Gy for a 66 Gy prescription). In the vicinity of the carotid arteries, the difference in calculated dose was also statistically significant, but only with a mean of approximately 0.2 Gy. We did not observe any significant correlation between the difference in the calculated dose and the tumor size or level of enhancement. The results implied that the calculated dose difference was clinically insignificant and may be acceptable for IMRT planning.

PynPoint code for exoplanet imaging

NASA Astrophysics Data System (ADS)

Amara, A.; Quanz, S. P.; Akeret, J.

2015-04-01

We announce the public release of PynPoint, a Python package that we have developed for analysing exoplanet data taken with the angular differential imaging observing technique. In particular, PynPoint is designed to model the point spread function of the central star and to subtract its flux contribution to reveal nearby faint companion planets. The current version of the package does this correction by using a principal component analysis method to build a basis set for modelling the point spread function of the observations. We demonstrate the performance of the package by reanalysing publicly available data on the exoplanet β Pictoris b, which consists of close to 24,000 individual image frames. We show that PynPoint is able to analyse this typical data in roughly 1.5 min on a Mac Pro, when the number of images is reduced by co-adding in sets of 5. The main computational work, the calculation of the Singular-Value-Decomposition, parallelises well as a result of a reliance on the SciPy and NumPy packages. For this calculation the peak memory load is 6 GB, which can be run comfortably on most workstations. A simpler calculation, by co-adding over 50, takes 3 s with a peak memory usage of 600 MB. This can be performed easily on a laptop. In developing the package we have modularised the code so that we will be able to extend functionality in future releases, through the inclusion of more modules, without it affecting the users application programming interface. We distribute the PynPoint package under GPLv3 licence through the central PyPI server, and the documentation is available online (http://pynpoint.ethz.ch).

The challenge of international consensus: defining an opioid essential prescription package.

PubMed

Vignaroli, Ernesto; Wenk, Roberto

2012-09-01

To describe a new strategy that aimed to facilitate opioid prescription for better pain management. The International Association of Hospice and Palliative Care recently develop a single prescription package (drugs and dosing) with one opioid, one laxative, and one antiemetic for the initiation of opioid treatment in cancer pain and other life-threatening conditions, with the intention to facilitate opioid use, improve patient compliance, and reduce adverse effects. The opioid essential prescription package was an international project designed to ensure that opioids are better tolerated by reducing the adverse effects of opioids, which could lead to more sustained improvements in pain management.

Determination of the spatial resolution required for the HEDR dose code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, B.A.; Simpson, J.C.

1992-12-01

A series of scoping calculations has been undertaken to evaluate the doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 007) examined the spatial distribution of potential doses resulting from releases in the year 1945. This study builds on the work initiated in the first scoping calculation, of iodine in cow's milk; the third scoping calculation, which added additional pathways; the fifth calculation, which addressed the uncertainty of the dose estimates at a point; and the sixth calculation, which extrapolated the doses throughout the atmospheric transport domain. A projectionmore » of dose to representative individuals throughout the proposed HEDR atmospheric transport domain was prepared on the basis of the HEDR source term. Addressed in this calculation were the contributions to iodine-131 thyroid dose of infants from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows' milk from-Feeding Regime 1 as described in scoping calculation 001.« less

Nuclear Waste Package Mockups: A Study of In-situ Redox State

NASA Astrophysics Data System (ADS)

Helean, K.; Anderson, B.; Brady, P. V.

2006-05-01

The Yucca Mountain Repository (YMR), located in southern Nevada, is to be the first facility in the U.S. for the permanent disposal of high-level radioactive waste and spent nuclear fuels. Total system performance assessment(TSPA) has indicated that among the major radionuclides contributing to dose are Np, Tc, and I. These three radionuclides are mobile in most geochemical settings, and therefore sequestering them within the repository horizon is a priority for the Yucca Mountain Project (YMP). Corroding steel may offset radionuclide transport processes within the proposed waste packages at YMR by retaining radionuclides, creating locally reducing conditions, and reducing porosity. Ferrous iron has been shown to reduce UO22+ to UO2s, and some ferrous iron-bearing ion-exchange materials have been shown to adsorb radionuclides and heavy metals. Locally reducing conditions may lead to the reduction and subsequent immobilization of problematic dissolved species such as TcO4-, NpO2+, and UO22+ and can also inhibit corrosion of spent nuclear fuel. Water occluded during corrosion produces bulky corrosion products, and consequently less porosity is available for water and radionuclide transport. The focus of this study is on the nature of Yucca Mountain waste package corrosion products and their effects on local redox conditions, radionuclide transport, and porosity. In order to measure in-situ redox, six small-scale (1:40) waste package mockups were constructed using A516 and 316 stainless steel, the same materials as the proposed Yucca Mountain waste packages. The mockups are periodically injected with a simulated groundwater and the accumulated effluent and corrosion products are evaluated for their Fe(II)/Fe(III) content and mineralogy. Oxygen fugacities are then calculated and, thus, in-situ redox conditions are determined. Early results indicate that corrosion products are largely amorphous Fe-oxyhydroxides, goethite and magnetite. That information together with the measured Fe(II)/Fe(III) ratios in the mockup effluent constrain the oxygen fugacity to approximately 10-38 atm, many orders of magnitude below ambient. These results and their impact on radionuclide migration from YMR will be discussed.

SCHEMA computational design of virus capsid chimeras: calibrating how genome packaging, protection, and transduction correlate with calculated structural disruption.

PubMed

Ho, Michelle L; Adler, Benjamin A; Torre, Michael L; Silberg, Jonathan J; Suh, Junghae

2013-12-20

Adeno-associated virus (AAV) recombination can result in chimeric capsid protein subunits whose ability to assemble into an oligomeric capsid, package a genome, and transduce cells depends on the inheritance of sequence from different AAV parents. To develop quantitative design principles for guiding site-directed recombination of AAV capsids, we have examined how capsid structural perturbations predicted by the SCHEMA algorithm correlate with experimental measurements of disruption in seventeen chimeric capsid proteins. In our small chimera population, created by recombining AAV serotypes 2 and 4, we found that protection of viral genomes and cellular transduction were inversely related to calculated disruption of the capsid structure. Interestingly, however, we did not observe a correlation between genome packaging and calculated structural disruption; a majority of the chimeric capsid proteins formed at least partially assembled capsids and more than half packaged genomes, including those with the highest SCHEMA disruption. These results suggest that the sequence space accessed by recombination of divergent AAV serotypes is rich in capsid chimeras that assemble into 60-mer capsids and package viral genomes. Overall, the SCHEMA algorithm may be useful for delineating quantitative design principles to guide the creation of libraries enriched in genome-protecting virus nanoparticles that can effectively transduce cells. Such improvements to the virus design process may help advance not only gene therapy applications but also other bionanotechnologies dependent upon the development of viruses with new sequences and functions.

SCHEMA computational design of virus capsid chimeras: calibrating how genome packaging, protection, and transduction correlate with calculated structural disruption

PubMed Central

Ho, Michelle L.; Adler, Benjamin A.; Torre, Michael L.; Silberg, Jonathan J.; Suh, Junghae

2013-01-01

Adeno-associated virus (AAV) recombination can result in chimeric capsid protein subunits whose ability to assemble into an oligomeric capsid, package a genome, and transduce cells depends on the inheritance of sequence from different AAV parents. To develop quantitative design principles for guiding site-directed recombination of AAV capsids, we have examined how capsid structural perturbations predicted by the SCHEMA algorithm correlate with experimental measurements of disruption in seventeen chimeric capsid proteins. In our small chimera population, created by recombining AAV serotypes 2 and 4, we found that protection of viral genomes and cellular transduction were inversely related to calculated disruption of the capsid structure. Interestingly, however, we did not observe a correlation between genome packaging and calculated structural disruption; a majority of the chimeric capsid proteins formed at least partially assembled capsids and more than half packaged genomes, including those with the highest SCHEMA disruption. These results suggest that the sequence space accessed by recombination of divergent AAV serotypes is rich in capsid chimeras that assemble into 60-mer capsids and package viral genomes. Overall, the SCHEMA algorithm may be useful for delineating quantitative design principles to guide the creation of libraries enriched in genome-protecting virus nanoparticles that can effectively transduce cells. Such improvements to the virus design process may help advance not only gene therapy applications, but also other bionanotechnologies dependent upon the development of viruses with new sequences and functions. PMID:23899192

Dose computation for therapeutic electron beams

NASA Astrophysics Data System (ADS)

Glegg, Martin Mackenzie

The accuracy of electron dose calculations performed by two commercially available treatment planning computers, Varian Cadplan and Helax TMS, has been assessed. Measured values of absorbed dose delivered by a Varian 2100C linear accelerator, under a wide variety of irradiation conditions, were compared with doses calculated by the treatment planning computers. Much of the motivation for this work was provided by a requirement to verify the accuracy of calculated electron dose distributions in situations encountered clinically at Glasgow's Beatson Oncology Centre. Calculated dose distributions are required in a significant minority of electron treatments, usually in cases involving treatment to the head and neck. Here, therapeutic electron beams are subject to factors which may cause non-uniformity in the distribution of dose, and which may complicate the calculation of dose. The beam shape is often irregular, the beam may enter the patient at an oblique angle or at an extended source to skin distance (SSD), tissue inhomogeneities can alter the dose distribution, and tissue equivalent material (such as wax) may be added to reduce dose to critical organs. Technological advances have allowed the current generation of treatment planning computers to implement dose calculation algorithms with the ability to model electron beams in these complex situations. These calculations have, however, yet to be verified by measurement. This work has assessed the accuracy of calculations in a number of specific instances. Chapter two contains a comparison of measured and calculated planar electron isodose distributions. Three situations were considered: oblique incidence, incidence on an irregular surface (such as that which would be arise from the use of wax to reduce dose to spinal cord), and incidence on a phantom containing a small air cavity. Calculations were compared with measurements made by thermoluminescent dosimetry (TLD) in a WTe electron solid water phantom. Chapter three assesses the planning computers' ability to model electron beam penumbra at extended SSD. Calculations were compared with diode measurements in a water phantom. Further measurements assessed doses in the junction region produced by abutting an extended SSD electron field with opposed photon fields. Chapter four describes an investigation of the size and shape of the region enclosed by the 90% isodose line when produced by limiting the electron beam with square and elliptical apertures. The 90% isodose line was chosen because clinical treatments are often prescribed such that a given volume receives at least 90% dose. Calculated and measured dose distributions were compared in a plane normal to the beam central axis. Measurements were made by film dosimetry. While chapters two to four examine relative doses, chapter five assesses the accuracy of absolute dose (or output) calculations performed by the planning computers. Output variation with SSD and field size was examined. Two further situations already assessed for the distribution of relative dose were also considered: an obliquely incident field, and a field incident on an irregular surface. The accuracy of calculations was assessed against criteria stipulated by the International Commission on Radiation Units and Measurement (ICRU). The Varian Cadplan and Helax TMS treatment planning systems produce acceptable accuracy in the calculation of relative dose from therapeutic electron beams in most commonly encountered situations. When interpreting clinical dose distributions, however, knowledge of the limitations of the calculation algorithm employed by each system is required in order to identify the minority of situations where results are not accurate. The calculation of absolute dose is too inaccurate to implement in a clinical environment. (Abstract shortened by ProQuest.).

Development of a silicon diode detector for skin dosimetry in radiotherapy.

PubMed

Vicoroski, Nikolina; Espinoza, Anthony; Duncan, Mitchell; Oborn, Bradley M; Carolan, Martin; Metcalfe, Peter; Menichelli, David; Perevertaylo, Vladimir L; Lerch, Michael L F; Rosenfeld, Anatoly B; Petasecca, Marco

2017-10-01

The aim of in vivo skin dosimetry was to measure the absorbed dose to the skin during radiotherapy, when treatment planning calculations cannot be relied on. It is of particularly importance in hypo-fractionated stereotactic modalities, where excessive dose can lead to severe skin toxicity. Currently, commercial diodes for such applications are with water equivalent depths ranging from 0.5 to 0.8 mm. In this study, we investigate a new detector for skin dosimetry based on a silicon epitaxial diode, referred to as the skin diode. The skin diode is manufactured on a thin epitaxial layer and packaged using the "drop-in" technology. It was characterized in terms of percentage depth dose, dose linearity, and dose rate dependence, and benchmarked against the Attix ionization chamber. The response of the skin diode in the build-up region of the percentage depth dose (PDD) curve of a 6 MV clinical photon beam was investigated. Geant4 radiation transport simulations were used to model the PDD in order to estimate the water equivalent measurement depth (WED) of the skin diode. Measured output factors using the skin diode were compared with the MOSkin detector and EBT3 film at 10 cm depth and at surface at isocenter of a water equivalent phantom. The intrinsic angular response of the skin diode was also quantified in charge particle equilibrium conditions (CPE) and at the surface of a solid water phantom. Finally, the radiation hardness of the skin diode up to an accumulated dose of 80 kGy using photons from a Co-60 gamma source was evaluated. The PDD curve measured with the skin diode was within 0.5% agreement of the equivalent Geant4 simulated curve. When placed at the phantom surface, the WED of the skin diode was estimated to be 0.075 ± 0.005 mm from Geant4 simulations and was confirmed using the response of a corrected Attix ionization chamber placed at water equivalent depth of 0.075 mm, with the measurement agreement to within 0.3%. The output factor measurements at 10 cm depth were within 2% of those measured with film and the MOSkin detector down to a field size of 2 × 2 cm 2 . The dose-response for all detector samples was linear and with a repeatability within 0.2%. The skin diode intrinsic angular response showed a maximum deviation of 8% at 90 degrees and from 0 to 60 degree is less than 5%. The radiation sensitivity reduced by 25% after an accumulated dose of 20 kGy but after was found to stabilize. At 60 kGy total accumulated dose the response was within 2% of that measured at 20 kGy total accumulated dose. This work characterizes an innovative detector for in vivo and real-time skin dose measurements that is based on an epitaxial silicon diode combined with the Centre for Medical Radiation Physics (CMRP) "drop-in" packaging technology. The skin diode proved to have a water equivalent depth of measurement of 0.075 ± 0.005 mm and the ability to measure doses accurately relative to reference detectors. © 2017 American Association of Physicists in Medicine.

Dose calculation and verification of the Vero gimbal tracking treatment delivery

NASA Astrophysics Data System (ADS)

Prasetio, H.; Wölfelschneider, J.; Ziegler, M.; Serpa, M.; Witulla, B.; Bert, C.

2018-02-01

The Vero linear accelerator delivers dynamic tumor tracking (DTT) treatment using a gimbal motion. However, the availability of treatment planning systems (TPS) to simulate DTT is limited. This study aims to implement and verify the gimbal tracking beam geometry in the dose calculation. Gimbal tracking was implemented by rotating the reference CT outside the TPS according to the ring, gantry, and gimbal tracking position obtained from the tracking log file. The dose was calculated using these rotated CTs. The geometric accuracy was verified by comparing calculated and measured film response using a ball bearing phantom. The dose was verified by comparing calculated 2D dose distributions and film measurements in a ball bearing and a homogeneous phantom using a gamma criterion of 2%/2 mm. The effect of implementing the gimbal tracking beam geometry in a 3D patient data dose calculation was evaluated using dose volume histograms (DVH). Geometrically, the gimbal tracking implementation accuracy was  <0.94 mm. The isodose lines agreed with the film measurement. The largest dose difference of 9.4% was observed at maximum tilt positions with an isocenter and target separation of 17.51 mm. Dosimetrically, gamma passing rates were  >98.4%. The introduction of the gimbal tracking beam geometry in the dose calculation shifted the DVH curves by 0.05%-1.26% for the phantom geometry and by 5.59% for the patient CT dataset. This study successfully demonstrates a method to incorporate the gimbal tracking beam geometry into dose calculations. By combining CT rotation and MU distribution according to the log file, the TPS was able to simulate the Vero tracking treatment dose delivery. The DVH analysis from the gimbal tracking dose calculation revealed changes in the dose distribution during gimbal DTT that are not visible with static dose calculations.

Acceleration of intensity-modulated radiotherapy dose calculation by importance sampling of the calculation matrices.

PubMed

Thieke, Christian; Nill, Simeon; Oelfke, Uwe; Bortfeld, Thomas

2002-05-01

In inverse planning for intensity-modulated radiotherapy, the dose calculation is a crucial element limiting both the maximum achievable plan quality and the speed of the optimization process. One way to integrate accurate dose calculation algorithms into inverse planning is to precalculate the dose contribution of each beam element to each voxel for unit fluence. These precalculated values are stored in a big dose calculation matrix. Then the dose calculation during the iterative optimization process consists merely of matrix look-up and multiplication with the actual fluence values. However, because the dose calculation matrix can become very large, this ansatz requires a lot of computer memory and is still very time consuming, making it not practical for clinical routine without further modifications. In this work we present a new method to significantly reduce the number of entries in the dose calculation matrix. The method utilizes the fact that a photon pencil beam has a rapid radial dose falloff, and has very small dose values for the most part. In this low-dose part of the pencil beam, the dose contribution to a voxel is only integrated into the dose calculation matrix with a certain probability. Normalization with the reciprocal of this probability preserves the total energy, even though many matrix elements are omitted. Three probability distributions were tested to find the most accurate one for a given memory size. The sampling method is compared with the use of a fully filled matrix and with the well-known method of just cutting off the pencil beam at a certain lateral distance. A clinical example of a head and neck case is presented. It turns out that a sampled dose calculation matrix with only 1/3 of the entries of the fully filled matrix does not sacrifice the quality of the resulting plans, whereby the cutoff method results in a suboptimal treatment plan.

Pressure Build-Up During the Fire Test in Type B(U) Packages Containing Water - 13280

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feldkamp, Martin; Nehrig, Marko; Bletzer, Claus

The safety assessment of packages for the transport of radioactive materials with content containing liquids requires special consideration. The main focus is on water as supplementary liquid content in Type B(U) packages. A typical content of a Type B(U) package is ion exchange resin, waste of a nuclear power plant, which is not dried, normally only drained. Besides the saturated ion exchange resin, a small amount of free water can be included in these contents. Compared to the safety assessment of packages with dry content, attention must be paid to some more specific issues. An overview of these issues ismore » provided. The physical and chemical compatibility of the content itself and the content compatibility with the packages materials must be demonstrated for the assessment. Regarding the mechanical resistance the package has to withstand the forces resulting from the freezing liquid. The most interesting point, however, is the pressure build-up inside the package due to vaporization. This could for example be caused by radiolysis of the liquid and must be taken into account for the storage period. If the package is stressed by the total inner pressure, this pressure leads to mechanical loads to the package body, the lid and the lid bolts. Thus, the pressure is the driving force on the gasket system regarding the activity release and a possible loss of tightness. The total pressure in any calculation is the sum of partial pressures of different gases which can be caused by different effects. The pressure build-up inside the package caused by the regulatory thermal test (30 min at 800 deg. C), as part of the cumulative test scenario under accident conditions of transport is discussed primarily. To determine the pressure, the temperature distribution in the content must be calculated for the whole period from beginning of the thermal test until cooling-down. In this case, while calculating the temperature distribution, conduction and radiation as well as evaporation and condensation during the associated process of transport have to be considered. This paper discusses limiting amounts of water inside the cask which could lead to unacceptable pressure and takes into account saturated steam as well as overheated steam. However, the difficulties of assessing casks containing wet content will be discussed. From the authority assessment point of view, drying of the content could be an effective way to avoid the above described pressure build-up and the associated difficulties for the safety assessment. (authors)« less

Cluster-lensing: A Python Package for Galaxy Clusters and Miscentering

NASA Astrophysics Data System (ADS)

Ford, Jes; VanderPlas, Jake

2016-12-01

We describe a new open source package for calculating properties of galaxy clusters, including Navarro, Frenk, and White halo profiles with and without the effects of cluster miscentering. This pure-Python package, cluster-lensing, provides well-documented and easy-to-use classes and functions for calculating cluster scaling relations, including mass-richness and mass-concentration relations from the literature, as well as the surface mass density {{Σ }}(R) and differential surface mass density {{Δ }}{{Σ }}(R) profiles, probed by weak lensing magnification and shear. Galaxy cluster miscentering is especially a concern for stacked weak lensing shear studies of galaxy clusters, where offsets between the assumed and the true underlying matter distribution can lead to a significant bias in the mass estimates if not accounted for. This software has been developed and released in a public GitHub repository, and is licensed under the permissive MIT license. The cluster-lensing package is archived on Zenodo. Full documentation, source code, and installation instructions are available at http://jesford.github.io/cluster-lensing/.

75 FR 11174 - Pesticide Product Registration Approval

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-10

..., contraceptive (EPA File Symbol 56228-GN), containing 1.0 milliliter doses in pre-packaged syringes at .03... product, Gonacon Immunocontraceptive Vaccine contraceptive. During the public comment period for this...

Wide-field Imaging System and Rapid Direction of Optical Zoom (WOZ)

DTIC Science & Technology

2010-09-25

commercial software packages: SolidWorks, COMSOL Multiphysics, and ZEMAX optical design. SolidWorks is a computer aided design package, which as a live...interface to COMSOL. COMSOL is a finite element analysis/partial differential equation solver. ZEMAX is an optical design package. Both COMSOL and... ZEMAX have live interfaces to MatLab. Our initial investigations have enabled a model in SolidWorks to be updated in COMSOL, an FEA calculation

Stereotactic, Single-Dose Irradiation of Lung Tumors: A Comparison of Absolute Dose and Dose Distribution Between Pencil Beam and Monte Carlo Algorithms Based on Actual Patient CT Scans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Huixiao; Lohr, Frank; Fritz, Peter

2010-11-01

Purpose: Dose calculation based on pencil beam (PB) algorithms has its shortcomings predicting dose in tissue heterogeneities. The aim of this study was to compare dose distributions of clinically applied non-intensity-modulated radiotherapy 15-MV plans for stereotactic body radiotherapy between voxel Monte Carlo (XVMC) calculation and PB calculation for lung lesions. Methods and Materials: To validate XVMC, one treatment plan was verified in an inhomogeneous thorax phantom with EDR2 film (Eastman Kodak, Rochester, NY). Both measured and calculated (PB and XVMC) dose distributions were compared regarding profiles and isodoses. Then, 35 lung plans originally created for clinical treatment by PB calculationmore » with the Eclipse planning system (Varian Medical Systems, Palo Alto, CA) were recalculated by XVMC (investigational implementation in PrecisePLAN [Elekta AB, Stockholm, Sweden]). Clinically relevant dose-volume parameters for target and lung tissue were compared and analyzed statistically. Results: The XVMC calculation agreed well with film measurements (<1% difference in lateral profile), whereas the deviation between PB calculation and film measurements was up to +15%. On analysis of 35 clinical cases, the mean dose, minimal dose and coverage dose value for 95% volume of gross tumor volume were 1.14 {+-} 1.72 Gy, 1.68 {+-} 1.47 Gy, and 1.24 {+-} 1.04 Gy lower by XVMC compared with PB, respectively (prescription dose, 30 Gy). The volume covered by the 9 Gy isodose of lung was 2.73% {+-} 3.12% higher when calculated by XVMC compared with PB. The largest differences were observed for small lesions circumferentially encompassed by lung tissue. Conclusions: Pencil beam dose calculation overestimates dose to the tumor and underestimates lung volumes exposed to a given dose consistently for 15-MV photons. The degree of difference between XVMC and PB is tumor size and location dependent. Therefore XVMC calculation is helpful to further optimize treatment planning.« less

Estimating the uncertainty of calculated out-of-field organ dose from a commercial treatment planning system.

PubMed

Wang, Lilie; Ding, George X

2018-06-12

Therapeutic radiation to cancer patients is accompanied by unintended radiation to organs outside the treatment field. It is known that the model-based dose algorithm has limitation in calculating the out-of-field doses. This study evaluated the out-of-field dose calculated by the Varian Eclipse treatment planning system (v.11 with AAA algorithm) in realistic treatment plans with the goal of estimating the uncertainties of calculated organ doses. Photon beam phase-space files for TrueBeam linear accelerator were provided by Varian. These were used as incident sources in EGSnrc Monte Carlo simulations of radiation transport through the downstream jaws and MLC. Dynamic movements of the MLC leaves were fully modeled based on treatment plans using IMRT or VMAT techniques. The Monte Carlo calculated out-of-field doses were then compared with those calculated by Eclipse. The dose comparisons were performed for different beam energies and treatment sites, including head-and-neck, lung, and pelvis. For 6 MV (FF/FFF), 10 MV (FF/FFF), and 15 MV (FF) beams, Eclipse underestimated out-of-field local doses by 30%-50% compared with Monte Carlo calculations when the local dose was <1% of prescribed dose. The accuracy of out-of-field dose calculations using Eclipse is improved when collimator jaws were set at the smallest possible aperture for MLC openings. The Eclipse system consistently underestimates out-of-field dose by a factor of 2 for all beam energies studied at the local dose level of less than 1% of prescribed dose. These findings are useful in providing information on the uncertainties of out-of-field organ doses calculated by Eclipse treatment planning system. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

SU-D-207-03: Development of 4D-CBCT Imaging System with Dual Source KV X-Ray Tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, M; Ishihara, Y; Matsuo, Y

Purpose: The purposes of this work are to develop 4D-CBCT imaging system with orthogonal dual source kV X-ray tubes, and to determine the imaging doses from 4D-CBCT scans. Methods: Dual source kV X-ray tubes were used for the 4D-CBCT imaging. The maximum CBCT field of view was 200 mm in diameter and 150 mm in length, and the imaging parameters were 110 kV, 160 mA and 5 ms. The rotational angle was 105°, the rotational speed of the gantry was 1.5°/s, the gantry rotation time was 70 s, and the image acquisition interval was 0.3°. The observed amplitude of infraredmore » marker motion during respiration was used to sort each image into eight respiratory phase bins. The EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc packages were used to simulate kV X-ray dose distributions of 4D-CBCT imaging. The kV X-ray dose distributions were calculated for 9 lung cancer patients based on the planning CT images with dose calculation grid size of 2.5 x 2.5 x 2.5 mm. The dose covering a 2-cc volume of skin (D2cc), defined as the inner 5 mm of the skin surface with the exception of bone structure, was assessed. Results: A moving object was well identified on 4D-CBCT images in a phantom study. Given a gantry rotational angle of 105° and the configuration of kV X-ray imaging subsystems, both kV X-ray fields overlapped at a part of skin surface. The D2cc for the 4D-CBCT scans was in the range 73.8–105.4 mGy. Linear correlation coefficient between the 1000 minus averaged SSD during CBCT scanning and D2cc was −0.65 (with a slope of −0.17) for the 4D-CBCT scans. Conclusion: We have developed 4D-CBCT imaging system with dual source kV X-ray tubes. The total imaging dose with 4D-CBCT scans was up to 105.4 mGy.« less

Measurements and Modeling of Radiation Exposure Due to Solar Particle Events

NASA Astrophysics Data System (ADS)

Beck, P.; Conrad Wp6-Sgb Team

Dose assessment procedures of cosmic radiation to aircraft crew are introduced in most of the European countries according the corresponding European directive and national regulations 96 29 Euratom However the radiation exposure due to solar particle events is still a matter of scientific research Several in-flight measurements were performed during solar storm conditions First models to estimate the exposure due to solar particle events were discussed previously Recently EURADOS European Radiation Dosimetry Group http www eurados org started to coordinate research activities in model improvements for dose assessment of solar particle events The coordinated research is a work package of the European research project CONRAD Coordinated Network for Radiation Dosimetry on complex mixed radiation fields at workplaces Major aim of sub group B of that work package is the validation of models for dose assessment of solar particle events using data from neutron ground level monitors in-flight measurement results obtained during a solar particle event and proton satellite data The paper describes the current status of obtainable solar storm measurements and gives an overview of the existing models for dose assessment of solar particle events in flight altitudes

Modification and validation of an analytical source model for external beam radiotherapy Monte Carlo dose calculations.

PubMed

Davidson, Scott E; Cui, Jing; Kry, Stephen; Deasy, Joseph O; Ibbott, Geoffrey S; Vicic, Milos; White, R Allen; Followill, David S

2016-08-01

A dose calculation tool, which combines the accuracy of the dose planning method (DPM) Monte Carlo code and the versatility of a practical analytical multisource model, which was previously reported has been improved and validated for the Varian 6 and 10 MV linear accelerators (linacs). The calculation tool can be used to calculate doses in advanced clinical application studies. One shortcoming of current clinical trials that report dose from patient plans is the lack of a standardized dose calculation methodology. Because commercial treatment planning systems (TPSs) have their own dose calculation algorithms and the clinical trial participant who uses these systems is responsible for commissioning the beam model, variation exists in the reported calculated dose distributions. Today's modern linac is manufactured to tight specifications so that variability within a linac model is quite low. The expectation is that a single dose calculation tool for a specific linac model can be used to accurately recalculate dose from patient plans that have been submitted to the clinical trial community from any institution. The calculation tool would provide for a more meaningful outcome analysis. The analytical source model was described by a primary point source, a secondary extra-focal source, and a contaminant electron source. Off-axis energy softening and fluence effects were also included. The additions of hyperbolic functions have been incorporated into the model to correct for the changes in output and in electron contamination with field size. A multileaf collimator (MLC) model is included to facilitate phantom and patient dose calculations. An offset to the MLC leaf positions was used to correct for the rudimentary assumed primary point source. Dose calculations of the depth dose and profiles for field sizes 4 × 4 to 40 × 40 cm agree with measurement within 2% of the maximum dose or 2 mm distance to agreement (DTA) for 95% of the data points tested. The model was capable of predicting the depth of the maximum dose within 1 mm. Anthropomorphic phantom benchmark testing of modulated and patterned MLCs treatment plans showed agreement to measurement within 3% in target regions using thermoluminescent dosimeters (TLD). Using radiochromic film normalized to TLD, a gamma criteria of 3% of maximum dose and 2 mm DTA was applied with a pass rate of least 85% in the high dose, high gradient, and low dose regions. Finally, recalculations of patient plans using DPM showed good agreement relative to a commercial TPS when comparing dose volume histograms and 2D dose distributions. A unique analytical source model coupled to the dose planning method Monte Carlo dose calculation code has been modified and validated using basic beam data and anthropomorphic phantom measurement. While this tool can be applied in general use for a particular linac model, specifically it was developed to provide a singular methodology to independently assess treatment plan dose distributions from those clinical institutions participating in National Cancer Institute trials.

SU-E-T-226: Correction of a Standard Model-Based Dose Calculator Using Measurement Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, M; Jiang, S; Lu, W

Purpose: To propose a hybrid method that combines advantages of the model-based and measurement-based method for independent dose calculation. Modeled-based dose calculation, such as collapsed-cone-convolution/superposition (CCCS) or the Monte-Carlo method, models dose deposition in the patient body accurately; however, due to lack of detail knowledge about the linear accelerator (LINAC) head, commissioning for an arbitrary machine is tedious and challenging in case of hardware changes. On the contrary, the measurement-based method characterizes the beam property accurately but lacks the capability of dose disposition modeling in heterogeneous media. Methods: We used a standard CCCS calculator, which is commissioned by published data,more » as the standard model calculator. For a given machine, water phantom measurements were acquired. A set of dose distributions were also calculated using the CCCS for the same setup. The difference between the measurements and the CCCS results were tabulated and used as the commissioning data for a measurement based calculator. Here we used a direct-ray-tracing calculator (ΔDRT). The proposed independent dose calculation consists of the following steps: 1. calculate D-model using CCCS. 2. calculate D-ΔDRT using ΔDRT. 3. combine Results: D=D-model+D-ΔDRT. Results: The hybrid dose calculation was tested on digital phantoms and patient CT data for standard fields and IMRT plan. The results were compared to dose calculated by the treatment planning system (TPS). The agreement of the hybrid and the TPS was within 3%, 3 mm for over 98% of the volume for phantom studies and lung patients. Conclusion: The proposed hybrid method uses the same commissioning data as those for the measurement-based method and can be easily extended to any non-standard LINAC. The results met the accuracy, independence, and simple commissioning criteria for an independent dose calculator.« less

SU-F-T-151: Measurement Evaluation of Skin Dose in Scanning Proton Beam Therapy for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, J; Nichols, E; Strauss, D

Purpose: To measure the skin dose and compare it with the calculated dose from a treatment planning system (TPS) for breast cancer treatment using scanning proton beam therapy (SPBT). Methods: A single en-face-beam SPBT plan was generated by a commercial TPS for two breast cancer patients. The treatment volumes were the entire breasts (218 cc and 1500 cc) prescribed to 50.4 Gy (RBE) in 28 fractions. A range shifter of 5 cm water equivalent thickness was used. The organ at risk (skin) was defined to be 5 mm thick from the surface. The skin doses were measured in water withmore » an ADCL calibrated parallel plate (PP) chamber. The measured data were compared with the values calculated in the TPS. Skin dose calculations can be subject to uncertainties created by the definition of the external contour and the limitations of the correction based algorithms, such as proton convolution superposition. Hence, the external contours were expanded by 0, 3 mm and 1 cm to include additional pixels for dose calculation. In addition, to examine the effects of the cloth gown on the skin dose, the skin dose measurements were conducted with and without gown. Results: On average the measured skin dose was 4% higher than the calculated values. At deeper depths, the measured and calculated doses were in better agreement (< 2%). Large discrepancy occur for the dose calculated without external expansion due to volume averaging. The addition of the gown only increased the measured skin dose by 0.4%. Conclusion: The implemented TPS underestimated the skin dose for breast treatments. Superficial dose calculation without external expansion would result in large errors for SPBT for breast cancer.« less

Human exposure assessment of silver and copper migrating from an antimicrobial nanocoated packaging material into an acidic food simulant.

PubMed

Hannon, Joseph Christopher; Kerry, Joseph P; Cruz-Romero, Malco; Azlin-Hasim, Shafrina; Morris, Michael; Cummins, Enda

2016-09-01

To examine the human exposure to a novel silver and copper nanoparticle (AgNP and CuNP)/polystyrene-polyethylene oxide block copolymer (PS-b-PEO) food packaging coating, the migration of Ag and Cu into 3% acetic acid (3% HAc) food simulant was assessed at 60 °C for 10 days. Significantly lower migration was observed for Ag (0.46 mg/kg food) compared to Cu (0.82 mg/kg food) measured by inductively coupled plasma - atomic emission spectrometry (ICP-AES). In addition, no distinct population of AgNPs or CuNPs were observed in 3% HAc by nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). The predicted human exposure to Ag and Cu was used to calculate a margin of exposure (MOE) for ionic species of Ag and Cu, which indicated the safe use of the food packaging in a hypothetical scenario (e.g. as fruit juice packaging). While migration exceeded regulatory limits, the calculated MOE suggests current migration limits may be conservative for specific nano-packaging applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

waterData--An R package for retrieval, analysis, and anomaly calculation of daily hydrologic time series data, version 1.0

USGS Publications Warehouse

Ryberg, Karen R.; Vecchia, Aldo V.

2012-01-01

Hydrologic time series data and associated anomalies (multiple components of the original time series representing variability at longer-term and shorter-term time scales) are useful for modeling trends in hydrologic variables, such as streamflow, and for modeling water-quality constituents. An R package, called waterData, has been developed for importing daily hydrologic time series data from U.S. Geological Survey streamgages into the R programming environment. In addition to streamflow, data retrieval may include gage height and continuous physical property data, such as specific conductance, pH, water temperature, turbidity, and dissolved oxygen. The package allows for importing daily hydrologic data into R, plotting the data, fixing common data problems, summarizing the data, and the calculation and graphical presentation of anomalies.

Improving spot-scanning proton therapy patient specific quality assurance with HPlusQA, a second-check dose calculation engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackin, Dennis; Li, Yupeng; Taylor, Michael B.

Purpose: The purpose of this study was to validate the use of HPlusQA, spot-scanning proton therapy (SSPT) dose calculation software developed at The University of Texas MD Anderson Cancer Center, as second-check dose calculation software for patient-specific quality assurance (PSQA). The authors also showed how HPlusQA can be used within the current PSQA framework.Methods: The authors compared the dose calculations of HPlusQA and the Eclipse treatment planning system with 106 planar dose measurements made as part of PSQA. To determine the relative performance and the degree of correlation between HPlusQA and Eclipse, the authors compared calculated with measured point doses.more » Then, to determine how well HPlusQA can predict when the comparisons between Eclipse calculations and the measured dose will exceed tolerance levels, the authors compared gamma index scores for HPlusQA versus Eclipse with those of measured doses versus Eclipse. The authors introduce the αβγ transformation as a way to more easily compare gamma scores.Results: The authors compared measured and calculated dose planes using the relative depth, z/R × 100%, where z is the depth of the measurement and R is the proton beam range. For relative depths than less than 80%, both Eclipse and HPlusQA calculations were within 2 cGy of dose measurements on average. When the relative depth was greater than 80%, the agreement between the calculations and measurements fell to 4 cGy. For relative depths less than 10%, the Eclipse and HPlusQA dose discrepancies showed a negative correlation, −0.21. Otherwise, the correlation between the dose discrepancies was positive and as large as 0.6. For the dose planes in this study, HPlusQA correctly predicted when Eclipse had and had not calculated the dose to within tolerance 92% and 79% of the time, respectively. In 4 of 106 cases, HPlusQA failed to predict when the comparison between measurement and Eclipse's calculation had exceeded the tolerance levels of 3% for dose and 3 mm for distance-to-agreement.Conclusions: The authors found HPlusQA to be reasonably effective (79%± 10%) in determining when the comparison between measured dose planes and the dose planes calculated by the Eclipse treatment planning system had exceeded the acceptable tolerance levels. When used as described in this study, HPlusQA can reduce the need for patient specific quality assurance measurements by 64%. The authors believe that the use of HPlusQA as a dose calculation second check can increase the efficiency and effectiveness of the QA process.« less

Direct NOE simulation from long MD trajectories.

PubMed

Chalmers, G; Glushka, J N; Foley, B L; Woods, R J; Prestegard, J H

2016-04-01

A software package, MD2NOE, is presented which calculates Nuclear Overhauser Effect (NOE) build-up curves directly from molecular dynamics (MD) trajectories. It differs from traditional approaches in that it calculates correlation functions directly from the trajectory instead of extracting inverse sixth power distance terms as an intermediate step in calculating NOEs. This is particularly important for molecules that sample conformational states on a timescale similar to molecular reorientation. The package is tested on sucrose and results are shown to differ in small but significant ways from those calculated using an inverse sixth power assumption. Results are also compared to experiment and found to be in reasonable agreement despite an expected underestimation of water viscosity by the water model selected. Copyright © 2016 Elsevier Inc. All rights reserved.

Radon-222 from different sources of water and the assessment of health hazard.

PubMed

Ademola, Janet A; Ojeniran, Oluwaferanmi R

2017-02-01

Water samples collected from different sources were analysed for radon concentrations in order to evaluate the health effect associated with radon in water. The radon concentrations were in the range of 3.56-98.57, 0.88-25.49, 0.73-1.35 and 0.24-1.03 Bq.L -1 for borehole, well, packaged and utility water, respectively. Samples from boreholes had the highest radon concentrations with about 67% being higher than the threshold value of 11.1 Bq.L -1 recommended by the USEPA. The mean annual effective dose (AED) due to ingestion for adult, child and infant ranged from 8.71 × 10 -3 to 0.831 mSv.y -1 for the different sources. The mean AED calculated for consuming water from boreholes and wells for the three age groups were higher than the recommended reference dose level of 0.1 mSv.y -1 . The mean AED due to inhalation of radon in drinking water was negligible, ranging from 0.13 to 6.20 μSv.y -1 . The health burden associated with radon in water in the study is through ingestion of water directly from boreholes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, D; O’Connell, D; Lamb, J

Purpose: To demonstrate real-time dose calculation of free-breathing MRI guided Co−60 treatments, using a motion model and Monte-Carlo dose calculation to accurately account for the interplay between irregular breathing motion and an IMRT delivery. Methods: ViewRay Co-60 dose distributions were optimized on ITVs contoured from free-breathing CT images of lung cancer patients. Each treatment plan was separated into 0.25s segments, accounting for the MLC positions and beam angles at each time point. A voxel-specific motion model derived from multiple fast-helical free-breathing CTs and deformable registration was calculated for each patient. 3D images for every 0.25s of a simulated treatment weremore » generated in real time, here using a bellows signal as a surrogate to accurately account for breathing irregularities. Monte-Carlo dose calculation was performed every 0.25s of the treatment, with the number of histories in each calculation scaled to give an overall 1% statistical uncertainty. Each dose calculation was deformed back to the reference image using the motion model and accumulated. The static and real-time dose calculations were compared. Results: Image generation was performed in real time at 4 frames per second (GPU). Monte-Carlo dose calculation was performed at approximately 1frame per second (CPU), giving a total calculation time of approximately 30 minutes per treatment. Results show both cold- and hot-spots in and around the ITV, and increased dose to contralateral lung as the tumor moves in and out of the beam during treatment. Conclusion: An accurate motion model combined with a fast Monte-Carlo dose calculation allows almost real-time dose calculation of a free-breathing treatment. When combined with sagittal 2D-cine-mode MRI during treatment to update the motion model in real time, this will allow the true delivered dose of a treatment to be calculated, providing a useful tool for adaptive planning and assessing the effectiveness of gated treatments.« less

A Preliminary Performance Assessment for Salt Disposal of High-Level Nuclear Waste - 12173

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Joon H.; Clayton, Daniel; Jove-Colon, Carlos

2012-07-01

A salt repository is one of the four geologic media currently under study by the U.S. DOE Office of Nuclear Energy to support the development of a long-term strategy for geologic disposal of commercial used nuclear fuel (UNF) and high-level radioactive waste (HLW). The immediate goal of the generic salt repository study is to develop the necessary modeling tools to evaluate and improve the understanding of the repository system response and processes relevant to long-term disposal of UNF and HLW in a salt formation. The current phase of this study considers representative geologic settings and features adopted from previous studiesmore » for salt repository sites. For the reference scenario, the brine flow rates in the repository and underlying interbeds are very low, and transport of radionuclides in the transport pathways is dominated by diffusion and greatly retarded by sorption on the interbed filling materials. I-129 is the dominant annual dose contributor at the hypothetical accessible environment, but the calculated mean annual dose is negligibly small. For the human intrusion (or disturbed) scenario, the mean mass release rate and mean annual dose histories are very different from those for the reference scenario. Actinides including Pu-239, Pu-242 and Np-237 are major annual dose contributors, and the calculated peak mean annual dose is acceptably low. A performance assessment model for a generic salt repository has been developed incorporating, where applicable, representative geologic settings and features adopted from literature data for salt repository sites. The conceptual model and scenario for radionuclide release and transport from a salt repository were developed utilizing literature data. The salt GDS model was developed in a probabilistic analysis framework. The preliminary performance analysis for demonstration of model capability is for an isothermal condition at the ambient temperature for the near field. The capability demonstration emphasizes key attributes of a salt repository that are potentially important to the long-term safe disposal of UNF and HLW. The analysis presents and discusses the results showing repository responses to different radionuclide release scenarios (undisturbed and human intrusion). For the reference (or nominal or undisturbed) scenario, the brine flow rates in the repository and underlying interbeds are very low, and transport of radionuclides in the transport pathways is dominated by diffusion and greatly retarded by sorption on the interbed filling materials. I-129 (non-sorbing and unlimited solubility with a very long half-life) is the dominant annual dose contributor at the hypothetical accessible environment, but the calculated mean annual dose is negligibly small that there is no meaningful consequence for the repository performance. For the human intrusion (or disturbed) scenario analysis, the mean mass release rate and mean annual dose histories are very different from those for the reference scenario analysis. Compared to the reference scenario, the relative annual dose contributions by soluble, non-sorbing fission products, particularly I-129, are much lower than by actinides including Pu-239, Pu-242 and Np-237. The lower relative mean annual dose contributions by the fission product radionuclides are due to their lower total inventory available for release (i.e., up to five affected waste packages), and the higher mean annual doses by the actinides are the outcome of the direct release of the radionuclides into the overlying aquifer having high water flow rates, thereby resulting in an early arrival of higher concentrations of the radionuclides at the biosphere drinking water well prior to their significant decay. The salt GDS model analysis has also identified the following future recommendations and/or knowledge gaps to improve and enhance the confidence of the future repository performance analysis. - Repository thermal loading by UNF and HLW, and the effect on the engineered barrier and near-field performance. - Closure and consolidation of salt rocks by creep deformation under the influence of thermal perturbation, and the effect on the engineered barrier and near-field performance. - Brine migration and radionuclide transport under the influence of thermal perturbation in generic salt repository environment, and the effect on the engineered barrier and near-field performance and far-field performance. - Near-field geochemistry and radionuclide mobility in generic salt repository environment (high ionic strength brines, elevated temperatures and chemically reducing condition). - Degradation of engineer barrier components (waste package, waste canister, waste forms, etc.) in a generic salt repository environment (high ionic strength brines, elevated temperatures and chemically reducing condition). - Waste stream types and inventory estimates, particularly for reprocessing high-level waste. (authors)« less

A point kernel algorithm for microbeam radiation therapy

NASA Astrophysics Data System (ADS)

Debus, Charlotte; Oelfke, Uwe; Bartzsch, Stefan

2017-11-01

Microbeam radiation therapy (MRT) is a treatment approach in radiation therapy where the treatment field is spatially fractionated into arrays of a few tens of micrometre wide planar beams of unusually high peak doses separated by low dose regions of several hundred micrometre width. In preclinical studies, this treatment approach has proven to spare normal tissue more effectively than conventional radiation therapy, while being equally efficient in tumour control. So far dose calculations in MRT, a prerequisite for future clinical applications are based on Monte Carlo simulations. However, they are computationally expensive, since scoring volumes have to be small. In this article a kernel based dose calculation algorithm is presented that splits the calculation into photon and electron mediated energy transport, and performs the calculation of peak and valley doses in typical MRT treatment fields within a few minutes. Kernels are analytically calculated depending on the energy spectrum and material composition. In various homogeneous materials peak, valley doses and microbeam profiles are calculated and compared to Monte Carlo simulations. For a microbeam exposure of an anthropomorphic head phantom calculated dose values are compared to measurements and Monte Carlo calculations. Except for regions close to material interfaces calculated peak dose values match Monte Carlo results within 4% and valley dose values within 8% deviation. No significant differences are observed between profiles calculated by the kernel algorithm and Monte Carlo simulations. Measurements in the head phantom agree within 4% in the peak and within 10% in the valley region. The presented algorithm is attached to the treatment planning platform VIRTUOS. It was and is used for dose calculations in preclinical and pet-clinical trials at the biomedical beamline ID17 of the European synchrotron radiation facility in Grenoble, France.

Teaching Science and Mathematics Subjects Using the Excel Spreadsheet Package

ERIC Educational Resources Information Center

Ibrahim, Dogan

2009-01-01

The teaching of scientific subjects usually require laboratories where students can put the theory they have learned into practice. Traditionally, electronic programmable calculators, dedicated software, or expensive software simulation packages, such as MATLAB have been used to simulate scientific experiments. Recently, spreadsheet programs have…

Implementation of radiation shielding calculation methods. Volume 1: Synopsis of methods and summary of results

NASA Technical Reports Server (NTRS)

Capo, M. A.; Disney, R. K.

1971-01-01

The work performed in the following areas is summarized: (1) Analysis of Realistic nuclear-propelled vehicle was analyzed using the Marshall Space Flight Center computer code package. This code package includes one and two dimensional discrete ordinate transport, point kernel, and single scatter techniques, as well as cross section preparation and data processing codes, (2) Techniques were developed to improve the automated data transfer in the coupled computation method of the computer code package and improve the utilization of this code package on the Univac-1108 computer system. (3) The MSFC master data libraries were updated.

Determination of dose distributions and parameter sensitivity. Hanford Environmental Dose Reconstruction Project; dose code recovery activities; Calculation 005

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, B.A.; Farris, W.T.; Simpson, J.C.

1992-12-01

A series of scoping calculations has been undertaken to evaluate the absolute and relative contribution of different radionuclides and exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 005) examined the contributions of numerous parameters to the uncertainty distribution of doses calculated for environmental exposures and accumulation in foods. This study builds on the work initiated in the first scoping study of iodine in cow`s milk and the third scoping study, which added additional pathways. Addressed in this calculation were the contributions to thyroid dose ofmore » infants from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows` milk from Feeding Regime 1 as described in Calculation 001.« less

Dose calculation of dynamic trajectory radiotherapy using Monte Carlo.

PubMed

Manser, P; Frauchiger, D; Frei, D; Volken, W; Terribilini, D; Fix, M K

2018-04-06

Using volumetric modulated arc therapy (VMAT) delivery technique gantry position, multi-leaf collimator (MLC) as well as dose rate change dynamically during the application. However, additional components can be dynamically altered throughout the dose delivery such as the collimator or the couch. Thus, the degrees of freedom increase allowing almost arbitrary dynamic trajectories for the beam. While the dose delivery of such dynamic trajectories for linear accelerators is technically possible, there is currently no dose calculation and validation tool available. Thus, the aim of this work is to develop a dose calculation and verification tool for dynamic trajectories using Monte Carlo (MC) methods. The dose calculation for dynamic trajectories is implemented in the previously developed Swiss Monte Carlo Plan (SMCP). SMCP interfaces the treatment planning system Eclipse with a MC dose calculation algorithm and is already able to handle dynamic MLC and gantry rotations. Hence, the additional dynamic components, namely the collimator and the couch, are described similarly to the dynamic MLC by defining data pairs of positions of the dynamic component and the corresponding MU-fractions. For validation purposes, measurements are performed with the Delta4 phantom and film measurements using the developer mode on a TrueBeam linear accelerator. These measured dose distributions are then compared with the corresponding calculations using SMCP. First, simple academic cases applying one-dimensional movements are investigated and second, more complex dynamic trajectories with several simultaneously moving components are compared considering academic cases as well as a clinically motivated prostate case. The dose calculation for dynamic trajectories is successfully implemented into SMCP. The comparisons between the measured and calculated dose distributions for the simple as well as for the more complex situations show an agreement which is generally within 3% of the maximum dose or 3mm. The required computation time for the dose calculation remains the same when the additional dynamic moving components are included. The results obtained for the dose comparisons for simple and complex situations suggest that the extended SMCP is an accurate dose calculation and efficient verification tool for dynamic trajectory radiotherapy. This work was supported by Varian Medical Systems. Copyright © 2018. Published by Elsevier GmbH.

SU-E-T-381: Evaluation of Calculated Dose Accuracy for Organs-At-Risk Located at Out-Of-Field in a Commercial Treatment Planning System for High Energy Photon Beams Produced From TrueBeam Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L; Ding, G

Purpose: Dose calculation accuracy for the out-of-field dose is important for predicting the dose to the organs-at-risk when they are located outside primary beams. The investigations on evaluating the calculation accuracy of treatment planning systems (TPS) on out-of-field dose in existing publications have focused on low energy (6MV) photon. This study evaluates out-of-field dose calculation accuracy of AAA algorithm for 15MV high energy photon beams. Methods: We used the EGSnrc Monte Carlo (MC) codes to evaluate the AAA algorithm in Varian Eclipse TPS (v.11). The incident beams start with validated Varian phase-space sources for a TrueBeam linac equipped with Millenniummore » 120 MLC. Dose comparisons between using AAA and MC for CT based realistic patient treatment plans using VMAT techniques for prostate and lung were performed and uncertainties of organ dose predicted by AAA at out-of-field location were evaluated. Results: The results show that AAA calculations under-estimate doses at the dose level of 1% (or less) of prescribed dose for CT based patient treatment plans using VMAT techniques. In regions where dose is only 1% of prescribed dose, although AAA under-estimates the out-of-field dose by 30% relative to the local dose, it is only about 0.3% of prescribed dose. For example, the uncertainties of calculated organ dose to liver or kidney that is located out-of-field is <0.3% of prescribed dose. Conclusion: For 15MV high energy photon beams, very good agreements (<1%) in calculating dose distributions were obtained between AAA and MC. The uncertainty of out-of-field dose calculations predicted by the AAA algorithm for realistic patient VMAT plans is <0.3% of prescribed dose in regions where the dose relative to the prescribed dose is <1%, although the uncertainties can be much larger relative to local doses. For organs-at-risk located at out-of-field, the error of dose predicted by Eclipse using AAA is negligible. This work was conducted in part using the resources of Varian research grant VUMC40590-R.« less

SU-E-T-117: Analysis of the ArcCHECK Dosimetry Gamma Failure Using the 3DVH System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, S; Choi, W; Lee, H

2015-06-15

Purpose: To evaluate gamma analysis failure for the VMAT patient specific QA using ArcCHECK cylindrical phantom. The 3DVH system(Sun Nuclear, FL) was used to analyze the dose difference statistic between measured dose and treatment planning system calculated dose. Methods: Four case of gamma analysis failure were selected retrospectively. Our institution gamma analysis indexes were absolute dose, 3%/3mm and 90%pass rate in the ArcCHECK dosimetry. The collapsed cone convolution superposition (CCCS) dose calculation algorithm for VMAT was used. Dose delivery was performed with Elekta Agility. The A1SL(standard imaging, WI) and cavity plug were used for point dose measurement. Delivery QA plansmore » and images were used for 3DVH Reference data instead of patient plan and image. The measured data of ‘.txt’ file was used for comparison at diodes to acquire a global dose level. The,.acml’ file was used for AC-PDP and to calculated point dose. Results: The global dose of 3DVH was calculated as 1.10 Gy, 1.13, 1.01 and 0.2 Gy respectively. The global dose of 0.2 Gy case was induced by distance discrepancy. The TPS calculated point dose of was 2.33 Gy to 2.77 Gy and 3DVH calculated dose was 2.33 Gy to 2.68 Gy. The maximum dose differences were −2.83% and −3.1% for TPS vs. measured dose and TPS vs. 3DVH calculated respectively in the same case. The difference between measured and 3DVH was 0.1% in that case. The 3DVH gamma pass rate was 98% to 99.7%. Conclusion: We found the TPS calculation error by 3DVH calculation using ArcCHECK measured dose. It seemed that our CCCS algorithm RTP system over estimated at the central region and underestimated scattering at the peripheral diode detector point. The relative gamma analysis and point dose measurement would be recommended for VMAT DQA in the gamma failure case of ArcCHECK dosimetry.« less

Effect of Embolization Material in the Calculation of Dose Deposition in Arteriovenous Malformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

De la Cruz, O. O. Galvan; Moreno-Jimenez, S.; Larraga-Gutierrez, J. M.

2010-12-07

In this work it is studied the impact of the incorporation of high Z materials (embolization material) in the dose calculation for stereotactic radiosurgery treatment for arteriovenous malformations. A statistical analysis is done to establish the variables that may impact in the dose calculation. To perform the comparison pencil beam (PB) and Monte Carlo (MC) calculation algorithms were used. The comparison between both dose calculations shows that PB overestimates the dose deposited. The statistical analysis, for the quantity of patients of the study (20), shows that the variable that may impact in the dose calculation is the volume of themore » high Z material in the arteriovenous malformation. Further studies have to be done to establish the clinical impact with the radiosurgery result.« less

SU-F-T-415: Differences in Lung Sparing in Deep Inspiration Breath-Hold and Free Breathing Breast Plans Calculated in Pinnacle and Monaco

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saenz, D; Stathakis, S

Purpose: Deep inspiration breath-hold (DIBH) is used for left-sided breast radiotherapy to spare the heart and lung. The magnitude of sparing has been shown to be significant. Monte Carlo, furthermore, has the potential to calculate most accurately the dose in the heterogeneous lung medium at the interface with the lung wall. The lung dose was investigated in Monaco to determine the level of sparing relative to that calculated in Pinnacle{sup 3}. Methods: Five patients undergoing DIBH radiotherapy on an Elekta Versa HD linear accelerator in conjunction with the Catalyst C-RAD surface imaging system were planned using Phillips Pinnacle{sup 3}. Freemore » breathing plans were also created to clinically assure a benefit. Both plans were re-calculated in Monaco to determine if there were any significant differences. The mean heart dose, mean left lung, and mean total lung dose were compared in addition to the V20 for left and both lungs. Dose was calculated as dose to medium as well as dose to water with a statistical precision of 0.7%. Results: Mean lung dose was significantly different (p < 0.003) between the two calculations for both DIBH (11.6% higher in Monaco) and free breathing (14.2% higher in Monaco). V20 was also higher in Monaco (p < 0.05) for DIBH (5.7% higher) and free breathing (4.9% higher). The mean heart dose was not significantly different between the dose calculations for either DIBH or free breathing. Results were no more than 0.1% different when calculated as dose to water. Conclusion: The use of Monte Carlo can provide insight on the lung dose for both free breathing and DIBH techniques for whole breast irradiation. While the sparing (dose reductions with DIBH as compared to free breathing) is equivalent for either planning system, the lung doses themselves are higher when calculated with Monaco.« less

Independent Monte-Carlo dose calculation for MLC based CyberKnife radiotherapy

NASA Astrophysics Data System (ADS)

Mackeprang, P.-H.; Vuong, D.; Volken, W.; Henzen, D.; Schmidhalter, D.; Malthaner, M.; Mueller, S.; Frei, D.; Stampanoni, M. F. M.; Dal Pra, A.; Aebersold, D. M.; Fix, M. K.; Manser, P.

2018-01-01

This work aims to develop, implement and validate a Monte Carlo (MC)-based independent dose calculation (IDC) framework to perform patient-specific quality assurance (QA) for multi-leaf collimator (MLC)-based CyberKnife® (Accuray Inc., Sunnyvale, CA) treatment plans. The IDC framework uses an XML-format treatment plan as exported from the treatment planning system (TPS) and DICOM format patient CT data, an MC beam model using phase spaces, CyberKnife MLC beam modifier transport using the EGS++ class library, a beam sampling and coordinate transformation engine and dose scoring using DOSXYZnrc. The framework is validated against dose profiles and depth dose curves of single beams with varying field sizes in a water tank in units of cGy/Monitor Unit and against a 2D dose distribution of a full prostate treatment plan measured with Gafchromic EBT3 (Ashland Advanced Materials, Bridgewater, NJ) film in a homogeneous water-equivalent slab phantom. The film measurement is compared to IDC results by gamma analysis using 2% (global)/2 mm criteria. Further, the dose distribution of the clinical treatment plan in the patient CT is compared to TPS calculation by gamma analysis using the same criteria. Dose profiles from IDC calculation in a homogeneous water phantom agree within 2.3% of the global max dose or 1 mm distance to agreement to measurements for all except the smallest field size. Comparing the film measurement to calculated dose, 99.9% of all voxels pass gamma analysis, comparing dose calculated by the IDC framework to TPS calculated dose for the clinical prostate plan shows 99.0% passing rate. IDC calculated dose is found to be up to 5.6% lower than dose calculated by the TPS in this case near metal fiducial markers. An MC-based modular IDC framework was successfully developed, implemented and validated against measurements and is now available to perform patient-specific QA by IDC.

SU-F-T-142: An Analytical Model to Correct the Aperture Scattered Dose in Clinical Proton Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, B; Liu, S; Zhang, T

2016-06-15

Purpose: Apertures or collimators are used to laterally shape proton beams in double scattering (DS) delivery and to sharpen the penumbra in pencil beam (PB) delivery. However, aperture-scattered dose is not included in the current dose calculations of treatment planning system (TPS). The purpose of this study is to provide a method to correct the aperture-scattered dose based on an analytical model. Methods: A DS beam with a non-divergent aperture was delivered using a single-room proton machine. Dose profiles were measured with an ion-chamber scanning in water and a 2-D ion chamber matrix with solid-water buildup at various depths. Themore » measured doses were considered as the sum of the non-contaminated dose and the aperture-scattered dose. The non-contaminated dose was calculated by TPS and subtracted from the measured dose. Aperture scattered-dose was modeled as a 1D Gaussian distribution. For 2-D fields, to calculate the scatter-dose from all the edges of aperture, a sum of weighted distance was used in the model based on the distance from calculation point to aperture edge. The gamma index was calculated between the measured and calculated dose with and without scatter correction. Results: For a beam with range of 23 cm and aperture size of 20 cm, the contribution of the scatter horn was ∼8% of the total dose at 4 cm depth and diminished to 0 at 15 cm depth. The amplitude of scatter-dose decreased linearly with the depth increase. The 1D gamma index (2%/2 mm) between the calculated and measured profiles increased from 63% to 98% for 4 cm depth and from 83% to 98% at 13 cm depth. The 2D gamma index (2%/2 mm) at 4 cm depth has improved from 78% to 94%. Conclusion: Using the simple analytical method the discrepancy between the measured and calculated dose has significantly improved.« less

SU-F-T-340: Direct Editing of Dose Volume Histograms: Algorithms and a Unified Convex Formulation for Treatment Planning with Dose Constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ungun, B; Stanford University School of Medicine, Stanford, CA; Fu, A

2016-06-15

Purpose: To develop a procedure for including dose constraints in convex programming-based approaches to treatment planning, and to support dynamic modification of such constraints during planning. Methods: We present a mathematical approach that allows mean dose, maximum dose, minimum dose and dose volume (i.e., percentile) constraints to be appended to any convex formulation of an inverse planning problem. The first three constraint types are convex and readily incorporated. Dose volume constraints are not convex, however, so we introduce a convex restriction that is related to CVaR-based approaches previously proposed in the literature. To compensate for the conservatism of this restriction,more » we propose a new two-pass algorithm that solves the restricted problem on a first pass and uses this solution to form exact constraints on a second pass. In another variant, we introduce slack variables for each dose constraint to prevent the problem from becoming infeasible when the user specifies an incompatible set of constraints. We implement the proposed methods in Python using the convex programming package cvxpy in conjunction with the open source convex solvers SCS and ECOS. Results: We show, for several cases taken from the clinic, that our proposed method meets specified constraints (often with margin) when they are feasible. Constraints are met exactly when we use the two-pass method, and infeasible constraints are replaced with the nearest feasible constraint when slacks are used. Finally, we introduce ConRad, a Python-embedded free software package for convex radiation therapy planning. ConRad implements the methods described above and offers a simple interface for specifying prescriptions and dose constraints. Conclusion: This work demonstrates the feasibility of using modifiable dose constraints in a convex formulation, making it practical to guide the treatment planning process with interactively specified dose constraints. This work was supported by the Stanford BioX Graduate Fellowship and NIH Grant 5R01CA176553.« less

Patient‐specific CT dosimetry calculation: a feasibility study

PubMed Central

Xie, Huchen; Cheng, Jason Y.; Ning, Holly; Zhuge, Ying; Miller, Robert W.

2011-01-01

Current estimation of radiation dose from computed tomography (CT) scans on patients has relied on the measurement of Computed Tomography Dose Index (CTDI) in standard cylindrical phantoms, and calculations based on mathematical representations of “standard man”. Radiation dose to both adult and pediatric patients from a CT scan has been a concern, as noted in recent reports. The purpose of this study was to investigate the feasibility of adapting a radiation treatment planning system (RTPS) to provide patient‐specific CT dosimetry. A radiation treatment planning system was modified to calculate patient‐specific CT dose distributions, which can be represented by dose at specific points within an organ of interest, as well as organ dose‐volumes (after image segmentation) for a GE Light Speed Ultra Plus CT scanner. The RTPS calculation algorithm is based on a semi‐empirical, measured correction‐based algorithm, which has been well established in the radiotherapy community. Digital representations of the physical phantoms (virtual phantom) were acquired with the GE CT scanner in axial mode. Thermoluminescent dosimeter (TLDs) measurements in pediatric anthropomorphic phantoms were utilized to validate the dose at specific points within organs of interest relative to RTPS calculations and Monte Carlo simulations of the same virtual phantoms (digital representation). Congruence of the calculated and measured point doses for the same physical anthropomorphic phantom geometry was used to verify the feasibility of the method. The RTPS algorithm can be extended to calculate the organ dose by calculating a dose distribution point‐by‐point for a designated volume. Electron Gamma Shower (EGSnrc) codes for radiation transport calculations developed by National Research Council of Canada (NRCC) were utilized to perform the Monte Carlo (MC) simulation. In general, the RTPS and MC dose calculations are within 10% of the TLD measurements for the infant and child chest scans. With respect to the dose comparisons for the head, the RTPS dose calculations are slightly higher (10%–20%) than the TLD measurements, while the MC results were within 10% of the TLD measurements. The advantage of the algebraic dose calculation engine of the RTPS is a substantially reduced computation time (minutes vs. days) relative to Monte Carlo calculations, as well as providing patient‐specific dose estimation. It also provides the basis for a more elaborate reporting of dosimetric results, such as patient specific organ dose volumes after image segmentation. PACS numbers: 87.55.D‐, 87.57.Q‐, 87.53.Bn, 87.55.K‐ PMID:22089016

Effects of Low-Oxygen Environments on the Radiation Tolerance of the Cabbage Looper Moth (Lepidoptera: Noctuidae).

PubMed

Condon, Catriona H; White, Sabrina; Meagher, Robert L; Jeffers, Laura A; Bailey, Woodward D; Hahn, Daniel A

2017-02-01

Ionizing radiation is used as a phytosanitary treatment to mitigate risks from invasive species associated with trade of fresh fruits and vegetables. Commodity producers prefer to irradiate fresh product stored in modified atmosphere packaging that increases shelf life and delays ripening. However, irradiating insects in low oxygen may increase radiation tolerance, and regulatory agencies are concerned modified atmosphere packaging will decrease efficacy of radiation doses. Here, we examined how irradiation in a series of oxygen conditions (0.1-20.9 kPa O2) alters radiotolerance of larvae and pupae of a model lepidopteran Trichoplusia ni (Hubner) (Diptera: Noctuidae). Irradiating in severe hypoxia (0.1 kPa O2) increased radiation tolerance of insects compared with irradiating in atmospheric oxygen (20.9 kPa O2). Our data show irradiating pharate adult pupae at 600 Gy in moderately severe hypoxia (5 kPa O2) increased adult emergence compared with irradiation in atmospheric oxygen (20.9 kPa O2). Our data also show that in one of the three temporal replicates, irradiating T. ni larvae in moderately severe hypoxia (5 kPa O2) can also increase radiotolerance at an intermediate radiation dose of 100 Gy compared with irradiating in atmospheric oxygen conditions, but not at higher or lower doses. We discuss implications of our results in this model insect for the current generic doses for phytosanitary irradiation, including the recently proposed 250 Gy generic dose for lepidioptera larvae, and temporary restriction on irradiating commodities in modified atmosphere packaging that reduces the atmosphere to < 18 kPa O2. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

TU-D-209-05: Automatic Calculation of Organ and Effective Dose for CBCT and Interventional Fluoroscopic Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Z; Vijayan, S; Oines, A

Purpose: To compare PCXMC and EGSnrc calculated organ and effective radiation doses from cone-beam computed tomography (CBCT) and interventional fluoroscopically-guided procedures using automatic exposure-event grouping. Methods: For CBCT, we used PCXMC20Rotation.exe to automatically calculate the doses and compared the results to those calculated using EGSnrc with the Zubal patient phantom. For interventional procedures, we use the dose tracking system (DTS) which we previously developed to produce a log file of all geometry and exposure parameters for every x-ray pulse during a procedure, and the data in the log file is input into PCXMC and EGSnrc for dose calculation. A MATLABmore » program reads data from the log files and groups similar exposures to reduce calculation time. The definition files are then automatically generated in the format used by PCXMC and EGSnrc. Processing is done at the end of the procedure after all exposures are completed. Results: For the Toshiba Infinix CBCT LCI-Middle-Abdominal protocol, most organ doses calculated with PCXMC20Rotation closely matched those calculated with EGSnrc. The effective doses were 33.77 mSv with PCXMC20Rotation and 32.46 mSv with EGSnrc. For a simulated interventional cardiac procedure, similar close agreement in organ dose was obtained between the two codes; the effective doses were 12.02 mSv with PCXMC and 11.35 mSv with EGSnrc. The calculations can be completed on a PC without manual intervention in less than 15 minutes with PCXMC and in about 10 hours with EGSnrc, depending on the level of data grouping and accuracy desired. Conclusion: Effective dose and most organ doses in CBCT and interventional radiology calculated by PCXMC closely match those calculated by EGSnrc. Data grouping, which can be done automatically, makes the calculation time with PCXMC on a standard PC acceptable. This capability expands the dose information that can be provided by the DTS. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

A Simple Interactive Software Package for Plotting, Animating, and Calculating

ERIC Educational Resources Information Center

Engelhardt, Larry

2012-01-01

We introduce a new open source (free) software package that provides a simple, highly interactive interface for carrying out certain mathematical tasks that are commonly encountered in physics. These tasks include plotting and animating functions, solving systems of coupled algebraic equations, and basic calculus (differentiating and integrating…

SU-E-T-120: Analytic Dose Verification for Patient-Specific Proton Pencil Beam Scanning Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, C; Mah, D

2015-06-15

Purpose: To independently verify the QA dose of proton pencil beam scanning (PBS) plans using an analytic dose calculation model. Methods: An independent proton dose calculation engine is created using the same commissioning measurements as those employed to build our commercially available treatment planning system (TPS). Each proton PBS plan is exported from the TPS in DICOM format and calculated by this independent dose engine in a standard 40 x 40 x 40 cm water tank. This three-dimensional dose grid is then compared with the QA dose calculated by the commercial TPS, using standard Gamma criterion. A total of 18more » measured pristine Bragg peaks, ranging from 100 to 226 MeV, are used in the model. Intermediate proton energies are interpolated. Similarly, optical properties of the spots are measured in air over 15 cm upstream and downstream, and fitted to a second-order polynomial. Multiple Coulomb scattering in water is approximated analytically using Preston and Kohler formula for faster calculation. The effect of range shifters on spot size is modeled with generalized Highland formula. Note that the above formulation approximates multiple Coulomb scattering in water and we therefore chose not use the full Moliere/Hanson form. Results: Initial examination of 3 patient-specific prostate PBS plans shows that agreement exists between 3D dose distributions calculated by the TPS and the independent proton PBS dose calculation engine. Both calculated dose distributions are compared with actual measurements at three different depths per beam and good agreements are again observed. Conclusion: Results here showed that 3D dose distributions calculated by this independent proton PBS dose engine are in good agreement with both TPS calculations and actual measurements. This tool can potentially be used to reduce the amount of different measurement depths required for patient-specific proton PBS QA.« less

Efficient voxel navigation for proton therapy dose calculation in TOPAS and Geant4

NASA Astrophysics Data System (ADS)

Schümann, J.; Paganetti, H.; Shin, J.; Faddegon, B.; Perl, J.

2012-06-01

A key task within all Monte Carlo particle transport codes is ‘navigation’, the calculation to determine at each particle step what volume the particle may be leaving and what volume the particle may be entering. Navigation should be optimized to the specific geometry at hand. For patient dose calculation, this geometry generally involves voxelized computed tomography (CT) data. We investigated the efficiency of navigation algorithms on currently available voxel geometry parameterizations in the Monte Carlo simulation package Geant4: G4VPVParameterisation, G4VNestedParameterisation and G4PhantomParameterisation, the last with and without boundary skipping, a method where neighboring voxels with the same Hounsfield unit are combined into one larger voxel. A fourth parameterization approach (MGHParameterization), developed in-house before the latter two parameterizations became available in Geant4, was also included in this study. All simulations were performed using TOPAS, a tool for particle simulations layered on top of Geant4. Runtime comparisons were made on three distinct patient CT data sets: a head and neck, a liver and a prostate patient. We included an additional version of these three patients where all voxels, including the air voxels outside of the patient, were uniformly set to water in the runtime study. The G4VPVParameterisation offers two optimization options. One option has a 60-150 times slower simulation speed. The other is compatible in speed but requires 15-19 times more memory compared to the other parameterizations. We found the average CPU time used for the simulation relative to G4VNestedParameterisation to be 1.014 for G4PhantomParameterisation without boundary skipping and 1.015 for MGHParameterization. The average runtime ratio for G4PhantomParameterisation with and without boundary skipping for our heterogeneous data was equal to 0.97: 1. The calculated dose distributions agreed with the reference distribution for all but the G4PhantomParameterisation with boundary skipping for the head and neck patient. The maximum memory usage ranged from 0.8 to 1.8 GB depending on the CT volume independent of parameterizations, except for the 15-19 times greater memory usage with the G4VPVParameterisation when using the option with a higher simulation speed. The G4VNestedParameterisation was selected as the preferred choice for the patient geometries and treatment plans studied.

Patient-specific IMRT verification using independent fluence-based dose calculation software: experimental benchmarking and initial clinical experience.

PubMed

Georg, Dietmar; Stock, Markus; Kroupa, Bernhard; Olofsson, Jörgen; Nyholm, Tufve; Ahnesjö, Anders; Karlsson, Mikael

2007-08-21

Experimental methods are commonly used for patient-specific intensity-modulated radiotherapy (IMRT) verification. The purpose of this study was to investigate the accuracy and performance of independent dose calculation software (denoted as 'MUV' (monitor unit verification)) for patient-specific quality assurance (QA). 52 patients receiving step-and-shoot IMRT were considered. IMRT plans were recalculated by the treatment planning systems (TPS) in a dedicated QA phantom, in which an experimental 1D and 2D verification (0.3 cm(3) ionization chamber; films) was performed. Additionally, an independent dose calculation was performed. The fluence-based algorithm of MUV accounts for collimator transmission, rounded leaf ends, tongue-and-groove effect, backscatter to the monitor chamber and scatter from the flattening filter. The dose calculation utilizes a pencil beam model based on a beam quality index. DICOM RT files from patient plans, exported from the TPS, were directly used as patient-specific input data in MUV. For composite IMRT plans, average deviations in the high dose region between ionization chamber measurements and point dose calculations performed with the TPS and MUV were 1.6 +/- 1.2% and 0.5 +/- 1.1% (1 S.D.). The dose deviations between MUV and TPS slightly depended on the distance from the isocentre position. For individual intensity-modulated beams (total 367), an average deviation of 1.1 +/- 2.9% was determined between calculations performed with the TPS and with MUV, with maximum deviations up to 14%. However, absolute dose deviations were mostly less than 3 cGy. Based on the current results, we aim to apply a confidence limit of 3% (with respect to the prescribed dose) or 6 cGy for routine IMRT verification. For off-axis points at distances larger than 5 cm and for low dose regions, we consider 5% dose deviation or 10 cGy acceptable. The time needed for an independent calculation compares very favourably with the net time for an experimental approach. The physical effects modelled in the dose calculation software MUV allow accurate dose calculations in individual verification points. Independent calculations may be used to replace experimental dose verification once the IMRT programme is mature.

Modification and validation of an analytical source model for external beam radiotherapy Monte Carlo dose calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, Scott E., E-mail: sedavids@utmb.edu

Purpose: A dose calculation tool, which combines the accuracy of the dose planning method (DPM) Monte Carlo code and the versatility of a practical analytical multisource model, which was previously reported has been improved and validated for the Varian 6 and 10 MV linear accelerators (linacs). The calculation tool can be used to calculate doses in advanced clinical application studies. One shortcoming of current clinical trials that report dose from patient plans is the lack of a standardized dose calculation methodology. Because commercial treatment planning systems (TPSs) have their own dose calculation algorithms and the clinical trial participant who usesmore » these systems is responsible for commissioning the beam model, variation exists in the reported calculated dose distributions. Today’s modern linac is manufactured to tight specifications so that variability within a linac model is quite low. The expectation is that a single dose calculation tool for a specific linac model can be used to accurately recalculate dose from patient plans that have been submitted to the clinical trial community from any institution. The calculation tool would provide for a more meaningful outcome analysis. Methods: The analytical source model was described by a primary point source, a secondary extra-focal source, and a contaminant electron source. Off-axis energy softening and fluence effects were also included. The additions of hyperbolic functions have been incorporated into the model to correct for the changes in output and in electron contamination with field size. A multileaf collimator (MLC) model is included to facilitate phantom and patient dose calculations. An offset to the MLC leaf positions was used to correct for the rudimentary assumed primary point source. Results: Dose calculations of the depth dose and profiles for field sizes 4 × 4 to 40 × 40 cm agree with measurement within 2% of the maximum dose or 2 mm distance to agreement (DTA) for 95% of the data points tested. The model was capable of predicting the depth of the maximum dose within 1 mm. Anthropomorphic phantom benchmark testing of modulated and patterned MLCs treatment plans showed agreement to measurement within 3% in target regions using thermoluminescent dosimeters (TLD). Using radiochromic film normalized to TLD, a gamma criteria of 3% of maximum dose and 2 mm DTA was applied with a pass rate of least 85% in the high dose, high gradient, and low dose regions. Finally, recalculations of patient plans using DPM showed good agreement relative to a commercial TPS when comparing dose volume histograms and 2D dose distributions. Conclusions: A unique analytical source model coupled to the dose planning method Monte Carlo dose calculation code has been modified and validated using basic beam data and anthropomorphic phantom measurement. While this tool can be applied in general use for a particular linac model, specifically it was developed to provide a singular methodology to independently assess treatment plan dose distributions from those clinical institutions participating in National Cancer Institute trials.« less

Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model

USGS Publications Warehouse

Leake, S.A.; Prudic, David E.

1991-01-01

Removal of ground water by pumping from aquifers may result in compaction of compressible fine-grained beds that are within or adjacent to the aquifers. Compaction of the sediments and resulting land subsidence may be permanent if the head declines result in vertical stresses beyond the previous maximum stress. The process of permanent compaction is not routinely included in simulations of ground-water flow. To simulate storage changes from both elastic and inelastic compaction, a computer program was written for use with the U.S. Geological Survey modular finite-difference ground- water flow model. The new program, the Interbed-Storage Package, is designed to be incorporated into this model. In the Interbed-Storage Package, elastic compaction or expansion is assumed to be proportional to change in head. The constant of proportionality is the product of the skeletal component of elastic specific storage and the thickness of the sediments. Similarly, inelastic compaction is assumed to be proportional to decline in head. The constant of proportionality is the product of the skeletal component of inelastic specific storage and the thickness of the sediments. Storage changes are incorporated into the ground-water flow model by adding an additional term to the right-hand side of the flow equation. Within a model time step, the package appropriately apportions storage changes between elastic and inelastic components on the basis of the relation of simulated head to the previous minimum (preconsolidation) head. Two tests were performed to verify that the package works correctly. The first test compared model-calculated storage and compaction changes to hand-calculated values for a three-dimensional simulation. Model and hand-calculated values were essentially equal. The second test was performed to compare the results of the Interbed-Storage Package with results of the one-dimensional Helm compaction model. This test problem simulated compaction in doubly draining confining beds stressed by head changes in adjacent aquifers. The Interbed-Storage Package and the Helm model computed essentially equal values of compaction. Documentation of the Interbed-Storage Package includes data input instructions, flow charts, narratives, and listings for each of the five modules included in the package. The documentation also includes an appendix describing input instructions and a listing of a computer program for time-variant specified-head boundaries. That package was developed to reduce the amount of data input and output associated with one of the Interbed-Storage Package test problems.

SU-E-T-795: Validations of Dose Calculation Accuracy of Acuros BV in High-Dose-Rate (HDR) Brachytherapy with a Shielded Cylinder Applicator Using Monte Carlo Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y; Department of Engineering Physics, Tsinghua University, Beijing; Tian, Z

Purpose: Acuros BV has become available to perform accurate dose calculations in high-dose-rate (HDR) brachytherapy with phantom heterogeneity considered by solving the Boltzmann transport equation. In this work, we performed validation studies regarding the dose calculation accuracy of Acuros BV in cases with a shielded cylinder applicator using Monte Carlo (MC) simulations. Methods: Fifteen cases were considered in our studies, covering five different diameters of the applicator and three different shielding degrees. For each case, a digital phantom was created in Varian BrachyVision with the cylinder applicator inserted in the middle of a large water phantom. A treatment plan withmore » eight dwell positions was generated for these fifteen cases. Dose calculations were performed with Acuros BV. We then generated a voxelized phantom of the same geometry, and the materials were modeled according to the vendor’s specifications. MC dose calculations were then performed using our in-house developed fast MC dose engine for HDR brachytherapy (gBMC) on a GPU platform, which is able to simulate both photon transport and electron transport in a voxelized geometry. A phase-space file for the Ir-192 HDR source was used as a source model for MC simulations. Results: Satisfactory agreements between the dose distributions calculated by Acuros BV and those calculated by gBMC were observed in all cases. Quantitatively, we computed point-wise dose difference within the region that receives a dose higher than 10% of the reference dose, defined to be the dose at 5mm outward away from the applicator surface. The mean dose difference was ∼0.45%–0.51% and the 95-percentile maximum difference was ∼1.24%–1.47%. Conclusion: Acuros BV is able to accurately perform dose calculations in HDR brachytherapy with a shielded cylinder applicator.« less

[Packaging: the guarantee of medicinal quality].

PubMed

Chaumeil, J-C

2003-01-01

Primary packaging guarantees the pharmaceutical quality of the medicinal preparation received by the patient. Glass bottles containing parenteral solutions for example ensure that sterility, quality and optimal stability are preserved until administration. Recent innovations in materials research has lead to improvements in parenteral infusions. Multicompartmental bags, allowing extemporaneous mixtures without opening the container, constitute an extremely beneficial advance for the patient, allowing administration of mixtures with solutions and emulsions which would be unstable if stored. Metered dose pressurized inhalers are an excellent example of drug administration devices designed specifically to ensure quality and bioavailability. These examples illustrate the important role of primary packaging and demonstrate the usefulness of research and development in this area.

SU-G-BRA-14: Dose in a Rigidly Moving Phantom with Jaw and MLC Compensation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, E; Lucas, D

Purpose: To validate dose calculation for a rigidly moving object with jaw motion and MLC shifts to compensate for the motion in a TomoTherapy™ treatment delivery. Methods: An off-line version of the TomoTherapy dose calculator was extended to perform dose calculations for rigidly moving objects. A variety of motion traces were added to treatment delivery plans, along with corresponding jaw compensation and MLC shift compensation profiles. Jaw compensation profiles were calculated by shifting the jaws such that the center of the treatment beam moved by an amount equal to the motion in the longitudinal direction. Similarly, MLC compensation profiles weremore » calculated by shifting the MLC leaves by an amount that most closely matched the motion in the transverse direction. The same jaw and MLC compensation profiles were used during simulated treatment deliveries on a TomoTherapy system, and film measurements were obtained in a rigidly moving phantom. Results: The off-line TomoTherapy dose calculator accurately predicted dose profiles for a rigidly moving phantom along with jaw motion and MLC shifts to compensate for the motion. Calculations matched film measurements to within 2%/1 mm. Jaw and MLC compensation substantially reduced the discrepancy between the delivered dose distribution and the calculated dose with no motion. For axial motion, the compensated dose matched the no-motion dose within 2%/1mm. For transverse motion, the dose matched within 2%/3mm (approximately half the width of an MLC leaf). Conclusion: The off-line TomoTherapy dose calculator accurately computes dose delivered to a rigidly moving object, and accurately models the impact of moving the jaws and shifting the MLC leaf patterns to compensate for the motion. Jaw tracking and MLC leaf shifting can effectively compensate for the dosimetric impact of motion during a TomoTherapy treatment delivery.« less

Dose equivalent rate constants and barrier transmission data for nuclear medicine facility dose calculations and shielding design.

PubMed

Kusano, Maggie; Caldwell, Curtis B

2014-07-01

A primary goal of nuclear medicine facility design is to keep public and worker radiation doses As Low As Reasonably Achievable (ALARA). To estimate dose and shielding requirements, one needs to know both the dose equivalent rate constants for soft tissue and barrier transmission factors (TFs) for all radionuclides of interest. Dose equivalent rate constants are most commonly calculated using published air kerma or exposure rate constants, while transmission factors are most commonly calculated using published tenth-value layers (TVLs). Values can be calculated more accurately using the radionuclide's photon emission spectrum and the physical properties of lead, concrete, and/or tissue at these energies. These calculations may be non-trivial due to the polyenergetic nature of the radionuclides used in nuclear medicine. In this paper, the effects of dose equivalent rate constant and transmission factor on nuclear medicine dose and shielding calculations are investigated, and new values based on up-to-date nuclear data and thresholds specific to nuclear medicine are proposed. To facilitate practical use, transmission curves were fitted to the three-parameter Archer equation. Finally, the results of this work were applied to the design of a sample nuclear medicine facility and compared to doses calculated using common methods to investigate the effects of these values on dose estimates and shielding decisions. Dose equivalent rate constants generally agreed well with those derived from the literature with the exception of those from NCRP 124. Depending on the situation, Archer fit TFs could be significantly more accurate than TVL-based TFs. These results were reflected in the sample shielding problem, with unshielded dose estimates agreeing well, with the exception of those based on NCRP 124, and Archer fit TFs providing a more accurate alternative to TVL TFs and a simpler alternative to full spectral-based calculations. The data provided by this paper should assist in improving the accuracy and tractability of dose and shielding calculations for nuclear medicine facility design.

Radiation-stability of smectite.

PubMed

Sorieul, Stéphanie; Allard, Thierry; Wang, Lumin M; Grambin-Lapeyre, Caroline; Lian, Jie; Calas, Georges; Ewings, Rodney C

2008-11-15

The safety assessment of geological repositories for high-level nuclear waste and spent nuclear fuel requires an understanding of the response of materials to high temperatures and intense radiation fields. Clays, such as smectite, have been proposed as backfill material around waste packages, but their response to intense radiation from short-lived fission products and alpha decay of sorbed actinides remains poorly understood. Cumulative doses may amorphize clays and may alter their properties of sorption, swelling, or water retention. We describe the amorphization of smectites induced by electron and heavy ion irradiations to simulate ionizing radiation and alpha recoil nuclei, respectively. A new "bell-shaped" evolution of the amorphization dose with temperature has been determined. The maximum dose for amorphization occurs at about 300-400 degrees C, showing that temperature-induced dehydroxylation enhances amorphization. The exact shape of the bell-shaped curves depends on the interlayer cation. At ambient temperature, ionizing radiation and alpha-decay events do not show the same efficiency. The former results in amorphization at doses between 10(10)-10(11) Gy which are greater than the total radiation dose expected for radioactive waste over 10(6) years. In contrast, alpha-decay events amorphize clays at doses as low as 0.13-0.16 displacements per atom, i.e. doses consistent with nuclear waste accumulated over approximately 1000 yrs. However, the limited penetration of alpha particles and recoil nuclei, in the 100 nm - 20 microm range, will minimize damage. Clays will not be amorphized unless the waste package is breached and released actinides are heavily sorbed onto the clay overpack.

Rapid Acute Dose Assessment Using MCNP6

NASA Astrophysics Data System (ADS)

Owens, Andrew Steven

Acute radiation doses due to physical contact with a high-activity radioactive source have proven to be an occupational hazard. Multiple radiation injuries have been reported due to manipulating a radioactive source with bare hands or by placing a radioactive source inside a shirt or pants pocket. An effort to reconstruct the radiation dose must be performed to properly assess and medically manage the potential biological effects from such doses. Using the reference computational phantoms defined by the International Commission on Radiological Protection (ICRP) and the Monte Carlo N-Particle transport code (MCNP6), dose rate coefficients are calculated to assess doses for common acute doses due to beta and photon radiation sources. The research investigates doses due to having a radioactive source in either a breast pocket or pants back pocket. The dose rate coefficients are calculated for discrete energies and can be used to interpolate for any given energy of photon or beta emission. The dose rate coefficients allow for quick calculation of whole-body dose, organ dose, and/or skin dose if the source, activity, and time of exposure are known. Doses are calculated with the dose rate coefficients and compared to results from the International Atomic Energy Agency (IAEA) reports from accidents that occurred in Gilan, Iran and Yanango, Peru. Skin and organ doses calculated with the dose rate coefficients appear to agree, but there is a large discrepancy when comparing whole-body doses assessed using biodosimetry and whole-body doses assessed using the dose rate coefficients.

SU-F-T-428: An Optimization-Based Commissioning Tool for Finite Size Pencil Beam Dose Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y; Tian, Z; Song, T

Purpose: Finite size pencil beam (FSPB) algorithms are commonly used to pre-calculate the beamlet dose distribution for IMRT treatment planning. FSPB commissioning, which usually requires fine tuning of the FSPB kernel parameters, is crucial to the dose calculation accuracy and hence the plan quality. Yet due to the large number of beamlets, FSPB commissioning could be very tedious. This abstract reports an optimization-based FSPB commissioning tool we have developed in MatLab to facilitate the commissioning. Methods: A FSPB dose kernel generally contains two types of parameters: the profile parameters determining the dose kernel shape, and a 2D scaling factors accountingmore » for the longitudinal and off-axis corrections. The former were fitted using the penumbra of a reference broad beam’s dose profile with Levenberg-Marquardt algorithm. Since the dose distribution of a broad beam is simply a linear superposition of the dose kernel of each beamlet calculated with the fitted profile parameters and scaled using the scaling factors, these factors could be determined by solving an optimization problem which minimizes the discrepancies between the calculated dose of broad beams and the reference dose. Results: We have commissioned a FSPB algorithm for three linac photon beams (6MV, 15MV and 6MVFFF). Dose of four field sizes (6*6cm2, 10*10cm2, 15*15cm2 and 20*20cm2) were calculated and compared with the reference dose exported from Eclipse TPS system. For depth dose curves, the differences are less than 1% of maximum dose after maximum dose depth for most cases. For lateral dose profiles, the differences are less than 2% of central dose at inner-beam regions. The differences of the output factors are within 1% for all the three beams. Conclusion: We have developed an optimization-based commissioning tool for FSPB algorithms to facilitate the commissioning, providing sufficient accuracy of beamlet dose calculation for IMRT optimization.« less

TU-H-CAMPUS-IeP1-05: A Framework for the Analytic Calculation of Patient-Specific Dose Distribution Due to CBCT Scan for IGRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youn, H; Jeon, H; Nam, J

Purpose: To investigate the feasibility of an analytic framework to estimate patients’ absorbed dose distribution owing to daily cone-beam CT scan for image-guided radiation treatment. Methods: To compute total absorbed dose distribution, we separated the framework into primary and scattered dose calculations. Using the source parameters such as voltage, current, and bowtie filtration, for the primary dose calculation, we simulated the forward projection from the source to each voxel of an imaging object including some inhomogeneous inserts. Then we calculated the primary absorbed dose at each voxel based on the absorption probability deduced from the HU values and Beer’s law.more » In sequence, all voxels constructing the phantom were regarded as secondary sources to radiate scattered photons for scattered dose calculation. Details of forward projection were identical to that of the previous step. The secondary source intensities were given by using scatter-to- primary ratios provided by NIST. In addition, we compared the analytically calculated dose distribution with their Monte Carlo simulation results. Results: The suggested framework for absorbed dose estimation successfully provided the primary and secondary dose distributions of the phantom. Moreover, our analytic dose calculations and Monte Carlo calculations were well agreed each other even near the inhomogeneous inserts. Conclusion: This work indicated that our framework can be an effective monitor to estimate a patient’s exposure owing to cone-beam CT scan for image-guided radiation treatment. Therefore, we expected that the patient’s over-exposure during IGRT might be prevented by our framework.« less

The fastclime Package for Linear Programming and Large-Scale Precision Matrix Estimation in R.

PubMed

Pang, Haotian; Liu, Han; Vanderbei, Robert

2014-02-01

We develop an R package fastclime for solving a family of regularized linear programming (LP) problems. Our package efficiently implements the parametric simplex algorithm, which provides a scalable and sophisticated tool for solving large-scale linear programs. As an illustrative example, one use of our LP solver is to implement an important sparse precision matrix estimation method called CLIME (Constrained L 1 Minimization Estimator). Compared with existing packages for this problem such as clime and flare, our package has three advantages: (1) it efficiently calculates the full piecewise-linear regularization path; (2) it provides an accurate dual certificate as stopping criterion; (3) it is completely coded in C and is highly portable. This package is designed to be useful to statisticians and machine learning researchers for solving a wide range of problems.

User Guide for GoldSim Model to Calculate PA/CA Doses and Limits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, F.

2016-10-31

A model to calculate doses for solid waste disposal at the Savannah River Site (SRS) and corresponding disposal limits has been developed using the GoldSim commercial software. The model implements the dose calculations documented in SRNL-STI-2015-00056, Rev. 0 “Dose Calculation Methodology and Data for Solid Waste Performance Assessment (PA) and Composite Analysis (CA) at the Savannah River Site”.

Monte Carlo dose calculations of beta-emitting sources for intravascular brachytherapy: a comparison between EGS4, EGSnrc, and MCNP.

PubMed

Wang, R; Li, X A

2001-02-01

The dose parameters for the beta-particle emitting 90Sr/90Y source for intravascular brachytherapy (IVBT) have been calculated by different investigators. At a distant distance from the source, noticeable differences are seen in these parameters calculated using different Monte Carlo codes. The purpose of this work is to quantify as well as to understand these differences. We have compared a series of calculations using an EGS4, an EGSnrc, and the MCNP Monte Carlo codes. Data calculated and compared include the depth dose curve for a broad parallel beam of electrons, and radial dose distributions for point electron sources (monoenergetic or polyenergetic) and for a real 90Sr/90Y source. For the 90Sr/90Y source, the doses at the reference position (2 mm radial distance) calculated by the three code agree within 2%. However, the differences between the dose calculated by the three codes can be over 20% in the radial distance range interested in IVBT. The difference increases with radial distance from source, and reaches 30% at the tail of dose curve. These differences may be partially attributed to the different multiple scattering theories and Monte Carlo models for electron transport adopted in these three codes. Doses calculated by the EGSnrc code are more accurate than those by the EGS4. The two calculations agree within 5% for radial distance <6 mm.

Dosimetric comparison of lung stereotactic body radiotherapy treatment plans using averaged computed tomography and end-exhalation computed tomography images: Evaluation of the effect of different dose-calculation algorithms and prescription methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitsuyoshi, Takamasa; Nakamura, Mitsuhiro, E-mail: m_nkmr@kuhp.kyoto-u.ac.jp; Matsuo, Yukinori

The purpose of this article is to quantitatively evaluate differences in dose distributions calculated using various computed tomography (CT) datasets, dose-calculation algorithms, and prescription methods in stereotactic body radiotherapy (SBRT) for patients with early-stage lung cancer. Data on 29 patients with early-stage lung cancer treated with SBRT were retrospectively analyzed. Averaged CT (Ave-CT) and expiratory CT (Ex-CT) images were reconstructed for each patient using 4-dimensional CT data. Dose distributions were initially calculated using the Ave-CT images and recalculated (in the same monitor units [MUs]) by employing Ex-CT images with the same beam arrangements. The dose-volume parameters, including D{sub 95}, D{submore » 90}, D{sub 50}, and D{sub 2} of the planning target volume (PTV), were compared between the 2 image sets. To explore the influence of dose-calculation algorithms and prescription methods on the differences in dose distributions evident between Ave-CT and Ex-CT images, we calculated dose distributions using the following 3 different algorithms: x-ray Voxel Monte Carlo (XVMC), Acuros XB (AXB), and the anisotropic analytical algorithm (AAA). We also used 2 different dose-prescription methods; the isocenter prescription and the PTV periphery prescription methods. All differences in PTV dose-volume parameters calculated using Ave-CT and Ex-CT data were within 3 percentage points (%pts) employing the isocenter prescription method, and within 1.5%pts using the PTV periphery prescription method, irrespective of which of the 3 algorithms (XVMC, AXB, and AAA) was employed. The frequencies of dose-volume parameters differing by >1%pt when the XVMC and AXB were used were greater than those associated with the use of the AAA, regardless of the dose-prescription method employed. All differences in PTV dose-volume parameters calculated using Ave-CT and Ex-CT data on patients who underwent lung SBRT were within 3%pts, regardless of the dose-calculation algorithm or the dose-prescription method employed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, R; Tian, L; Ge, H

Purpose: To evaluate the dosimetry of microscopic disease (MD) region of lung cancer in stereotactic body radiation therapy (SBRT). Methods: For simplicity, we assume organ moves along one dimension. The probability distribution function of tumor position was calculated according to the breathing cycle. The dose to the MD region was obtained through accumulating the treatment planning system calculated doses at different positions in a breathing cycle. A phantom experiment was then conducted to validate the calculated results using a motion phantom (The CIRS ‘Dynamic’ Thorax Phantom). The simulated breathing pattern used a cos4(x) curve with an amplitude of 10mm. Amore » 3-D conformal 7-field plan with 6X energy was created and the dose was calculated in the average intensity projection (AIP) simulation CT images. Both films (EBT2) and optically stimulated luminescence (OSL) detectors were inserted in the target of the phantom to measure the dose during radiation delivery (Varian Truebeam) and results were compared to planning dose parameters. Results: The Gamma analysis (3%/3mm) between measured dose using EBT2 film and calculated dose using AIP was 80.5%, indicating substantial dosimetric differences. While the Gamma analysis (3%/3mm) between measured dose using EBT2 and accumulated dose using 4D-CT was 98.9%, indicating the necessity of dose accumulation using 4D-CT. The measured doses using OSL and theoretically calculated doses using probability distribution function at the corresponding position were comparable. Conclusion: Use of static dose calculation in the treatment planning system could substantially underestimate the actually delivered dose in the MD region for a moving target. Funding Supported by NSFC, No.81372436.« less

Exposure of airport workers to radiation from shipments of radioactive materials. A review of studies conducted at six major airports. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shapiro, J.

1976-02-01

The radiation exposure of airport workers handling shipments of radioactive materials was studied at six airports. Descriptions were obtained of the handling and arrangement of the packages, dose distributions were mapped around groupings of packages, and doses received by workers were evaluated both on the basis of time-motion studies and through readings of personal monitoring devices. Results of dosimeters worn over extended periods indicated that no workers were expected to receive exposures in excess of 500 millirems per year and most were expected to receive less than 100 millirems per year. No evidence was found in any of the sixmore » airport studies to suggest that members of the public received any exposure of significance relative to the natural background radiation.« less

Dosimetric calculations for uranium miners for epidemiological studies.

PubMed

Marsh, J W; Blanchardon, E; Gregoratto, D; Hofmann, W; Karcher, K; Nosske, D; Tomásek, L

2012-05-01

Epidemiological studies on uranium miners are being carried out to quantify the risk of cancer based on organ dose calculations. Mathematical models have been applied to calculate the annual absorbed doses to regions of the lung, red bone marrow, liver, kidney and stomach for each individual miner arising from exposure to radon gas, radon progeny and long-lived radionuclides (LLR) present in the uranium ore dust and to external gamma radiation. The methodology and dosimetric models used to calculate these organ doses are described and the resulting doses for unit exposure to each source (radon gas, radon progeny and LLR) are presented. The results of dosimetric calculations for a typical German miner are also given. For this miner, the absorbed dose to the central regions of the lung is dominated by the dose arising from exposure to radon progeny, whereas the absorbed dose to the red bone marrow is dominated by the external gamma dose. The uncertainties in the absorbed dose to regions of the lung arising from unit exposure to radon progeny are also discussed. These dose estimates are being used in epidemiological studies of cancer in uranium miners.

Online 3D EPID-based dose verification: Proof of concept.

PubMed

Spreeuw, Hanno; Rozendaal, Roel; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben; van Herk, Marcel

2016-07-01

Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame, including dose verification, took 266 ± 11 ms on a dual octocore Intel Xeon E5-2630 CPU running at 2.40 GHz. The introduced delivery errors were detected after 5-10 s irradiation time. A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for two different kinds of gross delivery errors. Thus, online 3D dose verification has been technologically achieved.

An Investigation of Nonuniform Dose Deposition From an Electron Beam

DTIC Science & Technology

1994-08-01

to electron - beam pulse. Ceramic package HIPEC Lid Electron beam Die Bond wires TLD TLD Silver epoxy 6 package cavity die TLD’s 21 3 4 5 Figure 2...these apertures was documented in a previous experiment relating to HIFX electron -beam dosimetry .2 The hardware required for this setup was a 60-cm...impurity serves 2Gregory K. Ovrebo, Steven M. Blomquist, and Steven R. Murrill, A HIFX Electron -Beam Dosimetry System, Army Research Laboratory, ARL-TR

Isobio software: biological dose distribution and biological dose volume histogram from physical dose conversion using linear-quadratic-linear model.

PubMed

Jaikuna, Tanwiwat; Khadsiri, Phatchareewan; Chawapun, Nisa; Saekho, Suwit; Tharavichitkul, Ekkasit

2017-02-01

To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL) model. The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR), and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system. An equivalent dose in 2 Gy fraction (EQD 2 ) was calculated using biological effective dose (BED) based on the LQL model. The software calculation and the manual calculation were compared for EQD 2 verification with pair t -test statistical analysis using IBM SPSS Statistics version 22 (64-bit). Two and three-dimensional biological dose distribution and biological dose volume histogram were displayed correctly by the Isobio software. Different physical doses were found between CERR and treatment planning system (TPS) in Oncentra, with 3.33% in high-risk clinical target volume (HR-CTV) determined by D 90% , 0.56% in the bladder, 1.74% in the rectum when determined by D 2cc , and less than 1% in Pinnacle. The difference in the EQD 2 between the software calculation and the manual calculation was not significantly different with 0.00% at p -values 0.820, 0.095, and 0.593 for external beam radiation therapy (EBRT) and 0.240, 0.320, and 0.849 for brachytherapy (BT) in HR-CTV, bladder, and rectum, respectively. The Isobio software is a feasible tool to generate the biological dose distribution and biological dose volume histogram for treatment plan evaluation in both EBRT and BT.

Clinical implementation and evaluation of the Acuros dose calculation algorithm.

PubMed

Yan, Chenyu; Combine, Anthony G; Bednarz, Greg; Lalonde, Ronald J; Hu, Bin; Dickens, Kathy; Wynn, Raymond; Pavord, Daniel C; Saiful Huq, M

2017-09-01

The main aim of this study is to validate the Acuros XB dose calculation algorithm for a Varian Clinac iX linac in our clinics, and subsequently compare it with the wildely used AAA algorithm. The source models for both Acuros XB and AAA were configured by importing the same measured beam data into Eclipse treatment planning system. Both algorithms were validated by comparing calculated dose with measured dose on a homogeneous water phantom for field sizes ranging from 6 cm × 6 cm to 40 cm × 40 cm. Central axis and off-axis points with different depths were chosen for the comparison. In addition, the accuracy of Acuros was evaluated for wedge fields with wedge angles from 15 to 60°. Similarly, variable field sizes for an inhomogeneous phantom were chosen to validate the Acuros algorithm. In addition, doses calculated by Acuros and AAA at the center of lung equivalent tissue from three different VMAT plans were compared to the ion chamber measured doses in QUASAR phantom, and the calculated dose distributions by the two algorithms and their differences on patients were compared. Computation time on VMAT plans was also evaluated for Acuros and AAA. Differences between dose-to-water (calculated by AAA and Acuros XB) and dose-to-medium (calculated by Acuros XB) on patient plans were compared and evaluated. For open 6 MV photon beams on the homogeneous water phantom, both Acuros XB and AAA calculations were within 1% of measurements. For 23 MV photon beams, the calculated doses were within 1.5% of measured doses for Acuros XB and 2% for AAA. Testing on the inhomogeneous phantom demonstrated that AAA overestimated doses by up to 8.96% at a point close to lung/solid water interface, while Acuros XB reduced that to 1.64%. The test on QUASAR phantom showed that Acuros achieved better agreement in lung equivalent tissue while AAA underestimated dose for all VMAT plans by up to 2.7%. Acuros XB computation time was about three times faster than AAA for VMAT plans, and computation time for other plans will be discussed at the end. Maximum difference between dose calculated by AAA and dose-to-medium by Acuros XB (Acuros_D m,m ) was 4.3% on patient plans at the isocenter, and maximum difference between D 100 calculated by AAA and by Acuros_D m,m was 11.3%. When calculating the maximum dose to spinal cord on patient plans, differences between dose calculated by AAA and Acuros_D m,m were more than 3%. Compared with AAA, Acuros XB improves accuracy in the presence of inhomogeneity, and also significantly reduces computation time for VMAT plans. Dose differences between AAA and Acuros_D w,m were generally less than the dose differences between AAA and Acuros_D m,m . Clinical practitioners should consider making Acuros XB available in clinics, however, further investigation and clarification is needed about which dose reporting mode (dose-to-water or dose-to-medium) should be used in clinics. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

TH-A-19A-06: Site-Specific Comparison of Analytical and Monte Carlo Based Dose Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuemann, J; Grassberger, C; Paganetti, H

2014-06-15

Purpose: To investigate the impact of complex patient geometries on the capability of analytical dose calculation algorithms to accurately predict dose distributions and to verify currently used uncertainty margins in proton therapy. Methods: Dose distributions predicted by an analytical pencilbeam algorithm were compared with Monte Carlo simulations (MCS) using TOPAS. 79 complete patient treatment plans were investigated for 7 disease sites (liver, prostate, breast, medulloblastoma spine and whole brain, lung and head and neck). A total of 508 individual passively scattered treatment fields were analyzed for field specific properties. Comparisons based on target coverage indices (EUD, D95, D90 and D50)more » were performed. Range differences were estimated for the distal position of the 90% dose level (R90) and the 50% dose level (R50). Two-dimensional distal dose surfaces were calculated and the root mean square differences (RMSD), average range difference (ARD) and average distal dose degradation (ADD), the distance between the distal position of the 80% and 20% dose levels (R80- R20), were analyzed. Results: We found target coverage indices calculated by TOPAS to generally be around 1–2% lower than predicted by the analytical algorithm. Differences in R90 predicted by TOPAS and the planning system can be larger than currently applied range margins in proton therapy for small regions distal to the target volume. We estimate new site-specific range margins (R90) for analytical dose calculations considering total range uncertainties and uncertainties from dose calculation alone based on the RMSD. Our results demonstrate that a reduction of currently used uncertainty margins is feasible for liver, prostate and whole brain fields even without introducing MC dose calculations. Conclusion: Analytical dose calculation algorithms predict dose distributions within clinical limits for more homogeneous patients sites (liver, prostate, whole brain). However, we recommend treatment plan verification using Monte Carlo simulations for patients with complex geometries.« less

SU-F-T-157: Physics Considerations Regarding Dosimetric Accuracy of Analytical Dose Calculations for Small Field Proton Therapy: A Monte Carlo Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, C; Nanjing University of Aeronautics and Astronautics, Nanjing; Daartz, J

Purpose: To evaluate the accuracy of dose calculations by analytical dose calculation methods (ADC) for small field proton therapy in a gantry based passive scattering facility. Methods: 50 patients with intra-cranial disease were evaluated in the study. Treatment plans followed standard prescription and optimization procedures of proton stereotactic radiosurgery. Dose distributions calculated with the Monte Carlo (MC) toolkit TOPAS were used to represent delivered treatments. The MC dose was first adjusted using the output factor (OF) applied clinically. This factor is determined from the field size and the prescribed range. We then introduced a normalization factor to measure the differencemore » in mean dose between the delivered dose (MC dose with OF) and the dose calculated by ADC for each beam. The normalization was determined by the mean dose of the center voxels of the target area. We compared delivered dose distributions and those calculated by ADC in terms of dose volume histogram parameters and beam range distributions. Results: The mean target dose for a whole treatment is generally within 5% comparing delivered dose (MC dose with OF) and ADC dose. However, the differences can be as great as 11% for shallow and small target treated with a thick range compensator. Applying the normalization factor to the MC dose with OF can reduce the mean dose difference to less than 3%. Considering range uncertainties, the generally applied margins (3.5% of the prescribed range + 1mm) to cover uncertainties in range might not be sufficient to guarantee tumor coverage. The range difference for R90 (90% distal dose falloff) is affected by multiple factors, such as the heterogeneity index. Conclusion: This study indicates insufficient accuracy calculating proton doses using ADC. Our results suggest that uncertainties of target doses are reduced using MC techniques, improving the dosimetric accuracy for proton stereotactic radiosurgery. The work was supported by NIH/NCI under CA U19 021239. CG was partially supported by the Chinese Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant No. 11475087).« less

batman: BAsic Transit Model cAlculatioN in Python

NASA Astrophysics Data System (ADS)

Kreidberg, Laura

2015-10-01

batman provides fast calculation of exoplanet transit light curves and supports calculation of light curves for any radially symmetric stellar limb darkening law. It uses an integration algorithm for models that cannot be quickly calculated analytically, and in typical use, the batman Python package can calculate a million model light curves in well under ten minutes for any limb darkening profile.

SU-E-T-02: 90Y Microspheres Dosimetry Calculation with Voxel-S-Value Method: A Simple Use in the Clinic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maneru, F; Gracia, M; Gallardo, N

2015-06-15

Purpose: To present a simple and feasible method of voxel-S-value (VSV) dosimetry calculation for daily clinical use in radioembolization (RE) with {sup 90}Y microspheres. Dose distributions are obtained and visualized over CT images. Methods: Spatial dose distributions and dose in liver and tumor are calculated for RE patients treated with Sirtex Medical miscrospheres at our center. Data obtained from the previous simulation of treatment were the basis for calculations: Tc-99m maggregated albumin SPECT-CT study in a gammacamera (Infinia, General Electric Healthcare.). Attenuation correction and ordered-subsets expectation maximization (OSEM) algorithm were applied.For VSV calculations, both SPECT and CT were exported frommore » the gammacamera workstation and registered with the radiotherapy treatment planning system (Eclipse, Varian Medical systems). Convolution of activity matrix and local dose deposition kernel (S values) was implemented with an in-house developed software based on Python code. The kernel was downloaded from www.medphys.it. Final dose distribution was evaluated with the free software Dicompyler. Results: Liver mean dose is consistent with Partition method calculations (accepted as a good standard). Tumor dose has not been evaluated due to the high dependence on its contouring. Small lesion size, hot spots in health tissue and blurred limits can affect a lot the dose distribution in tumors. Extra work includes: export and import of images and other dicom files, create and calculate a dummy plan of external radiotherapy, convolution calculation and evaluation of the dose distribution with dicompyler. Total time spent is less than 2 hours. Conclusion: VSV calculations do not require any extra appointment or any uncomfortable process for patient. The total process is short enough to carry it out the same day of simulation and to contribute to prescription decisions prior to treatment. Three-dimensional dose knowledge provides much more information than other methods of dose calculation usually applied in the clinic.« less

Experimental validation of the DARWIN2.3 package for fuel cycle applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

San-Felice, L.; Eschbach, R.; Bourdot, P.

2012-07-01

The DARWIN package, developed by the CEA and its French partners (AREVA and EDF) provides the required parameters for fuel cycle applications: fuel inventory, decay heat, activity, neutron, {gamma}, {alpha}, {beta} sources and spectrum, radiotoxicity. This paper presents the DARWIN2.3 experimental validation for fuel inventory and decay heat calculations on Pressurized Water Reactor (PWR). In order to validate this code system for spent fuel inventory a large program has been undertaken, based on spent fuel chemical assays. This paper deals with the experimental validation of DARWIN2.3 for the Pressurized Water Reactor (PWR) Uranium Oxide (UOX) and Mixed Oxide (MOX) fuelmore » inventory calculation, focused on the isotopes involved in Burn-Up Credit (BUC) applications and decay heat computations. The calculation - experiment (C/E-1) discrepancies are calculated with the latest European evaluation file JEFF-3.1.1 associated with the SHEM energy mesh. An overview of the tendencies is obtained on a complete range of burn-up from 10 to 85 GWd/t (10 to 60 GWcVt for MOX fuel). The experimental validation of the DARWIN2.3 package for decay heat calculation is performed using calorimetric measurements carried out at the Swedish Interim Spent Fuel Storage Facility for Pressurized Water Reactor (PWR) assemblies, covering a large burn-up (20 to 50 GWd/t) and cooling time range (10 to 30 years). (authors)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klüter, Sebastian, E-mail: sebastian.klueter@med.uni-heidelberg.de; Schubert, Kai; Lissner, Steffen

Purpose: The dosimetric verification of treatment plans in helical tomotherapy usually is carried out via verification measurements. In this study, a method for independent dose calculation of tomotherapy treatment plans is presented, that uses a conventional treatment planning system with a pencil kernel dose calculation algorithm for generation of verification dose distributions based on patient CT data. Methods: A pencil beam algorithm that directly uses measured beam data was configured for dose calculation for a tomotherapy machine. Tomotherapy treatment plans were converted into a format readable by an in-house treatment planning system by assigning each projection to one static treatmentmore » field and shifting the calculation isocenter for each field in order to account for the couch movement. The modulation of the fluence for each projection is read out of the delivery sinogram, and with the kernel-based dose calculation, this information can directly be used for dose calculation without the need for decomposition of the sinogram. The sinogram values are only corrected for leaf output and leaf latency. Using the converted treatment plans, dose was recalculated with the independent treatment planning system. Multiple treatment plans ranging from simple static fields to real patient treatment plans were calculated using the new approach and either compared to actual measurements or the 3D dose distribution calculated by the tomotherapy treatment planning system. In addition, dose–volume histograms were calculated for the patient plans. Results: Except for minor deviations at the maximum field size, the pencil beam dose calculation for static beams agreed with measurements in a water tank within 2%/2 mm. A mean deviation to point dose measurements in the cheese phantom of 0.89% ± 0.81% was found for unmodulated helical plans. A mean voxel-based deviation of −0.67% ± 1.11% for all voxels in the respective high dose region (dose values >80%), and a mean local voxel-based deviation of −2.41% ± 0.75% for all voxels with dose values >20% were found for 11 modulated plans in the cheese phantom. Averaged over nine patient plans, the deviations amounted to −0.14% ± 1.97% (voxels >80%) and −0.95% ± 2.27% (>20%, local deviations). For a lung case, mean voxel-based deviations of more than 4% were found, while for all other patient plans, all mean voxel-based deviations were within ±2.4%. Conclusions: The presented method is suitable for independent dose calculation for helical tomotherapy within the known limitations of the pencil beam algorithm. It can serve as verification of the primary dose calculation and thereby reduce the need for time-consuming measurements. By using the patient anatomy and generating full 3D dose data, and combined with measurements of additional machine parameters, it can substantially contribute to overall patient safety.« less

40 CFR 63.825 - Standards: Product and packaging rotogravure and wide-web flexographic printing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... within ±2.0 percent. (vi) Measure the amount of volatile matter recovered for the month. (vii) Calculate... rotogravure and wide-web flexographic printing. 63.825 Section 63.825 Protection of Environment ENVIRONMENTAL... Industry § 63.825 Standards: Product and packaging rotogravure and wide-web flexographic printing. (a) Each...

40 CFR 63.825 - Standards: Product and packaging rotogravure and wide-web flexographic printing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... within ±2.0 percent. (vi) Measure the amount of volatile matter recovered for the month. (vii) Calculate... rotogravure and wide-web flexographic printing. 63.825 Section 63.825 Protection of Environment ENVIRONMENTAL... Industry § 63.825 Standards: Product and packaging rotogravure and wide-web flexographic printing. (a) Each...

49 CFR 173.412 - Additional design requirements for Type A packages.

Code of Federal Regulations, 2012 CFR

2012-10-01

... relief device, is provided with an enclosure to retain any leakage. (h) Any radiation shield that... structural part of the packaging, under both normal and accident conditions, must not impair the ability of... significant increase in the radiation levels recorded or calculated at the external surfaces for the condition...

49 CFR 173.412 - Additional design requirements for Type A packages.

Code of Federal Regulations, 2013 CFR

2013-10-01

... relief device, is provided with an enclosure to retain any leakage. (h) Any radiation shield that... structural part of the packaging, under both normal and accident conditions, must not impair the ability of... significant increase in the radiation levels recorded or calculated at the external surfaces for the condition...

49 CFR 173.412 - Additional design requirements for Type A packages.

Code of Federal Regulations, 2014 CFR

2014-10-01

... pressure relief device, is provided with an enclosure to retain any leakage. (h) Any radiation shield that... structural part of the packaging, under both normal and accident conditions, must not impair the ability of... significant increase in the radiation levels recorded or calculated at the external surfaces for the condition...

49 CFR 173.412 - Additional design requirements for Type A packages.

Code of Federal Regulations, 2011 CFR

2011-10-01

... relief device, is provided with an enclosure to retain any leakage. (h) Any radiation shield that... structural part of the packaging, under both normal and accident conditions, must not impair the ability of... significant increase in the radiation levels recorded or calculated at the external surfaces for the condition...

A three-dimensional potential-flow program with a geometry package for input data generation

NASA Technical Reports Server (NTRS)

Halsey, N. D.

1978-01-01

Information needed to run a computer program for the calculation of the potential flow about arbitrary three dimensional lifting configurations is presented. The program contains a geometry package which greatly reduces the task of preparing the input data. Starting from a very sparse set of coordinate data, the program automatically augments and redistributes the coordinates, calculates curves of intersection between components, and redistributes coordinates in the regions adjacent to the intersection curves in a suitable manner for use in the potential flow calculations. A brief summary of the program capabilities and options is given, as well as detailed instructions for the data input, a suggested structure for the program overlay, and the output for two test cases.

Gamma radiation effects in packaging for sterilization of health products and their constituents paper and plastic film

NASA Astrophysics Data System (ADS)

B. G. Porto, Karina Meschini; Napolitano, Celia Marina; Borrely, Sueli Ivone

2018-01-01

The integrity of materials containing packaging (natural or synthetic polymers) is essential to keep the aseptic condition of commercialized products (health care products, food and pharmaceuticals). The objective of this paper was to study gamma radiation effects (25 kGy, 40 kGy and 50 kGy) on the main properties of paper and multilayer films (polyester and polyethylene). Paper and multilayer films are components of packaging (pouches) for radiation sterilization containing medical equipment or products. Paper was the more radiation sensitive among the studied materials and radiation effects were more pronounced at brightness, pH, tearing resistance, bursting strength and tensile strength. Concerning plastic film, no pinholes were induced by radiation and the effects on the tensile strength were not significant. Although the seal strength packaging (pouches) decreased according to increasing dose, the sealing integrity was preserved.

Study of multilayer polymer materials after ionization treatment

NASA Astrophysics Data System (ADS)

Tarasyuk, V. T.; Semkina, A. A.; Solovyeva, V. I.; Fedotova, D. D.; Strokova, N. E.; Malenko, D. M.; Baranov, O. V.; Bakumenko, A. V.; Puchkov, S. N.; Prokopenko, A. V.

2017-12-01

Electron-beam technologies of food products processing involves the use of modern packaging materials in form of polymer films of different composition. The objective of the research is to study the impact of accelerated electrons on the structure of the polymeric packaging materials used for storage of agricultural products. It was investigated radiation exposure on film material PE/PA (80/20) with a thickness of 80 mkm. This film used for storage of vegetables and fruits and has the necessary indicators for gas and vapor permeability. Electron beam treatment of the films was performed on a compact radiation sterilization installation with local bio-protection with electron energy of 5 MeV. A polymer films were irradiated with doses from 1 to 10 kGy. Changing the structure of the film composition was monitored by IR spectrometry. As a result of irradiation by accelerated electrons with doses up to 18 kGy is established that the polymer film is modification of the polymeric material in the form of a partial degradation with subsequent intra-molecular crosslinking. This improves the physico-mechanical properties in the transverse direction, and such film can be used for food packaging before electron-beam treatment.

Implementation and use of direct-flow connections in a coupled ground-water and surface-water model

USGS Publications Warehouse

Swain, Eric D.

1994-01-01

The U.S. Geological Survey's MODFLOW finite-difference ground-water flow model has been coupled with three surface-water packages - the MODBRANCH, River, and Stream packages - to simulate surface water and its interaction with ground water. Prior to the development of the coupling packages, the only interaction between these modeling packages was that leakage values could be passed between MODFLOW and the three surface-water packages. To facilitate wider and more flexible uses of the models, a computer program was developed and added to MODFLOW to allow direct flows or stages to be passed between any of the packages and MODFLOW. The flows or stages calculated in one package can be set as boundary discharges or stages to be used in another package. Several modeling packages can be used in the same simulation depending upon the level of sophistication needed in the various reaches being modeled. This computer program is especially useful when any of the River, Stream, or MODBRANCH packages are used to model a river flowing directly into or out of wetlands in direct connection with the aquifer and represented in the model as an aquifer block. A field case study is shown to illustrate an application.

Verification of calculated skin doses in postmastectomy helical tomotherapy.

PubMed

Ito, Shima; Parker, Brent C; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth

2011-10-01

To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi·Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. The mean difference and standard error of the mean difference between measurement and calculation for the scar measurements was -1.8% ± 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% ± 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% ± 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%. Copyright © 2011 Elsevier Inc. All rights reserved.

Verification of Calculated Skin Doses in Postmastectomy Helical Tomotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, Shima; Parker, Brent C., E-mail: bcparker@marybird.com; Mary Bird Perkins Cancer Center, Baton Rouge, LA

2011-10-01

Purpose: To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). Methods and Materials: In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi.Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. Results: The mean difference and standard errormore » of the mean difference between measurement and calculation for the scar measurements was -1.8% {+-} 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% {+-} 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% {+-} 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. Conclusions: The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%.« less

Absorbed dose measurement in low temperature samples:. comparative methods using simulated material

NASA Astrophysics Data System (ADS)

Garcia, Ruth; Harris, Anthony; Winters, Martell; Howard, Betty; Mellor, Paul; Patil, Deepak; Meiner, Jason

2004-09-01

There is a growing need to reliably measure absorbed dose in low temperature samples, especially in the pharmaceutical and tissue banking industries. All dosimetry systems commonly used in the irradiation industry are temperature sensitive. Radiation of low temperature samples, such as those packaged with dry ice, must therefore take these dosimeter temperature effects into consideration. This paper will suggest a method to accurately deliver an absorbed radiation dose using dosimetry techniques designed to abrogate the skewing effects of low temperature environments on existing dosimetry systems.

The development and validation of a Monte Carlo model for calculating the out-of-field dose from radiotherapy treatments

NASA Astrophysics Data System (ADS)

Kry, Stephen

Introduction. External beam photon radiotherapy is a common treatment for many malignancies, but results in the exposure of the patient to radiation away from the treatment site. This out-of-field radiation irradiates healthy tissue and may lead to the induction of secondary malignancies. Out-of-field radiation is composed of photons and, at high treatment energies, neutrons. Measurement of this out-of-field dose is time consuming, often difficult, and is specific to the conditions of the measurements. Monte Carlo simulations may be a viable approach to determining the out-of-field dose quickly, accurately, and for arbitrary irradiation conditions. Methods. An accelerator head, gantry, and treatment vault were modeled with MCNPX and 6 MV and 18 MV beams were simulated. Photon doses were calculated in-field and compared to measurements made with an ion chamber in a water tank. Photon doses were also calculated out-of-field from static fields and compared to measurements made with thermoluminescent dosimeters in acrylic. Neutron fluences were calculated and compared to measurements made with gold foils. Finally, photon and neutron dose equivalents were calculated in an anthropomorphic phantom following intensity-modulated radiation therapy and compared to previously published dose equivalents. Results. The Monte Carlo model was able to accurately calculate the in-field dose. From static treatment fields, the model was also able to calculate the out-of-field photon dose within 16% at 6 MV and 17% at 18 MV and the neutron fluence within 19% on average. From the simulated IMRT treatments, the calculated out-of-field photon dose was within 14% of measurement at 6 MV and 13% at 18 MV on average. The calculated neutron dose equivalent was much lower than the measured value but is likely accurate because the measured neutron dose equivalent was based on an overestimated neutron energy. Based on the calculated out-of-field doses generated by the Monte Carlo model, it was possible to estimate the risk of fatal secondary malignancy, which was consistent with previous estimates except for the neutron discrepancy. Conclusions. The Monte Carlo model developed here is well suited to studying the out-of-field dose equivalent from photons and neutrons under a variety of irradiation configurations, including complex treatments on complex phantoms. Based on the calculated dose equivalents, it is possible to estimate the risk of secondary malignancy associated with out-of-field doses. The Monte Carlo model should be used to study, quantify, and minimize the out-of-field dose equivalent and associated risks received by patients undergoing radiation therapy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Z; Baker, J; Hsia, A

Purpose: The commercially available Leipzig-style Cone for High Dose Rate (HDR) Brachytherapy has a steep depth dose curve and a non-uniform dose distribution. This work shows the performance of a Ring Surface Applicator created using a 3D printer that can generate a better dose distribution. Calculated doses were verified with film measurement. Methods: The water equivalent red-ABS plastic was used to print the Ring Surface Applicator which hosts three catheters: a center piece with a straight catheter and two concentric rings with diameters of 3.5 and 5.5 cm. Gafchromic EBT2 film, Epson Expression 10000 flatbed scanner, and the online softwaremore » at radiochromic.com were used to analyze the measured data. 10cm×10cm piece of film was sandwiched between two 15×10×5cm3 polystyrene phantoms. The applicator was positioned directly on top of the phantom. Measurement was done using dwell time and positions calculated by Eclipse BrachyVision treatment planning system (RTP). Results: Depth dose curve was generated from the plan and measurement. The results show that the measured and calculated depth dose were in agreement (<3%) from surface to 4mm depth. A discrepancy of 6% was observed at 5 mm depth, where the dose is typically prescribed to. For depths deeper than 5 mm, the measured doses were lower than those calculated by Eclipse BrachyVision. This can be attributed to a combination of simple calculation algorithm using TG-43 and the lack of inhomogeneity correction. Dose profiles at 5 mm depth were also generated from TPS calculation and measured with film. The measured and calculated profiles are similar. Consistent with the depth dose curve, the measured dose is lower than the calculated. Conclusion: Our results showed that the Ring Surface Applicator, printed using 3D printer, can generate more uniform dose distribution within the target volume and can be safely used in the clinic.« less

MSTor version 2013: A new version of the computer code for the multi-structural torsional anharmonicity, now with a coupled torsional potential

NASA Astrophysics Data System (ADS)

Zheng, Jingjing; Meana-Pañeda, Rubén; Truhlar, Donald G.

2013-08-01

We present an improved version of the MSTor program package, which calculates partition functions and thermodynamic functions of complex molecules involving multiple torsions; the method is based on either a coupled torsional potential or an uncoupled torsional potential. The program can also carry out calculations in the multiple-structure local harmonic approximation. The program package also includes seven utility codes that can be used as stand-alone programs to calculate reduced moment of inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes for torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files for the MSTor calculation and Voronoi calculation, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method. Restrictions: There is no limit on the number of torsions that can be included in either the Voronoi calculation or the full MS-T calculation. In practice, the range of problems that can be addressed with the present method consists of all multitorsional problems for which one can afford to calculate all the conformational structures and their frequencies. Unusual features: The method can be applied to transition states as well as stable molecules. The program package also includes the hull program for the calculation of Voronoi volumes, the symmetry program for determining point group symmetry of a molecule, and seven utility codes that can be used as stand-alone programs to calculate reduced moment-of-inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes of the torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method. Additional comments: The program package includes a manual, installation script, and input and output files for a test suite. Running time: There are 26 test runs. The running time of the test runs on a single processor of the Itasca computer is less than 2 s. References: [1] MS-T(C) method: Quantum Thermochemistry: Multi-Structural Method with Torsional Anharmonicity Based on a Coupled Torsional Potential, J. Zheng and D.G. Truhlar, Journal of Chemical Theory and Computation 9 (2013) 1356-1367, DOI: http://dx.doi.org/10.1021/ct3010722. [2] MS-T(U) method: Practical Methods for Including Torsional Anharmonicity in Thermochemical Calculations of Complex Molecules: The Internal-Coordinate Multi-Structural Approximation, J. Zheng, T. Yu, E. Papajak, I, M. Alecu, S.L. Mielke, and D.G. Truhlar, Physical Chemistry Chemical Physics 13 (2011) 10885-10907.

Targeted Nanoparticle Tested in Patients with Cancer

Cancer.gov

By packaging molecules of the chemotherapy drug docetaxel in nanoparticles, researchers aim to deliver a high dose directly to tumors and reduce the drug's toxicity. A trial to test the targeted nanoparticle is underway in humans.

Dose calculation accuracy of the Monte Carlo algorithm for CyberKnife compared with other commercially available dose calculation algorithms.

PubMed

Sharma, Subhash; Ott, Joseph; Williams, Jamone; Dickow, Danny

2011-01-01

Monte Carlo dose calculation algorithms have the potential for greater accuracy than traditional model-based algorithms. This enhanced accuracy is particularly evident in regions of lateral scatter disequilibrium, which can develop during treatments incorporating small field sizes and low-density tissue. A heterogeneous slab phantom was used to evaluate the accuracy of several commercially available dose calculation algorithms, including Monte Carlo dose calculation for CyberKnife, Analytical Anisotropic Algorithm and Pencil Beam convolution for the Eclipse planning system, and convolution-superposition for the Xio planning system. The phantom accommodated slabs of varying density; comparisons between planned and measured dose distributions were accomplished with radiochromic film. The Monte Carlo algorithm provided the most accurate comparison between planned and measured dose distributions. In each phantom irradiation, the Monte Carlo predictions resulted in gamma analysis comparisons >97%, using acceptance criteria of 3% dose and 3-mm distance to agreement. In general, the gamma analysis comparisons for the other algorithms were <95%. The Monte Carlo dose calculation algorithm for CyberKnife provides more accurate dose distribution calculations in regions of lateral electron disequilibrium than commercially available model-based algorithms. This is primarily because of the ability of Monte Carlo algorithms to implicitly account for tissue heterogeneities, density scaling functions; and/or effective depth correction factors are not required. Copyright © 2011 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Testing a structural model for viral DNA packaging motor function by optical tweezers measurements, site directed mutagenesis, and molecular dynamics calculations

NASA Astrophysics Data System (ADS)

Keller, Nicholas A.; Migliori, Amy D.; Arya, Gaurav; Rao, Venigalla B.; Smith, Douglas E.

2013-09-01

Many double-stranded DNA viruses employ a molecular motor to package DNA into preformed capsid shells. Based on structures of phage T4 motor proteins determined by X-ray crystallography and cryo-electron microscopy, Rao, Rossmann and coworkers recently proposed a structural model for motor function. They proposed that DNA is ratcheted by a large conformational change driven by electrostatic interactions between charged residues at an interface between two globular domains of the motor protein. We have conducted experiments to test this model by studying the effect on packaging under applied load of site-directed changes altering these residues. We observe significant impairment of packaging activity including reductions in packaging rate, percent time packaging, and time active under high load. We show that these measured impairments correlate well with alterations in free energies associated with the conformational change predicted by molecular dynamics simulations.

[Status and trend for sodium content of Chinese per-packaged foods].

PubMed

Zhang, Xuesong; Wang, Zhu; He, Mei; Men, Jianhua; Yang, Jingming; Shen, Xiang; Lu, Ying; Yang, Yuexin

2014-03-01

To collect the data on the sodium content of Chinese per-packaged foods, and to analyze the variation trend of sodium content. 1279 data on the sodium content of per-packaged foods in all were recorded and analyzed through the investigation of per-packaged food nutrition labels, and were categorized into 31 varieties. Median sodium content and variation were calculated for each variety and compared with 2004 sodium content data on China Food Composition. There are 6 per-packaged foods varieties has the median sodium content more than 500 mg/100 g. The food varieties with the highest mean sodium content were ready-to-eat food(2500 mg/100 g), followed by instant noodles (1900 mg/100 g). Compared with 1991 -2004 per-packaged foods sodium content, 13 varieties had medium sodium content that increased, and 5 varieties increased significantly, such as cake, liquid milk, instant noodles etc. The survey show that sodium content of some per-packaged food increased.

modlAMP: Python for antimicrobial peptides.

PubMed

Müller, Alex T; Gabernet, Gisela; Hiss, Jan A; Schneider, Gisbert

2017-09-01

We have implemented the lecular esign aboratory's nti icrobial eptides package ( ), a Python-based software package for the design, classification and visual representation of peptide data. modlAMP offers functions for molecular descriptor calculation and the retrieval of amino acid sequences from public or local sequence databases, and provides instant access to precompiled datasets for machine learning. The package also contains methods for the analysis and representation of circular dichroism spectra. The modlAMP Python package is available under the BSD license from URL http://doi.org/10.5905/ethz-1007-72 or via pip from the Python Package Index (PyPI). gisbert.schneider@pharma.ethz.ch. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Simulation-based Bayesian inference for latent traits of item response models: Introduction to the ltbayes package for R.

PubMed

Johnson, Timothy R; Kuhn, Kristine M

2015-12-01

This paper introduces the ltbayes package for R. This package includes a suite of functions for investigating the posterior distribution of latent traits of item response models. These include functions for simulating realizations from the posterior distribution, profiling the posterior density or likelihood function, calculation of posterior modes or means, Fisher information functions and observed information, and profile likelihood confidence intervals. Inferences can be based on individual response patterns or sets of response patterns such as sum scores. Functions are included for several common binary and polytomous item response models, but the package can also be used with user-specified models. This paper introduces some background and motivation for the package, and includes several detailed examples of its use.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y; Liu, B; Liang, B

Purpose: Current CyberKnife treatment planning system (TPS) provided two dose calculation algorithms: Ray-tracing and Monte Carlo. Ray-tracing algorithm is fast, but less accurate, and also can’t handle irregular fields since a multi-leaf collimator system was recently introduced to CyberKnife M6 system. Monte Carlo method has well-known accuracy, but the current version still takes a long time to finish dose calculations. The purpose of this paper is to develop a GPU-based fast C/S dose engine for CyberKnife system to achieve both accuracy and efficiency. Methods: The TERMA distribution from a poly-energetic source was calculated based on beam’s eye view coordinate system,more » which is GPU friendly and has linear complexity. The dose distribution was then computed by inversely collecting the energy depositions from all TERMA points along 192 collapsed-cone directions. EGSnrc user code was used to pre-calculate energy deposition kernels (EDKs) for a series of mono-energy photons The energy spectrum was reconstructed based on measured tissue maximum ratio (TMR) curve, the TERMA averaged cumulative kernels was then calculated. Beam hardening parameters and intensity profiles were optimized based on measurement data from CyberKnife system. Results: The difference between measured and calculated TMR are less than 1% for all collimators except in the build-up regions. The calculated profiles also showed good agreements with the measured doses within 1% except in the penumbra regions. The developed C/S dose engine was also used to evaluate four clinical CyberKnife treatment plans, the results showed a better dose calculation accuracy than Ray-tracing algorithm compared with Monte Carlo method for heterogeneous cases. For the dose calculation time, it takes about several seconds for one beam depends on collimator size and dose calculation grids. Conclusion: A GPU-based C/S dose engine has been developed for CyberKnife system, which was proven to be efficient and accurate for clinical purpose, and can be easily implemented in TPS.« less

Sub-second pencil beam dose calculation on GPU for adaptive proton therapy.

PubMed

da Silva, Joakim; Ansorge, Richard; Jena, Rajesh

2015-06-21

Although proton therapy delivered using scanned pencil beams has the potential to produce better dose conformity than conventional radiotherapy, the created dose distributions are more sensitive to anatomical changes and patient motion. Therefore, the introduction of adaptive treatment techniques where the dose can be monitored as it is being delivered is highly desirable. We present a GPU-based dose calculation engine relying on the widely used pencil beam algorithm, developed for on-line dose calculation. The calculation engine was implemented from scratch, with each step of the algorithm parallelized and adapted to run efficiently on the GPU architecture. To ensure fast calculation, it employs several application-specific modifications and simplifications, and a fast scatter-based implementation of the computationally expensive kernel superposition step. The calculation time for a skull base treatment plan using two beam directions was 0.22 s on an Nvidia Tesla K40 GPU, whereas a test case of a cubic target in water from the literature took 0.14 s to calculate. The accuracy of the patient dose distributions was assessed by calculating the γ-index with respect to a gold standard Monte Carlo simulation. The passing rates were 99.2% and 96.7%, respectively, for the 3%/3 mm and 2%/2 mm criteria, matching those produced by a clinical treatment planning system.

IMRT head and neck treatment planning with a commercially available Monte Carlo based planning system

NASA Astrophysics Data System (ADS)

Boudreau, C.; Heath, E.; Seuntjens, J.; Ballivy, O.; Parker, W.

2005-03-01

The PEREGRINE Monte Carlo dose-calculation system (North American Scientific, Cranberry Township, PA) is the first commercially available Monte Carlo dose-calculation code intended specifically for intensity modulated radiotherapy (IMRT) treatment planning and quality assurance. In order to assess the impact of Monte Carlo based dose calculations for IMRT clinical cases, dose distributions for 11 head and neck patients were evaluated using both PEREGRINE and the CORVUS (North American Scientific, Cranberry Township, PA) finite size pencil beam (FSPB) algorithm with equivalent path-length (EPL) inhomogeneity correction. For the target volumes, PEREGRINE calculations predict, on average, a less than 2% difference in the calculated mean and maximum doses to the gross tumour volume (GTV) and clinical target volume (CTV). An average 16% ± 4% and 12% ± 2% reduction in the volume covered by the prescription isodose line was observed for the GTV and CTV, respectively. Overall, no significant differences were noted in the doses to the mandible and spinal cord. For the parotid glands, PEREGRINE predicted a 6% ± 1% increase in the volume of tissue receiving a dose greater than 25 Gy and an increase of 4% ± 1% in the mean dose. Similar results were noted for the brainstem where PEREGRINE predicted a 6% ± 2% increase in the mean dose. The observed differences between the PEREGRINE and CORVUS calculated dose distributions are attributed to secondary electron fluence perturbations, which are not modelled by the EPL correction, issues of organ outlining, particularly in the vicinity of air cavities, and differences in dose reporting (dose to water versus dose to tissue type).

Epp: A C++ EGSnrc user code for x-ray imaging and scattering simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lippuner, Jonas; Elbakri, Idris A.; Cui Congwu

2011-03-15

Purpose: Easy particle propagation (Epp) is a user code for the EGSnrc code package based on the C++ class library egspp. A main feature of egspp (and Epp) is the ability to use analytical objects to construct simulation geometries. The authors developed Epp to facilitate the simulation of x-ray imaging geometries, especially in the case of scatter studies. While direct use of egspp requires knowledge of C++, Epp requires no programming experience. Methods: Epp's features include calculation of dose deposited in a voxelized phantom and photon propagation to a user-defined imaging plane. Projection images of primary, single Rayleigh scattered, singlemore » Compton scattered, and multiple scattered photons may be generated. Epp input files can be nested, allowing for the construction of complex simulation geometries from more basic components. To demonstrate the imaging features of Epp, the authors simulate 38 keV x rays from a point source propagating through a water cylinder 12 cm in diameter, using both analytical and voxelized representations of the cylinder. The simulation generates projection images of primary and scattered photons at a user-defined imaging plane. The authors also simulate dose scoring in the voxelized version of the phantom in both Epp and DOSXYZnrc and examine the accuracy of Epp using the Kawrakow-Fippel test. Results: The results of the imaging simulations with Epp using voxelized and analytical descriptions of the water cylinder agree within 1%. The results of the Kawrakow-Fippel test suggest good agreement between Epp and DOSXYZnrc. Conclusions: Epp provides the user with useful features, including the ability to build complex geometries from simpler ones and the ability to generate images of scattered and primary photons. There is no inherent computational time saving arising from Epp, except for those arising from egspp's ability to use analytical representations of simulation geometries. Epp agrees with DOSXYZnrc in dose calculation, since they are both based on the well-validated standard EGSnrc radiation transport physics model.« less

Practical applications of internal dose calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carbaugh, E.H.

1994-06-01

Accurate estimates of intake magnitude and internal dose are the goal for any assessment of an actual intake of radioactivity. When only one datum is available on which to base estimates, the choices for internal dose assessment become straight-forward: apply the appropriate retention or excretion function, calculate the intake, and calculate the dose. The difficulty comes when multiple data and different types of data become available. Then practical decisions must be made on how to interpret conflicting data, or how to adjust the assumptions and techniques underlying internal dose assessments to give results consistent with the data. This article describesmore » nine types of adjustments which can be incorporated into calculations of intake and internal dose, and then offers several practical insights to dealing with some real-world internal dose puzzles.« less

Software Package Completed for Alloy Design at the Atomic Level

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo H.; Noebe, Ronald D.; Abel, Phillip B.; Good, Brian S.

2001-01-01

As a result of a multidisciplinary effort involving solid-state physics, quantum mechanics, and materials and surface science, the first version of a software package dedicated to the atomistic analysis of multicomponent systems was recently completed. Based on the BFS (Bozzolo, Ferrante, and Smith) method for the calculation of alloy and surface energetics, this package includes modules devoted to the analysis of many essential features that characterize any given alloy or surface system, including (1) surface structure analysis, (2) surface segregation, (3) surface alloying, (4) bulk crystalline material properties and atomic defect structures, and (5) thermal processes that allow us to perform phase diagram calculations. All the modules of this Alloy Design Workbench 1.0 (ADW 1.0) are designed to run in PC and workstation environments, and their operation and performance are substantially linked to the needs of the user and the specific application.

New solution decomposition and minimization schemes for Poisson-Boltzmann equation in calculation of biomolecular electrostatics

NASA Astrophysics Data System (ADS)

Xie, Dexuan

2014-10-01

The Poisson-Boltzmann equation (PBE) is one widely-used implicit solvent continuum model in the calculation of electrostatic potential energy for biomolecules in ionic solvent, but its numerical solution remains a challenge due to its strong singularity and nonlinearity caused by its singular distribution source terms and exponential nonlinear terms. To effectively deal with such a challenge, in this paper, new solution decomposition and minimization schemes are proposed, together with a new PBE analysis on solution existence and uniqueness. Moreover, a PBE finite element program package is developed in Python based on the FEniCS program library and GAMer, a molecular surface and volumetric mesh generation program package. Numerical tests on proteins and a nonlinear Born ball model with an analytical solution validate the new solution decomposition and minimization schemes, and demonstrate the effectiveness and efficiency of the new PBE finite element program package.

Flammability Analysis For Actinide Oxides Packaged In 9975 Shipping Containers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laurinat, James E.; Askew, Neal M.; Hensel, Steve J.

2013-03-21

Packaging options are evaluated for compliance with safety requirements for shipment of mixed actinide oxides packaged in a 9975 Primary Containment Vessel (PCV). Radiolytic gas generation rates, PCV internal gas pressures, and shipping windows (times to reach unacceptable gas compositions or pressures after closure of the PCV) are calculated for shipment of a 9975 PCV containing a plastic bottle filled with plutonium and uranium oxides with a selected isotopic composition. G-values for radiolytic hydrogen generation from adsorbed moisture are estimated from the results of gas generation tests for plutonium oxide and uranium oxide doped with curium-244. The radiolytic generation ofmore » hydrogen from the plastic bottle is calculated using a geometric model for alpha particle deposition in the bottle wall. The temperature of the PCV during shipment is estimated from the results of finite element heat transfer analyses.« less

Efficient G0W0 using localized basis sets: a benchmark for molecules

NASA Astrophysics Data System (ADS)

Koval, Petr; Per Ljungberg, Mathias; Sanchez-Portal, Daniel

Electronic structure calculations within Hedin's GW approximation are becoming increasingly accessible to the community. In particular, as it has been shown earlier and we confirm by calculations using our MBPT_LCAO package, the computational cost of the so-called G0W0 can be made comparable to the cost of a regular Hartree-Fock calculation. In this work, we study the performance of our new implementation of G0W0 to reproduce the ionization potentials of all 117 closed-shell molecules belonging to the G2/97 test set, using a pseudo-potential starting point provided by the popular density-functional package SIESTA. Moreover, the ionization potentials and electron affinities of a set of 24 acceptor molecules are compared to experiment and to reference all-electron calculations. PK: Guipuzcoa Fellow; PK,ML,DSP: Deutsche Forschungsgemeinschaft (SFB1083); PK,DSP: MINECO MAT2013-46593-C6-2-P.

Calculation of the effective dose from natural radioactivity in soil using MCNP code.

PubMed

Krstic, D; Nikezic, D

2010-01-01

Effective dose delivered by photon emitted from natural radioactivity in soil was calculated in this work. Calculations have been done for the most common natural radionuclides in soil (238)U, (232)Th series and (40)K. A ORNL human phantoms and the Monte Carlo transport code MCNP-4B were employed to calculate the energy deposited in all organs. The effective dose was calculated according to ICRP 74 recommendations. Conversion factors of effective dose per air kerma were determined. Results obtained here were compared with other authors. Copyright 2009 Elsevier Ltd. All rights reserved.

Monte Carlo modeling of a 6 and 18 MV Varian Clinac medical accelerator for in-field and out-of-field dose calculations: development and validation

PubMed Central

Bednarz, Bryan; Xu, X George

2012-01-01

There is a serious and growing concern about the increased risk of radiation-induced second cancers and late tissue injuries associated with radiation treatment. To better understand and to more accurately quantify non-target organ doses due to scatter and leakage radiation from medical accelerators, a detailed Monte Carlo model of the medical linear accelerator is needed. This paper describes the development and validation of a detailed accelerator model of the Varian Clinac operating at 6 and 18 MV beam energies. Over 100 accelerator components have been defined and integrated using the Monte Carlo code MCNPX. A series of in-field and out-of-field dose validation studies were performed. In-field dose distributions calculated using the accelerator models were tuned to match measurement data that are considered the de facto ‘gold standard’ for the Varian Clinac accelerator provided by the manufacturer. Field sizes of 4 cm × 4 cm, 10 cm × 10 cm, 20 cm × 20 cm and 40 cm × 40 cm were considered. The local difference between calculated and measured dose on the percent depth dose curve was less than 2% for all locations. The local difference between calculated and measured dose on the dose profile curve was less than 2% in the plateau region and less than 2 mm in the penumbra region for all locations. Out-of-field dose profiles were calculated and compared to measurement data for both beam energies for field sizes of 4 cm × 4 cm, 10 cm × 10 cm and 20 cm × 20 cm. For all field sizes considered in this study, the average local difference between calculated and measured dose for the 6 and 18 MV beams was 14 and 16%, respectively. In addition, a method for determining neutron contamination in the 18 MV operating model was validated by comparing calculated in-air neutron fluence with reported calculations and measurements. The average difference between calculated and measured neutron fluence was 20%. As one of the most detailed accelerator models for both in-field and out-of-field dose calculations, the model will be combined with anatomically realistic computational patient phantoms into a computational framework to calculate non-target organ doses to patients from various radiation treatment plans. PMID:19141879

Fluence-to-dose conversion coefficients for heavy ions calculated using the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Niita, Koji

2010-04-21

The fluence to organ-absorbed-dose and effective-dose conversion coefficients for heavy ions with atomic numbers up to 28 and energies from 1 MeV/nucleon to 100 GeV/nucleon were calculated using the PHITS code coupled to the ICRP/ICRU adult reference computational phantoms, following the instruction given in ICRP Publication 103 (2007 (Oxford: Pergamon)). The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. The calculation results indicate that the effective dose can generally give a conservative estimation of the effective dose equivalent for heavy-ion exposure, although it is occasionally too conservative especially for high-energy lighter-ion irradiations. It is also found from the calculation that the conversion coefficients for the Q(y)-based effective dose equivalents are generally smaller than the corresponding Q(L)-based values because of the conceptual difference between LET and y as well as the numerical incompatibility between the Q(L) and Q(y) relationships. The calculated data of these dose conversion coefficients are very useful for the dose estimation of astronauts due to cosmic-ray exposure.

SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Folkerts, M; University of California, San Diego, La Jolla, CA; Graves, Y

Purpose: To enable an existing web application for GPU-based Monte Carlo (MC) 3D dosimetry quality assurance (QA) to compute “delivered dose” from linac logfile data. Methods: We added significant features to an IMRT/VMAT QA web application which is based on existing technologies (HTML5, Python, and Django). This tool interfaces with python, c-code libraries, and command line-based GPU applications to perform a MC-based IMRT/VMAT QA. The web app automates many complicated aspects of interfacing clinical DICOM and logfile data with cutting-edge GPU software to run a MC dose calculation. The resultant web app is powerful, easy to use, and is ablemore » to re-compute both plan dose (from DICOM data) and delivered dose (from logfile data). Both dynalog and trajectorylog file formats are supported. Users upload zipped DICOM RP, CT, and RD data and set the expected statistic uncertainty for the MC dose calculation. A 3D gamma index map, 3D dose distribution, gamma histogram, dosimetric statistics, and DVH curves are displayed to the user. Additional the user may upload the delivery logfile data from the linac to compute a 'delivered dose' calculation and corresponding gamma tests. A comprehensive PDF QA report summarizing the results can also be downloaded. Results: We successfully improved a web app for a GPU-based QA tool that consists of logfile parcing, fluence map generation, CT image processing, GPU based MC dose calculation, gamma index calculation, and DVH calculation. The result is an IMRT and VMAT QA tool that conducts an independent dose calculation for a given treatment plan and delivery log file. The system takes both DICOM data and logfile data to compute plan dose and delivered dose respectively. Conclusion: We sucessfully improved a GPU-based MC QA tool to allow for logfile dose calculation. The high efficiency and accessibility will greatly facilitate IMRT and VMAT QA.« less

Documentation of the seawater intrusion (SWI2) package for MODFLOW

USGS Publications Warehouse

Bakker, Mark; Schaars, Frans; Hughes, Joseph D.; Langevin, Christian D.; Dausman, Alyssa M.

2013-01-01

The SWI2 Package is the latest release of the Seawater Intrusion (SWI) Package for MODFLOW. The SWI2 Package allows three-dimensional vertically integrated variable-density groundwater flow and seawater intrusion in coastal multiaquifer systems to be simulated using MODFLOW-2005. Vertically integrated variable-density groundwater flow is based on the Dupuit approximation in which an aquifer is vertically discretized into zones of differing densities, separated from each other by defined surfaces representing interfaces or density isosurfaces. The numerical approach used in the SWI2 Package does not account for diffusion and dispersion and should not be used where these processes are important. The resulting differential equations are equivalent in form to the groundwater flow equation for uniform-density flow. The approach implemented in the SWI2 Package allows density effects to be incorporated into MODFLOW-2005 through the addition of pseudo-source terms to the groundwater flow equation without the need to solve a separate advective-dispersive transport equation. Vertical and horizontal movement of defined density surfaces is calculated separately using a combination of fluxes calculated through solution of the groundwater flow equation and a simple tip and toe tracking algorithm. Use of the SWI2 Package in MODFLOW-2005 only requires the addition of a single additional input file and modification of boundary heads to freshwater heads referenced to the top of the aquifer. Fluid density within model layers can be represented using zones of constant density (stratified flow) or continuously varying density (piecewise linear in the vertical direction) in the SWI2 Package. The main advantage of using the SWI2 Package instead of variable-density groundwater flow and dispersive solute transport codes, such as SEAWAT and SUTRA, is that fewer model cells are required for simulations using the SWI2 Package because every aquifer can be represented by a single layer of cells. This reduction in number of required model cells and the elimination of the need to solve the advective-dispersive transport equation results in substantial model run-time savings, which can be large for regional aquifers. The accuracy and use of the SWI2 Package is demonstrated through comparison with existing exact solutions and numerical solutions with SEAWAT. Results for an unconfined aquifer are also presented to demonstrate application of the SWI2 Package to a large-scale regional problem.

CALCULATIONAL TOOL FOR SKIN CONTAMINATION DOSE ESTIMATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

HILL, R.L.

2005-03-31

A spreadsheet calculational tool was developed to automate the calculations performed for estimating dose from skin contamination. This document reports on the design and testing of the spreadsheet calculational tool.

MCNP-based computational model for the Leksell gamma knife.

PubMed

Trnka, Jiri; Novotny, Josef; Kluson, Jaroslav

2007-01-01

We have focused on the usage of MCNP code for calculation of Gamma Knife radiation field parameters with a homogenous polystyrene phantom. We have investigated several parameters of the Leksell Gamma Knife radiation field and compared the results with other studies based on EGS4 and PENELOPE code as well as the Leksell Gamma Knife treatment planning system Leksell GammaPlan (LGP). The current model describes all 201 radiation beams together and simulates all the sources in the same time. Within each beam, it considers the technical construction of the source, the source holder, collimator system, the spherical phantom, and surrounding material. We have calculated output factors for various sizes of scoring volumes, relative dose distributions along basic planes including linear dose profiles, integral doses in various volumes, and differential dose volume histograms. All the parameters have been calculated for each collimator size and for the isocentric configuration of the phantom. We have found the calculated output factors to be in agreement with other authors' works except the case of 4 mm collimator size, where averaging over the scoring volume and statistical uncertainties strongly influences the calculated results. In general, all the results are dependent on the choice of the scoring volume. The calculated linear dose profiles and relative dose distributions also match independent studies and the Leksell GammaPlan, but care must be taken about the fluctuations within the plateau, which can influence the normalization, and accuracy in determining the isocenter position, which is important for comparing different dose profiles. The calculated differential dose volume histograms and integral doses have been compared with data provided by the Leksell GammaPlan. The dose volume histograms are in good agreement as well as integral doses calculated in small calculation matrix volumes. However, deviations in integral doses up to 50% can be observed for large volumes such as for the total skull volume. The differences observed in treatment of scattered radiation between the MC method and the LGP may be important in this case. We have also studied the influence of differential direction sampling of primary photons and have found that, due to the anisotropic sampling, doses around the isocenter deviate from each other by up to 6%. With caution about the details of the calculation settings, it is possible to employ the MCNP Monte Carlo code for independent verification of the Leksell Gamma Knife radiation field properties.

SU-F-P-21: Study of Dosimetry Accuracy of Small Passively Scattered Proton Beam Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y; Gautam, A; Kerr, M

2016-06-15

Purpose: To study the accuracy of the dose distribution of very small irregular fields of passively scattered proton beams calculated by the analytical pencil beam model of the Eclipse treatment planning system (TPS). Methods: An irregular field with a narrow region (width < 1 cm) that was used for the treatment of a small volume adjacent to a previously treated area were chosen for this investigation. Point doses at different locations inside the field were measured with a small volume ion chamber (A26, Standard Imaging). 2-D dose distributions were measured using a 2-D ion chamber array (MatriXX, IBA). All themore » measurements were done in plastic water phantom. The measured dose distributions were compared with the verification plan dose calculated in a water like phantom for the patient treatment field without the use of the compensator. Results: Point doses measured with the ion chamber in the narrowest section of the field were found to differ as much as 10% from the Eclipse calculated dose at some of the points. The 2-D dose distribution measured with the MatriXX which was validated by comparison with limited film measurement, at the proximal 95%, center of the spread out Bragg Peak and distal 90% depths agreed reasonably well with the TPS calculated dose distribution with more than 92% of the pixels passing the 2% / 2 mm dose distance agreement. Conclusion: The dose calculated by the pencil beam model of the Eclipse TPS for narrow irregular fields may not be accurate within 5% at some locations of the field, especially at the points close to the field edge due to the limitation of the dose calculation model. Overall accuracy of the calculated 2-D dose distribution was found to be acceptable for the 2%/2 mm dose/distance agreement with the measurement.« less

The Monte Carlo code MCPTV--Monte Carlo dose calculation in radiation therapy with carbon ions.

PubMed

Karg, Juergen; Speer, Stefan; Schmidt, Manfred; Mueller, Reinhold

2010-07-07

The Monte Carlo code MCPTV is presented. MCPTV is designed for dose calculation in treatment planning in radiation therapy with particles and especially carbon ions. MCPTV has a voxel-based concept and can perform a fast calculation of the dose distribution on patient CT data. Material and density information from CT are taken into account. Electromagnetic and nuclear interactions are implemented. Furthermore the algorithm gives information about the particle spectra and the energy deposition in each voxel. This can be used to calculate the relative biological effectiveness (RBE) for each voxel. Depth dose distributions are compared to experimental data giving good agreement. A clinical example is shown to demonstrate the capabilities of the MCPTV dose calculation.

Initial experience of ArcCHECK and 3DVH software for RapidArc treatment plan verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Infusino, Erminia; Mameli, Alessandra, E-mail: e.infusino@unicampus.it; Conti, Roberto

2014-10-01

The purpose of this study was to perform delivery quality assurance with ArcCHECK and 3DVH system (Sun Nuclear, FL) and to evaluate the suitability of this system for volumetric-modulated arc therapy (VMAT) (RapidArc [RA]) verification. This software calculates the delivered dose distributions in patients by perturbing the calculated dose using errors detected in fluence or planar dose measurements. The device is tested to correlate the gamma passing rate (%GP) and the composite dose predicted by 3DVH software. A total of 28 patients with prostate cancer who were treated with RA were analyzed. RA treatments were delivered to a diode arraymore » phantom (ArcCHECK), which was used to create a planned dose perturbation (PDP) file. The 3DVH analysis used the dose differences derived from comparing the measured dose with the treatment planning system (TPS)-calculated doses to perturb the initial TPS-calculated dose. The 3DVH then overlays the resultant dose on the patient's structures using the resultant “PDP” beams. Measured dose distributions were compared with the calculated ones using the gamma index (GI) method by applying the global (Van Dyk) normalization and acceptance criteria, i.e., 3%/3 mm. Paired differences tests were used to estimate statistical significance of the differences between the composite dose calculated using 3DVH and %GP. Also, statistical correlation by means of logistic regression analysis has been analyzed. Dose-volume histogram (DVH) analysis for patient plans revealed small differences between treatment plan calculations and 3DVH results for organ at risk (OAR), whereas planning target volume (PTV) of the measured plan was systematically higher than that predicted by the TPS. The t-test results between the planned and the estimated DVH values showed that mean values were incomparable (p < 0.05). The quality assurance (QA) gamma analysis 3%/3 mm showed that in all cases there were only weak-to-moderate correlations (Pearson r: 0.12 to 0.74). Moreover, clinically relevant differences increased with increasing QA passing rate, indicating that some of the largest dose differences occurred in the cases of high QA passing rates, which may be called “false negatives.” The clinical importance of any disagreement between the measured and the calculated dose is often difficult to interpret; however, beam errors (either in delivery or in TPS calculation) can affect the effectiveness of the patient dose. Further research is needed to determinate the role of a PDP-type algorithm to accurately estimate patient dose effect.« less

Performance Characteristics of an Independent Dose Verification Program for Helical Tomotherapy

PubMed Central

Chang, Isaac C. F.; Chen, Jeff; Yartsev, Slav

2017-01-01

Helical tomotherapy with its advanced method of intensity-modulated radiation therapy delivery has been used clinically for over 20 years. The standard delivery quality assurance procedure to measure the accuracy of delivered radiation dose from each treatment plan to a phantom is time-consuming. RadCalc®, a radiotherapy dose verification software, has released specifically for beta testing a module for tomotherapy plan dose calculations. RadCalc®'s accuracy for tomotherapy dose calculations was evaluated through examination of point doses in ten lung and ten prostate clinical plans. Doses calculated by the TomoHDA™ tomotherapy treatment planning system were used as the baseline. For lung cases, RadCalc® overestimated point doses in the lung by an average of 13%. Doses within the spinal cord and esophagus were overestimated by 10%. Prostate plans showed better agreement, with overestimations of 6% in the prostate, bladder, and rectum. The systematic overestimation likely resulted from limitations of the pencil beam dose calculation algorithm implemented by RadCalc®. Limitations were more severe in areas of greater inhomogeneity and less prominent in regions of homogeneity with densities closer to 1 g/cm3. Recommendations for RadCalc® dose calculation algorithms and anatomical representation were provided based on the results of the study. PMID:28974862

SU-F-T-600: Influence of Acuros XB and AAA Dose Calculation Algorithms On Plan Quality Metrics and Normal Lung Doses in Lung SBRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaparpalvi, R; Mynampati, D; Kuo, H

Purpose: To study the influence of superposition-beam model (AAA) and determinant-photon transport-solver (Acuros XB) dose calculation algorithms on the treatment plan quality metrics and on normal lung dose in Lung SBRT. Methods: Treatment plans of 10 Lung SBRT patients were randomly selected. Patients were prescribed to a total dose of 50-54Gy in 3–5 fractions (10?5 or 18?3). Doses were optimized accomplished with 6-MV using 2-arcs (VMAT). Doses were calculated using AAA algorithm with heterogeneity correction. For each plan, plan quality metrics in the categories- coverage, homogeneity, conformity and gradient were quantified. Repeat dosimetry for these AAA treatment plans was performedmore » using AXB algorithm with heterogeneity correction for same beam and MU parameters. Plan quality metrics were again evaluated and compared with AAA plan metrics. For normal lung dose, V{sub 20} and V{sub 5} to (Total lung- GTV) were evaluated. Results: The results are summarized in Supplemental Table 1. PTV volume was mean 11.4 (±3.3) cm{sup 3}. Comparing RTOG 0813 protocol criteria for conformality, AXB plans yielded on average, similar PITV ratio (individual PITV ratio differences varied from −9 to +15%), reduced target coverage (−1.6%) and increased R50% (+2.6%). Comparing normal lung doses, the lung V{sub 20} (+3.1%) and V{sub 5} (+1.5%) were slightly higher for AXB plans compared to AAA plans. High-dose spillage ((V105%PD - PTV)/ PTV) was slightly lower for AXB plans but the % low dose spillage (D2cm) was similar between the two calculation algorithms. Conclusion: AAA algorithm overestimates lung target dose. Routinely adapting to AXB for dose calculations in Lung SBRT planning may improve dose calculation accuracy, as AXB based calculations have been shown to be closer to Monte Carlo based dose predictions in accuracy and with relatively faster computational time. For clinical practice, revisiting dose-fractionation in Lung SBRT to correct for dose overestimates attributable to algorithm may very well be warranted.« less

A MULTIMODEL APPROACH FOR CALCULATING BENCHMARK DOSE

EPA Science Inventory

A Multimodel Approach for Calculating Benchmark Dose
Ramon I. Garcia and R. Woodrow Setzer

In the assessment of dose response, a number of plausible dose- response models may give fits that are consistent with the data. If no dose response formulation had been speci...

Physico-chemical behaviour of β irradiated plastic materials currently used as packagings and medical products

NASA Astrophysics Data System (ADS)

Yagoubi, N.; Baillet, A.; Pellerin, F.; Ferrier, D.

1995-11-01

The combined chromatographic technics and thermal analysis constitute an informative methodology for studying the modifications which could occur following a radiotreatment of plastic material at different doses (25 to 100 kGy). Several plastic materials used as packagings (PVC, PE, PS) were investigated. SEC method coupled with UV and DDL detections was applied to document any changes in molecular weight distribution. Reticulation and scission were the main observed degradation phenomena. These structural modifications were supported by TGA data, while the DSC provided information on modifications in crystallinity. In addition, RP-HPLC was carried out for the evaluation of the radiochemical behaviour of the additives and monomers. Firstly we demonstrated the degradation of high molecular weight phenolic antioxidants in BHT within the PEVA. Secondly, the modifications of amino 6 caproic acid and ɛ caprolactam, present in polyamid 6, depend on the irradiation doses.

Study of dose calculation on breast brachytherapy using prism TPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fendriani, Yoza; Haryanto, Freddy

2015-09-30

PRISM is one of non-commercial Treatment Planning System (TPS) and is developed at the University of Washington. In Indonesia, many cancer hospitals use expensive commercial TPS. This study aims to investigate Prism TPS which been applied to the dose distribution of brachytherapy by taking into account the effect of source position and inhomogeneities. The results will be applicable for clinical Treatment Planning System. Dose calculation has been implemented for water phantom and CT scan images of breast cancer using point source and line source. This study used point source and line source and divided into two cases. On the firstmore » case, Ir-192 seed source is located at the center of treatment volume. On the second case, the source position is gradually changed. The dose calculation of every case performed on a homogeneous and inhomogeneous phantom with dimension 20 × 20 × 20 cm{sup 3}. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm{sup 3}. The results of dose calculations using PRISM TPS were compared to literature data. From the calculation of PRISM TPS, dose rates show good agreement with Plato TPS and other study as published by Ramdhani. No deviations greater than ±4% for all case. Dose calculation in inhomogeneous and homogenous cases show similar result. This results indicate that Prism TPS is good in dose calculation of brachytherapy but not sensitive for inhomogeneities. Thus, the dose calculation parameters developed in this study were found to be applicable for clinical treatment planning of brachytherapy.« less

A clinical study of lung cancer dose calculation accuracy with Monte Carlo simulation.

PubMed

Zhao, Yanqun; Qi, Guohai; Yin, Gang; Wang, Xianliang; Wang, Pei; Li, Jian; Xiao, Mingyong; Li, Jie; Kang, Shengwei; Liao, Xiongfei

2014-12-16

The accuracy of dose calculation is crucial to the quality of treatment planning and, consequently, to the dose delivered to patients undergoing radiation therapy. Current general calculation algorithms such as Pencil Beam Convolution (PBC) and Collapsed Cone Convolution (CCC) have shortcomings in regard to severe inhomogeneities, particularly in those regions where charged particle equilibrium does not hold. The aim of this study was to evaluate the accuracy of the PBC and CCC algorithms in lung cancer radiotherapy using Monte Carlo (MC) technology. Four treatment plans were designed using Oncentra Masterplan TPS for each patient. Two intensity-modulated radiation therapy (IMRT) plans were developed using the PBC and CCC algorithms, and two three-dimensional conformal therapy (3DCRT) plans were developed using the PBC and CCC algorithms. The DICOM-RT files of the treatment plans were exported to the Monte Carlo system to recalculate. The dose distributions of GTV, PTV and ipsilateral lung calculated by the TPS and MC were compared. For 3DCRT and IMRT plans, the mean dose differences for GTV between the CCC and MC increased with decreasing of the GTV volume. For IMRT, the mean dose differences were found to be higher than that of 3DCRT. The CCC algorithm overestimated the GTV mean dose by approximately 3% for IMRT. For 3DCRT plans, when the volume of the GTV was greater than 100 cm(3), the mean doses calculated by CCC and MC almost have no difference. PBC shows large deviations from the MC algorithm. For the dose to the ipsilateral lung, the CCC algorithm overestimated the dose to the entire lung, and the PBC algorithm overestimated V20 but underestimated V5; the difference in V10 was not statistically significant. PBC substantially overestimates the dose to the tumour, but the CCC is similar to the MC simulation. It is recommended that the treatment plans for lung cancer be developed using an advanced dose calculation algorithm other than PBC. MC can accurately calculate the dose distribution in lung cancer and can provide a notably effective tool for benchmarking the performance of other dose calculation algorithms within patients.

Influence of different dose calculation algorithms on the estimate of NTCP for lung complications.

PubMed

Hedin, Emma; Bäck, Anna

2013-09-06

Due to limitations and uncertainties in dose calculation algorithms, different algorithms can predict different dose distributions and dose-volume histograms for the same treatment. This can be a problem when estimating the normal tissue complication probability (NTCP) for patient-specific dose distributions. Published NTCP model parameters are often derived for a different dose calculation algorithm than the one used to calculate the actual dose distribution. The use of algorithm-specific NTCP model parameters can prevent errors caused by differences in dose calculation algorithms. The objective of this work was to determine how to change the NTCP model parameters for lung complications derived for a simple correction-based pencil beam dose calculation algorithm, in order to make them valid for three other common dose calculation algorithms. NTCP was calculated with the relative seriality (RS) and Lyman-Kutcher-Burman (LKB) models. The four dose calculation algorithms used were the pencil beam (PB) and collapsed cone (CC) algorithms employed by Oncentra, and the pencil beam convolution (PBC) and anisotropic analytical algorithm (AAA) employed by Eclipse. Original model parameters for lung complications were taken from four published studies on different grades of pneumonitis, and new algorithm-specific NTCP model parameters were determined. The difference between original and new model parameters was presented in relation to the reported model parameter uncertainties. Three different types of treatments were considered in the study: tangential and locoregional breast cancer treatment and lung cancer treatment. Changing the algorithm without the derivation of new model parameters caused changes in the NTCP value of up to 10 percentage points for the cases studied. Furthermore, the error introduced could be of the same magnitude as the confidence intervals of the calculated NTCP values. The new NTCP model parameters were tabulated as the algorithm was varied from PB to PBC, AAA, or CC. Moving from the PB to the PBC algorithm did not require new model parameters; however, moving from PB to AAA or CC did require a change in the NTCP model parameters, with CC requiring the largest change. It was shown that the new model parameters for a given algorithm are different for the different treatment types.

gkmSVM: an R package for gapped-kmer SVM

PubMed Central

Ghandi, Mahmoud; Mohammad-Noori, Morteza; Ghareghani, Narges; Lee, Dongwon; Garraway, Levi; Beer, Michael A.

2016-01-01

Summary: We present a new R package for training gapped-kmer SVM classifiers for DNA and protein sequences. We describe an improved algorithm for kernel matrix calculation that speeds run time by about 2 to 5-fold over our original gkmSVM algorithm. This package supports several sequence kernels, including: gkmSVM, kmer-SVM, mismatch kernel and wildcard kernel. Availability and Implementation: gkmSVM package is freely available through the Comprehensive R Archive Network (CRAN), for Linux, Mac OS and Windows platforms. The C ++ implementation is available at www.beerlab.org/gkmsvm Contact: mghandi@gmail.com or mbeer@jhu.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27153639

Sensitivity of NTCP parameter values against a change of dose calculation algorithm.

PubMed

Brink, Carsten; Berg, Martin; Nielsen, Morten

2007-09-01

Optimization of radiation treatment planning requires estimations of the normal tissue complication probability (NTCP). A number of models exist that estimate NTCP from a calculated dose distribution. Since different dose calculation algorithms use different approximations the dose distributions predicted for a given treatment will in general depend on the algorithm. The purpose of this work is to test whether the optimal NTCP parameter values change significantly when the dose calculation algorithm is changed. The treatment plans for 17 breast cancer patients have retrospectively been recalculated with a collapsed cone algorithm (CC) to compare the NTCP estimates for radiation pneumonitis with those obtained from the clinically used pencil beam algorithm (PB). For the PB calculations the NTCP parameters were taken from previously published values for three different models. For the CC calculations the parameters were fitted to give the same NTCP as for the PB calculations. This paper demonstrates that significant shifts of the NTCP parameter values are observed for three models, comparable in magnitude to the uncertainties of the published parameter values. Thus, it is important to quote the applied dose calculation algorithm when reporting estimates of NTCP parameters in order to ensure correct use of the models.

Sensitivity of NTCP parameter values against a change of dose calculation algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brink, Carsten; Berg, Martin; Nielsen, Morten

2007-09-15

Optimization of radiation treatment planning requires estimations of the normal tissue complication probability (NTCP). A number of models exist that estimate NTCP from a calculated dose distribution. Since different dose calculation algorithms use different approximations the dose distributions predicted for a given treatment will in general depend on the algorithm. The purpose of this work is to test whether the optimal NTCP parameter values change significantly when the dose calculation algorithm is changed. The treatment plans for 17 breast cancer patients have retrospectively been recalculated with a collapsed cone algorithm (CC) to compare the NTCP estimates for radiation pneumonitis withmore » those obtained from the clinically used pencil beam algorithm (PB). For the PB calculations the NTCP parameters were taken from previously published values for three different models. For the CC calculations the parameters were fitted to give the same NTCP as for the PB calculations. This paper demonstrates that significant shifts of the NTCP parameter values are observed for three models, comparable in magnitude to the uncertainties of the published parameter values. Thus, it is important to quote the applied dose calculation algorithm when reporting estimates of NTCP parameters in order to ensure correct use of the models.« less

Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Sihver, Lembit; Niita, Koji

2011-03-01

Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients in the units of Gy.cm(2) and Sv.cm(2), respectively, and cosmic-ray fluxes around spacecrafts in the unit of cm(-2) s(-1). The dose conversion coefficients employed in the calculation were evaluated using the general-purpose particle and heavy ion transport code system PHITS coupled to the male and female adult reference computational phantoms, which were released as a common ICRP/ICRU publication. The cosmic-ray fluxes inside and near to spacecrafts were also calculated by PHITS, using simplified geometries. The accuracy of the obtained absorbed-dose and dose-equivalent rates was verified by various experimental data measured both inside and outside spacecrafts. The calculations quantitatively show that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents, because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors. These results demonstrate the usefulness of dose conversion coefficients in space dosimetry. © Springer-Verlag 2010

Absorbed Dose and Dose Equivalent Calculations for Modeling Effective Dose

NASA Technical Reports Server (NTRS)

Welton, Andrew; Lee, Kerry

2010-01-01

While in orbit, Astronauts are exposed to a much higher dose of ionizing radiation than when on the ground. It is important to model how shielding designs on spacecraft reduce radiation effective dose pre-flight, and determine whether or not a danger to humans is presented. However, in order to calculate effective dose, dose equivalent calculations are needed. Dose equivalent takes into account an absorbed dose of radiation and the biological effectiveness of ionizing radiation. This is important in preventing long-term, stochastic radiation effects in humans spending time in space. Monte carlo simulations run with the particle transport code FLUKA, give absorbed and equivalent dose data for relevant shielding. The shielding geometry used in the dose calculations is a layered slab design, consisting of aluminum, polyethylene, and water. Water is used to simulate the soft tissues that compose the human body. The results obtained will provide information on how the shielding performs with many thicknesses of each material in the slab. This allows them to be directly applicable to modern spacecraft shielding geometries.

Development of a web-based CT dose calculator: WAZA-ARI.

PubMed

Ban, N; Takahashi, F; Sato, K; Endo, A; Ono, K; Hasegawa, T; Yoshitake, T; Katsunuma, Y; Kai, M

2011-09-01

A web-based computed tomography (CT) dose calculation system (WAZA-ARI) is being developed based on the modern techniques for the radiation transport simulation and for software implementation. Dose coefficients were calculated in a voxel-type Japanese adult male phantom (JM phantom), using the Particle and Heavy Ion Transport code System. In the Monte Carlo simulation, the phantom was irradiated with a 5-mm-thick, fan-shaped photon beam rotating in a plane normal to the body axis. The dose coefficients were integrated into the system, which runs as Java servlets within Apache Tomcat. Output of WAZA-ARI for GE LightSpeed 16 was compared with the dose values calculated similarly using MIRD and ICRP Adult Male phantoms. There are some differences due to the phantom configuration, demonstrating the significance of the dose calculation with appropriate phantoms. While the dose coefficients are currently available only for limited CT scanner models and scanning options, WAZA-ARI will be a useful tool in clinical practice when development is finalised.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stathakis, S; Defoor, D; Saenz, D

Purpose: Stereotactic radiosurgery (SRS) outcomes are related to the delivered dose to the target and to surrounding tissue. We have commissioned a Monte Carlo based dose calculation algorithm to recalculated the delivered dose planned using pencil beam calculation dose engine. Methods: Twenty consecutive previously treated patients have been selected for this study. All plans were generated using the iPlan treatment planning system (TPS) and calculated using the pencil beam algorithm. Each patient plan consisted of 1 to 3 targets and treated using dynamically conformal arcs or intensity modulated beams. Multi-target treatments were delivered using multiple isocenters, one for each target.more » These plans were recalculated for the purpose of this study using a single isocenter. The CT image sets along with the plan, doses and structures were DICOM exported to Monaco TPS and the dose was recalculated using the same voxel resolution and monitor units. Benchmark data was also generated prior to patient calculations to assess the accuracy of the two TPS against measurements using a micro ionization chamber in solid water. Results: Good agreement, within −0.4% for Monaco and +2.2% for iPlan were observed for measurements in water phantom. Doses in patient geometry revealed up to 9.6% differences for single target plans and 9.3% for multiple-target-multiple-isocenter plans. The average dose differences for multi-target-single-isocenter plans were approximately 1.4%. Similar differences were observed for the OARs and integral dose. Conclusion: Accuracy of the beam is crucial for the dose calculation especially in the case of small fields such as those used in SRS treatments. A superior dose calculation algorithm such as Monte Carlo, with properly commissioned beam models, which is unaffected by the lack of electronic equilibrium should be preferred for the calculation of small fields to improve accuracy.« less

Recent skyshine calculations at Jefferson Lab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Degtyarenko, P.

1997-12-01

New calculations of the skyshine dose distribution of neutrons and secondary photons have been performed at Jefferson Lab using the Monte Carlo method. The dose dependence on neutron energy, distance to the neutron source, polar angle of a source neutron, and azimuthal angle between the observation point and the momentum direction of a source neutron have been studied. The azimuthally asymmetric term in the skyshine dose distribution is shown to be important in the dose calculations around high-energy accelerator facilities. A parameterization formula and corresponding computer code have been developed which can be used for detailed calculations of the skyshinemore » dose maps.« less

Real-time dose calculation and visualization for the proton therapy of ocular tumours

NASA Astrophysics Data System (ADS)

Pfeiffer, Karsten; Bendl, Rolf

2001-03-01

A new real-time dose calculation and visualization was developed as part of the new 3D treatment planning tool OCTOPUS for proton therapy of ocular tumours within a national research project together with the Hahn-Meitner Institut Berlin. The implementation resolves the common separation between parameter definition, dose calculation and evaluation and allows a direct examination of the expected dose distribution while adjusting the treatment parameters. The new tool allows the therapist to move the desired dose distribution under visual control in 3D to the appropriate place. The visualization of the resulting dose distribution as a 3D surface model, on any 2D slice or on the surface of specified ocular structures is done automatically when adapting parameters during the planning process. In addition, approximate dose volume histograms may be calculated with little extra time. The dose distribution is calculated and visualized in 200 ms with an accuracy of 6% for the 3D isodose surfaces and 8% for other objects. This paper discusses the advantages and limitations of this new approach.

A Computational Framework for Automation of Point Defect Calculations

NASA Astrophysics Data System (ADS)

Goyal, Anuj; Gorai, Prashun; Peng, Haowei; Lany, Stephan; Stevanovic, Vladan; National Renewable Energy Laboratory, Golden, Colorado 80401 Collaboration

A complete and rigorously validated open-source Python framework to automate point defect calculations using density functional theory has been developed. The framework provides an effective and efficient method for defect structure generation, and creation of simple yet customizable workflows to analyze defect calculations. The package provides the capability to compute widely accepted correction schemes to overcome finite-size effects, including (1) potential alignment, (2) image-charge correction, and (3) band filling correction to shallow defects. Using Si, ZnO and In2O3as test examples, we demonstrate the package capabilities and validate the methodology. We believe that a robust automated tool like this will enable the materials by design community to assess the impact of point defects on materials performance. National Renewable Energy Laboratory, Golden, Colorado 80401.

[Calculating Pearson residual in logistic regressions: a comparison between SPSS and SAS].

PubMed

Xu, Hao; Zhang, Tao; Li, Xiao-song; Liu, Yuan-yuan

2015-01-01

To compare the results of Pearson residual calculations in logistic regression models using SPSS and SAS. We reviewed Pearson residual calculation methods, and used two sets of data to test logistic models constructed by SPSS and STATA. One model contained a small number of covariates compared to the number of observed. The other contained a similar number of covariates as the number of observed. The two software packages produced similar Pearson residual estimates when the models contained a similar number of covariates as the number of observed, but the results differed when the number of observed was much greater than the number of covariates. The two software packages produce different results of Pearson residuals, especially when the models contain a small number of covariates. Further studies are warranted.

An ab-initio study of mechanical, dynamical and electronic properties of MgEu intermetallic

NASA Astrophysics Data System (ADS)

Kumar, S. Ramesh; Jaiganesh, G.; Jayalakshmi, V.

2018-04-01

The theoretical investigation on the mechanical, dynamical and electronic properties of MgEu in CsCl-type structure has been carried out through the ab-initio calculations within the framework of the density functional theory and the density functional perturbation theory. For the purpose, Vienna Ab initio Simulation Package and Phonopy packages were used. Our calculated ground-state properties of MgEu are in good agreement with other available results. Our computed elastic constants and phonon spectrum results suggest that MgEu is mechanically and dynamically stable up to 5 GPa. The thermodynamic quantities as a function of temperatures are also reported and discussed. The band structure, density of states and charge density also calculated to understand the electronic properties of MgEu.

Agreement between gamma passing rates using computed tomography in radiotherapy and secondary cancer risk prediction from more advanced dose calculated models

PubMed Central

Balosso, Jacques

2017-01-01

Background During the past decades, in radiotherapy, the dose distributions were calculated using density correction methods with pencil beam as type ‘a’ algorithm. The objectives of this study are to assess and evaluate the impact of dose distribution shift on the predicted secondary cancer risk (SCR), using modern advanced dose calculation algorithms, point kernel, as type ‘b’, which consider change in lateral electrons transport. Methods Clinical examples of pediatric cranio-spinal irradiation patients were evaluated. For each case, two radiotherapy treatment plans with were generated using the same prescribed dose to the target resulting in different number of monitor units (MUs) per field. The dose distributions were calculated, respectively, using both algorithms types. A gamma index (γ) analysis was used to compare dose distribution in the lung. The organ equivalent dose (OED) has been calculated with three different models, the linear, the linear-exponential and the plateau dose response curves. The excess absolute risk ratio (EAR) was also evaluated as (EAR = OED type ‘b’ / OED type ‘a’). Results The γ analysis results indicated an acceptable dose distribution agreement of 95% with 3%/3 mm. Although, the γ-maps displayed dose displacement >1 mm around the healthy lungs. Compared to type ‘a’, the OED values from type ‘b’ dose distributions’ were about 8% to 16% higher, leading to an EAR ratio >1, ranged from 1.08 to 1.13 depending on SCR models. Conclusions The shift of dose calculation in radiotherapy, according to the algorithm, can significantly influence the SCR prediction and the plan optimization, since OEDs are calculated from DVH for a specific treatment. The agreement between dose distribution and SCR prediction depends on dose response models and epidemiological data. In addition, the γ passing rates of 3%/3 mm does not translate the difference, up to 15%, in the predictions of SCR resulting from alternative algorithms. Considering that modern algorithms are more accurate, showing more precisely the dose distributions, but that the prediction of absolute SCR is still very imprecise, only the EAR ratio could be used to rank radiotherapy plans. PMID:28811995

SU-E-T-538: Evaluation of IMRT Dose Calculation Based on Pencil-Beam and AAA Algorithms.

PubMed

Yuan, Y; Duan, J; Popple, R; Brezovich, I

2012-06-01

To evaluate the accuracy of dose calculation for intensity modulated radiation therapy (IMRT) based on Pencil Beam (PB) and Analytical Anisotropic Algorithm (AAA) computation algorithms. IMRT plans of twelve patients with different treatment sites, including head/neck, lung and pelvis, were investigated. For each patient, dose calculation with PB and AAA algorithms using dose grid sizes of 0.5 mm, 0.25 mm, and 0.125 mm, were compared with composite-beam ion chamber and film measurements in patient specific QA. Discrepancies between the calculation and the measurement were evaluated by percentage error for ion chamber dose and γ〉l failure rate in gamma analysis (3%/3mm) for film dosimetry. For 9 patients, ion chamber dose calculated with AAA-algorithms is closer to ion chamber measurement than that calculated with PB algorithm with grid size of 2.5 mm, though all calculated ion chamber doses are within 3% of the measurements. For head/neck patients and other patients with large treatment volumes, γ〉l failure rate is significantly reduced (within 5%) with AAA-based treatment planning compared to generally more than 10% with PB-based treatment planning (grid size=2.5 mm). For lung and brain cancer patients with medium and small treatment volumes, γ〉l failure rates are typically within 5% for both AAA and PB-based treatment planning (grid size=2.5 mm). For both PB and AAA-based treatment planning, improvements of dose calculation accuracy with finer dose grids were observed in film dosimetry of 11 patients and in ion chamber measurements for 3 patients. AAA-based treatment planning provides more accurate dose calculation for head/neck patients and other patients with large treatment volumes. Compared with film dosimetry, a γ〉l failure rate within 5% can be achieved for AAA-based treatment planning. © 2012 American Association of Physicists in Medicine.

A new concept of pencil beam dose calculation for 40-200 keV photons using analytical dose kernels.

PubMed

Bartzsch, Stefan; Oelfke, Uwe

2013-11-01

The advent of widespread kV-cone beam computer tomography in image guided radiation therapy and special therapeutic application of keV photons, e.g., in microbeam radiation therapy (MRT) require accurate and fast dose calculations for photon beams with energies between 40 and 200 keV. Multiple photon scattering originating from Compton scattering and the strong dependence of the photoelectric cross section on the atomic number of the interacting tissue render these dose calculations by far more challenging than the ones established for corresponding MeV beams. That is why so far developed analytical models of kV photon dose calculations fail to provide the required accuracy and one has to rely on time consuming Monte Carlo simulation techniques. In this paper, the authors introduce a novel analytical approach for kV photon dose calculations with an accuracy that is almost comparable to the one of Monte Carlo simulations. First, analytical point dose and pencil beam kernels are derived for homogeneous media and compared to Monte Carlo simulations performed with the Geant4 toolkit. The dose contributions are systematically separated into contributions from the relevant orders of multiple photon scattering. Moreover, approximate scaling laws for the extension of the algorithm to inhomogeneous media are derived. The comparison of the analytically derived dose kernels in water showed an excellent agreement with the Monte Carlo method. Calculated values deviate less than 5% from Monte Carlo derived dose values, for doses above 1% of the maximum dose. The analytical structure of the kernels allows adaption to arbitrary materials and photon spectra in the given energy range of 40-200 keV. The presented analytical methods can be employed in a fast treatment planning system for MRT. In convolution based algorithms dose calculation times can be reduced to a few minutes.

Ray-tracing in three dimensions for calculation of radiation-dose calculations. Master's thesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kennedy, D.R.

1986-05-27

This thesis addresses several methods of calculating the radiation-dose distribution for use by technicians or clinicians in radiation-therapy treatment planning. It specifically covers the calculation of the effective pathlength of the radiation beam for use in beam models representing the dose distribution. A two-dimensional method by Bentley and Milan is compared to the method of Strip Trees developed by Duda and Hart and then a three-dimensional algorithm built to perform the calculations in three dimensions. The use of PRISMS conforms easily to the obtained CT Scans and provides a means of only doing two-dimensional ray-tracing while performing three-dimensional dose calculations.more » This method is already being applied and used in actual calculations.« less

Target prices for mass production of tyrosine kinase inhibitors for global cancer treatment.

PubMed

Hill, Andrew; Gotham, Dzintars; Fortunak, Joseph; Meldrum, Jonathan; Erbacher, Isabelle; Martin, Manuel; Shoman, Haitham; Levi, Jacob; Powderly, William G; Bower, Mark

2016-01-27

To calculate sustainable generic prices for 4 tyrosine kinase inhibitors (TKIs). TKIs have proven survival benefits in the treatment of several cancers, including chronic myeloid leukaemia, breast, liver, renal and lung cancer. However, current high prices are a barrier to treatment. Mass production of low-cost generic antiretrovirals has led to over 13 million people being on HIV/AIDS treatment worldwide. This analysis estimates target prices for generic TKIs, assuming similar methods of mass production. Four TKIs with patent expiry dates in the next 5 years were selected for analysis: imatinib, erlotinib, lapatinib and sorafenib. Chemistry, dosing, published data on per-kilogram pricing for commercial transactions of active pharmaceutical ingredient (API), and quotes from manufacturers were used to estimate costs of production. Analysis included costs of excipients, formulation, packaging, shipping and a 50% profit margin. Target prices were compared with current prices. Global numbers of patients eligible for treatment with each TKI were estimated. API costs per kg were $347-$746 for imatinib, $2470 for erlotinib, $4671 for lapatinib, and $3000 for sorafenib. Basing on annual dose requirements, costs of formulation/packaging and a 50% profit margin, target generic prices per person-year were $128-$216 for imatinib, $240 for erlotinib, $1450 for sorafenib, and $4020 for lapatinib. Over 1 million people would be newly eligible to start treatment with these TKIs annually. Mass generic production of several TKIs could achieve treatment prices in the range of $128-$4020 per person-year, versus current US prices of $75161-$139,138. Generic TKIs could allow significant savings and scaling-up of treatment globally, for over 1 million eligible patients. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

SU-E-T-632: Preliminary Study On Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, L; Eldib, A; Li, J

Purpose: Uneven nose surfaces and air cavities underneath and the use of bolus present complexity and dose uncertainty when using a single electron energy beam to plan treatments of nose skin with a pencil beam-based planning system. This work demonstrates more accurate dose calculation and more optimal planning using energy and intensity modulated electron radiotherapy (MERT) delivered with a pMLC. Methods: An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reducemore » the scatter-caused penumbra, a short SSD (61 cm) was used. Our previous work demonstrates good agreement in percentage depth dose and off-axis dose between calculations and film measurement for various field sizes. A MERT plan was generated for treating the nose skin using a patient geometry and a dose volume histogram (DVH) was obtained. The work also shows the comparison of 2D dose distributions between a clinically used conventional single electron energy plan and the MERT plan. Results: The MERT plan resulted in improved target dose coverage as compared to the conventional plan, which demonstrated a target dose deficit at the field edge. The conventional plan showed higher dose normal tissue irradiation underneath the nose skin while the MERT plan resulted in improved conformity and thus reduces normal tissue dose. Conclusion: This preliminary work illustrates that MC-based MERT planning is a promising technique in treating nose skin, not only providing more accurate dose calculation, but also offering an improved target dose coverage and conformity. In addition, this technique may eliminate the necessity of bolus, which often produces dose delivery uncertainty due to the air gaps that may exist between the bolus and skin.« less

Calculation of organ doses from breast cancer radiotherapy: a Monte Carlo study

PubMed Central

Berris, T.; Mazonakis, M.; Stratakis, J.; Tzedakis, A.; Fasoulaki, A.

2013-01-01

The current study aimed to: a) utilize Monte Carlo simulation methods for the assessment of radiation doses imparted to all organs at risk to develop secondary radiation induced cancer, for patients undergoing radiotherapy for breast cancer; and b) evaluate the effect of breast size on dose to organs outside the irradiation field. A simulated linear accelerator model was generated. The in‐field accuracy of the simulated photon beam properties was verified against percentage depth dose (PDD) and dose profile measurements on an actual water phantom. Off‐axis dose calculations were verified with thermoluminescent dosimetry (TLD) measurements on a humanoid physical phantom. An anthropomorphic mathematical phantom was used to simulate breast cancer radiotherapy with medial and lateral fields. The effect of breast size on the calculated organ dose was investigated. Local differences between measured and calculated PDDs and dose profiles did not exceed 2% for the points at depths beyond the depth of maximum dose and the plateau region of the profile, respectively. For the penumbral regions of the dose profiles, the distance to agreement (DTA) did not exceed 2 mm. The mean difference between calculated out‐of‐field doses and TLD measurements was 11.4%±5.9%. The calculated doses to peripheral organs ranged from 2.32 cGy up to 161.41 cGy depending on breast size and thus the field dimensions applied, as well as the proximity of the organs to the primary beam. An increase to the therapeutic field area by 50% to account for the large breast led to a mean organ dose elevation by up to 85.2% for lateral exposure. The contralateral breast dose ranged between 1.4% and 1.6% of the prescribed dose to the tumor. Breast size affects dose deposition substantially. PACS numbers: 87.10.rt, 87.56.bd, 87.53.Bn, 87.55.K‐, 87.55.ne, 87.56.jf, 87.56.J‐ PMID:23318389

Sub-second pencil beam dose calculation on GPU for adaptive proton therapy

NASA Astrophysics Data System (ADS)

da Silva, Joakim; Ansorge, Richard; Jena, Rajesh

2015-06-01

Although proton therapy delivered using scanned pencil beams has the potential to produce better dose conformity than conventional radiotherapy, the created dose distributions are more sensitive to anatomical changes and patient motion. Therefore, the introduction of adaptive treatment techniques where the dose can be monitored as it is being delivered is highly desirable. We present a GPU-based dose calculation engine relying on the widely used pencil beam algorithm, developed for on-line dose calculation. The calculation engine was implemented from scratch, with each step of the algorithm parallelized and adapted to run efficiently on the GPU architecture. To ensure fast calculation, it employs several application-specific modifications and simplifications, and a fast scatter-based implementation of the computationally expensive kernel superposition step. The calculation time for a skull base treatment plan using two beam directions was 0.22 s on an Nvidia Tesla K40 GPU, whereas a test case of a cubic target in water from the literature took 0.14 s to calculate. The accuracy of the patient dose distributions was assessed by calculating the γ-index with respect to a gold standard Monte Carlo simulation. The passing rates were 99.2% and 96.7%, respectively, for the 3%/3 mm and 2%/2 mm criteria, matching those produced by a clinical treatment planning system.

SU-F-T-517: Determining the Tissue Equivalence of a Brass Mesh Bolus in a Reconstructed Chest Wall Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shekel, E; Epstein, D; Levin, D

2016-06-15

Purpose: To determine the tissue equivalence of a brass mesh bolus (RPD) in the setting of a reconstructed chest wall irradiation Methods: We measured breast skin dose delivered by a tangential field plan on an anthropomorphic phantom using Mosfet and nanoDot (Landauer) dosimeters in five different locations on the breast. We also measured skin dose using no bolus, 5mm and 10 mm superflab bolus. In the Eclipse treatment planning system (Varian, Palo Alto, CA) we calculated skin dose for different bolus thicknesses, ranging from 0 to 10 mm, in order to evaluate which calculation best matches the brass mesh measurements,more » as the brass mesh cannot be simulated due to artefacts.Finally, we measured depth dose behavior with the brass mesh bolus to verify that the bolus does not affect the dose to the breast itself beyond the build-up region. Results: Mosfet and nanoDot measurements were consistent with each other.As expected, skin dose measurements with no bolus had the least agreement with Eclipse calculation, while measurements for 5 and 10 mm agreed well with the calculation despite the difficulty in conforming superflab bolus to the breast contour. For the brass mesh the best agreement was for 3 mm bolus Eclipse calculation. For Mosfets, the average measurement was 90.8% of the expected dose, and for nanoDots 88.33% compared to 83.34%, 88.64% and 93.94% (2,3 and 5 mm bolus calculation respectively).The brass mesh bolus increased skin dose by approximately 25% but there was no dose increase beyond the build-up region. Conclusion: Brass mesh bolus is most equivalent to a 3 mm bolus, and does not affect the dose beyond the build-up region. The brass mesh cannot be directly calculated in Eclipse, hence a 3mm bolus calculation is a good reflection of the dose response to the brass mesh bolus.« less

TU-D-201-05: Validation of Treatment Planning Dose Calculations: Experience Working with MPPG 5.a

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, J; Park, J; Kim, L

2016-06-15

Purpose: Newly published medical physics practice guideline (MPPG 5.a.) has set the minimum requirements for commissioning and QA of treatment planning dose calculations. We present our experience in the validation of a commercial treatment planning system based on MPPG 5.a. Methods: In addition to tests traditionally performed to commission a model-based dose calculation algorithm, extensive tests were carried out at short and extended SSDs, various depths, oblique gantry angles and off-axis conditions to verify the robustness and limitations of a dose calculation algorithm. A comparison between measured and calculated dose was performed based on validation tests and evaluation criteria recommendedmore » by MPPG 5.a. An ion chamber was used for the measurement of dose at points of interest, and diodes were used for photon IMRT/VMAT validations. Dose profiles were measured with a three-dimensional scanning system and calculated in the TPS using a virtual water phantom. Results: Calculated and measured absolute dose profiles were compared at each specified SSD and depth for open fields. The disagreement is easily identifiable with the difference curve. Subtle discrepancy has revealed the limitation of the measurement, e.g., a spike at the high dose region and an asymmetrical penumbra observed on the tests with an oblique MLC beam. The excellent results we had (> 98% pass rate on 3%/3mm gamma index) on the end-to-end tests for both IMRT and VMAT are attributed to the quality beam data and the good understanding of the modeling. The limitation of the model and the uncertainty of measurement were considered when comparing the results. Conclusion: The extensive tests recommended by the MPPG encourage us to understand the accuracy and limitations of a dose algorithm as well as the uncertainty of measurement. Our experience has shown how the suggested tests can be performed effectively to validate dose calculation models.« less

Determination of dose distributions and parameter sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, B.A.; Farris, W.T.; Simpson, J.C.

1992-12-01

A series of scoping calculations has been undertaken to evaluate the absolute and relative contribution of different radionuclides and exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 005) examined the contributions of numerous parameters to the uncertainty distribution of doses calculated for environmental exposures and accumulation in foods. This study builds on the work initiated in the first scoping study of iodine in cow's milk and the third scoping study, which added additional pathways. Addressed in this calculation were the contributions to thyroid dose ofmore » infants from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows' milk from Feeding Regime 1 as described in Calculation 001.« less

The choice of statistical methods for comparisons of dosimetric data in radiotherapy.

PubMed

Chaikh, Abdulhamid; Giraud, Jean-Yves; Perrin, Emmanuel; Bresciani, Jean-Pierre; Balosso, Jacques

2014-09-18

Novel irradiation techniques are continuously introduced in radiotherapy to optimize the accuracy, the security and the clinical outcome of treatments. These changes could raise the question of discontinuity in dosimetric presentation and the subsequent need for practice adjustments in case of significant modifications. This study proposes a comprehensive approach to compare different techniques and tests whether their respective dose calculation algorithms give rise to statistically significant differences in the treatment doses for the patient. Statistical investigation principles are presented in the framework of a clinical example based on 62 fields of radiotherapy for lung cancer. The delivered doses in monitor units were calculated using three different dose calculation methods: the reference method accounts the dose without tissues density corrections using Pencil Beam Convolution (PBC) algorithm, whereas new methods calculate the dose with tissues density correction for 1D and 3D using Modified Batho (MB) method and Equivalent Tissue air ratio (ETAR) method, respectively. The normality of the data and the homogeneity of variance between groups were tested using Shapiro-Wilks and Levene test, respectively, then non-parametric statistical tests were performed. Specifically, the dose means estimated by the different calculation methods were compared using Friedman's test and Wilcoxon signed-rank test. In addition, the correlation between the doses calculated by the three methods was assessed using Spearman's rank and Kendall's rank tests. The Friedman's test showed a significant effect on the calculation method for the delivered dose of lung cancer patients (p <0.001). The density correction methods yielded to lower doses as compared to PBC by on average (-5 ± 4.4 SD) for MB and (-4.7 ± 5 SD) for ETAR. Post-hoc Wilcoxon signed-rank test of paired comparisons indicated that the delivered dose was significantly reduced using density-corrected methods as compared to the reference method. Spearman's and Kendall's rank tests indicated a positive correlation between the doses calculated with the different methods. This paper illustrates and justifies the use of statistical tests and graphical representations for dosimetric comparisons in radiotherapy. The statistical analysis shows the significance of dose differences resulting from two or more techniques in radiotherapy.

Monte Carlo calculated doses to treatment volumes and organs at risk for permanent implant lung brachytherapy

NASA Astrophysics Data System (ADS)

Sutherland, J. G. H.; Furutani, K. M.; Thomson, R. M.

2013-10-01

Iodine-125 (125I) and Caesium-131 (131Cs) brachytherapy have been used with sublobar resection to treat stage I non-small cell lung cancer and other radionuclides, 169Yb and 103Pd, are considered for these treatments. This work investigates the dosimetry of permanent implant lung brachytherapy for a range of source energies and various implant sites in the lung. Monte Carlo calculated doses are calculated in a patient CT-derived computational phantom using the EGsnrc user-code BrachyDose. Calculations are performed for 103Pd, 125I, 131Cs seeds and 50 and 100 keV point sources for 17 implant positions. Doses to treatment volumes, ipsilateral lung, aorta, and heart are determined and compared to those determined using the TG-43 approach. Considerable variation with source energy and differences between model-based and TG-43 doses are found for both treatment volumes and organs. Doses to the heart and aorta generally increase with increasing source energy. TG-43 underestimates the dose to the heart and aorta for all implants except those nearest to these organs where the dose is overestimated. Results suggest that model-based dose calculations are crucial for selecting prescription doses, comparing clinical endpoints, and studying radiobiological effects for permanent implant lung brachytherapy.

Which community care for patients with schizophrenic disorders? Packages of care provided by Departments of Mental Health in Lombardy (Italy).

PubMed

Lora, Antonio; Cosentino, Ugo; Gandini, Anna; Zocchetti, Carlo

2007-01-01

The treatment of schizophrenic disorders is the most important challenge for community care. The analysis focuses on packages of care provided to 23.602 patients with a ICD-10 diagnosis of schizophrenic disorder and treated in 2001 by the Departments of Mental Health in Lombardy, Italy. Packages of care refer to a mix of treatments provided to each patient during the year by different settings. Direct costs of the packages were calculated. Linear Discriminant Analysis has been used to link socio-demographic and diagnostic sub-groups of the patients to packages of care. People with schizophrenic disorders received relatively few care packages: only four packages involved more than 5%. Two thirds of the patients received only care provided by Community Mental Health Centres. In the other two packages with a percentage over 5%, the activity was provided by CMHCs, jointly with General Hospitals or Day Care Facilities. Complex care packages were rare (only 6%). As well as the intensity, also the variety of care provided by CMHCs increased with the complexity of care packages. In Lombardy more than half of the resources were spent for schizophrenia. The range of the costs per package was very wide. LDA failed to link characteristics of the patients to packages of care. Care packages are useful tools to understand better how mental health system works, how resources have been spent and to point out problems in the quality of care.

Radiation sterilization of aseptically manufactured products.

PubMed

Fairand, Barry P; Fidopiastis, Niki

2010-01-01

This paper discusses an approach for establishing a sterilization dose for an aseptically processed product after the product is in its final packaged state, in other words, terminal sterilization. It applies to aseptic processes where the fill/finish operation is conducted in a closed system using isolator or restricted access barrier technology, that is, no human intervention. The example that is given in this paper uses gamma radiation as the sterilizing agent. Other forms of radiation such as high-energy electrons or X-rays also could serve as the sterilizing agent. The proposed approach involves irradiation of the aseptically processed product at very low doses of radiation, which is possible due to the extremely low levels of bioburden that may be present on the product following a fill/finish operation. Rather than sacrificing a large number of product units that may be required to obtain a statistically significant sampling of the product for bioburden analysis and other test purposes, the test unit is a surrogate consisting of actual pharmaceutical product that was inoculated with a highly radiation-resistant micro-organism. Selection of the microorganism was based on analysis of a library of environmental monitoring data taken from the aseptic area. Because of microbial diversity between different aseptic processing facilities, selection of the test microorganism would depend on the aseptic area under study. The approach that is discussed in this paper addresses selection and preparation of the surrogate, test of sterility of the surrogate following irradiation, determination of the radiation resistance of the test microorganism, and application of the approach to calculate a sterilization dose that is less than 10 kGy. At this low dose, it may be possible to terminally sterilize radiation-sensitive pharmaceutical products, for example, those in liquid form. Additional studies are warranted to determine the general applicability of the proposed approach.

Cardiovascular drugs consumption--comparison between two Croatian regions, City of Zagreb and Lika-Senj County.

PubMed

Jurković, Drazen; Stimac, Danijela; Bajramović, Dubravko; Tiljak, Hrvoje; Stevanović, Ranko

2014-06-01

The aim of this paper is to determine the differences in the outpatient consumption of cardiovascular drugs between Croatian regions: the City of Zagreb and Lika-Senj County. The data on the number of packages and the purchase price for each drug have been obtained from all pharmacies in Lika-Senj County and all pharmacies in the City of Zagreb. Defined daily doses/1000 inhabitants/day (DDD/1000/day) was calculated for every drug in accordance with its code name and Anatomical Therapeutic Chemical/Defined Daily Dose (ATC/DDD) index of the World Health Organization (WHO) for 2007. For drug combinations without defined daily doses, equivalent doses (ED) were used. The quality of drug prescribing within the group of cardiovascular drugs was assessed using the Drug Utilization (DU90%) method and the adherence of the DU90% segment to the guidelines for prescribing individual drug groups. The statistical significance of differences in results between the City of Zagreb and Lika-Senj County was tested using the chi-square test at the level of statistical significance p < 0.05. The comparison of the share of the five most often prescribed drug groups in Lika-Senj County has shown statistically significant differences when compared to the City of Zagreb (chi2 = 28.93, df = 4, p < 0.001). The total outpatient consumption of cardiovascular drugs in the City of Zagreb and Lika-Senj County differs significantly. The consumption, quality of prescribing drugs and cost/DDD in the City of Zagreb is higher than in Lika-Senj County; in the City of Zagreb, newer and more expensive drugs are prescribed to a higher extent.

Preventing medication errors in cancer chemotherapy.

PubMed

Cohen, M R; Anderson, R W; Attilio, R M; Green, L; Muller, R J; Pruemer, J M

1996-04-01

Recommendations for preventing medication errors in cancer chemotherapy are made. Before a health care provider is granted privileges to prescribe, dispense, or administer antineoplastic agents, he or she should undergo a tailored educational program and possibly testing or certification. Appropriate reference materials should be developed. Each institution should develop a dose-verification process with as many independent checks as possible. A detailed checklist covering prescribing, transcribing, dispensing, and administration should be used. Oral orders are not acceptable. All doses should be calculated independently by the physician, the pharmacist, and the nurse. Dosage limits should be established and a review process set up for doses that exceed the limits. These limits should be entered into pharmacy computer systems, listed on preprinted order forms, stated on the product packaging, placed in strategic locations in the institution, and communicated to employees. The prescribing vocabulary must be standardized. Acronyms, abbreviations, and brand names must be avoided and steps taken to avoid other sources of confusion in the written orders, such as trailing zeros. Preprinted antineoplastic drug order forms containing checklists can help avoid errors. Manufacturers should be encouraged to avoid or eliminate ambiguities in drug names and dosing information. Patients must be educated about all aspects of their cancer chemotherapy, as patients represent a last line of defense against errors. An interdisciplinary team at each practice site should review every medication error reported. Pharmacists should be involved at all sites where antineoplastic agents are dispensed. Although it may not be possible to eliminate all medication errors in cancer chemotherapy, the risk can be minimized through specific steps. Because of their training and experience, pharmacists should take the lead in this effort.

[Anaphylaxis related to measles, mumps, and rubella vaccine in Santa Catarina State, Brazil, 2014 and 2015].

PubMed

Fantinato, Francieli Fontana Sutile Tardetti; Vargas, Alexander; Carvalho, Sandra Maria Deotti; Domingues, Carla Magda Allan Santos; Barreto, Gisele; Fialho, Arieli Schiessl; Silva, Roselita Heinen da; Saad, Eduardo; Agredo, Ivonne Natalia Solarte

2018-03-12

The study aimed to describe cases and verify the frequency of anaphylaxis related to measles, mumps, and rubella (MMR) vaccine produced by manufacturer A and to assess associated risk factors. This was a case-control study (1:4) in Santa Catarina State, Brazil, from July 14, 2014, to January 12, 2015, in children from one year to less than five years of age, vaccinated with MMR and reported with anaphylaxis, while the controls were without anaphylaxis. The measure of association was odds ratio (OR) with 95% confidence interval (95%CI), using the chi-square and Fisher's exact tests. Anaphylaxis rates were calculated per doses distributed/administered. Fifteen cases and 60 controls were interviewed in 12 municipalities (counties). Anaphylaxis rates were 2.46 and 5.05 cases per 100,000 doses distributed and administered, respectively. Among the cases of anaphylaxis, eight (53.4%) were males, and among the controls, 36 (60%), with p = 0.64. The bivariate analysis of anaphylaxis and cow's milk protein allergy (CMPA) showed OR = 51.62, with p = 0.00002 and 95%CI: 5.59-476.11. The variables family food allergy, breastfeeding, previous post-vaccine adverse event (PVAE), and simultaneous vaccination were not statistically significant (p = 0.48; p = 1.00; p = 0.49; p = 0.61). Anaphylaxis rates per doses distributed/administered exceeded 1/100,000 doses administered (expected rate). Anaphylaxis and CMPA showed a statistically significant association. No statistically significant associations were found with simultaneous vaccination, breastfeeding, family food allergy, or history of PVAE. the manufacturer should specify the product's components in the package insert, and children with a history of CMPA should not be vaccinated with this vaccine.

Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study

NASA Astrophysics Data System (ADS)

Yepes, Pablo P.; Eley, John G.; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

2016-04-01

Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

Dosimetric evaluation of a Monte Carlo IMRT treatment planning system incorporating the MIMiC

NASA Astrophysics Data System (ADS)

Rassiah-Szegedi, P.; Fuss, M.; Sheikh-Bagheri, D.; Szegedi, M.; Stathakis, S.; Lancaster, J.; Papanikolaou, N.; Salter, B.

2007-12-01

The high dose per fraction delivered to lung lesions in stereotactic body radiation therapy (SBRT) demands high dose calculation and delivery accuracy. The inhomogeneous density in the thoracic region along with the small fields used typically in intensity-modulated radiation therapy (IMRT) treatments poses a challenge in the accuracy of dose calculation. In this study we dosimetrically evaluated a pre-release version of a Monte Carlo planning system (PEREGRINE 1.6b, NOMOS Corp., Cranberry Township, PA), which incorporates the modeling of serial tomotherapy IMRT treatments with the binary multileaf intensity modulating collimator (MIMiC). The aim of this study is to show the validation process of PEREGRINE 1.6b since it was used as a benchmark to investigate the accuracy of doses calculated by a finite size pencil beam (FSPB) algorithm for lung lesions treated on the SBRT dose regime via serial tomotherapy in our previous study. Doses calculated by PEREGRINE were compared against measurements in homogeneous and inhomogeneous materials carried out on a Varian 600C with a 6 MV photon beam. Phantom studies simulating various sized lesions were also carried out to explain some of the large dose discrepancies seen in the dose calculations with small lesions. Doses calculated by PEREGRINE agreed to within 2% in water and up to 3% for measurements in an inhomogeneous phantom containing lung, bone and unit density tissue.

Calculation of Glucose Dose for Intraperitoneal Glucose Tolerance Tests in Lean and Obese Mice.

PubMed

Jørgensen, Mikkel S; Tornqvist, Kristina S; Hvid, Henning

2017-01-01

Glucose tolerance tests are used frequently in nonclinical research with laboratory animals, for example during characterization of obese phenotypes. Despite published standard operating procedures for glucose tolerance tests in rodents, how glucose doses should be calculated when obese and lean animals are compared is not well documented. Typically the glucose dose is calculated as 2 g/kg body weight, regardless of body composition. With this approach, obese mice receive larger glucose doses than do lean animals, potentially leading to overestimation of glucose intolerance in obese animals. In this study, we performed intraperitoneal glucose tolerance tests in mice with diet-induced obesity and their lean controls, with glucose doses based on either the total body weight or the lean body mass of the animals. To determine glucose tolerance, we determined the blood glucose AUC during the glucose tolerance test. We found that the blood glucose AUC was increased significantly in obese mice compared with lean mice by 75% on average when glucose was dosed according to the lean body mass and by 87% when the glucose dose was calculated according to total body weight. Therefore, mice with diet-induced obesity were approximately equally glucose intolerant between the 2 dose-calculation protocols. However, we recommend calculating the glucose dose according to the lean body mass of the mice, because doing so eliminates the concern regarding overdosing of obese animals.

Predicting Pharmacokinetic Stability by Multiple Oral Administration of Atypical Antipsychotics

PubMed Central

Aoki, Kazuo; Sakiyama, Yojiro; Ohnishi, Takashi; Sugita, Makoto

2013-01-01

Lower fluctuation, i.e., lower peak-to-trough plasma-concentration variation at steady-state pharmacokinetics, has several advantages for the treatment of schizophrenia with antipsychotics. The reduction of peak concentration can decrease the risk of dose-dependent side effects, such as extrapyramidal symptom and somnolence, and by contrast the increase in trough concentration can decrease the incidence of lack of efficacy due to subtherapeutic drug concentration. Using a one-compartment simulation technique with pharmacokinetic parameters of each atypical antipsychotic collected from package inserts, the fluctuation index was calculated. Among the antipsychotics, the indices varied from 0.018 to 1.9, depending on dosing regimens, formulations and several pharmacokinetic properties. The order of simulated fluctuation index is active-moiety aripiprazole (b.i.d.)

Argonne National Laboratory-East site environmental report for calendar year 1998.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golchert, N.W.; Kolzow, R.G.

1999-08-26

This report discusses the results of the environmental protection program at Argonne National Laboratory-East (ANL-E) for 1998. To evaluate the effects of ANL-E operations on the environment, samples of environmental media collected on the site, at the site boundary, and off the ANL-E site were analyzed and compared with applicable guidelines and standards. A variety of radionuclides were measured in air, surface water, on-site groundwater, and bottom sediment samples. In addition, chemical constituents in surface water, groundwater, and ANL-E effluent water were analyzed. External penetrating radiation doses were measured, and the potential for radiation exposure to off-site population groups wasmore » estimated. Results are interpreted in terms of the origin of the radioactive and chemical substances (i.e., natural, fallout, ANL-E, and other) and are compared with applicable environmental quality standards. A US Department of Energy dose calculation methodology, based on International Commission on Radiological Protection recommendations and the US Environmental Protection Agency's CAP-88 (Clean Air Act Assessment Package-1988) computer code, was used in preparing this report. The status of ANL-E environmental protection activities with respect to the various laws and regulations that govern waste handling and disposal is discussed, along with the progress of environmental corrective actions and restoration projects.« less

Fast dose kernel interpolation using Fourier transform with application to permanent prostate brachytherapy dosimetry.

PubMed

Liu, Derek; Sloboda, Ron S

2014-05-01

Boyer and Mok proposed a fast calculation method employing the Fourier transform (FT), for which calculation time is independent of the number of seeds but seed placement is restricted to calculation grid points. Here an interpolation method is described enabling unrestricted seed placement while preserving the computational efficiency of the original method. The Iodine-125 seed dose kernel was sampled and selected values were modified to optimize interpolation accuracy for clinically relevant doses. For each seed, the kernel was shifted to the nearest grid point via convolution with a unit impulse, implemented in the Fourier domain. The remaining fractional shift was performed using a piecewise third-order Lagrange filter. Implementation of the interpolation method greatly improved FT-based dose calculation accuracy. The dose distribution was accurate to within 2% beyond 3 mm from each seed. Isodose contours were indistinguishable from explicit TG-43 calculation. Dose-volume metric errors were negligible. Computation time for the FT interpolation method was essentially the same as Boyer's method. A FT interpolation method for permanent prostate brachytherapy TG-43 dose calculation was developed which expands upon Boyer's original method and enables unrestricted seed placement. The proposed method substantially improves the clinically relevant dose accuracy with negligible additional computation cost, preserving the efficiency of the original method.

Accuracy of radiotherapy dose calculations based on cone-beam CT: comparison of deformable registration and image correction based methods

NASA Astrophysics Data System (ADS)

Marchant, T. E.; Joshi, K. D.; Moore, C. J.

2018-03-01

Radiotherapy dose calculations based on cone-beam CT (CBCT) images can be inaccurate due to unreliable Hounsfield units (HU) in the CBCT. Deformable image registration of planning CT images to CBCT, and direct correction of CBCT image values are two methods proposed to allow heterogeneity corrected dose calculations based on CBCT. In this paper we compare the accuracy and robustness of these two approaches. CBCT images for 44 patients were used including pelvis, lung and head & neck sites. CBCT HU were corrected using a ‘shading correction’ algorithm and via deformable registration of planning CT to CBCT using either Elastix or Niftyreg. Radiotherapy dose distributions were re-calculated with heterogeneity correction based on the corrected CBCT and several relevant dose metrics for target and OAR volumes were calculated. Accuracy of CBCT based dose metrics was determined using an ‘override ratio’ method where the ratio of the dose metric to that calculated on a bulk-density assigned version of the same image is assumed to be constant for each patient, allowing comparison to the patient’s planning CT as a gold standard. Similar performance is achieved by shading corrected CBCT and both deformable registration algorithms, with mean and standard deviation of dose metric error less than 1% for all sites studied. For lung images, use of deformed CT leads to slightly larger standard deviation of dose metric error than shading corrected CBCT with more dose metric errors greater than 2% observed (7% versus 1%).

A comparison of the Health Star Rating system when used for restaurant fast foods and packaged foods.

PubMed

Dunford, Elizabeth K; Wu, Jason H Y; Wellard-Cole, Lyndal; Watson, Wendy; Crino, Michelle; Petersen, Kristina; Neal, Bruce

2017-10-01

In June 2014, the Australian government agreed to the voluntary implementation of an interpretive 'Health Star Rating' (HSR) front-of-pack labelling system for packaged foods. The aim of the system is to make it easier for consumers to compare the healthiness of products based on number of stars. With many Australians consuming fast food there is a strong rationale for extending the HSR system to include fast food items. To examine the performance of the HSR system when applied to fast foods. Nutrient content data for fast food menu items were collected from the websites of 13 large Australian fast-food chains. The HSR was calculated for each menu item. Statistics describing HSR values for fast foods were calculated and compared to results for comparable packaged foods. Data for 1529 fast food products were compared to data for 3810 packaged food products across 16 of 17 fast food product categories. The mean HSR for the fast foods was 2.5 and ranged from 0.5 to 5.0 and corresponding values for the comparator packaged foods were 2.6 and 0.5 to 5.0. Visual inspection of the data showed broadly comparable distributions of HSR values across the fast food and the packaged food categories, although statistically significant differences were apparent for seven categories (all p < 0.04). In some cases these differences reflected the large sample size and the power to detect small variations across fast foods and packaged food, and in others it appeared to reflect primarily differences in the mix of product types within a category. These data support the idea that the HSR system could be extended to Australian fast foods. There are likely to be significant benefits to the community from the use of a single standardised signposting system for healthiness across all fresh, packaged and restaurant foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Administrative risk quantification of subcutaneous and intravenous therapies in Italian centers utilizing the Failure Mode and Effects Analysis approach.

PubMed

Ponzetti, Clemente; Canciani, Monica; Farina, Massimo; Era, Sara; Walzer, Stefan

2016-01-01

In oncology, an important parameter of safety is the potential treatment error in hospitals. The analyzed hypothesis is that of subcutaneous therapies would provide a superior safety benefit over intravenous therapies through fixed-dose administrations, when analyzed with trastuzumab and rituximab. For the calculation of risk levels, the Failure Mode and Effect Analysis approach was applied. Within this approach, the critical treatment path is followed and risk classification for each individual step is estimated. For oncology and hematology administration, 35 different risk steps were assessed. The study was executed in 17 hematology and 16 breast cancer centers in Italy. As intravenous and subcutaneous were the only injection routes in medical available for trastuzumab and rituximab in oncology at the time of the study, these two therapies were chosen. When the risk classes were calculated, eight high-risk areas were identified for the administration of an intravenous therapy in hematology or oncology; 13 areas would be defined as having a median-risk classification and 14 areas as having a low-risk classification (total risk areas: n=35). When the new subcutaneous formulation would be applied, 23 different risk levels could be completely eliminated (65% reduction). Important high-risk classes such as dose calculation, preparation and package labeling, preparation of the access to the vein, pump infusion preparation, and infusion monitoring were included in the eliminations. The overall risk level for the intravenous administration was estimated to be 756 (ex-ante) and could be reduced by 70% (ex-post). The potential harm compensation for errors related to pharmacy would be decreased from eight risk classes to only three risk classes. The subcutaneous administration of trastuzumab (breast cancer) and rituximab (hematology) might lower the risk of administration and treatment errors for patients and could hence indirectly have a positive financial impact for hospitals.

Alanine/EPR dosimetry applied to the verification of a total body irradiation protocol and treatment planning dose calculation using a humanoid phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeken, B.; Lelie, S.; Meijnders, P.

2010-12-15

Purpose: To avoid complications in total body irradiation (TBI), it is important to achieve a homogeneous dose distribution throughout the body and to deliver a correct dose to the lung which is an organ at risk. The purpose of this work was to validate the TBI dose protocol and to check the accuracy of the 3D dose calculations of the treatment planning system. Methods: Dosimetry based on alanine/electron paramagnetic resonance (EPR) was used to measure dose at numerous locations within an anthropomorphic phantom (Alderson) that was irradiated in a clinical TBI beam setup. The alanine EPR dosimetry system was calibratedmore » against water calorimetry in a Co-60 beam and the absorbed dose was determined by the use of ''dose-normalized amplitudes'' A{sub D}. The dose rate of the TBI beam was checked against a Farmer ionization chamber. The phantom measurements were compared to 3D dose calculations from a treatment planning system (Pinnacle) modeled for standard dose calculations. Results: Alanine dosimetry allowed accurate measurements which were in accordance with ionization chamber measurements. The combined relative standard measurement uncertainty in the Alderson phantom was U{sub r}(A{sub D})=0.6%. The humanoid phantom was irradiated to a reference dose of 10 Gy, limiting the lung dose to 7.5 Gy. The ratio of the average measured dose midplane in the craniocaudal direction to the reference dose was 1.001 with a spread of {+-}4.7% (1 sd). Dose to the lung was measured in 26 locations and found, in average, 1.8% lower than expected. Lung dose was homogeneous in the ventral-dorsal direction but a dose gradient of 0.10 Gy cm{sup -1} was observed in the craniocaudal direction midline within the lung lobe. 3D dose calculations (Pinnacle) were found, in average, 2% lower compared to dose measurements on the body axis and 3% lower for the lungs. Conclusions: The alanine/EPR dosimetry system allowed accurate dose measurements which enabled the authors to validate their TBI dose protocol. Dose calculations based on a collapsed cone convolution dose algorithm modeled for regular treatments are accurate within 3% and can further be improved when the algorithm is modeled for TBI.« less

Characterization of differences in calculated and actual measured skin doses to canine limbs during stereotactic radiosurgery using Gafchromic film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walters, Jerri; Colorado State University, Fort Collins, CO; Ryan, Stewart

Accurate calculation of absorbed dose to the skin, especially the superficial and radiosensitive basal cell layer, is difficult for many reasons including, but not limited to, the build-up effect of megavoltage photons, tangential beam effects, mixed energy scatter from support devices, and dose interpolation caused by a finite resolution calculation matrix. Stereotactic body radiotherapy (SBRT) has been developed as an alternative limb salvage treatment option at Colorado State University Veterinary Teaching Hospital for dogs with extremity bone tumors. Optimal dose delivery to the tumor during SBRT treatment can be limited by uncertainty in skin dose calculation. The aim of thismore » study was to characterize the difference between measured and calculated radiation dose by the Varian Eclipse (Varian Medical Systems, Palo Alto, CA) AAA treatment planning algorithm (for 1-mm, 2-mm, and 5-mm calculation voxel dimensions) as a function of distance from the skin surface. The study used Gafchromic EBT film (International Specialty Products, Wayne, NJ), FilmQA analysis software, a limb phantom constructed from plastic water Trade-Mark-Sign (fluke Biomedical, Everett, WA) and a canine cadaver forelimb. The limb phantom was exposed to 6-MV treatments consisting of a single-beam, a pair of parallel opposed beams, and a 7-beam coplanar treatment plan. The canine forelimb was exposed to the 7-beam coplanar plan. Radiation dose to the forelimb skin at the surface and at depths of 1.65 mm and 1.35 mm below the skin surface were also measured with the Gafchromic film. The calculation algorithm estimated the dose well at depths beyond buildup for all calculation voxel sizes. The calculation algorithm underestimated the dose in portions of the buildup region of tissue for all comparisons, with the most significant differences observed in the 5-mm calculation voxel and the least difference in the 1-mm voxel. Results indicate a significant difference between measured and calculated data extending to average depths of 2.5 mm, 3.4 mm, and 10 mm for the 1-mm, 2-mm, and 5-mm dimension calculation matrices, respectively. These results emphasize the importance of selecting as small a treatment planning software calculation matrix dimension as is practically possible and of taking a conservative approach for skin treatment planning objectives. One suggested conservative approach is accomplished by defining the skin organ as the outermost 2-3 mm of the body such that the high dose tail of the skin organ dose-volume histogram curve represents dose on the deep side of the skin where the algorithm is more accurate.« less

Recalculation of dose for each fraction of treatment on TomoTherapy.

PubMed

Thomas, Simon J; Romanchikova, Marina; Harrison, Karl; Parker, Michael A; Bates, Amy M; Scaife, Jessica E; Sutcliffe, Michael P F; Burnet, Neil G

2016-01-01

The VoxTox study, linking delivered dose to toxicity requires recalculation of typically 20-37 fractions per patient, for nearly 2000 patients. This requires a non-interactive interface permitting batch calculation with multiple computers. Data are extracted from the TomoTherapy(®) archive and processed using the computational task-management system GANGA. Doses are calculated for each fraction of radiotherapy using the daily megavoltage (MV) CT images. The calculated dose cube is saved as a digital imaging and communications in medicine RTDOSE object, which can then be read by utilities that calculate dose-volume histograms or dose surface maps. The rectum is delineated on daily MV images using an implementation of the Chan-Vese algorithm. On a cluster of up to 117 central processing units, dose cubes for all fractions of 151 patients took 12 days to calculate. Outlining the rectum on all slices and fractions on 151 patients took 7 h. We also present results of the Hounsfield unit (HU) calibration of TomoTherapy MV images, measured over an 8-year period, showing that the HU calibration has become less variable over time, with no large changes observed after 2011. We have developed a system for automatic dose recalculation of TomoTherapy dose distributions. This does not tie up the clinically needed planning system but can be run on a cluster of independent machines, enabling recalculation of delivered dose without user intervention. The use of a task management system for automation of dose calculation and outlining enables work to be scaled up to the level required for large studies.

Lens of the eye dose calculation for neuro-interventional procedures and CBCT scans of the head

NASA Astrophysics Data System (ADS)

Xiong, Zhenyu; Vijayan, Sarath; Rana, Vijay; Jain, Amit; Rudin, Stephen; Bednarek, Daniel R.

2016-03-01

The aim of this work is to develop a method to calculate lens dose for fluoroscopically-guided neuro-interventional procedures and for CBCT scans of the head. EGSnrc Monte Carlo software is used to determine the dose to the lens of the eye for the projection geometry and exposure parameters used in these procedures. This information is provided by a digital CAN bus on the Toshiba Infinix C-Arm system which is saved in a log file by the real-time skin-dose tracking system (DTS) we previously developed. The x-ray beam spectra on this machine were simulated using BEAMnrc. These spectra were compared to those determined by SpekCalc and validated through measured percent-depth-dose (PDD) curves and half-value-layer (HVL) measurements. We simulated CBCT procedures in DOSXYZnrc for a CTDI head phantom and compared the surface dose distribution with that measured with Gafchromic film, and also for an SK150 head phantom and compared the lens dose with that measured with an ionization chamber. Both methods demonstrated good agreement. Organ dose calculated for a simulated neuro-interventional-procedure using DOSXYZnrc with the Zubal CT voxel phantom agreed within 10% with that calculated by PCXMC code for most organs. To calculate the lens dose in a neuro-interventional procedure, we developed a library of normalized lens dose values for different projection angles and kVp's. The total lens dose is then calculated by summing the values over all beam projections and can be included on the DTS report at the end of the procedure.

Poster - Thurs Eve-43: Verification of dose calculation with tissue inhomogeneity using MapCHECK.

PubMed

Korol, R; Chen, J; Mosalaei, H; Karnas, S

2008-07-01

MapCHECK (Sun Nuclear, Melbourne, FL) with 445 diode detectors has been used widely for routine IMRT quality assurance (QA) 1 . However, routine IMRT QA has not included the verification of inhomogeneity effects. The objective of this study is to use MapCHECK and a phantom to verify dose calculation and IMRT delivery with tissue inhomogeneity. A phantom with tissue inhomogeneities was placed on top of MapCHECK to measure the planar dose for an anterior beam with photon energy 6 MV or 18 MV. The phantom was composed of a 3.5 cm thick block of lung equivalent material and solid water arranged side by side with a 0.5 cm slab of solid water on the top of the phantom. The phantom setup including MapCHECK was CT scanned and imported into Pinnacle 8.0d for dose calculation. Absolute dose distributions were compared with gamma criteria 3% for dose difference and 3 mm for distance-to-agreement. The results are in good agreement between the measured and calculated planar dose with 88% pass rate based on the gamma analysis. The major dose difference was at the lung-water interface. Further investigation will be performed on a custom designed inhomogeneity phantom with inserts of varying densities and effective depth to create various dose gradients at the interface for dose calculation and delivery verification. In conclusion, a phantom with tissue inhomogeneities can be used with MapCHECK for verification of dose calculation and delivery with tissue inhomogeneity. © 2008 American Association of Physicists in Medicine.

Shading correction for cone-beam CT in radiotherapy: validation of dose calculation accuracy using clinical images

NASA Astrophysics Data System (ADS)

Marchant, T. E.; Joshi, K. D.; Moore, C. J.

2017-03-01

Cone-beam CT (CBCT) images are routinely acquired to verify patient position in radiotherapy (RT), but are typically not calibrated in Hounsfield Units (HU) and feature non-uniformity due to X-ray scatter and detector persistence effects. This prevents direct use of CBCT for re-calculation of RT delivered dose. We previously developed a prior-image based correction method to restore HU values and improve uniformity of CBCT images. Here we validate the accuracy with which corrected CBCT can be used for dosimetric assessment of RT delivery, using CBCT images and RT plans for 45 patients including pelvis, lung and head sites. Dose distributions were calculated based on each patient's original RT plan and using CBCT image values for tissue heterogeneity correction. Clinically relevant dose metrics were calculated (e.g. median and minimum target dose, maximum organ at risk dose). Accuracy of CBCT based dose metrics was determined using an "override ratio" method where the ratio of the dose metric to that calculated on a bulk-density assigned version of the image is assumed to be constant for each patient, allowing comparison to "gold standard" CT. For pelvis and head images the proportion of dose errors >2% was reduced from 40% to 1.3% after applying shading correction. For lung images the proportion of dose errors >3% was reduced from 66% to 2.2%. Application of shading correction to CBCT images greatly improves their utility for dosimetric assessment of RT delivery, allowing high confidence that CBCT dose calculations are accurate within 2-3%.

Radiation Protection

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[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.

Permeability of model porous medium formed by random discs

NASA Astrophysics Data System (ADS)

Gubaidullin, A. A.; Gubkin, A. S.; Igoshin, D. E.; Ignatev, P. A.

2018-03-01

Two-dimension model of the porous medium with skeleton of randomly located overlapping discs is proposed. The geometry and computational grid are built in open package Salome. Flow of Newtonian liquid in longitudinal and transverse directions is calculated and its flow rate is defined. The numerical solution of the Navier-Stokes equations for a given pressure drop at the boundaries of the area is realized in the open package OpenFOAM. Calculated value of flow rate is used for defining of permeability coefficient on the base of Darcy law. For evaluating of representativeness of computational domain the permeability coefficients in longitudinal and transverse directions are compered.

Northwestern University Initiative for Teaching NanoSciences (NUITNS): An Approach for Teaching Computational Chemistry to Engineering Undergraduate Students

ERIC Educational Resources Information Center

Simeon, Tomekia; Aikens, Christine M.; Tejerina, Baudilio; Schatz, George C.

2011-01-01

The Northwestern University Initiative for Teaching Nanosciences (NUITNS) at nanohub.org Web site combines several tools for doing electronic structure calculations and analyzing and displaying the results into a coordinated package. In this article, we describe this package and show how it can be used as part of an upper-level quantum chemistry…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakowski, Cynthia L.; Guensch, Gregory R.; Patton, Gregory W.

Beginning in fiscal year 2003, the DOE Richland Operations Office initiated activities, including the development of data packages, to support the 2004 Composite Analysis. The river data package provides calculations of flow and transport in the Columbia River system. This document presents the data assembled to run the river module components for the section of the Columbia River from Vernita Bridge to the confluence with the Yakima River.

Quantiprot - a Python package for quantitative analysis of protein sequences.

PubMed

Konopka, Bogumił M; Marciniak, Marta; Dyrka, Witold

2017-07-17

The field of protein sequence analysis is dominated by tools rooted in substitution matrices and alignments. A complementary approach is provided by methods of quantitative characterization. A major advantage of the approach is that quantitative properties defines a multidimensional solution space, where sequences can be related to each other and differences can be meaningfully interpreted. Quantiprot is a software package in Python, which provides a simple and consistent interface to multiple methods for quantitative characterization of protein sequences. The package can be used to calculate dozens of characteristics directly from sequences or using physico-chemical properties of amino acids. Besides basic measures, Quantiprot performs quantitative analysis of recurrence and determinism in the sequence, calculates distribution of n-grams and computes the Zipf's law coefficient. We propose three main fields of application of the Quantiprot package. First, quantitative characteristics can be used in alignment-free similarity searches, and in clustering of large and/or divergent sequence sets. Second, a feature space defined by quantitative properties can be used in comparative studies of protein families and organisms. Third, the feature space can be used for evaluating generative models, where large number of sequences generated by the model can be compared to actually observed sequences.

Experimental evaluation of a GPU-based Monte Carlo dose calculation algorithm in the Monaco treatment planning system.

PubMed

Paudel, Moti R; Kim, Anthony; Sarfehnia, Arman; Ahmad, Sayed B; Beachey, David J; Sahgal, Arjun; Keller, Brian M

2016-11-08

A new GPU-based Monte Carlo dose calculation algorithm (GPUMCD), devel-oped by the vendor Elekta for the Monaco treatment planning system (TPS), is capable of modeling dose for both a standard linear accelerator and an Elekta MRI linear accelerator. We have experimentally evaluated this algorithm for a standard Elekta Agility linear accelerator. A beam model was developed in the Monaco TPS (research version 5.09.06) using the commissioned beam data for a 6 MV Agility linac. A heterogeneous phantom representing several scenarios - tumor-in-lung, lung, and bone-in-tissue - was designed and built. Dose calculations in Monaco were done using both the current clinical Monte Carlo algorithm, XVMC, and the new GPUMCD algorithm. Dose calculations in a Pinnacle TPS were also produced using the collapsed cone convolution (CCC) algorithm with heterogeneity correc-tion. Calculations were compared with the measured doses using an ionization chamber (A1SL) and Gafchromic EBT3 films for 2 × 2 cm2, 5 × 5 cm2, and 10 × 10 cm2 field sizes. The percentage depth doses (PDDs) calculated by XVMC and GPUMCD in a homogeneous solid water phantom were within 2%/2 mm of film measurements and within 1% of ion chamber measurements. For the tumor-in-lung phantom, the calculated doses were within 2.5%/2.5 mm of film measurements for GPUMCD. For the lung phantom, doses calculated by all of the algorithms were within 3%/3 mm of film measurements, except for the 2 × 2 cm2 field size where the CCC algorithm underestimated the depth dose by ~ 5% in a larger extent of the lung region. For the bone phantom, all of the algorithms were equivalent and calculated dose to within 2%/2 mm of film measurements, except at the interfaces. Both GPUMCD and XVMC showed interface effects, which were more pronounced for GPUMCD and were comparable to film measurements, whereas the CCC algorithm showed these effects poorly. © 2016 The Authors.

Radial secondary electron dose profiles and biological effects in light-ion beams based on analytical and Monte Carlo calculations using distorted wave cross sections.

PubMed

Wiklund, Kristin; Olivera, Gustavo H; Brahme, Anders; Lind, Bengt K

2008-07-01

To speed up dose calculation, an analytical pencil-beam method has been developed to calculate the mean radial dose distributions due to secondary electrons that are set in motion by light ions in water. For comparison, radial dose profiles calculated using a Monte Carlo technique have also been determined. An accurate comparison of the resulting radial dose profiles of the Bragg peak for (1)H(+), (4)He(2+) and (6)Li(3+) ions has been performed. The double differential cross sections for secondary electron production were calculated using the continuous distorted wave-eikonal initial state method (CDW-EIS). For the secondary electrons that are generated, the radial dose distribution for the analytical case is based on the generalized Gaussian pencil-beam method and the central axis depth-dose distributions are calculated using the Monte Carlo code PENELOPE. In the Monte Carlo case, the PENELOPE code was used to calculate the whole radial dose profile based on CDW data. The present pencil-beam and Monte Carlo calculations agree well at all radii. A radial dose profile that is shallower at small radii and steeper at large radii than the conventional 1/r(2) is clearly seen with both the Monte Carlo and pencil-beam methods. As expected, since the projectile velocities are the same, the dose profiles of Bragg-peak ions of 0.5 MeV (1)H(+), 2 MeV (4)He(2+) and 3 MeV (6)Li(3+) are almost the same, with about 30% more delta electrons in the sub keV range from (4)He(2+)and (6)Li(3+) compared to (1)H(+). A similar behavior is also seen for 1 MeV (1)H(+), 4 MeV (4)He(2+) and 6 MeV (6)Li(3+), all classically expected to have the same secondary electron cross sections. The results are promising and indicate a fast and accurate way of calculating the mean radial dose profile.

SU-F-P-19: Fetal Dose Estimate for a High-Dose Fluoroscopy Guided Intervention Using Modern Data Tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moirano, J

Purpose: An accurate dose estimate is necessary for effective patient management after a fetal exposure. In the case of a high-dose exposure, it is critical to use all resources available in order to make the most accurate assessment of the fetal dose. This work will demonstrate a methodology for accurate fetal dose estimation using tools that have recently become available in many clinics, and show examples of best practices for collecting data and performing the fetal dose calculation. Methods: A fetal dose estimate calculation was performed using modern data collection tools to determine parameters for the calculation. The reference pointmore » air kerma as displayed by the fluoroscopic system was checked for accuracy. A cumulative dose incidence map and DICOM header mining were used to determine the displayed reference point air kerma. Corrections for attenuation caused by the patient table and pad were measured and applied in order to determine the peak skin dose. The position and depth of the fetus was determined by ultrasound imaging and consultation with a radiologist. The data collected was used to determine a normalized uterus dose from Monte Carlo simulation data. Fetal dose values from this process were compared to other accepted calculation methods. Results: An accurate high-dose fetal dose estimate was made. Comparison to accepted legacy methods were were within 35% of estimated values. Conclusion: Modern data collection and reporting methods ease the process for estimation of fetal dose from interventional fluoroscopy exposures. Many aspects of the calculation can now be quantified rather than estimated, which should allow for a more accurate estimation of fetal dose.« less

A new shielding calculation method for X-ray computed tomography regarding scattered radiation.

PubMed

Watanabe, Hiroshi; Noto, Kimiya; Shohji, Tomokazu; Ogawa, Yasuyoshi; Fujibuchi, Toshioh; Yamaguchi, Ichiro; Hiraki, Hitoshi; Kida, Tetsuo; Sasanuma, Kazutoshi; Katsunuma, Yasushi; Nakano, Takurou; Horitsugi, Genki; Hosono, Makoto

2017-06-01

The goal of this study is to develop a more appropriate shielding calculation method for computed tomography (CT) in comparison with the Japanese conventional (JC) method and the National Council on Radiation Protection and Measurements (NCRP)-dose length product (DLP) method. Scattered dose distributions were measured in a CT room with 18 scanners (16 scanners in the case of the JC method) for one week during routine clinical use. The radiation doses were calculated for the same period using the JC and NCRP-DLP methods. The mean (NCRP-DLP-calculated dose)/(measured dose) ratios in each direction ranged from 1.7 ± 0.6 to 55 ± 24 (mean ± standard deviation). The NCRP-DLP method underestimated the dose at 3.4% in fewer shielding directions without the gantry and a subject, and the minimum (NCRP-DLP-calculated dose)/(measured dose) ratio was 0.6. The reduction factors were 0.036 ± 0.014 and 0.24 ± 0.061 for the gantry and couch directions, respectively. The (JC-calculated dose)/(measured dose) ratios ranged from 11 ± 8.7 to 404 ± 340. The air kerma scatter factor κ is expected to be twice as high as that calculated with the NCRP-DLP method and the reduction factors are expected to be 0.1 and 0.4 for the gantry and couch directions, respectively. We, therefore, propose a more appropriate method, the Japanese-DLP method, which resolves the issues of possible underestimation of the scattered radiation and overestimation of the reduction factors in the gantry and couch directions.

External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting.

PubMed

Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

2013-01-01

For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13.

External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting

PubMed Central

Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

2013-01-01

For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13. PMID:23542764

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system.

PubMed

Rana, V K; Rudin, S; Bednarek, D R

2016-09-01

Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries.

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

PubMed Central

Rana, V. K.; Rudin, S.; Bednarek, D. R.

2016-01-01

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. Conclusions: The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries. PMID:27587043

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, V. K., E-mail: vkrana@buffalo.edu

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, amore » data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. Conclusions: The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norris, Edward T.; Liu, Xin, E-mail: xinliu@mst.edu; Hsieh, Jiang

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. Themore » 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. Conclusions: The simulation results showed that the deterministic method can be effectively used to estimate the absorbed dose in a CTDI phantom. The accuracy of the discrete ordinates method was close to that of a Monte Carlo simulation, and the primary benefit of the discrete ordinates method lies in its rapid computation speed. It is expected that further optimization of this method in routine clinical CT dose estimation will improve its accuracy and speed.« less

Browns Ferry Nuclear Plant radiological impact assessment report, January-June 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, B.E.

1988-01-01

Potential doses to maximum individuals and the population around Browns Ferry are calcuated for each quarter. Measured plant releases for the reporting period are used to estimate these doses. Dispersion of radioactive effluents in the environment is estimated in accordance with the guidance provided and measuring during the period. Using dose calculation methodologies which are described in detail in the Browns Ferry Offsite Dose Calculation Manual, the doses are calculated and used to determine compliance with the dose limits contained in Browns Ferry's Operating License. In this report, the doses resulting from releases are described and compared to quarterly andmore » annual limits established for Browns Ferry.« less

Fast 3D dosimetric verifications based on an electronic portal imaging device using a GPU calculation engine.

PubMed

Zhu, Jinhan; Chen, Lixin; Chen, Along; Luo, Guangwen; Deng, Xiaowu; Liu, Xiaowei

2015-04-11

To use a graphic processing unit (GPU) calculation engine to implement a fast 3D pre-treatment dosimetric verification procedure based on an electronic portal imaging device (EPID). The GPU algorithm includes the deconvolution and convolution method for the fluence-map calculations, the collapsed-cone convolution/superposition (CCCS) algorithm for the 3D dose calculations and the 3D gamma evaluation calculations. The results of the GPU-based CCCS algorithm were compared to those of Monte Carlo simulations. The planned and EPID-based reconstructed dose distributions in overridden-to-water phantoms and the original patients were compared for 6 MV and 10 MV photon beams in intensity-modulated radiation therapy (IMRT) treatment plans based on dose differences and gamma analysis. The total single-field dose computation time was less than 8 s, and the gamma evaluation for a 0.1-cm grid resolution was completed in approximately 1 s. The results of the GPU-based CCCS algorithm exhibited good agreement with those of the Monte Carlo simulations. The gamma analysis indicated good agreement between the planned and reconstructed dose distributions for the treatment plans. For the target volume, the differences in the mean dose were less than 1.8%, and the differences in the maximum dose were less than 2.5%. For the critical organs, minor differences were observed between the reconstructed and planned doses. The GPU calculation engine was used to boost the speed of 3D dose and gamma evaluation calculations, thus offering the possibility of true real-time 3D dosimetric verification.

SU-E-T-423: Fast Photon Convolution Calculation with a 3D-Ideal Kernel On the GPU

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moriya, S; Sato, M; Tachibana, H

Purpose: The calculation time is a trade-off for improving the accuracy of convolution dose calculation with fine calculation spacing of the KERMA kernel. We investigated to accelerate the convolution calculation using an ideal kernel on the Graphic Processing Units (GPU). Methods: The calculation was performed on the AMD graphics hardware of Dual FirePro D700 and our algorithm was implemented using the Aparapi that convert Java bytecode to OpenCL. The process of dose calculation was separated with the TERMA and KERMA steps. The dose deposited at the coordinate (x, y, z) was determined in the process. In the dose calculation runningmore » on the central processing unit (CPU) of Intel Xeon E5, the calculation loops were performed for all calculation points. On the GPU computation, all of the calculation processes for the points were sent to the GPU and the multi-thread computation was done. In this study, the dose calculation was performed in a water equivalent homogeneous phantom with 150{sup 3} voxels (2 mm calculation grid) and the calculation speed on the GPU to that on the CPU and the accuracy of PDD were compared. Results: The calculation time for the GPU and the CPU were 3.3 sec and 4.4 hour, respectively. The calculation speed for the GPU was 4800 times faster than that for the CPU. The PDD curve for the GPU was perfectly matched to that for the CPU. Conclusion: The convolution calculation with the ideal kernel on the GPU was clinically acceptable for time and may be more accurate in an inhomogeneous region. Intensity modulated arc therapy needs dose calculations for different gantry angles at many control points. Thus, it would be more practical that the kernel uses a coarse spacing technique if the calculation is faster while keeping the similar accuracy to a current treatment planning system.« less

Evaluation of material heterogeneity dosimetric effects using radiochromic film for COMS eye plaques loaded with {sup 125}I seeds (model I25.S16)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acar, Hilal; Chiu-Tsao, Sou-Tung; Oezbay, Ismail

Purpose: (1) To measure absolute dose distributions in eye phantom for COMS eye plaques with {sup 125}I seeds (model I25.S16) using radiochromic EBT film dosimetry. (2) To determine the dose correction function for calculations involving the TG-43 formalism to account for the presence of the COMS eye plaque using Monte Carlo (MC) method specific to this seed model. (3) To test the heterogeneous dose calculation accuracy of the new version of Plaque Simulator (v5.3.9) against the EBT film data for this seed model. Methods: Using EBT film, absolute doses were measured for {sup 125}I seeds (model I25.S16) in COMS eyemore » plaques (1) along the plaque's central axis for (a) uniformly loaded plaques (14-20 mm in diameter) and (b) a 20 mm plaque with single seed, and (2) in off-axis direction at depths of 5 and 12 mm for all four plaque sizes. The EBT film calibration was performed at {sup 125}I photon energy. MC calculations using MCNP5 code for a single seed at the center of a 20 mm plaque in homogeneous water and polystyrene medium were performed. The heterogeneity dose correction function was determined from the MC calculations. These function values at various depths were entered into PS software (v5.3.9) to calculate the heterogeneous dose distributions for the uniformly loaded plaques (of all four sizes). The dose distributions with homogeneous water assumptions were also calculated using PS for comparison. The EBT film measured absolute dose rate values (film) were compared with those calculated using PS with homogeneous assumption (PS Homo) and heterogeneity correction (PS Hetero). The values of dose ratio (film/PS Homo) and (film/PS Hetero) were obtained. Results: The central axis depth dose rate values for a single seed in 20 mm plaque measured using EBT film and calculated with MCNP5 code (both in ploystyrene phantom) were compared, and agreement within 9% was found. The dose ratio (film/PS Homo) values were substantially lower than unity (mostly between 0.8 and 0.9) for all four plaque sizes, indicating dose reduction by COMS plaque compared with homogeneous assumption. The dose ratio (film/PS Hetero) values were close to unity, indicating the PS Hetero calculations agree with those from the film study. Conclusions: Substantial heterogeneity effect on the {sup 125}I dose distributions in an eye phantom for COMS plaques was verified using radiochromic EBT film dosimetry. The calculated doses for uniformly loaded plaques using PS with heterogeneity correction option enabled were corroborated by the EBT film measurement data. Radiochromic EBT film dosimetry is feasible in measuring absolute dose distributions in eye phantom for COMS eye plaques loaded with single or multiple {sup 125}I seeds. Plaque Simulator is a viable tool for the calculation of dose distributions if one understands its limitations and uses the proper heterogeneity correction feature.« less

Comparison of calculated beta- and gamma-ray doses after the Fukushima accident with data from single-grain luminescence retrospective dosimetry of quartz inclusions in a brick sample

PubMed Central

Endo, Satoru; Fujii, Keisuke; Kajimoto, Tsuyoshi; Tanaka, Kenichi; Stepanenko, Valeriy; Kolyzhenkov, Timofey; Petukhov, Aleksey; Akhmedova, Umukusum; Bogacheva, Viktoriia

2018-01-01

Abstract To estimate the beta- and gamma-ray doses in a brick sample taken from Odaka, Minami-Soma City, Fukushima Prefecture, Japan, a Monte Carlo calculation was performed with Particle and Heavy Ion Transport code System (PHITS) code. The calculated results were compared with data obtained by single-grain retrospective luminescence dosimetry of quartz inclusions in the brick sample. The calculated result agreed well with the measured data. The dose increase measured at the brick surface was explained by the beta-ray contribution, and the slight slope in the dose profile deeper in the brick was due to the gamma-ray contribution. The skin dose was estimated from the calculated result as 164 mGy over 3 years at the sampling site. PMID:29385528

Comparison of calculated beta- and gamma-ray doses after the Fukushima accident with data from single-grain luminescence retrospective dosimetry of quartz inclusions in a brick sample.

PubMed

Endo, Satoru; Fujii, Keisuke; Kajimoto, Tsuyoshi; Tanaka, Kenichi; Stepanenko, Valeriy; Kolyzhenkov, Timofey; Petukhov, Aleksey; Akhmedova, Umukusum; Bogacheva, Viktoriia

2018-05-01

To estimate the beta- and gamma-ray doses in a brick sample taken from Odaka, Minami-Soma City, Fukushima Prefecture, Japan, a Monte Carlo calculation was performed with Particle and Heavy Ion Transport code System (PHITS) code. The calculated results were compared with data obtained by single-grain retrospective luminescence dosimetry of quartz inclusions in the brick sample. The calculated result agreed well with the measured data. The dose increase measured at the brick surface was explained by the beta-ray contribution, and the slight slope in the dose profile deeper in the brick was due to the gamma-ray contribution. The skin dose was estimated from the calculated result as 164 mGy over 3 years at the sampling site.

Impact of grid size on uniform scanning and IMPT plans in XiO treatment planning system for brain cancer

PubMed Central

Zheng, Yuanshui

2015-01-01

The main purposes of this study are to: 1) evaluate the accuracy of XiO treatment planning system (TPS) for different dose calculation grid size based on head phantom measurements in uniform scanning proton therapy (USPT); and 2) compare the dosimetric results for various dose calculation grid sizes based on real computed tomography (CT) dataset of pediatric brain cancer treatment plans generated by USPT and intensity‐modulated proton therapy (IMPT) techniques. For phantom study, we have utilized the anthropomorphic head proton phantom provided by Imaging and Radiation Oncology Core (IROC). The imaging, treatment planning, and beam delivery were carried out following the guidelines provided by the IROC. The USPT proton plan was generated in the XiO TPS, and dose calculations were performed for grid size ranged from 1 to 3 mm. The phantom containing thermoluminescent dosimeter (TLDs) and films was irradiated using uniform scanning proton beam. The irradiated TLDs were read by the IROC. The calculated doses from the XiO for different grid sizes were compared to the measured TLD doses provided by the IROC. Gamma evaluation was done by comparing calculated planar dose distribution of 3 mm grid size with measured planar dose distribution. Additionally, IMPT plan was generated based on the same CT dataset of the IROC phantom, and IMPT dose calculations were performed for grid size ranged from 1 to 3 mm. For comparative purpose, additional gamma analysis was done by comparing the planar dose distributions of standard grid size (3 mm) with that of other grid sizes (1, 1.5, 2, and 2.5 mm) for both the USPT and IMPT plans. For patient study, USPT plans of three pediatric brain cancer cases were selected. IMPT plans were generated for each of three pediatric cases. All patient treatment plans (USPT and IMPT) were generated in the XiO TPS for a total dose of 54 Gy (relative biological effectiveness [RBE]). Treatment plans (USPT and IMPT) of each case was recalculated for grid sizes of 1, 1.5, 2, and 2.5 mm; these dosimetric results were then compared with that of 3 mm grid size. Phantom study results: There was no distinct trend exhibiting the dependence of grid size on dose calculation accuracy when calculated point dose of different grid sizes were compared to the measured point (TLD) doses. On average, the calculated point dose was higher than the measured dose by 1.49% and 2.63% for the right and left TLDs, respectively. The gamma analysis showed very minimal differences among planar dose distributions of various grid sizes, with percentage of points meeting gamma index criteria 1% and 1 mm to be from 97.92% to 99.97%. The gamma evaluation using 2% and 2 mm criteria showed both the IMPT and USPT plans have 100% points meeting the criteria. Patient study results: In USPT, there was no very distinct relationship between the absolute difference in mean planning target volume (PTV) dose and grid size, whereas in IMPT, it was found that the decrease in grid size slightly increased the PTV maximum dose and decreased the PTV mean dose and PTV D50%. For the PTV doses, the average differences were up to 0.35 Gy (RBE) and 1.47 Gy (RBE) in the USPT and IMPT plans, respectively. Dependency on grid size was not very clear for the organs at risk (OARs), with average difference ranged from −0.61 Gy (RBE) to 0.53 Gy (RBE) in the USPT plans and from −0.83 Gy (RBE) to 1.39 Gy (RBE) in the IMPT plans. In conclusion, the difference in the calculated point dose between the smallest grid size (1 mm) and the largest grid size (3 mm) in phantom for USPT was typically less than 0.1%. Patient study results showed that the decrease in grid size slightly increased the PTV maximum dose in both the USPT and IMPT plans. However, no distinct trend was obtained between the absolute difference in dosimetric parameter and dose calculation grid size for the OARs. Grid size has a large effect on dose calculation efficiency, and use of 2 mm or less grid size can increase the dose calculation time significantly. It is recommended to use grid size either 2.5 or 3 mm for dose calculations of pediatric brain cancer plans generated by USPT and IMPT techniques in XiO TPS. PACS numbers: 87.55.D‐, 87.55.ne, 87.55.dk PMID:26699310

gkmSVM: an R package for gapped-kmer SVM.

PubMed

Ghandi, Mahmoud; Mohammad-Noori, Morteza; Ghareghani, Narges; Lee, Dongwon; Garraway, Levi; Beer, Michael A

2016-07-15

We present a new R package for training gapped-kmer SVM classifiers for DNA and protein sequences. We describe an improved algorithm for kernel matrix calculation that speeds run time by about 2 to 5-fold over our original gkmSVM algorithm. This package supports several sequence kernels, including: gkmSVM, kmer-SVM, mismatch kernel and wildcard kernel. gkmSVM package is freely available through the Comprehensive R Archive Network (CRAN), for Linux, Mac OS and Windows platforms. The C ++ implementation is available at www.beerlab.org/gkmsvm mghandi@gmail.com or mbeer@jhu.edu Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Solution of the Schrodinger Equation for One-Dimensional Anharmonic Potentials: An Undergraduate Computational Experiment

ERIC Educational Resources Information Center

Beddard, Godfrey S.

2011-01-01

A method of solving the Schrodinger equation using a basis set expansion is described and used to calculate energy levels and wavefunctions of the hindered rotation of ethane and the ring puckering of cyclopentene. The calculations were performed using a computer algebra package and the calculations are straightforward enough for undergraduates to…

Effect of Addition of Natural Antioxidants on the Shelf-Life of “Chorizo”, a Spanish Dry-Cured Sausage

PubMed Central

Pateiro, Mirian; Bermúdez, Roberto; Lorenzo, José Manuel; Franco, Daniel

2015-01-01

The dose effect of the addition of natural antioxidants (tea, chestnut, grape seed and beer extracts) on physicochemical, microbiological changes and on oxidative stability of dry-cured “chorizo”, as well as their effect during the storage under vacuum conditions was evaluated. Color parameters were significantly (p < 0.05) affected by the addition of antioxidants so that samples that contained antioxidants were more effective in maintaining color. The improving effects were dose-dependent with highest values with the dose of 50 mg/kg during ripening and depend on the extract during vacuum packaging. Addition of antioxidants decreased (p < 0.05) the oxidation, showing thiobarbituric acid reactive substances (TBARS) values below 0.4 mg MDA/kg. Natural antioxidants matched or even improved the results obtained for butylated hydroxytoluene (BHT). Regarding texture profile analysis (TPA) analysis, hardness values significantly (p < 0.001) decreased with the addition of antioxidants, obtaining the lower results with the dose of 200 mg/kg both during ripening and vacuum packaging. Antioxidants reduced the counts of total viable counts (TVC), lactic acid bacteria (LAB), mold and yeast. Free fatty acid content during ripening and under vacuum conditions showed a gradual and significant (p < 0.05) release as a result of lipolysis. At the end of ripening, the addition of GRA1000 protected chorizos from oxidative degradation. PMID:26785337

Estimating Likelihood of Fetal In Vivo Interactions Using In ...

EPA Pesticide Factsheets

Tox21/ToxCast efforts provide in vitro concentration-response data for thousands of compounds. Predicting whether chemical-biological interactions observed in vitro will occur in vivo is challenging. We hypothesize that using a modified model from the FDA guidance for drug interaction studies, Cmax/AC50 (i.e., maximal in vivo blood concentration over the half-maximal in in vitro activity concentration), will give a useful approximation for concentrations where in vivo interactions are likely. Further, for doses where maternal blood concentrations are likely to elicit an interaction (Cmax/AC50>0.1), where do the compounds accumulate in fetal tissues? In order to estimate these doses based on Tox21 data, in silico parameters of chemical fraction unbound in plasma and intrinsic hepatic clearance were estimated from ADMET predictor (Simulations-Plus Inc.) and used in the HTTK R-package to obtain Cmax values from a physiologically-based toxicokinetics model. In silico estimated Cmax values predicted in vivo human Cmax with median absolute error of 0.81 for 93 chemicals, giving confidence in the R-package and in silico estimates. A case example evaluating Cmax/AC50 values for peroxisome proliferator-activated receptor gamma (PPARγ) and glucocorticoid receptor revealed known compounds (glitazones and corticosteroids, respectively) highest on the list at pharmacological doses. Doses required to elicit likely interactions across all Tox21/ToxCast assays were compared to

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cebe, M; Pacaci, P; Mabhouti, H

Purpose: In this study, the two available calculation algorithms of the Varian Eclipse treatment planning system(TPS), the electron Monte Carlo(eMC) and General Gaussian Pencil Beam(GGPB) algorithms were used to compare measured and calculated peripheral dose distribution of electron beams. Methods: Peripheral dose measurements were carried out for 6, 9, 12, 15, 18 and 22 MeV electron beams of Varian Triology machine using parallel plate ionization chamber and EBT3 films in the slab phantom. Measurements were performed for 6×6, 10×10 and 25×25cm{sup 2} cone sizes at dmax of each energy up to 20cm beyond the field edges. Using the same filmmore » batch, the net OD to dose calibration curve was obtained for each energy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution measured using parallel plate ionization chamber and EBT3 film and calculated by eMC and GGPB algorithms were compared. The measured and calculated data were then compared to find which algorithm calculates peripheral dose distribution more accurately. Results: The agreement between measurement and eMC was better than GGPB. The TPS underestimated the out of field doses. The difference between measured and calculated doses increase with the cone size. The largest deviation between calculated and parallel plate ionization chamber measured dose is less than 4.93% for eMC, but it can increase up to 7.51% for GGPB. For film measurement, the minimum gamma analysis passing rates between measured and calculated dose distributions were 98.2% and 92.7% for eMC and GGPB respectively for all field sizes and energies. Conclusion: Our results show that the Monte Carlo algorithm for electron planning in Eclipse is more accurate than previous algorithms for peripheral dose distributions. It must be emphasized that the use of GGPB for planning large field treatments with 6 MeV could lead to inaccuracies of clinical significance.« less

Optimization of Monte Carlo dose calculations: The interface problem

NASA Astrophysics Data System (ADS)

Soudentas, Edward

1998-05-01

High energy photon beams are widely used for radiation treatment of deep-seated tumors. The human body contains many types of interfaces between dissimilar materials that affect dose distribution in radiation therapy. Experimentally, significant radiation dose perturbations has been observed at such interfaces. The EGS4 Monte Carlo code was used to calculate dose perturbations at boundaries between dissimilar materials (such as bone/water) for 60Co and 6 MeV linear accelerator beams using a UNIX workstation. A simple test of the reliability of a random number generator was also developed. A systematic study of the adjustable parameters in EGS4 was performed in order to minimize calculational artifacts at boundaries. Calculations of dose perturbations at boundaries between different materials showed that there is a 12% increase in dose at water/bone interface, and a 44% increase in dose at water/copper interface. with the increase mainly due to electrons produced in water and backscattered from the high atomic number material. The dependence of the dose increase on the atomic number was also investigated. The clinically important case of using two parallel opposed beams for radiation therapy was investigated where increased doses at boundaries has been observed. The Monte Carlo calculations can provide accurate dosimetry data under conditions of electronic non-equilibrium at tissue interfaces.

Estimation of median human lethal radiation dose computed from data on occupants of reinforced concrete structures in Nagasaki, Japan.

PubMed

Levin, S G; Young, R W; Stohler, R L

1992-11-01

This paper presents an estimate of the median lethal dose for humans exposed to total-body irradiation and not subsequently treated for radiation sickness. The median lethal dose was estimated from calculated doses to young adults who were inside two reinforced concrete buildings that remained standing in Nagasaki after the atomic detonation. The individuals in this study, none of whom have previously had calculated doses, were identified from a detailed survey done previously. Radiation dose to the bone marrow, which was taken as the critical radiation site, was calculated for each individual by the Engineering Physics and Mathematics Division of the Oak Ridge National Laboratory using a new three-dimensional discrete-ordinates radiation transport code that was developed and validated for this study using the latest site geometry, radiation yield, and spectra data. The study cohort consisted of 75 individuals who either survived > 60 d or died between the second and 60th d postirradiation due to radiation injury, without burns or other serious injury. Median lethal dose estimates were calculated using both logarithmic (2.9 Gy) and linear (3.4 Gy) dose scales. Both calculations, which met statistical validity tests, support previous estimates of the median lethal dose based solely on human data, which cluster around 3 Gy.

Biphasic and monophasic repair: comparative implications for biologically equivalent dose calculations in pulsed dose rate brachytherapy of cervical carcinoma

PubMed Central

Millar, W T; Davidson, S E

2013-01-01

Objective: To consider the implications of the use of biphasic rather than monophasic repair in calculations of biologically-equivalent doses for pulsed-dose-rate brachytherapy of cervix carcinoma. Methods: Calculations are presented of pulsed-dose-rate (PDR) doses equivalent to former low-dose-rate (LDR) doses, using biphasic vs monophasic repair kinetics, both for cervical carcinoma and for the organ at risk (OAR), namely the rectum. The linear-quadratic modelling calculations included effects due to varying the dose per PDR cycle, the dose reduction factor for the OAR compared with Point A, the repair kinetics and the source strength. Results: When using the recommended 1 Gy per hourly PDR cycle, different LDR-equivalent PDR rectal doses were calculated depending on the choice of monophasic or biphasic repair kinetics pertaining to the rodent central nervous and skin systems. These differences virtually disappeared when the dose per hourly cycle was increased to 1.7 Gy. This made the LDR-equivalent PDR doses more robust and independent of the choice of repair kinetics and α/β ratios as a consequence of the described concept of extended equivalence. Conclusion: The use of biphasic and monophasic repair kinetics for optimised modelling of the effects on the OAR in PDR brachytherapy suggests that an optimised PDR protocol with the dose per hourly cycle nearest to 1.7 Gy could be used. Hence, the durations of the new PDR treatments would be similar to those of the former LDR treatments and not longer as currently prescribed. Advances in knowledge: Modelling calculations indicate that equivalent PDR protocols can be developed which are less dependent on the different α/β ratios and monophasic/biphasic kinetics usually attributed to normal and tumour tissues for treatment of cervical carcinoma. PMID:23934965

Dosimetric comparison of helical tomotherapy treatment plans for total marrow irradiation created using GPU and CPU dose calculation engines.

PubMed

Nalichowski, Adrian; Burmeister, Jay

2013-07-01

To compare optimization characteristics, plan quality, and treatment delivery efficiency between total marrow irradiation (TMI) plans using the new TomoTherapy graphic processing unit (GPU) based dose engine and CPU/cluster based dose engine. Five TMI plans created on an anthropomorphic phantom were optimized and calculated with both dose engines. The planning treatment volume (PTV) included all the bones from head to mid femur except for upper extremities. Evaluated organs at risk (OAR) consisted of lung, liver, heart, kidneys, and brain. The following treatment parameters were used to generate the TMI plans: field widths of 2.5 and 5 cm, modulation factors of 2 and 2.5, and pitch of either 0.287 or 0.43. The optimization parameters were chosen based on the PTV and OAR priorities and the plans were optimized with a fixed number of iterations. The PTV constraint was selected to ensure that at least 95% of the PTV received the prescription dose. The plans were evaluated based on D80 and D50 (dose to 80% and 50% of the OAR volume, respectively) and hotspot volumes within the PTVs. Gamma indices (Γ) were also used to compare planar dose distributions between the two modalities. The optimization and dose calculation times were compared between the two systems. The treatment delivery times were also evaluated. The results showed very good dosimetric agreement between the GPU and CPU calculated plans for any of the evaluated planning parameters indicating that both systems converge on nearly identical plans. All D80 and D50 parameters varied by less than 3% of the prescription dose with an average difference of 0.8%. A gamma analysis Γ(3%, 3 mm) < 1 of the GPU plan resulted in over 90% of calculated voxels satisfying Γ < 1 criterion as compared to baseline CPU plan. The average number of voxels meeting the Γ < 1 criterion for all the plans was 97%. In terms of dose optimization/calculation efficiency, there was a 20-fold reduction in planning time with the new GPU system. The average optimization/dose calculation time utilizing the traditional CPU/cluster based system was 579 vs 26.8 min for the GPU based system. There was no difference in the calculated treatment delivery time per fraction. Beam-on time varied based on field width and pitch and ranged between 15 and 28 min. The TomoTherapy GPU based dose engine is capable of calculating TMI treatment plans with plan quality nearly identical to plans calculated using the traditional CPU/cluster based system, while significantly reducing the time required for optimization and dose calculation.

Probablistic Analyses of Waste Package Quantities Impacted by Potential Igneous Disruption at Yucca Mountain

NASA Astrophysics Data System (ADS)

Wallace, M. G.; Iuzzolina, H.

2005-12-01

A probabilistic analysis was conducted to estimate ranges for the numbers of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analysis includes disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application for the Yucca Mountain Project (YMP). The first scenario, igneous intrusion, investigated the case where one or more igneous dikes intersect the repository. A swarm of dikes was characterized by distributions of length, width, azimuth, and number of dikes and the spacings between them. Through the use in part of a latin hypercube simulator and a modified video game engine, mathematical relationships were built between those parameters and the number of waste packages hit. Corresponding cumulative distribution function curves (CDFs) for the number of waste packages hit under several different scenarios were calculated. Variations in dike thickness ranges, as well as in repository magma bulkhead positions were examined through sensitivity studies. It was assumed that all waste packages in an emplacement drift would be impacted if that drift was intersected by a dike. Over 10,000 individual simulations were performed. Based on these calculations, out of a total of over 11,000 planned waste packages distributed over an area of approximately 5.5 km2 , the median number of waste packages impacted was roughly 1/10 of the total. Individual cases ranged from 0 waste packages to the entire inventory being impacted. The igneous intrusion analysis involved an explicit characterization of dike-drift intersections, built upon various distributions that reflect the uncertainties associated with the inputs. The second igneous scenario, volcanic eruption (eruptive conduits), considered the effects of conduits formed in association with a volcanic eruption through the repository. Mathematical relations were built between the resulting conduit areas and the fraction of the repository area occupied by waste packages. This relation was used in conjunction with a joint distribution incorporating variability in eruptive conduit diameters and in the number of eruptive conduits that could intersect the repository.

DESIGN ANALYSIS FOR THE DEFENSE HIGH-LEVEL WASTE DISPOSAL CONTAINER

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. Radulesscu; J.S. Tang

The purpose of ''Design Analysis for the Defense High-Level Waste Disposal Container'' analysis is to technically define the defense high-level waste (DHLW) disposal container/waste package using the Waste Package Department's (WPD) design methods, as documented in ''Waste Package Design Methodology Report'' (CRWMS M&O [Civilian Radioactive Waste Management System Management and Operating Contractor] 2000a). The DHLW disposal container is intended for disposal of commercial high-level waste (HLW) and DHLW (including immobilized plutonium waste forms), placed within disposable canisters. The U.S. Department of Energy (DOE)-managed spent nuclear fuel (SNF) in disposable canisters may also be placed in a DHLW disposal container alongmore » with HLW forms. The objective of this analysis is to demonstrate that the DHLW disposal container/waste package satisfies the project requirements, as embodied in Defense High Level Waste Disposal Container System Description Document (SDD) (CRWMS M&O 1999a), and additional criteria, as identified in Waste Package Design Sensitivity Report (CRWMS M&Q 2000b, Table 4). The analysis briefly describes the analytical methods appropriate for the design of the DHLW disposal contained waste package, and summarizes the results of the calculations that illustrate the analytical methods. However, the analysis is limited to the calculations selected for the DHLW disposal container in support of the Site Recommendation (SR) (CRWMS M&O 2000b, Section 7). The scope of this analysis is restricted to the design of the codisposal waste package of the Savannah River Site (SRS) DHLW glass canisters and the Training, Research, Isotopes General Atomics (TRIGA) SNF loaded in a short 18-in.-outer diameter (OD) DOE standardized SNF canister. This waste package is representative of the waste packages that consist of the DHLW disposal container, the DHLW/HLW glass canisters, and the DOE-managed SNF in disposable canisters. The intended use of this analysis is to support Site Recommendation reports and to assist in the development of WPD drawings. Activities described in this analysis were conducted in accordance with the Development Plan ''Design Analysis for the Defense High-Level Waste Disposal Container'' (CRWMS M&O 2000c) with no deviations from the plan.« less

Dose calculation with respiration-averaged CT processed from cine CT without a respiratory surrogate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riegel, Adam C.; Ahmad, Moiz; Sun Xiaojun

2008-12-15

Dose calculation for thoracic radiotherapy is commonly performed on a free-breathing helical CT despite artifacts caused by respiratory motion. Four-dimensional computed tomography (4D-CT) is one method to incorporate motion information into the treatment planning process. Some centers now use the respiration-averaged CT (RACT), the pixel-by-pixel average of the ten phases of 4D-CT, for dose calculation. This method, while sparing the tedious task of 4D dose calculation, still requires 4D-CT technology. The authors have recently developed a means to reconstruct RACT directly from unsorted cine CT data from which 4D-CT is formed, bypassing the need for a respiratory surrogate. Using RACTmore » from cine CT for dose calculation may be a means to incorporate motion information into dose calculation without performing 4D-CT. The purpose of this study was to determine if RACT from cine CT can be substituted for RACT from 4D-CT for the purposes of dose calculation, and if increasing the cine duration can decrease differences between the dose distributions. Cine CT data and corresponding 4D-CT simulations for 23 patients with at least two breathing cycles per cine duration were retrieved. RACT was generated four ways: First from ten phases of 4D-CT, second, from 1 breathing cycle of images, third, from 1.5 breathing cycles of images, and fourth, from 2 breathing cycles of images. The clinical treatment plan was transferred to each RACT and dose was recalculated. Dose planes were exported at orthogonal planes through the isocenter (coronal, sagittal, and transverse orientations). The resulting dose distributions were compared using the gamma ({gamma}) index within the planning target volume (PTV). Failure criteria were set to 2%/1 mm. A follow-up study with 50 additional lung cancer patients was performed to increase sample size. The same dose recalculation and analysis was performed. In the primary patient group, 22 of 23 patients had 100% of points within the PTV pass {gamma} criteria. The average maximum and mean {gamma} indices were very low (well below 1), indicating good agreement between dose distributions. Increasing the cine duration generally increased the dose agreement. In the follow-up study, 49 of 50 patients had 100% of points within the PTV pass the {gamma} criteria. The average maximum and mean {gamma} indices were again well below 1, indicating good agreement. Dose calculation on RACT from cine CT is negligibly different from dose calculation on RACT from 4D-CT. Differences can be decreased further by increasing the cine duration of the cine CT scan.« less

WE-FG-202-12: Investigation of Longitudinal Salivary Gland DCE-MRI Changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ger, R; Howell, R; Li, H

Purpose: To determine the correlation between dose and changes through treatment in dynamic contrast enhanced (DCE) MRI voxel parameters (Ktrans, kep, Ve, and Vp) within salivary glands of head and neck oropharyngeal squamous cell carcinoma (HNSCC) patients. Methods: 17 HNSCC patients treated with definitive radiation therapy completed DCE-MRI scans on a 3T scanner at pre-treatment, mid-treatment, and post-treatment time points. Mid-treatment and post-treatment DCE images were deformably registered to pre-treatment DCE images (Velocity software package). Pharmacokinetic analysis of the DCE images used a modified Tofts model to produce parameter maps with an arterial input function selected from each patient’s perivertebralmore » space on the image (NordicICE software package). In-house software was developed for voxel-by-voxel longitudinal analysis of the salivary glands within the registered images. The planning CT was rigidly registered to the pre-treatment DCE image to obtain dose values in each voxel. Voxels within the lower and upper dose quartiles for each gland were averaged for each patient, then an average of the patients’ means for the two quartiles were compared. Dose-relationships were also assessed by Spearman correlations between dose and voxel parameter changes for each patient’s gland. Results: Changes in parameters’ means between time points were observed, but inter-patient variability was high. Ve of the parotid was the only parameter that had a consistently significant longitudinal difference between dose quartiles. The highest Spearman correlation was Vp of the sublingual gland for the change in the pre-treatment to mid-treatment values with only a ρ=0.29. Conclusion: In this preliminary study, there was large inter-patient variability in the changes of DCE voxel parameters with no clear relationship with dose. Additional patients may reduce the uncertainties and allow for the determination of the existence of parameter and dose relationships.« less

WE-D-BRA-04: Online 3D EPID-Based Dose Verification for Optimum Patient Safety

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spreeuw, H; Rozendaal, R; Olaciregui-Ruiz, I

2015-06-15

Purpose: To develop an online 3D dose verification tool based on EPID transit dosimetry to ensure optimum patient safety in radiotherapy treatments. Methods: A new software package was developed which processes EPID portal images online using a back-projection algorithm for the 3D dose reconstruction. The package processes portal images faster than the acquisition rate of the portal imager (∼ 2.5 fps). After a portal image is acquired, the software seeks for “hot spots” in the reconstructed 3D dose distribution. A hot spot is in this study defined as a 4 cm{sup 3} cube where the average cumulative reconstructed dose exceedsmore » the average total planned dose by at least 20% and 50 cGy. If a hot spot is detected, an alert is generated resulting in a linac halt. The software has been tested by irradiating an Alderson phantom after introducing various types of serious delivery errors. Results: In our first experiment the Alderson phantom was irradiated with two arcs from a 6 MV VMAT H&N treatment having a large leaf position error or a large monitor unit error. For both arcs and both errors the linac was halted before dose delivery was completed. When no error was introduced, the linac was not halted. The complete processing of a single portal frame, including hot spot detection, takes about 220 ms on a dual hexacore Intel Xeon 25 X5650 CPU at 2.66 GHz. Conclusion: A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for various kinds of gross delivery errors. The detection of hot spots was proven to be effective for the timely detection of these errors. Current work is focused on hot spot detection criteria for various treatment sites and the introduction of a clinical pilot program with online verification of hypo-fractionated (lung) treatments.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 themore » 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.« less

Comparison of EGS4 and MCNP Monte Carlo codes when calculating radiotherapy depth doses.

PubMed

Love, P A; Lewis, D G; Al-Affan, I A; Smith, C W

1998-05-01

The Monte Carlo codes EGS4 and MCNP have been compared when calculating radiotherapy depth doses in water. The aims of the work were to study (i) the differences between calculated depth doses in water for a range of monoenergetic photon energies and (ii) the relative efficiency of the two codes for different electron transport energy cut-offs. The depth doses from the two codes agree with each other within the statistical uncertainties of the calculations (1-2%). The relative depth doses also agree with data tabulated in the British Journal of Radiology Supplement 25. A discrepancy in the dose build-up region may by attributed to the different electron transport algorithims used by EGS4 and MCNP. This discrepancy is considerably reduced when the improved electron transport routines are used in the latest (4B) version of MCNP. Timing calculations show that EGS4 is at least 50% faster than MCNP for the geometries used in the simulations.

WOLF: a computer code package for the calculation of ion beam trajectories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogel, D.L.

1985-10-01

The WOLF code solves POISSON'S equation within a user-defined problem boundary of arbitrary shape. The code is compatible with ANSI FORTRAN and uses a two-dimensional Cartesian coordinate geometry represented on a triangular lattice. The vacuum electric fields and equipotential lines are calculated for the input problem. The use may then introduce a series of emitters from which particles of different charge-to-mass ratios and initial energies can originate. These non-relativistic particles will then be traced by WOLF through the user-defined region. Effects of ion and electron space charge are included in the calculation. A subprogram PISA forms part of this codemore » and enables optimization of various aspects of the problem. The WOLF package also allows detailed graphics analysis of the computed results to be performed.« less

Online 3D EPID-based dose verification: Proof of concept

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spreeuw, Hanno; Rozendaal, Roel, E-mail: r.rozenda

Purpose: Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of thismore » study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. Methods: The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. Results: The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame, including dose verification, took 266 ± 11 ms on a dual octocore Intel Xeon E5-2630 CPU running at 2.40 GHz. The introduced delivery errors were detected after 5–10 s irradiation time. Conclusions: A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for two different kinds of gross delivery errors. Thus, online 3D dose verification has been technologically achieved.« less

Estimation of the influence of radical effect in the proton beams using a combined approach with physical data and gel data

NASA Astrophysics Data System (ADS)

Haneda, K.

2016-04-01

The purpose of this study was to estimate an impact on radical effect in the proton beams using a combined approach with physical data and gel data. The study used two dosimeters: ionization chambers and polymer gel dosimeters. Polymer gel dosimeters have specific advantages when compared to other dosimeters. They can measure chemical reaction and they are at the same time a phantom that can map in three dimensions continuously and easily. First, a depth-dose curve for a 210 MeV proton beam measured using an ionization chamber and a gel dosimeter. Second, the spatial distribution of the physical dose was calculated by Monte Carlo code system PHITS: To verify of the accuracy of Monte Carlo calculation, and the calculation results were compared with experimental data of the ionization chamber. Last, to evaluate of the rate of the radical effect against the physical dose. The simulation results were compared with the measured depth-dose distribution and showed good agreement. The spatial distribution of a gel dose with threshold LET value of proton beam was calculated by the same simulation code. Then, the relative distribution of the radical effect was calculated from the physical dose and gel dose. The relative distribution of the radical effect was calculated at each depth as the quotient of relative dose obtained using physical and gel dose. The agreement between the relative distributions of the gel dosimeter and Radical effect was good at the proton beams.

SU-G-206-17: RadShield: Semi-Automated Shielding Design for CT Using NCRP 147 and Isodose Curves

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeLorenzo, M; Rutel, I; Yang, K

2016-06-15

Purpose: Computed tomography (CT) exam rooms are shielded more quickly and accurately compared to manual calculations using RadShield, a semi-automated diagnostic shielding software package. Last year, we presented RadShield’s approach to shielding radiographic and fluoroscopic rooms calculating air kerma rate and barrier thickness at many points on the floor plan and reporting the maximum values for each barrier. RadShield has now been expanded to include CT shielding design using not only NCRP 147 methodology but also by overlaying vendor provided isodose curves onto the floor plan. Methods: The floor plan image is imported onto the RadShield workspace to serve asmore » a template for drawing barriers, occupied regions and CT locations. SubGUIs are used to set design goals, occupancy factors, workload, and overlay isodose curve files. CTDI and DLP methods are solved following NCRP 147. RadShield’s isodose curve method employs radial scanning to extract data point sets to fit kerma to a generalized power law equation of the form K(r) = ar^b. RadShield’s semiautomated shielding recommendations were compared against a board certified medical physicist’s design using dose length product (DLP) and isodose curves. Results: The percentage error found between the physicist’s manual calculation and RadShield’s semi-automated calculation of lead barrier thickness was 3.42% and 21.17% for the DLP and isodose curve methods, respectively. The medical physicist’s selection of calculation points for recommending lead thickness was roughly the same as those found by RadShield for the DLP method but differed greatly using the isodose method. Conclusion: RadShield improves accuracy in calculating air-kerma rate and barrier thickness over manual calculations using isodose curves. Isodose curves were less intuitive and more prone to error for the physicist than inverse square methods. RadShield can now perform shielding design calculations for general scattering bodies for which isodose curves are provided.« less

SU-F-P-53: RadShield: Semi-Automated Shielding Design for CT Using NCRP 147 and Isodose Curves

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeLorenzo, M; Rutel, I; Wu, D

Purpose: Computed tomography (CT) exam rooms are shielded more quickly and accurately compared to manual calculations using RadShield, a semi-automated diagnostic shielding software package. Last year, we presented RadShield’s approach to shielding radiographic and fluoroscopic rooms calculating air kerma rate and barrier thickness at many points on the floor plan and reporting the maximum values for each barrier. RadShield has now been expanded to include CT shielding design using not only NCRP 147 methodology but also by overlaying vendor provided isodose curves onto the floor plan. Methods: The floor plan image is imported onto the RadShield workspace to serve asmore » a template for drawing barriers, occupied regions and CT locations. SubGUIs are used to set design goals, occupancy factors, workload, and overlay isodose curve files. CTDI and DLP methods are solved following NCRP 147. RadShield’s isodose curve method employs radial scanning to extract data point sets to fit kerma to a generalized power law equation of the form K(r) = ar^b. RadShield’s semi-automated shielding recommendations were compared against a board certified medical physicist’s design using dose length product (DLP) and isodose curves. Results: The percentage error found between the physicist’s manual calculation and RadShield’s semi-automated calculation of lead barrier thickness was 3.42% and 21.17% for the DLP and isodose curve methods, respectively. The medical physicist’s selection of calculation points for recommending lead thickness was roughly the same as those found by RadShield for the DLP method but differed greatly using the isodose method. Conclusion: RadShield improves accuracy in calculating air-kerma rate and barrier thickness over manual calculations using isodose curves. Isodose curves were less intuitive and more prone to error for the physicist than inverse square methods. RadShield can now perform shielding design calculations for general scattering bodies for which isodose curves are provided.« less

Independent calculation of monitor units for VMAT and SPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xin; Bush, Karl; Ding, Aiping

Purpose: Dose and monitor units (MUs) represent two important facets of a radiation therapy treatment. In current practice, verification of a treatment plan is commonly done in dose domain, in which a phantom measurement or forward dose calculation is performed to examine the dosimetric accuracy and the MU settings of a given treatment plan. While it is desirable to verify directly the MU settings, a computational framework for obtaining the MU values from a known dose distribution has yet to be developed. This work presents a strategy to calculate independently the MUs from a given dose distribution of volumetric modulatedmore » arc therapy (VMAT) and station parameter optimized radiation therapy (SPORT). Methods: The dose at a point can be expressed as a sum of contributions from all the station points (or control points). This relationship forms the basis of the proposed MU verification technique. To proceed, the authors first obtain the matrix elements which characterize the dosimetric contribution of the involved station points by computing the doses at a series of voxels, typically on the prescription surface of the VMAT/SPORT treatment plan, with unit MU setting for all the station points. An in-house Monte Carlo (MC) software is used for the dose matrix calculation. The MUs of the station points are then derived by minimizing the least-squares difference between doses computed by the treatment planning system (TPS) and that of the MC for the selected set of voxels on the prescription surface. The technique is applied to 16 clinical cases with a variety of energies, disease sites, and TPS dose calculation algorithms. Results: For all plans except the lung cases with large tissue density inhomogeneity, the independently computed MUs agree with that of TPS to within 2.7% for all the station points. In the dose domain, no significant difference between the MC and Eclipse Anisotropic Analytical Algorithm (AAA) dose distribution is found in terms of isodose contours, dose profiles, gamma index, and dose volume histogram (DVH) for these cases. For the lung cases, the MC-calculated MUs differ significantly from that of the treatment plan computed using AAA. However, the discrepancies are reduced to within 3% when the TPS dose calculation algorithm is switched to a transport equation-based technique (Acuros™). Comparison in the dose domain between the MC and Eclipse AAA/Acuros calculation yields conclusion consistent with the MU calculation. Conclusions: A computational framework relating the MU and dose domains has been established. The framework does not only enable them to verify the MU values of the involved station points of a VMAT plan directly in the MU domain but also provide a much needed mechanism to adaptively modify the MU values of the station points in accordance to a specific change in the dose domain.« less

Picante: R tools for integrating phylogenies and ecology.

PubMed

Kembel, Steven W; Cowan, Peter D; Helmus, Matthew R; Cornwell, William K; Morlon, Helene; Ackerly, David D; Blomberg, Simon P; Webb, Campbell O

2010-06-01

Picante is a software package that provides a comprehensive set of tools for analyzing the phylogenetic and trait diversity of ecological communities. The package calculates phylogenetic diversity metrics, performs trait comparative analyses, manipulates phenotypic and phylogenetic data, and performs tests for phylogenetic signal in trait distributions, community structure and species interactions. Picante is a package for the R statistical language and environment written in R and C, released under a GPL v2 open-source license, and freely available on the web (http://picante.r-forge.r-project.org) and from CRAN (http://cran.r-project.org).

Review of reconstruction of radiation incident air kerma by measurement of absorbed dose in tooth enamel with EPR.

PubMed

Wieser, A

2012-03-01

Electron paramagnetic resonance dosimetry with tooth enamel has been proved to be a reliable method to determine retrospectively exposures from photon fields with minimal detectable doses of 100 mGy or lower, which is lower than achievable with cytogenetic dose reconstruction methods. For risk assessment or validating dosimetry systems for specific radiation incidents, the relevant dose from the incident has to be calculated from the total absorbed dose in enamel by subtracting additional dose contributions from the radionuclide content in teeth, natural external background radiation and medical exposures. For calculating organ doses or evaluating dosimetry systems the absorbed dose in enamel from a radiation incident has to be converted to air kerma using dose conversion factors depending on the photon energy spectrum and geometry of the exposure scenario. This paper outlines the approach to assess individual dose contributions to absorbed dose in enamel and calculate individual air kerma of a radiation incident from the absorbed dose in tooth enamel.

Defect printability for high-exposure dose advanced packaging applications

NASA Astrophysics Data System (ADS)

Mikles, Max; Flack, Warren; Nguyen, Ha-Ai; Schurz, Dan

2003-12-01

Pellicles are used in semiconductor lithography to minimize printable defects and reduce reticle cleaning frequency. However, there are a growing number of microlithography applications, such as advanced packaging and nanotechnology, where it is not clear that pellicles always offer a significant benefit. These applications have relatively large critical dimensions and require ultra thick photoresists with extremely high exposure doses. Given that the lithography is performed in Class 100 cleanroom conditions, it is possible that the risk of defects from contamination is sufficiently low that pellicles would not be required on certain process layer reticles. The elimination of the pellicle requirement would provide a cost reduction by saving the original pellicle cost and eliminating future pellicle replacement and repair costs. This study examines the imaging potential of defects with reticle patterns and processes typical for gold-bump and solder-bump advanced packaging lithography. The test reticle consists of 30 to 90 μm octagonal contact patterns representative of advanced packaging reticles. Programmed defects are added that represent the range of particle sizes (3 to 30 μm) normally protected by the pellicle and that are typical of advanced packaging lithography cleanrooms. The reticle is exposed using an Ultratech Saturn Spectrum 300e2 1X stepper on wafers coated with a variety of ultra thick (30 to 100 μm) positive and negative-acting photoresists commonly used in advanced packaging. The experimental results show that in many cases smaller particles continue to be yield issues for the feature size and density typical of advanced packaging processes. For the two negative photoresists studied it appears that a pellicle is not required for protection from defects smaller than 10 to 15 μm depending on the photoresist thickness. Thus the decision on pellicle usage for these materials would need to be made based on the device fabrication process and the cleanliness of a fabrication facility. For the two positive photoresists studied it appears that a pellicle is required to protect from defects down to 3 μm defects depending on the photoresist thickness. This suggests that a pellicle should always be used for these materials. Since a typical fabrication facility would use both positive and negative photoresists it may be advantageous to use pellicles on all reticles simply to avoid confusion. The cost savings of not using a pellicle could easily be outweighed by the yield benefits of using one.

Radiation treatment of pharmaceuticals

NASA Astrophysics Data System (ADS)

Dám, A. M.; Gazsó, L. G.; Kaewpila, S.; Maschek, I.

1996-03-01

Product specific doses were calculated for pharmaceuticals to be radiation treated. Radio-pasteurization dose were determined for some heat sensitive pharmaceutical basic materials (pancreaton, neopancreatin, neopancreatin USP, duodenum extract). Using the new recommendation (ISO standards, Method 1) dose calculations were performed and radiation sterilization doses were determined for aprotinine and heparine Na.

9975 Shipping package component long-term degradation rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daugherty, W. L.

Special nuclear materials are being stored in the K-Area Complex using 3013 containers that are held within Model 9975 shipping packages. The service life for these packages in storage was recently increased from 15 to 20 years, since some of these packages have been stored for nearly 15 years. A strategy is also being developed whereby such storage might be extended beyond 20 years. This strategy is based on recent calculations that support acceptable 9975 package performance for 20 years with internal heat loads up to 19 watts, and identifies a lower heat load limit for which the package componentsmore » should degrade at half the bounding rate or less, thus doubling the effective storage life for these lower wattage packages. The components of the 9975 package that are sensitive to aging under storage conditions are the fiberboard overpack and the O-ring seals, although some degradation of the lead shield and outer drum are also possible. This report summarizes degradation rates applicable to lower heat load storage conditions. In particular, the O-ring seals should provide leak-tight performance for more than 40 years in packages for which their maximum temperature is ≤135 °F. Similarly, the fiberboard should remain acceptable in performance of its required safety functions for up to 40 years in packages with a maximum fiberboard temperature ≤125 °F.« less

Improvements in dose calculation accuracy for small off-axis targets in high dose per fraction tomotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardcastle, Nicholas; Bayliss, Adam; Wong, Jeannie Hsiu Ding

2012-08-15

Purpose: A recent field safety notice from TomoTherapy detailed the underdosing of small, off-axis targets when receiving high doses per fraction. This is due to angular undersampling in the dose calculation gantry angles. This study evaluates a correction method to reduce the underdosing, to be implemented in the current version (v4.1) of the TomoTherapy treatment planning software. Methods: The correction method, termed 'Super Sampling' involved the tripling of the number of gantry angles from which the dose is calculated during optimization and dose calculation. Radiochromic film was used to measure the dose to small targets at various off-axis distances receivingmore » a minimum of 21 Gy in one fraction. Measurements were also performed for single small targets at the center of the Lucy phantom, using radiochromic film and the dose magnifying glass (DMG). Results: Without super sampling, the peak dose deficit increased from 0% to 18% for a 10 mm target and 0% to 30% for a 5 mm target as off-axis target distances increased from 0 to 16.5 cm. When super sampling was turned on, the dose deficit trend was removed and all peak doses were within 5% of the planned dose. For measurements in the Lucy phantom at 9.7 cm off-axis, the positional and dose magnitude accuracy using super sampling was verified using radiochromic film and the DMG. Conclusions: A correction method implemented in the TomoTherapy treatment planning system which triples the angular sampling of the gantry angles used during optimization and dose calculation removes the underdosing for targets as small as 5 mm diameter, up to 16.5 cm off-axis receiving up to 21 Gy.« less

Validation of calculation algorithms for organ doses in CT by measurements on a 5 year old paediatric phantom

NASA Astrophysics Data System (ADS)

Dabin, Jérémie; Mencarelli, Alessandra; McMillan, Dayton; Romanyukha, Anna; Struelens, Lara; Lee, Choonsik

2016-06-01

Many organ dose calculation tools for computed tomography (CT) scans rely on the assumptions: (1) organ doses estimated for one CT scanner can be converted into organ doses for another CT scanner using the ratio of the Computed Tomography Dose Index (CTDI) between two CT scanners; and (2) helical scans can be approximated as the summation of axial slices covering the same scan range. The current study aims to validate experimentally these two assumptions. We performed organ dose measurements in a 5 year-old physical anthropomorphic phantom for five different CT scanners from four manufacturers. Absorbed doses to 22 organs were measured using thermoluminescent dosimeters for head-to-torso scans. We then compared the measured organ doses with the values calculated from the National Cancer Institute dosimetry system for CT (NCICT) computer program, developed at the National Cancer Institute. Whereas the measured organ doses showed significant variability (coefficient of variation (CoV) up to 53% at 80 kV) across different scanner models, the CoV of organ doses normalised to CTDIvol substantially decreased (12% CoV on average at 80 kV). For most organs, the difference between measured and simulated organ doses was within  ±20% except for the bone marrow, breasts and ovaries. The discrepancies were further explained by additional Monte Carlo calculations of organ doses using a voxel phantom developed from CT images of the physical phantom. The results demonstrate that organ doses calculated for one CT scanner can be used to assess organ doses from other CT scanners with 20% uncertainty (k  =  1), for the scan settings considered in the study.

Underestimation of Low-Dose Radiation in Treatment Planning of Intensity-Modulated Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Si Young; Liu, H. Helen; Mohan, Radhe

2008-08-01

Purpose: To investigate potential dose calculation errors in the low-dose regions and identify causes of such errors for intensity-modulated radiotherapy (IMRT). Methods and Materials: The IMRT treatment plans of 23 patients with lung cancer and mesothelioma were reviewed. Of these patients, 15 had severe pulmonary complications after radiotherapy. Two commercial treatment-planning systems (TPSs) and a Monte Carlo system were used to calculate and compare dose distributions and dose-volume parameters of the target volumes and critical structures. The effect of tissue heterogeneity, multileaf collimator (MLC) modeling, beam modeling, and other factors that could contribute to the differences in IMRT dose calculationsmore » were analyzed. Results: In the commercial TPS-generated IMRT plans, dose calculation errors primarily occurred in the low-dose regions of IMRT plans (<50% of the radiation dose prescribed for the tumor). Although errors in the dose-volume histograms of the normal lung were small (<5%) above 10 Gy, underestimation of dose <10 Gy was found to be up to 25% in patients with mesothelioma or large target volumes. These errors were found to be caused by inadequate modeling of MLC transmission and leaf scatter in commercial TPSs. The degree of low-dose errors depends on the target volumes and the degree of intensity modulation. Conclusions: Secondary radiation from MLCs contributes a significant portion of low dose in IMRT plans. Dose underestimation could occur in conventional IMRT dose calculations if such low-dose radiation is not properly accounted for.« less