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Sample records for advanced dose calculation

  1. Dosimetric validation of the Acuros XB Advanced Dose Calculation algorithm: fundamental characterization in water

    NASA Astrophysics Data System (ADS)

    Fogliata, Antonella; Nicolini, Giorgia; Clivio, Alessandro; Vanetti, Eugenio; Mancosu, Pietro; Cozzi, Luca

    2011-03-01

    A new algorithm, Acuros® XB Advanced Dose Calculation, has been introduced by Varian Medical Systems in the Eclipse planning system for photon dose calculation in external radiotherapy. Acuros XB is based on the solution of the linear Boltzmann transport equation (LBTE). The LBTE describes the macroscopic behaviour of radiation particles as they travel through and interact with matter. The implementation of Acuros XB in Eclipse has not been assessed; therefore, it is necessary to perform these pre-clinical validation tests to determine its accuracy. This paper summarizes the results of comparisons of Acuros XB calculations against measurements and calculations performed with a previously validated dose calculation algorithm, the Anisotropic Analytical Algorithm (AAA). The tasks addressed in this paper are limited to the fundamental characterization of Acuros XB in water for simple geometries. Validation was carried out for four different beams: 6 and 15 MV beams from a Varian Clinac 2100 iX, and 6 and 10 MV 'flattening filter free' (FFF) beams from a TrueBeam linear accelerator. The TrueBeam FFF are new beams recently introduced in clinical practice on general purpose linear accelerators and have not been previously reported on. Results indicate that Acuros XB accurately reproduces measured and calculated (with AAA) data and only small deviations were observed for all the investigated quantities. In general, the overall degree of accuracy for Acuros XB in simple geometries can be stated to be within 1% for open beams and within 2% for mechanical wedges. The basic validation of the Acuros XB algorithm was therefore considered satisfactory for both conventional photon beams as well as for FFF beams of new generation linacs such as the Varian TrueBeam.

  2. Monte Carlo calculation of skyshine'' neutron dose from ALS (Advanced Light Source)

    SciTech Connect

    Moin-Vasiri, M.

    1990-06-01

    This report discusses the following topics on skyshine'' neutron dose from ALS: Sources of radiation; ALS modeling for skyshine calculations; MORSE Monte-Carlo; Implementation of MORSE; Results of skyshine calculations from storage ring; and Comparison of MORSE shielding calculations.

  3. Dosimetric validation of the Acuros XB Advanced Dose Calculation algorithm: fundamental characterization in water

    NASA Astrophysics Data System (ADS)

    Fogliata, Antonella; Nicolini, Giorgia; Clivio, Alessandro; Vanetti, Eugenio; Mancosu, Pietro; Cozzi, Luca

    2011-05-01

    This corrigendum intends to clarify some important points that were not clearly or properly addressed in the original paper, and for which the authors apologize. The original description of the first Acuros algorithm is from the developers, published in Physics in Medicine and Biology by Vassiliev et al (2010) in the paper entitled 'Validation of a new grid-based Boltzmann equation solver for dose calculation in radiotherapy with photon beams'. The main equations describing the algorithm reported in our paper, implemented as the 'Acuros XB Advanced Dose Calculation Algorithm' in the Varian Eclipse treatment planning system, were originally described (for the original Acuros algorithm) in the above mentioned paper by Vassiliev et al. The intention of our description in our paper was to give readers an overview of the algorithm, not pretending to have authorship of the algorithm itself (used as implemented in the planning system). Unfortunately our paper was not clear, particularly in not allocating full credit to the work published by Vassiliev et al on the original Acuros algorithm. Moreover, it is important to clarify that we have not adapted any existing algorithm, but have used the Acuros XB implementation in the Eclipse planning system from Varian. In particular, the original text of our paper should have been as follows: On page 1880 the sentence 'A prototype LBTE solver, called Attila (Wareing et al 2001), was also applied to external photon beam dose calculations (Gifford et al 2006, Vassiliev et al 2008, 2010). Acuros XB builds upon many of the methods in Attila, but represents a ground-up rewrite of the solver where the methods were adapted especially for external photon beam dose calculations' should be corrected to 'A prototype LBTE solver, called Attila (Wareing et al 2001), was also applied to external photon beam dose calculations (Gifford et al 2006, Vassiliev et al 2008). A new algorithm called Acuros, developed by the Transpire Inc. group, was

  4. SU-E-T-313: The Accuracy of the Acuros XB Advanced Dose Calculation Algorithm for IMRT Dose Distributions in Head and Neck

    SciTech Connect

    Araki, F; Onizuka, R; Ohno, T; Tomiyama, Y; Hioki, K

    2014-06-01

    Purpose: To investigate the accuracy of the Acuros XB version 11 (AXB11) advanced dose calculation algorithm by comparing with Monte Caro (MC) calculations. The comparisons were performed with dose distributions for a virtual inhomogeneity phantom and intensity-modulated radiotherapy (IMRT) in head and neck. Methods: Recently, AXB based on Linear Boltzmann Transport Equation has been installed in the Eclipse treatment planning system (Varian Medical Oncology System, USA). The dose calculation accuracy of AXB11 was tested by the EGSnrc-MC calculations. In additions, AXB version 10 (AXB10) and Analytical Anisotropic Algorithm (AAA) were also used. First the accuracy of an inhomogeneity correction for AXB and AAA algorithms was evaluated by comparing with MC-calculated dose distributions for a virtual inhomogeneity phantom that includes water, bone, air, adipose, muscle, and aluminum. Next the IMRT dose distributions for head and neck were compared with the AXB and AAA algorithms and MC by means of dose volume histograms and three dimensional gamma analysis for each structure (CTV, OAR, etc.). Results: For dose distributions with the virtual inhomogeneity phantom, AXB was in good agreement with those of MC, except the dose in air region. The dose in air region decreased in order of MCdose kernel of water, the doses in regions for air, bone, and aluminum considerably became higher than those of AXB and MC. The pass rates of the gamma analysis for IMRT dose distributions in head and neck were similar to those of MC in order of AXB11dose calculation accuracy of AXB11 was almost equivalent to the MC dose calculation.

  5. Calculating drug doses.

    PubMed

    2016-09-01

    Numeracy and calculation are key skills for nurses. As nurses are directly accountable for ensuring medicines are prescribed, dispensed and administered safely, they must be able to understand and calculate drug doses. PMID:27615351

  6. Dose Calculation Spreadsheet

    1997-06-10

    VENTSAR XL is an EXCEL Spreadsheet that can be used to calculate downwind doses as a result of a hypothetical atmospheric release. Both building effects and plume rise may be considered. VENTSAR XL will run using any version of Microsoft EXCEL version 4.0 or later. Macros (the programming language of EXCEL) was used to automate the calculations. The user enters a minimal amount of input and the code calculates the resulting concentrations and doses atmore » various downwind distances as specified by the user.« less

  7. 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.

  8. A dose error evaluation study for 4D dose calculations

    NASA Astrophysics Data System (ADS)

    Milz, Stefan; Wilkens, Jan J.; Ullrich, Wolfgang

    2014-10-01

    Previous studies have shown that respiration induced motion is not negligible for Stereotactic Body Radiation Therapy. The intrafractional breathing induced motion influences the delivered dose distribution on the underlying patient geometry such as the lung or the abdomen. If a static geometry is used, a planning process for these indications does not represent the entire dynamic process. The quality of a full 4D dose calculation approach depends on the dose coordinate transformation process between deformable geometries. This article provides an evaluation study that introduces an advanced method to verify the quality of numerical dose transformation generated by four different algorithms. The used transformation metric value is based on the deviation of the dose mass histogram (DMH) and the mean dose throughout dose transformation. The study compares the results of four algorithms. In general, two elementary approaches are used: dose mapping and energy transformation. Dose interpolation (DIM) and an advanced concept, so called divergent dose mapping model (dDMM), are used for dose mapping. The algorithms are compared to the basic energy transformation model (bETM) and the energy mass congruent mapping (EMCM). For evaluation 900 small sample regions of interest (ROI) are generated inside an exemplary lung geometry (4DCT). A homogeneous fluence distribution is assumed for dose calculation inside the ROIs. The dose transformations are performed with the four different algorithms. The study investigates the DMH-metric and the mean dose metric for different scenarios (voxel sizes: 8 mm, 4 mm, 2 mm, 1 mm 9 different breathing phases). dDMM achieves the best transformation accuracy in all measured test cases with 3-5% lower errors than the other models. The results of dDMM are reasonable and most efficient in this study, although the model is simple and easy to implement. The EMCM model also achieved suitable results, but the approach requires a more complex

  9. Beam simulation and radiation dose calculation at the Advanced Photon Source with shower, an Interface Program to the EGS4 code system

    SciTech Connect

    Emery, L.

    1995-07-01

    The interface program shower to the FGS Monte Carlo electromagnetic cascade shower simulation code system was written to facilitate the definition of complicated target and shielding geometries and to simplify the handling of input and output of data. The geometry is defined by a series of namelist commands in an input file. The input and output beam data files follow the SPDDS (self-describing data set) protocol, which makes the files compatible with other physics codes that follow the same protocol. For instance, one can use the results of the cascade shower simulation as the input data for an accelerator tracking code. The shower code has also been used to calculate the bremsstrahlung component of radiation doses for possible beam loss scenarios at the Advanced Photon Source (APS) at Argonne National Laboratory.

  10. Tank Z-361 dose rate calculations

    SciTech Connect

    Richard, R.F.

    1998-09-30

    Neutron and gamma ray dose rates were calculated above and around the 6-inch riser of tank Z-361 located at the Plutonium Finishing Plant. Dose rates were also determined off of one side of the tank. The largest dose rate 0.029 mrem/h was a gamma ray dose and occurred 76.2 cm (30 in.) directly above the open riser. All other dose rates were negligible. The ANSI/ANS 1991 flux to dose conversion factor for neutrons and photons were used in this analysis. Dose rates are reported in units of mrem/h with the calculated uncertainty shown within the parentheses.

  11. 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...

  12. A Program for Calculating Radiation Dose Rates.

    1986-01-27

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

  13. Practical applications of internal dose calculations

    SciTech Connect

    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 describes 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.

  14. Radioactive Dose Assessment and NRC Verification of Licensee Dose Calculation.

    1994-09-16

    Version 00 PCDOSE was developed for the NRC to perform calculations to determine radioactive dose due to the annual averaged offsite release of liquid and gaseous effluent by U.S commercial nuclear power facilities. Using NRC approved dose assessment methodologies, it acts as an inspector's tool for verifying the compliance of the facility's dose assessment software. PCDOSE duplicates the calculations of the GASPAR II mainframe code as well as calculations using the methodologices of Reg. Guidemore » 1.109 Rev. 1 and NUREG-0133 by optional choice.« less

  15. Radioactive Dose Assessment and NRC Verification of Licensee Dose Calculation.

    SciTech Connect

    BOHN, TED S.

    1994-09-16

    Version 00 PCDOSE was developed for the NRC to perform calculations to determine radioactive dose due to the annual averaged offsite release of liquid and gaseous effluent by U.S commercial nuclear power facilities. Using NRC approved dose assessment methodologies, it acts as an inspector's tool for verifying the compliance of the facility's dose assessment software. PCDOSE duplicates the calculations of the GASPAR II mainframe code as well as calculations using the methodologices of Reg. Guide 1.109 Rev. 1 and NUREG-0133 by optional choice.

  16. Georgia fishery study: implications for dose calculations

    SciTech Connect

    Turcotte, M.D.S.

    1983-03-28

    Fish consumption will contribute a major portion of the estimated individual and population doses from L-Reactor liquid releases and Cs-137 remobilization in Steel Creek. It is therefore important that the values for fish consumption used in dose calculations be as realistic as possible. Since publication of the L-Reactor Environmental Information Document (EID), data have become available on sport fishing in the Savannah River. These data provide SRP with site-specific sport fish harvest and consumption values for use in dose calculations. The Georgia fishery data support the total population fish consumption and calculated dose reported in the EID. The data indicate, however, that both the EID average and maximum individual fish consumption have been underestimated, although each to a different degree. The average fish consumption value used in the EID is approximately 3% below the lower limit of the fish consumption range calculated using the Georgia data. A fish consumption value of 11.3 kg/yr should be used to recalculate dose to the average individual from L-Reactor restart. Maximum fish consumption in the EID has been underestimated by approximately 60%, and doses to the maximum individual should also be recalculated. Future dose calculations should utilize an average fish consumption value of 11.3 kg/yr, and a maximum fish consumption value of 34 kg/yr.

  17. Historical river flow rates for dose calculations

    SciTech Connect

    Carlton, W.H.

    1991-06-10

    Annual average river flow rates are required input to the LADTAP Computer Code for calculating offsite doses from liquid releases of radioactive materials to the Savannah River. The source of information on annual river flow rates used in dose calculations varies, depending on whether calculations are for retrospective releases or prospective releases. Examples of these types of releases are: Retrospective - releases from routine operations (annual environmental reports) and short term release incidents that have occurred. Prospective - releases that might be expected in the future from routine or abnormal operation of existing or new facilities (EIS`s, EID`S, SAR`S, etc.). This memorandum provides historical flow rates at the downstream gauging station at Highway 301 for use in retrospective dose calculations and derives flow rate data for the Beaufort-Jasper and Port Wentworth water treatment plants.

  18. Multigroup neutron dose calculations for proton therapy

    SciTech Connect

    Kelsey Iv, Charles T; Prinja, Anil K

    2009-01-01

    We have developed tools for the preparation of coupled multigroup proton/neutron cross section libraries. Our method is to use NJOY to process evaluated nuclear data files for incident particles below 150 MeV and MCNPX to produce data for higher energies. We modified the XSEX3 program of the MCNPX code system to produce Legendre expansions of scattering matrices generated by sampling the physics models that are comparable to the output of the GROUPR routine of NJOY. Our code combines the low and high energy scattering data with user input stopping powers and energy deposition cross sections that we also calculated using MCNPX. Our code also calculates momentum transfer coefficients for the library and optionally applies an energy straggling model to the scattering cross sections and stopping powers. The motivation was initially for deterministic solution of space radiation shielding calculations using Attila, but noting that proton therapy treatment planning may neglect secondary neutron dose assessments because of difficulty and expense, we have also investigated the feasibility of multi group methods for this application. We have shown that multigroup MCNPX solutions for secondary neutron dose compare well with continuous energy solutions and are obtainable with less than half computational cost. This efficiency comparison neglects the cost of preparing the library data, but this becomes negligible when distributed over many multi group calculations. Our deterministic calculations illustrate recognized obstacles that may have to be overcome before discrete ordinates methods can be efficient alternatives for proton therapy neutron dose calculations.

  19. Agriculture-related radiation dose calculations

    SciTech Connect

    Furr, J.M.; Mayberry, J.J.; Waite, D.A.

    1987-10-01

    Estimates of radiation dose to the public must be made at each stage in the identification and qualification process leading to siting a high-level nuclear waste repository. Specifically considering the ingestion pathway, this paper examines questions of reliability and adequacy of dose calculations in relation to five stages of data availability (geologic province, region, area, location, and mass balance) and three methods of calculation (population, population/food production, and food production driven). Calculations were done using the model PABLM with data for the Permian and Palo Duro Basins and the Deaf Smith County area. Extra effort expended in gathering agricultural data at succeeding environmental characterization levels does not appear justified, since dose estimates do not differ greatly; that effort would be better spent determining usage of food types that contribute most to the total dose; and that consumption rate and the air dispersion factor are critical to assessment of radiation dose via the ingestion pathway. 17 refs., 9 figs., 32 tabs.

  20. Calculation of external dose from distributed source

    SciTech Connect

    Kocher, D.C.

    1986-01-01

    This paper discusses a relatively simple calculational method, called the point kernel method (Fo68), for estimating external dose from distributed sources that emit photon or electron radiations. The principles of the point kernel method are emphasized, rather than the presentation of extensive sets of calculations or tables of numerical results. A few calculations are presented for simple source geometries as illustrations of the method, and references and descriptions are provided for other caluclations in the literature. This paper also describes exposure situations for which the point kernel method is not appropriate and other, more complex, methods must be used, but these methods are not discussed in any detail.

  1. Use of Fluka to Create Dose Calculations

    NASA Technical Reports Server (NTRS)

    Lee, Kerry T.; Barzilla, Janet; Townsend, Lawrence; Brittingham, John

    2012-01-01

    Monte Carlo codes provide an effective means of modeling three dimensional radiation transport; however, their use is both time- and resource-intensive. The creation of a lookup table or parameterization from Monte Carlo simulation allows users to perform calculations with Monte Carlo results without replicating lengthy calculations. FLUKA Monte Carlo transport code was used to develop lookup tables and parameterizations for data resulting from the penetration of layers of aluminum, polyethylene, and water with areal densities ranging from 0 to 100 g/cm^2. Heavy charged ion radiation including ions from Z=1 to Z=26 and from 0.1 to 10 GeV/nucleon were simulated. Dose, dose equivalent, and fluence as a function of particle identity, energy, and scattering angle were examined at various depths. Calculations were compared against well-known results and against the results of other deterministic and Monte Carlo codes. Results will be presented.

  2. Validation of Dose Calculation Codes for Clearance

    SciTech Connect

    Menon, S.; Wirendal, B.; Bjerler, J.; Studsvik; Teunckens, L.

    2003-02-27

    Various international and national bodies such as the International Atomic Energy Agency, the European Commission, the US Nuclear Regulatory Commission have put forward proposals or guidance documents to regulate the ''clearance'' from regulatory control of very low level radioactive material, in order to allow its recycling as a material management practice. All these proposals are based on predicted scenarios for subsequent utilization of the released materials. The calculation models used in these scenarios tend to utilize conservative data regarding exposure times and dose uptake as well as other assumptions as a safeguard against uncertainties. None of these models has ever been validated by comparison with the actual real life practice of recycling. An international project was organized in order to validate some of the assumptions made in these calculation models, and, thereby, better assess the radiological consequences of recycling on a practical large scale.

  3. Recommendations for Insulin Dose Calculator Risk Management

    PubMed Central

    2014-01-01

    Several studies have shown the usefulness of an automated insulin dose bolus advisor (BA) in achieving improved glycemic control for insulin-using diabetes patients. Although regulatory agencies have approved several BAs over the past decades, these devices are not standardized in their approach to dosage calculation and include many features that may introduce risk to patients. Moreover, there is no single standard of care for diabetes worldwide and no guidance documents for BAs, specifically. Given the emerging and more stringent regulations on software used in medical devices, the approval process is becoming more difficult for manufacturers to navigate, with some manufacturers opting to remove BAs from their products altogether. A comprehensive literature search was performed, including publications discussing: diabetes BA use and benefit, infusion pump safety and regulation, regulatory submissions, novel BAs, and recommendations for regulation and risk management of BAs. Also included were country-specific and international guidance documents for medical device, infusion pump, medical software, and mobile medical application risk management and regulation. No definitive worldwide guidance exists regarding risk management requirements for BAs, specifically. However, local and international guidance documents for medical devices, infusion pumps, and medical device software offer guidance that can be applied to this technology. In addition, risk management exercises that are algorithm-specific can help prepare manufacturers for regulatory submissions. This article discusses key issues relevant to BA use and safety, and recommends risk management activities incorporating current research and guidance. PMID:24876550

  4. Recommendations for Insulin Dose Calculator Risk Management.

    PubMed

    Rees, Christen

    2014-01-01

    Several studies have shown the usefulness of an automated insulin dose bolus advisor (BA) in achieving improved glycemic control for insulin-using diabetes patients. Although regulatory agencies have approved several BAs over the past decades, these devices are not standardized in their approach to dosage calculation and include many features that may introduce risk to patients. Moreover, there is no single standard of care for diabetes worldwide and no guidance documents for BAs, specifically. Given the emerging and more stringent regulations on software used in medical devices, the approval process is becoming more difficult for manufacturers to navigate, with some manufacturers opting to remove BAs from their products altogether. A comprehensive literature search was performed, including publications discussing: diabetes BA use and benefit, infusion pump safety and regulation, regulatory submissions, novel BAs, and recommendations for regulation and risk management of BAs. Also included were country-specific and international guidance documents for medical device, infusion pump, medical software, and mobile medical application risk management and regulation. No definitive worldwide guidance exists regarding risk management requirements for BAs, specifically. However, local and international guidance documents for medical devices, infusion pumps, and medical device software offer guidance that can be applied to this technology. In addition, risk management exercises that are algorithm-specific can help prepare manufacturers for regulatory submissions. This article discusses key issues relevant to BA use and safety, and recommends risk management activities incorporating current research and guidance. PMID:24876550

  5. 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.

  6. Measurements and calculations of electron dose distributions in circular materials

    NASA Astrophysics Data System (ADS)

    Zhou, Yong; Zhou, Xinzhi; An, Zhu; Zhou, Youyi; Wang, Shiming

    2002-03-01

    In this paper, the absorbed dose distributions of 0.6-2.0 MeV electrons in circular compound materials have been calculated by the calculation method of electron energy deposition in multi-layer media based on bipartition model of electron transport. In addition, the blue cellophane film dosimeters have been used to measure the electron absorbed dose distributions in some circular objects. The calculation results are in agreement with some measurement data. The results indicate the usefulness of the calculation and measurement methods for electron dose monitoring and control in radiation processing of wire and cable.

  7. Study of dose calculation on breast brachytherapy using prism TPS

    NASA Astrophysics Data System (ADS)

    Fendriani, Yoza; Haryanto, Freddy

    2015-09-01

    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 first 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 cm3. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm3. 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.

  8. Proton dose calculation based on in-air fluence measurements.

    PubMed

    Schaffner, Barbara

    2008-03-21

    Proton dose calculation algorithms--as well as photon and electron algorithms--are usually based on configuration measurements taken in a water phantom. The exceptions to this are proton dose calculation algorithms for modulated scanning beams. There, it is usual to measure the spot profiles in air. We use the concept of in-air configuration measurements also for scattering and uniform scanning (wobbling) proton delivery techniques. The dose calculation includes a separate step for the calculation of the in-air fluence distribution per energy layer. The in-air fluence calculation is specific to the technique and-to a lesser extent-design of the treatment machine. The actual dose calculation uses the in-air fluence as input and is generic for all proton machine designs and techniques. PMID:18367787

  9. Proton dose calculation based on in-air fluence measurements

    NASA Astrophysics Data System (ADS)

    Schaffner, Barbara

    2008-03-01

    Proton dose calculation algorithms—as well as photon and electron algorithms—are usually based on configuration measurements taken in a water phantom. The exceptions to this are proton dose calculation algorithms for modulated scanning beams. There, it is usual to measure the spot profiles in air. We use the concept of in-air configuration measurements also for scattering and uniform scanning (wobbling) proton delivery techniques. The dose calculation includes a separate step for the calculation of the in-air fluence distribution per energy layer. The in-air fluence calculation is specific to the technique and—to a lesser extent—design of the treatment machine. The actual dose calculation uses the in-air fluence as input and is generic for all proton machine designs and techniques.

  10. Verification of four-dimensional photon dose calculations.

    PubMed

    Vinogradskiy, Yevgeniy Y; Balter, Peter; Followill, David S; Alvarez, Paola E; White, R Allen; Starkschall, George

    2009-08-01

    Recent work in the area of thoracic treatment planning has been focused on trying to explicitly incorporate patient-specific organ motion in the calculation of dose. Four-dimensional (4D) dose calculation algorithms have been developed and incorporated in a research version of a commercial treatment planning system (Pinnacle3, Philips Medical Systems, Milpitas, CA). Before these 4D dose calculations can be used clinically, it is necessary to verify their accuracy with measurements. The primary purpose of this study therefore was to evaluate and validate the accuracy of a 4D dose calculation algorithm with phantom measurements. A secondary objective was to determine whether the performance of the 4D dose calculation algorithm varied between different motion patterns and treatment plans. Measurements were made using two phantoms: A rigid moving phantom and a deformable phantom. The rigid moving phantom consisted of an anthropomorphic thoracic phantom that rested on a programmable motion platform. The deformable phantom used the same anthropomorphic thoracic phantom with a deformable insert for one of the lungs. Two motion patterns were investigated for each phantom: A sinusoidal motion pattern and an irregular motion pattern extracted from a patient breathing profile. A single-beam plan, a multiple-beam plan, and an intensity-modulated radiation therapy plan were created. Doses were calculated in the treatment planning system using the 4D dose calculation algorithm. Then each plan was delivered to the phantoms and delivered doses were measured using thermoluminescent dosimeters (TLDs) and film. The measured doses were compared to the 4D-calculated doses using a measured-to-calculated TLD ratio and a gamma analysis. A relevant passing criteria (3% for the TLD and 5% /3 mm for the gamma metric) was applied to determine if the 4D dose calculations were accurate to within clinical standards. All the TLD measurements in both phantoms satisfied the passing criteria

  11. Fluence-convolution broad-beam (FCBB) dose calculation.

    PubMed

    Lu, Weiguo; Chen, Mingli

    2010-12-01

    IMRT optimization requires a fast yet relatively accurate algorithm to calculate the iteration dose with small memory demand. In this paper, we present a dose calculation algorithm that approaches these goals. By decomposing the infinitesimal pencil beam (IPB) kernel into the central axis (CAX) component and lateral spread function (LSF) and taking the beam's eye view (BEV), we established a non-voxel and non-beamlet-based dose calculation formula. Both LSF and CAX are determined by a commissioning procedure using the collapsed-cone convolution/superposition (CCCS) method as the standard dose engine. The proposed dose calculation involves a 2D convolution of a fluence map with LSF followed by ray tracing based on the CAX lookup table with radiological distance and divergence correction, resulting in complexity of O(N(3)) both spatially and temporally. This simple algorithm is orders of magnitude faster than the CCCS method. Without pre-calculation of beamlets, its implementation is also orders of magnitude smaller than the conventional voxel-based beamlet-superposition (VBS) approach. We compared the presented algorithm with the CCCS method using simulated and clinical cases. The agreement was generally within 3% for a homogeneous phantom and 5% for heterogeneous and clinical cases. Combined with the 'adaptive full dose correction', the algorithm is well suitable for calculating the iteration dose during IMRT optimization. PMID:21081826

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

    PubMed

    Olsher, Richard H; Van Riper, Kenneth A

    2005-01-01

    In typical realistic scenarios, dose factors due to 60Co contaminated steel, used in consumer products, cannot be approximated by standard exposure geometries. It is then necessary to calculate the effective dose using an appropriate anthropomorphic phantom. MCNP calculations were performed using a MIRD human model in two settings. In the first, a male office worker is sitting in a chair containing contaminated steel, surrounded by contaminated furniture. In the second, a male driver is seated inside an automobile, the steel of which is uniformly contaminated. To accurately calculate the dose to lower body organs, especially the gonads, it was essential to modify the MIRD model to simulate two sitting postures: chair and driving position. The phantom modifications are described, and the results of the calculations are presented. In the case of the automobile scenarios, results are compared to those obtained using an isotropic fluence-to-dose conversion function. PMID:16604666

  13. Verification of Calculated Skin Doses in Postmastectomy Helical Tomotherapy

    SciTech Connect

    Ito, Shima; Parker, Brent C.; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth

    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 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%. Conclusions: The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%.

  14. Gamma Knife radiosurgery with CT image-based dose calculation.

    PubMed

    Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Niranjan, Ajay; Kondziolka, Douglas; Flickinger, John; Lunsford, L Dade; Huq, M Saiful

    2015-01-01

    The Leksell GammaPlan software version 10 introduces a CT image-based segmentation tool for automatic skull definition and a convolution dose calculation algorithm for tissue inhomogeneity correction. The purpose of this work was to evaluate the impact of these new approaches on routine clinical Gamma Knife treatment planning. Sixty-five patients who underwent CT image-guided Gamma Knife radiosurgeries at the University of Pittsburgh Medical Center in recent years were retrospectively investigated. The diagnoses for these cases include trigeminal neuralgia, meningioma, acoustic neuroma, AVM, glioma, and benign and metastatic brain tumors. Dose calculations were performed for each patient with the same dose prescriptions and the same shot arrangements using three different approaches: 1) TMR 10 dose calculation with imaging skull definition; 2) convolution dose calculation with imaging skull definition; 3) TMR 10 dose calculation with conventional measurement-based skull definition. For each treatment matrix, the total treatment time, the target coverage index, the selectivity index, the gradient index, and a set of dose statistics parameters were compared between the three calculations. The dose statistics parameters investigated include the prescription isodose volume, the 12 Gy isodose volume, the minimum, maximum and mean doses on the treatment targets, and the critical structures under consideration. The difference between the convolution and the TMR 10 dose calculations for the 104 treatment matrices were found to vary with the patient anatomy, location of the treatment shots, and the tissue inhomogeneities around the treatment target. An average difference of 8.4% was observed for the total treatment times between the convolution and the TMR algorithms. The maximum differences in the treatment times, the prescription isodose volumes, the 12 Gy isodose volumes, the target coverage indices, the selectivity indices, and the gradient indices from the convolution

  15. Data required for testicular dose calculation during radiotherapy of seminoma

    SciTech Connect

    Mazonakis, Michalis; Kokona, Georgiana; Varveris, Haralambos; Damilakis, John; Gourtsoyiannis, Nicholas

    2006-07-15

    The purpose of this study was to provide the required data for the direct calculation of testicular dose resulting from radiotherapy in patients with seminoma. Paraortic (PA) treatment fields and dog-leg (DL) portals including paraortic and ipsilateral pelvic nodes were simulated on a male anthropomorphic phantom equipped with an artificial testicle. Anterior and posterior irradiations were performed for five different PA and DL field dimensions. Dose measurements were carried out using a calibrated ionization chamber. The dependence of testicular dose upon the distance separating the testicle from the treatment volume and upon the tissue thickness at the entrance point of the beam was investigated. A clamshell lead shield was used to reduce testicular dose. The scattered dose to testicle was measured in nine patients using thermoluminescent dosimeters. Phantom and patient exposures were generated with a 6 MV x-ray beam. Linear and nonlinear regression analysis was employed to obtain formulas describing the relation between the radiation dose to an unshielded and/or shielded testicle with the field size and the distance from the inferior field edge. Correction factors showing the variation of testicular dose with the patient thickness along beam axis were found. Bland-Altman statistical analysis showed that testicular dose obtained by the proposed calculation method may differ from the measured dose value by less than 25%. The current study presents a method providing reasonable estimations of testicular dose for individual patients undergoing PA or DL radiotherapy.

  16. Dose-Response Calculator for ArcGIS

    USGS Publications Warehouse

    Hanser, Steven E.; Aldridge, Cameron L.; Leu, Matthias; Nielsen, Scott E.

    2011-01-01

    The Dose-Response Calculator for ArcGIS is a tool that extends the Environmental Systems Research Institute (ESRI) ArcGIS 10 Desktop application to aid with the visualization of relationships between two raster GIS datasets. A dose-response curve is a line graph commonly used in medical research to examine the effects of different dosage rates of a drug or chemical (for example, carcinogen) on an outcome of interest (for example, cell mutations) (Russell and others, 1982). Dose-response curves have recently been used in ecological studies to examine the influence of an explanatory dose variable (for example, percentage of habitat cover, distance to disturbance) on a predicted response (for example, survival, probability of occurrence, abundance) (Aldridge and others, 2008). These dose curves have been created by calculating the predicted response value from a statistical model at different levels of the explanatory dose variable while holding values of other explanatory variables constant. Curves (plots) developed using the Dose-Response Calculator overcome the need to hold variables constant by using values extracted from the predicted response surface of a spatially explicit statistical model fit in a GIS, which include the variation of all explanatory variables, to visualize the univariate response to the dose variable. Application of the Dose-Response Calculator can be extended beyond the assessment of statistical model predictions and may be used to visualize the relationship between any two raster GIS datasets (see example in tool instructions). This tool generates tabular data for use in further exploration of dose-response relationships and a graph of the dose-response curve.

  17. Study of dose calculation on breast brachytherapy using prism TPS

    SciTech Connect

    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 first 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.

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

    SciTech Connect

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

    1984-05-01

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

  19. Determination of radionuclides and pathways contributing to cumulative dose. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities, Calculation 004

    SciTech Connect

    Napier, B.A.

    1992-12-01

    A series of scoping calculations has been undertaken to evaluate the absolute and relative contributions 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 004) examined the contributions of numerous radionuclides to cumulative dose via environmental exposures and accumulation in foods. Addressed in this calculation were the contributions to organ and effective dose of infants and adults 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 002. This calculation specifically addresses cumulative radiation doses to infants and adults resulting from releases occurring over the period 1945 through 1972.

  20. [An empirical model for calculating electron dose distributions].

    PubMed

    Leistner, H; Schüler, W

    1990-01-01

    Dose-distributions in radiation fields are calculated for purpose of irradiation planning from measured depth dose and cross-distributions predominantly. Especially in electron fields the measuring effort is high to this, because these distributions have to be measured for all occurring irradiation parameters and in many different tissue depths. At the very least it can be shown for the 6...10 MeV electron radiation of the linear accelerator Neptun 10p that all required distributions can be calculated from each separately measured depth dose and cross-distribution. For this depth dose distribution and the measured border decrease of cross-distribution are tabulated and the abscissas are submitted to a linear transformation x' = k.x. In case of depth dose distribution the transformation factor k is dependent on electron energy only and in cross-distribution on tissue depth and source-surface-distance additionally. PMID:2356295

  1. Georgia fishery study: implications for dose calculations. Revision 1

    SciTech Connect

    Turcotte, M.D.S.

    1983-08-05

    Fish consumption will contribute a major portion of the estimated individual and population doses from L-Reactor liquid releases and Cs-137 remobilization in Steel Creek. It is therefore important that the values for fish consumption used in dose calculations be as realistic as possible. Since publication of the L-Reactor Environmental Information Document (EID), data have become available on sport fishing in the Savannah River. These data provide SRP with a site-specific sport fish harvest and consumption values for use in dose calculations. The Georgia fishery data support the total population fish consumption and calculated dose reported in the EID. The data indicate, however, that both the EID average and maximum individual fish consumption have been underestimated, although each to a different degree. The average fish consumption value used in the EID is approximately 3% below the lower limit of the fish consumption range calculated using the Georgia data. Maximum fish consumption in the EID has been underestimated by approximately 60%, and doses to the maximum individual should also be recalculated. Future dose calculations should utilize an average adult fish consumption value of 11.3 kg/yr, and a maximum adult fish consumption value of 34 kg/yr. Consumption values for the teen and child age groups should be increased proportionally: (1) teen average = 8.5; maximum = 25.9 kg/yr; and (2) child average = 3.6; maximum = 11.2 kg/yr. 8 refs.

  2. PLUTONIUM/HIGH-LEVEL VITRIFIED WASTE BDBE DOSE CALCULATION

    SciTech Connect

    J.A. Ziegler

    2000-11-20

    The purpose of this calculation is to provide a dose consequence analysis of high-level waste (HLW) consisting of plutonium immobilized in vitrified HLW to be handled at the proposed Monitored Geologic Repository at Yucca Mountain for a beyond design basis event (BDBE) under expected conditions using best estimate values for each calculation parameter. In addition to the dose calculation, a plutonium respirable particle size for dose calculation use is derived. The current concept for this waste form is plutonium disks enclosed in cans immobilized in canisters of vitrified HLW (i.e., glass). The plutonium inventory at risk used for this calculation is selected from Plutonium Immobilization Project Input for Yucca Mountain Total Systems Performance Assessment (Shaw 1999). The BDBE examined in this calculation is a nonmechanistic initiating event and the sequence of events that follow to cause a radiological release. This analysis will provide the radiological releases and dose consequences for a postulated BDBE. Results may be considered in other analyses to determine or modify the safety classification and quality assurance level of repository structures, systems, and components. This calculation uses best available technical information because the BDBE frequency is very low (i.e., less than 1.0E-6 events/year) and is not required for License Application for the Monitored Geologic Repository. The results of this calculation will not be used as part of a licensing or design basis.

  3. Quantification of Proton Dose Calculation Accuracy in the Lung

    SciTech Connect

    Grassberger, Clemens; Daartz, Juliane; Dowdell, Stephen; Ruggieri, Thomas; Sharp, Greg; Paganetti, Harald

    2014-06-01

    Purpose: To quantify the accuracy of a clinical proton treatment planning system (TPS) as well as Monte Carlo (MC)–based dose calculation through measurements and to assess the clinical impact in a cohort of patients with tumors located in the lung. Methods and Materials: A lung phantom and ion chamber array were used to measure the dose to a plane through a tumor embedded in the lung, and to determine the distal fall-off of the proton beam. Results were compared with TPS and MC calculations. Dose distributions in 19 patients (54 fields total) were simulated using MC and compared to the TPS algorithm. Results: MC increased dose calculation accuracy in lung tissue compared with the TPS and reproduced dose measurements in the target to within ±2%. The average difference between measured and predicted dose in a plane through the center of the target was 5.6% for the TPS and 1.6% for MC. MC recalculations in patients showed a mean dose to the clinical target volume on average 3.4% lower than the TPS, exceeding 5% for small fields. For large tumors, MC also predicted consistently higher V5 and V10 to the normal lung, because of a wider lateral penumbra, which was also observed experimentally. Critical structures located distal to the target could show large deviations, although this effect was highly patient specific. Range measurements showed that MC can reduce range uncertainty by a factor of ∼2: the average (maximum) difference to the measured range was 3.9 mm (7.5 mm) for MC and 7 mm (17 mm) for the TPS in lung tissue. Conclusion: Integration of Monte Carlo dose calculation techniques into the clinic would improve treatment quality in proton therapy for lung cancer by avoiding systematic overestimation of target dose and underestimation of dose to normal lung. In addition, the ability to confidently reduce range margins would benefit all patients by potentially lowering toxicity.

  4. Automatic computed tomography patient dose calculation using DICOM header metadata.

    PubMed

    Jahnen, A; Kohler, S; Hermen, J; Tack, D; Back, C

    2011-09-01

    The present work describes a method that calculates the patient dose values in computed tomography (CT) based on metadata contained in DICOM images in support of patient dose studies. The DICOM metadata is preprocessed to extract necessary calculation parameters. Vendor-specific DICOM header information is harmonized using vendor translation tables and unavailable DICOM tags can be completed with a graphical user interface. CT-Expo, an MS Excel application for calculating the radiation dose, is used to calculate the patient doses. All relevant data and calculation results are stored for further analysis in a relational database. Final results are compiled by utilizing data mining tools. This solution was successfully used for the 2009 CT dose study in Luxembourg. National diagnostic reference levels for standard examinations were calculated based on each of the countries' hospitals. The benefits using this new automatic system saved time as well as resources during the data acquisition and the evaluation when compared with earlier questionnaire-based surveys. PMID:21831868

  5. The effect of dose calculation accuracy on inverse treatment planning

    NASA Astrophysics Data System (ADS)

    Jeraj, Robert; Keall, Paul J.; Siebers, Jeffrey V.

    2002-02-01

    The effect of dose calculation accuracy during inverse treatment planning for intensity modulated radiotherapy (IMRT) was studied in this work. Three dose calculation methods were compared: Monte Carlo, superposition and pencil beam. These algorithms were used to calculate beamlets, which were subsequently used by a simulated annealing algorithm to determine beamlet weights which comprised the optimal solution to the objective function. Three different cases (lung, prostate and head and neck) were investigated and several different objective functions were tested for their effect on inverse treatment planning. It is shown that the use of inaccurate dose calculation introduces two errors in a treatment plan, a systematic error and a convergence error. The systematic error is present because of the inaccuracy of the dose calculation algorithm. The convergence error appears because the optimal intensity distribution for inaccurate beamlets differs from the optimal solution for the accurate beamlets. While the systematic error for superposition was found to be ~1% of Dmax in the tumour and slightly larger outside, the error for the pencil beam method is typically ~5% of Dmax and is rather insensitive to the given objectives. On the other hand, the convergence error was found to be very sensitive to the objective function, is only slightly correlated to the systematic error and should be determined for each case individually. Our results suggest that because of the large systematic and convergence errors, inverse treatment planning systems based on pencil beam algorithms alone should be upgraded either to superposition or Monte Carlo based dose calculations.

  6. Dose calculation and treatment planning for the Brookhaven NCT Facility

    SciTech Connect

    Liu, H.B.; Brugger, R.M.

    1992-12-31

    Consistency of the calculated to measured fluxes and doses in phantoms is important for confidence in treatment planning for Boron Neutron Capture Therapy at the Brookhaven Medical Research Reactor (BMRR). Two phantoms have been used to measure the thermal and epithermal flux and gamma dose distributions for irradiations at the BMRR and these are compared to MCNP calculations. Since MCNP calculations in phantoms or models would be lengthy if the calculations started each time with fission neutrons from the reactor core, a neutron source plane, which was verified by spectrum and flux measurements at the irradiation port, was designed. Measured doses in phantoms are especially important to verify the simulated neutron source plane. Good agreement between the calculated and measured values has been achieved and this neutron source plane is now used to predict flux and dose information for oncologists to form treatment plans as well as designing collimator and room shielding. In addition, a program using MCNP calculated results as input has been developed to predict reliable flux and dose distributions in the central coronal section of a head model for irradiation by the BMRR beam. Dosimetric comparisons and treatment examples are presented.

  7. Dose calculation and treatment planning for the Brookhaven NCT Facility

    SciTech Connect

    Liu, H.B.; Brugger, R.M.

    1992-01-01

    Consistency of the calculated to measured fluxes and doses in phantoms is important for confidence in treatment planning for Boron Neutron Capture Therapy at the Brookhaven Medical Research Reactor (BMRR). Two phantoms have been used to measure the thermal and epithermal flux and gamma dose distributions for irradiations at the BMRR and these are compared to MCNP calculations. Since MCNP calculations in phantoms or models would be lengthy if the calculations started each time with fission neutrons from the reactor core, a neutron source plane, which was verified by spectrum and flux measurements at the irradiation port, was designed. Measured doses in phantoms are especially important to verify the simulated neutron source plane. Good agreement between the calculated and measured values has been achieved and this neutron source plane is now used to predict flux and dose information for oncologists to form treatment plans as well as designing collimator and room shielding. In addition, a program using MCNP calculated results as input has been developed to predict reliable flux and dose distributions in the central coronal section of a head model for irradiation by the BMRR beam. Dosimetric comparisons and treatment examples are presented.

  8. DS86 and DS02 organ dose calculations.

    PubMed

    Kerr, George D

    2012-03-01

    A brief review of the techniques used to calculate organ doses for the atomic-bomb survivors at Hiroshima and Nagasaki is provided using the original dosimetry system 1986 (DS86) and revised dosimetry system 2002 (DS02). The DS02 study was undertaken to address a serious discrepancy between calculated and measured values for neutron activation at Hiroshima that had caused a lack of confidence in the previous dosimetry, designated as DS86. Some potential improvements to the organ dose calculations that were not considered during the DS02 study due to time and funding limitations are recommended in this paper. PMID:21725078

  9. Calculation and prescription of dose for total body irradiation

    SciTech Connect

    Galvin, J.M.

    1983-12-01

    The use of large total body fields creates a unique set of problems that stress the accuracy of techniques routinely used for dose calculation. This paper discusses an approach suggested by the Children's Cancer Study Group (CCSG) for both prescribing the total body irradiation (TBI) dose and calculating the beam-on time or meter set needed to deliver it. It is aimed at guaranteeing the accuracy of the calculation, while at the same time ensuring a high degree of compliance for various CCSG protocols using TBI. Data supporting the various CCSG recommendations are presented.

  10. Verification of IMRT dose calculations using AAA and PBC algorithms in dose buildup regions.

    PubMed

    Oinam, Arun S; Singh, Lakhwant

    2010-01-01

    The purpose of this comparative study was to test the accuracy of anisotropic analytical algorithm (AAA) and pencil beam convolution (PBC) algorithms of Eclipse treatment planning system (TPS) for dose calculations in the low- and high-dose buildup regions. AAA and PBC algorithms were used to create two intensity-modulated radiotherapy (IMRT) plans of the same optimal fluence generated from a clinically simulated oropharynx case in an in-house fabricated head and neck phantom. The TPS computed buildup doses were compared with the corresponding measured doses in the phantom using thermoluminescence dosimeters (TLD 100). Analysis of dose distribution calculated using PBC and AAA shows an increase in gamma value in the dose buildup region indicating large dose deviation. For the surface areas of 1, 50 and 100 cm2, PBC overestimates doses as compared to AAA calculated value in the range of 1.34%-3.62% at 0.6 cm depth, 1.74%-2.96% at 0.4 cm depth, and 1.96%-4.06% at 0.2 cm depth, respectively. In high-dose buildup region, AAA calculated doses were lower by an average of -7.56% (SD = 4.73%), while PBC was overestimated by 3.75% (SD = 5.70%) as compared to TLD measured doses at 0.2 cm depth. However, at 0.4 and 0.6 cm depth, PBC overestimated TLD measured doses by 5.84% (SD = 4.38%) and 2.40% (SD = 4.63%), respectively, while AAA underestimated the TLD measured doses by -0.82% (SD = 4.24%) and -1.10% (SD = 4.14%) at the same respective depth. In low-dose buildup region, both AAA and PBC overestimated the TLD measured doses at all depths except -2.05% (SD = 10.21%) by AAA at 0.2 cm depth. The differences between AAA and PBC at all depths were statistically significant (p < 0.05) in high-dose buildup region, whereas it is not statistically significant in low-dose buildup region. In conclusion, AAA calculated the dose more accurately than PBC in clinically important high-dose buildup region at 0.4 cm and 0.6 cm depths. The use of an orfit cast increases the dose buildup

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

    SciTech Connect

    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 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 Calculation 001.

  12. Macro Monte Carlo for dose calculation of proton beams.

    PubMed

    Fix, Michael K; Frei, Daniel; Volken, Werner; Born, Ernst J; Aebersold, Daniel M; Manser, Peter

    2013-04-01

    Although the Monte Carlo (MC) method allows accurate dose calculation for proton radiotherapy, its usage is limited due to long computing time. In order to gain efficiency, a new macro MC (MMC) technique for proton dose calculations has been developed. The basic principle of the MMC transport is a local to global MC approach. The local simulations using GEANT4 consist of mono-energetic proton pencil beams impinging perpendicularly on slabs of different thicknesses and different materials (water, air, lung, adipose, muscle, spongiosa, cortical bone). During the local simulation multiple scattering, ionization as well as elastic and inelastic interactions have been taken into account and the physical characteristics such as lateral displacement, direction distributions and energy loss have been scored for primary and secondary particles. The scored data from appropriate slabs is then used for the stepwise transport of the protons in the MMC simulation while calculating the energy loss along the path between entrance and exit position. Additionally, based on local simulations the radiation transport of neutrons and the generated ions are included into the MMC simulations for the dose calculations. In order to validate the MMC transport, calculated dose distributions using the MMC transport and GEANT4 have been compared for different mono-energetic proton pencil beams impinging on different phantoms including homogeneous and inhomogeneous situations as well as on a patient CT scan. The agreement of calculated integral depth dose curves is better than 1% or 1 mm for all pencil beams and phantoms considered. For the dose profiles the agreement is within 1% or 1 mm in all phantoms for all energies and depths. The comparison of the dose distribution calculated using either GEANT4 or MMC in the patient also shows an agreement of within 1% or 1 mm. The efficiency of MMC is up to 200 times higher than for GEANT4. The very good level of agreement in the dose comparisons

  13. Macro Monte Carlo for dose calculation of proton beams

    NASA Astrophysics Data System (ADS)

    Fix, Michael K.; Frei, Daniel; Volken, Werner; Born, Ernst J.; Aebersold, Daniel M.; Manser, Peter

    2013-04-01

    Although the Monte Carlo (MC) method allows accurate dose calculation for proton radiotherapy, its usage is limited due to long computing time. In order to gain efficiency, a new macro MC (MMC) technique for proton dose calculations has been developed. The basic principle of the MMC transport is a local to global MC approach. The local simulations using GEANT4 consist of mono-energetic proton pencil beams impinging perpendicularly on slabs of different thicknesses and different materials (water, air, lung, adipose, muscle, spongiosa, cortical bone). During the local simulation multiple scattering, ionization as well as elastic and inelastic interactions have been taken into account and the physical characteristics such as lateral displacement, direction distributions and energy loss have been scored for primary and secondary particles. The scored data from appropriate slabs is then used for the stepwise transport of the protons in the MMC simulation while calculating the energy loss along the path between entrance and exit position. Additionally, based on local simulations the radiation transport of neutrons and the generated ions are included into the MMC simulations for the dose calculations. In order to validate the MMC transport, calculated dose distributions using the MMC transport and GEANT4 have been compared for different mono-energetic proton pencil beams impinging on different phantoms including homogeneous and inhomogeneous situations as well as on a patient CT scan. The agreement of calculated integral depth dose curves is better than 1% or 1 mm for all pencil beams and phantoms considered. For the dose profiles the agreement is within 1% or 1 mm in all phantoms for all energies and depths. The comparison of the dose distribution calculated using either GEANT4 or MMC in the patient also shows an agreement of within 1% or 1 mm. The efficiency of MMC is up to 200 times higher than for GEANT4. The very good level of agreement in the dose comparisons

  14. PCDOSE. Radioactive Dose Assessment and NRC Verification of Licensee Dose Calculation

    SciTech Connect

    Bohn, T.S.

    1991-05-01

    PCDOSE was developed for the Nuclear Regulatory Commission (NRC) to perform calculations to determine radioactive dose due to the annual averaged offsite release of liquid and gaseoues effluent by U.S. commercial nuclear power facilities. Using NRC approved dose assessment methodologies, it acts as an inspector`s tool for verifying the compliance of the facility`s dose assessment software. PCDOSE duplicates the calculations of the GASPAR II mainframe code as well as calculations using the methodologies of Reg. Guide 1.109 Rev. 1 and NUREG-0133 by optional choice.

  15. Calculation of the biological effective dose for piecewise defined dose-rate fits

    SciTech Connect

    Hobbs, Robert F.; Sgouros, George

    2009-03-15

    An algorithmic solution to the biological effective dose (BED) calculation from the Lea-Catcheside formula for a piecewise defined function is presented. Data from patients treated for metastatic thyroid cancer were used to illustrate the solution. The Lea-Catcheside formula for the G-factor of the BED is integrated numerically using a large number of small trapezoidal fits to each integral. The algorithmically calculated BED is compatible with an analytic calculation for a similarly valued exponentially fitted dose-rate plot and is the only resolution for piecewise defined dose-rate functions.

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

    SciTech Connect

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

    2011-01-15

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

  17. Impact of dose calculation algorithm on radiation therapy

    PubMed Central

    Chen, Wen-Zhou; Xiao, Ying; Li, Jun

    2014-01-01

    The quality of radiation therapy depends on the ability to maximize the tumor control probability while minimize the normal tissue complication probability. Both of these two quantities are directly related to the accuracy of dose distributions calculated by treatment planning systems. The commonly used dose calculation algorithms in the treatment planning systems are reviewed in this work. The accuracy comparisons among these algorithms are illustrated by summarizing the highly cited research papers on this topic. Further, the correlation between the algorithms and tumor control probability/normal tissue complication probability values are manifested by several recent studies from different groups. All the cases demonstrate that dose calculation algorithms play a vital role in radiation therapy. PMID:25431642

  18. Beta and gamma dose calculations for PWR and BWR containments

    SciTech Connect

    King, D.B.

    1989-07-01

    Analyses of gamma and beta dose in selected regions in PWR and BWR containment buildings have been performed for a range of fission product releases from selected severe accidents. The objective of this study was to determine the radiation dose that safety-related equipment could experience during the selected severe accident sequences. The resulting dose calculations demonstrate the extent to which design basis accident qualified equipment could also be qualified for the severe accident environments. Surry was chosen as the representative PWR plant while Peach Bottom was selected to represent BWRs. Battelle Columbus Laboratory performed the source term release analyses. The AB epsilon scenario (an intermediate to large LOCA with failure to recover onsite or offsite electrical power) was selected as the base case Surry accident, and the AE scenario (a large break LOCA with one initiating event and a combination of failures in two emergency cooling systems) was selected as the base case Peach Bottom accident. Radionuclide release was bounded for both scenarios by including spray operation and arrested sequences as variations of the base scenarios. Sandia National Laboratories used the source terms to calculate dose to selected containment regions. Scenarios with sprays operational resulted in a total dose comparable to that (2.20 /times/ 10/sup 8/ rads) used in current equipment qualification testing. The base case scenarios resulted in some calculated doses roughly an order of magnitude above the current 2.20 /times/ 10/sup 8/ rad equipment qualification test region. 8 refs., 23 figs., 12 tabs.

  19. Independent dose calculations for commissioning, quality assurance and dose reconstruction of PBS proton therapy

    NASA Astrophysics Data System (ADS)

    Meier, G.; Besson, R.; Nanz, A.; Safai, S.; Lomax, A. J.

    2015-04-01

    Pencil beam scanning proton therapy allows the delivery of highly conformal dose distributions by delivering several thousand pencil beams. These beams have to be individually optimised and accurately delivered requiring a significant quality assurance workload. In this work we describe a toolkit for independent dose calculations developed at Paul Scherrer Institut which allows for dose reconstructions at several points in the treatment workflow. Quality assurance based on reconstructed dose distributions was shown to be favourable to pencil beam by pencil beam comparisons for the detection of delivery uncertainties and estimation of their effects. Furthermore the dose reconstructions were shown to have a sensitivity of the order of or higher than the measurements currently employed in the clinical verification procedures. The design of the independent dose calculation tool allows for a high modifiability of the dose calculation parameters (e.g. depth dose profiles, angular spatial distributions) allowing for a safe environment outside of the clinical treatment planning system for investigating the effect of such parameters on the resulting dose distributions and thus distinguishing between different contributions to measured dose deviations. The presented system could potentially reduce the amount of patient-specific quality assurance measurements which currently constitute a bottleneck in the clinical workflow.

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

    PubMed Central

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

    2011-01-01

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

  1. Calculation of midplane dose for total body irradiation from entrance and exit dose MOSFET measurements.

    PubMed

    Satory, P R

    2012-03-01

    This work is the development of a MOSFET based surface in vivo dosimetry system for total body irradiation patients treated with bilateral extended SSD beams using PMMA missing tissue compensators adjacent to the patient. An empirical formula to calculate midplane dose from MOSFET measured entrance and exit doses has been derived. The dependency of surface dose on the air-gap between the spoiler and the surface was investigated by suspending a spoiler above a water phantom, and taking percentage depth dose measurements (PDD). Exit and entrances doses were measured with MOSFETs in conjunction with midplane doses measured with an ion chamber. The entrance and exit doses were combined using an exponential attenuation formula to give an estimate of midplane dose and were compared to the midplane ion chamber measurement for a range of phantom thicknesses. Having a maximum PDD at the surface simplifies the prediction of midplane dose, which is achieved by ensuring that the air gap between the compensator and the surface is less than 10 cm. The comparison of estimated midplane dose and measured midplane dose showed no dependence on phantom thickness and an average correction factor of 0.88 was found. If the missing tissue compensators are kept within 10 cm of the patient then MOSFET measurements of entrance and exit dose can predict the midplane dose for the patient. PMID:22298238

  2. Monte Carlo dose calculation in dental amalgam phantom

    PubMed Central

    Aziz, Mohd. Zahri Abdul; Yusoff, A. L.; Osman, N. D.; Abdullah, R.; Rabaie, N. A.; Salikin, M. S.

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation. PMID:26500401

  3. Monte Carlo dose calculation in dental amalgam phantom.

    PubMed

    Aziz, Mohd Zahri Abdul; Yusoff, A L; Osman, N D; Abdullah, R; Rabaie, N A; Salikin, M S

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation. PMID:26500401

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

    NASA Astrophysics Data System (ADS)

    Poon, Emily S.

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

  5. A Monte Carlo dose calculation tool for radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Li, J. S.; Pawlicki, T.; Jiang, S. B.; Deng, J.; Lee, M. C.; Koumrian, T.; Luxton, M.; Brain, S.

    2002-05-01

    A Monte Carlo user code, MCDOSE, has been developed for radiotherapy treatment planning (RTP) dose calculations. MCDOSE is designed as a dose calculation module suitable for adaptation to host RTP systems. MCDOSE can be used for both conventional photon/electron beam calculation and intensity modulated radiotherapy (IMRT) treatment planning. MCDOSE uses a multiple-source model to reconstruct the treatment beam phase space. Based on Monte Carlo simulated or measured beam data acquired during commissioning, source-model parameters are adjusted through an automated procedure. Beam modifiers such as jaws, physical and dynamic wedges, compensators, blocks, electron cut-outs and bolus are simulated by MCDOSE together with a 3D rectilinear patient geometry model built from CT data. Dose distributions calculated using MCDOSE agreed well with those calculated by the EGS4/DOSXYZ code using different beam set-ups and beam modifiers. Heterogeneity correction factors for layered-lung or layered-bone phantoms as calculated by both codes were consistent with measured data to within 1%. The effect of energy cut-offs for particle transport was investigated. Variance reduction techniques were implemented in MCDOSE to achieve a speedup factor of 10-30 compared to DOSXYZ.

  6. Tissue Heterogeneity in IMRT Dose Calculation for Lung Cancer

    SciTech Connect

    Pasciuti, Katia; Iaccarino, Giuseppe; Strigari, Lidia; Malatesta, Tiziana; Benassi, Marcello; Di Nallo, Anna Maria; Mirri, Alessandra; Pinzi, Valentina; Landoni, Valeria

    2011-07-01

    The aim of this study was to evaluate the differences in accuracy of dose calculation between 3 commonly used algorithms, the Pencil Beam algorithm (PB), the Anisotropic Analytical Algorithm (AAA), and the Collapsed Cone Convolution Superposition (CCCS) for intensity-modulated radiation therapy (IMRT). The 2D dose distributions obtained with the 3 algorithms were compared on each CT slice pixel by pixel, using the MATLAB code (The MathWorks, Natick, MA) and the agreement was assessed with the {gamma} function. The effect of the differences on dose-volume histograms (DVHs), tumor control, and normal tissue complication probability (TCP and NTCP) were also evaluated, and its significance was quantified by using a nonparametric test. In general PB generates regions of over-dosage both in the lung and in the tumor area. These differences are not always in DVH of the lung, although the Wilcoxon test indicated significant differences in 2 of 4 patients. Disagreement in the lung region was also found when the {Gamma} analysis was performed. The effect on TCP is less important than for NTCP because of the slope of the curve at the level of the dose of interest. The effect of dose calculation inaccuracy is patient-dependent and strongly related to beam geometry and to the localization of the tumor. When multiple intensity-modulated beams are used, the effect of the presence of the heterogeneity on dose distribution may not always be easily predictable.

  7. Tissue heterogeneity in IMRT dose calculation for lung cancer.

    PubMed

    Pasciuti, Katia; Iaccarino, Giuseppe; Strigari, Lidia; Malatesta, Tiziana; Benassi, Marcello; Di Nallo, Anna Maria; Mirri, Alessandra; Pinzi, Valentina; Landoni, Valeria

    2011-01-01

    The aim of this study was to evaluate the differences in accuracy of dose calculation between 3 commonly used algorithms, the Pencil Beam algorithm (PB), the Anisotropic Analytical Algorithm (AAA), and the Collapsed Cone Convolution Superposition (CCCS) for intensity-modulated radiation therapy (IMRT). The 2D dose distributions obtained with the 3 algorithms were compared on each CT slice pixel by pixel, using the MATLAB code (The MathWorks, Natick, MA) and the agreement was assessed with the γ function. The effect of the differences on dose-volume histograms (DVHs), tumor control, and normal tissue complication probability (TCP and NTCP) were also evaluated, and its significance was quantified by using a nonparametric test. In general PB generates regions of over-dosage both in the lung and in the tumor area. These differences are not always in DVH of the lung, although the Wilcoxon test indicated significant differences in 2 of 4 patients. Disagreement in the lung region was also found when the Γ analysis was performed. The effect on TCP is less important than for NTCP because of the slope of the curve at the level of the dose of interest. The effect of dose calculation inaccuracy is patient-dependent and strongly related to beam geometry and to the localization of the tumor. When multiple intensity-modulated beams are used, the effect of the presence of the heterogeneity on dose distribution may not always be easily predictable. PMID:20970989

  8. Treatment planning and dose calculation in radiation ecology

    SciTech Connect

    Bentel, G.C.; Nelson, C.E.; Noell, K.T.

    1989-01-01

    This book focuses on treatment planning of cancer therapy. The following topics are discussed: elements of clinical radiation oncology; radiation physics; dose calculation for external beams; pretreatment procedures; brachytherapy; principles of external beam treatment planning; practical treatment planning; and normal tissue consequences. Eight chapters have been processed separately for inclusion in the appropriate data bases.

  9. Assessing the Clinical Impact of Approximations in Analytical Dose Calculations for Proton Therapy

    SciTech Connect

    Schuemann, Jan Giantsoudi, Drosoula; Grassberger, Clemens; Moteabbed, Maryam; Min, Chul Hee; Paganetti, Harald

    2015-08-01

    Purpose: To assess the impact of approximations in current analytical dose calculation methods (ADCs) on tumor control probability (TCP) in proton therapy. Methods: Dose distributions planned with ADC were compared with delivered dose distributions as determined by Monte Carlo simulations. A total of 50 patients were investigated in this analysis with 10 patients per site for 5 treatment sites (head and neck, lung, breast, prostate, liver). Differences were evaluated using dosimetric indices based on a dose-volume histogram analysis, a γ-index analysis, and estimations of TCP. Results: We found that ADC overestimated the target doses on average by 1% to 2% for all patients considered. The mean dose, D95, D50, and D02 (the dose value covering 95%, 50% and 2% of the target volume, respectively) were predicted within 5% of the delivered dose. The γ-index passing rate for target volumes was above 96% for a 3%/3 mm criterion. Differences in TCP were up to 2%, 2.5%, 6%, 6.5%, and 11% for liver and breast, prostate, head and neck, and lung patients, respectively. Differences in normal tissue complication probabilities for bladder and anterior rectum of prostate patients were less than 3%. Conclusion: Our results indicate that current dose calculation algorithms lead to underdosage of the target by as much as 5%, resulting in differences in TCP of up to 11%. To ensure full target coverage, advanced dose calculation methods like Monte Carlo simulations may be necessary in proton therapy. Monte Carlo simulations may also be required to avoid biases resulting from systematic discrepancies in calculated dose distributions for clinical trials comparing proton therapy with conventional radiation therapy.

  10. Assessing the clinical impact of approximations in analytical dose calculations for proton therapy

    PubMed Central

    Schuemann, J.; Giantsoudi, D.; Grassberger, C.; Moteabbed, M.; Min, C.H.; Paganetti, H.

    2015-01-01

    Purpose To assess the impact of approximations in current analytical dose calculation methods (ADCs) on tumor control probability (TCP) in proton therapy. Methods Dose distributions planned with ADC were compared to delivered dose distributions (as determined by Monte Carlo simulations). A total of 50 patients were investigated in this analysis with 10 patients per site for 5 treatment sites (head-and-neck, lung, breast, prostate, liver). Differences were evaluated using dosimetric indices based on a dose-volume-histogram analysis, a γ-index analysis and estimations of TCP. Results We find that ADC overestimates the target doses on average by 1–2% for all patients considered. The mean dose, D95, D50 and D02 (the dose value covering 95%, 50% and 2% of the target volume, respectively) are predicted within 5% of the delivered dose. The γ-index passing rate for target volumes was above 96% for a 3%/3mm criteria. Differences in TCP were up to 2%, 2.5%, 6%, 6.5%, and 11% for liver and breast, prostate, head-and-neck and lung patients, respectively. Differences in normal tissue complication probabilities for bladder and anterior-rectum of prostate patients were less than 3%. Conclusion Our results indicate that current dose calculation algorithms lead to underdosage of the target by as much as 5%, resulting in differences in TCP of up to 11%. In order to ensure full target coverage, advanced dose-calculation methods like Monte Carlo simulations may be necessary in proton therapy. Monte Carlo simulations may also be required in order to avoid biases due to systematic discrepancies in calculated dose distributions for clinical trials comparing proton therapy to conventional radiotherapy. PMID:26025779

  11. Dose Calculation Evolution for Internal Organ Irradiation in Humans

    NASA Astrophysics Data System (ADS)

    Jimenez V., Reina A.

    2007-10-01

    The International Commission of Radiation Units (ICRU) has established through the years, a discrimination system regarding the security levels on the prescription and administration of doses in radiation treatments (Radiotherapy, Brach therapy, Nuclear Medicine). The first level is concerned with the prescription and posterior assurance of dose administration to a point of interest (POI), commonly located at the geometrical center of the region to be treated. In this, the effects of radiation around that POI, is not a priority. The second level refers to the dose specifications in a particular plane inside the patient, mostly the middle plane of the lesion. The dose is calculated to all the structures in that plane regardless if they are tumor or healthy tissue. In this case, the dose is not represented by a point value, but by level curves called "isodoses" as in a topographic map, so you can assure the level of doses to this particular plane, but it also leave with no information about how this values go thru adjacent planes. This is why the third level is referred to the volumetrical description of doses so these isodoses construct now a volume (named "cloud") that give us better assurance about tissue irradiation around the volume of the lesion and its margin (sub clinical spread or microscopic illness). This work shows how this evolution has resulted, not only in healthy tissue protection improvement but in a rise of tumor control, quality of life, better treatment tolerance and minimum permanent secuelae.

  12. Dose Calculation Evolution for Internal Organ Irradiation in Humans

    SciTech Connect

    Jimenez V, Reina A.

    2007-10-26

    The International Commission of Radiation Units (ICRU) has established through the years, a discrimination system regarding the security levels on the prescription and administration of doses in radiation treatments (Radiotherapy, Brach therapy, Nuclear Medicine). The first level is concerned with the prescription and posterior assurance of dose administration to a point of interest (POI), commonly located at the geometrical center of the region to be treated. In this, the effects of radiation around that POI, is not a priority. The second level refers to the dose specifications in a particular plane inside the patient, mostly the middle plane of the lesion. The dose is calculated to all the structures in that plane regardless if they are tumor or healthy tissue. In this case, the dose is not represented by a point value, but by level curves called 'isodoses' as in a topographic map, so you can assure the level of doses to this particular plane, but it also leave with no information about how this values go thru adjacent planes. This is why the third level is referred to the volumetrical description of doses so these isodoses construct now a volume (named 'cloud') that give us better assurance about tissue irradiation around the volume of the lesion and its margin (sub clinical spread or microscopic illness). This work shows how this evolution has resulted, not only in healthy tissue protection improvement but in a rise of tumor control, quality of life, better treatment tolerance and minimum permanent secuelae.

  13. Internal dose conversion factors for calculation of dose to the public

    SciTech Connect

    Not Available

    1988-07-01

    This publication contains 50-year committed dose equivalent factors, in tabular form. The document is intended to be used as the primary reference by the US Department of Energy (DOE) and its contractors for calculating radiation dose equivalents for members of the public, resulting from ingestion or inhalation of radioactive materials. Its application is intended specifically for such materials released to the environment during routine DOE operations, except in those instances where compliance with 40 CFR 61 (National Emission Standards for Hazardous Air Pollutants) requires otherwise. However, the calculated values may be equally applicable to unusual releases or to occupational exposures. The use of these committed dose equivalent tables should ensure that doses to members of the public from internal exposures are calculated in a consistent manner at all DOE facilities.

  14. PLUTONIUM/HIGH LEVEL VITRIFIED WASTE - DBE OFFSITE DOSE CALCULATION

    SciTech Connect

    S. O. Bader

    1999-09-20

    The purpose of this calculation is to provide a bounding dose consequence analysis of the immobilized plutonium (can-in-canister) waste form to be handled at the Monitored Geologic Repository (MGR) at Yucca Mountain. The current concept for the Plutonium Can-in-Canister waste form is provided in Attachment III. A typical design basis event (DBE) defines a scenario that generally includes an initiating event and the sequences of events that follow. This analysis will provide (1) radiological releases and dose consequences for a postulated, bounding DBE and (2) design-related assumptions on which the calculated dose consequences are based. This analysis is part of the safety design basis for the repository. Results will be used in other analyses to determine or modify the safety classification and quality assurance level of repository structures, systems, and components (SSCs). The Quality Assurance (QA) program applies to this calculation. The work reported in this document is part of the analysis of MGR DBEs and is performed using AP-3.12Q, Calculations. The work done for this analysis was evaluated according to QAP-2-0, Control of Activities. This evaluation determined that such activities are subject to DOE/RW/0333PY Quality Assurance Requirements and Description (DOE 1998), requirements. This calculation is quality affecting because the results may be used to support analyses of repository SSCs per QAP-2-3, Classification of Permanent Items.

  15. Fast optimization and dose calculation in scanned ion beam therapy

    SciTech Connect

    Hild, S.; Graeff, C.; Trautmann, J.; Kraemer, M.; Zink, K.; Durante, M.; Bert, C.

    2014-07-15

    Purpose: Particle therapy (PT) has advantages over photon irradiation on static tumors. An increased biological effectiveness and active target conformal dose shaping are strong arguments for PT. However, the sensitivity to changes of internal geometry complicates the use of PT for moving organs. In case of interfractionally moving objects adaptive radiotherapy (ART) concepts known from intensity modulated radiotherapy (IMRT) can be adopted for PT treatments. One ART strategy is to optimize a new treatment plan based on daily image data directly before a radiation fraction is delivered [treatment replanning (TRP)]. Optimizing treatment plans for PT using a scanned beam is a time consuming problem especially for particles other than protons where the biological effective dose has to be calculated. For the purpose of TRP, fast optimization and fast dose calculation have been implemented into the GSI in-house treatment planning system (TPS) TRiP98. Methods: This work reports about the outcome of a code analysis that resulted in optimization of the calculation processes as well as implementation of routines supporting parallel execution of the code. To benchmark the new features, the calculation time for therapy treatment planning has been studied. Results: Compared to the original version of the TPS, calculation times for treatment planning (optimization and dose calculation) have been improved by a factor of 10 with code optimization. The parallelization of the TPS resulted in a speedup factor of 12 and 5.5 for the original version and the code optimized version, respectively. Hence the total speedup of the new implementation of the authors' TPS yielded speedup factors up to 55. Conclusions: The improved TPS is capable of completing treatment planning for ion beam therapy of a prostate irradiation considering organs at risk in this has been overseen in the review process. Also see below 6 min.

  16. External dose-rate conversion factors for calculation of dose to the public

    SciTech Connect

    Not Available

    1988-07-01

    This report presents a tabulation of dose-rate conversion factors for external exposure to photons and electrons emitted by radionuclides in the environment. This report was prepared in conjunction with criteria for limiting dose equivalents to members of the public from operations of the US Department of Energy (DOE). The dose-rate conversion factors are provided for use by the DOE and its contractors in performing calculations of external dose equivalents to members of the public. The dose-rate conversion factors for external exposure to photons and electrons presented in this report are based on a methodology developed at Oak Ridge National Laboratory. However, some adjustments of the previously documented methodology have been made in obtaining the dose-rate conversion factors in this report. 42 refs., 1 fig., 4 tabs.

  17. Monte Carlo dose calculations for phantoms with hip prostheses

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  18. A convolution-superposition dose calculation engine for GPUs

    SciTech Connect

    Hissoiny, Sami; Ozell, Benoit; Despres, Philippe

    2010-03-15

    Purpose: Graphic processing units (GPUs) are increasingly used for scientific applications, where their parallel architecture and unprecedented computing power density can be exploited to accelerate calculations. In this paper, a new GPU implementation of a convolution/superposition (CS) algorithm is presented. Methods: This new GPU implementation has been designed from the ground-up to use the graphics card's strengths and to avoid its weaknesses. The CS GPU algorithm takes into account beam hardening, off-axis softening, kernel tilting, and relies heavily on raytracing through patient imaging data. Implementation details are reported as well as a multi-GPU solution. Results: An overall single-GPU acceleration factor of 908x was achieved when compared to a nonoptimized version of the CS algorithm implemented in PlanUNC in single threaded central processing unit (CPU) mode, resulting in approximatively 2.8 s per beam for a 3D dose computation on a 0.4 cm grid. A comparison to an established commercial system leads to an acceleration factor of approximately 29x or 0.58 versus 16.6 s per beam in single threaded mode. An acceleration factor of 46x has been obtained for the total energy released per mass (TERMA) calculation and a 943x acceleration factor for the CS calculation compared to PlanUNC. Dose distributions also have been obtained for a simple water-lung phantom to verify that the implementation gives accurate results. Conclusions: These results suggest that GPUs are an attractive solution for radiation therapy applications and that careful design, taking the GPU architecture into account, is critical in obtaining significant acceleration factors. These results potentially can have a significant impact on complex dose delivery techniques requiring intensive dose calculations such as intensity-modulated radiation therapy (IMRT) and arc therapy. They also are relevant for adaptive radiation therapy where dose results must be obtained rapidly.

  19. Implementation of Monte Carlo Dose calculation for CyberKnife treatment planning

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Li, J. S.; Deng, J.; Fan, J.

    2008-02-01

    Accurate dose calculation is essential to advanced stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) especially for treatment planning involving heterogeneous patient anatomy. This paper describes the implementation of a fast Monte Carlo dose calculation algorithm in SRS/SRT treatment planning for the CyberKnife® SRS/SRT system. A superposition Monte Carlo algorithm is developed for this application. Photon mean free paths and interaction types for different materials and energies as well as the tracks of secondary electrons are pre-simulated using the MCSIM system. Photon interaction forcing and splitting are applied to the source photons in the patient calculation and the pre-simulated electron tracks are repeated with proper corrections based on the tissue density and electron stopping powers. Electron energy is deposited along the tracks and accumulated in the simulation geometry. Scattered and bremsstrahlung photons are transported, after applying the Russian roulette technique, in the same way as the primary photons. Dose calculations are compared with full Monte Carlo simulations performed using EGS4/MCSIM and the CyberKnife treatment planning system (TPS) for lung, head & neck and liver treatments. Comparisons with full Monte Carlo simulations show excellent agreement (within 0.5%). More than 10% differences in the target dose are found between Monte Carlo simulations and the CyberKnife TPS for SRS/SRT lung treatment while negligible differences are shown in head and neck and liver for the cases investigated. The calculation time using our superposition Monte Carlo algorithm is reduced up to 62 times (46 times on average for 10 typical clinical cases) compared to full Monte Carlo simulations. SRS/SRT dose distributions calculated by simple dose algorithms may be significantly overestimated for small lung target volumes, which can be improved by accurate Monte Carlo dose calculations.

  20. Development of mathematical pediatric phantoms for internal dose calculations: designs, limitations, and prospects

    SciTech Connect

    Cristy, M.

    1980-01-01

    Mathematical phantoms of the human body at various ages are employed with Monte Carlo radiation transport codes for calculation of photon specific absorbed fractions. The author has developed a pediatric phantom series based on the design of the adult phantom, but with explicit equations for each organ so that organ sizes and marrow distributions could be assigned properly. Since the phantoms comprise simple geometric shapes, predictive dose capability is limited when geometry is critical to the calculation. Hence, there is a demand for better phantom design in situations where geometry is critical, such as for external irradiation or for internal emitters with low energy photons. Recent advances in computerized axial tomography (CAT) present the potential for derivation of anatomical information, which is so critical to development of phantoms, and ongoing developmental work on compuer architecture to handle large arrays for Monte Carlo calculations should make complex-geometry dose calculations economically feasible within this decade.

  1. NAC-1 cask dose rate calculations for LWR spent fuel

    SciTech Connect

    CARLSON, A.B.

    1999-02-24

    A Nuclear Assurance Corporation nuclear fuel transport cask, NAC-1, is being considered as a transport and storage option for spent nuclear fuel located in the B-Cell of the 324 Building. The loaded casks will be shipped to the 200 East Area Interim Storage Area for dry interim storage. Several calculations were performed to assess the photon and neutron dose rates. This report describes the analytical methods, models, and results of this investigation.

  2. Monte Carlo Code System for Electron (Positron) Dose Kernel Calculations.

    SciTech Connect

    CHIBANI, OMAR

    1999-05-12

    Version 00 KERNEL performs dose kernel calculations for an electron (positron) isotropic point source in an infinite homogeneous medium. First, the auxiliary code PRELIM is used to prepare cross section data for the considered medium. Then the KERNEL code simulates the transport of electrons and bremsstrahlung photons through the medium until all particles reach their cutoff energies. The deposited energy is scored in concentric spherical shells at a radial distance ranging from zero to twice the source particle range.

  3. Verification of the VARSKIN beta skin dose calculation computer code.

    PubMed

    Sherbini, Sami; DeCicco, Joseph; Gray, Anita Turner; Struckmeyer, Richard

    2008-06-01

    The computer code VARSKIN is used extensively to calculate dose to the skin resulting from contaminants on the skin or on protective clothing covering the skin. The code uses six pre-programmed source geometries, four of which are volume sources, and a wide range of user-selectable radionuclides. Some verification of this code had been carried out before the current version of the code, version 3.0, was released, but this was limited in extent and did not include all the source geometries that the code is capable of modeling. This work extends this verification to include all the source geometries that are programmed in the code over a wide range of beta radiation energies and skin depths. Verification was carried out by comparing the doses calculated using VARSKIN with the doses for similar geometries calculated using the Monte Carlo radiation transport code MCNP5. Beta end-point energies used in the calculations ranged from 0.3 MeV up to 2.3 MeV. The results showed excellent agreement between the MCNP and VARSKIN calculations, with the agreement being within a few percent for point and disc sources and within 20% for other sources with the exception of a few cases, mainly at the low end of the beta end-point energies. The accuracy of the VARSKIN results, based on the work in this paper, indicates that it is sufficiently accurate for calculation of skin doses resulting from skin contaminations, and that the uncertainties arising from the use of VARSKIN are likely to be small compared with other uncertainties that typically arise in this type of dose assessment, such as those resulting from a lack of exact information on the size, shape, and density of the contaminant, the depth of the sensitive layer of the skin at the location of the contamination, the duration of the exposure, and the possibility of the source moving over various areas of the skin during the exposure period if the contaminant is on protective clothing. PMID:18469586

  4. Off-center ratios for three-dimensional dose calculations

    SciTech Connect

    Chui, C.S.; Mohan, R.

    1986-05-01

    A new method is proposed for computing the off-center ratios (OCR's) in three-dimensional dose calculations. For an open field, the OCR at a point is computed as the product of the primary OCR (POCR) and the boundary factors (BF's). The POCR describes the beam profile for an infinite field, that is, without the effect of the collimators. It is defined as the ratio of the dose at a point off the central ray to the dose at the point on the central ray at the same depth for an infinite field. The POCR is a function of radial distance from the beam central ray and depth. The BF describes the shape of the beam in the neighborhood of the field boundary defined by the collimators. It is defined as the ratio of the OCR at a point for a finite field to the OCR at the same point for an infinite field. The BF is a function of distance from the field boundary, depth, and field size. For a wedged field, we assume that the boundary factors remain the same as for open fields but the POCR's are altered. The changes in beam profiles are described by a factor called the wedge profile factor (WPF), defined as the ratio of the dose at a point for the largest wedged field to the dose at the same point for an open field of the same field size. The WPF is a function of lateral distance from the beam central plane and depth. Calculated OCR's using this new method are in agreement with the measured data along both the transverse and the diagonal directions of the field.

  5. Dose calculation software for helical tomotherapy, utilizing patient CT data to calculate an independent three-dimensional dose cube

    SciTech Connect

    Thomas, Simon J.; Eyre, Katie R.; Tudor, G. Samuel J.; Fairfoul, Jamie

    2012-01-15

    Purpose: Treatment plans for the TomoTherapy unit are produced with a planning system that is integral to the unit. The authors have produced an independent dose calculation system, to enable plans to be recalculated in three dimensions, using the patient's CT data. Methods: Software has been written using MATLAB. The DICOM-RT plan object is used to determine the treatment parameters used, including the treatment sinogram. Each projection of the sinogram is segmented and used to calculate dose at multiple calculation points in a three-dimensional grid using tables of measured beam data. A fast ray-trace algorithm is used to determine effective depth for each projection angle at each calculation point. Calculations were performed on a standard desktop personal computer, with a 2.6 GHz Pentium, running Windows XP. Results: The time to perform a calculation, for 3375 points averaged 1 min 23 s for prostate plans and 3 min 40 s for head and neck plans. The mean dose within the 50% isodose was calculated and compared with the predictions of the TomoTherapy planning system. When the modified CT (which includes the TomoTherapy couch) was used, the mean difference for ten prostate patients, was -0.4% (range -0.9% to +0.3%). With the original CT (which included the CT couch), the mean difference was -1.0% (range -1.7% to 0.0%). The number of points agreeing with a gamma 3%/3 mm averaged 99.2% with the modified CT, 96.3% with the original CT. For ten head and neck patients, for the modified and original CT, respectively, the mean difference was +1.1% (range -0.4% to +3.1%) and 1.1% (range -0.4% to +3.0%) with 94.4% and 95.4% passing a gamma 4%/4 mm. The ability of the program to detect a variety of simulated errors has been tested. Conclusions: By using the patient's CT data, the independent dose calculation performs checks that are not performed by a measurement in a cylindrical phantom. This enables it to be used either as an additional check or to replace phantom

  6. Comparing the accuracy of four-dimensional photon dose calculations with three-dimensional calculations using moving and deforming phantoms

    SciTech Connect

    Vinogradskiy, Yevgeniy Y.; Balter, Peter; Followill, David S.; Alvarez, Paola E.; White, R. Allen; Starkschall, George

    2009-11-15

    Purpose: Four-dimensional (4D) dose calculation algorithms, which explicitly incorporate respiratory motion in the calculation of doses, have the potential to improve the accuracy of dose calculations in thoracic treatment planning; however, they generally require greater computing power and resources than currently used for three-dimensional (3D) dose calculations. The purpose of this work was to quantify the increase in accuracy of 4D dose calculations versus 3D dose calculations. Methods: The accuracy of each dose calculation algorithm was assessed using measurements made with two phantoms. Specifically, the authors used a rigid moving anthropomorphic thoracic phantom and an anthropomorphic thoracic phantom with a deformable lung insert. To incorporate a clinically relevant range of scenarios, they programed the phantoms to move and deform with two motion patterns: A sinusoidal motion pattern and an irregular motion pattern that was extracted from an actual patient's breathing profile. For each combination of phantom and motion pattern, three plans were created: A single-beam plan, a multiple-beam plan, and an intensity-modulated radiation therapy plan. Doses were calculated using 4D dose calculation methods as well as conventional 3D dose calculation methods. The rigid moving and deforming phantoms were irradiated according to the three treatment plans and doses were measured using thermoluminescent dosimeters (TLDs) and radiochromic film. The accuracy of each dose calculation algorithm was assessed using measured-to-calculated TLD doses and a {gamma} analysis. Results: No significant differences were observed between the measured-to-calculated TLD ratios among 4D and 3D dose calculations. The {gamma} results revealed that 4D dose calculations had significantly greater percentage of pixels passing the 5%/3 mm criteria than 3D dose calculations. Conclusions: These results indicate no significant differences in the accuracy between the 4D and the 3D dose

  7. Dose discrepancies in the buildup region and their impact on dose calculations for IMRT fields

    SciTech Connect

    Hsu, Shu-Hui; Moran, Jean M.; Chen Yu; Kulasekere, Ravi; Roberson, Peter L.

    2010-05-15

    Purpose: Dose accuracy in the buildup region for radiotherapy treatment planning suffers from challenges in both measurement and calculation. This study investigates the dosimetry in the buildup region at normal and oblique incidences for open and IMRT fields and assesses the quality of the treatment planning calculations. Methods: This study was divided into three parts. First, percent depth doses and profiles (for 5x5, 10x10, 20x20, and 30x30 cm{sup 2} field sizes at 0 deg., 45 deg., and 70 deg. incidences) were measured in the buildup region in Solid Water using an Attix parallel plate chamber and Kodak XV film, respectively. Second, the parameters in the empirical contamination (EC) term of the convolution/superposition (CVSP) calculation algorithm were fitted based on open field measurements. Finally, seven segmental head-and-neck IMRT fields were measured on a flat phantom geometry and compared to calculations using {gamma} and dose-gradient compensation (C) indices to evaluate the impact of residual discrepancies and to assess the adequacy of the contamination term for IMRT fields. Results: Local deviations between measurements and calculations for open fields were within 1% and 4% in the buildup region for normal and oblique incidences, respectively. The C index with 5%/1 mm criteria for IMRT fields ranged from 89% to 99% and from 96% to 98% at 2 mm and 10 cm depths, respectively. The quality of agreement in the buildup region for open and IMRT fields is comparable to that in nonbuildup regions. Conclusions: The added EC term in CVSP was determined to be adequate for both open and IMRT fields. Due to the dependence of calculation accuracy on (1) EC modeling, (2) internal convolution and density grid sizes, (3) implementation details in the algorithm, and (4) the accuracy of measurements used for treatment planning system commissioning, the authors recommend an evaluation of the accuracy of near-surface dose calculations as a part of treatment planning

  8. Source term calculations for assessing radiation dose to equipment

    SciTech Connect

    Denning, R.S.; Freeman-Kelly, R.; Cybulskis, P.; Curtis, L.A.

    1989-07-01

    This study examines results of analyses performed with the Source Term Code Package to develop updated source terms using NUREG-0956 methods. The updated source terms are to be used to assess the adequacy of current regulatory source terms used as the basis for equipment qualification. Time-dependent locational distributions of radionuclides within a containment following a severe accident have been developed. The Surry reactor has been selected in this study as representative of PWR containment designs. Similarly, the Peach Bottom reactor has been used to examine radionuclide distributions in boiling water reactors. The time-dependent inventory of each key radionuclide is provided in terms of its activity in curies. The data are to be used by Sandia National Laboratories to perform shielding analyses to estimate radiation dose to equipment in each containment design. See NUREG/CR-5175, Beta and Gamma Dose Calculations for PWR and BWR Containments.'' 6 refs., 11 tabs.

  9. New calculations of neutron kerma coefficients and dose equivalent.

    PubMed

    Liu, Zhenzhou; Chen, Jinxiang

    2008-06-01

    For neutron energies ranging from 1 keV to 20 MeV, the kerma coefficients for elements H, C, N, O, light water, and ICRU tissue were deduced respectively from microscopic cross sections and Monte Carlo simulation (MCNP code). The results are consistent within admitted uncertainties with values evaluated by an international group (Chadwick et al 1999 Med. Phys. 26 974-91). The ambient dose equivalent generated in the ISO-recommended neutron field for an Am-Be neutron source (ISO 8529-1: 2001(E)) was obtained from the kerma coefficients and Monte Carlo calculation. In addition, it was calculated directly by multiplying the neutron fluence by the fluence-to-ambient dose conversion coefficients recommended by ICRP (ICRP 1996 ICRP Publication 74 (Oxford: Pergamon)). The two results agree well with each other. The main feature of this work is our Monte Carlo simulation design and the treatments differing from the work of others in the calculation of neutron energy transfer in non-elastic processes. PMID:18495982

  10. Monte Carlo Code System for Electron (Positron) Dose Kernel Calculations.

    1999-05-12

    Version 00 KERNEL performs dose kernel calculations for an electron (positron) isotropic point source in an infinite homogeneous medium. First, the auxiliary code PRELIM is used to prepare cross section data for the considered medium. Then the KERNEL code simulates the transport of electrons and bremsstrahlung photons through the medium until all particles reach their cutoff energies. The deposited energy is scored in concentric spherical shells at a radial distance ranging from zero to twicemore » the source particle range.« less

  11. Calculation of effective doses for broad parallel photon beams.

    PubMed

    Kim, C H; Reece, W D; Poston, J W

    1999-02-01

    Values of effective dose (E) were calculated for the entire range of incident directions of broad parallel photon beams for selected photon energies using the Monte Carlo N-Particle (MCNP) transport code with a hermaphroditic phantom. The calculated results are presented in terms of conversion coefficients transforming air kerma to effective dose. This study also compared the numerical values of E and H(E) over the entire range of incident beam directions. E was always less than H(E) considering all beam directions and photon energies, but the differences were not significant except when a photon beam approaches some specific directions (overhead and underfoot). This result suggests that the current H(E) values can be directly interpreted as E or, at least, as a conservative value of E without knowing the details of irradiation geometries. Finally, based on the distributions of H(E) and E over the beam directions, this study proposes ideal angular response factors for personal dosimeters that can be used to improve the angular response properties of personal dosimeters for off-normal incident photons. PMID:9929126

  12. Assessing the effect of electron density in photon dose calculations

    SciTech Connect

    Seco, J.; Evans, P. M.

    2006-02-15

    Photon dose calculation algorithms (such as the pencil beam and collapsed cone, CC) model the attenuation of a primary photon beam in media other than water, by using pathlength scaling based on the relative mass density of the media to water. In this study, we assess if differences in the electron density between the water and media, with different atomic composition, can influence the accuracy of conventional photon dose calculations algorithms. A comparison is performed between an electron-density scaling method and the standard mass-density scaling method for (i) tissues present in the human body (such as bone, muscle, etc.), and for (ii) water-equivalent plastics, used in radiotherapy dosimetry and quality assurance. We demonstrate that the important material property that should be taken into account by photon dose algorithms is the electron density, and not the mass density. The mass-density scaling method is shown to overestimate, relative to electron-density predictions, the primary photon fluence for tissues in the human body and water-equivalent plastics, where 6%-7% and 10% differences were observed respectively for bone and air. However, in the case of patients, differences are expected to be smaller due to the large complexity of a treatment plan and of the patient anatomy and atomic composition and of the smaller thickness of bone/air that incident photon beams of a treatment plan may have to traverse. Differences have also been observed for conventional dose algorithms, such as CC, where an overestimate of the lung dose occurs, when irradiating lung tumors. The incorrect lung dose can be attributed to the incorrect modeling of the photon beam attenuation through the rib cage (thickness of 2-3 cm in bone upstream of the lung tumor) and through the lung and the oversimplified modeling of electron transport in convolution algorithms. In the present study, the overestimation of the primary photon fluence, using the mass-density scaling method, was shown

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

    SciTech Connect

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

    1981-04-01

    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 mode are also printed if requested.

  14. Independent calculation-based verification of IMRT plans using a 3D dose-calculation engine

    SciTech Connect

    Arumugam, Sankar; Xing, Aitang; Goozee, Gary; Holloway, Lois

    2013-01-01

    Independent monitor unit verification of intensity-modulated radiation therapy (IMRT) plans requires detailed 3-dimensional (3D) dose verification. The aim of this study was to investigate using a 3D dose engine in a second commercial treatment planning system (TPS) for this task, facilitated by in-house software. Our department has XiO and Pinnacle TPSs, both with IMRT planning capability and modeled for an Elekta-Synergy 6 MV photon beam. These systems allow the transfer of computed tomography (CT) data and RT structures between them but do not allow IMRT plans to be transferred. To provide this connectivity, an in-house computer programme was developed to convert radiation therapy prescription (RTP) files as generated by many planning systems into either XiO or Pinnacle IMRT file formats. Utilization of the technique and software was assessed by transferring 14 IMRT plans from XiO and Pinnacle onto the other system and performing 3D dose verification. The accuracy of the conversion process was checked by comparing the 3D dose matrices and dose volume histograms (DVHs) of structures for the recalculated plan on the same system. The developed software successfully transferred IMRT plans generated by 1 planning system into the other. Comparison of planning target volume (TV) DVHs for the original and recalculated plans showed good agreement; a maximum difference of 2% in mean dose, − 2.5% in D95, and 2.9% in V95 was observed. Similarly, a DVH comparison of organs at risk showed a maximum difference of +7.7% between the original and recalculated plans for structures in both high- and medium-dose regions. However, for structures in low-dose regions (less than 15% of prescription dose) a difference in mean dose up to +21.1% was observed between XiO and Pinnacle calculations. A dose matrix comparison of original and recalculated plans in XiO and Pinnacle TPSs was performed using gamma analysis with 3%/3 mm criteria. The mean and standard deviation of pixels passing

  15. Independent calculation-based verification of IMRT plans using a 3D dose-calculation engine.

    PubMed

    Arumugam, Sankar; Xing, Aitang; Goozee, Gary; Holloway, Lois

    2013-01-01

    Independent monitor unit verification of intensity-modulated radiation therapy (IMRT) plans requires detailed 3-dimensional (3D) dose verification. The aim of this study was to investigate using a 3D dose engine in a second commercial treatment planning system (TPS) for this task, facilitated by in-house software. Our department has XiO and Pinnacle TPSs, both with IMRT planning capability and modeled for an Elekta-Synergy 6MV photon beam. These systems allow the transfer of computed tomography (CT) data and RT structures between them but do not allow IMRT plans to be transferred. To provide this connectivity, an in-house computer programme was developed to convert radiation therapy prescription (RTP) files as generated by many planning systems into either XiO or Pinnacle IMRT file formats. Utilization of the technique and software was assessed by transferring 14 IMRT plans from XiO and Pinnacle onto the other system and performing 3D dose verification. The accuracy of the conversion process was checked by comparing the 3D dose matrices and dose volume histograms (DVHs) of structures for the recalculated plan on the same system. The developed software successfully transferred IMRT plans generated by 1 planning system into the other. Comparison of planning target volume (TV) DVHs for the original and recalculated plans showed good agreement; a maximum difference of 2% in mean dose, - 2.5% in D95, and 2.9% in V95 was observed. Similarly, a DVH comparison of organs at risk showed a maximum difference of +7.7% between the original and recalculated plans for structures in both high- and medium-dose regions. However, for structures in low-dose regions (less than 15% of prescription dose) a difference in mean dose up to +21.1% was observed between XiO and Pinnacle calculations. A dose matrix comparison of original and recalculated plans in XiO and Pinnacle TPSs was performed using gamma analysis with 3%/3mm criteria. The mean and standard deviation of pixels passing gamma

  16. Calculation of the absorbed dose and dose equivalent induced by medium energy neutrons and protons and comparison with experiment

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Bishop, B. L.

    1972-01-01

    Monte Carlo calculations have been carried out to determine the absorbed dose and dose equivalent for 592-MeV protons incident on a cylindrical phantom and for neutrons from 580-MeV proton-Be collisions incident on a semi-infinite phantom. For both configurations, the calculated depth dependence of the absorbed dose is in good agreement with experimental data.

  17. Limitations of the TG-43 formalism for skin high-dose-rate brachytherapy dose calculations

    SciTech Connect

    Granero, Domingo; Perez-Calatayud, Jose; Vijande, Javier; Ballester, Facundo; Rivard, Mark J.

    2014-02-15

    Purpose: In skin high-dose-rate (HDR) brachytherapy, sources are located outside, in contact with, or implanted at some depth below the skin surface. Most treatment planning systems use the TG-43 formalism, which is based on single-source dose superposition within an infinite water medium without accounting for the true geometry in which conditions for scattered radiation are altered by the presence of air. The purpose of this study is to evaluate the dosimetric limitations of the TG-43 formalism in HDR skin brachytherapy and the potential clinical impact. Methods: Dose rate distributions of typical configurations used in skin brachytherapy were obtained: a 5 cm × 5 cm superficial mould; a source inside a catheter located at the skin surface with and without backscatter bolus; and a typical interstitial implant consisting of an HDR source in a catheter located at a depth of 0.5 cm. Commercially available HDR{sup 60}Co and {sup 192}Ir sources and a hypothetical {sup 169}Yb source were considered. The Geant4 Monte Carlo radiation transport code was used to estimate dose rate distributions for the configurations considered. These results were then compared to those obtained with the TG-43 dose calculation formalism. In particular, the influence of adding bolus material over the implant was studied. Results: For a 5 cm × 5 cm{sup 192}Ir superficial mould and 0.5 cm prescription depth, dose differences in comparison to the TG-43 method were about −3%. When the source was positioned at the skin surface, dose differences were smaller than −1% for {sup 60}Co and {sup 192}Ir, yet −3% for {sup 169}Yb. For the interstitial implant, dose differences at the skin surface were −7% for {sup 60}Co, −0.6% for {sup 192}Ir, and −2.5% for {sup 169}Yb. Conclusions: This study indicates the following: (i) for the superficial mould, no bolus is needed; (ii) when the source is in contact with the skin surface, no bolus is needed for either {sup 60}Co and {sup 192}Ir. For

  18. Monte Carlo calculation of helical tomotherapy dose delivery

    SciTech Connect

    Zhao Yingli; Mackenzie, M.; Kirkby, C.; Fallone, B. G.

    2008-08-15

    Helical tomotherapy delivers intensity modulated radiation therapy using a binary multileaf collimator (MLC) to modulate a fan beam of radiation. This delivery occurs while the linac gantry and treatment couch are both in constant motion, so the beam describes, from a patient/phantom perspective, a spiral or helix of dose. The planning system models this continuous delivery as a large number (51) of discrete gantry positions per rotation, and given the small jaw/fan width setting typically used (1 or 2.5 cm) and the number of overlapping rotations used to cover the target (pitch often <0.5), the treatment planning system (TPS) potentially employs a very large number of static beam directions and leaf opening configurations to model the modulated fields. All dose calculations performed by the system employ a convolution/superposition model. In this work the authors perform a full Monte Carlo (MC) dose calculation of tomotherapy deliveries to phantom computed tomography (CT) data sets to verify the TPS calculations. All MC calculations are performed with the EGSnrc-based MC simulation codes, BEAMnrc and DOSXYZnrc. Simulations are performed by taking the sinogram (leaf opening versus time) of the treatment plan and decomposing it into 51 different projections per rotation, as does the TPS, each of which is segmented further into multiple MLC opening configurations, each with different weights that correspond to leaf opening times. Then the projection is simulated by the summing of all of the opening configurations, and the overall rotational treatment is simulated by the summing of all of the projection simulations. Commissioning of the source model was verified by comparing measured and simulated values for the percent depth dose and beam profiles shapes for various jaw settings. The accuracy of the MLC leaf width and tongue and groove spacing were verified by comparing measured and simulated values for the MLC leakage and a picket fence pattern. The validated source

  19. Emergency Doses (ED) - Revision 3: A calculator code for environmental dose computations

    SciTech Connect

    Rittmann, P.D.

    1990-12-01

    The calculator program ED (Emergency Doses) was developed from several HP-41CV calculator programs documented in the report Seven Health Physics Calculator Programs for the HP-41CV, RHO-HS-ST-5P (Rittman 1984). The program was developed to enable estimates of offsite impacts more rapidly and reliably than was possible with the software available for emergency response at that time. The ED - Revision 3, documented in this report, revises the inhalation dose model to match that of ICRP 30, and adds the simple estimates for air concentration downwind from a chemical release. In addition, the method for calculating the Pasquill dispersion parameters was revised to match the GENII code within the limitations of a hand-held calculator (e.g., plume rise and building wake effects are not included). The summary report generator for printed output, which had been present in the code from the original version, was eliminated in Revision 3 to make room for the dispersion model, the chemical release portion, and the methods of looping back to an input menu until there is no further no change. This program runs on the Hewlett-Packard programmable calculators known as the HP-41CV and the HP-41CX. The documentation for ED - Revision 3 includes a guide for users, sample problems, detailed verification tests and results, model descriptions, code description (with program listing), and independent peer review. This software is intended to be used by individuals with some training in the use of air transport models. There are some user inputs that require intelligent application of the model to the actual conditions of the accident. The results calculated using ED - Revision 3 are only correct to the extent allowed by the mathematical models. 9 refs., 36 tabs.

  20. Monte Carlo prompt dose calculations for the National Ingition Facility

    SciTech Connect

    Latkowski, J.F.; Phillips, T.W.

    1997-01-01

    During peak operation, the National Ignition Facility (NIF) will conduct as many as 600 experiments per year and attain deuterium- tritium fusion yields as high as 1200 MJ/yr. The radiation effective dose equivalent (EDE) to workers is limited to an average of 03 mSv/yr (30 mrem/yr) in occupied areas of the facility. Laboratory personnel determined located outside the facility will receive EDEs <= 0.5 mSv/yr (<= 50 mrem/yr). The total annual occupational EDE for the facility will be maintained at <= 0.1 person-Sv/yr (<= 10 person- rem/yr). To ensure that prompt EDEs meet these limits, three- dimensional Monte Carlo calculations have been completed.

  1. Absolute dose calculations for Monte Carlo simulations of radiotherapy beams.

    PubMed

    Popescu, I A; Shaw, C P; Zavgorodni, S F; Beckham, W A

    2005-07-21

    Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 x 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 x 10(13) +/- 1.0% electrons incident on the target and a total dose of 20.87 cGy +/- 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations. PMID:16177516

  2. Absolute dose calculations for Monte Carlo simulations of radiotherapy beams

    NASA Astrophysics Data System (ADS)

    Popescu, I. A.; Shaw, C. P.; Zavgorodni, S. F.; Beckham, W. A.

    2005-07-01

    Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 × 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 × 1013 ± 1.0% electrons incident on the target and a total dose of 20.87 cGy ± 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations.

  3. Considerations of beta and electron transport in internal dose calculations

    SciTech Connect

    Bolch, W.E.; Poston, J.W. Sr. . Dept. of Nuclear Engineering)

    1990-12-01

    Ionizing radiation has broad uses in modern science and medicine. These uses often require the calculation of energy deposition in the irradiated media and, usually, the medium of interest is the human body. Energy deposition from radioactive sources within the human body and the effects of such deposition are considered in the field of internal dosimetry. In July of 1988, a three-year research project was initiated by the Nuclear Engineering Department at Texas A M University under the sponsorship of the US Department of Energy. The main thrust of the research was to consider, for the first time, the detailed spatial transport of electron and beta particles in the estimation of average organ doses under the Medical Internal Radiation Dose (MIRD) schema. At the present time (December of 1990), research activities are continuing within five areas. Several are new initiatives begun within the second or third year of the current contract period. They include: (1) development of small-scale dosimetry; (2) development of a differential volume phantom; (3) development of a dosimetric bone model; (4) assessment of the new ICRP lung model; and (5) studies into the mechanisms of DNA damage. A progress report is given for each of these tasks within the Comprehensive Report. In each use, preliminary results are very encouraging and plans for further research are detailed within this document. 22 refs., 13 figs., 1 tab.

  4. Considerations of beta and electron transport in internal dose calculations

    SciTech Connect

    Bolch, W.E.; Poston, J.W. Sr.

    1990-12-01

    Ionizing radiation has broad uses in modern science and medicine. These uses often require the calculation of energy deposition in the irradiated media and, usually, the medium of interest is the human body. Energy deposition from radioactive sources within the human body and the effects of such deposition are considered in the field of internal dosimetry. In July of 1988, a three-year research project was initiated by the Nuclear Engineering Department at Texas A M University under the sponsorship of the US Department of Energy. The main thrust of the research was to consider, for the first time, the detailed spatial transport of electron and beta particles in the estimation of average organ doses under the Medical Internal Radiation Dose (MIRD) schema. At the present time (December of 1990), research activities are continuing within five areas. Several are new initiatives begun within the second or third year of the current contract period. They include: (1) development of small-scale dosimetry; (2) development of a differential volume phantom; (3) development of a dosimetric bone model; (4) assessment of the new ICRP lung model; and (5) studies into the mechanisms of DNA damage. A progress report is given for each of these tasks within the Comprehensive Report. In each case, preliminary results are very encouraging and plans for further research are detailed within this document.

  5. Dose Distribution Calculation in Skin Cancer Treatment Using Leipzig Applicator

    NASA Astrophysics Data System (ADS)

    Mowlawi, Ali Asghar; Yazdani, Majed

    The combination of 192Ir seed with the Leipzig applicators is used in a considerable number of clinical trials for skin cancer treatment. As is known, the beneficial effects of ionizing radiation for tumor treatment depends on the dosimetry accuracy. Nowadays, dosimetry calculations are supported by the characteristics provided by the manufacturer, which have been obtained from measurements with an ionization chamber in a phantom. Despite their benefit, the experimental data involves errors related to the positioning, energy, and angular dependence of the detectors. Thus, in order to get a detailed and more accurate dosimetry, the Monte Carlo code MCNP4C2 — Monte Carlo Neutron Particle, 4C2 version — has been employed to analyze the dose distribution in depth and at the surface in the skin cancer treatment using Leipzig applicators. On the other hand, some different measurements have been taken to validate the method and compare results. The results for this material of phantom (the skin with 0.5 cm thick over infinite soft tissue) can be used in treatment planning systems and also for computation of model dependent parameters like anisotropy dose function.

  6. Comparisons of TORT and MCNP dose calculations for BNCT treatment planning

    SciTech Connect

    Ingersol, D.T.; Slater, C.O.; Williams, L.R.; Redmond, E.L., II; Zamenhof, R.G.

    1996-12-31

    The relative merit of using a deterministic code to calculate dose distributions for BNCT applications were examined. The TORT discrete deterministic ordinated code was used in comparison to MCNP4A to calculate dose distributions for BNCT applications

  7. A simple dose calculation method for total body photon irradiation

    SciTech Connect

    Curran, W.J. Jr.; Galvin, J.M.; D'Angio, G.J.

    1989-07-01

    A simple technique for calculation of the prescribed dose for total body irradiation (TBI) is presented. The technique uses a standard calibration procedure and applies standard correction methods to account for variations in the field size, depth, and treatment distance. Since the scattering volume (the entire body) is smaller than the X ray field for this treatment, the change in output with field size is handled separately from changes due to scatter within the phantom. The latter is shown to be a function of the phantom size (corresponding to the frontal area of the trunk of the body for patient irradiation) rather than the size of the field opening. Dosimetric tests of this technique have been conducted and the errors determined. For these tests, three different phantom sizes were used to represent the upper body sizes of a 2-year old child, an 8-year old, and an adult, and three linear accelerator energies (6, 10, and 15 MV) were included. Calculations were performed using the technique and compared to measurements for the same phantom sizes. Differences of less than 1.3 were found.

  8. 78 FR 64030 - Monitoring Criteria and Methods To Calculate Occupational Radiation Doses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-25

    ... monitoring and calculating occupational radiation doses. On December 4, 2007 (72 FR 68043), the NRC revised... COMMISSION Monitoring Criteria and Methods To Calculate Occupational Radiation Doses AGENCY: Nuclear... Criteria and Methods to Calculate Occupational Radiation Doses.'' This guide describes methods that the...

  9. Clinical implementation of the Peregrine Monte Carlo dose calculations system for photon beam therapy

    SciTech Connect

    Albright, N; Bergstrom, P M; Daly, T P; Descalle, M; Garrett, D; House, R K; Knapp, D K; May, S; Patterson, R W; Siantar, C L; Verhey, L; Walling, R S; Welczorek, D

    1999-07-01

    PEREGRINE is a 3D Monte Carlo dose calculation system designed to serve as a dose calculation engine for clinical radiation therapy treatment planning systems. Taking advantage of recent advances in low-cost computer hardware, modern multiprocessor architectures and optimized Monte Carlo transport algorithms, PEREGRINE performs mm-resolution Monte Carlo calculations in times that are reasonable for clinical use. PEREGRINE has been developed to simulate radiation therapy for several source types, including photons, electrons, neutrons and protons, for both teletherapy and brachytherapy. However the work described in this paper is limited to linear accelerator-based megavoltage photon therapy. Here we assess the accuracy, reliability, and added value of 3D Monte Carlo transport for photon therapy treatment planning. Comparisons with clinical measurements in homogeneous and heterogeneous phantoms demonstrate PEREGRINE's accuracy. Studies with variable tissue composition demonstrate the importance of material assignment on the overall dose distribution. Detailed analysis of Monte Carlo results provides new information for radiation research by expanding the set of observables.

  10. Efficient and reliable 3D dose quality assurance for IMRT by combining independent dose calculations with measurements

    SciTech Connect

    Visser, R.; Wauben, D. J. L.; Godart, J.; Langendijk, J. A.; Veld, A. A. van't; Korevaar, E. W.; Groot, M. de

    2013-02-15

    Purpose: Advanced radiotherapy treatments require appropriate quality assurance (QA) to verify 3D dose distributions. Moreover, increase in patient numbers demand efficient QA-methods. In this study, a time efficient method that combines model-based QA and measurement-based QA was developed; i.e., the hybrid-QA. The purpose of this study was to determine the reliability of the model-based QA and to evaluate time efficiency of the hybrid-QA method. Methods: Accuracy of the model-based QA was determined by comparison of COMPASS calculated dose with Monte Carlo calculations for heterogeneous media. In total, 330 intensity modulated radiation therapy (IMRT) treatment plans were evaluated based on the mean gamma index (GI) with criteria of 3%/3mm and classification of PASS (GI {<=} 0.4), EVAL (0.4 < GI > 0.6), and FAIL (GI {>=} 0.6). Agreement between model-based QA and measurement-based QA was determined for 48 treatment plans, and linac stability was verified for 15 months. Finally, time efficiency improvement of the hybrid-QA was quantified for four representative treatment plans. Results: COMPASS calculated dose was in agreement with Monte Carlo dose, with a maximum error of 3.2% in heterogeneous media with high density (2.4 g/cm{sup 3}). Hybrid-QA results for IMRT treatment plans showed an excellent PASS rate of 98% for all cases. Model-based QA was in agreement with measurement-based QA, as shown by a minimal difference in GI of 0.03 {+-} 0.08. Linac stability was high with an average GI of 0.28 {+-} 0.04. The hybrid-QA method resulted in a time efficiency improvement of 15 min per treatment plan QA compared to measurement-based QA. Conclusions: The hybrid-QA method is adequate for efficient and accurate 3D dose verification. It combines time efficiency of model-based QA with reliability of measurement-based QA and is suitable for implementation within any radiotherapy department.

  11. BENCHMARKING UPGRADED HOTSPOT DOSE CALCULATIONS AGAINST MACCS2 RESULTS

    SciTech Connect

    Brotherton, Kevin

    2009-04-30

    The radiological consequence of interest for a documented safety analysis (DSA) is the centerline Total Effective Dose Equivalent (TEDE) incurred by the Maximally Exposed Offsite Individual (MOI) evaluated at the 95th percentile consequence level. An upgraded version of HotSpot (Version 2.07) has been developed with the capabilities to read site meteorological data and perform the necessary statistical calculations to determine the 95th percentile consequence result. These capabilities should allow HotSpot to join MACCS2 (Version 1.13.1) and GENII (Version 1.485) as radiological consequence toolbox codes in the Department of Energy (DOE) Safety Software Central Registry. Using the same meteorological data file, scenarios involving a one curie release of {sup 239}Pu were modeled in both HotSpot and MACCS2. Several sets of release conditions were modeled, and the results compared. In each case, input parameter specifications for each code were chosen to match one another as much as the codes would allow. The results from the two codes are in excellent agreement. Slight differences observed in results are explained by algorithm differences.

  12. Dose calculation accuracies in whole breast radiotherapy treatment planning: a multi-institutional study.

    PubMed

    Hatanaka, Shogo; Miyabe, Yuki; Tohyama, Naoki; Kumazaki, Yu; Kurooka, Masahiko; Okamoto, Hiroyuki; Tachibana, Hidenobu; Kito, Satoshi; Wakita, Akihisa; Ohotomo, Yuko; Ikagawa, Hiroyuki; Ishikura, Satoshi; Nozaki, Miwako; Kagami, Yoshikazu; Hiraoka, Masahiro; Nishio, Teiji

    2015-07-01

    Our objective in this study was to evaluate the variation in the doses delivered among institutions due to dose calculation inaccuracies in whole breast radiotherapy. We have developed practical procedures for quality assurance (QA) of radiation treatment planning systems. These QA procedures are designed to be performed easily at any institution and to permit comparisons of results across institutions. The dose calculation accuracy was evaluated across seven institutions using various irradiation conditions. In some conditions, there was a >3 % difference between the calculated dose and the measured dose. The dose calculation accuracy differs among institutions because it is dependent on both the dose calculation algorithm and beam modeling. The QA procedures in this study are useful for verifying the accuracy of the dose calculation algorithm and of the beam model before clinical use for whole breast radiotherapy. PMID:25646770

  13. Dose Rate Calculation of TRU Metal Ingot in Pyroprocessing - 12202

    SciTech Connect

    Lee, Yoon Hee; Lee, Kunjai

    2012-07-01

    Spent fuel management has been a main problem to be solved for continuous utilization of nuclear energy. Spent fuel management policy of Korea is 'Wait and See'. It is focused on Pyro-process and SFR (Sodium-cooled Fast Reactor) for closed-fuel cycle research and development in Korea. For peaceful use of nuclear facilities, the proliferation resistance has to be proved. Proliferation resistance is one of key constraints in the deployment of advanced nuclear energy systems. Non-proliferation and safeguard issues have been strengthening internationally. Barriers to proliferation are that reduces desirability or attractiveness as an explosive and makes it difficult to gain access to the materials, or makes it difficult to misuse facilities and/or technologies for weapons applications. Barriers to proliferation are classified into intrinsic and extrinsic barriers. Intrinsic barrier is inherent quality of reactor materials or the fuel cycle that is built into the reactor design and operation such as material and technical barriers. As one of the intrinsic measures, the radiation from the material is considered significantly. Therefore the radiation of TRU metal ingot from the pyro-process was calculated using ORIGEN and MCNP code. (authors)

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

    SciTech Connect

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

    2014-06-15

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

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

    SciTech Connect

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

    1980-03-01

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

  16. Low dose dynamic myocardial CT perfusion using advanced iterative reconstruction

    NASA Astrophysics Data System (ADS)

    Eck, Brendan L.; Fahmi, Rachid; Fuqua, Christopher; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

    2015-03-01

    Dynamic myocardial CT perfusion (CTP) can provide quantitative functional information for the assessment of coronary artery disease. However, x-ray dose in dynamic CTP is high, typically from 10mSv to >20mSv. We compared the dose reduction potential of advanced iterative reconstruction, Iterative Model Reconstruction (IMR, Philips Healthcare, Cleveland, Ohio) to hybrid iterative reconstruction (iDose4) and filtered back projection (FBP). Dynamic CTP scans were obtained using a porcine model with balloon-induced ischemia in the left anterior descending coronary artery to prescribed fractional flow reserve values. High dose dynamic CTP scans were acquired at 100kVp/100mAs with effective dose of 23mSv. Low dose scans at 75mAs, 50mAs, and 25mAs were simulated by adding x-ray quantum noise and detector electronic noise to the projection space data. Images were reconstructed with FBP, iDose4, and IMR at each dose level. Image quality in static CTP images was assessed by SNR and CNR. Blood flow was obtained using a dynamic CTP analysis pipeline and blood flow image quality was assessed using flow-SNR and flow-CNR. IMR showed highest static image quality according to SNR and CNR. Blood flow in FBP was increasingly over-estimated at reduced dose. Flow was more consistent for iDose4 from 100mAs to 50mAs, but was over-estimated at 25mAs. IMR was most consistent from 100mAs to 25mAs. Static images and flow maps for 100mAs FBP, 50mAs iDose4, and 25mAs IMR showed comparable, clear ischemia, CNR, and flow-CNR values. These results suggest that IMR can enable dynamic CTP at significantly reduced dose, at 5.8mSv or 25% of the comparable 23mSv FBP protocol.

  17. Scoping calculation for components of the cow-milk dose pathway for evaluating the dose contribution from iodine-131. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities

    SciTech Connect

    Ikenberry, T.A.; Napier, B.A.

    1992-12-01

    A series of scoping calculations have been undertaken to evaluate The absolute and relative contribution of different exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 001) examined the contributions of the various exposure pathways associated with environmental transport and accumulation of iodine-131 in the pasture-cow-milk pathway. Addressed in this calculation were the contributions to thyroid dose of infants and adult from (1) the ingestion by dairy cattle of various feedstuffs (pasturage, silage, alfalfa hay, and grass hay) in four different feeding regimes; (2) ingestion of soil by dairy cattle; (3) ingestion of stared feed on which airborne iodine-131 had been deposited; and (4) inhalation of airborne iodine-131 by dairy cows.

  18. Generation and use of measurement-based 3-D dose distributions for 3-D dose calculation verification.

    PubMed

    Stern, R L; Fraass, B A; Gerhardsson, A; McShan, D L; Lam, K L

    1992-01-01

    A 3-D radiation therapy treatment planning system calculates dose to an entire volume of points and therefore requires a 3-D distribution of measured dose values for quality assurance and dose calculation verification. To measure such a volumetric distribution with a scanning ion chamber is prohibitively time consuming. A method is presented for the generation of a 3-D grid of dose values based on beam's-eye-view (BEV) film dosimetry. For each field configuration of interest, a set of BEV films at different depths is obtained and digitized, and the optical densities are converted to dose. To reduce inaccuracies associated with film measurement of megavoltage photon depth doses, doses on the different planes are normalized using an ion-chamber measurement of the depth dose. A 3-D grid of dose values is created by interpolation between BEV planes along divergent beam rays. This matrix of measurement-based dose values can then be compared to calculations over the entire volume of interest. This method is demonstrated for three different field configurations. Accuracy of the film-measured dose values is determined by 1-D and 2-D comparisons with ion chamber measurements. Film and ion chamber measurements agree within 2% in the central field regions and within 2.0 mm in the penumbral regions. PMID:1620042

  19. Hanford Site Annual Report Radiological Dose Calculation Upgrade Evaluation

    SciTech Connect

    Snyder, Sandra F.

    2010-02-28

    Operations at the Hanford Site, Richland, Washington, result in the release of radioactive materials to offsite residents. Site authorities are required to estimate the dose to the maximally exposed offsite resident. Due to the very low levels of exposure at the residence, computer models, rather than environmental samples, are used to estimate exposure, intake, and dose. A DOS-based model has been used in the past (GENII version 1.485). GENII v1.485 has been updated to a Windows®-based software (GENII version 2.08). Use of the updated software will facilitate future dose evaluations, but must be demonstrated to provide results comparable to those of GENII v1.485. This report describes the GENII v1.485 and GENII v2.08 dose exposure, intake, and dose estimates for the maximally exposed offsite resident reported for calendar year 2008. The GENII v2.08 results reflect updates to implemented algorithms. No two environmental models produce the same results, as was again demonstrated in this report. The aggregated dose results from 2008 Hanford Site airborne and surface water exposure scenarios provide comparable dose results. Therefore, the GENII v2.08 software is recommended for future offsite resident dose evaluations.

  20. Analysis of offsite dose calculation methodology for a nuclear power reactor

    SciTech Connect

    Moser, D.M.

    1995-12-31

    This technical study reviews the methodology for calculating offsite dose estimates as described in the offsite dose calculation manual (ODCM) for Pennsylvania Power and Light - Susquehanna Steam Electric Station (SSES). An evaluation of the SSES ODCM dose assessment methodology indicates that it conforms with methodology accepted by the US Nuclear Regulatory Commission (NRC). Using 1993 SSES effluent data, dose estimates are calculated according to SSES ODCM methodology and compared to the dose estimates calculated according to SSES ODCM and the computer model used to produce the reported 1993 dose estimates. The 1993 SSES dose estimates are based on the axioms of Publication 2 of the International Commission of Radiological Protection (ICRP). SSES Dose estimates based on the axioms of ICRP Publication 26 and 30 reveal the total body estimates to be the most affected.

  1. Cone-Beam Computed Tomography: Imaging Dose during CBCT Scan Acquisition and Accuracy of CBCT Based Dose Calculations

    NASA Astrophysics Data System (ADS)

    Giles, David Matthew

    Cone beam computed tomography (CBCT) is a recent development in radiotherapy for use in image guidance. Image guided radiotherapy using CBCT allows visualization of soft tissue targets and critical structures prior to treatment. Dose escalation is made possible by accurately localizing the target volume while reducing normal tissue toxicity. The kilovoltage x-rays of the cone beam imaging system contribute additional dose to the patient. In this study a 2D reference radiochromic film dosimetry method employing GAFCHROMIC(TM) model XR-QA film is used to measure point skin doses and dose profiles from the Elekta XVI CBCT system integrated onto the Synergy linac. The soft tissue contrast of the daily CBCT images makes adaptive radiotherapy possible in the clinic. In order to track dose to the patient or utilize on-line replanning for adaptive radiotherapy the CBCT images must be used to calculate dose. A Hounsfield unit calibration method for scatter correction is investigated for heterogeneity corrected dose calculation in CBCT images. Three Hounsfield unit to density calibration tables are used for each of four cases including patients and an anthropomorphic phantom, and the calculated dose from each is compared to results from the clinical standard fan beam CT. The dose from the scan acquisition is reported and the effect of scan geometry and total output of the x-ray tube on dose magnitude and distribution is shown. The ability to calculate dose with CBCT is shown to improve with the use of patient specific density tables for scatter correction, and for high beam energies the calculated dose agreement is within 1%.

  2. Monte Carlo PENRADIO software for dose calculation in medical imaging

    NASA Astrophysics Data System (ADS)

    Adrien, Camille; Lòpez Noriega, Mercedes; Bonniaud, Guillaume; Bordy, Jean-Marc; Le Loirec, Cindy; Poumarede, Bénédicte

    2014-06-01

    The increase on the collective radiation dose due to the large number of medical imaging exams has led the medical physics community to deeply consider the amount of dose delivered and its associated risks in these exams. For this purpose we have developed a Monte Carlo tool, PENRADIO, based on a modified version of PENELOPE code 2006 release, to obtain an accurate individualized radiation dose in conventional and interventional radiography and in computed tomography (CT). This tool has been validated showing excellent agreement between the measured and simulated organ doses in the case of a hip conventional radiography and a coronography. We expect the same accuracy in further results for other localizations and CT examinations.

  3. Three-Dimensional Dose Calculation for Total Body Irradiation

    NASA Astrophysics Data System (ADS)

    Ito, Akira

    Bone Marrow Transplant (BMT) therapy has been a big success in the treatment of leukemia and other haematopoietic diseases 1 . Prior to BMT, total body irradiation (TBI) is given to the patient for the purpose of (1) killing leukemia cells in bone marrow, as well as in the whole body, and (2) producing immuno-suppressive status in the patient so that the donor's marrow cells will be transplanted without rejection. TBI employs a very large field photon beam to irradiate the whole body of the patient. A uniform dose distribution over the entire body is the treatment goal. To prevent the occurrence of a serious side effect (interstitial pneumonia), the lung dose should not exceed a certain level. This novel technique poses various new radiological physics problems. The accurate assessment of dose and dose distribution in the patient is essential. Physical and dosimetric problems associated with TBI are reviewed elsewhere 2,3 .

  4. Integral-transport-based deterministic brachytherapy dose calculations

    NASA Astrophysics Data System (ADS)

    Zhou, Chuanyu; Inanc, Feyzi

    2003-01-01

    We developed a transport-equation-based deterministic algorithm for computing three-dimensional brachytherapy dose distributions. The deterministic algorithm has been based on the integral transport equation. The algorithm provided us with the capability of computing dose distributions for multiple isotropic point and/or volumetric sources in a homogenous/heterogeneous medium. The algorithm results have been benchmarked against the results from the literature and MCNP results for isotropic point sources and volumetric sources.

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

    PubMed

    Rahmani, Faezeh; Shahriari, Majid

    2011-12-01

    In-phantom measurement of physical dose distribution is very important for Boron Neutron Capture Therapy (BNCT) planning validation. If any changes take place in therapeutic neutron beam due to the beam shaping assembly (BSA) change, the dose will be changed so another group of simulations should be carried out for dose calculation. To avoid this time consuming procedure and speed up the dose calculation to help patients not wait for a long time, response matrix method was used. This procedure was performed for neutron beam of the optimized BSA as a reference beam. These calculations were carried out using the MCNPX, Monte Carlo code. The calculated beam parameters were measured for a SNYDER head phantom placed 10 cm away from beam the exit of the BSA. The head phantom can be assumed as a linear system and neutron beam and dose distribution can be assumed as an input and a response of this system (head phantom), respectively. Neutron spectrum energy was digitized into 27 groups. Dose response of each group was calculated. Summation of these dose responses is equal to a total dose of the whole neutron/gamma spectrum. Response matrix is the double dimension matrix (energy/dose) in which each parameter represents a depth-dose resulted from specific energy. If the spectrum is changed, response of each energy group may be differed. By considering response matrix and energy vector, dose response can be calculated. This method was tested for some BSA, and calculations show statistical errors less than 10%. PMID:21450471

  6. Calculation of total effective dose equivalent and collective dose in the event of a LOCA in Bushehr Nuclear Power Plant.

    PubMed

    Raisali, G; Davilu, H; Haghighishad, A; Khodadadi, R; Sabet, M

    2006-01-01

    In this research, total effective dose equivalent (TEDE) and collective dose (CD) are calculated for the most adverse potential accident in Bushehr Nuclear Power Plant from the viewpoint of radionuclides release to the environment. Calculations are performed using a Gaussian diffusion model and a slightly modified version of AIREM computer code to adopt for conditions in Bushehr. The results are comparable with the final safety analysis report which used DOZAM code. Results of our calculations show no excessive dose in populated regions. Maximum TEDE is determined to be in the WSW direction. CD in the area around the nuclear power plant by a distance of 30 km (138 man Sv) is far below the accepted limits. Thyroid equivalent dose is also calculated for the WSW direction (maximum 25.6 mSv) and is below the limits at various distances from the reactor stack. PMID:16785243

  7. Improvements in dose calculation accuracy for small off-axis targets in high dose per fraction tomotherapy

    SciTech Connect

    Hardcastle, Nicholas; Bayliss, Adam; Wong, Jeannie Hsiu Ding; Rosenfeld, Anatoly B.; Tome, Wolfgang A.

    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 receiving 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.

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

    SciTech Connect

    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 projection 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.

  9. Kilovoltage beam Monte Carlo dose calculations in submillimeter voxels for small animal radiotherapy

    PubMed Central

    Bazalova, Magdalena; Zhou, Hu; Keall, Paul J.; Graves, Edward E.

    2009-01-01

    Purpose: Small animal conformal radiotherapy (RT) is essential for preclinical cancer research studies and therefore various microRT systems have been recently designed. The aim of this paper is to efficiently calculate the dose delivered using our microRT system based on a microCT scanner with the Monte Carlo (MC) method and to compare the MC calculations to film measurements. Methods: Doses from 2–30 mm diameter 120 kVp photon beams deposited in a solid water phantom with 0.2×0.2×0.2 mm3 voxels are calculated using the latest versions of the EGSnrc codes BEAMNRC and DOSXYZNRC. Two dose calculation approaches are studied: a two-step approach using phase-space files and direct dose calculation with BEAMNRC simulation sources. Due to the small beam size and submillimeter voxel size resulting in long calculation times, variance reduction techniques are studied. The optimum bremsstrahlung splitting number (NBRSPL in BEAMNRC) and the optimum DOSXYZNRC photon splitting (Nsplit) number are examined for both calculation approaches and various beam sizes. The dose calculation efficiencies and the required number of histories to achieve 1% statistical uncertainty—with no particle recycling—are evaluated for 2–30 mm beams. As a final step, film dose measurements are compared to MC calculated dose distributions. Results: The optimum NBRSPL is approximately 1×106 for both dose calculation approaches. For the dose calculations with phase-space files, Nsplit varies only slightly for 2–30 mm beams and is established to be 300. Nsplit for the DOSXYZNRC calculation with the BEAMNRC source ranges from 300 for the 30 mm beam to 4000 for the 2 mm beam. The calculation time significantly increases for small beam sizes when the BEAMNRC simulation source is used compared to the simulations with phase-space files. For the 2 and 30 mm beams, the dose calculations with phase-space files are more efficient than the dose calculations with BEAMNRC sources by factors of 54 and 1

  10. GPU-accelerated Monte Carlo convolution∕superposition implementation for dose calculation

    PubMed Central

    Zhou, Bo; Yu, Cedric X.; Chen, Danny Z.; Hu, X. Sharon

    2010-01-01

    Purpose: Dose calculation is a key component in radiation treatment planning systems. Its performance and accuracy are crucial to the quality of treatment plans as emerging advanced radiation therapy technologies are exerting ever tighter constraints on dose calculation. A common practice is to choose either a deterministic method such as the convolution∕superposition (CS) method for speed or a Monte Carlo (MC) method for accuracy. The goal of this work is to boost the performance of a hybrid Monte Carlo convolution∕superposition (MCCS) method by devising a graphics processing unit (GPU) implementation so as to make the method practical for day-to-day usage. Methods: Although the MCCS algorithm combines the merits of MC fluence generation and CS fluence transport, it is still not fast enough to be used as a day-to-day planning tool. To alleviate the speed issue of MC algorithms, the authors adopted MCCS as their target method and implemented a GPU-based version. In order to fully utilize the GPU computing power, the MCCS algorithm is modified to match the GPU hardware architecture. The performance of the authors’ GPU-based implementation on an Nvidia GTX260 card is compared to a multithreaded software implementation on a quad-core system. Results: A speedup in the range of 6.7–11.4× is observed for the clinical cases used. The less than 2% statistical fluctuation also indicates that the accuracy of the authors’ GPU-based implementation is in good agreement with the results from the quad-core CPU implementation. Conclusions: This work shows that GPU is a feasible and cost-efficient solution compared to other alternatives such as using cluster machines or field-programmable gate arrays for satisfying the increasing demands on computation speed and accuracy of dose calculation. But there are also inherent limitations of using GPU for accelerating MC-type applications, which are also analyzed in detail in this article. PMID:21158271

  11. Determination of radionuclides and pathways contributing to dose in 1945. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities, Calculation 003

    SciTech Connect

    Napier, B.A.

    1992-12-01

    A series of scoping calculations has been undertaken to evaluate the absolute and relative contributions 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 003) examined the contributions of numerous radionuclides to dose via environmental exposures and accumulation in foods. This study builds on the work initiated in the first scoping study of iodine in cow`s milk (calculation 001). Addressed in this calculation were the contributions to organ and effective dose of infants and adults 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.

  12. Radial Dose Profiles: Calculation Refinements and Sensitivities to Single Event Effects Analysis

    NASA Technical Reports Server (NTRS)

    Patterson, Jeffrey; Swimm, Randall

    2005-01-01

    Comparisons of radial dose calculation are performed, as well as the introduction of important physics to improve the calculation techniques. Also, the consequences to device performance are explored via numerical simulations.

  13. Experimental validation of Monte Carlo calculations for organ dose

    SciTech Connect

    Yalcintas, M.G.; Eckerman, K.F.; Warner, G.G.

    1980-01-01

    The problem of validating estimates of absorbed dose due to photon energy deposition is examined. The computational approaches used for the estimation of the photon energy deposition is examined. The limited data for validation of these approaches is discussed and suggestions made as to how better validation information might be obtained. (ACR)

  14. Calculates External and Inhalation Doses from Acute Radionuclide Releases on the Hanford Site.

    1984-03-02

    HADOC (Hanford Acute Dose Calculations) calculates external and inhalation doses resulting from postulated accidental radionuclide releases on the Hanford site. It generates doses to an individual at a specified location and to the population in the region near the Hanford site for specified organs. Doses reported include the maximally exposed individual's dose (by organ and exposure mode) and the total population dose (by organ and exposure mode) in the sector having the highest population exposuremore » factor. The first year and fifty-year dose commitments are reported. Optional reports giving the fractional contribution to total dose by radionuclide for each organ and dose commitment period for a maximally exposed individual and the population may be printed.« less

  15. Prototype Operational Advances for Atmospheric Radiation Dose Rate Specification

    NASA Astrophysics Data System (ADS)

    Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Garrett, H. B.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, D.; Mertens, C. J.; Xu, X.; Crowley, G.; Reynolds, A.; Azeem, I.; Wiltberger, M. J.; Wiley, S.; Bacon, S.; Teets, E.; Sim, A.; Dominik, L.

    2014-12-01

    effective dose rate measurements and a thermal neutron monitor to characterize Single Event Effects (SEEs) in avionics. In this presentation we describe recent ARMAS and USEWX advances that will ultimately provide operational users with real-time dose and dose rate data for human tissue and avionics exposure risk mitigation.

  16. Specification of absorbed dose to water using model-based dose calculation algorithms for treatment planning in brachytherapy

    NASA Astrophysics Data System (ADS)

    Carlsson Tedgren, Åsa; Alm Carlsson, Gudrun

    2013-04-01

    Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm-10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from 125I, 169Yb and 192Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1-10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies <20 keV. A choice of an appropriate conversion coefficient Dw, med/Dmed is discussed in terms of the cavity size in relation to the size of important cellular targets. Free radicals from DNA bound water of nanometre dimensions contribute to DNA damage and cell killing and may be the most important water compartment in cells implying use of ratios of mass-collision-stopping powers for converting Dmed into Dw,med.

  17. Estimation of Nuclear Reaction Effects in Proton-Tissue-Dose Calculations.

    1983-01-14

    Version 00 REPC reviews calculational methods for the estimation of dose from external proton exposure of arbitrary convex bodies and presents the necessary information for the estimation of dose in soft tissue. The effects of nuclear reactions, especially in relation to the dose equivalent, are retained. REPC subroutines can be used to convert existing computer programs which neglect nuclear reaction effects to include them.

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

    SciTech Connect

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

    1993-03-01

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

  19. Calculation of Radiation Doses from Uranium Recovery Operations.

    1980-12-08

    Version: 00 MILDOS estimates impacts from radioactive emissions from uranium milling facilities. These impacts are presented as dose commitments to individuals and the regional population within an 80 km radius of the facility. Only airborne releases of radioactive materials are considered: releases to surface water and to groundwater are not addressed in MILDOS. This is a multi-purpose code system, within the range of its proper application, and can be used to evaluate population doses formore » NEPA assessments, maximum individual doses for predictive 40 CFR 190 compliance evaluations, or maximum offsite air concentrations for predictive evaluations of 10 CFR 20 compliance. The MILDOS package includes models for both point sources (stacks, vents) and area sources (ore pads, tailings areas). Gaseous releases are limited to consideration of 222Rn plus ingrowth of daughters. Exposure pathways of concern are assumed to be inhalation of airborne radioactive material, ingestion of vegetables, meat, and milk contaminated via deposition, and external exposure to radiation emitted by airborne activity and activity deposited on ground surfaces. Liquid exposure pathways are not treated by MILDOS.« less

  20. Evaluation of a new commercial Monte Carlo dose calculation algorithm for electron beams

    SciTech Connect

    Vandervoort, Eric J. Cygler, Joanna E.; Tchistiakova, Ekaterina; La Russa, Daniel J.

    2014-02-15

    Purpose: In this report the authors present the validation of a Monte Carlo dose calculation algorithm (XiO EMC from Elekta Software) for electron beams. Methods: Calculated and measured dose distributions were compared for homogeneous water phantoms and for a 3D heterogeneous phantom meant to approximate the geometry of a trachea and spine. Comparisons of measurements and calculated data were performed using 2D and 3D gamma index dose comparison metrics. Results: Measured outputs agree with calculated values within estimated uncertainties for standard and extended SSDs for open applicators, and for cutouts, with the exception of the 17 MeV electron beam at extended SSD for cutout sizes smaller than 5 × 5 cm{sup 2}. Good agreement was obtained between calculated and experimental depth dose curves and dose profiles (minimum number of measurements that pass a 2%/2 mm agreement 2D gamma index criteria for any applicator or energy was 97%). Dose calculations in a heterogeneous phantom agree with radiochromic film measurements (>98% of pixels pass a 3 dimensional 3%/2 mm γ-criteria) provided that the steep dose gradient in the depth direction is considered. Conclusions: Clinically acceptable agreement (at the 2%/2 mm level) between the measurements and calculated data for measurements in water are obtained for this dose calculation algorithm. Radiochromic film is a useful tool to evaluate the accuracy of electron MC treatment planning systems in heterogeneous media.

  1. Calculating integral dose using data exported from a commercial record and verify system.

    PubMed

    Fox, C; Hardcastle, N; Lim, A; Khor, R

    2015-06-01

    Integral dose has been useful in investigations into the incidence of second primary malignancies in radiotherapy patients. This note outlines an approach to calculation of integral dose for a group of prostate patients using only data exported from a commercial record and verify system. Even though it was necessary to make some assumptions about patient anatomy, comparison with integral dose calculated from data exported from the planning system showed good agreement. PMID:25869674

  2. Independent absorbed-dose calculation using the Monte Carlo algorithm in volumetric modulated arc therapy

    PubMed Central

    2014-01-01

    Purpose To report the result of independent absorbed-dose calculations based on a Monte Carlo (MC) algorithm in volumetric modulated arc therapy (VMAT) for various treatment sites. Methods and materials All treatment plans were created by the superposition/convolution (SC) algorithm of SmartArc (Pinnacle V9.2, Philips). The beam information was converted into the format of the Monaco V3.3 (Elekta), which uses the X-ray voxel-based MC (XVMC) algorithm. The dose distribution was independently recalculated in the Monaco. The dose for the planning target volume (PTV) and the organ at risk (OAR) were analyzed via comparisons with those of the treatment plan. Before performing an independent absorbed-dose calculation, the validation was conducted via irradiation from 3 different gantry angles with a 10- × 10-cm2 field. For the independent absorbed-dose calculation, 15 patients with cancer (prostate, 5; lung, 5; head and neck, 3; rectal, 1; and esophageal, 1) who were treated with single-arc VMAT were selected. To classify the cause of the dose difference between the Pinnacle and Monaco TPSs, their calculations were also compared with the measurement data. Result In validation, the dose in Pinnacle agreed with that in Monaco within 1.5%. The agreement in VMAT calculations between Pinnacle and Monaco using phantoms was exceptional; at the isocenter, the difference was less than 1.5% for all the patients. For independent absorbed-dose calculations, the agreement was also extremely good. For the mean dose for the PTV in particular, the agreement was within 2.0% in all the patients; specifically, no large difference was observed for high-dose regions. Conversely, a significant difference was observed in the mean dose for the OAR. For patients with prostate cancer, the mean rectal dose calculated in Monaco was significantly smaller than that calculated in Pinnacle. Conclusions There was no remarkable difference between the SC and XVMC calculations in the high-dose regions

  3. RADIATION DOSE CALCULATION FOR FUEL HANDLING FACILITY CLOSURE CELL EQUIPMENT

    SciTech Connect

    D. Musat

    2005-03-07

    This calculation evaluates the energy deposition rates in silicon, gamma and neutron flux spectra at various locations of interest throughout FHF closure cell. The physical configuration features a complex geometry, with particle flux attenuation of many orders of magnitude that cannot be modeled by computer codes that use deterministic methods. Therefore, in this calculation the Monte Carlo method was used to solve the photon and neutron transport. In contrast with the deterministic methods, Monte Carlo does not solve an explicit transport equation, but rather obtain answers by simulating individual particles, recording the aspects of interest of their average behavior, and estimates the statistical precision of the results.

  4. Determination of the temporal resolution required for the HEDR dose code. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities, Calculation 008

    SciTech Connect

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

    1992-12-01

    A series of scoping calculations has been undertaken to evaluate the radiation doses that may have-been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 008) examined the potential for changes in the uncertainty distributions of potential doses from releases in the year 1945 as a function of temporal resolution of the intermediate data storage. This study builds on the work initiated in the fifth scoping calculation, which addressed the uncertainty of the dose estimates at a point; the sixth calculation, which extrapolated the doses throughout the atmospheric transport domain; and the seventh, which evaluated the spatial scales across the domain. A projection 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 ingestion of cow`s milk.

  5. A correction-based dose calculation algorithm for kilovoltage x rays

    SciTech Connect

    Ding, George X.; Pawlowski, Jason M.; Coffey, Charles W.

    2008-12-15

    Frequent and repeated imaging procedures such as those performed in image-guided radiotherapy (IGRT) programs may add significant dose to radiosensitive organs of radiotherapy patients. It has been shown that kV-CBCT results in doses to bone that are up to a factor of 3-4 higher than those in surrounding soft tissue. Imaging guidance procedures are necessary due to their potential benefits, but the additional incremental dose per treatment fraction may exceed an individual organ tolerance. Hence it is important to manage and account for this additional dose from imaging for radiotherapy patients. Currently available model-based dose calculation methods in radiation treatment planning (RTP) systems are not suitable for low-energy x rays, and new and fast calculation algorithms are needed for a RTP system for kilovoltage dose computations. This study presents a new dose calculation algorithm, referred to as the medium-dependent-correction (MDC) algorithm, for accurate patient dose calculation resulting from kilovoltage x rays. The accuracy of the new algorithm is validated against Monte Carlo calculations. The new algorithm overcomes the deficiency of existing density correction based algorithms in dose calculations for inhomogeneous media, especially for CT-based human volumetric images used in radiotherapy treatment planning.

  6. 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. PMID:20045343

  7. Calculation of Dose Deposition in Nanovolumes and Simulation of gamma-H2AX Experiments

    NASA Technical Reports Server (NTRS)

    Plante, Ianik

    2010-01-01

    Monte-Carlo track structure simulations can accurately simulate experimental data: a) Frequency of target hits. b) Dose per event. c) Dose per ion. d) Radial dose. The dose is uniform in micrometers sized voxels; at the nanometer scale, the difference in energy deposition between high and low-LET radiations appears. The calculated 3D distribution of dose voxels, combined with chromosomes simulated by random walk is very similar to the distribution of DSB observed with gamma-H2AX experiments. This is further evidenced by applying a visualization threshold on dose.

  8. Measurement of Entrance Skin Dose and Calculation of Effective Dose for Common Diagnostic X-Ray Examinations in Kashan, Iran.

    PubMed

    Aliasgharzadeh, Akbar; Mihandoost, Ehsan; Masoumbeigi, Mahboubeh; Salimian, Morteza; Mohseni, Mehran

    2015-01-01

    The knowledge of the radiation dose received by the patient during the radiological examination is essential to prevent risks of exposures. The aim of this work is to study patient doses for common diagnostic radiographic examinations in hospitals affiliated to Kashan University of Medical sciences, Iran. The results of this survey are compared with those published by some national and international values. Entrance surface dose (ESD) was measured based on the exposure parameters used for the actual examination and effective dose (ED) was calculated by use of conversion coefficients calculated by Monte Carlo methods. The mean entrance surface dose and effective dose for examinations of the chest (PA, Lat), abdomen (AP), pelvis (AP), lumbar spine (AP, Lat) and skull (AP, Lat) are 0.37, 0.99, 2.01, 1.76, 2.18, 5.36, 1.39 and 1.01 mGy, and 0.04, 0.1, 0.28, 0,28, 0.23, 0.13, 0.01 and 0.01 mSv, respectively. The ESDs and EDs reported in this study, except for examinations of the chest, are generally lower than comparable reference dose values published in the literature. On the basis of the results obtained in this study can conclude that use of newer equipment and use of the proper radiological parameter can significantly reduce the absorbed dose. It is recommended that radiological parameter in chest examinations be revised. PMID:26156930

  9. Measurement of Entrance Skin Dose and Calculation of Effective Dose for Common Diagnostic X-Ray Examinations in Kashan, Iran

    PubMed Central

    Aliasgharzadeh, Akbar; Mihandoost, Ehsan; Masoumbeigi, Mahboubeh; Salimian, Morteza; Mohseni, Mehran

    2015-01-01

    The knowledge of the radiation dose received by the patient during the radiological examination is essential to prevent risks of exposures. The aim of this work is to study patient doses for common diagnostic radiographic examinations in hospitals affiliated to Kashan University of Medical sciences, Iran. The results of this survey are compared with those published by some national and international values. Entrance surface dose (ESD) was measured based on the exposure parameters used for the actual examination and effective dose (ED) was calculated by use of conversion coefficients calculated by Monte Carlo methods. The mean entrance surface dose and effective dose for examinations of the chest (PA, Lat), abdomen (AP), pelvis (AP), lumbar spine (AP, Lat) and skull (AP, Lat) are 0.37, 0.99, 2.01, 1.76, 2.18, 5.36, 1.39 and 1.01 mGy, and 0.04, 0.1, 0.28, 0,28, 0.23, 0.13, 0.01 and 0.01 mSv, respectively. The ESDs and EDs reported in this study, except for examinations of the chest, are generally lower than comparable reference dose values published in the literature. On the basis of the results obtained in this study can conclude that use of newer equipment and use of the proper radiological parameter can significantly reduce the absorbed dose. It is recommended that radiological parameter in chest examinations be revised. PMID:26156930

  10. High-dose Helical Tomotherapy With Concurrent Full-dose Chemotherapy for Locally Advanced Pancreatic Cancer

    SciTech Connect

    Chang, Jee Suk; Wang, Michael L.C.; Koom, Woong Sub; Yoon, Hong In; Chung, Yoonsun; Song, Si Young; Seong, Jinsil

    2012-08-01

    Purpose: To improve poor therapeutic outcome of current practice of chemoradiotherapy (CRT), high-dose helical tomotherapy (HT) with concurrent full-dose chemotherapy has been performed on patients with locally advanced pancreatic cancer (LAPC), and the results were analyzed. Methods and Materials: We retrospectively reviewed 39 patients with LAPC treated with radiotherapy using HT (median, 58.4 Gy; range, 50.8-59.9 Gy) and concomitant chemotherapy between 2006 and 2009. Radiotherapy was directed to the primary tumor with a 0.5-cm margin without prophylactic nodal coverage. Twenty-nine patients (79%) received full-dose (1000 mg/m{sup 2}) gemcitabine-based chemotherapy during HT. After completion of CRT, maintenance chemotherapy was administered to 37 patients (95%). Results: The median follow-up was 15.5 months (range, 3.4-43.9) for the entire cohort, and 22.5 months (range, 12.0-43.9) for the surviving patients. The 1- and 2-year local progression-free survival rates were 82.1% and 77.3%, respectively. Eight patients (21%) were converted to resectable status, including 1 with a pathological complete response. The median overall survival and progression-free survival were 21.2 and 14.0 months, respectively. Acute toxicities were acceptable with no gastrointestinal (GI) toxicity higher than Grade 3. Severe late GI toxicity ({>=}Grade 3) occurred in 10 patients (26%); 1 treatment-related death from GI bleeding was observed. Conclusion: High-dose helical tomotherapy with concurrent full-dose chemotherapy resulted in improved local control and long-term survival in patients with LAPC. Future studies are needed to widen the therapeutic window by minimizing late GI toxicity.

  11. Advanced Computational Approaches for Characterizing Stochastic Cellular Responses to Low Dose, Low Dose Rate Exposures

    SciTech Connect

    Scott, Bobby, R., Ph.D.

    2003-06-27

    OAK - B135 This project final report summarizes modeling research conducted in the U.S. Department of Energy (DOE), Low Dose Radiation Research Program at the Lovelace Respiratory Research Institute from October 1998 through June 2003. The modeling research described involves critically evaluating the validity of the linear nonthreshold (LNT) risk model as it relates to stochastic effects induced in cells by low doses of ionizing radiation and genotoxic chemicals. The LNT model plays a central role in low-dose risk assessment for humans. With the LNT model, any radiation (or genotoxic chemical) exposure is assumed to increase one¡¯s risk of cancer. Based on the LNT model, others have predicted tens of thousands of cancer deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Our research has focused on developing biologically based models that explain the shape of dose-response curves for low-dose radiation and genotoxic chemical-induced stochastic effects in cells. Understanding the shape of the dose-response curve for radiation and genotoxic chemical-induced stochastic effects in cells helps to better understand the shape of the dose-response curve for cancer induction in humans. We have used a modeling approach that facilitated model revisions over time, allowing for timely incorporation of new knowledge gained related to the biological basis for low-dose-induced stochastic effects in cells. Both deleterious (e.g., genomic instability, mutations, and neoplastic transformation) and protective (e.g., DNA repair and apoptosis) effects have been included in our modeling. Our most advanced model, NEOTRANS2, involves differing levels of genomic instability. Persistent genomic instability is presumed to be associated with nonspecific, nonlethal mutations and to increase both the risk for neoplastic transformation and for cancer occurrence. Our research results, based on

  12. A model to calculate the induced dose rate around an 18 MV ELEKTA linear accelerator.

    PubMed

    Perrin, Bruce; Walker, Anne; Mackay, Ranald

    2003-03-01

    The dose rate due to activity induced by (gamma, n) reactions around an ELEKTA Precise accelerator running at 18 MV is reported. A model to calculate the induced dose rate for a variety of working practices has been derived and compared to the measured values. From this model, the dose received by the staff using the machine can be estimated. From measured dose rates at the face of the linear accelerator for a 10 x 10 cm2 jaw setting at 18 MV an activation coefficient per MU was derived for each of the major activation products. The relative dose rates at points around the linac head, for different energy and jaw settings, were measured. Dose rates adjacent to the patient support system and portal imager were also measured. A model to calculate the dose rate at these points was derived, and compared to those measured over a typical working week. The model was then used to estimate the maximum dose to therapists for the current working schedule on this machine. Calculated dose rates at the linac face agreed to within +/- 12% of those measured over a week, with a typical dose rate of 4.5 microSv h(-1) 2 min after the beam has stopped. The estimated maximum annual whole body dose for a treatment therapist, with the machine treating at only 18 MV, for 60000 MUs per week was 2.5 mSv. This compares well with value of 2.9 mSv published for a Clinac 21EX. A model has been derived to calculate the dose from the four dominant activation products of an ELEKTA Precise 18 MV linear accelerator. This model is a useful tool to calculate the induced dose rate around the treatment head. The model can be used to estimate the dose to the staff for typical working patterns. PMID:12696804

  13. Dose-Response Relationship for Image-Guided Stereotactic Body Radiotherapy of Pulmonary Tumors: Relevance of 4D Dose Calculation

    SciTech Connect

    Guckenberger, Matthias Wulf, Joern; Mueller, Gerd; Krieger, Thomas; Baier, Kurt; Gabor, Manuela; Richter, Anne; Wilbert, Juergen; Flentje, Michael

    2009-05-01

    Purpose: To evaluate outcome after image-guided stereotactic body radiotherapy (SBRT) for early-stage non-small-cell lung cancer (NSCLC) and pulmonary metastases. Methods and Materials: A total of 124 patients with 159 pulmonary lesions (metastases n = 118; NSCLC, n = 41; Stage IA, n = 13; Stage IB, n = 19; T3N0, n = 9) were treated with SBRT. Patients were treated with hypofractionated schemata (one to eight fractions of 6-26 Gy); biologic effective doses (BED) to the clinical target volume (CTV) were calculated based on four-dimensional (4D) dose calculation. The position of the pulmonary target was verified using volume imaging before all treatments. Results: With mean/median follow-up of 18/14 months, actuarial local control was 83% at 36 months with no difference between NSCLC and metastases. The dose to the CTV based on 4D dose calculation was closely correlated with local control: local control rates were 89% and 62% at 36 months for >100 Gy and <100 Gy BED (p = 0.0001), respectively. Actuarial freedom from regional and systemic progression was 34% at 36 months for primary NSCLC group; crude rate of regional failure was 15%. Three-year overall survival was 37% for primary NSCLC and 16% for metastases; no dose-response relationship for survival was observed. Exacerbation of comorbidities was the most frequent cause of death for primary NSCLC. Conclusions: Doses of >100 Gy BED to the CTV based on 4D dose calculation resulted in excellent local control rates. This cutoff dose is not specific to the treatment technique and protocol of our study and may serve as a general recommendation.

  14. Calculation of dose, dose equivalent, and relative biological effectiveness for high charge and energy ion beams

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Chun, S. Y.; Reginatto, M.; Hajnal, F.

    1995-01-01

    The Green's function for the transport of ions of high charge and energy is utilized with a nuclear fragmentation database to evaluate dose, dose equivalent, and RBE for C3H10T1/2 cell survival and neo-plastic transformation as function of depth in soft tissue. Such evaluations are useful to estimates of biological risk for high altitude aircraft, space operations, accelerator operations, and biomedical application.

  15. Investigation of Advanced Dose Verification Techniques for External Beam Radiation Treatment

    NASA Astrophysics Data System (ADS)

    Asuni, Ganiyu Adeniyi

    Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) have been introduced in radiation therapy to achieve highly conformal dose distributions around the tumour while minimizing dose to surrounding normal tissues. These techniques have increased the need for comprehensive quality assurance tests, to verify that customized patient treatment plans are accurately delivered during treatment. in vivo dose verification, performed during treatment delivery, confirms that the actual dose delivered is the same as the prescribed dose, helping to reduce treatment delivery errors. in vivo measurements may be accomplished using entrance or exit detectors. The objective of this project is to investigate a novel entrance detector designed for in vivo dose verification. This thesis is separated into three main investigations, focusing on a prototype entrance transmission detector (TRD) developed by IBA Dosimetry, Germany. First contaminant electrons generated by the TRD in a 6 MV photon beam were investigated using Monte Carlo (MC) simulation. This study demonstrates that modification of the contaminant electron model in the treatment planning system is required for accurate patient dose calculation in buildup regions when using the device. Second, the ability of the TRD to accurately measure dose from IMRT and VMAT was investigated by characterising the spatial resolution of the device. This was accomplished by measuring the point spread function with further validation provided by MC simulation. Comparisons of measured and calculated doses show that the spatial resolution of the TRD allows for measurement of clinical IMRT fields within acceptable tolerance. Finally, a new general research tool was developed to perform MC simulations for VMAT and IMRT treatments, simultaneously tracking dose deposition in both the patient CT geometry and an arbitrary planar detector system, generalized to handle either entrance or exit orientations. It was

  16. The effects of anatomic resolution, respiratory variations and dose calculation methods on lung dosimetry

    NASA Astrophysics Data System (ADS)

    Babcock, Kerry Kent Ronald

    2009-04-01

    The goal of this thesis was to explore the effects of dose resolution, respiratory variation and dose calculation method on dose accuracy. To achieve this, two models of lung were created. The first model, called TISSUE, approximated the connective alveolar tissues of the lung. The second model, called BRANCH, approximated the lungs bronchial, arterial and venous branching networks. Both models were varied to represent the full inhalation, full exhalation and midbreath phases of the respiration cycle. To explore the effects of dose resolution and respiratory variation on dose accuracy, each model was converted into a CT dataset and imported into a Monte Carlo simulation. The resulting dose distributions were compared and contrasted against dose distributions from Monte Carlo simulations which included the explicit model geometries. It was concluded that, regardless of respiratory phase, the exclusion of the connective tissue structures in the CT representation did not significantly effect the accuracy of dose calculations. However, the exclusion of the BRANCH structures resulted in dose underestimations as high as 14% local to the branching structures. As lung density decreased, the overall dose accuracy marginally decreased. To explore the effects of dose calculation method on dose accuracy, CT representations of the lung models were imported into the Pinnacle 3 treatment planning system. Dose distributions were calculated using the collapsed cone convolution method and compared to those derived using the Monte Carlo method. For both lung models, it was concluded that the accuracy of the collapsed cone algorithm decreased with decreasing density. At full inhalation lung density, the collapsed cone algorithm underestimated dose by as much as 15%. Also, the accuracy of the CCC method decreased with decreasing field size. Further work is needed to determine the source of the discrepancy.

  17. Numerical calculation of relative dose rates from spherical 106Ru beta sources used in ophthalmic brachytherapy

    NASA Astrophysics Data System (ADS)

    de Paiva, Eduardo

    Concave beta sources of 106Ru/106Rh are used in radiotherapy to treat ophthalmic tumors. However, a problem that arises is the difficult determination of absorbed dose distributions around such sources mainly because of the small range of the electrons and the steep dose gradients. In this sense, numerical methods have been developed to calculate the dose distributions around the beta applicators. In this work a simple code in Fortran language is developed to estimate the dose rates along the central axis of 106Ru/106Rh curved plaques by numerical integration of the beta point source function and results are compared with other calculated data.

  18. Advanced numerics for multi-dimensional fluid flow calculations

    NASA Technical Reports Server (NTRS)

    Vanka, S. P.

    1984-01-01

    In recent years, there has been a growing interest in the development and use of mathematical models for the simulation of fluid flow, heat transfer and combustion processes in engineering equipment. The equations representing the multi-dimensional transport of mass, momenta and species are numerically solved by finite-difference or finite-element techniques. However despite the multiude of differencing schemes and solution algorithms, and the advancement of computing power, the calculation of multi-dimensional flows, especially three-dimensional flows, remains a mammoth task. The following discussion is concerned with the author's recent work on the construction of accurate discretization schemes for the partial derivatives, and the efficient solution of the set of nonlinear algebraic equations resulting after discretization. The present work has been jointly supported by the Ramjet Engine Division of the Wright Patterson Air Force Base, Ohio, and the NASA Lewis Research Center.

  19. Determination of the feasibility of reducing the spatial domain of the HEDR dose code. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities, Calculation 006

    SciTech Connect

    Napier, B.A.; Snyder, S.F.

    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. The primary impetus for this scoping calculation was to determine if large areas of the Hanford Environmental Dose Reconstruction (HEDR) Project atmospheric domain could be excluded from detailed calculation because the atmospheric transport of radionuclides from Hanford resulted in no (or negligible) deposition in those areas. The secondary impetus was to investigate whether an intermediate screen could be developed to reduce the data storage requirements by taking advantage of locations with periods of ``effectively zero`` deposition. This scoping calculation (Calculation 006) 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 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 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, and (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cow`s milk from Feeding Regime 1 as described in scoping calculation 001.

  20. A generic high-dose rate {sup 192}Ir brachytherapy source for evaluation of model-based dose calculations beyond the TG-43 formalism

    SciTech Connect

    Ballester, Facundo; Carlsson Tedgren, Åsa; Granero, Domingo; Haworth, Annette; Mourtada, Firas; Fonseca, Gabriel Paiva; Rivard, Mark J.; Siebert, Frank-André; Sloboda, Ron S.; and others

    2015-06-15

    Purpose: In order to facilitate a smooth transition for brachytherapy dose calculations from the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) formalism to model-based dose calculation algorithms (MBDCAs), treatment planning systems (TPSs) using a MBDCA require a set of well-defined test case plans characterized by Monte Carlo (MC) methods. This also permits direct dose comparison to TG-43 reference data. Such test case plans should be made available for use in the software commissioning process performed by clinical end users. To this end, a hypothetical, generic high-dose rate (HDR) {sup 192}Ir source and a virtual water phantom were designed, which can be imported into a TPS. Methods: A hypothetical, generic HDR {sup 192}Ir source was designed based on commercially available sources as well as a virtual, cubic water phantom that can be imported into any TPS in DICOM format. The dose distribution of the generic {sup 192}Ir source when placed at the center of the cubic phantom, and away from the center under altered scatter conditions, was evaluated using two commercial MBDCAs [Oncentra{sup ®} Brachy with advanced collapsed-cone engine (ACE) and BrachyVision ACUROS{sup TM}]. Dose comparisons were performed using state-of-the-art MC codes for radiation transport, including ALGEBRA, BrachyDose, GEANT4, MCNP5, MCNP6, and PENELOPE2008. The methodologies adhered to recommendations in the AAPM TG-229 report on high-energy brachytherapy source dosimetry. TG-43 dosimetry parameters, an along-away dose-rate table, and primary and scatter separated (PSS) data were obtained. The virtual water phantom of (201){sup 3} voxels (1 mm sides) was used to evaluate the calculated dose distributions. Two test case plans involving a single position of the generic HDR {sup 192}Ir source in this phantom were prepared: (i) source centered in the phantom and (ii) source displaced 7 cm laterally from the center. Datasets were independently produced by

  1. Scoping calculation for components of the cow-milk dose pathway for evaluating the dose contribution from iodine-131

    SciTech Connect

    Ikenberry, T.A.; Napier, B.A.

    1992-12-01

    A series of scoping calculations have been undertaken to evaluate The absolute and relative contribution of different exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 001) examined the contributions of the various exposure pathways associated with environmental transport and accumulation of iodine-131 in the pasture-cow-milk pathway. Addressed in this calculation were the contributions to thyroid dose of infants and adult from (1) the ingestion by dairy cattle of various feedstuffs (pasturage, silage, alfalfa hay, and grass hay) in four different feeding regimes; (2) ingestion of soil by dairy cattle; (3) ingestion of stared feed on which airborne iodine-131 had been deposited; and (4) inhalation of airborne iodine-131 by dairy cows.

  2. 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.

  3. Using matrix summation method for three dimensional dose calculation in brachytherapy

    PubMed Central

    Zibandeh-Gorji, Mahmoud; Mowlavi, Ali Asghar; Mohammadi, Saeed

    2012-01-01

    Aim The purpose of this study is to calculate radiation dose around a brachytherapy source in a water phantom for different seed locations or rotation the sources by the matrix summation method. Background Monte Carlo based codes like MCNP are widely used for performing radiation transport calculations and dose evaluation in brachytherapy. But for complicated situations, like using more than one source, moving or rotating the source, the routine Monte Carlo method for dose calculation needs a long time running. Materials and methods The MCNPX code has been used to calculate radiation dose around a 192Ir brachytherapy source and saved in a 3D matrix. Then, we used this matrix to evaluate the absorbed dose in any point due to some sources or a source which shifted or rotated in some places by the matrix summation method. Results Three dimensional (3D) dose results and isodose curves were presented for 192Ir source in a water cube phantom shifted for 10 steps and rotated for 45 and 90° based on the matrix summation method. Also, we applied this method for some arrays of sources. Conclusion The matrix summation method can be used for 3D dose calculations for any brachytherapy source which has moved or rotated. This simple method is very fast compared to routine Monte Carlo based methods. In addition, it can be applied for dose optimization study. PMID:24377009

  4. On the use of an analytic source model for dose calculations in precision image-guided small animal radiotherapy

    NASA Astrophysics Data System (ADS)

    Granton, Patrick V.; Verhaegen, Frank

    2013-05-01

    Precision image-guided small animal radiotherapy is rapidly advancing through the use of dedicated micro-irradiation devices. However, precise modeling of these devices in model-based dose-calculation algorithms such as Monte Carlo (MC) simulations continue to present challenges due to a combination of very small beams, low mechanical tolerances on beam collimation, positioning and long calculation times. The specific intent of this investigation is to introduce and demonstrate the viability of a fast analytical source model (AM) for use in either investigating improvements in collimator design or for use in faster dose calculations. MC models using BEAMnrc were developed for circular and square fields sizes from 1 to 25 mm in diameter (or side) that incorporated the intensity distribution of the focal spot modeled after an experimental pinhole image. These MC models were used to generate phase space files (PSFMC) at the exit of the collimators. An AM was developed that included the intensity distribution of the focal spot, a pre-calculated x-ray spectrum, and the collimator-specific entrance and exit apertures. The AM was used to generate photon fluence intensity distributions (ΦAM) and PSFAM containing photons radiating at angles according to the focal spot intensity distribution. MC dose calculations using DOSXYZnrc in a water and mouse phantom differing only by source used (PSFMC versus PSFAM) were found to agree within 7% and 4% for the smallest 1 and 2 mm collimator, respectively, and within 1% for all other field sizes based on depth dose profiles. PSF generation times were approximately 1200 times faster for the smallest beam and 19 times faster for the largest beam. The influence of the focal spot intensity distribution on output and on beam shape was quantified and found to play a significant role in calculated dose distributions. Beam profile differences due to collimator alignment were found in both small and large collimators sensitive to shifts of 1

  5. Comparison of dose calculation algorithms for colorectal cancer brachytherapy treatment with a shielded applicator

    SciTech Connect

    Yan Xiangsheng; Poon, Emily; Reniers, Brigitte; Vuong, Te; Verhaegen, Frank

    2008-11-15

    Colorectal cancer patients are treated at our hospital with {sup 192}Ir high dose rate (HDR) brachytherapy using an applicator that allows the introduction of a lead or tungsten shielding rod to reduce the dose to healthy tissue. The clinical dose planning calculations are, however, currently performed without taking the shielding into account. To study the dose distributions in shielded cases, three techniques were employed. The first technique was to adapt a shielding algorithm which is part of the Nucletron PLATO HDR treatment planning system. The isodose pattern exhibited unexpected features but was found to be a reasonable approximation. The second technique employed a ray tracing algorithm that assigns a constant dose ratio with/without shielding behind the shielding along a radial line originating from the source. The dose calculation results were similar to the results from the first technique but with improved accuracy. The third and most accurate technique used a dose-matrix-superposition algorithm, based on Monte Carlo calculations. The results from the latter technique showed quantitatively that the dose to healthy tissue is reduced significantly in the presence of shielding. However, it was also found that the dose to the tumor may be affected by the presence of shielding; for about a quarter of the patients treated the volume covered by the 100% isodose lines was reduced by more than 5%, leading to potential tumor cold spots. Use of any of the three shielding algorithms results in improved dose estimates to healthy tissue and the tumor.

  6. Validation of dose planning calculations for boron neutron capture therapy using cylindrical and anthropomorphic phantoms

    NASA Astrophysics Data System (ADS)

    Koivunoro, Hanna; Seppälä, Tiina; Uusi-Simola, Jouni; Merimaa, Katja; Kotiluoto, Petri; Serén, Tom; Kortesniemi, Mika; Auterinen, Iiro; Savolainen, Sauli

    2010-06-01

    In this paper, the accuracy of dose planning calculations for boron neutron capture therapy (BNCT) of brain and head and neck cancer was studied at the FiR 1 epithermal neutron beam. A cylindrical water phantom and an anthropomorphic head phantom were applied with two beam aperture-to-surface distances (ASD). The calculations using the simulation environment for radiation application (SERA) treatment planning system were compared to neutron activation measurements with Au and Mn foils, photon dose measurements with an ionization chamber and the reference simulations with the MCNP5 code. Photon dose calculations using SERA differ from the ionization chamber measurements by 2-13% (disagreement increased along the depth in the phantom), but are in agreement with the MCNP5 calculations within 2%. The 55Mn(n,γ) and 197Au(n,γ) reaction rates calculated using SERA agree within 10% and 8%, respectively, with the measurements and within 5% with the MCNP5 calculations at depths >0.5 cm from the phantom surface. The 55Mn(n,γ) reaction rate represents the nitrogen and boron depth dose within 1%. Discrepancy in the SERA fast neutron dose calculation (of up to 37%) is corrected if the biased fast neutron dose calculation option is not applied. Reduced voxel cell size (<=0.5 cm) improves the SERA calculation accuracy on the phantom surface. Despite the slight overestimation of the epithermal neutrons and underestimation of the thermal neutrons in the beam model, neutron calculation accuracy with the SERA system is sufficient for reliable BNCT treatment planning with the two studied treatment distances. The discrepancy between measured and calculated photon dose remains unsatisfactorily high for depths >6 cm from the phantom surface. Increasing discrepancy along the phantom depth is expected to be caused by the inaccurately determined effective point of the ionization chamber.

  7. The effect of statistical uncertainty on inverse treatment planning based on Monte Carlo dose calculation

    NASA Astrophysics Data System (ADS)

    Jeraj, Robert; Keall, Paul

    2000-12-01

    The effect of the statistical uncertainty, or noise, in inverse treatment planning for intensity modulated radiotherapy (IMRT) based on Monte Carlo dose calculation was studied. Sets of Monte Carlo beamlets were calculated to give uncertainties at Dmax ranging from 0.2% to 4% for a lung tumour plan. The weights of these beamlets were optimized using a previously described procedure based on a simulated annealing optimization algorithm. Several different objective functions were used. It was determined that the use of Monte Carlo dose calculation in inverse treatment planning introduces two errors in the calculated plan. In addition to the statistical error due to the statistical uncertainty of the Monte Carlo calculation, a noise convergence error also appears. For the statistical error it was determined that apparently successfully optimized plans with a noisy dose calculation (3% 1σ at Dmax ), which satisfied the required uniformity of the dose within the tumour, showed as much as 7% underdose when recalculated with a noise-free dose calculation. The statistical error is larger towards the tumour and is only weakly dependent on the choice of objective function. The noise convergence error appears because the optimum weights are determined using a noisy calculation, which is different from the optimum weights determined for a noise-free calculation. Unlike the statistical error, the noise convergence error is generally larger outside the tumour, is case dependent and strongly depends on the required objectives.

  8. 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.

  9. 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. PMID:26040956

  10. Dose calculation from a D-D-reaction-based BSA for boron neutron capture synovectomy.

    PubMed

    Abdalla, Khalid; Naqvi, A A; Maalej, N; Elshahat, B

    2010-01-01

    Monte Carlo simulations were carried out to calculate dose in a knee phantom from a D-D-reaction-based Beam Shaping Assembly (BSA) for Boron Neutron Capture Synovectomy (BNCS). The BSA consists of a D(d,n)-reaction-based neutron source enclosed inside a polyethylene moderator and graphite reflector. The polyethylene moderator and graphite reflector sizes were optimized to deliver the highest ratio of thermal to fast neutron yield at the knee phantom. Then neutron dose was calculated at various depths in a knee phantom loaded with boron and therapeutic ratios of synovium dose/skin dose and synovium dose/bone dose were determined. Normalized to same boron loading in synovium, the values of the therapeutic ratios obtained in the present study are 12-30 times higher than the published values. PMID:19828325

  11. Influence of polarization and a source model for dose calculation in MRT

    SciTech Connect

    Bartzsch, Stefan Oelfke, Uwe; Lerch, Michael; Petasecca, Marco; Bräuer-Krisch, Elke

    2014-04-15

    Purpose: Microbeam Radiation Therapy (MRT), an alternative preclinical treatment strategy using spatially modulated synchrotron radiation on a micrometer scale, has the great potential to cure malignant tumors (e.g., brain tumors) while having low side effects on normal tissue. Dose measurement and calculation in MRT is challenging because of the spatial accuracy required and the arising high dose differences. Dose calculation with Monte Carlo simulations is time consuming and their accuracy is still a matter of debate. In particular, the influence of photon polarization has been discussed in the literature. Moreover, it is controversial whether a complete knowledge of phase space trajectories, i.e., the simulation of the machine from the wiggler to the collimator, is necessary in order to accurately calculate the dose. Methods: With Monte Carlo simulations in the Geant4 toolkit, the authors investigate the influence of polarization on the dose distribution and the therapeutically important peak to valley dose ratios (PVDRs). Furthermore, the authors analyze in detail phase space information provided byMartínez-Rovira et al. [“Development and commissioning of a Monte Carlo photon model for the forthcoming clinical trials in microbeam radiation therapy,” Med. Phys. 39(1), 119–131 (2012)] and examine its influence on peak and valley doses. A simple source model is developed using parallel beams and its applicability is shown in a semiadjoint Monte Carlo simulation. Results are compared to measurements and previously published data. Results: Polarization has a significant influence on the scattered dose outside the microbeam field. In the radiation field, however, dose and PVDRs deduced from calculations without polarization and with polarization differ by less than 3%. The authors show that the key consequences from the phase space information for dose calculations are inhomogeneous primary photon flux, partial absorption due to inclined beam incidence outside

  12. Code System for Calculating Internal and External Doses Resulting from an Atmospheric Release of Radioactive Material.

    1982-06-15

    WRAITH calculates the atmospheric transport of radioactive material to each of a number of downwind receptor points and the external and internal doses to a reference man at each of the receptor points.

  13. The work of the ICRP dose calculational task group: Issues in implementation of the ICRP dosimetric methodology

    SciTech Connect

    Eckerman, K.F.

    1999-01-01

    Committee 2 of the International Commission on Radiological Protection (ICRP) has had efforts underway to provide the radiation protection community with age-dependent dose coefficients, i.e.g, the dose per unit intake. The Task Group on Dose Calculations, chaired by the author, is responsible for the computation of these coefficients. The Task Group, formed in 1974 to produce ICRP Publication 30, is now international in its membership and its work load has been distributed among the institutions represented on the task group. This paper discusses: (1) recent advances in biokinetic modeling; (2) the recent changes in the dosimetric methodology; (3) the novel computational problems with some of the ICRP quantities; and (4) quality assurance issues which the Task Group has encountered. Potential future developments of the dosimetric framework which might strengthen the relationships with the emerging understanding of radiation risk will also be discussed.

  14. Calculation of Residual Dose Around Small Objects Using Mu2e Target as an Example

    SciTech Connect

    Pronskikh, V.S.; Leveling, A.F.; Mokhov, N.V.; Rakhno, I.L.; Aarnio, P.; /Aalto U.

    2011-09-01

    The MARS15 code provides contact residual dose rates for relatively large accelerator and experimental components for predefined irradiation and cooling times. The dose rate at particular distances from the components, some of which can be rather small in size, is calculated in a post Monte-Carlo stage via special algorithms described elsewhere. The approach is further developed and described in this paper.

  15. An evaluation of calculation parameters in the EGSnrc/BEAMnrc Monte Carlo codes and their effect on surface dose calculation

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Ha; Hill, Robin; Kuncic, Zdenka

    2012-07-01

    The Monte Carlo (MC) method has proven invaluable for radiation transport simulations to accurately determine radiation doses and is widely considered a reliable computational measure that can substitute a physical experiment where direct measurements are not possible or feasible. In the EGSnrc/BEAMnrc MC codes, there are several user-specified parameters and customized transport algorithms, which may affect the calculation results. In order to fully utilize the MC methods available in these codes, it is essential to understand all these options and to use them appropriately. In this study, the effects of the electron transport algorithms in EGSnrc/BEAMnrc, which are often a trade-off between calculation accuracy and efficiency, were investigated in the buildup region of a homogeneous water phantom and also in a heterogeneous phantom using the DOSRZnrc user code. The algorithms and parameters investigated include: boundary crossing algorithm (BCA), skin depth, electron step algorithm (ESA), global electron cutoff energy (ECUT) and electron production cutoff energy (AE). The variations in calculated buildup doses were found to be larger than 10% for different user-specified transport parameters. We found that using BCA = EXACT gave the best results in terms of accuracy and efficiency in calculating buildup doses using DOSRZnrc. In addition, using the ESA = PRESTA-I option was found to be the best way of reducing the total calculation time without losing accuracy in the results at high energies (few keV ∼ MeV). We also found that although choosing a higher ECUT/AE value in the beam modelling can dramatically improve computation efficiency, there is a significant trade-off in surface dose uncertainty. Our study demonstrates that a careful choice of user-specified transport parameters is required when conducting similar MC calculations.

  16. HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators

    SciTech Connect

    Chibani, Omar C-M Ma, Charlie

    2014-05-15

    Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR

  17. On the Sensitivity of α/β Prediction to Dose Calculation Methodology in Prostate Brachytherapy

    SciTech Connect

    Afsharpour, Hossein; Walsh, Sean; Collins Fekete, Charles-Antoine; Vigneault, Eric; Verhaegen, Frank; Beaulieu, Luc

    2014-02-01

    Purpose: To study the relationship between the accuracy of the dose calculation in brachytherapy and the estimations of the radiosensitivity parameter, α/β, for prostate cancer. Methods and Materials: In this study, Monte Carlo methods and more specifically the code ALGEBRA was used to produce accurate dose calculations in the case of prostate brachytherapy. Equivalent uniform biologically effective dose was calculated for these dose distributions and was used in an iso-effectiveness relationship with external beam radiation therapy. Results: By considering different levels of detail in the calculations, the estimation for the α/β parameter varied from 1.9 to 6.3 Gy, compared with a value of 3.0 Gy suggested by the American Association of Physicists in Medicine Task Group 137. Conclusions: Large variations of the α/β show the sensitivity of this parameter to dose calculation modality. The use of accurate dose calculation engines is critical for better evaluating the biological outcomes of treatments.

  18. Analysis of the dose calculation accuracy for IMRT in lung: a 2D approach.

    PubMed

    Dvorak, Pavel; Stock, Markus; Kroupa, Bernhard; Bogner, Joachim; Georg, Dietmar

    2007-01-01

    The purpose of this study was to compare the dosimetric accuracy of IMRT plans for targets in lung with the accuracy of standard uniform-intensity conformal radiotherapy for different dose calculation algorithms. Tests were performed utilizing a special phantom manufactured from cork and polystyrene in order to quantify the uncertainty of two commercial TPS for IMRT in the lung. Ionization and film measurements were performed at various measuring points/planes. Additionally, single-beam and uniform-intensity multiple-beam tests were performed, in order to investigate deviations due to other characteristics of IMRT. Helax-TMS V6.1(A) was tested for 6, 10 and 25 MV and BrainSCAN 5.2 for 6 MV photon beams, respectively. Pencil beam (PB) with simple inhomogeneity correction and 'collapsed cone' (CC) algorithms were applied for dose calculations. However, the latter was not incorporated during optimization hence only post-optimization recalculation was tested. Two-dimensional dose distributions were evaluated applying the gamma index concept. Conformal plans showed the same accuracy as IMRT plans. Ionization chamber measurements detected deviations of up to 5% when a PB algorithm was used for IMRT dose calculations. Significant improvement (deviations approximately 2%) was observed when IMRT plans were recalculated with the CC algorithm, especially for the highest nominal energy. All gamma evaluations confirmed substantial improvement with the CC algorithm in 2D. While PB dose distributions showed most discrepancies in lower (<50%) and high (>90%) dose regions, the CC dose distributions deviated mainly in the high dose gradient (20-80%) region. The advantages of IMRT (conformity, intra-target dose control) should be counterbalanced with possible calculation inaccuracies for targets in the lung. Until no superior dose calculation algorithms are involved in the iterative optimization process it should be used with great care. When only PB algorithm with simple

  19. Determination of the contribution of livestock water ingestion to dose from the cow-milk pathway. Hanford Environmental Dose Reconstruction Project: Dose code recovery activities, Calculation 002

    SciTech Connect

    Ikenberry, T.A.

    1992-12-01

    As part of the Hanford Environmental Dose Reconstruction (HEDR) Project, a series of calculations has been undertaken to evaluate the absolute and relative contribution of different exposure pathways to thyroid doses that may have been received by individuals living in the vicinity of the Hanford Site. These evaluations include some pathways that were included in the Phase I air-pathway dose evaluations (HEDR staff 1991, page xx), as well as other potential exposure pathways being evaluated for possible inclusion in the future HEDR modeling efforts. This calculation (002) examined the possible doses that may have been received by individuals who drank milk from cows that drank from sources of water (stock tanks and farm ponds) exposed to iodine-131 in the atmosphere during 1945.

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

    SciTech Connect

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

    2014-07-15

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

  1. TH-A-19A-09: Towards Sub-Second Proton Dose Calculation On GPU

    SciTech Connect

    Silva, J da

    2014-06-15

    Purpose: To achieve sub-second dose calculation for clinically relevant proton therapy treatment plans. Rapid dose calculation is a key component of adaptive radiotherapy, necessary to take advantage of the better dose conformity offered by hadron therapy. Methods: To speed up proton dose calculation, the pencil beam algorithm (PBA; clinical standard) was parallelised and implemented to run on a graphics processing unit (GPU). The implementation constitutes the first PBA to run all steps on GPU, and each part of the algorithm was carefully adapted for efficiency. Monte Carlo (MC) simulations obtained using Fluka of individual beams of energies representative of the clinical range impinging on simple geometries were used to tune the PBA. For benchmarking, a typical skull base case with a spot scanning plan consisting of a total of 8872 spots divided between two beam directions of 49 energy layers each was provided by CNAO (Pavia, Italy). The calculations were carried out on an Nvidia Geforce GTX680 desktop GPU with 1536 cores running at 1006 MHz. Results: The PBA reproduced within ±3% of maximum dose results obtained from MC simulations for a range of pencil beams impinging on a water tank. Additional analysis of more complex slab geometries is currently under way to fine-tune the algorithm. Full calculation of the clinical test case took 0.9 seconds in total, with the majority of the time spent in the kernel superposition step. Conclusion: The PBA lends itself well to implementation on many-core systems such as GPUs. Using the presented implementation and current hardware, sub-second dose calculation for a clinical proton therapy plan was achieved, opening the door for adaptive treatment. The successful parallelisation of all steps of the calculation indicates that further speedups can be expected with new hardware, brightening the prospects for real-time dose calculation. This work was funded by ENTERVISION, European Commission FP7 grant 264552.

  2. Comparison of conventional and Monte Carlo dose calculations for prostate treatments

    NASA Astrophysics Data System (ADS)

    Fraser, D.; Mark, C.; Cury, F.; Chang, A.; Verhaegen, F.

    2008-02-01

    Monte Carlo (MC) calculations are rapidly finding their place in clinical dose assessments. We investigated conformal prostate dose distributions as calculated by MC, and compared them to several analytical dose calculations. The treatment distributions for twenty prostate cancer patients, treated with 18 MV 3D conformal radiation therapy, were retrospectively assessed. The BEAM code based on EGSnrc was used to model the beam from which phase space files were used as input into the XVMC algorithm. This was compared to conventional treatment planning system calculations (CADPLAN) with and without inhomogeneity corrections. Results indicate that the CADPLAN generalized Batho Power Law, modified Batho Power Law, and equivalent tissue-air ratio methods contain inaccuracies in calculated dose to 95 % of the prostate planning target volume of 3.5 %, 3.3 %, and 2.9 %, respectively. The greatest discrepancies in the organs at risk were seen in the bladder where the inhomogeneity correction methods all predicted that 50 % of the prescribed dose covered an average of 8.2 % more of the bladder volume than that predicted from the MC calculation. Water equivalent MC and water equivalent CADPLAN calculations revealed important discrepancies on the same order as those between heterogeneous MC and heterogeneous CADPLAN calculations. The data indicate that the effect of inhomogeneities is greater in the target volume than the organs at risk, and that accurately modeling the dose deposition process is important for each patient geometry, and may have a greater impact on the dose distribution in the prostate region than correcting an analytical algorithm for the presence of inhomogeneities.

  3. 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.

  4. Effects of the difference in tube voltage of the CT scanner on dose calculation

    NASA Astrophysics Data System (ADS)

    Rhee, Dong Joo; Kim, Sung-woo; Jeong, Dong Hyeok; Moon, Young Min; Kim, Jung Ki

    2015-07-01

    Computed tomography (CT) measures the attenuation coefficient of an object and converts the value assigned to each voxel into a CT number. In radiation therapy, the CT number, which is directly proportional to the linear attenuation coefficient, must be converted to an electron density for radiation dose calculations for cancer treatment. However, if various tube voltages are applied to take the patient's CT image without applying the specific CT number to the electron density conversion curve, the accuracy of the dose calculation is not assured. In this study, changes in CT numbers for different materials due to changes in the tube voltage were demonstrated, and the dose calculation errors in the percentage depth dose (PDD), along with a clinical case were analyzed. The maximum dose difference in the PDD from the treatment planning system (TPS) dose calculation and from the Monte Carlo simulation were 1.3% and 1.1%, respectively, when applying the same CT number to the electron density conversion curve for the 80-kVp and 140-kVp images. In the clinical case, different CT number to electron density conversion curves at tube voltage of 80 kVp and 140 kVp were applied to the same image and the maximum differences in the mean, maximum, and minimum doses were 1.1%, 1.2%, and 1.0%, respectively, at the central region of the phantom and 0.6%, 0.9%, and 0.8%, respectively, at the peripheral region of the phantom.

  5. Computer subroutines for the estimation of nuclear reaction effects in proton-tissue-dose calculations

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Khandelwal, G. S.

    1976-01-01

    Calculational methods for estimation of dose from external proton exposure of arbitrary convex bodies are briefly reviewed. All the necessary information for the estimation of dose in soft tissue is presented. Special emphasis is placed on retaining the effects of nuclear reaction, especially in relation to the dose equivalent. Computer subroutines to evaluate all of the relevant functions are discussed. Nuclear reaction contributions for standard space radiations are in most cases found to be significant. Many of the existing computer programs for estimating dose in which nuclear reaction effects are neglected can be readily converted to include nuclear reaction effects by use of the subroutines described herein.

  6. Calculating patient-specific doses in X-ray diagnostics and from radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Lampinen, Juha Sakari

    2000-06-01

    The risk associated with exposure to ionising radiation is dependent on the characteristics of the exposed individual. The size and structure of the individual influences the absorbed dose distribution in the organs. Traditional methods used to calculate the patient organ doses are based on standardised calculation phantoms, which neglect the variance of the patient size or even sex. Methods for patient specific dosimetry in the fields of X-ray diagnostics and diagnostic and therapeutic use of radiopharmaceuticals were proposed in this thesis. A computer program, ODS-60, for calculating organ doses from diagnostic X-ray exposures was presented. The calculation is done in a patient specific phantom with depth dose and profile algorithms fitted to Monte Carlo simulation data from a previous study. Improvements to the version reported earlier were introduced, e.g. bone attenuation was implemented. The applicability of the program to determine patient doses from complex X-ray examinations (barium enema examination) was studied. The conversion equations derived for female and male patients as a function of patient weight gave the smallest deviation from the actual patient doses when compared to previous studies. Another computer program, Intdose, was presented for calculation of the dose distribution from radiopharmaceuticals. The calculation is based on convolution of an isotope specific point dose kernel with activity distribution, obtained from single photon emission computed tomography (SPECT) images. Anatomical information is taken from magnetic resonance (MR) or computed tomography (CT) images. According to a phantom study, Intdose agreed within 3% with measurements. For volunteers administered diagnostic radiopharmaceuticals, the results given by Intdose were found to agree with traditional methods in cases of medium sized patients. For patients undergoing systemic radiation therapy, the results by Intdose differed from measurements due to dynamic biodistribution

  7. Neutron and photon effective dose equivalent rate calculations for the repackaging of tru waste

    SciTech Connect

    Sattelberger, J. A.

    2002-01-01

    Neutron and photon effective dose equivalent rates were estimated for operations that will occur in the characterization and repackaging of transuranic (TRU) waste drums. These activities will be performed in structures called Mobile Units (MU). A MU is defined as a modular and transportable container, also called a transportainer. The transportainers have been designed to house a process required for certification of TRU wastes. The purpose of these calculations was to provide dose rates from Pu-238 TRU waste in various locations in the transportainer using MCNP-4C. In addition to dose rates for the various radiological operations in the repackaging area, the dose rate from the adjacent storage area was calculated to determine the contribution to the total dose rate.

  8. NOTE: Verification of lung dose in an anthropomorphic phantom calculated by the collapsed cone convolution method

    NASA Astrophysics Data System (ADS)

    Butson, Martin J.; Elferink, Rebecca; Cheung, Tsang; Yu, Peter K. N.; Stokes, Michael; You Quach, Kim; Metcalfe, Peter

    2000-11-01

    Verification of calculated lung dose in an anthropomorphic phantom is performed using two dosimetry media. Dosimetry is complicated by factors such as variations in density at slice interfaces and appropriate position on CT scanning slice to accommodate these factors. Dose in lung for a 6 MV and 10 MV anterior-posterior field was calculated with a collapsed cone convolution method using an ADAC Pinnacle, 3D planning system. Up to 5% variations between doses calculated at the centre and near the edge of the 2 cm phantom slice positioned at the beam central axis were seen, due to the composition of each phantom slice. Validation of dose was performed with LiF thermoluminescent dosimeters (TLDs) and X-Omat V radiographic film. Both dosimetry media produced dose results which agreed closely with calculated results nearest their physical positioning in the phantom. The collapsed cone convolution method accurately calculates dose within inhomogeneous lung regions at 6 MV and 10 MV x-ray energy.

  9. SU-E-T-67: Clinical Implementation and Evaluation of the Acuros Dose Calculation Algorithm

    SciTech Connect

    Yan, C; Combine, T; Dickens, K; Wynn, R; Pavord, D; Huq, M

    2014-06-01

    Purpose: The main aim of the current study is to present a detailed description of the implementation of the Acuros XB Dose Calculation Algorithm, and subsequently evaluate its clinical impacts by comparing it with AAA algorithm. Methods: 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 evaluated by comparing calculated dose with measured dose on a homogeneous water phantom for field sizes ranging from 6cm × 6cm to 40cm × 40cm. Central axis and off-axis points with different depths were chosen for the comparison. Similarly, wedge fields with wedge angles from 15 to 60 degree were used. In addition, variable field sizes for a heterogeneous phantom were used to evaluate the Acuros algorithm. Finally, both Acuros and AAA were tested on VMAT patient plans for various sites. Does distributions and calculation time were compared. Results: On average, computation time is reduced by at least 50% by Acuros XB compared with AAA on single fields and VMAT plans. When used for open 6MV photon beams on homogeneous water phantom, both Acuros XB and AAA calculated doses were within 1% of measurement. For 23 MV photon beams, the calculated doses were within 1.5% of measured doses for Acuros XB and 2% for AAA. When heterogeneous phantom was used, Acuros XB also improved on accuracy. Conclusion: Compared with AAA, Acuros XB can improve accuracy while significantly reduce computation time for VMAT plans.

  10. Study on GEANT4 code applications to dose calculation using imaging data

    NASA Astrophysics Data System (ADS)

    Lee, Jeong Ok; Kang, Jeong Ku; Kim, Jhin Kee; Kwon, Hyeong Cheol; Kim, Jung Soo; Kim, Bu Gil; Jeong, Dong Hyeok

    2015-07-01

    The use of the GEANT4 code has increased in the medical field. Various studies have calculated the patient dose distributions by users the GEANT4 code with imaging data. In present study, Monte Carlo simulations based on DICOM data were performed to calculate the dose absorb in the patient's body. Various visualization tools are installed in the GEANT4 code to display the detector construction; however, the display of DICOM images is limited. In addition, to displaying the dose distributions on the imaging data of the patient is difficult. Recently, the gMocren code, a volume visualization tool for GEANT4 simulation, was developed and has been used in volume visualization of image files. In this study, the imaging based on the dose distributions absorbed in the patients was performed by using the gMocren code. Dosimetric evaluations with were carried out by using thermo luminescent dosimeter and film dosimetry to verify the calculated results.

  11. Independent calculation of dose distributions for helical tomotherapy using a conventional treatment planning system

    SciTech Connect

    Klüter, Sebastian Schubert, Kai; Lissner, Steffen; Sterzing, Florian; Oetzel, Dieter; Debus, Jürgen; Schlegel, Wolfgang; Oelfke, Uwe; Nill, Simeon

    2014-08-15

    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 treatment 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

  12. Dose calculation accuracy of lung planning with a commercial IMRT treatment planning system.

    PubMed

    McDermott, Patrick N; He, Tongming; DeYoung, A

    2003-01-01

    The dose calculation accuracy of a commercial pencil beam IMRT planning system is evaluated by comparison with Monte Carlo calculations and measurements in an anthropomorphic phantom. The target volume is in the right lung and mediastinum and thus significant tissue inhomogeneities are present. The Monte Carlo code is an adaptation of the MCNP code and the measurements were made with TLD and film. Both the Monte Carlo code and the measurements show very good agreement with the treatment planning system except in regions where the dose is high and the electron density is low. In these regions the commercial system shows doses up to 10% higher than Monte Carlo and film. The average calculated dose for the CTV is 5% higher with the commercial system as compared to Monte Carlo. PMID:14604424

  13. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G. ); Poston, J.W. . Dept. of Nuclear Engineering)

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No diffusion of the radionuclide into the blood vessel was assumed nor cross fire between vessel was assumed. Results are useful in assessing the dose in blood and blood vessel walls for different nuclear medicine procedures. 6 refs., 6 figs., 5 tabs.

  14. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G.; Poston, J.W. Sr. )

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No penetration of the radionuclide into the blood vessel was assumed nor was cross fire between the vessel assumed. The results are useful in assessing the dose to blood and blood vessel walls for different nuclear medicine procedures.

  15. Calculation of Ambient (H*(10)) and Personal (Hp(10)) Dose Equivalent from a 252Cf Neutron Source

    SciTech Connect

    Traub, Richard J.

    2010-03-26

    The purpose of this calculation is to calculate the neutron dose factors for the Sr-Cf-3000 neutron source that is located in the 318 low scatter room (LSR). The dose factors were based on the dose conversion factors published in ICRP-21 Appendix 6, and the Ambient dose equivalent (H*(10)) and Personal dose equivalent (Hp(10)) dose factors published in ICRP Publication 74.

  16. Benchmarking of Monte Carlo based shutdown dose rate calculations for applications to JET.

    PubMed

    Petrizzi, L; Batistoni, P; Fischer, U; Loughlin, M; Pereslavtsev, P; Villari, R

    2005-01-01

    The calculation of dose rates after shutdown is an important issue for operating nuclear reactors. A validated computational tool is needed for reliable dose rate calculations. In fusion reactors neutrons induce high levels of radioactivity and presumably high doses. The complex geometries of the devices require the use of sophisticated geometry modelling and computational tools for transport calculations. Simple rule of thumb laws do not always apply well. Two computational procedures have been developed recently and applied to fusion machines. Comparisons between the two methods showed some inherent discrepancies when applied to calculation for the ITER while good agreement was found for a 14 MeV point source neutron benchmark experiment. Further benchmarks were considered necessary to investigate in more detail the reasons for the different results in different cases. In this frame the application to the Joint European Torus JET machine has been considered as a useful benchmark exercise. In a first calculational benchmark with a representative D-T irradiation history of JET the two methods differed by no more than 25%. In another, more realistic benchmark exercise, which is the subject of this paper, the real irradiation history of D-T and D-D campaigns conducted at JET in 1997-98 were used to calculate the shut-down doses at different locations, irradiation and decay times. Experimental dose data recorded at JET for the same conditions offer the possibility to check the prediction capability of the calculations and thus show the applicability (and the constraints) of the procedures and data to the rather complex shutdown dose rate analysis of real fusion devices. Calculation results obtained by the two methods are reported below, comparison with experimental results give discrepancies ranging between 2 and 10. The reasons of that can be ascribed to the high uncertainty on the experimental data and the unsatisfactory JET model used in the calculation. A new

  17. A design of a DICOM-RT-based tool box for nonrigid 4D dose calculation.

    PubMed

    Wong, Victy Y W; Baker, Colin R; Leung, T W; Tung, Stewart Y

    2016-01-01

    The study was aimed to introduce a design of a DICOM-RT-based tool box to facilitate 4D dose calculation based on deformable voxel-dose registration. The computational structure and the calculation algorithm of the tool box were explicitly discussed in the study. The tool box was written in MATLAB in conjunction with CERR. It consists of five main functions which allow a) importation of DICOM-RT-based 3D dose plan, b) deformable image registration, c) tracking voxel doses along breathing cycle, d) presentation of temporal dose distribution at different time phase, and e) derivation of 4D dose. The efficacy of using the tool box for clinical application had been verified with nine clinical cases on retrospective-study basis. The logistic and the robustness of the tool box were tested with 27 applications and the results were shown successful with no computational errors encountered. In the study, the accumulated dose coverage as a function of planning CT taken at end-inhale, end-exhale, and mean tumor position were assessed. The results indicated that the majority of the cases (67%) achieved maximum target coverage, while the planning CT was taken at the temporal mean tumor position and 56% at the end-exhale position. The comparable results to the literature imply that the studied tool box can be reliable for 4D dose calculation. The authors suggest that, with proper application, 4D dose calculation using deformable registration can provide better dose evaluation for treatment with moving target. PMID:27074476

  18. Fast Pencil Beam Dose Calculation for Proton Therapy Using a Double-Gaussian Beam Model

    PubMed Central

    da Silva, Joakim; Ansorge, Richard; Jena, Rajesh

    2015-01-01

    The highly conformal dose distributions produced by scanned proton pencil beams (PBs) are more sensitive to motion and anatomical changes than those produced by conventional radiotherapy. The ability to calculate the dose in real-time as it is being delivered would enable, for example, online dose monitoring, and is therefore highly desirable. We have previously described an implementation of a PB algorithm running on graphics processing units (GPUs) intended specifically for online dose calculation. Here, we present an extension to the dose calculation engine employing a double-Gaussian beam model to better account for the low-dose halo. To the best of our knowledge, it is the first such PB algorithm for proton therapy running on a GPU. We employ two different parameterizations for the halo dose, one describing the distribution of secondary particles from nuclear interactions found in the literature and one relying on directly fitting the model to Monte Carlo simulations of PBs in water. Despite the large width of the halo contribution, we show how in either case the second Gaussian can be included while prolonging the calculation of the investigated plans by no more than 16%, or the calculation of the most time-consuming energy layers by about 25%. Furthermore, the calculation time is relatively unaffected by the parameterization used, which suggests that these results should hold also for different systems. Finally, since the implementation is based on an algorithm employed by a commercial treatment planning system, it is expected that with adequate tuning, it should be able to reproduce the halo dose from a general beam line with sufficient accuracy. PMID:26734567

  19. Fast Pencil Beam Dose Calculation for Proton Therapy Using a Double-Gaussian Beam Model.

    PubMed

    da Silva, Joakim; Ansorge, Richard; Jena, Rajesh

    2015-01-01

    The highly conformal dose distributions produced by scanned proton pencil beams (PBs) are more sensitive to motion and anatomical changes than those produced by conventional radiotherapy. The ability to calculate the dose in real-time as it is being delivered would enable, for example, online dose monitoring, and is therefore highly desirable. We have previously described an implementation of a PB algorithm running on graphics processing units (GPUs) intended specifically for online dose calculation. Here, we present an extension to the dose calculation engine employing a double-Gaussian beam model to better account for the low-dose halo. To the best of our knowledge, it is the first such PB algorithm for proton therapy running on a GPU. We employ two different parameterizations for the halo dose, one describing the distribution of secondary particles from nuclear interactions found in the literature and one relying on directly fitting the model to Monte Carlo simulations of PBs in water. Despite the large width of the halo contribution, we show how in either case the second Gaussian can be included while prolonging the calculation of the investigated plans by no more than 16%, or the calculation of the most time-consuming energy layers by about 25%. Furthermore, the calculation time is relatively unaffected by the parameterization used, which suggests that these results should hold also for different systems. Finally, since the implementation is based on an algorithm employed by a commercial treatment planning system, it is expected that with adequate tuning, it should be able to reproduce the halo dose from a general beam line with sufficient accuracy. PMID:26734567

  20. SU-E-I-28: Evaluating the Organ Dose From Computed Tomography Using Monte Carlo Calculations

    SciTech Connect

    Ono, T; Araki, F

    2014-06-01

    Purpose: To evaluate organ doses from computed tomography (CT) using Monte Carlo (MC) calculations. Methods: A Philips Brilliance CT scanner (64 slice) was simulated using the GMctdospp (IMPS, Germany) based on the EGSnrc user code. The X-ray spectra and a bowtie filter for MC simulations were determined to coincide with measurements of half-value layer (HVL) and off-center ratio (OCR) profile in air. The MC dose was calibrated from absorbed dose measurements using a Farmer chamber and a cylindrical water phantom. The dose distribution from CT was calculated using patient CT images and organ doses were evaluated from dose volume histograms. Results: The HVLs of Al at 80, 100, and 120 kV were 6.3, 7.7, and 8.7 mm, respectively. The calculated HVLs agreed with measurements within 0.3%. The calculated and measured OCR profiles agreed within 3%. For adult head scans (CTDIvol) =51.4 mGy), mean doses for brain stem, eye, and eye lens were 23.2, 34.2, and 37.6 mGy, respectively. For pediatric head scans (CTDIvol =35.6 mGy), mean doses for brain stem, eye, and eye lens were 19.3, 24.5, and 26.8 mGy, respectively. For adult chest scans (CTDIvol=19.0 mGy), mean doses for lung, heart, and spinal cord were 21.1, 22.0, and 15.5 mGy, respectively. For adult abdominal scans (CTDIvol=14.4 mGy), the mean doses for kidney, liver, pancreas, spleen, and spinal cord were 17.4, 16.5, 16.8, 16.8, and 13.1 mGy, respectively. For pediatric abdominal scans (CTDIvol=6.76 mGy), mean doses for kidney, liver, pancreas, spleen, and spinal cord were 8.24, 8.90, 8.17, 8.31, and 6.73 mGy, respectively. In head scan, organ doses were considerably different from CTDIvol values. Conclusion: MC dose distributions calculated by using patient CT images are useful to evaluate organ doses absorbed to individual patients.

  1. Model-based dose calculations for {sup 125}I lung brachytherapy

    SciTech Connect

    Sutherland, J. G. H.; Furutani, K. M.; Garces, Y. I.; Thomson, R. M.

    2012-07-15

    Purpose: Model-baseddose calculations (MBDCs) are performed using patient computed tomography (CT) data for patients treated with intraoperative {sup 125}I lung brachytherapy at the Mayo Clinic Rochester. Various metallic artifact correction and tissue assignment schemes are considered and their effects on dose distributions are studied. Dose distributions are compared to those calculated under TG-43 assumptions. Methods: Dose distributions for six patients are calculated using phantoms derived from patient CT data and the EGSnrc user-code BrachyDose. {sup 125}I (GE Healthcare/Oncura model 6711) seeds are fully modeled. Four metallic artifact correction schemes are applied to the CT data phantoms: (1) no correction, (2) a filtered back-projection on a modified virtual sinogram, (3) the reassignment of CT numbers above a threshold in the vicinity of the seeds, and (4) a combination of (2) and (3). Tissue assignment is based on voxel CT number and mass density is assigned using a CT number to mass density calibration. Three tissue assignment schemes with varying levels of detail (20, 11, and 5 tissues) are applied to metallic artifact corrected phantoms. Simulations are also performed under TG-43 assumptions, i.e., seeds in homogeneous water with no interseed attenuation. Results: Significant dose differences (up to 40% for D{sub 90}) are observed between uncorrected and metallic artifact corrected phantoms. For phantoms created with metallic artifact correction schemes (3) and (4), dose volume metrics are generally in good agreement (less than 2% differences for all patients) although there are significant local dose differences. The application of the three tissue assignment schemes results in differences of up to 8% for D{sub 90}; these differences vary between patients. Significant dose differences are seen between fully modeled and TG-43 calculations with TG-43 underestimating the dose (up to 36% in D{sub 90}) for larger volumes containing higher proportions of

  2. Estimates of Columbia River radionuclide concentrations: Data for Phase 1 dose calculations

    SciTech Connect

    Richmond, M.C.; Walters, W.H.

    1991-05-01

    Pacific Northwest Laboratory is conducting the Hanford Environmental Dose Reconstruction Project to estimate the radiation doses people may have received from historical Hanford Site operations. Under the direction of an independent Technical Steering Panel, the project is being conducted in phases. The objective of the first phase is to assess the feasibility of the project-wide technical approach for acquiring data and developing models needed to calculate potential radiation doses. This report summarizes data that were generated for the Phase 1 dose calculations. These included monthly average concentrations of specific radionuclides in Columbia River water and sediments between Priest Rapids Dam and McNary Dam for the years 1964 to 1966. Nine key radionuclides were selected for analysis based on estimation of their contribution to dose. Concentrations of these radionuclides in the river were estimated using existing measurements and hydraulic calculations based on the simplifying assumption that dilution and decay were the primary processes controlling the fate of radionuclides released to the river. Five sub-reaches between Priest Rapids Dam and McNary Dam, corresponding to population centers and tributary confluences, were identified and monthly average radionuclide concentrations were calculated for each sub-reach. The hydraulic calculations were performed to provide radionuclide concentration estimates for time periods and geographic locations where measured data were not available. The validity of the calculation method will be evaluated in Phase 2. 12 refs., 13 figs., 49 tabs.

  3. Monte Carlo calculation of dose to water of a 106Ru COB-type ophthalmic plaque

    NASA Astrophysics Data System (ADS)

    Šolc, J.

    2008-02-01

    The concave eye applicators with 106Ru/106Rh or 90Sr/90Y beta-ray sources are worldwide used in brachytherapy for treating intraocular tumors. It raises the need to know the exact dose delivered by beta radiation to tumors but measurement of the dose to water (or tissue) is very difficult due to short range of electrons. The Monte Carlo technique provides a powerful tool for calculation of the dose and dose distributions which helps to predict and determine the doses from different shapes of various types of eye applicators more accurately. The Monte Carlo code MCNPX has been used to calculate dose distributions from a COB-type 106Ru/106Rh ophthalmic applicator manufactured by Eckert & Ziegler BEBIG GmbH. This type of a concave eye applicator has a cut-out whose purpose is to protect the eye nerve which makes the dose distribution more complicated. Several calculations have been performed including depth dose along the applicator central axis and various dose distributions. The depth dose along the applicator central axis and the dose distribution on a spherical surface 1 mm above the plaque inner surface have been compared with measurement data provided by the manufacturer. For distances from 0.5 to 4 mm above the surface, the agreement was within 2.5 % and from 5 mm the difference increased from 6 % up to 25 % at 10 mm whereas the uncertainty on manufacturer data is 20 % (2s). It is assumed that the difference is caused by nonuniformly distributed radioactivity over the applicator radioactive layer.

  4. Quantification of the impact of MLC modeling and tissue heterogeneities on dynamic IMRT dose calculations

    SciTech Connect

    Mihaylov, I. B.; Lerma, F. A.; Fatyga, M.; Siebers, J. V.

    2007-04-15

    This study quantifies the dose prediction errors (DPEs) in dynamic IMRT dose calculations resulting from (a) use of an intensity matrix to estimate the multi-leaf collimator (MLC) modulated photon fluence (DPE{sub IGfluence}) instead of an explicit MLC particle transport, and (b) handling of tissue heterogeneities (DPE{sub hetero}) by superposition/convolution (SC) and pencil beam (PB) dose calculation algorithms. Monte Carlo (MC) computed doses are used as reference standards. Eighteen head-and-neck dynamic MLC IMRT treatment plans are investigated. DPEs are evaluated via comparing the dose received by 98% of the GTV (GTV D{sub 98%}), the CTV D{sub 95%}, the nodal D{sub 90%}, the cord and the brainstem D{sub 02%}, the parotid D{sub 50%}, the parotid mean dose (D{sub Mean}), and generalized equivalent uniform doses (gEUDs) for the above structures. For the MC-generated intensity grids, DPE{sub IGfluence} is within {+-}2.1% for all targets and critical structures. The SC algorithm DPE{sub hetero} is within {+-}3% for 98.3% of the indices tallied, and within {+-}3.4% for all of the tallied indices. The PB algorithm DPE{sub hetero} is within {+-}3% for 92% of the tallied indices. Statistical equivalence tests indicate that PB DPE{sub hetero} requires a {+-}3.6% interval to state equivalence with the MC standard, while the intervals are <1.5% for SC DPE{sub hetero} and DPE{sub IGfluence}. Overall, these results indicate that SC and MC IMRT dose calculations which use MC-derived intensity matrices for fluence prediction do not introduce significant dose errors compared with full Monte Carlo dose computations; however, PB algorithms may result in clinically significant dose deviations.

  5. Evaluation of an electron Monte Carlo dose calculation algorithm for treatment planning.

    PubMed

    Chamberland, Eve; Beaulieu, Luc; Lachance, Bernard

    2015-01-01

    The purpose of this study is to evaluate the accuracy of the electron Monte Carlo (eMC) dose calculation algorithm included in a commercial treatment planning system and compare its performance against an electron pencil beam algorithm. Several tests were performed to explore the system's behavior in simple geometries and in configurations encountered in clinical practice. The first series of tests were executed in a homogeneous water phantom, where experimental measurements and eMC-calculated dose distributions were compared for various combinations of energy and applicator. More specifically, we compared beam profiles and depth-dose curves at different source-to-surface distances (SSDs) and gantry angles, by using dose difference and distance to agreement. Also, we compared output factors, we studied the effects of algorithm input parameters, which are the random number generator seed, as well as the calculation grid size, and we performed a calculation time evaluation. Three different inhomogeneous solid phantoms were built, using high- and low-density materials inserts, to clinically simulate relevant heterogeneity conditions: a small air cylinder within a homogeneous phantom, a lung phantom, and a chest wall phantom. We also used an anthropomorphic phantom to perform comparison of eMC calculations to measurements. Finally, we proceeded with an evaluation of the eMC algorithm on a clinical case of nose cancer. In all mentioned cases, measurements, carried out by means of XV-2 films, radiographic films or EBT2 Gafchromic films. were used to compare eMC calculations with dose distributions obtained from an electron pencil beam algorithm. eMC calculations in the water phantom were accurate. Discrepancies for depth-dose curves and beam profiles were under 2.5% and 2 mm. Dose calculations with eMC for the small air cylinder and the lung phantom agreed within 2% and 4%, respectively. eMC calculations for the chest wall phantom and the anthropomorphic phantom also

  6. The impact of photon dose calculation algorithms on expected dose distributions in lungs under different respiratory phases

    NASA Astrophysics Data System (ADS)

    Fogliata, Antonella; Nicolini, Giorgia; Vanetti, Eugenio; Clivio, Alessandro; Winkler, Peter; Cozzi, Luca

    2008-05-01

    A planning study was carried out on a cohort of CT datasets from breast patients scanned during different respiratory phases. The aim of the study was to investigate the influence of different air filling in lungs on the calculation accuracy of photon dose algorithms and to identify potential patterns of failure with clinical implications. Selected respiratory phases were free breathing (FB), representative of typical end expiration, and deep inspiration breath hold (DIBH), a typical condition for clinical treatment with respiratory gating. Algorithms investigated were the pencil beam (PBC), the anisotropic analytical algorithm (AAA) and the collapsed cone (CC) from the Varian Eclipse or Philips Pinnacle planning system. Reference benchmark calculations were performed with the Voxel Monte Carlo (VMC++). An analysis was performed in terms of physical quantities inspecting either dose-volume or dose-mass histograms and in terms of an extension to three dimensions of the γ index of Low. Results were stratified according to a breathing phase and algorithm. Collectives acquired in FB or DIBH showed well-separated average lung density distributions with mean densities of 0.27 ± 0.04 and 0.16 ± 0.02 g cm-3, respectively, and average peak densities of 0.17 ± 0.03 and 0.09 ± 0.02 g cm-3. Analysis of volume-dose or mass-dose histograms proved the expected deviations on PBC results due to the missing lateral transport of electrons with underestimations in the low dose region and overestimations in the high dose region. From the γ analysis, it resulted that PBC is systematically defective compared to VMC++ over the entire range of lung densities and dose levels with severe violations in both respiratory phases. The fraction of lung voxels with γ > 1 for PBC reached 25% in DIBH and about 15% in FB. CC and AAA performed, in contrast, similarly and with fractions of lung voxels with γ > 1 in average inferior to 2% in FB and 4-5% (AAA) or 6-8% (CC) in DIBH. In summary, PBC

  7. Dose calculations using convolution and superposition principles: the orientation of dose spread kernels in divergent x-ray beams.

    PubMed

    Sharpe, M B; Battista, J J

    1993-01-01

    The convolution/superposition method of dose calculation has the potential to become the preferred technique for radiotherapy treatment planning. When this approach is used for therapeutic x-ray beams, the dose spread kernels are usually aligned parallel to the central axis of the incident beam. While this reduces the computational burden, it is more rigorous to tilt the kernel axis to align it with the diverging beam rays that define the incident direction of primary photons. We have assessed the validity of the parallel kernel approximation by computing dose distributions using parallel and tilted kernels for monoenergetic photons of 2, 6, and 10 MeV; source-to-surface distances (SSDs) of 50, 80, and 100 cm; and for field sizes of 5 x 5, 15 x 15, and 30 x 30 cm2. Over most of the irradiated volume, the parallel kernel approximation yields results that differ from tilted kernel calculations by 3% or less for SSDs greater than 80 cm. Under extreme conditions of a short SSD, a large field size and high incident photon energy, the parallel kernel approximation results in discrepancies that may be clinically unacceptable. For 10-MeV photons, we have observed that the parallel kernel approximation can overestimate the dose by up to 4.4% of the maximum on the central axis for a field size of 30 x 30 cm2 applied with a SSD of 50 cm. Very localized dose underestimations of up to 27% of the maximum dose occurred in the penumbral region of a 30 x 30-cm2 field of 10-MeV photons applied with a SSD of 50 cm. PMID:8309441

  8. Impact of dose calculation accuracy during optimization on lung IMRT plan quality.

    PubMed

    Li, Ying; Rodrigues, Anna; Li, Taoran; Yuan, Lulin; Yin, Fang-Fang; Wu, Q Jackie

    2015-01-01

    The purpose of this study was to evaluate the effect of dose calculation accuracy and the use of an intermediate dose calculation step during the optimization of intensity-modulated radiation therapy (IMRT) planning on the final plan quality for lung cancer patients. This study included replanning for 11 randomly selected free-breathing lung IMRT plans. The original plans were optimized using a fast pencil beam convolution algorithm. After optimization, the final dose calculation was performed using the analytical anisotropic algorithm (AAA). The Varian Treatment Planning System (TPS) Eclipse v11, includes an option to perform intermediate dose calculation during optimization using the AAA. The new plans were created using this intermediate dose calculation during optimization with the same planning objectives and dose constraints as in the original plan. Differences in dosimetric parameters for the planning target volume (PTV) dose coverage, organs-at-risk (OARs) dose sparing, and the number of monitor units (MU) between the original and new plans were analyzed. Statistical significance was determined with a p-value of less than 0.05. All plans were normalized to cover 95% of the PTV with the prescription dose. Compared with the original plans, the PTV in the new plans had on average a lower maximum dose (69.45 vs. 71.96Gy, p = 0.005), a better homogeneity index (HI) (0.08 vs. 0.12, p = 0.002), and a better conformity index (CI) (0.69 vs. 0.59, p = 0.003). In the new plans, lung sparing was increased as the volumes receiving 5, 10, and 30 Gy were reduced when compared to the original plans (40.39% vs. 42.73%, p = 0.005; 28.93% vs. 30.40%, p = 0.001; 14.11%vs. 14.84%, p = 0.031). The volume receiving 20 Gy was not significantly lower (19.60% vs. 20.38%, p = 0.052). Further, the mean dose to the lung was reduced in the new plans (11.55 vs. 12.12 Gy, p = 0.024). For the esophagus, the mean dose, the maximum dose, and the volumes receiving 20 and 60 Gy were lower in

  9. Postimplant Dosimetry Using a Monte Carlo Dose Calculation Engine: A New Clinical Standard

    SciTech Connect

    Carrier, Jean-Francois . E-mail: jean-francois.carrier.chum@ssss.gouv.qc.ca; D'Amours, Michel; Verhaegen, Frank; Reniers, Brigitte; Martin, Andre-Guy; Vigneault, Eric; Beaulieu, Luc

    2007-07-15

    Purpose: To use the Monte Carlo (MC) method as a dose calculation engine for postimplant dosimetry. To compare the results with clinically approved data for a sample of 28 patients. Two effects not taken into account by the clinical calculation, interseed attenuation and tissue composition, are being specifically investigated. Methods and Materials: An automated MC program was developed. The dose distributions were calculated for the target volume and organs at risk (OAR) for 28 patients. Additional MC techniques were developed to focus specifically on the interseed attenuation and tissue effects. Results: For the clinical target volume (CTV) D{sub 90} parameter, the mean difference between the clinical technique and the complete MC method is 10.7 Gy, with cases reaching up to 17 Gy. For all cases, the clinical technique overestimates the deposited dose in the CTV. This overestimation is mainly from a combination of two effects: the interseed attenuation (average, 6.8 Gy) and tissue composition (average, 4.1 Gy). The deposited dose in the OARs is also overestimated in the clinical calculation. Conclusions: The clinical technique systematically overestimates the deposited dose in the prostate and in the OARs. To reduce this systematic inaccuracy, the MC method should be considered in establishing a new standard for clinical postimplant dosimetry and dose-outcome studies in a near future.

  10. Beta dose calculation in human arteries for various brachytherapy seed types

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Woo

    This dissertation explores beta dose profile of microspheres packed in arteries, various source geometries of 142Pr that can be used for therapeutic purpose, and dose backscatter factors for selected beta sources. A novel treatment method by injecting microspheres into feeding arteries of arteriovenous malformation (AVM) is under pre-clinical investigation. To optimize radiation dose to the clinically important area, i.e. arterial wall, preliminary dosimetric studies were needed. Monte Carlo calculations were performed for several geometries simulating arteries filled with microspheres packed by random packing methods. Arterial radii used in the simulation varied from 50 mum to 3 mm; microsphere radii varied from 10 mum to 0.7 mm. Dose varied significantly as a function of microsphere size, for constant arterial sizes. For the same sizes of arteries, significant dose increase was observed because of inter-artery exposure for large arteries (>0.1 cm rad.) filled with large microspheres (>0.03 cm rad.). Dose increase between small arteries (<0.03 cm rad.) was less significant. The dose profiles of prototype 142Pr beta brachytherapy sources were calculated using MCNP 4C Monte Carlo code as well as dose point kernel (DPK) for selected cases. Dose profiles were similar to beta sources currently used indicating that 142Pr can substitute for current sources for certain cases and the DPK was closely matched with MCNP result. Backscattering of electrons is a prominent secondary effect in beta dosimetry. The backscattering is closely correlated with factors such as geometry of source and scattering material, and composition of scattering material. The backscattering factors were calculated for selected beta sources that are currently used as well as potentially useful sources for therapeutic purpose. The factors were calculated as a function of distance from the interface between water and scatterers. These factors were fit by a simple function for future incorporation into

  11. SU-E-T-161: Evaluation of Dose Calculation Based On Cone-Beam CT

    SciTech Connect

    Abe, T; Nakazawa, T; Saitou, Y; Nakata, A; Yano, M; Tateoka, K; Fujimoto, K; Sakata, K

    2014-06-01

    Purpose: The purpose of this study is to convert pixel values in cone-beam CT (CBCT) using histograms of pixel values in the simulation CT (sim-CT) and the CBCT images and to evaluate the accuracy of dose calculation based on the CBCT. Methods: The sim-CT and CBCT images immediately before the treatment of 10 prostate cancer patients were acquired. Because of insufficient calibration of the pixel values in the CBCT, it is difficult to be directly used for dose calculation. The pixel values in the CBCT images were converted using an in-house program. A 7 fields treatment plans (original plan) created on the sim-CT images were applied to the CBCT images and the dose distributions were re-calculated with same monitor units (MUs). These prescription doses were compared with those of original plans. Results: In the results of the pixel values conversion in the CBCT images,the mean differences of pixel values for the prostate,subcutaneous adipose, muscle and right-femur were −10.78±34.60, 11.78±41.06, 29.49±36.99 and 0.14±31.15 respectively. In the results of the calculated doses, the mean differences of prescription doses for 7 fields were 4.13±0.95%, 0.34±0.86%, −0.05±0.55%, 1.35±0.98%, 1.77±0.56%, 0.89±0.69% and 1.69±0.71% respectively and as a whole, the difference of prescription dose was 1.54±0.4%. Conclusion: The dose calculation on the CBCT images achieve an accuracy of <2% by using this pixel values conversion program. This may enable implementation of efficient adaptive radiotherapy.

  12. SU-E-T-27: A Tool for Routine Quality Assurance of Radiotherapy Dose Calculation Software

    SciTech Connect

    Popple, R; Cardan, R; Duan, J; Wu, X; Shen, S; Brezovich, I

    2014-06-01

    Purpose: Dose calculation software is thoroughly evaluated when it is commissioned; however, evaluation of periodic software updates is typically limited in scope due to staffing constraints and the need to quickly return the treatment planning system to clinical service. We developed a tool for quickly and comprehensively testing and documenting dose calculation software against measured data. Methods: A tool was developed using MatLab (The MathWorks, Natick, MA) for evaluation of dose calculation algorithms against measured data. Inputs to the tool are measured data, reference DICOM RT PLAN files describing the measurements, and dose calculations in DICOM format. The tool consists of a collection of extensible modules that can perform analysis of point dose, depth dose curves, and profiles using dose difference, distance-to-agreement, and the gamma-index. Each module generates a report subsection that is incorporated into a master template, which is converted to final form in portable document format (PDF). Results: After each change to the treatment planning system, a report can be generated in approximately 90 minutes. The tool has been in use for more than 5 years, spanning 5 versions of the eMC and 4 versions of the AAA. We have detected changes to the algorithms that affected clinical practice once during this period. Conclusion: Our tool provides an efficient method for quality assurance of dose calculation software, providing a complete set of tests for an update. Future work includes the addition of plan level tests, allowing incorporation of, for example, the TG-119 test suite for IMRT, and integration with the treatment planning system via an application programming interface. Integration with the planning system will permit fully-automated testing and reporting at scheduled intervals.

  13. Effect of dosimeter type for commissioning small photon beams on calculated dose distribution in stereotactic radiosurgery

    SciTech Connect

    García-Garduño, O. A. E-mail: amanda.garcia.g@gmail.com; Rodríguez-Ponce, M.; Gamboa-deBuen, I.; Rodríguez-Villafuerte, M.; Galván de la Cruz, O. O.; and others

    2014-09-15

    Purpose: To assess the impact of the detector used to commission small photon beams on the calculated dose distribution in stereotactic radiosurgery (SRS). Methods: In this study, six types of detectors were used to characterize small photon beams: three diodes [a silicon stereotactic field diode SFD, a silicon diode SRS, and a silicon diode E], an ionization chamber CC01, and two types of radiochromic film models EBT and EBT2. These detectors were used to characterize circular collimated beams that were generated by a Novalis linear accelerator. This study was conducted in two parts. First, the following dosimetric data, which are of particular interest in SRS, were compared for the different detectors: the total scatter factor (TSF), the tissue phantom ratios (TPRs), and the off-axis ratios (OARs). Second, the commissioned data sets were incorporated into the treatment planning system (TPS) to compare the calculated dose distributions and the dose volume histograms (DVHs) that were obtained using the different detectors. Results: The TSFs data measured by all of the detectors were in good agreement with each other within the respective statistical uncertainties: two exceptions, where the data were systematically below those obtained for the other detectors, were the CC01 results for all of the circular collimators and the EBT2 film results for circular collimators with diameters below 10.0 mm. The OAR results obtained for all of the detectors were in excellent agreement for all of the circular collimators. This observation was supported by the gamma-index test. The largest difference in the TPR data was found for the 4.0 mm circular collimator, followed by the 10.0 and 20.0 mm circular collimators. The results for the calculated dose distributions showed that all of the detectors passed the gamma-index test at 100% for the 3 mm/3% criteria. The aforementioned observation was true regardless of the size of the calculation grid for all of the circular collimators

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

    PubMed

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

    2009-04-01

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

  15. An energy transfer method for 4D Monte Carlo dose calculation

    PubMed Central

    Siebers, Jeffrey V.; Zhong, Hualiang

    2008-01-01

    This article presents a new method for four-dimensional Monte Carlo dose calculations which properly addresses dose mapping for deforming anatomy. The method, called the energy transfer method (ETM), separates the particle transport and particle scoring geometries: Particle transport takes place in the typical rectilinear coordinate system of the source image, while energy deposition scoring takes place in a desired reference image via use of deformable image registration. Dose is the energy deposited per unit mass in the reference image. ETM has been implemented into DOSXYZnrc and compared with a conventional dose interpolation method (DIM) on deformable phantoms. For voxels whose contents merge in the deforming phantom, the doses calculated by ETM are exactly the same as an analytical solution, contrasting to the DIM which has an average 1.1% dose discrepancy in the beam direction with a maximum error of 24.9% found in the penumbra of a 6 MV beam. The DIM error observed persists even if voxel subdivision is used. The ETM is computationally efficient and will be useful for 4D dose addition and benchmarking alternative 4D dose addition algorithms. PMID:18841862

  16. An energy transfer method for 4D Monte Carlo dose calculation.

    PubMed

    Siebers, Jeffrey V; Zhong, Hualiang

    2008-09-01

    This article presents a new method for four-dimensional Monte Carlo dose calculations which properly addresses dose mapping for deforming anatomy. The method, called the energy transfer method (ETM), separates the particle transport and particle scoring geometries: Particle transport takes place in the typical rectilinear coordinate system of the source image, while energy deposition scoring takes place in a desired reference image via use of deformable image registration. Dose is the energy deposited per unit mass in the reference image. ETM has been implemented into DOSXYZnrc and compared with a conventional dose interpolation method (DIM) on deformable phantoms. For voxels whose contents merge in the deforming phantom, the doses calculated by ETM are exactly the same as an analytical solution, contrasting to the DIM which has an average 1.1% dose discrepancy in the beam direction with a maximum error of 24.9% found in the penumbra of a 6 MV beam. The DIM error observed persists even if voxel subdivision is used. The ETM is computationally efficient and will be useful for 4D dose addition and benchmarking alternative 4D dose addition algorithms. PMID:18841862

  17. The 2002 dosimetry system (DS02) and available fluences for organ dose calculations.

    PubMed

    Egbert, Stephen D

    2012-03-01

    The A bomb dosimetry system (DS) calculates each survivor's organ doses. It does this by calculating the angular fluences incident on each survivor. These are used with humanoid phantom shielding calculations to estimate organ doses in 15 organs, 3-sized phantoms, 2 sexes and 2 postures at any orientation or distance to the bomb. The DS has been re-used and updated several times. Currently, efforts are being considered to include shielding for additional organs by adding additional phantoms. The DS has gone through a series of upgrades referred to as: DS84, DS86, DS86R, DS93, DS02. DS86 and DS02 were approved and installed at Radiation Effects Research Foundation. The system uses free-field energy-angular fluence from a discrete ordinate calculation coupled with Monte Carlo adjoint-shielding histories. This paper briefly discusses the adjoint Monte Carlo; combinatorial shield geometry for the phantom, house, factory, and terrain; modifications to use fictitious scattering in voxel phantoms; the adjoint source energy, angle and location distribution; 'leakage histories' and their optimisation for dose or fluence; doubly differential (energy-angle) coupling for single-, double-, or triple-shielding coupling; output of various components of dose and energy-angular fluences; survivor-specific inputs; organ dose uncertainty; and testing, benchmarking and extended applications. Also, approaches to add additional organ-shielding calculations to DS02 are discussed. PMID:21778157

  18. Review of Fast Monte Carlo Codes for Dose Calculation in Radiation Therapy Treatment Planning

    PubMed Central

    Jabbari, Keyvan

    2011-01-01

    An important requirement in radiation therapy is a fast and accurate treatment planning system. This system, using computed tomography (CT) data, direction, and characteristics of the beam, calculates the dose at all points of the patient's volume. The two main factors in treatment planning system are accuracy and speed. According to these factors, various generations of treatment planning systems are developed. This article is a review of the Fast Monte Carlo treatment planning algorithms, which are accurate and fast at the same time. The Monte Carlo techniques are based on the transport of each individual particle (e.g., photon or electron) in the tissue. The transport of the particle is done using the physics of the interaction of the particles with matter. Other techniques transport the particles as a group. For a typical dose calculation in radiation therapy the code has to transport several millions particles, which take a few hours, therefore, the Monte Carlo techniques are accurate, but slow for clinical use. In recent years, with the development of the ‘fast’ Monte Carlo systems, one is able to perform dose calculation in a reasonable time for clinical use. The acceptable time for dose calculation is in the range of one minute. There is currently a growing interest in the fast Monte Carlo treatment planning systems and there are many commercial treatment planning systems that perform dose calculation in radiation therapy based on the Monte Carlo technique. PMID:22606661

  19. SU-E-T-202: Impact of Monte Carlo Dose Calculation Algorithm On Prostate SBRT Treatments

    SciTech Connect

    Venencia, C; Garrigo, E; Cardenas, J; Castro Pena, P

    2014-06-01

    Purpose: The purpose of this work was to quantify the dosimetric impact of using Monte Carlo algorithm on pre calculated SBRT prostate treatment with pencil beam dose calculation algorithm. Methods: A 6MV photon beam produced by a Novalis TX (BrainLAB-Varian) linear accelerator equipped with HDMLC was used. Treatment plans were done using 9 fields with Iplanv4.5 (BrainLAB) and dynamic IMRT modality. Institutional SBRT protocol uses a total dose to the prostate of 40Gy in 5 fractions, every other day. Dose calculation is done by pencil beam (2mm dose resolution), heterogeneity correction and dose volume constraint (UCLA) for PTV D95%=40Gy and D98%>39.2Gy, Rectum V20Gy<50%, V32Gy<20%, V36Gy<10% and V40Gy<5%, Bladder V20Gy<40% and V40Gy<10%, femoral heads V16Gy<5%, penile bulb V25Gy<3cc, urethra and overlap region between PTV and PRV Rectum Dmax<42Gy. 10 SBRT treatments plans were selected and recalculated using Monte Carlo with 2mm spatial resolution and mean variance of 2%. DVH comparisons between plans were done. Results: The average difference between PTV doses constraints were within 2%. However 3 plans have differences higher than 3% which does not meet the D98% criteria (>39.2Gy) and should have been renormalized. Dose volume constraint differences for rectum, bladder, femoral heads and penile bulb were les than 2% and within tolerances. Urethra region and overlapping between PTV and PRV Rectum shows increment of dose in all plans. The average difference for urethra region was 2.1% with a maximum of 7.8% and for the overlapping region 2.5% with a maximum of 8.7%. Conclusion: Monte Carlo dose calculation on dynamic IMRT treatments could affects on plan normalization. Dose increment in critical region of urethra and PTV overlapping region with PTV could have clinical consequences which need to be studied. The use of Monte Carlo dose calculation algorithm is limited because inverse planning dose optimization use only pencil beam.

  20. Radiation dose calculations for CT scans with tube current modulation using the approach to equilibrium function

    SciTech Connect

    Li, Xinhua; Zhang, Da; Liu, Bob

    2014-11-01

    Purpose: The approach to equilibrium function has been used previously to calculate the radiation dose to a shift-invariant medium undergoing CT scans with constant tube current [Li, Zhang, and Liu, Med. Phys. 39, 5347–5352 (2012)]. The authors have adapted this method to CT scans with tube current modulation (TCM). Methods: For a scan with variable tube current, the scan range was divided into multiple subscan ranges, each with a nearly constant tube current. Then the dose calculation algorithm presented previously was applied. For a clinical CT scan series that presented tube current per slice, the authors adopted an efficient approach that computed the longitudinal dose distribution for one scan length equal to the slice thickness, which center was at z = 0. The cumulative dose at a specific point was a summation of the contributions from all slices and the overscan. Results: The dose calculations performed for a total of four constant and variable tube current distributions agreed with the published results of Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)]. For an abdomen/pelvis scan of an anthropomorphic phantom (model ATOM 701-B, CIRS, Inc., VA) on a GE Lightspeed Pro 16 scanner with 120 kV, N × T = 20 mm, pitch = 1.375, z axis current modulation (auto mA), and angular current modulation (smart mA), dose measurements were performed using two lines of optically stimulated luminescence dosimeters, one of which was placed near the phantom center and the other on the surface. Dose calculations were performed on the central and peripheral axes of a cylinder containing water, whose cross-sectional mass was about equal to that of the ATOM phantom in its abdominal region, and the results agreed with the measurements within 28.4%. Conclusions: The described method provides an effective approach that takes into account subject size, scan length, and constant or variable tube current to evaluate CT dose to a shift-invariant medium. For a clinical CT scan

  1. Monte Carlo dose calculation improvements for low energy electron beams using eMC.

    PubMed

    Fix, Michael K; Frei, Daniel; Volken, Werner; Neuenschwander, Hans; Born, Ernst J; Manser, Peter

    2010-08-21

    The electron Monte Carlo (eMC) dose calculation algorithm in Eclipse (Varian Medical Systems) is based on the macro MC method and is able to predict dose distributions for high energy electron beams with high accuracy. However, there are limitations for low energy electron beams. This work aims to improve the accuracy of the dose calculation using eMC for 4 and 6 MeV electron beams of Varian linear accelerators. Improvements implemented into the eMC include (1) improved determination of the initial electron energy spectrum by increased resolution of mono-energetic depth dose curves used during beam configuration; (2) inclusion of all the scrapers of the applicator in the beam model; (3) reduction of the maximum size of the sphere to be selected within the macro MC transport when the energy of the incident electron is below certain thresholds. The impact of these changes in eMC is investigated by comparing calculated dose distributions for 4 and 6 MeV electron beams at source to surface distance (SSD) of 100 and 110 cm with applicators ranging from 6 x 6 to 25 x 25 cm(2) of a Varian Clinac 2300C/D with the corresponding measurements. Dose differences between calculated and measured absolute depth dose curves are reduced from 6% to less than 1.5% for both energies and all applicators considered at SSD of 100 cm. Using the original eMC implementation, absolute dose profiles at depths of 1 cm, d(max) and R50 in water lead to dose differences of up to 8% for applicators larger than 15 x 15 cm(2) at SSD 100 cm. Those differences are now reduced to less than 2% for all dose profiles investigated when the improved version of eMC is used. At SSD of 110 cm the dose difference for the original eMC version is even more pronounced and can be larger than 10%. Those differences are reduced to within 2% or 2 mm with the improved version of eMC. In this work several enhancements were made in the eMC algorithm leading to significant improvements in the accuracy of the dose

  2. The Multi-Step CADIS method for shutdown dose rate calculations and uncertainty propagation

    DOE PAGESBeta

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

    2015-12-01

    Shutdown dose rate (SDDR) analysis requires (a) a neutron transport calculation to estimate neutron flux fields, (b) an activation calculation to compute radionuclide inventories and associated photon sources, and (c) a photon transport calculation to estimate final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for very large systems with massive amounts of shielding materials. However, these simulations are impractical because calculation of space- and energy-dependent neutron fluxes throughout the structural materials is needed to estimate distribution of radioisotopes causing the SDDR. Biasing the neutron MC calculation using an importance function is not simple becausemore » it is difficult to explicitly express the response function, which depends on subsequent computational steps. Furthermore, the typical SDDR calculations do not consider how uncertainties in MC neutron calculation impact SDDR uncertainty, even though MC neutron calculation uncertainties usually dominate SDDR uncertainty.« less

  3. The Multi-Step CADIS method for shutdown dose rate calculations and uncertainty propagation

    SciTech Connect

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

    2015-12-01

    Shutdown dose rate (SDDR) analysis requires (a) a neutron transport calculation to estimate neutron flux fields, (b) an activation calculation to compute radionuclide inventories and associated photon sources, and (c) a photon transport calculation to estimate final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for very large systems with massive amounts of shielding materials. However, these simulations are impractical because calculation of space- and energy-dependent neutron fluxes throughout the structural materials is needed to estimate distribution of radioisotopes causing the SDDR. Biasing the neutron MC calculation using an importance function is not simple because it is difficult to explicitly express the response function, which depends on subsequent computational steps. Furthermore, the typical SDDR calculations do not consider how uncertainties in MC neutron calculation impact SDDR uncertainty, even though MC neutron calculation uncertainties usually dominate SDDR uncertainty.

  4. Dose Rate Calculations for the 2-MCO/2-DHLW Waste Package

    SciTech Connect

    G. Radulescu

    2000-10-03

    The objective of this calculation is to determine the dose rates on the external surfaces of the waste package (WP) containing two Hanford defense high-level waste (DHLW) glass canisters and two Hanford multi-canister overpacks (MCO). Each MCO is loaded with the N Reactor spent nuclear fuel (SNF). The information provided by the sketches attached to this calculation is that of the potential design for the WP type considered in this calculation. The scope of this calculation is limited to reporting dose rates averaged over segments of the WP radial and axial surfaces and of surfaces 1 m and 2 m from the WP. The results of this calculation will be used to assess the shielding performance of the 2-MC012-DHLW WP engineering design.

  5. Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom

    SciTech Connect

    Lesperance, Marielle; Inglis-Whalen, M.; Thomson, R. M.

    2014-02-15

    Purpose : To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with{sup 125}I, {sup 103}Pd, or {sup 131}Cs seeds, and to investigate doses to ocular structures. Methods : An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Results : Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20–30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%–10% and 13%–14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%–17% and 29%–34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model

  6. Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme

    SciTech Connect

    Zasneda, Sabriani; Widita, Rena

    2010-06-22

    Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, {alpha}) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg {sup 10}B/g blood.

  7. Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme

    NASA Astrophysics Data System (ADS)

    Zasneda, Sabriani; Widita, Rena

    2010-06-01

    Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, α) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg 10B/g blood.

  8. Calculation of radiation therapy dose using all particle Monte Carlo transport

    DOEpatents

    Chandler, W.P.; Hartmann-Siantar, C.L.; Rathkopf, J.A.

    1999-02-09

    The actual radiation dose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimate dose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media. 57 figs.

  9. Calculation of radiation therapy dose using all particle Monte Carlo transport

    DOEpatents

    Chandler, William P.; Hartmann-Siantar, Christine L.; Rathkopf, James A.

    1999-01-01

    The actual radiation dose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimate dose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media.

  10. Comprehensive evaluation and clinical implementation of commercially available Monte Carlo dose calculation algorithm.

    PubMed

    Zhang, Aizhen; Wen, Ning; Nurushev, Teamour; Burmeister, Jay; Chetty, Indrin J

    2013-01-01

    A commercial electron Monte Carlo (eMC) dose calculation algorithm has become available in Eclipse treatment planning system. The purpose of this work was to evaluate the eMC algorithm and investigate the clinical implementation of this system. The beam modeling of the eMC algorithm was performed for beam energies of 6, 9, 12, 16, and 20 MeV for a Varian Trilogy and all available applicator sizes in the Eclipse treatment planning system. The accuracy of the eMC algorithm was evaluated in a homogeneous water phantom, solid water phantoms containing lung and bone materials, and an anthropomorphic phantom. In addition, dose calculation accuracy was compared between pencil beam (PB) and eMC algorithms in the same treatment planning system for heterogeneous phantoms. The overall agreement between eMC calculations and measurements was within 3%/2 mm, while the PB algorithm had large errors (up to 25%) in predicting dose distributions in the presence of inhomogeneities such as bone and lung. The clinical implementation of the eMC algorithm was investigated by performing treatment planning for 15 patients with lesions in the head and neck, breast, chest wall, and sternum. The dose distributions were calculated using PB and eMC algorithms with no smoothing and all three levels of 3D Gaussian smoothing for comparison. Based on a routine electron beam therapy prescription method, the number of eMC calculated monitor units (MUs) was found to increase with increased 3D Gaussian smoothing levels. 3D Gaussian smoothing greatly improved the visual usability of dose distributions and produced better target coverage. Differences of calculated MUs and dose distributions between eMC and PB algorithms could be significant when oblique beam incidence, surface irregularities, and heterogeneous tissues were present in the treatment plans. In our patient cases, monitor unit differences of up to 7% were observed between PB and eMC algorithms. Monitor unit calculations were also preformed

  11. Monte Carlo-based dose calculation engine for minibeam radiation therapy.

    PubMed

    Martínez-Rovira, I; Sempau, J; Prezado, Y

    2014-02-01

    Minibeam radiation therapy (MBRT) is an innovative radiotherapy approach based on the well-established tissue sparing effect of arrays of quasi-parallel micrometre-sized beams. In order to guide the preclinical trials in progress at the European Synchrotron Radiation Facility (ESRF), a Monte Carlo-based dose calculation engine has been developed and successfully benchmarked with experimental data in anthropomorphic phantoms. Additionally, a realistic example of treatment plan is presented. Despite the micron scale of the voxels used to tally dose distributions in MBRT, the combination of several efficiency optimisation methods allowed to achieve acceptable computation times for clinical settings (approximately 2 h). The calculation engine can be easily adapted with little or no programming effort to other synchrotron sources or for dose calculations in presence of contrast agents. PMID:23597423

  12. Interpolation Method for Calculation of Computed Tomography Dose from Angular Varying Tube Current

    NASA Astrophysics Data System (ADS)

    Caracappa, Peter F.; Gao, Yiming; Xu, X. George

    2014-06-01

    The scope and magnitude of radiation dose from computed tomography (CT) examination has led to increased scrutiny and focus on accurate dose tracking. The use of tube current modulation (TCM) results complicates dose tracking by generating unique scans that are specific to the patient. Three methods of estimating the radiation dose from a CT examination that uses TCM are compared: using the average current for an entire scan, using the average current for each slice in the scan, and using an estimation of the angular variation of the dose contribution. To determine the impact of TCM on the radiation dose received, a set of angular weighting functions for each tissue of the body are derived by fitting a function to the relative dose contributions tabulated for the four principle exposure projections. This weighting function is applied to the angular tube current function to determine the organ dose contributions from a single rotation. Since the angular tube current function is not typically known, a method for estimating that function is also presented. The organ doses calculated using these three methods are compared to simulations that explicitly include the estimated TCM function.

  13. Dose Calculations for [131I] Meta-Iodobenzylguanidine-Induced Bystander Effects

    PubMed Central

    Gow, M. D.; Seymour, C. B.; Boyd, M.; Mairs, R. J.; Prestiwch, W. V.; Mothersill, C. E.

    2014-01-01

    Targeted radiotherapy is a potentially useful treatment for some cancers and may be potentiated by bystander effects. However, without estimation of absorbed dose, it is difficult to compare the effects with conventional external radiation treatment. Methods: Using the Vynckier – Wambersie dose point kernel, a model for dose rate evaluation was created allowing for calculation of absorbed dose values to two cell lines transfected with the noradrenaline transporter (NAT) gene and treated with [131I]MIBG. Results: The mean doses required to decrease surviving fractions of UVW/NAT and EJ138/NAT cells, which received medium from [131I]MIBG-treated cells, to 25 – 30% were 1.6 and 1.7 Gy respectively. The maximum mean dose rates achieved during [131I]MIBG treatment were 0.09 – 0.75 Gy/h for UVW/NAT and 0.07 – 0.78 Gy/h for EJ138/NAT. These were significantly lower than the external beam gamma radiation dose rate of 15 Gy/h. In the case of control lines which were incapable of [131I]MIBG uptake the mean absorbed doses following radiopharmaceutical were 0.03 – 0.23 Gy for UVW and 0.03 – 0.32 Gy for EJ138. Conclusion: [131I]MIBG treatment for ICCM production elicited a bystander dose-response profile similar to that generated by external beam gamma irradiation but with significantly greater cell death. PMID:24659931

  14. Organ doses from environmental exposures calculated using voxel phantoms of adults and children

    NASA Astrophysics Data System (ADS)

    Petoussi-Henss, Nina; Schlattl, H.; Zankl, M.; Endo, A.; Saito, K.

    2012-09-01

    This paper presents effective and organ dose conversion coefficients for members of the public due to environmental external exposures, calculated using the ICRP adult male and female reference computational phantoms as well as voxel phantoms of a baby, two children and four adult individual phantoms--one male and three female, one of them pregnant. Dose conversion coefficients are given for source geometries representing environmental radiation exposures, i.e. whole body irradiations from a volume source in air, representing a radioactive cloud, a plane source in the ground at a depth of 0.5 g cm-2, representing ground contamination by radioactive fall-out, and uniformly distributed natural sources in the ground. The organ dose conversion coefficients were calculated employing the Monte Carlo code EGSnrc simulating the photon transport in the voxel phantoms, and are given as effective and equivalent doses normalized to air kerma free-in-air at height 1 m above the ground in Sv Gy-1. The findings showed that, in general, the smaller the body mass of the phantom, the higher the dose. The difference in effective dose between an adult and an infant is 80-90% at 50 keV and less than 40% above 100 keV. Furthermore, dose equivalent rates for photon exposures of several radionuclides for the above environmental exposures were calculated with the most recent nuclear decay data. Data are shown for effective dose, thyroid, colon and red bone marrow. The results are expected to facilitate regulation of exposure to radiation, relating activities of radionuclides distributed in air and ground to dose of the public due to external radiation as well as the investigation of the radiological effects of major radiation accidents such as the recent one in Fukushima and the decision making of several committees.

  15. Monte Carlo photon beam modeling and commissioning for radiotherapy dose calculation algorithm.

    PubMed

    Toutaoui, A; Ait chikh, S; Khelassi-Toutaoui, N; Hattali, B

    2014-11-01

    The aim of the present work was a Monte Carlo verification of the Multi-grid superposition (MGS) dose calculation algorithm implemented in the CMS XiO (Elekta) treatment planning system and used to calculate the dose distribution produced by photon beams generated by the linear accelerator (linac) Siemens Primus. The BEAMnrc/DOSXYZnrc (EGSnrc package) Monte Carlo model of the linac head was used as a benchmark. In the first part of the work, the BEAMnrc was used for the commissioning of a 6 MV photon beam and to optimize the linac description to fit the experimental data. In the second part, the MGS dose distributions were compared with DOSXYZnrc using relative dose error comparison and γ-index analysis (2%/2 mm, 3%/3 mm), in different dosimetric test cases. Results show good agreement between simulated and calculated dose in homogeneous media for square and rectangular symmetric fields. The γ-index analysis confirmed that for most cases the MGS model and EGSnrc doses are within 3% or 3 mm. PMID:24947967

  16. Monte Carlo calculation of dose distributions in oligometastatic patients planned for spine stereotactic ablative radiotherapy

    NASA Astrophysics Data System (ADS)

    Moiseenko, V.; Liu, M.; Loewen, S.; Kosztyla, R.; Vollans, E.; Lucido, J.; Fong, M.; Vellani, R.; Popescu, I. A.

    2013-10-01

    Dosimetric consequences of plans optimized using the analytical anisotropic algorithm (AAA) implemented in the Varian Eclipse treatment planning system for spine stereotactic body radiotherapy were evaluated by re-calculating with BEAMnrc/DOSXYZnrc Monte Carlo. Six patients with spinal vertebral metastases were planned using volumetric modulated arc therapy. The planning goal was to cover at least 80% of the planning target volume with a prescribed dose of 35 Gy in five fractions. Tissue heterogeneity-corrected AAA dose distributions for the planning target volume and spinal canal planning organ-at-risk volume were compared against those obtained from Monte Carlo. The results showed that the AAA overestimated planning target volume coverage with the prescribed dose by up to 13.5% (mean 8.3% +/- 3.2%) when compared to Monte Carlo simulations. Maximum dose to spinal canal planning organ-at-risk volume calculated with Monte Carlo was consistently smaller than calculated with the treatment planning system and remained under spinal cord dose tolerance. Differences in dose distribution appear to be related to the dosimetric effects of accounting for body composition in Monte Carlo simulations. In contrast, the treatment planning system assumes that all tissues are water-equivalent in their composition and only differ in their electron density.

  17. The EXPURT model for calculating external gamma doses from deposited material in inhabited areas.

    PubMed

    Jones, J A; Singer, L N; Brown, J

    2006-01-01

    EXPURT, NRPB's model for calculating external gamma doses in inhabited areas, was originally developed in the mid-1980s. Deposition on surfaces in the area, the subsequent transfer of material between different surfaces or its removal from the system, and dose rates in various locations from material on the different surfaces are modelled. The model has been updated to take account of more recent experimental data on the transfer rates between surfaces and to make it more flexible for use in assessing dose rates following an accidental release. EXPURT is a compartmental model and models the transfer of material between the surfaces using a set of first order differential equations. It enables the impact of the decontamination of surfaces on doses and dose rates to be explored. The paper describes the EXPURT model and presents some preliminary results obtained using it. PMID:16242820

  18. Pretreatment verification of dose calculation and delivery by means of measurements with PLEXITOM™ phantom

    PubMed Central

    Wołowiec, Paweł; Kukołowicz, Paweł; Lis, Krzysztof

    2013-01-01

    Aim To validate a pretreatment verification method of dose calculation and dose delivery based on measurements with Metaplex PTW phantom. Background The dose-response relationships for local tumor control and radiosensitive tissue complications are strong. It is widely accepted that an accuracy of dose delivery of about 3.5% (one standard deviation) is required in modern radiotherapy. This goal is difficult to achieve. This paper describes our experience with the control of dose delivery and calculations at the ICRU reference point. Materials and methods The calculations of dose at the ICRU reference point performed with the treatment planning system CMS XiO were checked by measurements carried out in the PLEXITOM™ phantom. All measurements were performed with the ion chamber positioned in the phantom, at the central axis of the beam, at depth equivalent to the radiological depth (at gantry zero position). The source-to-phantom surface distance was always set to keep the source-to-detector distance equal to the reference point depth defined in the ICRU Report 50 (generally, 100 cm). The dose was measured according to IAEA TRS 398 report for measurements in solid phantoms. The measurement results were corrected with the actual accelerator's output factor and for the non-full scatter conditions. Measurements were made for 111 patients and 327 fields. Results The average differences between measurements and calculations were 0.03% (SD = 1.4%), 0.3% (SD = 1.0%), 0.1% (SD = 1.1%), 0.6% (SD = 1.8%), 0.3% (SD = 1.5%) for all measurements, for total dose, for pelvis, thorax and H&N patients, respectively. Only in 15 cases (4.6%), the difference between the measured and the calculated dose was greater than 3%. For these fields, a detailed analysis was undertaken. Conclusion The verification method provides an instantaneous verification of dose calculations before the beginning of a patient's treatment. It allows to detect differences smaller than 3.5%. PMID

  19. Site-specific range uncertainties caused by dose calculation algorithms for proton therapy.

    PubMed

    Schuemann, J; Dowdell, S; Grassberger, C; Min, C H; Paganetti, H

    2014-08-01

    The purpose of this study was to assess the possibility of introducing site-specific range margins to replace current generic margins in proton therapy. Further, the goal was to study the potential of reducing margins with current analytical dose calculations methods. For this purpose we investigate the impact of complex patient geometries on the capability of analytical dose calculation algorithms to accurately predict the range of proton fields. Dose distributions predicted by an analytical pencil-beam algorithm were compared with those obtained using Monte Carlo (MC) simulations (TOPAS). A total of 508 passively scattered treatment fields were analyzed for seven disease sites (liver, prostate, breast, medulloblastoma-spine, medulloblastoma-whole brain, lung and head and neck). Voxel-by-voxel comparisons were performed on two-dimensional distal dose surfaces calculated by pencil-beam and MC algorithms to obtain the average range differences and root mean square deviation for each field for the distal position of the 90% dose level (R90) and the 50% dose level (R50). The average dose degradation of the distal falloff region, defined as the distance between the distal position of the 80% and 20% dose levels (R80-R20), was also analyzed. All ranges were calculated in water-equivalent distances. Considering total range uncertainties and uncertainties from dose calculation alone, we were able to deduce site-specific estimations. For liver, prostate and whole brain fields our results demonstrate that a reduction of currently used uncertainty margins is feasible even without introducing MC dose calculations. We recommend range margins of 2.8% + 1.2 mm for liver and prostate treatments and 3.1% + 1.2 mm for whole brain treatments, respectively. On the other hand, current margins seem to be insufficient for some breast, lung and head and neck patients, at least if used generically. If no case specific adjustments are applied, a generic margin of 6.3% + 1.2

  20. Clinical implementation of full Monte Carlo dose calculation in proton beam therapy.

    PubMed

    Paganetti, Harald; Jiang, Hongyu; Parodi, Katia; Slopsema, Roelf; Engelsman, Martijn

    2008-09-01

    The goal of this work was to facilitate the clinical use of Monte Carlo proton dose calculation to support routine treatment planning and delivery. The Monte Carlo code Geant4 was used to simulate the treatment head setup, including a time-dependent simulation of modulator wheels (for broad beam modulation) and magnetic field settings (for beam scanning). Any patient-field-specific setup can be modeled according to the treatment control system of the facility. The code was benchmarked against phantom measurements. Using a simulation of the ionization chamber reading in the treatment head allows the Monte Carlo dose to be specified in absolute units (Gy per ionization chamber reading). Next, the capability of reading CT data information was implemented into the Monte Carlo code to model patient anatomy. To allow time-efficient dose calculation, the standard Geant4 tracking algorithm was modified. Finally, a software link of the Monte Carlo dose engine to the patient database and the commercial planning system was established to allow data exchange, thus completing the implementation of the proton Monte Carlo dose calculation engine ('DoC++'). Monte Carlo re-calculated plans are a valuable tool to revisit decisions in the planning process. Identification of clinically significant differences between Monte Carlo and pencil-beam-based dose calculations may also drive improvements of current pencil-beam methods. As an example, four patients (29 fields in total) with tumors in the head and neck regions were analyzed. Differences between the pencil-beam algorithm and Monte Carlo were identified in particular near the end of range, both due to dose degradation and overall differences in range prediction due to bony anatomy in the beam path. Further, the Monte Carlo reports dose-to-tissue as compared to dose-to-water by the planning system. Our implementation is tailored to a specific Monte Carlo code and the treatment planning system XiO (Computerized Medical Systems Inc

  1. Site-specific range uncertainties caused by dose calculation algorithms for proton therapy

    NASA Astrophysics Data System (ADS)

    Schuemann, J.; Dowdell, S.; Grassberger, C.; Min, C. H.; Paganetti, H.

    2014-08-01

    The purpose of this study was to assess the possibility of introducing site-specific range margins to replace current generic margins in proton therapy. Further, the goal was to study the potential of reducing margins with current analytical dose calculations methods. For this purpose we investigate the impact of complex patient geometries on the capability of analytical dose calculation algorithms to accurately predict the range of proton fields. Dose distributions predicted by an analytical pencil-beam algorithm were compared with those obtained using Monte Carlo (MC) simulations (TOPAS). A total of 508 passively scattered treatment fields were analyzed for seven disease sites (liver, prostate, breast, medulloblastoma-spine, medulloblastoma-whole brain, lung and head and neck). Voxel-by-voxel comparisons were performed on two-dimensional distal dose surfaces calculated by pencil-beam and MC algorithms to obtain the average range differences and root mean square deviation for each field for the distal position of the 90% dose level (R90) and the 50% dose level (R50). The average dose degradation of the distal falloff region, defined as the distance between the distal position of the 80% and 20% dose levels (R80-R20), was also analyzed. All ranges were calculated in water-equivalent distances. Considering total range uncertainties and uncertainties from dose calculation alone, we were able to deduce site-specific estimations. For liver, prostate and whole brain fields our results demonstrate that a reduction of currently used uncertainty margins is feasible even without introducing MC dose calculations. We recommend range margins of 2.8% + 1.2 mm for liver and prostate treatments and 3.1% + 1.2 mm for whole brain treatments, respectively. On the other hand, current margins seem to be insufficient for some breast, lung and head and neck patients, at least if used generically. If no case specific adjustments are applied, a generic margin of 6.3% + 1.2 mm would be

  2. SU-E-J-60: Efficient Monte Carlo Dose Calculation On CPU-GPU Heterogeneous Systems

    SciTech Connect

    Xiao, K; Chen, D. Z; Hu, X. S; Zhou, B

    2014-06-01

    Purpose: It is well-known that the performance of GPU-based Monte Carlo dose calculation implementations is bounded by memory bandwidth. One major cause of this bottleneck is the random memory writing patterns in dose deposition, which leads to several memory efficiency issues on GPU such as un-coalesced writing and atomic operations. We propose a new method to alleviate such issues on CPU-GPU heterogeneous systems, which achieves overall performance improvement for Monte Carlo dose calculation. Methods: Dose deposition is to accumulate dose into the voxels of a dose volume along the trajectories of radiation rays. Our idea is to partition this procedure into the following three steps, which are fine-tuned for CPU or GPU: (1) each GPU thread writes dose results with location information to a buffer on GPU memory, which achieves fully-coalesced and atomic-free memory transactions; (2) the dose results in the buffer are transferred to CPU memory; (3) the dose volume is constructed from the dose buffer on CPU. We organize the processing of all radiation rays into streams. Since the steps within a stream use different hardware resources (i.e., GPU, DMA, CPU), we can overlap the execution of these steps for different streams by pipelining. Results: We evaluated our method using a Monte Carlo Convolution Superposition (MCCS) program and tested our implementation for various clinical cases on a heterogeneous system containing an Intel i7 quad-core CPU and an NVIDIA TITAN GPU. Comparing with a straightforward MCCS implementation on the same system (using both CPU and GPU for radiation ray tracing), our method gained 2-5X speedup without losing dose calculation accuracy. Conclusion: The results show that our new method improves the effective memory bandwidth and overall performance for MCCS on the CPU-GPU systems. Our proposed method can also be applied to accelerate other Monte Carlo dose calculation approaches. This research was supported in part by NSF under Grants CCF

  3. Monte Carlo Calculations of Selected Dose Components in a Head Model for Boron Neutron Capture Therapy

    NASA Astrophysics Data System (ADS)

    Tymińska, Katarzyna

    2007-01-01

    Boron Neutron Capture Therapy is a very promising form of cancer therapy, consisting in irradiating a stable isotope of boron (10B) concentrated in tumor cells with a low energy neutron beam. This technique makes it possible to destroy tumor cells, leaving healthy tissues practically unaffected. In order to carry out the therapy in the proper way, the proper range of the neutron beam energy has to be chosen. In this paper we present the results of the calculations, using the MCNP code, aiming at studying the energetic dependence of the absorbed dose from the neutron capture reaction on boron (the therapeutic dose), and hydrogen and nitrogen (the injuring dose).

  4. Monte-Carlo Simulation of Radiation Track Structure and Calculation of Dose Deposition in Nanovolumes

    NASA Technical Reports Server (NTRS)

    Plante, I.; Cucinotta, F. A.

    2010-01-01

    INTRODUCTION: The radiation track structure is of crucial importance to understand radiation damage to molecules and subsequent biological effects. Of a particular importance in radiobiology is the induction of double-strand breaks (DSBs) by ionizing radiation, which are caused by clusters of lesions in DNA, and oxidative damage to cellular constituents leading to aberrant signaling cascades. DSB can be visualized within cell nuclei with gamma-H2AX experiments. MATERIAL AND METHODS: In DSB induction models, the DSB probability is usually calculated by the local dose obtained from a radial dose profile of HZE tracks. In this work, the local dose imparted by HZE ions is calculated directly from the 3D Monte-Carlo simulation code RITRACKS. A cubic volume of 5 micron edge (Figure 1) is irradiated by a (Fe26+)-56 ion of 1 GeV/amu (LET approx.150 keV/micron) and by a fluence of 450 H+ ions, 300 MeV/amu (LET approx. 0.3 keV/micron). In both cases, the dose deposited in the volume is approx.1 Gy. The dose is then calculated into each 3D pixels (voxels) of 20 nm edge and visualized in 3D. RESULTS AND DISCUSSION: The dose is deposited uniformly in the volume by the H+ ions. The voxels which receive a high dose (orange) corresponds to electron track ends. The dose is deposited differently by the 56Fe26+ ion. Very high dose (red) is deposited in voxels with direct ion traversal. Voxels with electron track ends (orange) are also found distributed around the path of the track. In both cases, the appearance of the dose distribution looks very similar to DSBs seen in gammaH2AX experiments, particularly when the visualization threshold is applied. CONCLUSION: The refinement of the dose calculation to the nanometer scale has revealed important differences in the energy deposition between high- and low-LET ions. Voxels of very high dose are only found in the path of high-LET ions. Interestingly, experiments have shown that DSB induced by high-LET radiation are more difficult to

  5. Dose Calculation For Accidental Release Of Radioactive Cloud Passing Over Jeddah

    NASA Astrophysics Data System (ADS)

    Alharbi, N. D.; Mayhoub, A. B.

    2011-12-01

    For the evaluation of doses after the reactor accident, in particular for the inhalation dose, a thorough knowledge of the concentration of the various radionuclide in air during the passage of the plume is required. In this paper we present an application of the Gaussian Plume Model (GPM) to calculate the atmospheric dispersion and airborne radionuclide concentration resulting from radioactive cloud over the city of Jeddah (KSA). The radioactive cloud is assumed to be emitted from a reactor of 10 MW power in postulated accidental release. Committed effective doses (CEDs) to the public at different distance from the source to the receptor are calculated. The calculations were based on meteorological condition and data of the Jeddah site. These data are: pasquill atmospheric stability is the class B and the wind speed is 2.4m/s at 10m height in the N direction. The residence time of some radionuclides considered in this study were calculated. The results indicate that, the values of doses first increase with distance, reach a maximum value and then gradually decrease. The total dose received by human is estimated by using the estimated values of residence time of each radioactive pollutant at different distances.

  6. Dose Calculation For Accidental Release Of Radioactive Cloud Passing Over Jeddah

    SciTech Connect

    Alharbi, N. D.; Mayhoub, A. B.

    2011-12-26

    For the evaluation of doses after the reactor accident, in particular for the inhalation dose, a thorough knowledge of the concentration of the various radionuclide in air during the passage of the plume is required. In this paper we present an application of the Gaussian Plume Model (GPM) to calculate the atmospheric dispersion and airborne radionuclide concentration resulting from radioactive cloud over the city of Jeddah (KSA). The radioactive cloud is assumed to be emitted from a reactor of 10 MW power in postulated accidental release. Committed effective doses (CEDs) to the public at different distance from the source to the receptor are calculated. The calculations were based on meteorological condition and data of the Jeddah site. These data are: pasquill atmospheric stability is the class B and the wind speed is 2.4m/s at 10m height in the N direction. The residence time of some radionuclides considered in this study were calculated. The results indicate that, the values of doses first increase with distance, reach a maximum value and then gradually decrease. The total dose received by human is estimated by using the estimated values of residence time of each radioactive pollutant at different distances.

  7. Parameterization of brachytherapy source phase space file for Monte Carlo-based clinical brachytherapy dose calculation

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Zou, W.; Chen, T.; Kim, L.; Khan, A.; Haffty, B.; Yue, N. J.

    2014-01-01

    A common approach to implementing the Monte Carlo method for the calculation of brachytherapy radiation dose deposition is to use a phase space file containing information on particles emitted from a brachytherapy source. However, the loading of the phase space file during the dose calculation consumes a large amount of computer random access memory, imposing a higher requirement for computer hardware. In this study, we propose a method to parameterize the information (e.g., particle location, direction and energy) stored in the phase space file by using several probability distributions. This method was implemented for dose calculations of a commercial Ir-192 high dose rate source. Dose calculation accuracy of the parameterized source was compared to the results observed using the full phase space file in a simple water phantom and in a clinical breast cancer case. The results showed the parameterized source at a size of 200 kB was as accurate as the phase space file represented source of 1.1 GB. By using the parameterized source representation, a compact Monte Carlo job can be designed, which allows an easy setup for parallel computing in brachytherapy planning.

  8. Calculated and measured depth dose profiles in a phantom exposed to neutron radiation fields

    SciTech Connect

    Scherpelz, R.I.; Tanner, J.E.; Sigalla, L.A.; Hadlock, D.E.

    1989-05-01

    An accurate evaluation of doses caused by external sources of neutron radiation depends on knowledge of the transport of radiation inside the human body. Health physicists use two primary methods for studying this radiation transport: computer calculations and measurements. Both computer calculations and measurements were performed under well controlled, nearly identical conditions to determine the extent of their agreement. A comparison of the dose profiles predicted by both measurements and calculations was thus possible. The measurements were performed in a cylindrical phantom made of tissue equivalent plastic. The phantom size, 61 cm high and 30 cm in diameter, was chosen to approximate the human torso and to match the dimensions of cylindrical phantoms used by previous calculations. Holes were drilled down through the phantom to accommodate small tissue equivalent proportional counters (TEPCs) at various depths in the phantom. These counters were used to measure the neutron dose inside the phantom when it was exposed to various sources of neutrons. The holes in the phantom could also accommodate miniature Geiger-Mueller detectors to measure the gamma component of the dose. Neutron and gamma dose profiles were measured for two different sources of neutrons: an unmoderated /sup 252/Cf source and a 733-keV neutron beam generated by a Van de Graaff accelerator. 14 refs., 13 figs., 11 tabs.

  9. Intensity-Modulated Radiotherapy for Locally Advanced Non-Small-Cell Lung Cancer: A Dose-Escalation Planning Study

    SciTech Connect

    Lievens, Yolande; Nulens, An; Gaber, Mousa Amr; Defraene, Gilles; De Wever, Walter; Stroobants, Sigrid; Van den Heuvel, Frank

    2011-05-01

    Purpose: To evaluate the potential for dose escalation with intensity-modulated radiotherapy (IMRT) in positron emission tomography-based radiotherapy planning for locally advanced non-small-cell lung cancer (LA-NSCLC). Methods and Materials: For 35 LA-NSCLC patients, three-dimensional conformal radiotherapy and IMRT plans were made to a prescription dose (PD) of 66 Gy in 2-Gy fractions. Dose escalation was performed toward the maximal PD using secondary endpoint constraints for the lung, spinal cord, and heart, with de-escalation according to defined esophageal tolerance. Dose calculation was performed using the Eclipse pencil beam algorithm, and all plans were recalculated using a collapsed cone algorithm. The normal tissue complication probabilities were calculated for the lung (Grade 2 pneumonitis) and esophagus (acute toxicity, grade 2 or greater, and late toxicity). Results: IMRT resulted in statistically significant decreases in the mean lung (p <.0001) and maximal spinal cord (p = .002 and 0005) doses, allowing an average increase in the PD of 8.6-14.2 Gy (p {<=}.0001). This advantage was lost after de-escalation within the defined esophageal dose limits. The lung normal tissue complication probabilities were significantly lower for IMRT (p <.0001), even after dose escalation. For esophageal toxicity, IMRT significantly decreased the acute NTCP values at the low dose levels (p = .0009 and p <.0001). After maximal dose escalation, late esophageal tolerance became critical (p <.0001), especially when using IMRT, owing to the parallel increases in the esophageal dose and PD. Conclusion: In LA-NSCLC, IMRT offers the potential to significantly escalate the PD, dependent on the lung and spinal cord tolerance. However, parallel increases in the esophageal dose abolished the advantage, even when using collapsed cone algorithms. This is important to consider in the context of concomitant chemoradiotherapy schedules using IMRT.

  10. Validation of fast Monte Carlo dose calculation in small animal radiotherapy with EBT3 radiochromic films.

    PubMed

    Noblet, C; Chiavassa, S; Smekens, F; Sarrut, D; Passal, V; Suhard, J; Lisbona, A; Paris, F; Delpon, G

    2016-05-01

    In preclinical studies, the absorbed dose calculation accuracy in small animals is fundamental to reliably investigate and understand observed biological effects. This work investigated the use of the split exponential track length estimator (seTLE), a new kerma based Monte Carlo dose calculation method for preclinical radiotherapy using a small animal precision micro irradiator, the X-RAD 225Cx. Monte Carlo modelling of the irradiator with GATE/GEANT4 was extensively evaluated by comparing measurements and simulations for half-value layer, percent depth dose, off-axis profiles and output factors in water and water-equivalent material for seven circular fields, from 20 mm down to 1 mm in diameter. Simulated and measured dose distributions in cylinders of water obtained for a 360° arc were also compared using dose, distance-to-agreement and gamma-index maps. Simulations and measurements agreed within 3% for all static beam configurations, with uncertainties estimated to 1% for the simulation and 3% for the measurements. Distance-to-agreement accuracy was better to 0.14 mm. For the arc irradiations, gamma-index maps of 2D dose distributions showed that the success rate was higher than 98%, except for the 0.1 cm collimator (92%). Using the seTLE method, MC simulations compute 3D dose distributions within minutes for realistic beam configurations with a clinically acceptable accuracy for beam diameter as small as 1 mm. PMID:27055114

  11. Calculation of Radiation Dose to Man from Radionuclides in the Environment.

    1981-02-17

    ARRRG permits rapid and consistent estimates of the radiation dose and dose commitment to man resulting from radioactive materials released to the environment. It is designed to calculate the dose and dose commitment following an accumulation of radionuclides in the environment from one year's ingestion of contaminated food products and from one year's external radiation exposure. ARRRG addresses aquatic exposure pathways. ARRRG can compute doses for five ingestion pathways such as fish, other aquatic animalsmore » or plants, or drinking water, as well as three external pathways: swimming, boating, or shoreline exposure. ARRRG calculates one-year doses and dose commitments from any one or combination of radionuclides for which sufficient biological data are available. As many as five of 23 possible organs and tissues, and mixtures of up to 100 radionuclides may be selected in any one case. The user may select up to 14 food categories with corresponding consumption rates, growing periods, and either irrigation rates or atmospheric deposition rates. These foods include various kinds of produce, grains, and animal products.« less

  12. Validation of fast Monte Carlo dose calculation in small animal radiotherapy with EBT3 radiochromic films

    NASA Astrophysics Data System (ADS)

    Noblet, C.; Chiavassa, S.; Smekens, F.; Sarrut, D.; Passal, V.; Suhard, J.; Lisbona, A.; Paris, F.; Delpon, G.

    2016-05-01

    In preclinical studies, the absorbed dose calculation accuracy in small animals is fundamental to reliably investigate and understand observed biological effects. This work investigated the use of the split exponential track length estimator (seTLE), a new kerma based Monte Carlo dose calculation method for preclinical radiotherapy using a small animal precision micro irradiator, the X-RAD 225Cx. Monte Carlo modelling of the irradiator with GATE/GEANT4 was extensively evaluated by comparing measurements and simulations for half-value layer, percent depth dose, off-axis profiles and output factors in water and water-equivalent material for seven circular fields, from 20 mm down to 1 mm in diameter. Simulated and measured dose distributions in cylinders of water obtained for a 360° arc were also compared using dose, distance-to-agreement and gamma-index maps. Simulations and measurements agreed within 3% for all static beam configurations, with uncertainties estimated to 1% for the simulation and 3% for the measurements. Distance-to-agreement accuracy was better to 0.14 mm. For the arc irradiations, gamma-index maps of 2D dose distributions showed that the success rate was higher than 98%, except for the 0.1 cm collimator (92%). Using the seTLE method, MC simulations compute 3D dose distributions within minutes for realistic beam configurations with a clinically acceptable accuracy for beam diameter as small as 1 mm.

  13. Development of a New Shielding Model for JB-Line Dose Rate Calculations

    SciTech Connect

    Buckner, M.R.

    2001-08-09

    This report describes the shielding model development for the JB-Line Upgrade project. The product of this effort is a simple-to-use but accurate method of estimating the personnel dose expected for various operating conditions on the line. The current techniques for shielding calculations use transport codes such as ANISN which, while accurate for geometries which can be accurately approximated as one dimensional slabs, cylinders or spheres, fall short in calculating configurations in which two-or three-dimensional effects (e.g., streaming) play a role in the dose received by workers.

  14. The difference of scoring dose to water or tissues in Monte Carlo dose calculations for low energy brachytherapy photon sources

    SciTech Connect

    Landry, Guillaume; Reniers, Brigitte; Pignol, Jean-Philippe; Beaulieu, Luc; Verhaegen, Frank

    2011-03-15

    Purpose: The goal of this work is to compare D{sub m,m} (radiation transported in medium; dose scored in medium) and D{sub w,m} (radiation transported in medium; dose scored in water) obtained from Monte Carlo (MC) simulations for a subset of human tissues of interest in low energy photon brachytherapy. Using low dose rate seeds and an electronic brachytherapy source (EBS), the authors quantify the large cavity theory conversion factors required. The authors also assess whether applying large cavity theory utilizing the sources' initial photon spectra and average photon energy induces errors related to spatial spectral variations. First, ideal spherical geometries were investigated, followed by clinical brachytherapy LDR seed implants for breast and prostate cancer patients. Methods: Two types of dose calculations are performed with the GEANT4 MC code. (1) For several human tissues, dose profiles are obtained in spherical geometries centered on four types of low energy brachytherapy sources: {sup 125}I, {sup 103}Pd, and {sup 131}Cs seeds, as well as an EBS operating at 50 kV. Ratios of D{sub w,m} over D{sub m,m} are evaluated in the 0-6 cm range. In addition to mean tissue composition, compositions corresponding to one standard deviation from the mean are also studied. (2) Four clinical breast (using {sup 103}Pd) and prostate (using {sup 125}I) brachytherapy seed implants are considered. MC dose calculations are performed based on postimplant CT scans using prostate and breast tissue compositions. PTV D{sub 90} values are compared for D{sub w,m} and D{sub m,m}. Results: (1) Differences (D{sub w,m}/D{sub m,m}-1) of -3% to 70% are observed for the investigated tissues. For a given tissue, D{sub w,m}/D{sub m,m} is similar for all sources within 4% and does not vary more than 2% with distance due to very moderate spectral shifts. Variations of tissue composition about the assumed mean composition influence the conversion factors up to 38%. (2) The ratio of D{sub 90(w

  15. Dosimetric impact of Acuros XB deterministic radiation transport algorithm for heterogeneous dose calculation in lung cancer

    SciTech Connect

    Han Tao; Followill, David; Repchak, Roman; Molineu, Andrea; Howell, Rebecca; Salehpour, Mohammad; Mikell, Justin; Mourtada, Firas

    2013-05-15

    Purpose: The novel deterministic radiation transport algorithm, Acuros XB (AXB), has shown great potential for accurate heterogeneous dose calculation. However, the clinical impact between AXB and other currently used algorithms still needs to be elucidated for translation between these algorithms. The purpose of this study was to investigate the impact of AXB for heterogeneous dose calculation in lung cancer for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Methods: The thorax phantom from the Radiological Physics Center (RPC) was used for this study. IMRT and VMAT plans were created for the phantom in the Eclipse 11.0 treatment planning system. Each plan was delivered to the phantom three times using a Varian Clinac iX linear accelerator to ensure reproducibility. Thermoluminescent dosimeters (TLDs) and Gafchromic EBT2 film were placed inside the phantom to measure delivered doses. The measurements were compared with dose calculations from AXB 11.0.21 and the anisotropic analytical algorithm (AAA) 11.0.21. Two dose reporting modes of AXB, dose-to-medium in medium (D{sub m,m}) and dose-to-water in medium (D{sub w,m}), were studied. Point doses, dose profiles, and gamma analysis were used to quantify the agreement between measurements and calculations from both AXB and AAA. The computation times for AAA and AXB were also evaluated. Results: For the RPC lung phantom, AAA and AXB dose predictions were found in good agreement to TLD and film measurements for both IMRT and VMAT plans. TLD dose predictions were within 0.4%-4.4% to AXB doses (both D{sub m,m} and D{sub w,m}); and within 2.5%-6.4% to AAA doses, respectively. For the film comparisons, the gamma indexes ({+-}3%/3 mm criteria) were 94%, 97%, and 98% for AAA, AXB{sub Dm,m}, and AXB{sub Dw,m}, respectively. The differences between AXB and AAA in dose-volume histogram mean doses were within 2% in the planning target volume, lung, heart, and within 5% in the spinal cord

  16. Analytic IMRT dose calculations utilizing Monte Carlo to predict MLC fluence modulation

    PubMed Central

    Mihaylov, I. B.; Lerma, F. A.; Wu, Y.; Siebers, J. V.

    2007-01-01

    A hybrid dose-computation method is designed which accurately accounts for multileaf collimator (MLC)-induced intensity modulation in intensity modulated radiation therapy (IMRT) dose calculations. The method employs Monte Carlo (MC) modeling to determine the fluence modulation caused by the delivery of dynamic or multisegmental (step-and-shoot) MLC fields, and a conventional dose-computation algorithm to estimate the delivered dose to a phantom or a patient. Thus, it determines the IMRT fluence prediction accuracy achievable by analytic methods in the limit that the analytic method includes all details of the MLC leaf transport and scatter. The hybrid method is validated and benchmarked by comparison with in-phantom film dose measurements, as well as dose calculations from two in-house, and two commercial treatment planning system analytic fluence estimation methods. All computation methods utilize the same dose algorithm to calculate dose to a phantom, varying only in the estimation of the MLC modulation of the incident photon energy fluence. Gamma analysis, with respect to measured two-dimensional (2D) dose planes, is used to benchmark each algorithm’s performance. The analyzed fields include static and dynamic test patterns, as well as fields from ten DMLC IMRT treatment plans (79 fields) and five SMLC treatment plans (29 fields). The test fields (fully closed MLC, picket fence, sliding windows of different size, and leaf-tip profiles) cover the extremes of MLC usage during IMRT, while the patient fields represent realistic clinical conditions. Of the methods tested, the hybrid method most accurately reproduces measurements. For the hybrid method, 79 of 79 DMLC field calculations have γ ≤1 (3% /3 mm) for more than 95% of the points (per field) while for SMLC fields, 27 of 29 pass the same criteria. The analytic energy fluence estimation methods show inferior pass rates, with 76 of 79 DMLC and 24 of 29 SMLC fields having more than 95% of the test points

  17. Calculation of Dose Deposition in 3D Voxels by Heavy Ions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2010-01-01

    The biological response to high-LET radiation is very different from low-LET radiation, and can be partly attributed to the energy deposition by the radiation. Several experiments, notably detection of gamma-H2AX foci by immunofluorescence, has revealed important differences in the nature and in the spatial distribution of double-strand breaks (DSB) induced by low- and high-LET radiations. Many calculations, most of which are based on amorphous track models with radial dose, have been combined with chromosome models to calculate the number and distribution of DSB within nuclei and chromosome aberrations. In this work, the Monte-Carlo track structure simulation code RITRACKS have been used to calculate directly the energy deposition in voxels (3D pixels). A cubic volume of 5 micrometers of side was irradiated by 1) 450 (1)H+ ions of 300 MeV (LET is approximately 0.3 keV/micrometer) and 2) by 1 (56)Fe26+ ion of 1 GeV/amu (LET is approximately 150 keV/micrometer). In both cases, the dose deposited in the volume is approximately 1 Gy. All energy deposition events are recorded and dose is calculated in voxels of 20 micrometers of side. The voxels are then visualized in 3D by using a color scale to represent the intensity of the dose in a voxel. This simple approach has revealed several important points which may help understand experimental observations. In both simulations, voxels which receive low dose are the most numerous, and those corresponding to electron track ends received a dose which is in the higher range. The dose voxels are distributed randomly and scattered uniformly within the volume irradiated by low-LET radiation. The distribution of the voxels shows major differences for the (56)Fe26+ ion. The track structure can still be seen, and voxels with much higher dose are found in the region corresponding to the track "core". These high-dose voxels are not found in the low-LET irradiation simulation and may be responsible for DSB that are more difficult to

  18. An algorithm to calculate a collapsed arc dose matrix in volumetric modulated arc therapy

    SciTech Connect

    Arumugam, Sankar; Xing Aitang; Jameson, Michael; Holloway, Lois

    2013-07-15

    Purpose: The delivery of volumetric modulated arc therapy (VMAT) is more complex than other conformal radiotherapy techniques. In this work, the authors present the feasibility of performing routine verification of VMAT delivery using a dose matrix measured by a gantry mounted 2D ion chamber array and corresponding dose matrix calculated by an inhouse developed algorithm.Methods: Pinnacle, v9.0, treatment planning system (TPS) was used in this study to generate VMAT plans for a 6 MV photon beam from an Elekta-Synergy linear accelerator. An algorithm was developed and implemented with inhouse computer code to calculate the dose matrix resulting from a VMAT arc in a plane perpendicular to the beam at isocenter. The algorithm was validated using measurement of standard patterns and clinical VMAT plans with a 2D ion chamber array. The clinical VMAT plans were also validated using ArcCHECK measurements. The measured and calculated dose matrices were compared using gamma ({gamma}) analysis with 3%/3 mm criteria and {gamma} tolerance of 1.Results: The dose matrix comparison of standard patterns has shown excellent agreement with the mean {gamma} pass rate 97.7 ({sigma}= 0.4)%. The validation of clinical VMAT plans using the dose matrix predicted by the algorithm and the corresponding measured dose matrices also showed good agreement with the mean {gamma} pass rate of 97.6 ({sigma}= 1.6)%. The validation of clinical VMAT plans using ArcCHECK measurements showed a mean pass rate of 95.6 ({sigma}= 1.8)%.Conclusions: The developed algorithm was shown to accurately predict the dose matrix, in a plane perpendicular to the beam, by considering all possible leaf trajectories in a VMAT delivery. This enables the verification of VMAT delivery using a 2D array detector mounted on a treatment head.

  19. Technological advances in hybrid imaging and impact on dose.

    PubMed

    Mattsson, Sören; Andersson, Martin; Söderberg, Marcus

    2015-07-01

    New imaging technologies utilising X-rays and radiopharmaceuticals have developed rapidly. Clinical application of computed tomography (CT) has revolutionised medical imaging and plays an enormous role in medical care. Due to technical improvements, spatial, contrast and temporal resolutions have continuously improved. In spite of significant reduction of CT doses during recent years, CT is still a dominating source of radiation exposure to the population. Combinations with single photon emission computed tomography (SPECT) and positron emission tomography (PET) and especially the use of SPECT/CT and PET/CT, provide important additional information about physiology as well as cellular and molecular events. However, significant dose contributions from SPECT and PET occur, making PET/CT and SPECT/CT truly high dose procedures. More research should be done to find optimal activities of radiopharmaceuticals for various patient groups and investigations. The implementation of simple protocol adjustments, including individually based administration, encouraged hydration, forced diuresis and use of optimised voiding intervals, laxatives, etc., can reduce the radiation exposure to the patients. New data about staff doses to fingers, hands and eye lenses indicate that finger doses could be a problem, but not doses to the eye lenses and to the whole body. PMID:25802466

  20. Fetal doses to pregnant patients from CT with tube current modulation calculated using Monte Carlo simulations and realistic phantoms

    PubMed Central

    Gu, Jianwei; Xu, X. George; Caracappa, Peter F.; Liu, Bob

    2013-01-01

    To investigate the radiation dose to the fetus using retrospective tube current modulation (TCM) data selected from archived clinical records. This paper describes the calculation of fetal doses using retrospective TCM data and Monte Carlo (MC) simulations. Three TCM schemes were adopted for use with three pregnant patient phantoms. MC simulations were used to model CT scanners, TCM schemes and pregnant patients. Comparisons between organ doses from TCM schemes and those from non-TCM schemes show that these three TCM schemes reduced fetal doses by 14, 18 and 25 %, respectively. These organ doses were also compared with those from ImPACT calculation. It is found that the difference between the calculated fetal dose and the ImPACT reported dose is as high as 46 %. This work demonstrates methods to study organ doses from various TCM protocols and potential ways to improve the accuracy of CT dose calculation for pregnant patients. PMID:23222824

  1. Dose measurements and calculations in the epithermal neutron beam at the Brookhaven Medical Research Reactor (BMRR)

    SciTech Connect

    Fairchild, R.G.; Greenberg, D.; Kamen, Y.; Fiarman, S. . Medical Dept.); Benary, V. . Medical Dept. Tel Aviv Univ. ); Kalef-Ezra, J. . Medical Dept. Ioannina Univ. ); Wielopolski, L. . Medical Dept. State Univ. of New

    1990-01-01

    The characteristics of the epithermal neutron beam at BMRR were measured, calculated, and reported. This beam has already been used for animal irradiations. We anticipate that it will be used for clinical trials. Thermal and epithermal neutron flux densities distributions, and dose rate distributions, as a function of depth were measured in a lucite dog-head phantom. Monte Carlo calculations were performed and compared with the measured values. 2 refs., 4 figs., 1 tab.

  2. A pre–postintervention study to evaluate the impact of dose calculators on the accuracy of gentamicin and vancomycin initial doses

    PubMed Central

    Hamad, Anas; Cavell, Gillian; Hinton, James; Wade, Paul; Whittlesea, Cate

    2015-01-01

    Objectives Gentamicin and vancomycin are narrow-therapeutic-index antibiotics with potential for high toxicity requiring dose individualisation and continuous monitoring. Clinical decision support (CDS) tools have been effective in reducing gentamicin and vancomycin dosing errors. Online dose calculators for these drugs were implemented in a London National Health Service hospital. This study aimed to evaluate the impact of these calculators on the accuracy of gentamicin and vancomycin initial doses. Methods The study used a pre–postintervention design. Data were collected using electronic patient records and paper notes. Random samples of gentamicin and vancomycin initial doses administered during the 8 months before implementation of the calculators were assessed retrospectively against hospital guidelines. Following implementation of the calculators, doses were assessed prospectively. Any gentamicin dose not within ±10% and any vancomycin dose not within ±20% of the guideline-recommended dose were considered incorrect. Results The intranet calculator pages were visited 721 times (gentamicin=333; vancomycin=388) during the 2-month period following the calculators’ implementation. Gentamicin dose errors fell from 61.5% (120/195) to 44.2% (95/215), p<0.001. Incorrect vancomycin loading doses fell from 58.1% (90/155) to 32.4% (46/142), p<0.001. Incorrect vancomycin first maintenance doses fell from 55.5% (86/155) to 33.1% (47/142), p<0.001. Loading and first maintenance vancomycin doses were both incorrect in 37.4% (58/155) of patients before and 13.4% (19/142) after calculator implementation, p<0.001. Conclusions This study suggests that gentamicin and vancomycin dose calculators significantly improved the prescribing of initial doses of these agents. Therefore, healthcare organisations should consider using such CDS tools to support the prescribing of these high-risk drugs. PMID:26044758

  3. X-ray dose estimation from cathode ray tube monitors by Monte Carlo calculation.

    PubMed

    Khaledi, Navid; Arbabi, Azim; Dabaghi, Moloud

    2015-04-01

    Cathode Ray Tube (CRT) monitors are associated with the possible emission of bremsstrahlung radiation produced by electrons striking the monitor screen. Because of the low dose rate, accurate dosimetry is difficult. In this study, the dose equivalent (DE) and effective dose (ED) to an operator working in front of the monitor have been calculated using the Monte Carlo (MC) method by employing the MCNP code. The mean energy of photons reaching the operator was above 17 keV. The phantom ED was 454 μSv y (348 nSv h), which was reduced to 16 μSv y (12 nSv h) after adding a conventional leaded glass sheet. The ambient dose equivalent (ADE) and personal dose equivalent (PDE) for the head, neck, and thorax of the phantom were also calculated. The uncertainty of calculated ED, ADE, and PDE ranged from 3.3% to 10.7% and 4.2% to 14.6% without and with the leaded glass, respectively. PMID:25706133

  4. Dose-calculation algorithms in the context of inhomogeneity corrections for high energy photon beams

    SciTech Connect

    Papanikolaou, Niko; Stathakis, Sotirios

    2009-10-15

    Radiation therapy has witnessed a plethora of innovations and developments in the past 15 years. Since the introduction of computed tomography for treatment planning there has been a steady introduction of new methods to refine treatment delivery. Imaging continues to be an integral part of the planning, but also the delivery, of modern radiotherapy. However, all the efforts of image guided radiotherapy, intensity-modulated planning and delivery, adaptive radiotherapy, and everything else that we pride ourselves in having in the armamentarium can fall short, unless there is an accurate dose-calculation algorithm. The agreement between the calculated and delivered doses is of great significance in radiation therapy since the accuracy of the absorbed dose as prescribed determines the clinical outcome. Dose-calculation algorithms have evolved greatly over the years in an effort to be more inclusive of the effects that govern the true radiation transport through the human body. In this Vision 20/20 paper, we look back to see how it all started and where things are now in terms of dose algorithms for photon beams and the inclusion of tissue heterogeneities. Convolution-superposition algorithms have dominated the treatment planning industry for the past few years. Monte Carlo techniques have an inherent accuracy that is superior to any other algorithm and as such will continue to be the gold standard, along with measurements, and maybe one day will be the algorithm of choice for all particle treatment planning in radiation therapy.

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

    SciTech Connect

    Smans, Kristien; Tapiovaara, Markku; Cannie, Mieke; Struelens, Lara; Vanhavere, Filip; Smet, Marleen; Bosmans, Hilde

    2008-02-15

    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 anatomical 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.

  6. Comparison of selected dose calculation algorithms in radiotherapy treatment planning for tissues with inhomogeneities

    NASA Astrophysics Data System (ADS)

    Woon, Y. L.; Heng, S. P.; Wong, J. H. D.; Ung, N. M.

    2016-03-01

    Inhomogeneity correction is recommended for accurate dose calculation in radiotherapy treatment planning since human body are highly inhomogeneous with the presence of bones and air cavities. However, each dose calculation algorithm has its own limitations. This study is to assess the accuracy of five algorithms that are currently implemented for treatment planning, including pencil beam convolution (PBC), superposition (SP), anisotropic analytical algorithm (AAA), Monte Carlo (MC) and Acuros XB (AXB). The calculated dose was compared with the measured dose using radiochromic film (Gafchromic EBT2) in inhomogeneous phantoms. In addition, the dosimetric impact of different algorithms on intensity modulated radiotherapy (IMRT) was studied for head and neck region. MC had the best agreement with the measured percentage depth dose (PDD) within the inhomogeneous region. This was followed by AXB, AAA, SP and PBC. For IMRT planning, MC algorithm is recommended for treatment planning in preference to PBC and SP. The MC and AXB algorithms were found to have better accuracy in terms of inhomogeneity correction and should be used for tumour volume within the proximity of inhomogeneous structures.

  7. An investigation of voxel geometries for MCNP-based radiation dose calculations.

    PubMed

    Zhang, Juying; Bednarz, Bryan; Xu, X George

    2006-11-01

    Voxelized geometry such as those obtained from medical images is increasingly used in Monte Carlo calculations of absorbed doses. One useful application of calculated absorbed dose is the determination of fluence-to-dose conversion factors for different organs. However, confusion still exists about how such a geometry is defined and how the energy deposition is best computed, especially involving a popular code, MCNP5. This study investigated two different types of geometries in the MCNP5 code, cell and lattice definitions. A 10 cm x 10 cm x 10 cm test phantom, which contained an embedded 2 cm x 2 cm x 2 cm target at its center, was considered. A planar source emitting parallel photons was also considered in the study. The results revealed that MCNP5 does not calculate total target volume for multi-voxel geometries. Therefore, tallies which involve total target volume must be divided by the user by the total number of voxels to obtain a correct dose result. Also, using planar source areas greater than the phantom size results in the same fluence-to-dose conversion factor. PMID:17023800

  8. An empirical model for calculation of the collimator contamination dose in therapeutic proton beams

    NASA Astrophysics Data System (ADS)

    Vidal, M.; De Marzi, L.; Szymanowski, H.; Guinement, L.; Nauraye, C.; Hierso, E.; Freud, N.; Ferrand, R.; François, P.; Sarrut, D.

    2016-02-01

    Collimators are used as lateral beam shaping devices in proton therapy with passive scattering beam lines. The dose contamination due to collimator scattering can be as high as 10% of the maximum dose and influences calculation of the output factor or monitor units (MU). To date, commercial treatment planning systems generally use a zero-thickness collimator approximation ignoring edge scattering in the aperture collimator and few analytical models have been proposed to take scattering effects into account, mainly limited to the inner collimator face component. The aim of this study was to characterize and model aperture contamination by means of a fast and accurate analytical model. The entrance face collimator scatter distribution was modeled as a 3D secondary dose source. Predicted dose contaminations were compared to measurements and Monte Carlo simulations. Measurements were performed on two different proton beam lines (a fixed horizontal beam line and a gantry beam line) with divergent apertures and for several field sizes and energies. Discrepancies between analytical algorithm dose prediction and measurements were decreased from 10% to 2% using the proposed model. Gamma-index (2%/1 mm) was respected for more than 90% of pixels. The proposed analytical algorithm increases the accuracy of analytical dose calculations with reasonable computation times.

  9. Accuracy of out-of-field dose calculations by a commercial treatment planning system

    PubMed Central

    Howell, Rebecca M; Scarboro, Sarah B; Kry, S F; Yaldo, Derek Z

    2011-01-01

    The dosimetric accuracy of treatment planning systems (TPSs) decreases for locations outside the treatment field borders. However, the true accuracy of specific TPSs for locations beyond the treatment field borders is not well documented. Our objective was to quantify the accuracy of out-of-field dose predicted by the commercially available Eclipse version 8.6 TPS (Varian Medical Systems, Palo Alto, CA) for a clinical treatment delivered on a Varian Clinac 2100. We calculated (in the TPS) and determined (with thermoluminescent dosimeters) doses at a total of 238 points of measurement (with distance from the field edge ranging from 3.75 to 11.25 cm). Our comparisons determined that the Eclipse TPS underestimated out-of-field doses by an average of 40% over the range of distances examined. As the distance from the treatment field increased, the TPS underestimated the dose with increasing magnitude—up to 55% at 11.25 cm from the treatment field border. These data confirm that accuracy beyond the treatment border is inadequate, and out-of-field data from TPSs should be used only with a clear understanding of this limitation. Studies that require accurate out-of-field dose should use other dose reconstruction methods, such as direct measurements or Monte Carlo calculations. PMID:21076191

  10. Site-specific range uncertainties caused by dose calculation algorithms for proton therapy

    PubMed Central

    Schuemann, J.; Dowdell, S.; Grassberger, C.; Min, C. H.; Paganetti, H.

    2014-01-01

    The purpose of this study was to investigate the impact of complex patient geometries on the capability of analytical dose calculation algorithms to accurately predict the range of proton fields. Dose distributions predicted by an analytical pencil-beam algorithm were compared with those obtained using Monte Carlo simulations (TOPAS). A total of 508 passively scattered treatment fields were analyzed for 7 disease sites (liver, prostate, breast, medulloblastoma-spine, medulloblastoma-whole brain, lung and head & neck). Voxel-by-voxel comparisons were performed on two-dimensional distal dose surfaces calculated by pencil-beam and Monte Carlo algorithms to obtain the average range differences (ARD) and root mean square deviation (RMSD) for each field for the distal position of the 90% dose level (R90) and the 50% dose level (R50). The average dose degradation (ADD) of the distal falloff region, defined as the distance between the distal position of the 80% and 20% dose levels (R80-R20), was also analyzed. All ranges were calculated in water-equivalent distances. Considering total range uncertainties and uncertainties from dose calculation alone, we were able to deduce site-specific estimations. For liver, prostate and whole brain fields our results demonstrate that a reduction of currently used uncertainty margins is feasible even without introducing Monte Carlo dose calculations. We recommend range margins of 2.8% + 1.2 mm for liver and prostate treatments and 3.1% + 1.2 mm for whole brain treatments, respectively. On the other hand, current margins seem to be insufficient for some breast, lung and head & neck patients, at least if used generically. If no case specific adjustments are applied, a generic margin of 6.3% + 1.2 mm would be needed for breast, lung and head & neck treatments. We conclude that currently used generic range uncertainty margins in proton therapy should be redefined site specific and that complex geometries may require a field specific

  11. Radiation therapy for stage IIA and IIB testicular seminoma: peripheral dose calculations and risk assessments

    NASA Astrophysics Data System (ADS)

    Mazonakis, Michalis; Berris, Theocharris; Lyraraki, Efrossyni; Damilakis, John

    2015-03-01

    This study was conducted to calculate the peripheral dose to critical structures and assess the radiation risks from modern radiotherapy for stage IIA/IIB testicular seminoma. A Monte Carlo code was used for treatment simulation on a computational phantom representing an average adult. The initial treatment phase involved anteroposterior and posteroanaterior modified dog-leg fields exposing para-aortic and ipsilateral iliac lymph nodes followed by a cone-down phase for nodal mass irradiation. Peripheral doses were calculated using different modified dog-leg field dimensions and an extended conventional dog-leg portal. The risk models of the BEIR-VII report and ICRP-103 were combined with dosimetric calculations to estimate the probability of developing stochastic effects. Radiotherapy for stage IIA seminoma with a target dose of 30 Gy resulted in a range of 23.0-603.7 mGy to non-targeted peripheral tissues and organs. The corresponding range for treatment of stage IIB disease to a cumulative dose of 36 Gy was 24.2-633.9 mGy. A dose variation of less than 13% was found by altering the field dimensions. Radiotherapy with the conventional instead of the modern modified dog-leg field increased the peripheral dose up to 8.2 times. The calculated heart doses of 589.0-632.9 mGy may increase the risk for developing cardiovascular diseases whereas the testicular dose of more than 231.9 mGy may lead to a temporary infertility. The probability of birth abnormalities in the offspring of cancer survivors was below 0.13% which is much lower than the spontaneous mutation rate. Abdominoplevic irradiation may increase the lifetime intrinsic risk for the induction of secondary malignancies by 0.6-3.9% depending upon the site of interest, patient’s age and tumor dose. Radiotherapy for stage IIA/IIB seminoma with restricted fields and low doses is associated with an increased morbidity. These data may allow the definition of a risk-adapted follow-up scheme for long

  12. Head-and-neck IMRT treatments assessed with a Monte Carlo dose calculation engine

    NASA Astrophysics Data System (ADS)

    Seco, J.; Adams, E.; Bidmead, M.; Partridge, M.; Verhaegen, F.

    2005-03-01

    IMRT is frequently used in the head-and-neck region, which contains materials of widely differing densities (soft tissue, bone, air-cavities). Conventional methods of dose computation for these complex, inhomogeneous IMRT cases involve significant approximations. In the present work, a methodology for the development, commissioning and implementation of a Monte Carlo (MC) dose calculation engine for intensity modulated radiotherapy (MC-IMRT) is proposed which can be used by radiotherapy centres interested in developing MC-IMRT capabilities for research or clinical evaluations. The method proposes three levels for developing, commissioning and maintaining a MC-IMRT dose calculation engine: (a) development of a MC model of the linear accelerator, (b) validation of MC model for IMRT and (c) periodic quality assurance (QA) of the MC-IMRT system. The first step, level (a), in developing an MC-IMRT system is to build a model of the linac that correctly predicts standard open field measurements for percentage depth-dose and off-axis ratios. Validation of MC-IMRT, level (b), can be performed in a rando phantom and in a homogeneous water equivalent phantom. Ultimately, periodic quality assurance of the MC-IMRT system is needed to verify the MC-IMRT dose calculation system, level (c). Once the MC-IMRT dose calculation system is commissioned it can be applied to more complex clinical IMRT treatments. The MC-IMRT system implemented at the Royal Marsden Hospital was used for IMRT calculations for a patient undergoing treatment for primary disease with nodal involvement in the head-and-neck region (primary treated to 65 Gy and nodes to 54 Gy), while sparing the spinal cord, brain stem and parotid glands. Preliminary MC results predict a decrease of approximately 1-2 Gy in the median dose of both the primary tumour and nodal volumes (compared with both pencil beam and collapsed cone). This is possibly due to the large air-cavity (the larynx of the patient) situated in the centre

  13. GPU-based ultra-fast dose calculation using a finite size pencil beam model

    NASA Astrophysics Data System (ADS)

    Gu, Xuejun; Choi, Dongju; Men, Chunhua; Pan, Hubert; Majumdar, Amitava; Jiang, Steve B.

    2009-10-01

    Online adaptive radiation therapy (ART) is an attractive concept that promises the ability to deliver an optimal treatment in response to the inter-fraction variability in patient anatomy. However, it has yet to be realized due to technical limitations. Fast dose deposit coefficient calculation is a critical component of the online planning process that is required for plan optimization of intensity-modulated radiation therapy (IMRT). Computer graphics processing units (GPUs) are well suited to provide the requisite fast performance for the data-parallel nature of dose calculation. In this work, we develop a dose calculation engine based on a finite-size pencil beam (FSPB) algorithm and a GPU parallel computing framework. The developed framework can accommodate any FSPB model. We test our implementation in the case of a water phantom and the case of a prostate cancer patient with varying beamlet and voxel sizes. All testing scenarios achieved speedup ranging from 200 to 400 times when using a NVIDIA Tesla C1060 card in comparison with a 2.27 GHz Intel Xeon CPU. The computational time for calculating dose deposition coefficients for a nine-field prostate IMRT plan with this new framework is less than 1 s. This indicates that the GPU-based FSPB algorithm is well suited for online re-planning for adaptive radiotherapy.

  14. Personal radiation doses in PET/CT facility: measurements vs. calculations.

    PubMed

    Hippeläinen, E; Nikkinen, P; Ihalainen, T; Uusi-Simola, J; Savolainen, S

    2008-01-01

    The estimation of shielding requirement of a new positron emission tomography (PET) facility is essential. Because of penetrating annihilation photons, not only radiation safety in the vicinity of patients should be considered, but also rooms adjacent to uptake and imaging rooms should be taken into account. Before installing a PET/CT camera to nuclear medicine facilities of Helsinki University Central Hospital (HUCH), a typical PET imaging day was simulated using phantoms. Phantoms were filled with 300 +/- 36 MBq of (18)F isotope and dose rates were measured at 12 central locations in the laboratory. In addition to measurements, dose rates were also calculated using guidelines of AAPM Task Group 108. The relationship between the measured and calculated dose rates was found to be good and statistically significant, using Pearson's correlation test. The evaluated monthly doses were compared with personal dosemeter readings. AAPM's report gives practical tools for evaluation of radiation shielding. Calculations can be carried out successfully for existing hospital complexes too. However, calculations should be carried out carefully, because especially doors, windows and partitions can easily cause underestimation of shielding requirements as shown in this work. PMID:18713782

  15. GPU-based ultra-fast dose calculation using a finite size pencil beam model.

    PubMed

    Gu, Xuejun; Choi, Dongju; Men, Chunhua; Pan, Hubert; Majumdar, Amitava; Jiang, Steve B

    2009-10-21

    Online adaptive radiation therapy (ART) is an attractive concept that promises the ability to deliver an optimal treatment in response to the inter-fraction variability in patient anatomy. However, it has yet to be realized due to technical limitations. Fast dose deposit coefficient calculation is a critical component of the online planning process that is required for plan optimization of intensity-modulated radiation therapy (IMRT). Computer graphics processing units (GPUs) are well suited to provide the requisite fast performance for the data-parallel nature of dose calculation. In this work, we develop a dose calculation engine based on a finite-size pencil beam (FSPB) algorithm and a GPU parallel computing framework. The developed framework can accommodate any FSPB model. We test our implementation in the case of a water phantom and the case of a prostate cancer patient with varying beamlet and voxel sizes. All testing scenarios achieved speedup ranging from 200 to 400 times when using a NVIDIA Tesla C1060 card in comparison with a 2.27 GHz Intel Xeon CPU. The computational time for calculating dose deposition coefficients for a nine-field prostate IMRT plan with this new framework is less than 1 s. This indicates that the GPU-based FSPB algorithm is well suited for online re-planning for adaptive radiotherapy. PMID:19794244

  16. 40 CFR Appendix A to Part 197 - Calculation of Annual Committed Effective Dose Equivalent

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Calculation of Annual Committed Effective Dose Equivalent A Appendix A to Part 197 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) RADIATION PROTECTION PROGRAMS PUBLIC HEALTH AND ENVIRONMENTAL RADIATION PROTECTION STANDARDS FOR YUCCA MOUNTAIN, NEVADA Pt. 197, App....

  17. [Calculation of the dose of low-intensity laser radiation: the need or the harm?].

    PubMed

    Moskvin, S V

    2012-01-01

    This study showed that it is highly undesirable to equip the devices for laser therapy with the dose-calculation function. In order to avoid mistakes, the operator should perform a strict sequence of actions as follows: to choose the needed wavelength and operating regime (the laser head block) of the LILR source, to set and measure the radiation power, the time and frequency of treatment, turn on the apparatus, control its operation and switch it off at the scheduled time. Meeting all these requirements eventually ensures obtaining a certain optimal dose density and guarantees that the entire procedure of laser irradiation is performed in a proper way. The equipment of the apparatus with the dose-calculation function is nothing more than a marketing ploy intended to earn extra money that apart from everything else creates additional problems for the customer. PMID:23373298

  18. Individual Dose Calculations with Use of the Revised Techa River Dosimetry System TRDS-2009D

    SciTech Connect

    Degteva, M. O.; Shagina, N. B.; Tolstykh, E. I.; Vorobiova, M. I.; Anspaugh, L. R.; Napier, Bruce A.

    2009-10-23

    An updated deterministic version of the Techa River Dosimetry System (TRDS-2009D) has been developed to estimate individual doses from external exposure and intake of radionuclides for residents living on the Techa River contaminated as a result of radioactive releases from the Mayak plutonium facility in 1949–1956. The TRDS-2009D is designed as a flexible system that uses, depending on the input data for an individual, various elements of system databases to provide the dosimetric variables requested by the user. Several phases are included in the computation schedule. The first phase includes calculations with use of a common protocol for all cohort members based on village-average-intake functions and external dose rates; individual data on age, gender and history of residence are included in the first phase. This phase results in dose estimates similar to those obtained with system TRDS-2000 used previously to derive risks of health effects in the Techa River Cohort. The second phase includes refinement of individual internal doses for those persons who have had body-burden measurements or exposure parameters specific to the household where he/she lived on the Techa River. The third phase includes summation of individual doses from environmental exposure and from radiological examinations. The results of TRDS-2009D dose calculations have demonstrated for the ETRC members on average a moderate increase in RBM dose estimates (34%) and a minor increase (5%) in estimates of stomach dose. The calculations for the members of the ETROC indicated similar small changes for stomach, but significant increase in RBM doses (400%). Individual-dose assessments performed with use of TRDS-2009D have been provided to epidemiologists for exploratory risk analysis in the ETRC and ETROC. These data provide an opportunity to evaluate the possible impact on radiogenic risk of such factors as confounding exposure (environmental and medical), changes in the Techa River source

  19. Algorithms used in heterogeneous dose calculations show systematic differences as measured with the Radiological Physics Center’s anthropomorphic thorax phantom used for RTOG credentialing

    PubMed Central

    Kry, Stephen F.; Alvarez, Paola; Molineu, Andrea; Amador, Carrie; Galvin, James; Followill, David S.

    2012-01-01

    Purpose To determine the impact of treatment planning algorithm on the accuracy of heterogeneous dose calculations in the Radiological Physics Center (RPC) thorax phantom. Methods and Materials We retrospectively analyzed the results of 304 irradiations of the RPC thorax phantom at 221 different institutions as part of credentialing for RTOG clinical trials; the irradiations were all done using 6-MV beams. Treatment plans included those for intensity-modulated radiation therapy (IMRT) as well as 3D conformal therapy (3D CRT). Heterogeneous plans were developed using Monte Carlo (MC), convolution/superposition (CS) and the anisotropic analytic algorithm (AAA), as well as pencil beam (PB) algorithms. For each plan and delivery, the absolute dose measured in the center of a lung target was compared to the calculated dose, as was the planar dose in 3 orthogonal planes. The difference between measured and calculated dose was examined as a function of planning algorithm as well as use of IMRT. Results PB algorithms overestimated the dose delivered to the center of the target by 4.9% on average. Surprisingly, CS algorithms and AAA also showed a systematic overestimation of the dose to the center of the target, by 3.7% on average. In contrast, the MC algorithm dose calculations agreed with measurement within 0.6% on average. There was no difference observed between IMRT and 3D CRT calculation accuracy. Conclusion Unexpectedly, advanced treatment planning systems (those using CS and AAA algorithms) overestimated the dose that was delivered to the lung target. This issue requires attention in terms of heterogeneity calculations and potentially in terms of clinical practice. PMID:23237006

  20. Modeling of Total Ionizing Dose Effects in Advanced Complementary Metal-Oxide-Semiconductor Technologies

    NASA Astrophysics Data System (ADS)

    Sanchez Esqueda, Ivan

    2011-12-01

    The increased use of commercial complementary metal-oxide-semiconductor (CMOS) technologies in harsh radiation environments has resulted in a new approach to radiation effects mitigation. This approach utilizes simulation to support the design of integrated circuits (ICs) to meet targeted tolerance specifications. Modeling the deleterious impact of ionizing radiation on ICs fabricated in advanced CMOS technologies requires understanding and analyzing the basic mechanisms that result in buildup of radiation-induced defects in specific sensitive regions. Extensive experimental studies have demonstrated that the sensitive regions are shallow trench isolation (STI) oxides. Nevertheless, very little work has been done to model the physical mechanisms that result in the buildup of radiation-induced defects and the radiation response of devices fabricated in these technologies. A comprehensive study of the physical mechanisms contributing to the buildup of radiation-induced oxide trapped charges and the generation of interface traps in advanced CMOS devices is presented in this dissertation. The basic mechanisms contributing to the buildup of radiation-induced defects are explored using a physical model that utilizes kinetic equations that captures total ionizing dose (TID) and dose rate effects in silicon dioxide (SiO2). These mechanisms are formulated into analytical models that calculate oxide trapped charge density (Not) and interface trap density (Nit) in sensitive regions of deep-submicron devices. Experiments performed on field-oxide-field-effect-transistors (FOXFETs) and metal-oxide-semiconductor (MOS) capacitors permit investigating TID effects and provide a comparison for the radiation response of advanced CMOS devices. When used in conjunction with closed-form expressions for surface potential, the analytical models enable an accurate description of radiation-induced degradation of transistor electrical characteristics. In this dissertation, the incorporation

  1. GPU-based fast Monte Carlo simulation for radiotherapy dose calculation.

    PubMed

    Jia, Xun; Gu, Xuejun; Graves, Yan Jiang; Folkerts, Michael; Jiang, Steve B

    2011-11-21

    Monte Carlo (MC) simulation is commonly considered to be the most accurate dose calculation method in radiotherapy. However, its efficiency still requires improvement for many routine clinical applications. In this paper, we present our recent progress toward the development of a graphics processing unit (GPU)-based MC dose calculation package, gDPM v2.0. It utilizes the parallel computation ability of a GPU to achieve high efficiency, while maintaining the same particle transport physics as in the original dose planning method (DPM) code and hence the same level of simulation accuracy. In GPU computing, divergence of execution paths between threads can considerably reduce the efficiency. Since photons and electrons undergo different physics and hence attain different execution paths, we use a simulation scheme where photon transport and electron transport are separated to partially relieve the thread divergence issue. A high-performance random number generator and a hardware linear interpolation are also utilized. We have also developed various components to handle the fluence map and linac geometry, so that gDPM can be used to compute dose distributions for realistic IMRT or VMAT treatment plans. Our gDPM package is tested for its accuracy and efficiency in both phantoms and realistic patient cases. In all cases, the average relative uncertainties are less than 1%. A statistical t-test is performed and the dose difference between the CPU and the GPU results is not found to be statistically significant in over 96% of the high dose region and over 97% of the entire region. Speed-up factors of 69.1 ∼ 87.2 have been observed using an NVIDIA Tesla C2050 GPU card against a 2.27 GHz Intel Xeon CPU processor. For realistic IMRT and VMAT plans, MC dose calculation can be completed with less than 1% standard deviation in 36.1 ∼ 39.6 s using gDPM. PMID:22016026

  2. Dose calculations using artificial neural networks: A feasibility study for photon beams

    NASA Astrophysics Data System (ADS)

    Vasseur, Aurélien; Makovicka, Libor; Martin, Éric; Sauget, Marc; Contassot-Vivier, Sylvain; Bahi, Jacques

    2008-04-01

    Direct dose calculations are a crucial requirement for Treatment Planning Systems. Some methods, such as Monte Carlo, explicitly model particle transport, others depend upon tabulated data or analytic formulae. However, their computation time is too lengthy for clinical use, or accuracy is insufficient, especially for recent techniques such as Intensity-Modulated Radiotherapy. Based on artificial neural networks (ANNs), a new solution is proposed and this work extends the properties of such an algorithm and is called NeuRad. Prior to any calculations, a first phase known as the learning process is necessary. Monte Carlo dose distributions in homogeneous media are used, and the ANN is then acquired. According to the training base, it can be used as a dose engine for either heterogeneous media or for an unknown material. In this report, two networks were created in order to compute dose distribution within a homogeneous phantom made of an unknown material and within an inhomogeneous phantom made of water and TA6V4 (titanium alloy corresponding to hip prosthesis). All NeuRad results were compared to Monte Carlo distributions. The latter required about 7 h on a dedicated cluster (10 nodes). NeuRad learning requires between 8 and 18 h (depending upon the size of the training base) on a single low-end computer. However, the results of dose computation with the ANN are available in less than 2 s, again using a low-end computer, for a 150×1×150 voxels phantom. In the case of homogeneous medium, the mean deviation in the high dose region was less than 1.7%. With a TA6V4 hip prosthesis bathed in water, the mean deviation in the high dose region was less than 4.1%. Further improvements in NeuRad will have to include full 3D calculations, inhomogeneity management and input definitions.

  3. GPU-based fast Monte Carlo dose calculation for proton therapy

    PubMed Central

    Jia, Xun; Schümann, Jan; Paganetti, Harald; Jiang, Steve B

    2015-01-01

    Accurate radiation dose calculation is essential for successful proton radiotherapy. Monte Carlo (MC) simulation is considered to be the most accurate method. However, the long computation time limits it from routine clinical applications. Recently, graphics processing units (GPUs) have been widely used to accelerate computationally intensive tasks in radiotherapy. We have developed a fast MC dose calculation package, gPMC, for proton dose calculation on a GPU. In gPMC, proton transport is modeled by the class II condensed history simulation scheme with a continuous slowing down approximation. Ionization, elastic and inelastic proton nucleus interactions are considered. Energy straggling and multiple scattering are modeled. Secondary electrons are not transported and their energies are locally deposited. After an inelastic nuclear interaction event, a variety of products are generated using an empirical model. Among them, charged nuclear fragments are terminated with energy locally deposited. Secondary protons are stored in a stack and transported after finishing transport of the primary protons, while secondary neutral particles are neglected. gPMC is implemented on the GPU under the CUDA platform. We have validated gPMC using the TOPAS/Geant4 MC code as the gold standard. For various cases including homogeneous and inhomogeneous phantoms as well as a patient case, good agreements between gPMC and TOPAS/Geant4 are observed. The gamma passing rate for the 2%/2 mm criterion is over 98.7% in the region with dose greater than 10% maximum dose in all cases, excluding low-density air regions. With gPMC it takes only 6–22 s to simulate 10 million source protons to achieve ~1% relative statistical uncertainty, depending on the phantoms and energy. This is an extremely high efficiency compared to the computational time of tens of CPU hours for TOPAS/Geant4. Our fast GPU-based code can thus facilitate the routine use of MC dose calculation in proton therapy. PMID:23128424

  4. GPU-based fast Monte Carlo dose calculation for proton therapy.

    PubMed

    Jia, Xun; Schümann, Jan; Paganetti, Harald; Jiang, Steve B

    2012-12-01

    Accurate radiation dose calculation is essential for successful proton radiotherapy. Monte Carlo (MC) simulation is considered to be the most accurate method. However, the long computation time limits it from routine clinical applications. Recently, graphics processing units (GPUs) have been widely used to accelerate computationally intensive tasks in radiotherapy. We have developed a fast MC dose calculation package, gPMC, for proton dose calculation on a GPU. In gPMC, proton transport is modeled by the class II condensed history simulation scheme with a continuous slowing down approximation. Ionization, elastic and inelastic proton nucleus interactions are considered. Energy straggling and multiple scattering are modeled. Secondary electrons are not transported and their energies are locally deposited. After an inelastic nuclear interaction event, a variety of products are generated using an empirical model. Among them, charged nuclear fragments are terminated with energy locally deposited. Secondary protons are stored in a stack and transported after finishing transport of the primary protons, while secondary neutral particles are neglected. gPMC is implemented on the GPU under the CUDA platform. We have validated gPMC using the TOPAS/Geant4 MC code as the gold standard. For various cases including homogeneous and inhomogeneous phantoms as well as a patient case, good agreements between gPMC and TOPAS/Geant4 are observed. The gamma passing rate for the 2%/2 mm criterion is over 98.7% in the region with dose greater than 10% maximum dose in all cases, excluding low-density air regions. With gPMC it takes only 6-22 s to simulate 10 million source protons to achieve ∼1% relative statistical uncertainty, depending on the phantoms and energy. This is an extremely high efficiency compared to the computational time of tens of CPU hours for TOPAS/Geant4. Our fast GPU-based code can thus facilitate the routine use of MC dose calculation in proton therapy. PMID

  5. GPU-based fast Monte Carlo dose calculation for proton therapy

    NASA Astrophysics Data System (ADS)

    Jia, Xun; Schümann, Jan; Paganetti, Harald; Jiang, Steve B.

    2012-12-01

    Accurate radiation dose calculation is essential for successful proton radiotherapy. Monte Carlo (MC) simulation is considered to be the most accurate method. However, the long computation time limits it from routine clinical applications. Recently, graphics processing units (GPUs) have been widely used to accelerate computationally intensive tasks in radiotherapy. We have developed a fast MC dose calculation package, gPMC, for proton dose calculation on a GPU. In gPMC, proton transport is modeled by the class II condensed history simulation scheme with a continuous slowing down approximation. Ionization, elastic and inelastic proton nucleus interactions are considered. Energy straggling and multiple scattering are modeled. Secondary electrons are not transported and their energies are locally deposited. After an inelastic nuclear interaction event, a variety of products are generated using an empirical model. Among them, charged nuclear fragments are terminated with energy locally deposited. Secondary protons are stored in a stack and transported after finishing transport of the primary protons, while secondary neutral particles are neglected. gPMC is implemented on the GPU under the CUDA platform. We have validated gPMC using the TOPAS/Geant4 MC code as the gold standard. For various cases including homogeneous and inhomogeneous phantoms as well as a patient case, good agreements between gPMC and TOPAS/Geant4 are observed. The gamma passing rate for the 2%/2 mm criterion is over 98.7% in the region with dose greater than 10% maximum dose in all cases, excluding low-density air regions. With gPMC it takes only 6-22 s to simulate 10 million source protons to achieve ˜1% relative statistical uncertainty, depending on the phantoms and energy. This is an extremely high efficiency compared to the computational time of tens of CPU hours for TOPAS/Geant4. Our fast GPU-based code can thus facilitate the routine use of MC dose calculation in proton therapy.

  6. Advances in metered dose inhaler technology: hardware development.

    PubMed

    Stein, Stephen W; Sheth, Poonam; Hodson, P David; Myrdal, Paul B

    2014-04-01

    Pressurized metered dose inhalers (MDIs) were first introduced in the 1950s and they are currently widely prescribed as portable systems to treat pulmonary conditions. MDIs consist of a formulation containing dissolved or suspended drug and hardware needed to contain the formulation and enable efficient and consistent dose delivery to the patient. The device hardware includes a canister that is appropriately sized to contain sufficient formulation for the required number of doses, a metering valve capable of delivering a consistent amount of drug with each dose delivered, an actuator mouthpiece that atomizes the formulation and serves as a conduit to deliver the aerosol to the patient, and often an indicating mechanism that provides information to the patient on the number of doses remaining. This review focuses on the current state-of-the-art of MDI hardware and includes discussion of enhancements made to the device's core subsystems. In addition, technologies that aid the correct use of MDIs will be discussed. These include spacers, valved holding chambers, and breath-actuated devices. Many of the improvements discussed in this article increase the ability of MDI systems to meet regulatory specifications. Innovations that enhance the functionality of MDIs continue to be balanced by the fact that a key advantage of MDI systems is their low cost per dose. The expansion of the health care market in developing countries and the increased focus on health care costs in many developed countries will ensure that MDIs remain a cost-effective crucial delivery system for treating pulmonary conditions for many years to come. PMID:24357110

  7. Neutron spectra and dose equivalents calculated in tissue for high-energy radiation therapy

    SciTech Connect

    Kry, Stephen F.; Howell, Rebecca M.; Salehpour, Mohammad; Followill, David S.

    2009-04-15

    Neutrons are by-products of high-energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient's risk of radiation-induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high-energy radiation therapy as a function of their depth in tissue and for different field sizes and different source-to-surface distances (SSD). We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth-dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in-air conditions. Alternately, an appropriate percent depth-dose equivalent curve should be

  8. Mathematical child phantom for the calculation of dose to the organs at risk

    SciTech Connect

    Francois, P.; Beurtheret, C.; Dutreix, A.; De Vathaire, F.

    1988-05-01

    In order to calculate the doses received by the organs of 530 children treated by radiation for cancer between 1945 and 1969 at the G. Roussy Institute, we have developed a computer program for organ location calculation. To calculate the location of each child's organs of interest at the time of the treatment, only two parameters are necessary; sex and height or sex and age when the height at the time of the treatment is unknown. The algorithm is based on the metric studies of growth known as auxology. Each organ is located by one point representing its center. The model has been checked on 100 healthy children.

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

    SciTech Connect

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

    2014-06-15

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

  10. A graphical user interface for calculation of 3D dose distribution using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Chow, J. C. L.; Leung, M. K. K.

    2008-02-01

    A software graphical user interface (GUI) for calculation of 3D dose distribution using Monte Carlo (MC) simulation is developed using MATLAB. This GUI (DOSCTP) provides a user-friendly platform for DICOM CT-based dose calculation using EGSnrcMP-based DOSXYZnrc code. It offers numerous features not found in DOSXYZnrc, such as the ability to use multiple beams from different phase-space files, and has built-in dose analysis and visualization tools. DOSCTP is written completely in MATLAB, with integrated access to DOSXYZnrc and CTCREATE. The program function may be divided into four subgroups, namely, beam placement, MC simulation with DOSXYZnrc, dose visualization, and export. Each is controlled by separate routines. The verification of DOSCTP was carried out by comparing plans with different beam arrangements (multi-beam/photon arc) on an inhomogeneous phantom as well as patient CT between the GUI and Pinnacle3. DOSCTP was developed and verified with the following features: (1) a built-in voxel editor to modify CT-based DOSXYZnrc phantoms for research purposes; (2) multi-beam placement is possible, which cannot be achieved using the current DOSXYZnrc code; (3) the treatment plan, including the dose distributions, contours and image set can be exported to a commercial treatment planning system such as Pinnacle3 or to CERR using RTOG format for plan evaluation and comparison; (4) a built-in RTOG-compatible dose reviewer for dose visualization and analysis such as finding the volume of hot/cold spots in the 3D dose distributions based on a user threshold. DOSCTP greatly simplifies the use of DOSXYZnrc and CTCREATE, and offers numerous features that not found in the original user-code. Moreover, since phase-space beams can be defined and generated by the user, it is a particularly useful tool to carry out plans using specifically designed irradiators/accelerators that cannot be found in the Linac library of commercial treatment planning systems.

  11. Modelling lateral beam quality variations in pencil kernel based photon dose calculations

    NASA Astrophysics Data System (ADS)

    Nyholm, T.; Olofsson, J.; Ahnesjö, A.; Karlsson, M.

    2006-08-01

    Standard treatment machines for external radiotherapy are designed to yield flat dose distributions at a representative treatment depth. The common method to reach this goal is to use a flattening filter to decrease the fluence in the centre of the beam. A side effect of this filtering is that the average energy of the beam is generally lower at a distance from the central axis, a phenomenon commonly referred to as off-axis softening. The off-axis softening results in a relative change in beam quality that is almost independent of machine brand and model. Central axis dose calculations using pencil beam kernels show no drastic loss in accuracy when the off-axis beam quality variations are neglected. However, for dose calculated at off-axis positions the effect should be considered, otherwise errors of several per cent can be introduced. This work proposes a method to explicitly include the effect of off-axis softening in pencil kernel based photon dose calculations for arbitrary positions in a radiation field. Variations of pencil kernel values are modelled through a generic relation between half value layer (HVL) thickness and off-axis position for standard treatment machines. The pencil kernel integration for dose calculation is performed through sampling of energy fluence and beam quality in sectors of concentric circles around the calculation point. The method is fully based on generic data and therefore does not require any specific measurements for characterization of the off-axis softening effect, provided that the machine performance is in agreement with the assumed HVL variations. The model is verified versus profile measurements at different depths and through a model self-consistency check, using the dose calculation model to estimate HVL values at off-axis positions. A comparison between calculated and measured profiles at different depths showed a maximum relative error of 4% without explicit modelling of off-axis softening. The maximum relative error

  12. Dose differences in intensity-modulated radiotherapy plans calculated with pencil beam and Monte Carlo for lung SBRT.

    PubMed

    Liu, Han; Zhuang, Tingliang; Stephans, Kevin; Videtic, Gregory; Raithel, Stephen; Djemil, Toufik; Xia, Ping

    2015-01-01

    For patients with medically inoperable early-stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy, early treatment plans were based on a simpler dose calculation algorithm, the pencil beam (PB) calculation. Because these patients had the longest treatment follow-up, identifying dose differences between the PB calculated dose and Monte Carlo calculated dose is clinically important for understanding of treatment outcomes. Previous studies found significant dose differences between the PB dose calculation and more accurate dose calculation algorithms, such as convolution-based or Monte Carlo (MC), mostly for three-dimensional conformal radiotherapy (3D CRT) plans. The aim of this study is to investigate whether these observed dose differences also exist for intensity-modulated radiotherapy (IMRT) plans for both centrally and peripherally located tumors. Seventy patients (35 central and 35 peripheral) were retrospectively selected for this study. The clinical IMRT plans that were initially calculated with the PB algorithm were recalculated with the MC algorithm. Among these paired plans, dosimetric parameters were compared for the targets and critical organs. When compared to MC calculation, PB calculation overestimated doses to the planning target volumes (PTVs) of central and peripheral tumors with different magnitudes. The doses to 95% of the central and peripheral PTVs were overestimated by 9.7% ± 5.6% and 12.0% ± 7.3%, respectively. This dose overestimation did not affect doses to the critical organs, such as the spinal cord and lung. In conclusion, for NSCLC treated with IMRT, dose differences between the PB and MC calculations were different from that of 3D CRT. No significant dose differences in critical organs were observed between the two calculations. PMID:26699560

  13. Review of dynamical models for external dose calculations based on Monte Carlo simulations in urbanised areas.

    PubMed

    Eged, Katalin; Kis, Zoltán; Voigt, Gabriele

    2006-01-01

    After an accidental release of radionuclides to the inhabited environment the external gamma irradiation from deposited radioactivity contributes significantly to the radiation exposure of the population for extended periods. For evaluating this exposure pathway, three main model requirements are needed: (i) to calculate the air kerma value per photon emitted per unit source area, based on Monte Carlo (MC) simulations; (ii) to describe the distribution and dynamics of radionuclides on the diverse urban surfaces; and (iii) to combine all these elements in a relevant urban model to calculate the resulting doses according to the actual scenario. This paper provides an overview about the different approaches to calculate photon transport in urban areas and about several dose calculation codes published. Two types of Monte Carlo simulations are presented using the global and the local approaches of photon transport. Moreover, two different philosophies of the dose calculation, the "location factor method" and a combination of relative contamination of surfaces with air kerma values are described. The main features of six codes (ECOSYS, EDEM2M, EXPURT, PARATI, TEMAS, URGENT) are highlighted together with a short model-model features intercomparison. PMID:16095771

  14. A Monte Carlo evaluation of RapidArc dose calculations for oropharynx radiotherapy

    NASA Astrophysics Data System (ADS)

    Gagne, I. M.; Ansbacher, W.; Zavgorodni, S.; Popescu, C.; Beckham, W. A.

    2008-12-01

    RapidArc™, recently released by Varian Medical Systems, is a novel extension of IMRT in which an optimized 3D dose distribution may be delivered in a single gantry rotation of 360° or less. The purpose of this study was to investigate the accuracy of the analytical anisotropic algorithm (AAA), the sole algorithm for photon dose calculations of RapidArc™ treatment plans. The clinical site chosen was oropharynx and the associated nodes involved. The VIMC-Arc system, which utilizes BEAMnrc and DOSXYZnrc for particle transport through the linac head and patient CT phantom, was used as a benchmarking tool. As part of this study, the dose for a single static aperture, typical for RapidArc™ delivery, was calculated by the AAA, MC and compared with the film. This film measurement confirmed MC modeling of the beam aperture in water. It also demonstrated that the AAA dosimetric error can be as high as 12% near isolated leaf edges and up to 5% at the leaf end. The composite effect of these errors in a full RapidArc™ calculation in water involving a C-shaped target and the associated organ at risk produced a 1.5% overprediction of the mean target dose. In our cohort of six patients, the AAA was found, on average, to overestimate the PTV60 coverage at the 95% level in the presence of air cavities by 1.0% (SD = 1.1%). Removing the air cavities from the target volumes reduced these differences by about a factor of 2. The dose to critical structures was also overestimated by the AAA. The mean dose to the spinal cord was higher by 1.8% (SD = 0.8%), while the effective maximum dose (D2%) was only 0.2% higher (SD = 0.6%). The mean dose to the parotid glands was overestimated by ~9%. This study has shown that the accuracy of the AAA for RapidArc™ dose calculations, performed at a resolution of 2.5 mm or better, is adequate for clinical use.

  15. A Monte Carlo evaluation of RapidArc dose calculations for oropharynx radiotherapy.

    PubMed

    Gagne, I M; Ansbacher, W; Zavgorodni, S; Popescu, C; Beckham, W A

    2008-12-21

    RapidArc, recently released by Varian Medical Systems, is a novel extension of IMRT in which an optimized 3D dose distribution may be delivered in a single gantry rotation of 360 degrees or less. The purpose of this study was to investigate the accuracy of the analytical anisotropic algorithm (AAA), the sole algorithm for photon dose calculations of RapidArc treatment plans. The clinical site chosen was oropharynx and the associated nodes involved. The VIMC-Arc system, which utilizes BEAMnrc and DOSXYZnrc for particle transport through the linac head and patient CT phantom, was used as a benchmarking tool. As part of this study, the dose for a single static aperture, typical for RapidArc delivery, was calculated by the AAA, MC and compared with the film. This film measurement confirmed MC modeling of the beam aperture in water. It also demonstrated that the AAA dosimetric error can be as high as 12% near isolated leaf edges and up to 5% at the leaf end. The composite effect of these errors in a full RapidArc calculation in water involving a C-shaped target and the associated organ at risk produced a 1.5% overprediction of the mean target dose. In our cohort of six patients, the AAA was found, on average, to overestimate the PTV60 coverage at the 95% level in the presence of air cavities by 1.0% (SD = 1.1%). Removing the air cavities from the target volumes reduced these differences by about a factor of 2. The dose to critical structures was also overestimated by the AAA. The mean dose to the spinal cord was higher by 1.8% (SD = 0.8%), while the effective maximum dose (D2%) was only 0.2% higher (SD = 0.6%). The mean dose to the parotid glands was overestimated by approximately 9%. This study has shown that the accuracy of the AAA for RapidArc dose calculations, performed at a resolution of 2.5 mm or better, is adequate for clinical use. PMID:19033640

  16. A comparison of Monte Carlo and model-based dose calculations in radiotherapy using MCNPTV

    NASA Astrophysics Data System (ADS)

    Wyatt, Mark S.; Miller, Laurence F.

    2006-06-01

    Monte Carlo calculations for megavoltage radiotherapy beams represent the next generation of dose calculation in the clinical environment. In this paper, calculations obtained by the MCNP code based on CT data from a human pelvis are compared against those obtained by a commercial radiotherapy treatment system (CMS XiO). The MCNP calculations are automated by the use of MCNPTV (MCNP Treatment Verification), an integrated application developed in Visual Basic that runs on a Windows-based PC. The linear accelerator beam is modeled as a finite point source, and validated by comparing depth dose curves and lateral profiles in a water phantom to measured data. Calculated water phantom PDDs are within 1% of measured data, but the lateral profiles exhibit differences of 2.4, 5.5, and 5.7 mm at the 60%, 40%, and 20% isodose lines, respectively. A MCNP calculation is performed using the CT data and 15 points are selected for comparison with XiO. Results are generally within the uncertainty of the MCNP calculation, although differences up to 13.2% are seen in the presence of large heterogeneities.

  17. Dosimetric evaluation of photon dose calculation under jaw and MLC shielding

    SciTech Connect

    Fogliata, A.; Clivio, A.; Vanetti, E.; Nicolini, G.; Belosi, M. F.; Cozzi, L.

    2013-10-15

    Purpose: The accuracy of photon dose calculation algorithms in out-of-field regions is often neglected, despite its importance for organs at risk and peripheral dose evaluation. The present work has assessed this for the anisotropic analytical algorithm (AAA) and the Acuros-XB algorithms implemented in the Eclipse treatment planning system. Specifically, the regions shielded by the jaw, or the MLC, or both MLC and jaw for flattened and unflattened beams have been studied.Methods: The accuracy in out-of-field dose under different conditions was studied for two different algorithms. Measured depth doses out of the field, for different field sizes and various distances from the beam edge were compared with the corresponding AAA and Acuros-XB calculations in water. Four volumetric modulated arc therapy plans (in the RapidArc form) were optimized in a water equivalent phantom, PTW Octavius, to obtain a region always shielded by the MLC (or MLC and jaw) during the delivery. Doses to different points located in the shielded region and in a target-like structure were measured with an ion chamber, and results were compared with the AAA and Acuros-XB calculations. Photon beams of 6 and 10 MV, flattened and unflattened were used for the tests.Results: Good agreement between calculated and measured depth doses was found using both algorithms for all points measured at depth greater than 3 cm. The mean dose differences (±1SD) were −8%± 16%, −3%± 15%, −16%± 18%, and −9%± 16% for measurements vs AAA calculations and −10%± 14%, −5%± 12%, −19%± 17%, and −13%± 14% for Acuros-XB, for 6X, 6 flattening-filter free (FFF), 10X, and 10FFF beams, respectively. The same figures for dose differences relative to the open beam central axis dose were: −0.1%± 0.3%, 0.0%± 0.4%, −0.3%± 0.3%, and −0.1%± 0.3% for AAA and −0.2%± 0.4%, −0.1%± 0.4%, −0.5%± 0.5%, and −0.3%± 0.4% for Acuros-XB. Buildup dose was overestimated with AAA, while Acuros-XB gave

  18. Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition

    SciTech Connect

    Landry, Guillaume; Reniers, Brigitte; Murrer, Lars; Lutgens, Ludy; Bloemen-Van Gurp, Esther; Pignol, Jean-Philippe; Keller, Brian; Beaulieu, Luc; Verhaegen, Frank

    2010-10-15

    Purpose: The objective of this work is to assess the sensitivity of Monte Carlo (MC) dose calculations to uncertainties in human tissue composition for a range of low photon energy brachytherapy sources: {sup 125}I, {sup 103}Pd, {sup 131}Cs, and an electronic brachytherapy source (EBS). The low energy photons emitted by these sources make the dosimetry sensitive to variations in tissue atomic number due to the dominance of the photoelectric effect. This work reports dose to a small mass of water in medium D{sub w,m} as opposed to dose to a small mass of medium in medium D{sub m,m}. Methods: Mean adipose, mammary gland, and breast tissues (as uniform mixture of the aforementioned tissues) are investigated as well as compositions corresponding to one standard deviation from the mean. Prostate mean compositions from three different literature sources are also investigated. Three sets of MC simulations are performed with the GEANT4 code: (1) Dose calculations for idealized TG-43-like spherical geometries using point sources. Radial dose profiles obtained in different media are compared to assess the influence of compositional uncertainties. (2) Dose calculations for four clinical prostate LDR brachytherapy permanent seed implants using {sup 125}I seeds (Model 2301, Best Medical, Springfield, VA). The effect of varying the prostate composition in the planning target volume (PTV) is investigated by comparing PTV D{sub 90} values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using {sup 103}Pd seeds (Model 2335, Best Medical). The effects of varying the adipose/gland ratio in the PTV and of varying the elemental composition of adipose and gland within one standard deviation of the assumed mean composition are investigated by comparing PTV D{sub 90} values. For (2) and (3), the influence of using the mass density from CT scans instead of unit mass density is also assessed. Results: Results from simulation (1) show that variations

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

    NASA Astrophysics Data System (ADS)

    Kramer, Richard

    2011-08-01

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

  20. Neutron dose calculation at the maze entrance of medical linear accelerator rooms.

    PubMed

    Falcão, R C; Facure, A; Silva, A X

    2007-01-01

    Currently, teletherapy machines of cobalt and caesium are being replaced by linear accelerators. The maximum photon energy in these machines can vary from 4 to 25 MeV, and one of the great advantages of these equipments is that they do not have a radioactive source incorporated. High-energy (E > 10 MV) medical linear accelerators offer several physical advantages over lower energy ones: the skin dose is lower, the beam is more penetrating, and the scattered dose to tissues outside the target volume is smaller. Nevertheless, the contamination of undesirable neutrons in the therapeutic beam, generated by the high-energy photons, has become an additional problem as long as patient protection and occupational doses are concerned. The treatment room walls are shielded to attenuate the primary and secondary X-ray fluence, and this shielding is generally adequate to attenuate the neutrons. However, these neutrons are scattered through the treatment room maze and may result in a radiological problem at the door entrance, a high occupancy area in a radiotherapy facility. In this article, we used MCNP Monte Carlo simulation to calculate neutron doses in the maze of radiotherapy rooms and we suggest an alternative method to the Kersey semi-empirical model of neutron dose calculation at the entrance of mazes. It was found that this new method fits better measured values found in literature, as well as our Monte Carlo simulated ones. PMID:17005540

  1. Sex-specific tissue weighting factors for effective dose equivalent calculations

    SciTech Connect

    Xu, X.G.; Reece, W.D.

    1996-01-01

    The effective dose equivalent was defined in the International Commission on Radiological Protection Publication 26 in 1977 and later adopted by the U.S. Nuclear REgulatory Commission. To calculate organ doses and effective dose equivalent for external exposures using Monte Carlo simulations, sex-specific anthropomorphic phantoms and sex-specific weighting factors are always employed. This paper presents detailed mathematical derivation of a set of sex-specific tissue weighting factors and the conditions which the weighting factors must satisfy. Results of effective dose equivalent calculations using female and male phantoms exposed to monoenergetic photon beams of 0.08, 0.3, and 1.0 MeV are provided and compared with results published by other authors using different sex-specific weighting factors and phantoms. The results indicate that females always receive higher effective dose equivalent than males for the photon energies and geometries considered and that some published data may be wrong due to mistakes in deriving the sex-specific weighting factors. 17 refs., 2 figs., 2 tabs.

  2. Skin dose calculations for uranium fuel particles below 500 microns in diameter.

    PubMed

    Pöllänen, R; Toivonen, H

    1995-03-01

    Two different methods for skin dose calculations, VARSKIN Mod 2 and PSS are compared for a spherical uranium fuel particle (diameter 1-500 microns) deposited on the skin. Nuclide-specific beta dose rate at different skin depths for a particle of unit activity is determined as a function of particle size. Both methods show that the effects of self-shielding must be included in the dose calculations for low and medium energy beta emitters. Skin dose rate is drastically overestimated when point source approximation is used. For high energy beta emitters (e.g., 90Y, 106Rh, and 144Pr) the volume source can be approximated as a point source. The difference in doses is then below 20% for particles up to 100 microns in diameter. The models give equal results deep in the skin (in terms of range of the beta particles). The reason is that the correction due to the diminished backscattering in air-tissue interface is insignificant at large distances. For three-dimensional sources the backscattering correction should be introduced in the VARSKIN Mod 2. PMID:7860313

  3. 4D SPECT/CT acquisition for 3D dose calculation and dose planning in (177)Lu-peptide receptor radionuclide therapy: applications for clinical routine.

    PubMed

    Kairemo, Kalevi; Kangasmäki, Aki

    2013-01-01

    Molecular radiotherapy combines the potential of a specific tracer (vector) targeting tumor cells with local radiotoxicity. Designing a specific tumor-targeting/killing combination is a tailoring process. Radionuclides with imaging capacity serve best in the selection of the targeting molecule. The potential of targeted therapy with radiolabeled peptides has been reported in many conditions; peptide receptor radionuclide therapy (PRRT) is already part of Scandinavian guidelines for treating neuroendocrine tumors. Lu-177- and Y-90-labeled somatostatin analogs, including DOTATOC, DOTANOC, and DOTATATE, are most the commonly used and have turned out to be effective. For routine use, an efficient, rapid, and reliable dose calculation tool is needed. In this chapter we describe how serial pre- and posttherapeutic scans can be used for dose calculation and for predicting therapy doses. Our software for radionuclide dose calculation is a three-dimensional, voxel-based system. The 3D dose calculation requires coregistered SPECT image sets from several time points after infusion to reconstruct time-activity curves for each voxel. Image registration is done directly by SPECT image registration using the first time point as a target. From the time-activity curves, initial activity and total half-life maps are calculated to produce a cumulated activity map. The cumulated activity map is then convoluted with a voxel-dose kernel to obtain a 3D dose map. We performed dose calculations similarly for both therapeutic and preplanning images. Preplanning dose was extrapolated to predict therapy dose using the ratio of administered activities. Our 3D dose calculation results are also compared with those of OLINDA. Our preliminary results indicate that dose planning using pretherapeutic scanning can predict critical organ and tumor doses. In some cases, the dose planning prediction resulted in slight, and slightly dose-dependent, overestimation of final therapy dose. Real tumor dose

  4. SU-E-J-87: Ventilation Weighting Effect On Mean Doses of Both Side Lungs for Patients with Advanced Stage Lung Cancer

    SciTech Connect

    Qu, H; Xia, P; Yu, N

    2015-06-15

    Purpose: To study ventilation weighting effect on radiation doses to both side lungs for patients with advanced stage lung cancer. Methods: Fourteen patients with advanced stage lung cancer were included in this retrospective study. Proprietary software was developed to calculate the lung ventilation map based on 4DCT images acquired for radiation therapy. Two phases of inhale (0%) and exhale (50%) were used for the lung ventilation calculations. For each patient, the CT images were resampled to the same dose calculation resolution of 3mmx3mmx3mm. The ventilation distribution was then normalized by the mean value of the ventilation. The ventilation weighted dose was calculated by applying linearly weighted ventilation to the dose of each pixel. The lung contours were automatically delineated from patient CT image with lung window, excluding the tumor and high density tissues. For contralateral and ipsilateral lungs, the mean lung doses from the original plan and ventilation weighted mean lung doses were compared using two tail t-Test. Results: The average of mean dose was 6.1 ±3.8Gy for the contralateral lungs, and 26.2 ± 14.0Gy for the ipsilateral lungs. The average of ventilation weighted dose was 6.3± 3.8Gy for the contralateral lungs and 24.6 ± 13.1Gy for the ipsilateral lungs. The statistics analysis shows the significance of the mean dose increase (p<0.015) for the contralateral lungs and decrease (p<0.005) for the ipsilateral lungs. Conclusion: Ventilation weighted doses were greater than the un-weighted doses for contralateral lungs and smaller for ipsilateral lungs. This Result may be helpful to understand the radiation dosimetric effect on the lung function and provide planning guidance for patients with advance stage lung cancer.

  5. 3D dose distribution calculation in a voxelized human phantom by means of Monte Carlo method.

    PubMed

    Abella, V; Miró, R; Juste, B; Verdú, G

    2010-01-01

    The aim of this work is to provide the reconstruction of a real human voxelized phantom by means of a MatLab program and the simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) (60)Co radiotherapy unit, by using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project results in 3D dose mapping calculations inside the voxelized antropomorphic head phantom. The program provides the voxelization by first processing the CT slices; the process follows a two-dimensional pixel and material identification algorithm on each slice and three-dimensional interpolation in order to describe the phantom geometry via small cubic cells, resulting in an MCNP input deck format output. Dose rates are calculated by using the MCNP5 tool FMESH, superimposed mesh tally, which gives the track length estimation of the particle flux in units of particles/cm(2). Furthermore, the particle flux is converted into dose by using the conversion coefficients extracted from the NIST Physical Reference Data. The voxelization using a three-dimensional interpolation technique in combination with the use of the FMESH tool of the MCNP Monte Carlo code offers an optimal simulation which results in 3D dose mapping calculations inside anthropomorphic phantoms. This tool is very useful in radiation treatment assessments, in which voxelized phantoms are widely utilized. PMID:19892556

  6. Monte Carlo-based dose calculation for 32P patch source for superficial brachytherapy applications

    PubMed Central

    Sahoo, Sridhar; Palani, Selvam T.; Saxena, S. K.; Babu, D. A. R.; Dash, A.

    2015-01-01

    Skin cancer treatment involving 32P source is an easy, less expensive method of treatment limited to small and superficial lesions of approximately 1 mm deep. Bhabha Atomic Research Centre (BARC) has indigenously developed 32P nafion-based patch source (1 cm × 1 cm) for treating skin cancer. For this source, the values of dose per unit activity at different depths including dose profiles in water are calculated using the EGSnrc-based Monte Carlo code system. For an initial activity of 1 Bq distributed in 1 cm2 surface area of the source, the calculated central axis depth dose values are 3.62 × 10-10 GyBq-1 and 8.41 × 10-11 GyBq-1at 0.0125 and 1 mm depths in water, respectively. Hence, the treatment time calculated for delivering therapeutic dose of 30 Gy at 1 mm depth along the central axis of the source involving 37 MBq activity is about 2.7 hrs. PMID:26150682

  7. Advancements in dynamic kill calculations for blowout wells

    SciTech Connect

    Kouba, G.E. . Production Fluids Div.); MacDougall, G.R. ); Schumacher, B.W. . Information Technology Dept.)

    1993-09-01

    This paper addresses the development, interpretation, and use of dynamic kill equations. To this end, three simple calculation techniques are developed for determining the minimum dynamic kill rate. Two techniques contain only single-phase calculations and are independent of reservoir inflow performance. Despite these limitations, these two methods are useful for bracketing the minimum flow rates necessary to kill a blowing well. For the third technique, a simplified mechanistic multiphase-flow model is used to determine a most-probable minimum kill rate.

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

    NASA Astrophysics Data System (ADS)

    Gu, Jianwei

    CT scanner models in this dissertation were versatile and accurate tools for estimating dose to different patient phantoms undergoing various CT procedures. The organ doses from kV and MV CBCT were also calculated. This dissertation finally summarizes areas where future research can be performed including MV CBCT further validation and application, dose reporting software and image and dose correlation study.

  9. Beyond Gaussians: a study of single-spot modeling for scanning proton dose calculation

    NASA Astrophysics Data System (ADS)

    Li, Yupeng; Zhu, Ronald X.; Sahoo, Narayan; Anand, Aman; Zhang, Xiaodong

    2012-02-01

    Active spot scanning proton therapy is becoming increasingly adopted by proton therapy centers worldwide. Unlike passive-scattering proton therapy, active spot scanning proton therapy, especially intensity-modulated proton therapy, requires proper modeling of each scanning spot to ensure accurate computation of the total dose distribution contributed from a large number of spots. During commissioning of the spot scanning gantry at the Proton Therapy Center in Houston, it was observed that the long-range scattering protons in a medium may have been inadequately modeled for high-energy beams by a commercial treatment planning system, which could lead to incorrect prediction of field size effects on dose output. In this study, we developed a pencil beam algorithm for scanning proton dose calculation by focusing on properly modeling individual scanning spots. All modeling parameters required by the pencil beam algorithm can be generated based solely on a few sets of measured data. We demonstrated that low-dose halos in single-spot profiles in the medium could be adequately modeled with the addition of a modified Cauchy-Lorentz distribution function to a double-Gaussian function. The field size effects were accurately computed at all depths and field sizes for all energies, and good dose accuracy was also achieved for patient dose verification. The implementation of the proposed pencil beam algorithm also enabled us to study the importance of different modeling components and parameters at various beam energies. The results of this study may be helpful in improving dose calculation accuracy and simplifying beam commissioning and treatment planning processes for spot scanning proton therapy

  10. Beyond Gaussians: a study of single spot modeling for scanning proton dose calculation

    PubMed Central

    Li, Yupeng; Zhu, Ronald X.; Sahoo, Narayan; Anand, Aman; Zhang, Xiaodong

    2013-01-01

    Active spot scanning proton therapy is becoming increasingly adopted by proton therapy centers worldwide. Unlike passive-scattering proton therapy, active spot scanning proton therapy, especially intensity-modulated proton therapy, requires proper modeling of each scanning spot to ensure accurate computation of the total dose distribution contributed from a large number of spots. During commissioning of the spot scanning gantry at the Proton Therapy Center in Houston, it was observed that the long-range scattering protons in a medium may have been inadequately modeled for high-energy beams by a commercial treatment planning system, which could lead to incorrect prediction of field-size effects on dose output. In the present study, we developed a pencil-beam algorithm for scanning-proton dose calculation by focusing on properly modeling individual scanning spots. All modeling parameters required by the pencil-beam algorithm can be generated based solely on a few sets of measured data. We demonstrated that low-dose halos in single-spot profiles in the medium could be adequately modeled with the addition of a modified Cauchy-Lorentz distribution function to a double-Gaussian function. The field-size effects were accurately computed at all depths and field sizes for all energies, and good dose accuracy was also achieved for patient dose verification. The implementation of the proposed pencil beam algorithm also enabled us to study the importance of different modeling components and parameters at various beam energies. The results of this study may be helpful in improving dose calculation accuracy and simplifying beam commissioning and treatment planning processes for spot scanning proton therapy. PMID:22297324

  11. Advanced Geometric Optics on a Programmable Pocket Calculator.

    ERIC Educational Resources Information Center

    Nussbaum, Allen

    1979-01-01

    Presents a ray-tracing procedure based on some ideas of Herzberger and the matrix approach to geometrical optics. This method, which can be implemented on a programmable pocket calculator, applies to any conic surface, including paraboloids, spheres, and planes. (Author/GA)

  12. Patient-specific Monte Carlo dose calculations for 103Pd breast brachytherapy

    NASA Astrophysics Data System (ADS)

    Miksys, N.; Cygler, J. E.; Caudrelier, J. M.; Thomson, R. M.

    2016-04-01

    This work retrospectively investigates patient-specific Monte Carlo (MC) dose calculations for 103Pd permanent implant breast brachytherapy, exploring various necessary assumptions for deriving virtual patient models: post-implant CT image metallic artifact reduction (MAR), tissue assignment schemes (TAS), and elemental tissue compositions. Three MAR methods (thresholding, 3D median filter, virtual sinogram) are applied to CT images; resulting images are compared to each other and to uncorrected images. Virtual patient models are then derived by application of different TAS ranging from TG-186 basic recommendations (mixed adipose and gland tissue at uniform literature-derived density) to detailed schemes (segmented adipose and gland with CT-derived densities). For detailed schemes, alternate mass density segmentation thresholds between adipose and gland are considered. Several literature-derived elemental compositions for adipose, gland and skin are compared. MC models derived from uncorrected CT images can yield large errors in dose calculations especially when used with detailed TAS. Differences in MAR method result in large differences in local doses when variations in CT number cause differences in tissue assignment. Between different MAR models (same TAS), PTV {{D}90} and skin {{D}1~\\text{c{{\\text{m}}3}}} each vary by up to 6%. Basic TAS (mixed adipose/gland tissue) generally yield higher dose metrics than detailed segmented schemes: PTV {{D}90} and skin {{D}1~\\text{c{{\\text{m}}3}}} are higher by up to 13% and 9% respectively. Employing alternate adipose, gland and skin elemental compositions can cause variations in PTV {{D}90} of up to 11% and skin {{D}1~\\text{c{{\\text{m}}3}}} of up to 30%. Overall, AAPM TG-43 overestimates dose to the PTV ({{D}90} on average 10% and up to 27%) and underestimates dose to the skin ({{D}1~\\text{c{{\\text{m}}3}}} on average 29% and up to 48%) compared to the various MC models derived using the post-MAR CT images studied

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

    PubMed

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

    2016-01-01

    Full Monte Carlo (FMC) calculation of dose distribution has been recognized to have superior accuracy, compared with the pencil beam algorithm (PBA). However, since the FMC methods require long calculation time, it is difficult to apply them to routine treatment planning at present. In order to improve the situation, a simplified Monte Carlo (SMC) method has been introduced to the dose kernel calculation applicable to dose optimization procedure for the proton pencil beam scanning. We have evaluated accuracy of the SMC calculation by comparing a result of the dose kernel calculation using the SMC method with that using the FMC method in an inhomogeneous phantom. The dose distribution obtained by the SMC method was in good agreement with that obtained by the FMC method. To assess the usefulness of SMC calculation in clinical situations, we have compared results of the dose calculation using the SMC with those using the PBA method for three clinical cases of tumor treatment. The dose distributions calculated with the PBA dose kernels appear to be homogeneous in the planning target volumes (PTVs). In practice, the dose distributions calculated with the SMC dose kernels with the spot weights optimized with the PBA method show largely inhomogeneous dose distributions in the PTVs, while those with the spot weights optimized with the SMC method have moderately homogeneous distributions in the PTVs. Calculation using the SMC method is faster than that using the GEANT4 by three orders of magnitude. In addition, the graphic processing unit (GPU) boosts the calculation speed by 13times for the treatment planning using the SMC method. Thence, the SMC method will be applicable to routine clinical treatment planning for reproduc-tion of the complex dose distribution more accurately than the PBA method in a reasonably short time by use of the GPU-based calculation engine. PMID:27074456

  14. Monte Carlo calculation of dose rate conversion factors for external exposure to photon emitters in soil.

    PubMed

    Clouvas, A; Xanthos, S; Antonopoulos-Domis, M; Silva, J

    2000-03-01

    The dose rate conversion factors D(CF) (absorbed dose rate in air per unit activity per unit of soil mass, nGy h(-1) per Bq kg(-1)) are calculated 1 m above ground for photon emitters of natural radionuclides uniformly distributed in the soil. Three Monte Carlo codes are used: 1) The MCNP code of Los Alamos; 2) The GEANT code of CERN; and 3) a Monte Carlo code developed in the Nuclear Technology Laboratory of the Aristotle University of Thessaloniki. The accuracy of the Monte Carlo results is tested by the comparison of the unscattered flux obtained by the three Monte Carlo codes with an independent straightforward calculation. All codes and particularly the MCNP calculate accurately the absorbed dose rate in air due to the unscattered radiation. For the total radiation (unscattered plus scattered) the D(CF) values calculated from the three codes are in very good agreement between them. The comparison between these results and the results deduced previously by other authors indicates a good agreement (less than 15% of difference) for photon energies above 1,500 keV. Antithetically, the agreement is not as good (difference of 20-30%) for the low energy photons. PMID:10688452

  15. Comparison of measured and Monte Carlo calculated dose distributions in inhomogeneous phantoms in clinical electron beams

    NASA Astrophysics Data System (ADS)

    Doucet, R.; Olivares, M.; DeBlois, F.; Podgorsak, E. B.; Kawrakow, I.; Seuntjens, J.

    2003-08-01

    Calculations of dose distributions in heterogeneous phantoms in clinical electron beams, carried out using the fast voxel Monte Carlo (MC) system XVMC and the conventional MC code EGSnrc, were compared with measurements. Irradiations were performed using the 9 MeV and 15 MeV beams from a Varian Clinac-18 accelerator with a 10 × 10 cm2 applicator and an SSD of 100 cm. Depth doses were measured with thermoluminescent dosimetry techniques (TLD 700) in phantoms consisting of slabs of Solid WaterTM (SW) and bone and slabs of SW and lung tissue-equivalent materials. Lateral profiles in water were measured using an electron diode at different depths behind one and two immersed aluminium rods. The accelerator was modelled using the EGS4/BEAM system and optimized phase-space files were used as input to the EGSnrc and the XVMC calculations. Also, for the XVMC, an experiment-based beam model was used. All measurements were corrected by the EGSnrc-calculated stopping power ratios. Overall, there is excellent agreement between the corrected experimental and the two MC dose distributions. Small remaining discrepancies may be due to the non-equivalence between physical and simulated tissue-equivalent materials and to detector fluence perturbation effect correction factors that were calculated for the 9 MeV beam at selected depths in the heterogeneous phantoms.

  16. Calculation of effective dose from measurements of secondary neutron spectra and scattered photon dose from dynamic MLC IMRT for 6 MV, 15 MV, and 18 MV beam energies.

    PubMed

    Howell, Rebecca M; Hertel, Nolan E; Wang, Zhonglu; Hutchinson, Jesson; Fullerton, Gary D

    2006-02-01

    Effective doses were calculated from the delivery of 6 MV, 15 MV, and 18 MV conventional and intensity-modulated radiation therapy (IMRT) prostate treatment plans. ICRP-60 tissue weighting factors were used for the calculations. Photon doses were measured in phantom for all beam energies. Neutron spectra were measured for 15 MV and 18 MV and ICRP-74 quality conversion factors used to calculate ambient dose equivalents. The ambient dose equivalents were corrected for each tissue using neutron depth dose data from the literature. The depth corrected neutron doses were then used as a measure of the neutron component of the ICRP protection quantity, organ equivalent dose. IMRT resulted in an increased photon dose to many organs. However, the IMRT treatments resulted in an overall decrease in effective dose compared to conventional radiotherapy. This decrease correlates to the ability of an intensity-modulated field to minimize dose to critical normal structures in close proximity to the treatment volume. In a comparison of the three beam energies used for the IMRT treatments, 6 MV resulted in the lowest effective dose, while 18 MV resulted in the highest effective dose. This is attributed to the large neutron contribution for 18 MV compared to no neutron contribution for 6 MV. PMID:16532941

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

    PubMed Central

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

    2008-01-01

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

  18. Feasibility of a Multigroup Deterministic Solution Method for Three-Dimensional Radiotherapy Dose Calculations

    SciTech Connect

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

    2008-09-01

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

  19. Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism: Current status and recommendations for clinical implementation

    SciTech Connect

    Beaulieu, Luc; Carlsson Tedgren, Asa; Carrier, Jean-Francois; and others

    2012-10-15

    the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim recommendations are made and potential areas of research are identified. Application of TG-186 guidance should retain practice uniformity in transitioning from the TG-43 to the MBDCA approach.

  20. Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism: current status and recommendations for clinical implementation.

    PubMed

    Beaulieu, Luc; Carlsson Tedgren, Asa; Carrier, Jean-Francois; Davis, Stephen D; Mourtada, Firas; Rivard, Mark J; Thomson, Rowan M; Verhaegen, Frank; Wareing, Todd A; Williamson, Jeffrey F

    2012-10-01

    to the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim recommendations are made and potential areas of research are identified. Application of TG-186 guidance should retain practice uniformity in transitioning from the TG-43 to the MBDCA approach. PMID:23039658

  1. Antikythera Calculator advances modern science of 19 centuries

    NASA Astrophysics Data System (ADS)

    Pastore, Giovanni

    2010-08-01

    The Greek astronomic calculator, discovered in the depth of the sea in a naval wreckage of the 1st century B.C. in front of the island of Antikythera, is the most amazing among the archaeological discoveries of last century. The mechanism immediately appeared like a device out of its time. After years of study this devise is still provoking a discussion between scientists and archaeologists because of the complexity and the modernity of the scientific knowledge the work presupposes. Its epicyclical gearings show the high level of the scientific culture reached in that period of history. The knowledge of the planetary motion, necessary to the design of the epicyclic gearing of the Calculator of Antikythera, presumes that ancient Greek scientists knew the planetary motion of the celestial bodies and had already achieved the same results that have been attributed to scientists 19 centuries later. The scientific value of this gear mechanism is indisputable because the inventor of the Calculator of Antikythera had the knowledge that was "re-discovered" centuries later as the heliocentric theory proposed by Niccolò Copernicus in 1543 ( De revolutionibus orbium coelestium), the universal gravitation law formulated by Isaac Newton in 1687 ( Philosophiae Naturalis Principia Mathematica), and the kinematic study of the epicyclical gearings published by Robert Willis in 1841 ( Principles of mechanism).

  2. An analytic linear accelerator source model for GPU-based Monte Carlo dose calculations.

    PubMed

    Tian, Zhen; Li, Yongbao; Folkerts, Michael; Shi, Feng; Jiang, Steve B; Jia, Xun

    2015-10-21

    Recently, there has been a lot of research interest in developing fast Monte Carlo (MC) dose calculation methods on graphics processing unit (GPU) platforms. A good linear accelerator (linac) source model is critical for both accuracy and efficiency considerations. In principle, an analytical source model should be more preferred for GPU-based MC dose engines than a phase-space file-based model, in that data loading and CPU-GPU data transfer can be avoided. In this paper, we presented an analytical field-independent source model specifically developed for GPU-based MC dose calculations, associated with a GPU-friendly sampling scheme. A key concept called phase-space-ring (PSR) was proposed. Each PSR contained a group of particles that were of the same type, close in energy and reside in a narrow ring on the phase-space plane located just above the upper jaws. The model parameterized the probability densities of particle location, direction and energy for each primary photon PSR, scattered photon PSR and electron PSR. Models of one 2D Gaussian distribution or multiple Gaussian components were employed to represent the particle direction distributions of these PSRs. A method was developed to analyze a reference phase-space file and derive corresponding model parameters. To efficiently use our model in MC dose calculations on GPU, we proposed a GPU-friendly sampling strategy, which ensured that the particles sampled and transported simultaneously are of the same type and close in energy to alleviate GPU thread divergences. To test the accuracy of our model, dose distributions of a set of open fields in a water phantom were calculated using our source model and compared to those calculated using the reference phase-space files. For the high dose gradient regions, the average distance-to-agreement (DTA) was within 1 mm and the maximum DTA within 2 mm. For relatively low dose gradient regions, the root-mean-square (RMS) dose difference was within 1.1% and the maximum

  3. An analytic linear accelerator source model for GPU-based Monte Carlo dose calculations

    NASA Astrophysics Data System (ADS)

    Tian, Zhen; Li, Yongbao; Folkerts, Michael; Shi, Feng; Jiang, Steve B.; Jia, Xun

    2015-10-01

    Recently, there has been a lot of research interest in developing fast Monte Carlo (MC) dose calculation methods on graphics processing unit (GPU) platforms. A good linear accelerator (linac) source model is critical for both accuracy and efficiency considerations. In principle, an analytical source model should be more preferred for GPU-based MC dose engines than a phase-space file-based model, in that data loading and CPU-GPU data transfer can be avoided. In this paper, we presented an analytical field-independent source model specifically developed for GPU-based MC dose calculations, associated with a GPU-friendly sampling scheme. A key concept called phase-space-ring (PSR) was proposed. Each PSR contained a group of particles that were of the same type, close in energy and reside in a narrow ring on the phase-space plane located just above the upper jaws. The model parameterized the probability densities of particle location, direction and energy for each primary photon PSR, scattered photon PSR and electron PSR. Models of one 2D Gaussian distribution or multiple Gaussian components were employed to represent the particle direction distributions of these PSRs. A method was developed to analyze a reference phase-space file and derive corresponding model parameters. To efficiently use our model in MC dose calculations on GPU, we proposed a GPU-friendly sampling strategy, which ensured that the particles sampled and transported simultaneously are of the same type and close in energy to alleviate GPU thread divergences. To test the accuracy of our model, dose distributions of a set of open fields in a water phantom were calculated using our source model and compared to those calculated using the reference phase-space files. For the high dose gradient regions, the average distance-to-agreement (DTA) was within 1 mm and the maximum DTA within 2 mm. For relatively low dose gradient regions, the root-mean-square (RMS) dose difference was within 1.1% and the maximum

  4. SU-F-BRF-11: Dose Rearrangement in High Dose Locally Advanced Lung Patients Based On Perfusion Imaging

    SciTech Connect

    Matrosic, C; Jarema, D; Kong, F; McShan, D; Stenmark, M; Owen, D; Ten Haken, R; Matuszak, M

    2014-06-15

    Purpose: The use of mean lung dose (MLD) limits allows individualization of lung patient tumor doses at safe levels. However, MLD does not account for local lung function differences between patients, leading to toxicity variability at the same MLD. We investigated dose rearrangement to minimize dose to functional lung, as measured by perfusion SPECT, while maintaining target coverage and conventional MLD limits. Methods: Retrospective plans were optimized for 15 locally advanced NSCLC patients enrolled in a prospective imaging trial. A priority-based optimization system was used. The baseline priorities were (1) meet OAR dose constraints, (2) maximize target gEUD, and (3) minimize physical MLD. As a final step, normal tissue doses were minimized. To determine the benefit of rearranging dose using perfusion SPECT, plans were reoptimized to minimize functional lung gEUD as the 4th priority. Results: When only minimizing physical MLD, the functional lung gEUD was 10.8+/−5.0 Gy (4.3–19.8 Gy). Only 3/15 cases showed a decrease in functional lung gEUD of ≥4% when rearranging dose to minimize functional gEUD in the cost function (10.5+/−5.0 Gy range 4.3−19.7). Although OAR constraints were respected, the dose rearrangement resulted in ≥10% increases in gEUD to an OAR in 4/15 cases. Only slight reductions in functional lung gEUD were noted when omitting the minimization of physical MLD, suggesting that constraining the target gEUD minimizes the potential to redistribute dose. Conclusion: Prioritydriven optimization permits the generation of plans that respect traditional OAR limits and target coverage, but with the ability to rearrange dose based on functional imaging. The latter appears to be limited due to the decreased solution space when constraining target coverage. Since dose rearrangement may increase dose to other OARs, it is also worthwhile to investigate global biomarkers of lung toxicity to further individualize treatment in this population

  5. Dose calculation for permanent prostate implants incorporating spatially anisotropic linearly time-resolving edema

    SciTech Connect

    Monajemi, T. T.; Clements, Charles M.; Sloboda, Ron S.

    2011-04-15

    Purpose: The objectives of this study were (i) to develop a dose calculation method for permanent prostate implants that incorporates a clinically motivated model for edema and (ii) to illustrate the use of the method by calculating the preimplant dosimetry error for a reference configuration of {sup 125}I, {sup 103}Pd, and {sup 137}Cs seeds subject to edema-induced motions corresponding to a variety of model parameters. Methods: A model for spatially anisotropic edema that resolves linearly with time was developed based on serial magnetic resonance imaging measurements made previously at our center to characterize the edema for a group of n=40 prostate implant patients [R. S. Sloboda et al., ''Time course of prostatic edema post permanent seed implant determined by magnetic resonance imaging,'' Brachytherapy 9, 354-361 (2010)]. Model parameters consisted of edema magnitude, {Delta}, and period, T. The TG-43 dose calculation formalism for a point source was extended to incorporate the edema model, thus enabling calculation via numerical integration of the cumulative dose around an individual seed in the presence of edema. Using an even power piecewise-continuous polynomial representation for the radial dose function, the cumulative dose was also expressed in closed analytical form. Application of the method was illustrated by calculating the preimplant dosimetry error, RE{sub preplan}, in a 5x5x5 cm{sup 3} volume for {sup 125}I (Oncura 6711), {sup 103}Pd (Theragenics 200), and {sup 131}Cs (IsoRay CS-1) seeds arranged in the Radiological Physics Center test case 2 configuration for a range of edema relative magnitudes ({Delta}=[0.1,0.2,0.4,0.6,1.0]) and periods (T=[28,56,84] d). Results were compared to preimplant dosimetry errors calculated using a variation of the isotropic edema model developed by Chen et al. [''Dosimetric effects of edema in permanent prostate seed implants: A rigorous solution,'' Int. J. Radiat. Oncol., Biol., Phys. 47, 1405-1419 (2000

  6. Automatic commissioning of a GPU-based Monte Carlo radiation dose calculation code for photon radiotherapy

    NASA Astrophysics Data System (ADS)

    Tian, Zhen; Jiang Graves, Yan; Jia, Xun; Jiang, Steve B.

    2014-10-01

    Monte Carlo (MC) simulation is commonly considered as the most accurate method for radiation dose calculations. Commissioning of a beam model in the MC code against a clinical linear accelerator beam is of crucial importance for its clinical implementation. In this paper, we propose an automatic commissioning method for our GPU-based MC dose engine, gDPM. gDPM utilizes a beam model based on a concept of phase-space-let (PSL). A PSL contains a group of particles that are of the same type and close in space and energy. A set of generic PSLs was generated by splitting a reference phase-space file. Each PSL was associated with a weighting factor, and in dose calculations the particle carried a weight corresponding to the PSL where it was from. Dose for each PSL in water was pre-computed, and hence the dose in water for a whole beam under a given set of PSL weighting factors was the weighted sum of the PSL doses. At the commissioning stage, an optimization problem was solved to adjust the PSL weights in order to minimize the difference between the calculated dose and measured one. Symmetry and smoothness regularizations were utilized to uniquely determine the solution. An augmented Lagrangian method was employed to solve the optimization problem. To validate our method, a phase-space file of a Varian TrueBeam 6 MV beam was used to generate the PSLs for 6 MV beams. In a simulation study, we commissioned a Siemens 6 MV beam on which a set of field-dependent phase-space files was available. The dose data of this desired beam for different open fields and a small off-axis open field were obtained by calculating doses using these phase-space files. The 3D γ-index test passing rate within the regions with dose above 10% of dmax dose for those open fields tested was improved averagely from 70.56 to 99.36% for 2%/2 mm criteria and from 32.22 to 89.65% for 1%/1 mm criteria. We also tested our commissioning method on a six-field head-and-neck cancer IMRT plan. The

  7. SU-E-T-416: VMAT Dose Calculations Using Cone Beam CT Images: A Preliminary Study

    SciTech Connect

    Yu, S; Sehgal, V; Kuo, J; Daroui, P; Ramsinghani, N; Al-Ghazi, M

    2014-06-01

    Purpose: Cone beam CT (CBCT) images have been used routinely for patient positioning throughout the treatment course. However, use of CBCT for dose calculation is still investigational. The purpose of this study is to assess the utility of CBCT images for Volumetric Modulated Arc Therapy (VMAT) plan dose calculation. Methods: A CATPHAN 504 phantom (The Phantom Laboratory, Salem, NY) was used to compare the dosimetric and geometric accuracy between conventional CT and CBCT (in both full and half fan modes). Hounsfield units (HU) profiles at different density areas were evaluated. A C shape target that surrounds a central avoidance structure was created and a VMAT plan was generated on the CT images and copied to the CBCT phantom images. Patient studies included three brain patients, and one head and neck (H'N) patient. VMAT plans generated on the patients treatment planning CT was applied to CBCT images obtained during the first treatment. Isodose distributions and dosevolume- histograms (DVHs) were compared. Results: For the phantom study, the HU difference between CT and CBCT is within 100 (maximum 96 HU for Teflon CBCT images in full fan mode). The impact of these differences on the calculated dose distributions was clinically insignificant. In both phantom and patient studies, target DVHs based on CBCT images were in excellent agreement with those based on planning CT images. Mean, Median, near minimum (D98%), and near maximum (D2%) doses agreed within 0-2.5%. A slightly larger discrepancy is observed in the patient studies compared to that seen in the phantom study, (0-1% vs. 0 - 2.5%). Conclusion: CBCT images can be used to accurately predict dosimetric results, without any HU correction. It is feasible to use CBCT to evaluate the actual dose delivered at each fraction. The dosimetric consequences resulting from tumor response and patient geometry changes could be monitored.

  8. Modeling of an industrial environment: external dose calculations based on Monte Carlo simulations of photon transport.

    PubMed

    Kis, Zoltán; Eged, Katalin; Voigt, Gabriele; Meckbach, Reinhard; Müller, Heinz

    2004-02-01

    External gamma exposures from radionuclides deposited on surfaces usually result in the major contribution to the total dose to the public living in urban-industrial environments. The aim of the paper is to give an example for a calculation of the collective and averted collective dose due to the contamination and decontamination of deposition surfaces in a complex environment based on the results of Monte Carlo simulations. The shielding effects of the structures in complex and realistic industrial environments (where productive and/or commercial activity is carried out) were computed by the use of Monte Carlo method. Several types of deposition areas (walls, roofs, windows, streets, lawn) were considered. Moreover, this paper gives a summary about the time dependence of the source strengths relative to a reference surface and a short overview about the mechanical and chemical intervention techniques which can be applied in this area. An exposure scenario was designed based on a survey of average German and Hungarian supermarkets. In the first part of the paper the air kermas per photon per unit area due to each specific deposition area contaminated by 137Cs were determined at several arbitrary locations in the whole environment relative to a reference value of 8.39 x 10(-4) pGy per gamma m(-2). The calculations provide the possibility to assess the whole contribution of a specific deposition area to the collective dose, separately. According to the current results, the roof and the paved area contribute the most part (approximately 92%) to the total dose in the first year taking into account the relative contamination of the deposition areas. When integrating over 10 or 50 y, these two surfaces remain the most important contributors as well but the ratio will increasingly be shifted in favor of the roof. The decontamination of the roof and the paved area results in about 80-90% of the total averted collective dose in each calculated time period (1, 10, 50 y

  9. The calculation of radial dose from heavy ions: predictions of biological action cross sections

    NASA Technical Reports Server (NTRS)

    Katz, R.; Cucinotta, F. A.; Zhang, C. X.; Wilson, J. W. (Principal Investigator)

    1996-01-01

    The track structure model of heavy ion cross sections was developed by Katz and co-workers in the 1960s. In this model the action cross section is evaluated by mapping the dose-response of a detector to gamma rays (modeled from biological target theory) onto the radial dose distribution from delta rays about the path of the ion. This is taken to yield the radial distribution of probability for a "hit" (an interaction leading to an observable end-point). Radial integration of the probability yields the cross section. When different response from ions of different Z having the same stopping power is observed this model may be indicated. Since the 1960s there have been several developments in the computation of the radial dose distribution, in the measurement of these distributions, and in new radiobiological data against which to test the model. The earliest model, by Butts and Katz made use of simplified delta ray distribution functions, of simplified electron range-energy relations, and neglected angular distributions. Nevertheless it made possible the calculation of cross sections for the inactivation of enzymes and viruses, and allowed extension to tracks in nuclear emulsions and other detectors and to biological cells. It set the pattern for models of observable effects in the matter through which the ion passed. Here we outline subsequent calculations of radial dose which make use of improved knowledge of the electron emission spectrum, the electron range-energy relation, the angular distribution, and some considerations of molecular excitation, of particular interest both close to the path of the ion and the outer limits of electron penetration. These are applied to the modeling of action cross sections for the inactivation of several strains of E-coli and B. subtilis spores where extensive measurements in the "thin-down" region have been made with heavy ion beams. Such calculations serve to test the radial dose calculations at the outer limit of electron

  10. GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources

    NASA Astrophysics Data System (ADS)

    Townson, Reid W.; Jia, Xun; Tian, Zhen; Jiang Graves, Yan; Zavgorodni, Sergei; Jiang, Steve B.

    2013-06-01

    A novel phase-space source implementation has been designed for graphics processing unit (GPU)-based Monte Carlo dose calculation engines. Short of full simulation of the linac head, using a phase-space source is the most accurate method to model a clinical radiation beam in dose calculations. However, in GPU-based Monte Carlo dose calculations where the computation efficiency is very high, the time required to read and process a large phase-space file becomes comparable to the particle transport time. Moreover, due to the parallelized nature of GPU hardware, it is essential to simultaneously transport particles of the same type and similar energies but separated spatially to yield a high efficiency. We present three methods for phase-space implementation that have been integrated into the most recent version of the GPU-based Monte Carlo radiotherapy dose calculation package gDPM v3.0. The first method is to sequentially read particles from a patient-dependent phase-space and sort them on-the-fly based on particle type and energy. The second method supplements this with a simple secondary collimator model and fluence map implementation so that patient-independent phase-space sources can be used. Finally, as the third method (called the phase-space-let, or PSL, method) we introduce a novel source implementation utilizing pre-processed patient-independent phase-spaces that are sorted by particle type, energy and position. Position bins located outside a rectangular region of interest enclosing the treatment field are ignored, substantially decreasing simulation time with little effect on the final dose distribution. The three methods were validated in absolute dose against BEAMnrc/DOSXYZnrc and compared using gamma-index tests (2%/2 mm above the 10% isodose). It was found that the PSL method has the optimal balance between accuracy and efficiency and thus is used as the default method in gDPM v3.0. Using the PSL method, open fields of 4 × 4, 10 × 10 and 30 × 30 cm

  11. GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources.

    PubMed

    Townson, Reid W; Jia, Xun; Tian, Zhen; Graves, Yan Jiang; Zavgorodni, Sergei; Jiang, Steve B

    2013-06-21

    A novel phase-space source implementation has been designed for graphics processing unit (GPU)-based Monte Carlo dose calculation engines. Short of full simulation of the linac head, using a phase-space source is the most accurate method to model a clinical radiation beam in dose calculations. However, in GPU-based Monte Carlo dose calculations where the computation efficiency is very high, the time required to read and process a large phase-space file becomes comparable to the particle transport time. Moreover, due to the parallelized nature of GPU hardware, it is essential to simultaneously transport particles of the same type and similar energies but separated spatially to yield a high efficiency. We present three methods for phase-space implementation that have been integrated into the most recent version of the GPU-based Monte Carlo radiotherapy dose calculation package gDPM v3.0. The first method is to sequentially read particles from a patient-dependent phase-space and sort them on-the-fly based on particle type and energy. The second method supplements this with a simple secondary collimator model and fluence map implementation so that patient-independent phase-space sources can be used. Finally, as the third method (called the phase-space-let, or PSL, method) we introduce a novel source implementation utilizing pre-processed patient-independent phase-spaces that are sorted by particle type, energy and position. Position bins located outside a rectangular region of interest enclosing the treatment field are ignored, substantially decreasing simulation time with little effect on the final dose distribution. The three methods were validated in absolute dose against BEAMnrc/DOSXYZnrc and compared using gamma-index tests (2%/2 mm above the 10% isodose). It was found that the PSL method has the optimal balance between accuracy and efficiency and thus is used as the default method in gDPM v3.0. Using the PSL method, open fields of 4 × 4, 10 × 10 and 30 × 30 cm

  12. Heavy ion track-structure calculations for radial dose in arbitrary materials

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Katz, Robert; Wilson, John W.; Dubey, Rajendra R.

    1995-01-01

    The delta-ray theory of track structure is compared with experimental data for the radial dose from heavy ion irradiation. The effects of electron transmission and the angular dependence of secondary electron ejection are included in the calculations. Several empirical formulas for electron range and energy are compared in a wide variety of materials in order to extend the application of the track-structure theory. The model of Rudd for the secondary electron-spectrum in proton collisions, which is based on a modified classical kinematics binary encounter model at high energies and a molecular promotion model at low energies, is employed. For heavier projectiles, the secondary electron spectrum is found by scaling the effective charge. Radial dose calculations for carbon, water, silicon, and gold are discussed. The theoretical data agreed well with the experimental data.

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

    PubMed

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

    2009-03-01

    The methods used to calculate radiological and toxicological doses to hypothetical persons inside either a U.S. Army Abrams tank or Bradley Fighting Vehicle that has been perforated by depleted uranium munitions are described. Data from time- and particle-size-resolved measurements of depleted uranium aerosol as well as particle-size-resolved measurements of aerosol solubility in lung fluids for aerosol produced in the breathing zones of the hypothetical occupants were used. The aerosol was approximated as a mixture of nine monodisperse (single particle size) components corresponding to particle size increments measured by the eight stages plus the backup filter of the cascade impactors used. A Markov Chain Monte Carlo Bayesian analysis technique was employed, which straightforwardly calculates the uncertainties in doses. Extensive quality control checking of the various computer codes used is described. PMID:19204488

  14. Calculation of conversion factors for effective dose for various interventional radiology procedures

    SciTech Connect

    Compagnone, Gaetano; Giampalma, Emanuela; Domenichelli, Sara; Renzulli, Matteo; Golfieri, Rita

    2012-05-15

    Purpose: To provide dose-area-product (DAP) to effective dose (E) conversion factors for complete interventional procedures, based on in-the-field clinical measurements of DAP values and using tabulated E/DAP conversion factors for single projections available from the literature. Methods: Nine types of interventional procedures were performed on 84 patients with two angiographic systems. Different calibration curves (with and without patient table attenuation) were calculated for each DAP meter. Clinical and dosimetric parameters were recorded in-the-field for each projection and for all patients, and a conversion factor linking DAP and effective doses was derived for each complete procedure making use of published, Monte Carlo calculated conversion factors for single static projections. Results: Fluoroscopy time and DAP values for the lowest-dose procedure (biliary drainage) were approximately 3-fold and 13-fold lower, respectively, than those for the highest-dose examination (transjugular intrahepatic portosystemic shunt, TIPS). Median E/DAP conversion factors from 0.12 (abdominal percutaneous transluminal angioplasty) to 0.25 (Nephrostomy) mSvGy{sup -1} cm{sup -2} were obtained and good correlations between E and DAP were found for all procedures, with R{sup 2} coefficients ranging from 0.80 (abdominal angiography) to 0.99 (biliary stent insertion, Nephrostomy and TIPS). The DAP values obtained in this study showed general consistency with the values provided in the literature and median E values ranged from 4.0 mSv (biliary drainage) to 49.6 mSv (TIPS). Conclusions: Values of E/DAP conversion factors were derived for each procedure from a comprehensive analysis of projection and dosimetric data: they could provide a good evaluation for the stochastic effects. These results can be obtained by means of a close cooperation between different interventional professionals involved in patient care and dose optimization.

  15. Calculations of increased solar UV fluxes and DUV doses due to stratospheric-ozone depletions

    SciTech Connect

    Zardecki, A.; Gerstl, S.A.W.

    1982-02-01

    Accurate radiative transfer calculations are performed in the middle ultraviolet spectral region for aerosol-loaded atmospheres with the goal of determining the solar irradiance at the ground and quantifying the irradiance perturbations due to the presence of aerosols and various ozone depletions. The extent of the increase of UV-B radiation as a function of wave-length and solar zenith angle is calculated for five model atmospheres. In addition, the damaging ultraviolet dose rates and radiation amplification factors are evaluated at different latitudes and seasons for erythemal and DNA action spectra.

  16. Monte Carlo calculations of lung dose in ORNL phantom for boron neutron capture therapy.

    PubMed

    Krstic, D; Markovic, V M; Jovanovic, Z; Milenkovic, B; Nikezic, D; Atanackovic, J

    2014-10-01

    Monte Carlo simulations were performed to evaluate dose for possible treatment of cancers by boron neutron capture therapy (BNCT). The computational model of male Oak Ridge National Laboratory (ORNL) phantom was used to simulate tumours in the lung. Calculations have been performed by means of the MCNP5/X code. In this simulation, two opposite neutron beams were considered, in order to obtain uniform neutron flux distribution inside the lung. The obtained results indicate that the lung cancer could be treated by BNCT under the assumptions of calculations. PMID:24435912

  17. Monte Carlo dose calculations for radiotherapy machines: Theratron 780-C teletherapy case study

    NASA Astrophysics Data System (ADS)

    Teimouri Sichani, B.; Sohrabpour, M.

    2004-03-01

    The Monte Carlo transport code MCNP was used to simulate the photon beam from a Theratronics 780-C cobalt therapy unit and to calculate some dose-dependent parameters as functions of field size. The simulation process has included the source capsule, collimators (fixed and adjustable), lead in the unit head, and the field sizes as ranged from 5 × 5 to 35 × 35 cm2. Calculations have been carried out in a water phantom at a fixed source-surface distance of 80 cm. Detailed simulation of the major components of the therapy unit made it possible to calculate the effects of each unit component on the photon spectrum at the phantom surface. Percentage depth dose and peak scatter factor were evaluated for various field sizes. And tissue-air ratios were also determined for a field size of 10 ×10 cm2, as a function of depth down to 30 cm. To test the accuracy of the calculated results, they were compared with the published data of the British Journal of Radiology (BJR) suppl. 25 and good agreement between measurements and calculations has been obtained. Deviations typically were found to be of the order of 1%.

  18. Advancing QCD-based calculations of energy loss

    NASA Astrophysics Data System (ADS)

    Tywoniuk, Konrad

    2013-08-01

    We give a brief overview of the basics and current developments of QCD-based calculations of radiative processes in medium. We put an emphasis on the underlying physics concepts and discuss the theoretical uncertainties inherently associated with the fundamental parameters to be extracted from data. An important area of development is the study of the single-gluon emission in medium. Moreover, establishing the correct physical picture of multi-gluon emissions is imperative for comparison with data. We will report on progress made in both directions and discuss perspectives for the future.

  19. Foundation of an analytical proton beamlet model for inclusion in a general proton dose calculation system

    NASA Astrophysics Data System (ADS)

    Ulmer, W.; Schaffner, B.

    2011-03-01

    We have developed a model for proton depth dose and lateral distributions based on Monte Carlo calculations (GEANT4) and an integration procedure of Bethe-Bloch equation (BBE). The model accounts for the transport of primary and secondary protons, the creation of recoil protons and heavy recoil nuclei as well as lateral scattering of these contributions. The buildup, which is experimentally observed in higher energy depth dose curves, is modeled by an inclusion of two different origins: (1) secondary reaction protons with a contribution of ca. 65% of the buildup (for monoenergetic protons). (2) Landau tails as well as Gaussian type of fluctuations for range straggling effects. All parameters of the model for initially monoenergetic proton beams have been obtained from Monte Carlo calculations or checked by them. Furthermore, there are a few parameters, which can be obtained by fitting the model to the measured depth dose curves in order to describe individual characteristics of the beamline—the most important being the initial energy spread. We find that the free parameters of the depth dose model can be predicted for any intermediate energy from a couple of measured curves.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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× 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× and 1.95× 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.

  1. An image-guidance system for dynamic dose calculation in prostate brachytherapy using ultrasound and fluoroscopy

    PubMed Central

    Kuo, Nathanael; Dehghan, Ehsan; Deguet, Anton; Mian, Omar Y.; Le, Yi; Burdette, E. Clif; Fichtinger, Gabor; Prince, Jerry L.; Song, Danny Y.; Lee, Junghoon

    2014-01-01

    Purpose: Brachytherapy is a standard option of care for prostate cancer patients but may be improved by dynamic dose calculation based on localized seed positions. The American Brachytherapy Society states that the major current limitation of intraoperative treatment planning is the inability to localize the seeds in relation to the prostate. An image-guidance system was therefore developed to localize seeds for dynamic dose calculation. Methods: The proposed system is based on transrectal ultrasound (TRUS) and mobile C-arm fluoroscopy, while using a simple fiducial with seed-like markers to compute pose from the nonencoded C-arm. Three or more fluoroscopic images and an ultrasound volume are acquired and processed by a pipeline of algorithms: (1) seed segmentation, (2) fiducial detection with pose estimation, (3) seed matching with reconstruction, and (4) fluoroscopy-to-TRUS registration. Results: The system was evaluated on ten phantom cases, resulting in an overall mean error of 1.3 mm. The system was also tested on 37 patients and each algorithm was evaluated. Seed segmentation resulted in a 1% false negative rate and 2% false positive rate. Fiducial detection with pose estimation resulted in a 98% detection rate. Seed matching with reconstruction had a mean error of 0.4 mm. Fluoroscopy-to-TRUS registration had a mean error of 1.3 mm. Moreover, a comparison of dose calculations between the authors’ intraoperative method and an independent postoperative method shows a small difference of 7% and 2% forD90 and V100, respectively. Finally, the system demonstrated the ability to detect cold spots and required a total processing time of approximately 1 min. Conclusions: The proposed image-guidance system is the first practical approach to dynamic dose calculation, outperforming earlier solutions in terms of robustness, ease of use, and functional completeness. PMID:25186387

  2. An image-guidance system for dynamic dose calculation in prostate brachytherapy using ultrasound and fluoroscopy

    SciTech Connect

    Kuo, Nathanael Prince, Jerry L.; Dehghan, Ehsan; Deguet, Anton; Mian, Omar Y.; Le, Yi; Song, Danny Y.; Burdette, E. Clif; Fichtinger, Gabor; Lee, Junghoon

    2014-09-15

    Purpose: Brachytherapy is a standard option of care for prostate cancer patients but may be improved by dynamic dose calculation based on localized seed positions. The American Brachytherapy Society states that the major current limitation of intraoperative treatment planning is the inability to localize the seeds in relation to the prostate. An image-guidance system was therefore developed to localize seeds for dynamic dose calculation. Methods: The proposed system is based on transrectal ultrasound (TRUS) and mobile C-arm fluoroscopy, while using a simple fiducial with seed-like markers to compute pose from the nonencoded C-arm. Three or more fluoroscopic images and an ultrasound volume are acquired and processed by a pipeline of algorithms: (1) seed segmentation, (2) fiducial detection with pose estimation, (3) seed matching with reconstruction, and (4) fluoroscopy-to-TRUS registration. Results: The system was evaluated on ten phantom cases, resulting in an overall mean error of 1.3 mm. The system was also tested on 37 patients and each algorithm was evaluated. Seed segmentation resulted in a 1% false negative rate and 2% false positive rate. Fiducial detection with pose estimation resulted in a 98% detection rate. Seed matching with reconstruction had a mean error of 0.4 mm. Fluoroscopy-to-TRUS registration had a mean error of 1.3 mm. Moreover, a comparison of dose calculations between the authors’ intraoperative method and an independent postoperative method shows a small difference of 7% and 2% forD{sub 90} and V{sub 100}, respectively. Finally, the system demonstrated the ability to detect cold spots and required a total processing time of approximately 1 min. Conclusions: The proposed image-guidance system is the first practical approach to dynamic dose calculation, outperforming earlier solutions in terms of robustness, ease of use, and functional completeness.

  3. Final Aperture Superposition Technique applied to fast calculation of electron output factors and depth dose curves

    SciTech Connect

    Faddegon, B.A.; Villarreal-Barajas, J.E.

    2005-11-15

    The Final Aperture Superposition Technique (FAST) is described and applied to accurate, near instantaneous calculation of the relative output factor (ROF) and central axis percentage depth dose curve (PDD) for clinical electron beams used in radiotherapy. FAST is based on precalculation of dose at select points for the two extreme situations of a fully open final aperture and a final aperture with no opening (fully shielded). This technique is different than conventional superposition of dose deposition kernels: The precalculated dose is differential in position of the electron or photon at the downstream surface of the insert. The calculation for a particular aperture (x-ray jaws or MLC, insert in electron applicator) is done with superposition of the precalculated dose data, using the open field data over the open part of the aperture and the fully shielded data over the remainder. The calculation takes explicit account of all interactions in the shielded region of the aperture except the collimator effect: Particles that pass from the open part into the shielded part, or visa versa. For the clinical demonstration, FAST was compared to full Monte Carlo simulation of 10x10,2.5x2.5, and 2x8 cm{sup 2} inserts. Dose was calculated to 0.5% precision in 0.4x0.4x0.2 cm{sup 3} voxels, spaced at 0.2 cm depth intervals along the central axis, using detailed Monte Carlo simulation of the treatment head of a commercial linear accelerator for six different electron beams with energies of 6-21 MeV. Each simulation took several hours on a personal computer with a 1.7 Mhz processor. The calculation for the individual inserts, done with superposition, was completed in under a second on the same PC. Since simulations for the pre calculation are only performed once, higher precision and resolution can be obtained without increasing the calculation time for individual inserts. Fully shielded contributions were largest for small fields and high beam energy, at the surface, reaching a

  4. Evaluation of on-board kV cone beam CT (CBCT)-based dose calculation

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Schreibmann, Eduard; Li, Tianfang; Wang, Chuang; Xing, Lei

    2007-02-01

    On-board CBCT images are used to generate patient geometric models to assist patient setup. The image data can also, potentially, be used for dose reconstruction in combination with the fluence maps from treatment plan. Here we evaluate the achievable accuracy in using a kV CBCT for dose calculation. Relative electron density as a function of HU was obtained for both planning CT (pCT) and CBCT using a Catphan-600 calibration phantom. The CBCT calibration stability was monitored weekly for 8 consecutive weeks. A clinical treatment planning system was employed for pCT- and CBCT-based dose calculations and subsequent comparisons. Phantom and patient studies were carried out. In the former study, both Catphan-600 and pelvic phantoms were employed to evaluate the dosimetric performance of the full-fan and half-fan scanning modes. To evaluate the dosimetric influence of motion artefacts commonly seen in CBCT images, the Catphan-600 phantom was scanned with and without cyclic motion using the pCT and CBCT scanners. The doses computed based on the four sets of CT images (pCT and CBCT with/without motion) were compared quantitatively. The patient studies included a lung case and three prostate cases. The lung case was employed to further assess the adverse effect of intra-scan organ motion. Unlike the phantom study, the pCT of a patient is generally acquired at the time of simulation and the anatomy may be different from that of CBCT acquired at the time of treatment delivery because of organ deformation. To tackle the problem, we introduced a set of modified CBCT images (mCBCT) for each patient, which possesses the geometric information of the CBCT but the electronic density distribution mapped from the pCT with the help of a BSpline deformable image registration software. In the patient study, the dose computed with the mCBCT was used as a surrogate of the 'ground truth'. We found that the CBCT electron density calibration curve differs moderately from that of pCT. No

  5. Modelling of electron contamination in clinical photon beams for Monte Carlo dose calculation

    NASA Astrophysics Data System (ADS)

    Yang, J.; Li, J. S.; Qin, L.; Xiong, W.; Ma, C.-M.

    2004-06-01

    The purpose of this work is to model electron contamination in clinical photon beams and to commission the source model using measured data for Monte Carlo treatment planning. In this work, a planar source is used to represent the contaminant electrons at a plane above the upper jaws. The source size depends on the dimensions of the field size at the isocentre. The energy spectra of the contaminant electrons are predetermined using Monte Carlo simulations for photon beams from different clinical accelerators. A 'random creep' method is employed to derive the weight of the electron contamination source by matching Monte Carlo calculated monoenergetic photon and electron percent depth-dose (PDD) curves with measured PDD curves. We have integrated this electron contamination source into a previously developed multiple source model and validated the model for photon beams from Siemens PRIMUS accelerators. The EGS4 based Monte Carlo user code BEAM and MCSIM were used for linac head simulation and dose calculation. The Monte Carlo calculated dose distributions were compared with measured data. Our results showed good agreement (less than 2% or 2 mm) for 6, 10 and 18 MV photon beams.

  6. Optimised geometry to calculate dose rate conversion coefficient for external exposure to photons.

    PubMed

    Askri, B; Manai, K; Trabelsi, A; Baccari, B

    2008-01-01

    A single-parameter geometry to describe soil is achieved for Monte Carlo calculation of absorbed dose rate in air for photon emitters from natural radionuclides. This optimised geometry based on physical assumptions consists of the soil part whose emitted radiation has a given minimum probability to reach the detector. This geometry was implemented in Geant4 toolkit and a significant reduction in computation time was achieved. Simulation tests have shown that for soil represented by a cylinder of 40 m radius and 1 m deep, >98% of the calculated dose rate conversion coefficients in air at 1 m above the ground is generated by only 6% of the soil volume in the case of uniform distribution of radioactivity, and >99.2% of the calculated dose rate for an exponential distribution. When the soil is represented by the entire optimised geometry, 99% of the conversion coefficients values are reached for a soil depth of 1 m and 100% for that of approximately 2 m. PMID:17959610

  7. SU-F-19A-10: Recalculation and Reporting Clinical HDR 192-Ir Head and Neck Dose Distributions Using Model Based Dose Calculation

    SciTech Connect

    Carlsson Tedgren, A; Persson, M; Nilsson, J

    2014-06-15

    Purpose: To retrospectively re-calculate dose distributions for selected head and neck cancer patients, earlier treated with HDR 192Ir brachytherapy, using Monte Carlo (MC) simulations and compare results to distributions from the planning system derived using TG43 formalism. To study differences between dose to medium (as obtained with the MC code) and dose to water in medium as obtained through (1) ratios of stopping powers and (2) ratios of mass energy absorption coefficients between water and medium. Methods: The MC code Algebra was used to calculate dose distributions according to earlier actual treatment plans using anonymized plan data and CT images in DICOM format. Ratios of stopping power and mass energy absorption coefficients for water with various media obtained from 192-Ir spectra were used in toggling between dose to water and dose to media. Results: Differences between initial planned TG43 dose distributions and the doses to media calculated by MC are insignificant in the target volume. Differences are moderate (within 4–5 % at distances of 3–4 cm) but increase with distance and are most notable in bone and at the patient surface. Differences between dose to water and dose to medium are within 1-2% when using mass energy absorption coefficients to toggle between the two quantities but increase to above 10% for bone using stopping power ratios. Conclusion: MC predicts target doses for head and neck cancer patients in close agreement with TG43. MC yields improved dose estimations outside the target where a larger fraction of dose is from scattered photons. It is important with awareness and a clear reporting of absorbed dose values in using model based algorithms. Differences in bone media can exceed 10% depending on how dose to water in medium is defined.

  8. Modeling a superficial radiotherapy X-ray source for relative dose calculations.

    PubMed

    Johnstone, Christopher D; LaFontaine, Richard; Poirier, Yannick; Tambasco, Mauro

    2015-01-01

    The purpose of this study was to empirically characterize and validate a kilovoltage (kV) X-ray beam source model of a superficial X-ray unit for relative dose calculations in water and assess the accuracy of the British Journal of Radiology Supplement 25 (BJR 25) percentage depth dose (PDD) data. We measured central axis PDDs and dose profiles using an Xstrahl 150 X-ray system. We also compared the measured and calculated PDDs to those in the BJR 25. The Xstrahl source was modeled as an effective point source with varying spatial fluence and spectra. In-air ionization chamber measurements were made along the x- and y-axes of the X-ray beam to derive the spatial fluence and half-value layer (HVL) measurements were made to derive the spatially varying spectra. This beam characterization and resulting source model was used as input for our in-house dose calculation software (kVDoseCalc) to compute radiation dose at points of interest (POIs). The PDDs and dose profiles were measured using 2, 5, and 15 cm cone sizes at 80, 120, 140, and 150 kVp energies in a scanning water phantom using IBA Farmer-type ionization chambers of volumes 0.65 and 0.13 cc, respectively. The percent difference in the computed PDDs compared with our measurements range from -4.8% to 4.8%, with an overall mean percent difference and standard deviation of 1.5% and 0.7%, respectively. The percent difference between our PDD measurements and those from BJR 25 range from -14.0% to 15.7%, with an overall mean percent difference and standard deviation of 4.9% and 2.1%, respectively - showing that the measurements are in much better agreement with kVDoseCalc than BJR 25. The range in percent difference between kVDoseCalc and measurement for profiles was -5.9% to 5.9%, with an overall mean percent difference and standard deviation of 1.4% and 1.4%, respectively. The results demonstrate that our empirically based X-ray source modeling approach for superficial X-ray therapy can be used to accurately

  9. MILDOS - A Computer Program for Calculating Environmental Radiation Doses from Uranium Recovery Operations

    SciTech Connect

    Strange, D. L.; Bander, T. J.

    1981-04-01

    The MILDOS Computer Code estimates impacts from radioactive emissions from uranium milling facilities. These impacts are presented as dose commitments to individuals and the regional population within an 80 km radius of the facility. Only airborne releases of radioactive materials are considered: releases to surface water and to groundwater are not addressed in MILDOS. This code is multi-purposed and can be used to evaluate population doses for NEPA assessments, maximum individual doses for predictive 40 CFR 190 compliance evaluations, or maximum offsite air concentrations for predictive evaluations of 10 CFR 20 compliance. Emissions of radioactive materials from fixed point source locations and from area sources are modeled using a sector-averaged Gaussian plume dispersion model, which utilizes user-provided wind frequency data. Mechanisms such as deposition of particulates, resuspension. radioactive decay and ingrowth of daughter radionuclides are included in the transport model. Annual average air concentrations are computed, from which subsequent impacts to humans through various pathways are computed. Ground surface concentrations are estimated from deposition buildup and ingrowth of radioactive daughters. The surface concentrations are modified by radioactive decay, weathering and other environmental processes. The MILDOS Computer Code allows the user to vary the emission sources as a step function of time by adjustinq the emission rates. which includes shutting them off completely. Thus the results of a computer run can be made to reflect changing processes throughout the facility's operational lifetime. The pathways considered for individual dose commitments and for population impacts are: • Inhalation • External exposure from ground concentrations • External exposure from cloud immersion • Ingestioo of vegetables • Ingestion of meat • Ingestion of milk • Dose commitments are calculated using dose conversion factors, which are ultimately based

  10. SU-F-19A-01: APBI Brachytherapy Treatment Planning: The Impact of Heterogeneous Dose Calculations

    SciTech Connect

    Loupot, S; Han, T; Salehpour, M; Gifford, K

    2014-06-15

    Purpose: To quantify the difference in dose to PTV-EVAL and OARs (skin and rib) as calculated by (TG43) and heterogeneous calculations (CCC). Methods: 25 patient plans (5 Contura and 20 SAVI) were selected for analysis. Clinical dose distributions were computed with a commercially available treatment planning algorithm (TG43-D-(w,w)) and then recomputed with a pre-clinical collapsed cone convolution algorithm (CCCD-( m,m)). PTV-EVAL coverage (V90%, V95%), and rib and skin maximum dose were compared via percent difference. Differences in dose to normal tissue (V150cc, V200cc of PTV-EVAL) were also compared. Changes in coverage and maximum dose to organs at risk are reported in percent change, (100*(TG43 − CCC) / TG43)), and changes in maximum dose to normal tissue are absolute change in cc (TG43 − CCC). Results: Mean differences in V90, V95, V150, and V200 for the SAVI cases were −0.2%, −0.4%, −0.03cc, and −0.14cc, respectively, with maximum differences of −0.78%, −1.7%, 1.28cc, and 1.01cc, respectively. Mean differences in the 0.1cc dose to the rib and skin were −1.4% and −0.22%, respectively, with maximum differences of −4.5% and 16%, respectively. Mean differences in V90, V95, V150, and V200 for the Contura cases were −1.2%, −2.1%, −1.8cc, and −0.59cc, respectively, with maximum differences of −2.0%, −3.16%, −2.9cc, and −0.76cc, respectively. Mean differences in the 0.1cc dose to the rib and skin were −2.6% and −3.9%, respectively, with maximum differences of −3.2% and −5.7%, respectively. Conclusion: The effects of translating clinical knowledge based on D-(w,w) to plans reported in D-(m,m) are minimal (2% or less) on average, but vary based on the type and placement of the device, source, and heterogeneity information.

  11. Dual-energy CT-based material extraction for tissue segmentation in Monte Carlo dose calculations

    NASA Astrophysics Data System (ADS)

    Bazalova, Magdalena; Carrier, Jean-François; Beaulieu, Luc; Verhaegen, Frank

    2008-05-01

    Monte Carlo (MC) dose calculations are performed on patient geometries derived from computed tomography (CT) images. For most available MC codes, the Hounsfield units (HU) in each voxel of a CT image have to be converted into mass density (ρ) and material type. This is typically done with a (HU; ρ) calibration curve which may lead to mis-assignment of media. In this work, an improved material segmentation using dual-energy CT-based material extraction is presented. For this purpose, the differences in extracted effective atomic numbers Z and the relative electron densities ρe of each voxel are used. Dual-energy CT material extraction based on parametrization of the linear attenuation coefficient for 17 tissue-equivalent inserts inside a solid water phantom was done. Scans of the phantom were acquired at 100 kVp and 140 kVp from which Z and ρe values of each insert were derived. The mean errors on Z and ρe extraction were 2.8% and 1.8%, respectively. Phantom dose calculations were performed for 250 kVp and 18 MV photon beams and an 18 MeV electron beam in the EGSnrc/DOSXYZnrc code. Two material assignments were used: the conventional (HU; ρ) and the novel (HU; ρ, Z) dual-energy CT tissue segmentation. The dose calculation errors using the conventional tissue segmentation were as high as 17% in a mis-assigned soft bone tissue-equivalent material for the 250 kVp photon beam. Similarly, the errors for the 18 MeV electron beam and the 18 MV photon beam were up to 6% and 3% in some mis-assigned media. The assignment of all tissue-equivalent inserts was accurate using the novel dual-energy CT material assignment. As a result, the dose calculation errors were below 1% in all beam arrangements. Comparable improvement in dose calculation accuracy is expected for human tissues. The dual-energy tissue segmentation offers a significantly higher accuracy compared to the conventional single-energy segmentation.

  12. Derivation of Geometry Factors for Internal Gamma Dose Calculations for a Cylindrical Radioactive Waste Package

    SciTech Connect

    Lewis, Brent J.; Husain, Aamir

    2002-12-15

    A general methodology was developed to estimate geometry factors for internal gamma dose rate calculations within a cylindrical radioactive waste container. In particular, an average geometry factor is needed to calculate the average energy deposition rate within the container for determination of the internal gas generation rate. Such a calculation is required in order to assess the potential for radioactive waste packages to radiolytically generate combustible gases.This work therefore provides a method for estimating the point and average geometry factors for internal dose assessment for a cylindrical geometry. This analysis is compared to other results where it is shown that the classical work of Hine and Brownell do not correspond to the average geometry factors for a cylindrical body but rather to values at the center of its top or bottom end. The current treatment was further developed into a prototype computer code (PC-CAGE) that calculates the geometry factors numerically for a cylindrical body of any size and material, accounting both for gamma absorption and buildup effects.

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

    PubMed

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

    2012-08-01

    Estimating uncertainties on doses from bioassay data is of interest in epidemiology studies that estimate cancer risk from occupational exposures to radionuclides. Bayesian methods provide a logical framework to calculate these uncertainties. However, occupational exposures often consist of many intakes, and this can make the Bayesian calculation computationally intractable. This paper describes a novel strategy for increasing the computational speed of the calculation by simplifying the intake pattern to a single composite intake, termed as complex intake regime (CIR). In order to assess whether this approximation is accurate and fast enough for practical purposes, the method is implemented by the Weighted Likelihood Monte Carlo Sampling (WeLMoS) method and evaluated by comparing its performance with a Markov Chain Monte Carlo (MCMC) method. The MCMC method gives the full solution (all intakes are independent), but is very computationally intensive to apply routinely. Posterior distributions of model parameter values, intakes and doses are calculated for a representative sample of plutonium workers from the United Kingdom Atomic Energy cohort using the WeLMoS method with the CIR and the MCMC method. The distributions are in good agreement: posterior means and Q(0.025) and Q(0.975) quantiles are typically within 20 %. Furthermore, the WeLMoS method using the CIR converges quickly: a typical case history takes around 10-20 min on a fast workstation, whereas the MCMC method took around 12-72 hr. The advantages and disadvantages of the method are discussed. PMID:22355169

  14. The development of early pediatric models and their application to radiation absorbed dose calculations

    SciTech Connect

    Poston, J.W.

    1989-01-01

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The pediatric'' models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing individual'' pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed.

  15. The development of early pediatric models and their application to radiation absorbed dose calculations

    SciTech Connect

    Poston, J.W.

    1989-12-31

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The ``pediatric`` models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing ``individual`` pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed.

  16. Calculation of External Gamma-Ray and Beta-Ray Doses from Accidental Atmospheric Releases of Radionuclides.

    1981-02-25

    SUBDOSA-II calculates submersion doses from an acute release of radionuclides to the atmosphere, as did SUBDOSA. Doses are calculated as a function of distance from release point, atmospheric stability, and wind speed for a specified radionuclide inventory. Contributions from both beta and gamma radiation are included as a function of tissue depth.

  17. Experimental pencil beam kernels derivation for 3D dose calculation in flattening filter free modulated fields.

    PubMed

    Azcona, Juan Diego; Barbés, Benigno; Wang, Lilie; Burguete, Javier

    2016-01-01

    This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in modulated fields. In our previous work a formalism was developed for ideal flat fluences exiting the linac's head. That framework could not deal with spatially varying energy fluences, so any deviation from the ideal flat fluence was treated as a perturbation. The present work addresses the necessity of implementing an exact analysis where any spatially varying fluence can be used such as those encountered in FFF beams. A major improvement introduced here is to handle the actual fluence in the deconvolution procedure. We studied the uncertainties associated to the kernel derivation with this method. Several Kodak EDR2 radiographic films were irradiated with a 10 MV FFF photon beam from two linacs from different vendors, at the depths of 5, 10, 15, and 20cm in polystyrene (RW3 water-equivalent phantom, PTW Freiburg, Germany). The irradiation field was a 50mm diameter circular field, collimated with a lead block. The 3D kernel for a FFF beam was obtained by deconvolution using the Hankel transform. A correction on the low dose part of the kernel was performed to reproduce accurately the experimental output factors. Error uncertainty in the kernel derivation procedure was estimated to be within 0.2%. Eighteen modulated fields used clinically in different treatment localizations were irradiated at four measurement depths (total of fifty-four film measurements). Comparison through the gamma-index to their corresponding calculated absolute dose distributions showed a number of passing points (3%, 3mm) mostly above 99%. This new procedure is more reliable and robust than the previous one. Its ability to perform accurate independent dose calculations was

  18. Experimental pencil beam kernels derivation for 3D dose calculation in flattening filter free modulated fields

    NASA Astrophysics Data System (ADS)

    Diego Azcona, Juan; Barbés, Benigno; Wang, Lilie; Burguete, Javier

    2016-01-01

    This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in modulated fields. In our previous work a formalism was developed for ideal flat fluences exiting the linac’s head. That framework could not deal with spatially varying energy fluences, so any deviation from the ideal flat fluence was treated as a perturbation. The present work addresses the necessity of implementing an exact analysis where any spatially varying fluence can be used such as those encountered in FFF beams. A major improvement introduced here is to handle the actual fluence in the deconvolution procedure. We studied the uncertainties associated to the kernel derivation with this method. Several Kodak EDR2 radiographic films were irradiated with a 10 MV FFF photon beam from two linacs from different vendors, at the depths of 5, 10, 15, and 20cm in polystyrene (RW3 water-equivalent phantom, PTW Freiburg, Germany). The irradiation field was a 50mm diameter circular field, collimated with a lead block. The 3D kernel for a FFF beam was obtained by deconvolution using the Hankel transform. A correction on the low dose part of the kernel was performed to reproduce accurately the experimental output factors. Error uncertainty in the kernel derivation procedure was estimated to be within 0.2%. Eighteen modulated fields used clinically in different treatment localizations were irradiated at four measurement depths (total of fifty-four film measurements). Comparison through the gamma-index to their corresponding calculated absolute dose distributions showed a number of passing points (3%, 3mm) mostly above 99%. This new procedure is more reliable and robust than the previous one. Its ability to perform accurate independent dose calculations was

  19. Advances in metered dose inhaler technology: formulation development.

    PubMed

    Myrdal, Paul B; Sheth, Poonam; Stein, Stephen W

    2014-04-01

    Pressurized metered dose inhalers (MDIs) are a long-standing method to treat diseases of the lung, such as asthma and chronic obstructive pulmonary disease. MDIs rely on the driving force of the propellant, which comprises the bulk of the MDI formulation, to atomize droplets containing drug and excipients, which ideally should deposit in the lungs. During the phase out of chlorofluorocarbon propellants and the introduction of more environmentally friendly hydrofluoroalkane propellants, many improvements were made to the methods of formulating for MDI drug delivery along with a greater understanding of formulation variables on product performance. This review presents a survey of challenges associated with formulating MDIs as solution or suspension products with one or more drugs, while considering the physicochemical properties of various excipients and how the addition of these excipients may impact overall product performance of the MDI. Propellants, volatile and nonvolatile cosolvents, surfactants, polymers, suspension stabilizers, and bulking agents are among the variety of excipients discussed in this review article. Furthermore, other formulation approaches, such as engineered excipient and drug-excipient particles, to deliver multiple drugs from a single MDI are also evaluated. PMID:24452499

  20. TH-A-19A-06: Site-Specific Comparison of Analytical and Monte Carlo Based Dose Calculations

    SciTech Connect

    Schuemann, J; Grassberger, C; Paganetti, H; Dowdell, S

    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) 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

  1. A system for individualized dosing of intravenous aminophylline using a programmable calculator.

    PubMed

    Mitsuoka, J C; Fleck, R J

    1984-01-01

    A program that calculates a value of clearance for an individual patient prior to reaching steady state in the early stages of aminophylline therapy is presented. The program is written for the Texas Instruments TI-59 programmable calculator and may be used with or without the PC-100C printer. The program can provide clinically useful information concerning projected plasma concentrations prior to reaching steady state with an accurate history of the dose administration and serum concentration determination. If the patient has not received xanthene therapy prior to admission, only one serum sample is required. If there has been prior drug exposure, a second serum sample is required. An iterative technique, which would be impractical to use without calculator assistance, is employed to make these determinations. PMID:6546320

  2. First macro Monte Carlo based commercial dose calculation module for electron beam treatment planning—new issues for clinical consideration

    NASA Astrophysics Data System (ADS)

    Ding, George X.; Duggan, Dennis M.; Coffey, Charles W.; Shokrani, Parvaneh; Cygler, Joanna E.

    2006-06-01

    The purpose of this study is to present our experience of commissioning, testing and use of the first commercial macro Monte Carlo based dose calculation algorithm for electron beam treatment planning and to investigate new issues regarding dose reporting (dose-to-water versus dose-to-medium) as well as statistical uncertainties for the calculations arising when Monte Carlo based systems are used in patient dose calculations. All phantoms studied were obtained by CT scan. The calculated dose distributions and monitor units were validated against measurements with film and ionization chambers in phantoms containing two-dimensional (2D) and three-dimensional (3D) type low- and high-density inhomogeneities at different source-to-surface distances. Beam energies ranged from 6 to 18 MeV. New required experimental input data for commissioning are presented. The result of validation shows an excellent agreement between calculated and measured dose distributions. The calculated monitor units were within 2% of measured values except in the case of a 6 MeV beam and small cutout fields at extended SSDs (>110 cm). The investigation on the new issue of dose reporting demonstrates the differences up to 4% for lung and 12% for bone when 'dose-to-medium' is calculated and reported instead of 'dose-to-water' as done in a conventional system. The accuracy of the Monte Carlo calculation is shown to be clinically acceptable even for very complex 3D-type inhomogeneities. As Monte Carlo based treatment planning systems begin to enter clinical practice, new issues, such as dose reporting and statistical variations, may be clinically significant. Therefore it is imperative that a consistent approach to dose reporting is used.

  3. Development of phantom and methodology for 3D and 4D dose intercomparisons for advanced lung radiotherapy

    NASA Astrophysics Data System (ADS)

    Caloz, Misael; Kafrouni, Marilyne; Leturgie, Quentin; Corde, Stéphanie; Downes, Simon; Lehmann, Joerg; Thwaites, David

    2015-01-01

    There are few reported intercomparisons or audits of combinations of advanced radiotherapy methods, particularly for 4D treatments. As part of an evaluation of the implementation of advanced radiotherapy technology, a phantom and associated methods, initially developed for in-house commissioning and QA of 4D lung treatments, has been developed further with the aim of using it for end-to-end dose intercomparison of 4D treatment planning and delivery. The respiratory thorax phantom can house moving inserts with variable speed (breathing rate) and motion amplitude. In one set-up mode it contains a small ion chamber for point dose measurements, or alternatively it can hold strips of radiochromic film to measure dose distributions. Initial pilot and feasibility measurements have been carried out in one hospital to thoroughly test the methods and procedures before using it more widely across a range of hospitals and treatment systems. Overall, the results show good agreement between measured and calculated doses and distributions, supporting the use of the phantom and methodology for multi-centre intercomparisons. However, before wider use, refinements of the method and analysis are currently underway particularly for the film measurements.

  4. Influence of z overscanning on normalized effective doses calculated for pediatric patients undergoing multidetector CT examinations

    SciTech Connect

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

    2007-04-15

    multidetector CT system were calculated. This data was found to depend strongly on CT acquisition mode and exposure parameters as well as patient age and sex. The effective dose from a pediatric CT scan performed in axial mode was always considerably lower compared to the corresponding scan performed in helical mode, due to the additional tissue regions exposed to the primary beam in helical examinations as a result of z overscanning.

  5. Influence of z overscanning on normalized effective doses calculated for pediatric patients undergoing multidetector CT examinations.

    PubMed

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

    2007-04-01

    multidetector CT system were calculated. This data was found to depend strongly on CT acquisition mode and exposure parameters as well as patient age and sex. The effective dose from a pediatric CT scan performed in axial mode was always considerably lower compared to the corresponding scan performed in helical mode, due to the additional tissue regions exposed to the primary beam in helical examinations as a result of z overscanning. PMID:17500447

  6. Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections

    SciTech Connect

    Jones, Bernard L. Westerly, David; Miften, Moyed

    2015-02-15

    Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. The authors developed and validated a method which uses these projections to determine the trajectory of and dose to highly mobile tumors during each fraction of treatment. Methods: CBCT images of a respiration phantom were acquired, the trajectory of which mimicked a lung tumor with high amplitude (up to 2.5 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each CBCT projection, and a Gaussian probability density function for the absolute BB position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two modifications of the trajectory reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation (Phase), and second, using the Monte Carlo (MC) method to sample the estimated Gaussian tumor position distribution. The accuracies of the proposed methods were evaluated by comparing the known and calculated BB trajectories in phantom-simulated clinical scenarios using abdominal tumor volumes. Results: With all methods, the mean position of the BB was determined with accuracy better than 0.1 mm, and root-mean-square trajectory errors averaged 3.8% ± 1.1% of the marker amplitude. Dosimetric calculations using Phase methods were more accurate, with mean absolute error less than 0.5%, and with error less than 1% in the highest-noise trajectory. MC-based trajectories prevent the overestimation of dose, but when viewed in an absolute sense, add a small amount of dosimetric error (<0.1%). Conclusions: Marker trajectory and target dose-of-the-day were accurately calculated using CBCT projections. This technique provides a method to evaluate highly mobile tumors using ordinary CBCT data, and could facilitate better strategies to mitigate or compensate for motion during

  7. Comparison of dose calculation algorithms in slab phantoms with cortical bone equivalent heterogeneities

    SciTech Connect

    Carrasco, P.; Jornet, N.; Duch, M. A.; Panettieri, V.; Weber, L.; Eudaldo, T.; Ginjaume, M.; Ribas, M.

    2007-08-15

    To evaluate the dose values predicted by several calculation algorithms in two treatment planning systems, Monte Carlo (MC) simulations and measurements by means of various detectors were performed in heterogeneous layer phantoms with water- and bone-equivalent materials. Percentage depth doses (PDDs) were measured with thermoluminescent dosimeters (TLDs), metal-oxide semiconductor field-effect transistors (MOSFETs), plane parallel and cylindrical ionization chambers, and beam profiles with films. The MC code used for the simulations was the PENELOPE code. Three different field sizes (10x10, 5x5, and 2x2 cm{sup 2}) were studied in two phantom configurations and a bone equivalent material. These two phantom configurations contained heterogeneities of 5 and 2 cm of bone, respectively. We analyzed the performance of four correction-based algorithms and one based on convolution superposition. The correction-based algorithms were the Batho, the Modified Batho, the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system (TPS), and the Helax-TMS Pencil Beam from the Helax-TMS (Nucletron) TPS. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. All the correction-based calculation algorithms underestimated the dose inside the bone-equivalent material for 18 MV compared to MC simulations. The maximum underestimation, in terms of root-mean-square (RMS), was about 15% for the Helax-TMS Pencil Beam (Helax-TMS PB) for a 2x2 cm{sup 2} field inside the bone-equivalent material. In contrast, the Collapsed Cone algorithm yielded values around 3%. A more complex behavior was found for 6 MV where the Collapsed Cone performed less well, overestimating the dose inside the heterogeneity in 3%-5%. The rebuildup in the interface bone-water and the penumbra shrinking in high-density media were not predicted by any of the calculation algorithms except the Collapsed Cone, and only the MC simulations matched the experimental values

  8. Comparison of dose calculation algorithms in slab phantoms with cortical bone equivalent heterogeneities.

    PubMed

    Carrasco, P; Jornet, N; Duch, M A; Panettieri, V; Weber, L; Eudaldo, T; Ginjaume, M; Ribas, M

    2007-08-01

    To evaluate the dose values predicted by several calculation algorithms in two treatment planning systems, Monte Carlo (MC) simulations and measurements by means of various detectors were performed in heterogeneous layer phantoms with water- and bone-equivalent materials. Percentage depth doses (PDDs) were measured with thermoluminescent dosimeters (TLDs), metal-oxide semiconductor field-effect transistors (MOSFETs), plane parallel and cylindrical ionization chambers, and beam profiles with films. The MC code used for the simulations was the PENELOPE code. Three different field sizes (10 x 10, 5 x 5, and 2 x 2 cm2) were studied in two phantom configurations and a bone equivalent material. These two phantom configurations contained heterogeneities of 5 and 2 cm of bone, respectively. We analyzed the performance of four correction-based algorithms and one based on convolution superposition. The correction-based algorithms were the Batho, the Modified Batho, the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system (TPS), and the Helax-TMS Pencil Beam from the Helax-TMS (Nucletron) TPS. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. All the correction-based calculation algorithms underestimated the dose inside the bone-equivalent material for 18 MV compared to MC simulations. The maximum underestimation, in terms of root-mean-square (RMS), was about 15% for the Helax-TMS Pencil Beam (Helax-TMS PB) for a 2 x 2 cm2 field inside the bone-equivalent material. In contrast, the Collapsed Cone algorithm yielded values around 3%. A more complex behavior was found for 6 MV where the Collapsed Cone performed less well, overestimating the dose inside the heterogeneity in 3%-5%. The rebuildup in the interface bone-water and the penumbra shrinking in high-density media were not predicted by any of the calculation algorithms except the Collapsed Cone, and only the MC simulations matched the experimental values

  9. Calculation of Accumulated Radiation Doses to Man from Radionuclides Found in Food Products and from Radionuclides in the Environment.

    1981-02-17

    PABLM calculates internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. It can be used to calculate accumulated doses to 23 possible body organs or tissues for any one or a combination of radionuclides. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides in themore » environment after the releases have ended. Radioactive decay is considered during the release of radionuclides, after they are deposited on the plants or ground, and during holdup of food after harvest. A chain decay scheme is used; it includes branching to account for transitions to and from isomeric states. Doses may be calculated for either a maximum-exposed individual or for a population group. The doses calculated are accumulated doses from continuous chronic exposure. A first-year committed dose is calculated as well as an integrated dose for a selected number of years.« less

  10. The neutron dose conversion coefficients calculation in human tooth enamel in an anthropomorphic phantom.

    PubMed

    Khailov, A M; Ivannikov, A I; Skvortsov, V G; Stepanenko, V F; Tsyb, A F; Trompier, F; Hoshi, M

    2010-02-01

    In the present study, MCNP4B simulation code is used to simulate neutron and photon transport. It gives the conversion coefficients that relate neutron fluence to the dose in tooth enamel (molars and pre-molars only) for 20 energy groups of monoenergetic neutrons with energies from 10-9 to 20 MeV for five different irradiation geometries. The data presented are intended to provide the basis for connection between EPR dose values and standard protection quantities defined in ICRP Publication 74. The results of the calculations for critical organs were found to be consistent with ICRP data, with discrepancies generally less than 10% for the fast neutrons. The absorbed dose in enamel was found to depend strongly on the incident neutron energy for neutrons over 10 keV. The dependence of the data on the irradiation geometry is also shown. Lower bound estimates of enamel radiation sensitivity to neutrons were made using obtained coefficients for the secondary photons. Depending on neutron energy, tooth enamel was shown to register 10-120% of the total neutron dose in the human body in the case of pure neutron exposure and AP irradiation geometry. PMID:20065707

  11. Calculated organ doses for Mayak production association central hall using ICRP and MCNP.

    PubMed

    Choe, Dong-Ok; Shelkey, Brenda N; Wilde, Justin L; Walk, Heidi A; Slaughter, David M

    2003-03-01

    As part of an ongoing dose reconstruction project, equivalent organ dose rates from photons and neutrons were estimated using the energy spectra measured in the central hall above the graphite reactor core located in the Russian Mayak Production Association facility. Reconstruction of the work environment was necessary due to the lack of personal dosimeter data for neutrons in the time period prior to 1987. A typical worker scenario for the central hall was developed for the Monte Carlo Neutron Photon-4B (MCNP) code. The resultant equivalent dose rates for neutrons and photons were compared with the equivalent dose rates derived from calculations using the conversion coefficients in the International Commission on Radiological Protection Publications 51 and 74 in order to validate the model scenario for this Russian facility. The MCNP results were in good agreement with the results of the ICRP publications indicating the modeling scenario was consistent with actual work conditions given the spectra provided. The MCNP code will allow for additional orientations to accurately reflect source locations. PMID:12645766

  12. Using the Monte Carlo technique to calculate dose conversion coefficients for medical professionals in interventional radiology

    NASA Astrophysics Data System (ADS)

    Santos, W. S.; Carvalho, A. B., Jr.; Hunt, J. G.; Maia, A. F.

    2014-02-01

    The objective of this study was to estimate doses in the physician and the nurse assistant at different positions during interventional radiology procedures. In this study, effective doses obtained for the physician and at points occupied by other workers were normalised by air kerma-area product (KAP). The simulations were performed for two X-ray spectra (70 kVp and 87 kVp) using the radiation transport code MCNPX (version 2.7.0), and a pair of anthropomorphic voxel phantoms (MASH/FASH) used to represent both the patient and the medical professional at positions from 7 cm to 47 cm from the patient. The X-ray tube was represented by a point source positioned in the anterior posterior (AP) and posterior anterior (PA) projections. The CC can be useful to calculate effective doses, which in turn are related to stochastic effects. With the knowledge of the values of CCs and KAP measured in an X-ray equipment, at a similar exposure, medical professionals will be able to know their own effective dose.

  13. Safety in numbers 1: Essential numerical and scientific principles underpinning medication dose calculation.

    PubMed

    Young, Simon; Weeks, Keith W; Hutton, B Meriel

    2013-03-01

    Registered nurses spend up to 40% of their professional clinical practice engaged in the art and science of medication dosage calculation problem-solving (MDC-PS). In advancing this patient safety critical discipline it is our position that as a profession we must first situate MDC-PS within the context of the wider features of the nursing numeracy, medicines management and clinical pharmacokinetic domains that inform its practice. This paper focuses on the essential relationship between numeracy, healthcare numeracy, medicines management, pharmacokinetics and MDC-PS. We present a taxonomy of generic numerical competencies for the pre-registration curriculum, with examples of essential medication dosage calculation requirements mapped to each skills domain. This is followed by a review of the symbols and measurement units that represent essential components of calculation competence in healthcare and medicines management practice. Finally we outline the fundamental pharmacokinetic knowledge that explains how the body deals with medication and we illustrate through clinical correlations why numeric and scientific knowledge and skills must be mastered to ensure safe dosage calculation and medicines management practice. The findings inform nurse education practice via advancing our understanding of a number of issues, including a unified taxonomy of generic numerical competencies mapped to the 42 revised UK Nursing and Midwifery Council (NMC) Essential Skills Clusters (NMC, 2010a; NMC, 2010b). PMID:23273945

  14. Lung Dose Calculation With SPECT/CT for {sup 90}Yittrium Radioembolization of Liver Cancer

    SciTech Connect

    Yu, Naichang; Srinivas, Shaym M.; DiFilippo, Frank P.; Shrikanthan, Sankaran; Levitin, Abraham; McLennan, Gordon; Spain, James; Xia, Ping; Wilkinson, Allan

    2013-03-01

    Purpose: To propose a new method to estimate lung mean dose (LMD) using technetium-99m labeled macroaggregated albumin ({sup 99m}Tc-MAA) single photon emission CT (SPECT)/CT for {sup 90}Yttrium radioembolization of liver tumors and to compare the LMD estimated using SPECT/CT with clinical estimates of LMD using planar gamma scintigraphy (PS). Methods and Materials: Images of 71 patients who had SPECT/CT and PS images of {sup 99m}Tc-MAA acquired before TheraSphere radioembolization of liver cancer were analyzed retrospectively. LMD was calculated from the PS-based lung shunt assuming a lung mass of 1 kg and 50 Gy per GBq of injected activity shunted to the lung. For the SPECT/CT-based estimate, the LMD was calculated with the activity concentration and lung volume derived from SPECT/CT. The effect of attenuation correction and the patient's breathing on the calculated LMD was studied with the SPECT/CT. With these effects correctly taken into account in a more rigorous fashion, we compared the LMD calculated with SPECT/CT with the LMD calculated with PS. Results: The mean dose to the central region of the lung leads to a more accurate estimate of LMD. Inclusion of the lung region around the diaphragm in the calculation leads to an overestimate of LMD due to the misregistration of the liver activity to the lung from the patient's breathing. LMD calculated based on PS is a poor predictor of the actual LMD. For the subpopulation with large lung shunt, the mean overestimation from the PS method for the lung shunt was 170%. Conclusions: A new method of calculating the LMD for TheraSphere and SIR-Spheres radioembolization of liver cancer based on {sup 99m}Tc-MAA SPECT/CT is presented. The new method provides a more accurate estimate of radiation risk to the lungs. For patients with a large lung shunt calculated from PS, a recalculation of LMD based on SPECT/CT is recommended.

  15. Accuracy of pencil-beam redefinition algorithm dose calculations in patient-like cylindrical phantoms for bolus electron conformal therapy

    SciTech Connect

    Carver, Robert L.; Hogstrom, Kenneth R.; Chu, Connel; Fields, Robert S.; Sprunger, Conrad P.

    2013-07-15

    Purpose: The purpose of this study was to document the improved accuracy of the pencil beam redefinition algorithm (PBRA) compared to the pencil beam algorithm (PBA) for bolus electron conformal therapy using cylindrical patient phantoms based on patient computed tomography (CT) scans of retromolar trigone and nose cancer.Methods: PBRA and PBA electron dose calculations were compared with measured dose in retromolar trigone and nose phantoms both with and without bolus. For the bolus treatment plans, a radiation oncologist outlined a planning target volume (PTV) on the central axis slice of the CT scan for each phantom. A bolus was designed using the planning.decimal{sup Registered-Sign} (p.d) software (.decimal, Inc., Sanford, FL) to conform the 90% dose line to the distal surface of the PTV. Dose measurements were taken with thermoluminescent dosimeters placed into predrilled holes. The Pinnacle{sup 3} (Philips Healthcare, Andover, MD) treatment planning system was used to calculate PBA dose distributions. The PBRA dose distributions were calculated with an in-house C++ program. In order to accurately account for the phantom materials a table correlating CT number to relative electron stopping and scattering powers was compiled and used for both PBA and PBRA dose calculations. Accuracy was determined by comparing differences in measured and calculated dose, as well as distance to agreement for each measurement point.Results: The measured doses had an average precision of 0.9%. For the retromolar trigone phantom, the PBRA dose calculations had an average {+-}1{sigma} dose difference (calculated - measured) of -0.65%{+-} 1.62% without the bolus and -0.20%{+-} 1.54% with the bolus. The PBA dose calculation had an average dose difference of 0.19%{+-} 3.27% without the bolus and -0.05%{+-} 3.14% with the bolus. For the nose phantom, the PBRA dose calculations had an average dose difference of 0.50%{+-} 3.06% without bolus and -0.18%{+-} 1.22% with the bolus. The PBA

  16. A generalized 2D pencil beam scaling algorithm for proton dose calculation in heterogeneous slab geometries

    PubMed Central

    Westerly, David C.; Mo, Xiaohu; Tomé, Wolfgang A.; Mackie, Thomas R.; DeLuca, Paul M.

    2013-01-01

    Purpose: Pencil beam algorithms are commonly used for proton therapy dose calculations. Szymanowski and Oelfke [“Two-dimensional pencil beam scaling: An improved proton dose algorithm for heterogeneous media,” Phys. Med. Biol. 47, 3313–3330 (2002)10.1088/0031-9155/47/18/304] developed a two-dimensional (2D) scaling algorithm which accurately models the radial pencil beam width as a function of depth in heterogeneous slab geometries using a scaled expression for the radial kernel width in water as a function of depth and kinetic energy. However, an assumption made in the derivation of the technique limits its range of validity to cases where the input expression for the radial kernel width in water is derived from a local scattering power model. The goal of this work is to derive a generalized form of 2D pencil beam scaling that is independent of the scattering power model and appropriate for use with any expression for the radial kernel width in water as a function of depth. Methods: Using Fermi-Eyges transport theory, the authors derive an expression for the radial pencil beam width in heterogeneous slab geometries which is independent of the proton scattering power and related quantities. The authors then perform test calculations in homogeneous and heterogeneous slab phantoms using both the original 2D scaling model and the new model with expressions for the radial kernel width in water computed from both local and nonlocal scattering power models, as well as a nonlocal parameterization of Molière scattering theory. In addition to kernel width calculations, dose calculations are also performed for a narrow Gaussian proton beam. Results: Pencil beam width calculations indicate that both 2D scaling formalisms perform well when the radial kernel width in water is derived from a local scattering power model. Computing the radial kernel width from a nonlocal scattering model results in the local 2D scaling formula under-predicting the pencil beam width by as

  17. WRAITH - A Computer Code for Calculating Internal and External Doses Resulting From An Atmospheric Release of Radioactive Material

    SciTech Connect

    Scherpelz, R. I.; Borst, F. J.; Hoenes, G. R.

    1980-12-01

    WRAITH is a FORTRAN computer code which calculates the doses received by a standard man exposed to an accidental release of radioactive material. The movement of the released material through the atmosphere is calculated using a bivariate straight-line Gaussian distribution model, with Pasquill values for standard deviations. The quantity of material in the released cloud is modified during its transit time to account for radioactive decay and daughter production. External doses due to exposure to the cloud can be calculated using a semi-infinite cloud approximation. In situations where the semi-infinite cloud approximation is not a good one, the external dose can be calculated by a "finite plume" three-dimensional point-kernel numerical integration technique. Internal doses due to acute inhalation are cal.culated using the ICRP Task Group Lung Model and a four-segmented gastro-intestinal tract model. Translocation of the material between body compartments and retention in the body compartments are calculated using multiple exponential retention functions. Internal doses to each organ are calculated as sums of cross-organ doses, with each target organ irradiated by radioactive material in a number of source organs. All doses are calculated in rads, with separate values determined for high-LET and low-LET radiation.

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

    PubMed

    Takahashi, F; Endo, A

    2007-01-01

    A system utilising radiation transport codes has been developed to derive accurate dose distributions in a human body for radiological accidents. A suitable model is quite essential for a numerical analysis. Therefore, two tools were developed to setup a 'problem-dependent' input file, defining a radiation source and an exposed person to simulate the radiation transport in an accident with the Monte Carlo calculation codes-MCNP and MCNPX. Necessary resources are defined by a dialogue method with a generally used personal computer for both the tools. The tools prepare human body and source models described in the input file format of the employed Monte Carlo codes. The tools were validated for dose assessment in comparison with a past criticality accident and a hypothesized exposure. PMID:17510203

  19. An automated approach to calculating the daily dose of tacrolimus in electronic health records.

    PubMed

    Xu, Hua; Doan, Son; Birdwell, Kelly A; Cowan, James D; Vincz, Andrew J; Haas, David W; Basford, Melissa A; Denny, Joshua C

    2010-01-01

    Clinical research often requires extracting detailed drug information, such as medication names and dosages, from Electronic Health Records (EHR). Since medication information is often recorded as both structured and unstructured formats in the EHR, extracting all the relevant drug mentions and determining the daily dose of a medication for a selected patient at a given date can be a challenging and time-consuming task. In this paper, we present an automated approach using natural language processing to calculate daily doses of medications mentioned in clinical text, using tacrolimus as a test case. We evaluated this method using data sets from four different types of unstructured clinical data. Our results showed that the system achieved precisions of 0.90-1.00 and recalls of 0.81-1.00. PMID:21347153

  20. A BrachyPhantom for verification of dose calculation of HDR brachytherapy planning system

    SciTech Connect

    Austerlitz, C.; Campos, C. A. T.

    2013-11-15

    Purpose: To develop a calibration phantom for {sup 192}Ir high dose rate (HDR) brachytherapy units that renders possible the direct measurement of absorbed dose to water and verification of treatment planning system.Methods: A phantom, herein designated BrachyPhantom, consists of a Solid Water™ 8-cm high cylinder with a diameter of 14 cm cavity in its axis that allows the positioning of an A1SL ionization chamber with its reference measuring point at the midheight of the cylinder's axis. Inside the BrachyPhantom, at a 3-cm radial distance from the chamber's reference measuring point, there is a circular channel connected to a cylindrical-guide cavity that allows the insertion of a 6-French flexible plastic catheter from the BrachyPhantom surface. The PENELOPE Monte Carlo code was used to calculate a factor, P{sub sw}{sup lw}, to correct the reading of the ionization chamber to a full scatter condition in liquid water. The verification of dose calculation of a HDR brachytherapy treatment planning system was performed by inserting a catheter with a dummy source in the phantom channel and scanning it with a CT. The CT scan was then transferred to the HDR computer program in which a multiple treatment plan was programmed to deliver a total dose of 150 cGy to the ionization chamber. The instrument reading was then converted to absorbed dose to water using the N{sub gas} formalism and the P{sub sw}{sup lw} factor. Likewise, the absorbed dose to water was calculated using the source strength, S{sub k}, values provided by 15 institutions visited in this work.Results: A value of 1.020 (0.09%, k= 2) was found for P{sub sw}{sup lw}. The expanded uncertainty in the absorbed dose assessed with the BrachyPhantom was found to be 2.12% (k= 1). To an associated S{sub k} of 27.8 cGy m{sup 2} h{sup −1}, the total irradiation time to deliver 150 cGy to the ionization chamber point of reference was 161.0 s. The deviation between the absorbed doses to water assessed with the Brachy

  1. Ultraviolet radiation dose calculation for algal suspensions using UVA and UVB extinction coefficients.

    PubMed

    Navarro, Enrique; Muñiz, Selene; Korkaric, Muris; Wagner, Bettina; de Cáceres, Miquel; Behra, Renata

    2014-03-01

    Although the biological importance of ultraviolet light (UVR) attenuation has been recognised in marine and freshwater environments, it is not generally considered in in vitro ecotoxicological studies using algal cell suspensions. In this study, UVA and UVB extinction were determined for cultures of algae with varying cell densities, and the data were used to calculate the corresponding extinction coefficients for both UVA and UVB wavelength ranges. Integrating the Beer-Lambert equation to account for changes in the radiation intensity reaching each depth, from the surface until the bottom of the experimental vessel, we obtained the average UVA and UVB intensity to which the cultured algal cells were exposed. We found that UVR intensity measured at the surface of Chlamydomonas reinhardtii cultures lead to a overestimation of the UVR dose received by the algae by 2-40 times. The approach used in this study allowed for a more accurate estimation of UVA and UVB doses. PMID:24607609

  2. Effects of CT based Voxel Phantoms on Dose Distribution Calculated with Monte Carlo Method

    NASA Astrophysics Data System (ADS)

    Chen, Chaobin; Huang, Qunying; Wu, Yican

    2005-04-01

    A few CT-based voxel phantoms were produced to investigate the sensitivity of Monte Carlo simulations of x-ray beam and electron beam to the proportions of elements and the mass densities of the materials used to express the patient's anatomical structure. The human body can be well outlined by air, lung, adipose, muscle, soft bone and hard bone to calculate the dose distribution with Monte Carlo method. The effects of the calibration curves established by using various CT scanners are not clinically significant based on our investigation. The deviation from the values of cumulative dose volume histogram derived from CT-based voxel phantoms is less than 1% for the given target.

  3. Peregrine monte carlo dose calculations for radiotherapy using clinically realistic neutron and proton beams

    SciTech Connect

    Cox, L. J., LLNL

    1997-06-16

    Lawrence Livermore National Laboratory (LLNL) has developed an all-particle Monte Carlo radiotherapy dose calculation code--PEREGRINE--for use in clinical radiation oncology. For PEREGRINE, we have assembled high-energy evaluated nuclear databases; created radiation source characterization and sampling algorithms; and simulated and characterized clinical beams for treatment with photons, neutrons and protons. Spectra are available for the Harper Hospital (Detroit, U.S.A.) Be(d,n) neutron therapy beam, the National Accelerator Centre (NAC, Faure, S.A.) Be(p,n) neutron therapy beam and many of the operating modes of the Loma Linda University Medical Center (LLUMC, Loma Linda, USA) proton treatment center. These beam descriptions are being used in PEREGRINE for Monte Carlo dose calculations on clinical configurations for comparisons to measurements. The methods of defining and sampling the beam phase space characterizations are discussed. We show calculations using these clinical beams compared to measurements in homogeneous water phantoms. The state of PEREGRINE's high energy neutron and proton transport database, PCSL, is reviewed and the remaining issues involving nuclear data needs for PEREGRINE are addressed.

  4. 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. PMID:19359853

  5. Poster — Thur Eve — 14: Improving Tissue Segmentation for Monte Carlo Dose Calculation using DECT

    SciTech Connect

    Di Salvio, A.; Bedwani, S.; Carrier, J-F.; Bouchard, H.

    2014-08-15

    Purpose: To improve Monte Carlo dose calculation accuracy through a new tissue segmentation technique with dual energy CT (DECT). Methods: Electron density (ED) and effective atomic number (EAN) can be extracted directly from DECT data with a stoichiometric calibration method. Images are acquired with Monte Carlo CT projections using the user code egs-cbct and reconstructed using an FDK backprojection algorithm. Calibration is performed using projections of a numerical RMI phantom. A weighted parameter algorithm then uses both EAN and ED to assign materials to voxels from DECT simulated images. This new method is compared to a standard tissue characterization from single energy CT (SECT) data using a segmented calibrated Hounsfield unit (HU) to ED curve. Both methods are compared to the reference numerical head phantom. Monte Carlo simulations on uniform phantoms of different tissues using dosxyz-nrc show discrepancies in depth-dose distributions. Results: Both SECT and DECT segmentation methods show similar performance assigning soft tissues. Performance is however improved with DECT in regions with higher density, such as bones, where it assigns materials correctly 8% more often than segmentation with SECT, considering the same set of tissues and simulated clinical CT images, i.e. including noise and reconstruction artifacts. Furthermore, Monte Carlo results indicate that kV photon beam depth-dose distributions can double between two tissues of density higher than muscle. Conclusions: A direct acquisition of ED and the added information of EAN with DECT data improves tissue segmentation and increases the accuracy of Monte Carlo dose calculation in kV photon beams.

  6. Dose-Effect Relationship in Chemoradiotherapy for Locally Advanced Rectal Cancer: A Randomized Trial Comparing Two Radiation Doses

    SciTech Connect

    Jakobsen, Anders; Ploen, John; Vuong, Te; Appelt, Ane; Lindebjerg, Jan; Rafaelsen, Soren R.

    2012-11-15

    Purpose: Locally advanced rectal cancer represents a major therapeutic challenge. Preoperative chemoradiation therapy is considered standard, but little is known about the dose-effect relationship. The present study represents a dose-escalation phase III trial comparing 2 doses of radiation. Methods and Materials: The inclusion criteria were resectable T3 and T4 tumors with a circumferential margin of {<=}5 mm on magnetic resonance imaging. The patients were randomized to receive 50.4 Gy in 28 fractions to the tumor and pelvic lymph nodes (arm A) or the same treatment supplemented with an endorectal boost given as high-dose-rate brachytherapy (10 Gy in 2 fractions; arm B). Concomitant chemotherapy, uftoral 300 mg/m{sup 2} and L-leucovorin 22.5 mg/d, was added to both arms on treatment days. The primary endpoint was complete pathologic remission. The secondary endpoints included tumor response and rate of complete resection (R0). Results: The study included 248 patients. No significant difference was found in toxicity or surgical complications between the 2 groups. Based on intention to treat, no significant difference was found in the complete pathologic remission rate between the 2 arms (18% and 18%). The rate of R0 resection was different in T3 tumors (90% and 99%; P=.03). The same applied to the rate of major response (tumor regression grade, 1+2), 29% and 44%, respectively (P=.04). Conclusions: This first randomized trial comparing 2 radiation doses indicated that the higher dose increased the rate of major response by 50% in T3 tumors. The endorectal boost is feasible, with no significant increase in toxicity or surgical complications.

  7. Development and application of a random lung model for dose calculations in radiotherapy

    NASA Astrophysics Data System (ADS)

    Liang, Liang

    Radiotherapy requires accurate dose calculations in the human body, especially in disease sites with large variations of electron density in neighboring tissues, such as the lung. Currently, the lung is modeled by a voxelized geometry interpolated from computed tomography (CT) scans to various resolutions. The simplest such voxelized lung, the atomic mix model, is a homogenized whole lung with a volume-averaged bulk density. However, according traditional transport theory, even the relatively fine CT voxelization of the lung is not valid, due to the extremely small mean free path (MFP) of the electrons. The purpose of this thesis is to study the impact of the lung's heterogeneities on dose calculations in lung treatment planning. We first extend the traditional atomic mix theory for charged particles by approximating the Boltzmann equation for electrons to its Fokker-Planck (FP) limit, and then applying a formal asymptotic analysis to the BFP equation. This analysis raises the length scale for homogenizing a heterogeneous medium from the electron mean free path (MFP) to the much larger electron transport MFP. Then, using the lung's anatomical data and our new atomic mix theory, we build a realistic 2 1/2-D random lung model. The dose distributions for representative realizations of the random lung model are compared to those from the atomic mix approximation of the random lung model, showing that significant perturbations may occur with small field sizes and large lung structures. We also apply our random lung model to a more realistic lung phantom and investigate the effect of CT resolutions on lung treatment planning. We show that, compared to the reference 1 x 1 mm2 CT resolution, a 2 x 2 mm2 CT resolution is sufficient to voxelize the lung, while significant deviations in dose can be observed with a larger 4 x 4 mm 2 CT resolution. We use the Monte Carlo method extensively in this thesis, to avoid systematic errors caused by inaccurate heterogeneity corrections

  8. Calculation of the radiation doses occurring in the human body for inadvertent ingestion of soil and other soil exposure pathways

    NASA Astrophysics Data System (ADS)

    Oner, F.; Okumuolu, N.

    2003-11-01

    We estimate the radiation doses in the human body, in the Gudalore region in India, following the inadvertent ingestion of soil and exposure to other soil pathways by measuring Th-232, U-238, and K-40. We estimate the equivalent dose in eleven different organs and the absorbed dose calculations for the whole body. The annual effective doses are calculated, the lowest is in Kariyasolai at 7.8 x 10(-3) mSv whereas the highest is in Ponnur at 8.9 x 10(-2) mSv. In all regions, the lowest equivalent doses through inadvertent soil ingestion are calculated in the kidney and thyroid whereas the highest doses are in the red marrow and on the bone surface.

  9. A comparison between anisotropic analytical and multigrid superposition dose calculation algorithms in radiotherapy treatment planning.

    PubMed

    Wu, Vincent W C; Tse, Teddy K H; Ho, Cola L M; Yeung, Eric C Y

    2013-01-01

    Monte Carlo (MC) simulation is currently the most accurate dose calculation algorithm in radiotherapy planning but requires relatively long processing time. Faster model-based algorithms such as the anisotropic analytical algorithm (AAA) by the Eclipse treatment planning system and multigrid superposition (MGS) by the XiO treatment planning system are 2 commonly used algorithms. This study compared AAA and MGS against MC, as the gold standard, on brain, nasopharynx, lung, and prostate cancer patients. Computed tomography of 6 patients of each cancer type was used. The same hypothetical treatment plan using the same machine and treatment prescription was computed for each case by each planning system using their respective dose calculation algorithm. The doses at reference points including (1) soft tissues only, (2) bones only, (3) air cavities only, (4) soft tissue-bone boundary (Soft/Bone), (5) soft tissue-air boundary (Soft/Air), and (6) bone-air boundary (Bone/Air), were measured and compared using the mean absolute percentage error (MAPE), which was a function of the percentage dose deviations from MC. Besides, the computation time of each treatment plan was recorded and compared. The MAPEs of MGS were significantly lower than AAA in all types of cancers (p<0.001). With regards to body density combinations, the MAPE of AAA ranged from 1.8% (soft tissue) to 4.9% (Bone/Air), whereas that of MGS from 1.6% (air cavities) to 2.9% (Soft/Bone). The MAPEs of MGS (2.6%±2.1) were significantly lower than that of AAA (3.7%±2.5) in all tissue density combinations (p<0.001). The mean computation time of AAA for all treatment plans was significantly lower than that of the MGS (p<0.001). Both AAA and MGS algorithms demonstrated dose deviations of less than 4.0% in most clinical cases and their performance was better in homogeneous tissues than at tissue boundaries. In general, MGS demonstrated relatively smaller dose deviations than AAA but required longer computation time

  10. A comparison between anisotropic analytical and multigrid superposition dose calculation algorithms in radiotherapy treatment planning

    SciTech Connect

    Wu, Vincent W.C.; Tse, Teddy K.H.; Ho, Cola L.M.; Yeung, Eric C.Y.

    2013-07-01

    Monte Carlo (MC) simulation is currently the most accurate dose calculation algorithm in radiotherapy planning but requires relatively long processing time. Faster model-based algorithms such as the anisotropic analytical algorithm (AAA) by the Eclipse treatment planning system and multigrid superposition (MGS) by the XiO treatment planning system are 2 commonly used algorithms. This study compared AAA and MGS against MC, as the gold standard, on brain, nasopharynx, lung, and prostate cancer patients. Computed tomography of 6 patients of each cancer type was used. The same hypothetical treatment plan using the same machine and treatment prescription was computed for each case by each planning system using their respective dose calculation algorithm. The doses at reference points including (1) soft tissues only, (2) bones only, (3) air cavities only, (4) soft tissue-bone boundary (Soft/Bone), (5) soft tissue-air boundary (Soft/Air), and (6) bone-air boundary (Bone/Air), were measured and compared using the mean absolute percentage error (MAPE), which was a function of the percentage dose deviations from MC. Besides, the computation time of each treatment plan was recorded and compared. The MAPEs of MGS were significantly lower than AAA in all types of cancers (p<0.001). With regards to body density combinations, the MAPE of AAA ranged from 1.8% (soft tissue) to 4.9% (Bone/Air), whereas that of MGS from 1.6% (air cavities) to 2.9% (Soft/Bone). The MAPEs of MGS (2.6%±2.1) were significantly lower than that of AAA (3.7%±2.5) in all tissue density combinations (p<0.001). The mean computation time of AAA for all treatment plans was significantly lower than that of the MGS (p<0.001). Both AAA and MGS algorithms demonstrated dose deviations of less than 4.0% in most clinical cases and their performance was better in homogeneous tissues than at tissue boundaries. In general, MGS demonstrated relatively smaller dose deviations than AAA but required longer computation time.

  11. Characterizing a proton beam scanning system for Monte Carlo dose calculation in patients

    NASA Astrophysics Data System (ADS)

    Grassberger, C.; Lomax, Anthony; Paganetti, H.

    2015-01-01

    The presented work has two goals. First, to demonstrate the feasibility of accurately characterizing a proton radiation field at treatment head exit for Monte Carlo dose calculation of active scanning patient treatments. Second, to show that this characterization can be done based on measured depth dose curves and spot size alone, without consideration of the exact treatment head delivery system. This is demonstrated through calibration of a Monte Carlo code to the specific beam lines of two institutions, Massachusetts General Hospital (MGH) and Paul Scherrer Institute (PSI). Comparison of simulations modeling the full treatment head at MGH to ones employing a parameterized phase space of protons at treatment head exit reveals the adequacy of the method for patient simulations. The secondary particle production in the treatment head is typically below 0.2% of primary fluence, except for low-energy electrons (<0.6 MeV for 230 MeV protons), whose contribution to skin dose is negligible. However, there is significant difference between the two methods in the low-dose penumbra, making full treatment head simulations necessary to study out-of-field effects such as secondary cancer induction. To calibrate the Monte Carlo code to measurements in a water phantom, we use an analytical Bragg peak model to extract the range-dependent energy spread at the two institutions, as this quantity is usually not available through measurements. Comparison of the measured with the simulated depth dose curves demonstrates agreement within 0.5 mm over the entire energy range. Subsequently, we simulate three patient treatments with varying anatomical complexity (liver, head and neck and lung) to give an example how this approach can be employed to investigate site-specific discrepancies between treatment planning system and Monte Carlo simulations.

  12. Characterizing a proton beam scanning system for Monte Carlo dose calculation in patients.

    PubMed

    Grassberger, C; Lomax, Anthony; Paganetti, H

    2015-01-21

    The presented work has two goals. First, to demonstrate the feasibility of accurately characterizing a proton radiation field at treatment head exit for Monte Carlo dose calculation of active scanning patient treatments. Second, to show that this characterization can be done based on measured depth dose curves and spot size alone, without consideration of the exact treatment head delivery system. This is demonstrated through calibration of a Monte Carlo code to the specific beam lines of two institutions, Massachusetts General Hospital (MGH) and Paul Scherrer Institute (PSI). Comparison of simulations modeling the full treatment head at MGH to ones employing a parameterized phase space of protons at treatment head exit reveals the adequacy of the method for patient simulations. The secondary particle production in the treatment head is typically below 0.2% of primary fluence, except for low-energy electrons (<0.6 MeV for 230 MeV protons), whose contribution to skin dose is negligible. However, there is significant difference between the two methods in the low-dose penumbra, making full treatment head simulations necessary to study out-of-field effects such as secondary cancer induction. To calibrate the Monte Carlo code to measurements in a water phantom, we use an analytical Bragg peak model to extract the range-dependent energy spread at the two institutions, as this quantity is usually not available through measurements. Comparison of the measured with the simulated depth dose curves demonstrates agreement within 0.5 mm over the entire energy range. Subsequently, we simulate three patient treatments with varying anatomical complexity (liver, head and neck and lung) to give an example how this approach can be employed to investigate site-specific discrepancies between treatment planning system and Monte Carlo simulations. PMID:25549079

  13. Preliminary results of 3D dose calculations with MCNP-4B code from a SPECT image.

    PubMed

    Rodríguez Gual, M; Lima, F F; Sospedra Alfonso, R; González González, J; Calderón Marín, C

    2004-01-01

    Interface software was developed to generate the input file to run Monte Carlo MCNP-4B code from medical image in Interfile format version 3.3. The software was tested using a spherical phantom of tomography slides with known cumulated activity distribution in Interfile format generated with IMAGAMMA medical image processing system. The 3D dose calculation obtained with Monte Carlo MCNP-4B code was compared with the voxel S factor method. The results show a relative error between both methods less than 1 %. PMID:15625058

  14. Biological shielding assessment and dose rate calculation for a neutron inspection portal

    NASA Astrophysics Data System (ADS)

    Donzella, A.; Bonomi, G.; Giroletti, E.; Zenoni, A.

    2012-04-01

    With reference to the prototype of neutron inspection portal built and successfully tested in the Rijeka seaport (Croatia) within the EURITRACK (EURopean Illicit Trafficking Countermeasures Kit) project, an assessment of the biological shielding in different set-up configurations of a future portal has been calculated with MCNP Monte Carlo code in the frame of the Eritr@C (European Riposte against Illicit TR@ffiCking) project. In the configurations analyzed the compliance with the dose limits for workers and the population stated by the European legislation is provided by appropriate shielding of the neutron sources and by the delimitation of a controlled area.

  15. Modulation index for VMAT considering both mechanical and dose calculation uncertainties.

    PubMed

    Park, Jong Min; Park, So-Yeon; Kim, Hyoungnyoun

    2015-09-21

    The aim of this study is to present a modulation index considering both mechanical and dose calculation uncertainties for volumetric modulated arc therapy (VMAT). As a modulation index considering only mechanical uncertainty of VMAT, MIt has been previously suggested. In this study, we developed a weighting factor which represents dose calculation uncertainty based on the aperture shapes of fluence maps at every control point of VMAT plans. In order to calculate the weighting factor, the thinning algorithm of image processing techniques was applied to measure field aperture irregularity. By combining this weighting factor with the previously suggested modulation index, MIt, comprehensive modulation index (MIc) was designed. To evaluate the performance of MIc, gamma passing rates, differences in mechanical parameters between plans and log files and differences in dose-volume parameters between plans and the plans reconstructed from log files were acquired with a total of 52 VMAT plans. Spearman's correlation coefficients (rs) between the values of MIc and measures of VMAT delivery accuracy were calculated. The rs values of MIc (f = 0.5) to global gamma passing rates with 2%/2 mm, 1%/2 mm and 2%/1 mm were  -0.728,-0.847 and  -0.617, respectively (p  <  0.001). Those to local gamma passing rates were  -0.765,-0.767 and  -0.748, respectively (p  <  0.001). The rs values of MIc (f = 0.5) to multi-leaf collimator and gantry angle errors were 0.800 and  -0.712, respectively (p  <  0.001). The MIc (f = 0.5) showed a total of 20 rs values (p  <  0.05) to the differences in dose-volumetric parameters from a total of 35 tested cases. The MIc (f = 0.5) demonstrated considerable power to predict VMAT delivery accuracy showing strong correlations to various measures of VMAT delivery accuracy. PMID:26317697

  16. Modulation index for VMAT considering both mechanical and dose calculation uncertainties

    NASA Astrophysics Data System (ADS)

    Park, Jong Min; Park, So-Yeon; Kim, Hyoungnyoun

    2015-09-01

    The aim of this study is to present a modulation index considering both mechanical and dose calculation uncertainties for volumetric modulated arc therapy (VMAT). As a modulation index considering only mechanical uncertainty of VMAT, MIt has been previously suggested. In this study, we developed a weighting factor which represents dose calculation uncertainty based on the aperture shapes of fluence maps at every control point of VMAT plans. In order to calculate the weighting factor, the thinning algorithm of image processing techniques was applied to measure field aperture irregularity. By combining this weighting factor with the previously suggested modulation index, MIt, comprehensive modulation index (MIc) was designed. To evaluate the performance of MIc, gamma passing rates, differences in mechanical parameters between plans and log files and differences in dose-volume parameters between plans and the plans reconstructed from log files were acquired with a total of 52 VMAT plans. Spearman’s correlation coefficients (rs) between the values of MIc and measures of VMAT delivery accuracy were calculated. The rs values of MIc (f = 0.5) to global gamma passing rates with 2%/2 mm, 1%/2 mm and 2%/1 mm were  -0.728,-0.847 and  -0.617, respectively (p  <  0.001). Those to local gamma passing rates were  -0.765,-0.767 and  -0.748, respectively (p  <  0.001). The rs values of MIc (f = 0.5) to multi-leaf collimator and gantry angle errors were 0.800 and  -0.712, respectively (p  <  0.001). The MIc (f = 0.5) showed a total of 20 rs values (p  <  0.05) to the differences in dose-volumetric parameters from a total of 35 tested cases. The MIc (f = 0.5) demonstrated considerable power to predict VMAT delivery accuracy showing strong correlations to various measures of VMAT delivery accuracy.

  17. Dose Measurements of Bremsstrahlung-Produced Neutrons at the Advanced Photon Source

    SciTech Connect

    Job, P.K.; Pisharody, M.; Semones, E.

    1998-08-01

    a few of such neutron flux measurements were conducted at high photon energies. Monte Carlo codes and analytical formulas are used to calculate the differential photon track length in targets. Together with the known photoneutron cross sections, the neutron yields are then determined as a function of incident electron energy. Neutron fluence calculated from these yields assumes isotropic emission of neutrons from a point source target. Because neutron transport is not handled in most of these studies, possible neutron interactions inside the target are not accounted for in calculating the energy and intensity outside the target. There is also the uncertainty of photoneutron production cross section at higher energies. A simultaneous measurement of bremsstrahlung and corresponding photoneutron production will provide photoneutron dose rates as a function of bremsstrahlung energy or power. Along with our already existing bremsstrahlung spectrum measurement expertise, we conducted simultaneous photoneutron dose measurements at the APS from thick targets of Fe, Cu, W, and Pb that are placed in the bremsstrahlung beam inside the FOE of the insertion device beamlines. An Andersson-Braun (AB) remmeter that houses a BF{sub 3} detector, as well as a very sensitive pressurized {sup 3}He detector, is used for neutron dose measurements. The dose equivalent rates, normalized to bremsstrahlung power, beam current, and storage ring vacuum, are measured for various targets. This report details the experimental setup, data acquisition system, calibration procedures, analysis of the data and the results of the measurements.

  18. A trichrome beam model for biological dose calculation in scanned carbon-ion radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Inaniwa, T.; Kanematsu, N.

    2015-01-01

    In scanned carbon-ion (C-ion) radiotherapy, some primary C-ions undergo nuclear reactions before reaching the target and the resulting particles deliver doses to regions at a significant distance from the central axis of the beam. The effects of these particles on physical dose distribution are accounted for in treatment planning by representing the transverse profile of the scanned C-ion beam as the superposition of three Gaussian distributions. In the calculation of biological dose distribution, however, the radiation quality of the scanned C-ion beam has been assumed to be uniform over its cross-section, taking the average value over the plane at a given depth (monochrome model). Since these particles, which have relatively low radiation quality, spread widely compared to the primary C-ions, the radiation quality of the beam should vary with radial distance from the central beam axis. To represent its transverse distribution, we propose a trichrome beam model in which primary C-ions, heavy fragments with atomic number Z ≥ 3, and light fragments with Z ≤ 2 are assigned to the first, second, and third Gaussian components, respectively. Assuming a realistic beam-delivery system, we performed computer simulations using Geant4 Monte Carlo code for analytical beam modeling of the monochrome and trichrome models. The analytical beam models were integrated into a treatment planning system for scanned C-ion radiotherapy. A target volume of 20  ×  20  ×  40 mm3 was defined within a water phantom. A uniform biological dose of 2.65 Gy (RBE) was planned for the target with the two beam models based on the microdosimetric kinetic model (MKM). The plans were recalculated with Geant4, and the recalculated biological dose distributions were compared with the planned distributions. The mean target dose of the recalculated distribution with the monochrome model was 2.72 Gy (RBE), while the dose with the trichrome model was 2.64 Gy (RBE). The monochrome model

  19. Application of GEANT4 radiation transport toolkit to dose calculations in anthropomorphic phantoms.

    PubMed

    Rodrigues, P; Trindade, A; Peralta, L; Alves, C; Chaves, A; Lopes, M C

    2004-12-01

    In this paper, we present a novel implementation of a dose calculation application, based on the GEANT4 Monte Carlo toolkit. Validation studies were performed with an homogeneous water phantom and an Alderson-Rando anthropomorphic phantom both irradiated with high-energy photon beams produced by a clinical linear accelerator. As input, this tool requires computer tomography images for automatic codification of voxel-based geometries and phase-space distributions to characterize the incident radiation field. Simulation results were compared with ionization chamber, thermoluminescent dosimetry data and commercial treatment planning system calculations. In homogeneous water phantom, overall agreement with measurements were within 1-2%. For anthropomorphic simulated setups (thorax and head irradiation) mean differences between GEANT4 and TLD measurements were less than 2%. Significant differences between GEANT4 and a semi-analytical algorithm implemented in the treatment planning system, were found in low-density regions, such as air cavities with strong electronic disequilibrium. PMID:15388147

  20. Waste Isolation Pilot Plant Title I operator dose calculations. Final report, LATA report No. 90

    SciTech Connect

    Hughes, P.S.; Rigdon, L.D.

    1980-02-01

    The radiation exposure dose was estimated for the Waste Isolation Pilot Plant (WIPP) operating personnel who do the unloading and transporting of the transuranic contact-handled waste. Estimates of the radiation source terms for typical TRU contact-handled waste were based on known composition and properties of the waste. The operations sequence for waste movement and storage in the repository was based upon the WIPP Title I data package. Previous calculations had been based on Conceptual Design Report data. A time and motion sequence was developed for personnel performing the waste handling operations both above and below ground. Radiation exposure calculations were then performed in several fixed geometries and folded with the time and motion studies for individual workers in order to determine worker exposure on an annual basis.

  1. Calculation of electron Dose Point Kernel in water with GEANT4 for medical application

    NASA Astrophysics Data System (ADS)

    Guimarães, C. C.; Moralles, M.; Sene, F. F.; Martinelli, J. R.; Okuno, E.

    2009-06-01

    The rapid insertion of new technologies in medical physics in the last years, especially in nuclear medicine, has been followed by a great development of faster Monte Carlo algorithms. GEANT4 is a Monte Carlo toolkit that contains the tools to simulate the problems of particle transport through matter. In this work, GEANT4 was used to calculate the dose-point-kernel (DPK) for monoenergetic electrons in water, which is an important reference medium for nuclear medicine. The three different physical models of electromagnetic interactions provided by GEANT4—Low Energy, Penelope and Standard—were employed. To verify the adequacy of these models, the results were compared with references from the literature. For all energies and physical models, the agreement between calculated DPKs and reported values is satisfactory.

  2. Calculation of Dose for Skyshine Radiation From a 45 MeV Electron LINAC

    NASA Astrophysics Data System (ADS)

    Hori, M.; Hikoji, M.; Takahashi, H.; Takahashi, K.; Kitaichi, M.; Sawamura, S.; Nojiri, I.

    1996-11-01

    Dose estimation for skyshine plays an important role in the evaluation of the environment around nuclear facilities. We performed calculations for the skyshine radiation from a Hokkaido University 45 MeV linear accelerator using a general purpose user's version of the EGS4 Monte Carlo Code. To verify accuracy of the code, the simulation results have been compared with our experimental results, in which a gated counting method was used to measure low-level pulsed leakage radiation. In experiment, measurements were carried out up to 600 m away from the LINAC. The simulation results are consistent with the experimental values at the distance between 100 and 400 m from the LINAC. However, agreements of both results up to 100 m from the LINAC are not as good because of the simplification of geometrical modeling in the simulation. It could be said that it is useful to apply this version to the calculation for skyshine.

  3. A model of the circulating blood for use in radiation dose calculations

    SciTech Connect

    Hui, T.E.; Poston, J.W. Sr.

    1987-01-01

    Over the last few years there has been a significant increase in the use of radionuclides in leukocyte, platelet, and erythrocyte imaging procedures. Radiopharmaceutical used in these procedures are confined primarily to the blood, have short half-lives, and irradiate the body as they move through the circulatory system. There is a need for a model, to describe the circulatory system in an adult human, which can be used to provide radiation absorbed dose estimates for these procedures. A simplified model has been designed assuming a static circulatory system and including major organs of the body. The model has been incorporated into the MIRD phantom and calculations have been completed for a number of exposure situations and radionuclides of clinical importance. The model will be discussed in detail and results of calculations using this model will be presented.

  4. A model of the circulating blood for use in radiation dose calculations

    SciTech Connect

    Hui, T.E.; Poston, J.W. Sr.

    1987-12-31

    Over the last few years there has been a significant increase in the use of radionuclides in leukocyte, platelet, and erythrocyte imaging procedures. Radiopharmaceutical used in these procedures are confined primarily to the blood, have short half-lives, and irradiate the body as they move through the circulatory system. There is a need for a model, to describe the circulatory system in an adult human, which can be used to provide radiation absorbed dose estimates for these procedures. A simplified model has been designed assuming a static circulatory system and including major organs of the body. The model has been incorporated into the MIRD phantom and calculations have been completed for a number of exposure situations and radionuclides of clinical importance. The model will be discussed in detail and results of calculations using this model will be presented.

  5. SU-E-T-626: Accuracy of Dose Calculation Algorithms in MultiPlan Treatment Planning System in Presence of Heterogeneities

    SciTech Connect

    Moignier, C; Huet, C; Barraux, V; Loiseau, C; Sebe-Mercier, K; Batalla, A; Makovicka, L

    2014-06-15

    Purpose: Advanced stereotactic radiotherapy (SRT) treatments require accurate dose calculation for treatment planning especially for treatment sites involving heterogeneous patient anatomy. The purpose of this study was to evaluate the accuracy of dose calculation algorithms, Raytracing and Monte Carlo (MC), implemented in the MultiPlan treatment planning system (TPS) in presence of heterogeneities. Methods: First, the LINAC of a CyberKnife radiotherapy facility was modeled with the PENELOPE MC code. A protocol for the measurement of dose distributions with EBT3 films was established and validated thanks to comparison between experimental dose distributions and calculated dose distributions obtained with MultiPlan Raytracing and MC algorithms as well as with the PENELOPE MC model for treatments planned with the homogenous Easycube phantom. Finally, bones and lungs inserts were used to set up a heterogeneous Easycube phantom. Treatment plans with the 10, 7.5 or the 5 mm field sizes were generated in Multiplan TPS with different tumor localizations (in the lung and at the lung/bone/soft tissue interface). Experimental dose distributions were compared to the PENELOPE MC and Multiplan calculations using the gamma index method. Results: Regarding the experiment in the homogenous phantom, 100% of the points passed for the 3%/3mm tolerance criteria. These criteria include the global error of the method (CT-scan resolution, EBT3 dosimetry, LINAC positionning …), and were used afterwards to estimate the accuracy of the MultiPlan algorithms in heterogeneous media. Comparison of the dose distributions obtained in the heterogeneous phantom is in progress. Conclusion: This work has led to the development of numerical and experimental dosimetric tools for small beam dosimetry. Raytracing and MC algorithms implemented in MultiPlan TPS were evaluated in heterogeneous media.

  6. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.

    PubMed

    Renner, F; Wulff, J; Kapsch, R-P; Zink, K

    2015-10-01

    There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as

  7. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

    NASA Astrophysics Data System (ADS)

    Renner, F.; Wulff, J.; Kapsch, R.-P.; Zink, K.

    2015-10-01

    There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as

  8. On the dosimetric behaviour of photon dose calculation algorithms in the presence of simple geometric heterogeneities: comparison with Monte Carlo calculations

    NASA Astrophysics Data System (ADS)

    Fogliata, Antonella; Vanetti, Eugenio; Albers, Dirk; Brink, Carsten; Clivio, Alessandro; Knöös, Tommy; Nicolini, Giorgia; Cozzi, Luca

    2007-03-01

    A comparative study was performed to reveal differences and relative figures of merit of seven different calculation algorithms for photon beams when applied to inhomogeneous media. The following algorithms were investigated: Varian Eclipse: the anisotropic analytical algorithm, and the pencil beam with modified Batho correction; Nucletron Helax-TMS: the collapsed cone and the pencil beam with equivalent path length correction; CMS XiO: the multigrid superposition and the fast Fourier transform convolution; Philips Pinnacle: the collapsed cone. Monte Carlo simulations (MC) performed with the EGSnrc codes BEAMnrc and DOSxyznrc from NRCC in Ottawa were used as a benchmark. The study was carried out in simple geometrical water phantoms (ρ = 1.00 g cm-3) with inserts of different densities simulating light lung tissue (ρ = 0.035 g cm-3), normal lung (ρ = 0.20 g cm-3) and cortical bone tissue (ρ = 1.80 g cm-3). Experiments were performed for low- and high-energy photon beams (6 and 15 MV) and for square (13 × 13 cm2) and elongated rectangular (2.8 × 13 cm2) fields. Analysis was carried out on the basis of depth dose curves and transverse profiles at several depths. Assuming the MC data as reference, γ index analysis was carried out distinguishing between regions inside the non-water inserts or inside the uniform water. For this study, a distance to agreement was set to 3 mm while the dose difference varied from 2% to 10%. In general all algorithms based on pencil-beam convolutions showed a systematic deficiency in managing the presence of heterogeneous media. In contrast, complicated patterns were observed for the advanced algorithms with significant discrepancies observed between algorithms in the lighter materials (ρ = 0.035 g cm-3), enhanced for the most energetic beam. For denser, and more clinical, densities a better agreement among the sophisticated algorithms with respect to MC was observed.

  9. Photon fluence-to-effective dose conversion coefficients calculated from a Saudi population-based phantom

    NASA Astrophysics Data System (ADS)

    Ma, A. K.; Altaher, K.; Hussein, M. A.; Amer, M.; Farid, K. Y.; Alghamdi, A. A.

    2014-02-01

    In this work we will present a new set of photon fluence-to-effective dose conversion coefficients using the Saudi population-based voxel phantom developed recently by our group. The phantom corresponds to an average Saudi male of 173 cm tall weighing 77 kg. There are over 125 million voxels in the phantom each of which is 1.37×1.37×1.00 mm3. Of the 27 organs and tissues of radiological interest specified in the recommendations of ICRP Publication 103, all but the oral mucosa, extrathoracic tissue and the lymph nodes were identified in the current version of the phantom. The bone surface (endosteum) is too thin to be identifiable; it is about 10 μm thick. The dose to the endosteum was therefore approximated by the dose to the bones. Irradiation geometries included anterior-posterior (AP), left (LLAT) and rotational (ROT). The simulations were carried out with the MCNPX code version 2.5.0. The fluence in free air and the energy depositions in each organ were calculated for monoenergetic photon beams from 10 keV to 10 MeV to obtain the conversion coefficients. The radiation and tissue weighting factors were taken from ICRP Publication 60 and 103. The results from this study will also be compared with the conversion coefficients in ICRP Publication 116.

  10. Voxel modeling of rabbits for use in radiological dose rate calculations.

    PubMed

    Caffrey, E A; Johansen, M P; Higley, K A

    2016-01-01

    Radiation dose to biota is generally calculated using Monte Carlo simulations of whole body ellipsoids with homogeneously distributed radioactivity throughout. More complex anatomical phantoms, termed voxel phantoms, have been developed to test the validity of these simplistic geometric models. In most voxel models created to date, human tissue composition and density values have been used in lieu of biologically accurate values for non-human biota. This has raised questions regarding variable tissue composition and density effects on the fraction of radioactive emission energy absorbed within tissues (e.g. the absorbed fraction - AF), along with implications for age-dependent dose rates as organisms mature. The results of this study on rabbits indicates that the variation in composition between two mammalian tissue types (e.g. human vs rabbit bones) made little difference in self-AF (SAF) values (within 5% over most energy ranges). However, variable tissue density (e.g. bone vs liver) can significantly impact SAF values. An examination of differences across life-stages revealed increasing SAF with testis and ovary size of over an order of magnitude for photons and several factors for electrons, indicating the potential for increasing dose rates to these sensitive organs as animals mature. AFs for electron energies of 0.1, 0.2, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0, and 4.0 MeV and photon energies of 0.01, 0.015, 0.02, 0.03, 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, and 4.0 MeV are provided for eleven rabbit tissues. The data presented in this study can be used to calculate accurate organ dose rates for rabbits and other small rodents; to aide in extending dose results among different mammal species; and to validate the use of ellipsoidal models for regulatory purposes. PMID:25971772

  11. Effect of elemental compositions on Monte Carlo dose calculations in proton therapy of eye tumors

    NASA Astrophysics Data System (ADS)

    Rasouli, Fatemeh S.; Farhad Masoudi, S.; Keshazare, Shiva; Jette, David

    2015-12-01

    Recent studies in eye plaque brachytherapy have found considerable differences between the dosimetric results by using a water phantom, and a complete human eye model. Since the eye continues to be simulated as water-equivalent tissue in the proton therapy literature, a similar study for investigating such a difference in treating eye tumors by protons is indispensable. The present study inquires into this effect in proton therapy utilizing Monte Carlo simulations. A three-dimensional eye model with elemental compositions is simulated and used to examine the dose deposition to the phantom. The beam is planned to pass through a designed beam line to moderate the protons to the desired energies for ocular treatments. The results are compared with similar irradiation to a water phantom, as well as to a material with uniform density throughout the whole volume. Spread-out Bragg peaks (SOBPs) are created by adding pristine peaks to cover a typical tumor volume. Moreover, the corresponding beam parameters recommended by the ICRU are calculated, and the isodose curves are computed. The results show that the maximum dose deposited in ocular media is approximately 5-7% more than in the water phantom, and about 1-1.5% less than in the homogenized material of density 1.05 g cm-3. Furthermore, there is about a 0.2 mm shift in the Bragg peak due to the tissue composition difference between the models. It is found that using the weighted dose profiles optimized in a water phantom for the realistic eye model leads to a small disturbance of the SOBP plateau dose. In spite of the plaque brachytherapy results for treatment of eye tumors, it is found that the differences between the simplified models presented in this work, especially the phantom containing the homogenized material, are not clinically significant in proton therapy. Taking into account the intrinsic uncertainty of the patient dose calculation for protons, and practical problems corresponding to applying patient

  12. Adaptation of GEANT4 to Monte Carlo dose calculations based on CT data.

    PubMed

    Jiang, H; Paganetti, H

    2004-10-01

    The GEANT4 Monte Carlo code provides many powerful functions for conducting particle transport simulations with great reliability and flexibility. However, as a general purpose Monte Carlo code, not all the functions were specifically designed and fully optimized for applications in radiation therapy. One of the primary issues is the computational efficiency, which is especially critical when patient CT data have to be imported into the simulation model. In this paper we summarize the relevant aspects of the GEANT4 tracking and geometry algorithms and introduce our work on using the code to conduct dose calculations based on CT data. The emphasis is focused on modifications of the GEANT4 source code to meet the requirements for fast dose calculations. The major features include a quick voxel search algorithm, fast volume optimization, and the dynamic assignment of material density. These features are ready to be used for tracking the primary types of particles employed in radiation therapy such as photons, electrons, and heavy charged particles. Recalculation of a proton therapy treatment plan generated by a commercial treatment planning program for a paranasal sinus case is presented as an example. PMID:15543788

  13. Calculated depth-dose distributions for H + and He + beams in liquid water

    NASA Astrophysics Data System (ADS)

    Garcia-Molina, Rafael; Abril, Isabel; Denton, Cristian D.; Heredia-Avalos, Santiago; Kyriakou, Ioanna; Emfietzoglou, Dimitris

    2009-08-01

    We have calculated the dose distribution delivered by proton and helium beams in liquid water as a function of the target-depth, for incident energies in the range 0.5-10 MeV/u. The motion of the projectiles through the stopping medium is simulated by a code that combines Monte Carlo and a finite differences algorithm to consider the electronic stopping power, evaluated in the dielectric framework, and the multiple nuclear scattering with the target nuclei. Changes in projectile charge-state are taken into account dynamically as it moves through the target. We use the MELF-GOS model to describe the energy loss function of liquid water, obtaining a value of 79.4 eV for its mean excitation energy. Our calculated stopping powers and depth-dose distributions are compared with those obtained using other methods to describe the energy loss function of liquid water, such as the extended Drude and the Penn models, as well as with the prediction of the SRIM code and the tables of ICRU.

  14. Gamma Dose Calculations in the Target Service Cell of the SNS

    SciTech Connect

    Azmy, Y.Y.; Johnson, J.O.; Lillie, R.A.; Santoro, R.T.

    1999-11-14

    Calculations of the gamma dose rates inside and outside of the Target Service Cell (TSC) of the Spallation Neutron Source (SNS) are complicated by the large size of the structure, large volume of air (internal void), optical thickness of the enclosing walls, and multiplicity of radiation sources. Furthermore, a reasonably detailed distribution of the dose rate over the volume of the TSC, and on the outside of its walls is necessary in order to optimize electronic instrument locations, and plan access control. For all these reasons a deterministic transport method was preferred over Monte Carlo, The three- dimensional neutral particle transport code TORT was employed for this purpose with support from other peripheral codes in the Discrete Ordinates of Oak Ridge System (DOORS). The computational model for the TSC is described and the features of TORT and its companion codes that enable such a difficult calculation are discussed. Most prominent is the presence of severe ray effects in the air cavity of the TSC that persists in the transport through the concrete walls and is pronounced throughout the problem volume. Initial attempts at eliminating ray effects from the computed results using the newly developed three-dimensional uncollided flux and first collided source code GRTUNCL3D are described.

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

    NASA Astrophysics Data System (ADS)

    Dobrzyńska, Magdalena

    2015-09-01

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

  16. A Comparison of Model Calculation and Measurement of Absorbed Dose for Proton Irradiation. Chapter 5

    NASA Technical Reports Server (NTRS)

    Zapp, N.; Semones, E.; Saganti, P.; Cucinotta, F.

    2003-01-01

    With the increase in the amount of time spent EVA that is necessary to complete the construction and subsequent maintenance of ISS, it will become increasingly important for ground support personnel to accurately characterize the radiation exposures incurred by EVA crewmembers. Since exposure measurements cannot be taken within the organs of interest, it is necessary to estimate these exposures by calculation. To validate the methods and tools used to develop these estimates, it is necessary to model experiments performed in a controlled environment. This work is such an effort. A human phantom was outfitted with detector equipment and then placed in American EMU and Orlan-M EVA space suits. The suited phantom was irradiated at the LLUPTF with proton beams of known energies. Absorbed dose measurements were made by the spaceflight operational dosimetrist from JSC at multiple sites in the skin, eye, brain, stomach, and small intestine locations in the phantom. These exposures are then modeled using the BRYNTRN radiation transport code developed at the NASA Langley Research Center, and the CAM (computerized anatomical male) human geometry model of Billings and Yucker. Comparisons of absorbed dose calculations with measurements show excellent agreement. This suggests that there is reason to be confident in the ability of both the transport code and the human body model to estimate proton exposure in ground-based laboratory experiments.

  17. A 3D pencil-beam-based superposition algorithm for photon dose calculation in heterogeneous media

    NASA Astrophysics Data System (ADS)

    Tillikainen, L.; Helminen, H.; Torsti, T.; Siljamäki, S.; Alakuijala, J.; Pyyry, J.; Ulmer, W.

    2008-07-01

    In this work, a novel three-dimensional superposition algorithm for photon dose calculation is presented. The dose calculation is performed as a superposition of pencil beams, which are modified based on tissue electron densities. The pencil beams have been derived from Monte Carlo simulations, and are separated into lateral and depth-directed components. The lateral component is modeled using exponential functions, which allows accurate modeling of lateral scatter in heterogeneous tissues. The depth-directed component represents the total energy deposited on each plane, which is spread out using the lateral scatter functions. Finally, convolution in the depth direction is applied to account for tissue interface effects. The method can be used with the previously introduced multiple-source model for clinical settings. The method was compared against Monte Carlo simulations in several phantoms including lung- and bone-type heterogeneities. Comparisons were made for several field sizes for 6 and 18 MV energies. The deviations were generally within (2%, 2 mm) of the field central axis dmax. Significantly larger deviations (up to 8%) were found only for the smallest field in the lung slab phantom for 18 MV. The presented method was found to be accurate in a wide range of conditions making it suitable for clinical planning purposes.

  18. 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.

  19. Validation of calculation algorithms for organ doses in CT by measurements on a 5 year old paediatric phantom.

    PubMed

    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. PMID:27192093

  20. A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs

    SciTech Connect

    Rodrigues, Anna; Yin, Fang-Fang; Wu, Qiuwen; Sawkey, Daren

    2015-05-15

    Purpose: To develop a framework for accurate electron Monte Carlo dose calculation. In this study, comprehensive validations of vendor provided electron beam phase space files for Varian TrueBeam Linacs against measurement data are presented. Methods: In this framework, the Monte Carlo generated phase space files were provided by the vendor and used as input to the downstream plan-specific simulations including jaws, electron applicators, and water phantom computed in the EGSnrc environment. The phase space files were generated based on open field commissioning data. A subset of electron energies of 6, 9, 12, 16, and 20 MeV and open and collimated field sizes 3 × 3, 4 × 4, 5 × 5, 6 × 6, 10 × 10, 15 × 15, 20 × 20, and 25 × 25 cm{sup 2} were evaluated. Measurements acquired with a CC13 cylindrical ionization chamber and electron diode detector and simulations from this framework were compared for a water phantom geometry. The evaluation metrics include percent depth dose, orthogonal and diagonal profiles at depths R{sub 100}, R{sub 50}, R{sub p}, and R{sub p+} for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors. Results: Agreement for the percent depth dose and orthogonal profiles between measurement and Monte Carlo was generally within 2% or 1 mm. The largest discrepancies were observed within depths of 5 mm from phantom surface. Differences in field size, penumbra, and flatness for the orthogonal profiles at depths R{sub 100}, R{sub 50}, and R{sub p} were within 1 mm, 1 mm, and 2%, respectively. Orthogonal profiles at SSDs of 100 and 120 cm showed the same level of agreement. Cone and cut-out output factors agreed well with maximum differences within 2.5% for 6 MeV and 1% for all other energies. Cone output factors at extended SSDs of 105, 110, 115, and 120 cm exhibited similar levels of agreement. Conclusions: We have presented a Monte Carlo simulation framework for electron beam dose calculations for

  1. Solubility of hot fuel particles from Chernobyl--influencing parameters for individual radiation dose calculations.

    PubMed

    Garger, Evgenii K; Meisenberg, Oliver; Odintsov, Oleksiy; Shynkarenko, Viktor; Tschiersch, Jochen

    2013-10-15

    Nuclear fuel particles of Chernobyl origin are carriers of increased radioactivity (hot particles) and are still present in the atmosphere of the Chernobyl exclusion zone. Workers in the zone may inhale these particles, which makes assessment necessary. The residence time in the lungs and the transfer in the blood of the inhaled radionuclides are crucial for inhalation dose assessment. Therefore, the dissolution of several kinds of nuclear fuel particles from air filters sampled in the Chernobyl exclusion zone was studied. For this purpose filter fragments with hot particles were submersed in simulated lung fluids (SLFs). The activities of the radionuclides (137)Cs, (90)Sr, (239+240)Pu and (241)Am were measured in the SLF and in the residuum of the fragments by radiometric methods after chemical treatment. Soluble fractions as well as dissolution rates of the nuclides were determined. The influence of the genesis of the hot particles, represented by the (137)Cs/(239+240)Pu ratio, on the availability of (137)Cs was demonstrated, whereas the dissolution of (90)Sr, (239+240)Pu and (241)Am proved to be independent of genesis. No difference in the dissolution of (137)Cs and (239+240)Pu was observed for the two applied types of SLF. Increased solubility was found for smaller hot particles. A two-component exponential model was used to describe the dissolution of the nuclides as a function of time. The results were applied for determining individual inhalation dose coefficients for the workers at the Chernobyl construction site. Greater dose coefficients for the respiratory tract and smaller coefficients for the other organs were calculated (compared to ICRP default values). The effective doses were in general lower for the considered radionuclides, for (241)Am even by one order of magnitude. PMID:24054559

  2. A hybrid approach for rapid, accurate, and direct kilovoltage radiation dose calculations in CT voxel space

    SciTech Connect

    Kouznetsov, Alexei; Tambasco, Mauro

    2011-03-15

    Purpose: To develop and validate a fast and accurate method that uses computed tomography (CT) voxel data to estimate absorbed radiation dose at a point of interest (POI) or series of POIs from a kilovoltage (kV) imaging procedure. Methods: The authors developed an approach that computes absorbed radiation dose at a POI by numerically evaluating the linear Boltzmann transport equation (LBTE) using a combination of deterministic and Monte Carlo (MC) techniques. This hybrid approach accounts for material heterogeneity with a level of accuracy comparable to the general MC algorithms. Also, the dose at a POI is computed within seconds using the Intel Core i7 CPU 920 2.67 GHz quad core architecture, and the calculations are performed using CT voxel data, making it flexible and feasible for clinical applications. To validate the method, the authors constructed and acquired a CT scan of a heterogeneous block phantom consisting of a succession of slab densities: Tissue (1.29 cm), bone (2.42 cm), lung (4.84 cm), bone (1.37 cm), and tissue (4.84 cm). Using the hybrid transport method, the authors computed the absorbed doses at a set of points along the central axis and x direction of the phantom for an isotropic 125 kVp photon spectral point source located along the central axis 92.7 cm above the phantom surface. The accuracy of the results was compared to those computed with MCNP, which was cross-validated with EGSnrc, and served as the benchmark for validation. Results: The error in the depth dose ranged from -1.45% to +1.39% with a mean and standard deviation of -0.12% and 0.66%, respectively. The error in the x profile ranged from -1.3% to +0.9%, with standard deviations of -0.3% and 0.5%, respectively. The number of photons required to achieve these results was 1x10{sup 6}. Conclusions: The voxel-based hybrid method evaluates the LBTE rapidly and accurately to estimate the absorbed x-ray dose at any POI or series of POIs from a kV imaging procedure.

  3. Calculs Monte Carlo en transport d'energie pour le calcul de la dose en radiotherapie sur plateforme graphique hautement parallele

    NASA Astrophysics Data System (ADS)

    Hissoiny, Sami

    Dose calculation is a central part of treatment planning. The dose calculation must be 1) accurate so that the medical physicists and the radio-oncologists can make a decision based on results close to reality and 2) fast enough to allow a routine use of dose calculation. The compromise between these two factors in opposition gave way to the creation of several dose calculation algorithms, from the most approximate and fast to the most accurate and slow. The most accurate of these algorithms is the Monte Carlo method, since it is based on basic physical principles. Since 2007, a new computing platform gains popularity in the scientific computing community: the graphics processor unit (GPU). The hardware platform exists since before 2007 and certain scientific computations were already carried out on the GPU. Year 2007, on the other hand, marks the arrival of the CUDA programming language which makes it possible to disregard graphic contexts to program the GPU. The GPU is a massively parallel computing platform and is adapted to data parallel algorithms. This thesis aims at knowing how to maximize the use of a graphics processing unit (GPU) to speed up the execution of a Monte Carlo simulation for radiotherapy dose calculation. To answer this question, the GPUMCD platform was developed. GPUMCD implements the simulation of a coupled photon-electron Monte Carlo simulation and is carried out completely on the GPU. The first objective of this thesis is to evaluate this method for a calculation in external radiotherapy. Simple monoenergetic sources and phantoms in layers are used. A comparison with the EGSnrc platform and DPM is carried out. GPUMCD is within a gamma criteria of 2%-2mm against EGSnrc while being at least 1200x faster than EGSnrc and 250x faster than DPM. The second objective consists in the evaluation of the platform for brachytherapy calculation. Complex sources based on the geometry and the energy spectrum of real sources are used inside a TG-43

  4. Characterization of differences in calculated and actual measured skin doses to canine limbs during stereotactic radiosurgery using Gafchromic film

    SciTech Connect

    Walters, Jerri; Ryan, Stewart; Harmon, Joseph F.

    2012-07-01

    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 this 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

  5. [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. PMID:26292419

  6. Calculation of indoor effective dose factors in ORNL phantoms series due to natural radioactivity in building materials.

    PubMed

    Krstic, D; Nikezic, D

    2009-10-01

    In this paper the effective dose in the age-dependent ORNL phantoms series, due to naturally occurring radionuclides in building materials, was calculated. The absorbed doses for various organs or human tissues have been calculated. The MCNP-4B computer code was used for this purpose. The effective dose was calculated according to ICRP Publication 74. The obtained values of dose conversion factors for a standard room are: 1.033, 0.752 and 0.0538 nSv h-1 per Bq kg-1 for elements of the U and Th decay series and for the K isotope, respectively. The values of effective dose agreed generally with those found in the literature, although the values estimated here for elements of the U series were higher in some cases. PMID:19741358

  7. An anatomically realistic lung model for Monte Carlo-based dose calculations

    SciTech Connect

    Liang Liang; Larsen, Edward W.; Chetty, Indrin J.

    2007-03-15

    Treatment planning for disease sites with large variations of electron density in neighboring tissues requires an accurate description of the geometry. This self-evident statement is especially true for the lung, a highly complex organ having structures with a wide range of sizes that range from about 10{sup -4} to 1 cm. In treatment planning, the lung is commonly modeled by a voxelized geometry obtained using computed tomography (CT) data at various resolutions. The simplest such model, which is often used for QA and validation work, is the atomic mix or mean density model, in which the entire lung is homogenized and given a mean (volume-averaged) density. The purpose of this paper is (i) to describe a new heterogeneous random lung model, which is based on morphological data of the human lung, and (ii) use this model to assess the differences in dose calculations between an actual lung (as represented by our model) and a mean density (homogenized) lung. Eventually, we plan to use the random lung model to assess the accuracy of CT-based treatment plans of the lung. For this paper, we have used Monte Carlo methods to make accurate comparisons between dose calculations for the random lung model and the mean density model. For four realizations of the random lung model, we used a single photon beam, with two different energies (6 and 18 MV) and four field sizes (1x1, 5x5, 10x10, and 20x20 cm{sup 2}). We found a maximum difference of 34% of D{sub max} with the 1x1, 18 MV beam along the central axis (CAX). A ''shadow'' region distal to the lung, with dose reduction up to 7% of D{sub max}, exists for the same realization. The dose perturbations decrease for larger field sizes, but the magnitude of the differences in the shadow region is nearly independent of the field size. We also observe that, compared to the mean density model, the random structures inside the heterogeneous lung can alter the shape of the isodose lines, leading to a broadening or shrinking of the

  8. Comparisons of Monte Carlo calculations with absorbed dose determinations in flat materials using high-current, energetic electron beams

    NASA Astrophysics Data System (ADS)

    Cleland, Marshall R.; Galloway, Richard A.; Heiss, Arthur H.; Logar, John R.

    2007-08-01

    International standards and guidelines for calibrating high-dose dosimetry systems to be used in industrial radiation processing recommend that dose-rate effects on dosimeters be evaluated under conditions of use. This is important when the irradiation relies on high-current electron accelerators, which usually provide very high dose-rates. However, most dosimeter calibration facilities use low-intensity gamma radiation or low-current electron accelerators, which deliver comparatively low dose-rates. Because of issues of thermal conductivity and response, portable calorimeters cannot be practically used with high-current accelerators, where product conveyor speeds under an electron beam can exceed several meters per second and the calorimeter is not suitable for use with product handling systems. As an alternative, Monte Carlo calculations can give theoretical estimates of the absorbed dose in materials with flat or complex configurations such that the results are independent of dose-rate. Monte Carlo results can then be compared to experimental dose determinations to see whether dose-rate effects in the dosimeters are significant. A Monte Carlo code has been used in this study to calculate the absorbed doses in alanine film dosimeters supported by flat sheets of plywood irradiated with electrons using incident energies extending from 1.0 MeV to 10 MeV with beam currents up to 30 mA. The same process conditions have been used for dose determinations with high-current electron beams using low dose-rate gamma calibrated alanine film dosimeters. The close agreement between these calculations and the dosimeter determinations indicates that the response of this type of dosimeter system is independent of the dose-rate, and provides assurance that Monte Carlo calculations can yield results with sufficient accuracy for many industrial applications.

  9. 42 CFR 82.18 - How will NIOSH calculate internal dose to the primary cancer site(s)?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... primary cancer site(s)? 82.18 Section 82.18 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND... Dose Reconstruction Process § 82.18 How will NIOSH calculate internal dose to the primary cancer site(s... cancer covered by a claim is in a tissue not covered by existing ICRP models, NIOSH will use the...

  10. 42 CFR 82.18 - How will NIOSH calculate internal dose to the primary cancer site(s)?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... primary cancer site(s)? 82.18 Section 82.18 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND... Dose Reconstruction Process § 82.18 How will NIOSH calculate internal dose to the primary cancer site(s... cancer covered by a claim is in a tissue not covered by existing ICRP models, NIOSH will use the...

  11. 42 CFR 82.18 - How will NIOSH calculate internal dose to the primary cancer site(s)?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... primary cancer site(s)? 82.18 Section 82.18 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND... Dose Reconstruction Process § 82.18 How will NIOSH calculate internal dose to the primary cancer site(s... cancer covered by a claim is in a tissue not covered by existing ICRP models, NIOSH will use the...

  12. 42 CFR 82.18 - How will NIOSH calculate internal dose to the primary cancer site(s)?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... primary cancer site(s)? 82.18 Section 82.18 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND... Dose Reconstruction Process § 82.18 How will NIOSH calculate internal dose to the primary cancer site(s... cancer covered by a claim is in a tissue not covered by existing ICRP models, NIOSH will use the...

  13. 42 CFR 82.18 - How will NIOSH calculate internal dose to the primary cancer site(s)?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... primary cancer site(s)? 82.18 Section 82.18 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND... Dose Reconstruction Process § 82.18 How will NIOSH calculate internal dose to the primary cancer site(s... cancer covered by a claim is in a tissue not covered by existing ICRP models, NIOSH will use the...

  14. Offsite radiation doses from Hanford Operations for the years 1983 through 1987: A comparison of results calculated by two methods

    SciTech Connect

    Soldat, J.K.

    1989-10-01

    This report compares the results of the calculation of potential radiation doses to the public by two different environmental dosimetric systems for the years 1983 through 1987. Both systems project the environmental movement of radionuclides released with effluents from Hanford operations; their concentrations in air, water, and foods; the intake of radionuclides by ingestion and inhalation; and, finally, the potential radiation doses from radionuclides deposited in the body and from external sources. The first system, in use for the past decade at Hanford, calculates radiation doses in terms of 50-year cumulative dose equivalents to body organs and to the whole body, based on the methodology defined in ICRP Publication 2. This system uses a suite of three computer codes: PABLM, DACRIN, and KRONIC. In the new system, 50-year committed doses are calculated in accordance with the recommendations of the ICRP Publications 26 and 30, which were adopted by the US Department of Energy (DOE) in 1985. This new system calculates dose equivalent (DE) to individual organs and effective dose equivalent (EDE). The EDE is a risk-weighted DE that is designed to be an indicator of the potential health effects arising from the radiation dose. 16 refs., 1 fig., 38 tabs.

  15. Significant impact on effective doses received during commercial flights calculated using the new ICRP radiation weighting factors.

    PubMed

    Chen, Jing; Mares, Vladimir

    2010-01-01

    This note discusses the significant impact on effective doses received during commercial flights calculated using the new International Commission on Radiological Protection (ICRP) radiation weighting factors. It also provides an update on adult effective doses given in a previous article in Health Physics when the old ICRP radiation weighting factors were used. PMID:19959953

  16. Calculated organ doses from selected prostate treatment plans using Monte Carlo simulations and an anatomically realistic computational phantom

    NASA Astrophysics Data System (ADS)

    Bednarz, Bryan; Hancox, Cindy; Xu, X. George

    2009-09-01

    There is growing concern about radiation-induced second cancers associated with radiation treatments. Particular attention has been focused on the risk to patients treated with intensity-modulated radiation therapy (IMRT) due primarily to increased monitor units. To address this concern we have combined a detailed medical linear accelerator model of the Varian Clinac 2100 C with anatomically realistic computational phantoms to calculate organ doses from selected treatment plans. This paper describes the application to calculate organ-averaged equivalent doses using a computational phantom for three different treatments of prostate cancer: a 4-field box treatment, the same box treatment plus a 6-field 3D-CRT boost treatment and a 7-field IMRT treatment. The equivalent doses per MU to those organs that have shown a predilection for second cancers were compared between the different treatment techniques. In addition, the dependence of photon and neutron equivalent doses on gantry angle and energy was investigated. The results indicate that the box treatment plus 6-field boost delivered the highest intermediate- and low-level photon doses per treatment MU to the patient primarily due to the elevated patient scatter contribution as a result of an increase in integral dose delivered by this treatment. In most organs the contribution of neutron dose to the total equivalent dose for the 3D-CRT treatments was less than the contribution of photon dose, except for the lung, esophagus, thyroid and brain. The total equivalent dose per MU to each organ was calculated by summing the photon and neutron dose contributions. For all organs non-adjacent to the primary beam, the equivalent doses per MU from the IMRT treatment were less than the doses from the 3D-CRT treatments. This is due to the increase in the integral dose and the added neutron dose to these organs from the 18 MV treatments. However, depending on the application technique and optimization used, the required MU

  17. Calculated organ doses from selected prostate treatment plans using Monte Carlo simulations and an anatomically realistic computational phantom

    PubMed Central

    Bednarz, Bryan; Hancox, Cindy; Xu, X George

    2012-01-01

    There is growing concern about radiation-induced second cancers associated with radiation treatments. Particular attention has been focused on the risk to patients treated with intensity-modulated radiation therapy (IMRT) due primarily to increased monitor units. To address this concern we have combined a detailed medical linear accelerator model of the Varian Clinac 2100 C with anatomically realistic computational phantoms to calculate organ doses from selected treatment plans. This paper describes the application to calculate organ-averaged equivalent doses using a computational phantom for three different treatments of prostate cancer: a 4-field box treatment, the same box treatment plus a 6-field 3D-CRT boost treatment and a 7-field IMRT treatment. The equivalent doses per MU to those organs that have shown a predilection for second cancers were compared between the different treatment techniques. In addition, the dependence of photon and neutron equivalent doses on gantry angle and energy was investigated. The results indicate that the box treatment plus 6-field boost delivered the highest intermediate- and low-level photon doses per treatment MU to the patient primarily due to the elevated patient scatter contribution as a result of an increase in integral dose delivered by this treatment. In most organs the contribution of neutron dose to the total equivalent dose for the 3D-CRT treatments was less than the contribution of photon dose, except for the lung, esophagus, thyroid and brain. The total equivalent dose per MU to each organ was calculated by summing the photon and neutron dose contributions. For all organs non-adjacent to the primary beam, the equivalent doses per MU from the IMRT treatment were less than the doses from the 3D-CRT treatments. This is due to the increase in the integral dose and the added neutron dose to these organs from the 18 MV treatments. However, depending on the application technique and optimization used, the required MU

  18. SPENVIS Implementation of End-of-Life Solar Cell Calculations Using the Displacement Damage Dose Methodology

    NASA Technical Reports Server (NTRS)

    Walters, Robert; Summers, Geoffrey P.; Warmer. Keffreu J/; Messenger, Scott; Lorentzen, Justin R.; Morton, Thomas; Taylor, Stephen J.; Evans, Hugh; Heynderickx, Daniel; Lei, Fan

    2007-01-01

    This paper presents a method for using the SPENVIS on-line computational suite to implement the displacement damage dose (D(sub d)) methodology for calculating end-of-life (EOL) solar cell performance for a specific space mission. This paper builds on our previous work that has validated the D(sub d) methodology against both measured space data [1,2] and calculations performed using the equivalent fluence methodology developed by NASA JPL [3]. For several years, the space solar community has considered general implementation of the D(sub d) method, but no computer program exists to enable this implementation. In a collaborative effort, NRL, NASA and OAI have produced the Solar Array Verification and Analysis Tool (SAVANT) under NASA funding, but this program has not progressed beyond the beta-stage [4]. The SPENVIS suite with the Multi Layered Shielding Simulation Software (MULASSIS) contains all of the necessary components to implement the Dd methodology in a format complementary to that of SAVANT [5]. NRL is currently working with ESA and BIRA to include the Dd method of solar cell EOL calculations as an integral part of SPENVIS. This paper describes how this can be accomplished.

  19. [Evaluation tests of computer systems concerning tri-dimensional dose calculations].

    PubMed

    Simonian-Sauve, M; Smart, C

    1998-01-01

    The development of irradiation techniques in radiotherapy shows a clear tendency towards the systematic use of three-dimensional (3D) information. Great efforts are being made to set up 3D conformal radiotherapy. Consequently, in the aim of greater coherence and accuracy, "the dosimetric tool" must also meet the requirements of 3D radiotherapy, as it plays a role in the treatment chain. To know if the treatment planning system is a "3D", "2D" or even "1D" system, one should not be satisfied with reading the technical documentation and the program algorithm description nor entirely trust the constructor's assertions. It is essential to clearly and precisely evaluate the possibilities of the treatment planning system. Even if it is proved not to satisfy perfectly all the tests which would qualify it as a real 3D calculation system, the study of the test results helps to give clear explanations of the dosimetric results. Two series of test cases are proposed. The first series allows us to understand in which conditions the treatment planning system takes into account the scatter influence in a volume. The second series is designed to inform us about the capability of the dose calculation algorithm when the medium encloses non-homogeneities. These test cases do not constitute an exhaustive "check-list" able to tackle completely the question of 3D calculation. They are submitted as examples and should be considered as an evaluation methodology for the software implanted in the treatment planning system. PMID:9749097

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

    SciTech Connect

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

    2012-02-15

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

  1. Dose calculation for hypofractionated volumetric-modulated arc therapy: approximating continuous arc delivery and tongue-and-groove modeling*

    PubMed Central

    Yang, Jie; Tang, Grace; Zhang, Pengpeng; Hunt, Margie; Lim, Seng B.; LoSasso, Thomas; Mageras, Gig

    2016-01-01

    Hypofractionated treatments generally increase the complexity of a treatment plan due to the more stringent constraints of normal tissues and target coverage. As a result, treatment plans contain more modulated MLC motions that may require extra efforts for accurate dose calculation. This study explores methods to minimize the differences between in-house dose calculation and actual delivery of hypofractionated volumetric-modulated arc therapy (VMAT), by focusing on arc approximation and tongue-and-groove (TG) modeling. For dose calculation, the continuous delivery arc is typically approximated by a series of static beams with an angular spacing of 2°. This causes significant error when there is large MLC movement from one beam to the next. While increasing the number of beams will minimize the dose error, calculation time will increase significantly. We propose a solution by inserting two additional apertures at each of the beam angle for dose calculation. These additional apertures were interpolated at two-thirds’ degree before and after each beam. Effectively, there were a total of three MLC apertures at each beam angle, and the weighted average fluence from the three apertures was used for calculation. Because the number of beams was kept the same, calculation time was only increased by about 6%–8%. For a lung plan, areas of high local dose differences (> 4%) between film measurement and calculation with one aperture were significantly reduced in calculation with three apertures. Ion chamber measurement also showed similar results, where improvements were seen with calculations using additional apertures. Dose calculation accuracy was further improved for TG modeling by developing a sampling method for beam fluence matrix. Single element point sampling for fluence transmitted through MLC was used for our fluence matrix with 1 mm resolution. For Varian HDMLC, grid alignment can cause fluence sampling error. To correct this, transmission volume averaging was

  2. Dose calculation for hypofractionated volumetric-modulated arc therapy: approximating continuous arc delivery and tongue-and-groove modeling.

    PubMed

    Yang, Jie; Tang, Grace; Zhang, Pengpeng; Hunt, Margie; Lim, Seng B; LoSasso, Thomas; Mageras, Gig

    2016-01-01

     Hypofractionated treatments generally increase the complexity of a treatment plan due to the more stringent constraints of normal tissues and target coverage. As a result, treatment plans contain more modulated MLC motions that may require extra efforts for accurate dose calculation. This study explores methods to minimize the differences between in-house dose calculation and actual delivery of hypofractionated volumetric-modulated arc therapy (VMAT), by focusing on arc approximation and tongue-and-groove (TG) modeling. For dose calculation, the continuous delivery arc is typically approximated by a series of static beams with an angular spacing of 2°. This causes significant error when there is large MLC movement from one beam to the next. While increasing the number of beams will minimize the dose error, calculation time will increase significantly. We propose a solution by inserting two additional apertures at each of the beam angle for dose calculation. These additional apertures were interpolated at two-thirds' degree before and after each beam. Effectively, there were a total of three MLC apertures at each beam angle, and the weighted average fluence from the three apertures was used for calculation. Because the number of beams was kept the same, calculation time was only increased by about 6%-8%. For a lung plan, areas of high local dose differences (> 4%) between film measurement and calculation with one aperture were significantly reduced in calculation with three apertures. Ion chamber measure-ment also showed similar results, where improvements were seen with calculations using additional apertures. Dose calculation accuracy was further improved for TG modeling by developing a sampling method for beam fluence matrix. Single ele-ment point sampling for fluence transmitted through MLC was used for our fluence matrix with 1 mm resolution. For Varian HDMLC, grid alignment can cause fluence sampling error. To correct this, transmission volume averaging was

  3. Dose calculations using MARS for Bremsstrahlung beam stops and collimators in APS beamline stations.

    SciTech Connect

    Dooling, J.; Accelerator Systems Division

    2010-11-01

    The Monte Carlo radiation transport code MARS is used to model the generation of gas bremsstrahlung (GB) radiation from 7-GeV electrons which scatter from residual gas atoms in undulator straight sections within the Advanced Photon Source (APS) storage ring. Additionally, MARS is employed to model the interactions of the GB radiation with components along the x-ray beamlines and then determine the expected radiation dose-rates that result. In this manner, MARS can be used to assess the adequacy of existing shielding or the specifications for new shielding when required. The GB radiation generated in the 'thin-target' of an ID straight section will consist only of photons in a 1/E-distribution up to the full energy of the stored electron beam. Using this analytical model, the predicted GB power for a typical APS 15.38-m insertion device (ID) straight section is 4.59 x 10{sup -7} W/nTorr/mA, assuming a background gas composed of air (Z{sub eff} = 7.31) at room temperature (293K). The total GB power provides a useful benchmark for comparisons between analytical and numerical approaches. We find good agreement between MARS and analytical estimates for total GB power. The extended straight section 'target' creates a radial profile of GB, which is highly peaked centered on the electron beam. The GB distribution reflects the size of the electron beam that creates the radiation. Optimizing the performance of MARS in terms of CPU time per incident trajectory requires the use of a relatively short, high-density gas target (air); in this report, the target density is {rho}L = 2.89 x 10{sup -2} g/cm{sup 2} over a length of 24 cm. MARS results are compared with the contact dose levels reported in TB-20, which used EGS4 for radiation transport simulations. Maximum dose-rates in 1 cc of tissue phantom form the initial basis for comparison. MARS and EGS4 results are approximately the same for maximum 1-cc dose-rates and attenuation in the photon-dominated regions; for thicker

  4. 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.

  5. Offsite dose calculation manual guidance: Standard radiological effluent controls for pressurized water reactors

    SciTech Connect

    Meinke, W.W.; Essig, T.H.

    1991-04-01

    This report contains guidance which may be voluntarily used by licensees who choose to implement the provision of Generic Letter 89-01, which allows Radiological Effect Technical Specifications (RETS) to be removed from the main body of the Technical Specifications and placed in the Offsite Dose Calculation Manual (ODCM). Guidance is provided for Standard Effluent Controls definitions, Controls for effluent monitoring instrumentation, Controls for effluent releases, Controls for radiological environmental monitoring, and the basis for Controls. Guidance on the formulation of RETS has been available in draft from (NUREG-0471 and -0473) for a number of years; the current effort simply recasts those RETS into Standard Radiological Effluent Controls for application to the ODCM. Also included for completeness are: (1) radiological environmental monitoring program guidance previously which had been available as a Branch Technical Position (Rev. 1, November 1979); (2) existing ODCM guidance; and (3) a reproduction of generic Letter 89-01.

  6. Code System to Calculate Radiation Dose Rates Relative to Spent Fuel Shipping Casks.

    1993-05-20

    Version 00 QBF calculates and plots in a short running time, three dimensional radiation dose rate distributions in the form of contour maps on specified planes resulting from cylindrical sources loaded into vehicles or ships. Shielding effects by steel walls and shielding material layers are taken into account in addition to the shadow effect among casks. This code system identifies the critical points on which to focus when designing the radiation shielding structure and wheremore » each of the spent fuel shipping casks should be stored. The code GRAPH reads the output data file of QBF and plots it using the HGX graphics library. QBF unifies the functions of the SMART and MANYCASK codes included in CCC-482.« less

  7. Tetrahedral-mesh-based computational human phantom for fast Monte Carlo dose calculations

    NASA Astrophysics Data System (ADS)

    Yeom, Yeon Soo; Jeong, Jong Hwi; Han, Min Cheol; Kim, Chan Hyeong

    2014-06-01

    Although polygonal-surface computational human phantoms can address several critical limitations of conventional voxel phantoms, their Monte Carlo simulation speeds are much slower than those of voxel phantoms. In this study, we sought to overcome this problem by developing a new type of computational human phantom, a tetrahedral mesh phantom, by converting a polygonal surface phantom to a tetrahedral mesh geometry. The constructed phantom was implemented in the Geant4 Monte Carlo code to calculate organ doses as well as to measure computation speed, the values were then compared with those for the original polygonal surface phantom. It was found that using the tetrahedral mesh phantom significantly improved the computation speed by factors of between 150 and 832 considering all of the particles and simulated energies other than the low-energy neutrons (0.01 and 1 MeV), for which the improvement was less significant (17.2 and 8.8 times, respectively).

  8. The development and application of the visible Chinese human model for Monte Carlo dose calculations.

    PubMed

    Zhang, Guozhi; Luo, Qingming; Zeng, Shaoqun; Liu, Qian

    2008-02-01

    A new whole-body computational phantom, the Visible Chinese Human (VCH), was developed using high-resolution transversal photographs of a Chinese adult male cadaver. Following the segmentation and tridimensional reconstruction, a voxel-based model that faithfully represented the average anatomical characteristics of the Chinese population was established for radia