BENCHMARKING UPGRADED HOTSPOT DOSE CALCULATIONS AGAINST MACCS2 RESULTS
Energy Technology Data Exchange (ETDEWEB)
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.
International Nuclear Information System (INIS)
In order to compare the internal effective dose evaluation in past and present, an automatic calculation sheet was developed using the parameters such as the dose conversion factors and intake of foods etc. in ICRP Pub.60, Pub72, the new 'Environmental Radiation Monitoring Guide' revised on March 29, 2001. It makes possible to sum up monitoring data in each year, to evaluate dose and to compare them to the past data. The equation, parameters of ingestion and inhalation, nuclides detected, subject nuclides, dose conversion factor of committed dose equivalent by ingestion and inhalation, fundamental principles, limits, model, monitoring results, calculation for estimation and valuation and discussion are described. This article must be handled with the utmost care on parameters, model, ND of monitoring results. (S.Y.)
Results of 1 year of clinical experience with independent dose calculation software for VMAT fields
Directory of Open Access Journals (Sweden)
Juan Fernando Mata Colodro
2014-01-01
Full Text Available It is widely accepted that a redundant independent dose calculation (RIDC must be included in any treatment planning verification procedure. Specifically, volumetric modulated arc therapy (VMAT technique implies a comprehensive quality assurance (QA program in which RIDC should be included. In this paper, the results obtained in 1 year of clinical experience are presented. Eclipse from Varian is the treatment planning system (TPS, here in use. RIDC were performed with the commercial software; Diamond ® (PTW which is capable of calculating VMAT fields. Once the plan is clinically accepted, it is exported via Digital Imaging and Communications in Medicine (DICOM to RIDC, together with the body contour, and then a point dose calculation is performed, usually at the isocenter. A total of 459 plans were evaluated. The total average deviation was -0.3 ± 1.8% (one standard deviation (1SD. For higher clearance the plans were grouped by location in: Prostate, pelvis, abdomen, chest, head and neck, brain, stereotactic radiosurgery, lung stereotactic body radiation therapy, and miscellaneous. The highest absolute deviation was -0.8 ± 1.5% corresponding to the prostate. A linear fit between doses calculated by RIDC and by TPS produced a correlation coefficient of 0.9991 and a slope of 1.0023. These results are very close to those obtained in the validation process. This agreement led us to consider this RIDC software as a valuable tool for QA in VMAT plans.
International Nuclear Information System (INIS)
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-hr. The advantages and disadvantages of the method are discussed. (authors)
Radioactive cloud dose calculations
International Nuclear Information System (INIS)
Radiological dosage principles, as well as methods for calculating external and internal dose rates, following dispersion and deposition of radioactive materials in the atmosphere are described. Emphasis has been placed on analytical solutions that are appropriate for hand calculations. In addition, the methods for calculating dose rates from ingestion are discussed. A brief description of several computer programs are included for information on radionuclides. There has been no attempt to be comprehensive, and only a sampling of programs has been selected to illustrate the variety available
International Nuclear Information System (INIS)
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
Verification of Internal Dose Calculations.
Aissi, Abdelmadjid
The MIRD internal dose calculations have been in use for more than 15 years, but their accuracy has always been questionable. There have been attempts to verify these calculations; however, these attempts had various shortcomings which kept the question of verification of the MIRD data still unanswered. The purpose of this research was to develop techniques and methods to verify the MIRD calculations in a more systematic and scientific manner. The research consisted of improving a volumetric dosimeter, developing molding techniques, and adapting the Monte Carlo computer code ALGAM to the experimental conditions and vice versa. The organic dosimetric system contained TLD-100 powder and could be shaped to represent human organs. The dosimeter possessed excellent characteristics for the measurement of internal absorbed doses, even in the case of the lungs. The molding techniques are inexpensive and were used in the fabrication of dosimetric and radioactive source organs. The adaptation of the computer program provided useful theoretical data with which the experimental measurements were compared. The experimental data and the theoretical calculations were compared for 6 source organ-7 target organ configurations. The results of the comparison indicated the existence of an agreement between measured and calculated absorbed doses, when taking into consideration the average uncertainty (16%) of the measurements, and the average coefficient of variation (10%) of the Monte Carlo calculations. However, analysis of the data gave also an indication that the Monte Carlo method might overestimate the internal absorbed doses. Even if the overestimate exists, at least it could be said that the use of the MIRD method in internal dosimetry was shown to lead to no unnecessary exposure to radiation that could be caused by underestimating the absorbed dose. The experimental and the theoretical data were also used to test the validity of the Reciprocity Theorem for heterogeneous
Prenatal radiation exposure. Dose calculation
International Nuclear Information System (INIS)
The unborn child requires special protection. In this context, the indication for an X-ray examination is to be checked critically. If thereupon radiation of the lower abdomen including the uterus cannot be avoided, the examination should be postponed until the end of pregnancy or alternative examination techniques should be considered. Under certain circumstances, either accidental or in unavoidable cases after a thorough risk assessment, radiation exposure of the unborn may take place. In some of these cases an expert radiation hygiene consultation may be required. This consultation should comprise the expected risks for the unborn while not perturbing the mother or the involved medical staff. For the risk assessment in case of an in-utero X-ray exposition deterministic damages with a defined threshold dose are distinguished from stochastic damages without a definable threshold dose. The occurrence of deterministic damages depends on the dose and the developmental stage of the unborn at the time of radiation. To calculate the risks of an in-utero radiation exposure a three-stage concept is commonly applied. Depending on the amount of radiation, the radiation dose is either estimated, roughly calculated using standard tables or, in critical cases, accurately calculated based on the individual event. The complexity of the calculation thereby increases from stage to stage. An estimation based on stage one is easily feasible whereas calculations based on stages two and especially three are more complex and often necessitate execution by specialists. This article demonstrates in detail the risks for the unborn child pertaining to its developmental phase and explains the three-stage concept as an evaluation scheme. It should be noted, that all risk estimations are subject to considerable uncertainties.
Equivalent-spherical-shield neutron dose calculations
International Nuclear Information System (INIS)
Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab
International Nuclear Information System (INIS)
The results of a previous study giving fecal and urinary excretion curves of five radioelements (cesium 137, cobalt 60, cerium 144, strontium 90, and plutonium 239) after radioactive aerosol inhalation by a man were interpreted. It is tried to draw conclusions on the validity of the theoretical parameters needed for calculating the load and the dose in man
Radiological Dose Calculations for Fusion Facilities
Energy Technology Data Exchange (ETDEWEB)
Michael L. Abbott; Lee C. Cadwallader; David A. Petti
2003-04-01
This report summarizes the results and rationale for radiological dose calculations for the maximally exposed individual during fusion accident conditions. Early doses per unit activity (Sieverts per TeraBecquerel) are given for 535 magnetic fusion isotopes of interest for several release scenarios. These data can be used for accident assessment calculations to determine if the accident consequences exceed Nuclear Regulatory Commission and Department of Energy evaluation guides. A generalized yearly dose estimate for routine releases, based on 1 Terabecquerel unit releases per radionuclide, has also been performed using averaged site parameters and assumed populations. These routine release data are useful for assessing designs against US Environmental Protection Agency yearly release limits.
International Nuclear Information System (INIS)
In this report, we calculated radioactivity concentration of radionuclides potentially contained in low level radioactive waste (LLW) generated from research, medical, and industrial facilities corresponding to dose criterion (10 μSv/y) for near surface disposal. From the result we discussed radionuclides whose radioactivity in the waste should be evaluated. Many kinds of radionuclides are contained in LLW generated from research facilities because of various uses of radioactive materials in the facilities. 220 kinds of nuclides whose half-life are more than 30 days were selected considering the possibility of existence in LLW generated from research facilities. Radioactivity concentrations corresponding to dose criterion of 40 nuclides among 220 ones were calculated by using the representative model in Japan because the concentrations of 40 nuclides had not been calculated yet. As a result, the radioactivity concentrations of 21 nuclides were evaluated, however, the concentrations of 19 ones were invalid values that are larger than the specific radioactivity of nuclides. Skyshine dose from each nuclide among 19 nuclides during operation of disposal facility was calculated. Skyshine dose from each of 11 nuclides among 19 ones was relatively high, therefore, 11 ones were selected as nuclides to be considered in safety assessment of operation period. Consequently, we got radioactivity concentrations of 141 nuclides corresponding to dose criterion among 220 ones. As a result the 141 nuclides were selected as the nuclides for evaluation of radioactivity in waste. And then we added 31 nuclides except for 141 ones as the nuclides to be evaluated in safety assessment of operation period. The radioactivity concentrations set in this report can be used as criteria of categorization of LLW between trench type and concrete vault type disposal and of preliminary selection of important nuclides of these disposals in the generic conditions. (author)
Calculational Tool for Skin Contamination Dose Assessment
Hill, R L
2002-01-01
Spreadsheet calculational tool was developed to automate the calculations preformed for dose assessment of skin contamination. This document reports on the design and testing of the spreadsheet calculational tool.
Calculation of external dose from distributed source
International Nuclear Information System (INIS)
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
Dose calculations for intakes of ore dust
Energy Technology Data Exchange (ETDEWEB)
O`Brien, R.S
1998-08-01
This report describes a methodology for calculating the committed effective dose for mixtures of radionuclides, such as those which occur in natural radioactive ores and dusts. The formulae are derived from first principles, with the use of reasonable assumptions concerning the nature and behaviour of the radionuclide mixtures. The calculations are complicated because these `ores` contain a range of particle sizes, have different degrees of solubility in blood and other body fluids, and also have different biokinetic clearance characteristics from the organs and tissues in the body. The naturally occurring radionuclides also tend to occur in series, i.e. one is produced by the radioactive decay of another `parent` radionuclide. The formulae derived here can be used, in conjunction with a model such as LUDEP, for calculating total dose resulting from inhalation and/or ingestion of a mixture of radionuclides, and also for deriving annual limits on intake and derived air concentrations for these mixtures. 15 refs., 14 tabs., 3 figs.
Methods of bone marrow dose calculation
International Nuclear Information System (INIS)
Several methods of bone marrow dose calculation for photon irradiation were analised. After a critical analysis, the author proposes the adoption, by the Instituto de Radioprotecao e Dosimetria/CNEN, of Rosenstein's method for dose calculations in Radiodiagnostic examinations and Kramer's method in case of occupational irradiation. It was verified by Eckerman and Simpson that for monoenergetic gamma emitters uniformly distributed within the bone mineral of the skeleton the dose in the bone surface can be several times higher than dose in skeleton. In this way, is also proposed the Calculation of tissue-air ratios for bone surfaces in some irradiation geometries and photon energies to be included in the Rosenstein's method for organ dose calculation in Radiodiagnostic examinations. (Author)
Phantoms for calculations of absorbed organ dose
International Nuclear Information System (INIS)
We have developed a computer code IDES (Internal Dose Estimation System). In this code, MIRD Transformation Method is used and photon simulation by Monte Carlo method is also possible. We have studied Japanese phantoms in two procedures, mathematical phantom and 'symbol phantoms'. Our mathematical phantoms realize their height and body weights but does not hold some of organ weights, which were measured by TANAKA and KAWAMURA. The symbol phantom can solve this discrepancy and realize a realistic phantom, although it remains problems of authorization and normalization. Errors were estimated for internal dose calculations and it was pointed out that to use realistic organ weights and parameters of kinetics was important competitively to reduce uncertainty of the results. (author)
Study of dose calculation on breast brachytherapy using prism TPS
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.
Study of dose calculation on breast brachytherapy using prism TPS
International Nuclear Information System (INIS)
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
Agriculture-related radiation dose calculations
International Nuclear Information System (INIS)
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
Agriculture-related radiation dose calculations
Energy Technology Data Exchange (ETDEWEB)
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.
Fast dose calculation in magnetic fields with GPUMCD
Energy Technology Data Exchange (ETDEWEB)
Hissoiny, S; Ozell, B [Ecole Polytechnique de Montreal, Departement de genie informatique et genie logiciel, 2500 Chemin de Polytechnique, Montreal, Quebec H3T 1J4 (Canada); Raaijmakers, A J E; Raaymakers, B W [Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht (Netherlands); Despres, P, E-mail: sami.hissoiny@polymtl.ca [Departement de physique, Universite Laval, Quebec (Canada)
2011-08-21
A new hybrid imaging-treatment modality, the MRI-Linac, involves the irradiation of the patient in the presence of a strong magnetic field. This field acts on the charged particles, responsible for depositing dose, through the Lorentz force. These conditions require a dose calculation engine capable of taking into consideration the effect of the magnetic field on the dose distribution during the planning stage. Also in the case of a change in anatomy at the time of treatment, a fast online replanning tool is desirable. It is improbable that analytical solutions such as pencil beam calculations can be efficiently adapted for dose calculations within a magnetic field. Monte Carlo simulations have therefore been used for the computations but the calculation speed is generally too slow to allow online replanning. In this work, GPUMCD, a fast graphics processing unit (GPU)-based Monte Carlo dose calculation platform, was benchmarked with a new feature that allows dose calculations within a magnetic field. As a proof of concept, this new feature is validated against experimental measurements. GPUMCD was found to accurately reproduce experimental dose distributions according to a 2%-2 mm gamma analysis in two cases with large magnetic field-induced dose effects: a depth-dose phantom with an air cavity and a lateral-dose phantom surrounded by air. Furthermore, execution times of less than 15 s were achieved for one beam in a prostate case phantom for a 2% statistical uncertainty while less than 20 s were required for a seven-beam plan. These results indicate that GPUMCD is an interesting candidate, being fast and accurate, for dose calculations for the hybrid MRI-Linac modality.
Methodology of dose calculation for the SRS SAR
Energy Technology Data Exchange (ETDEWEB)
Price, J.B.
1991-07-01
The Savannah River Site (SRS) Safety Analysis Report (SAR) covering K reactor operation assesses a spectrum of design basis accidents. The assessment includes estimation of the dose consequences from the analyzed accidents. This report discusses the methodology used to perform the dose analysis reported in the SAR and also includes the quantified doses. Doses resulting from postulated design basis reactor accidents in Chapter 15 of the SAR are discussed, as well as an accident in which three percent of the fuel melts. Doses are reported for both atmospheric and aqueous releases. The methodology used to calculate doses from these accidents as reported in the SAR is consistent with NRC guidelines and industry standards. The doses from the design basis accidents for the SRS reactors are below the limits set for commercial reactors by the NRC and also meet industry criteria. A summary of doses for various postulated accidents is provided.
Study of dose calculation on breast brachytherapy using prism TPS
Energy Technology Data Exchange (ETDEWEB)
Fendriani, Yoza; Haryanto, Freddy [Nuclear Physics and Biophysics Research Division, FMIPA Institut Teknologi Bandung, Physics Buildings, Jl. Ganesha 10, Bandung 40132 (Indonesia)
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.
Quantification of Proton Dose Calculation Accuracy in the Lung
Energy Technology Data Exchange (ETDEWEB)
Grassberger, Clemens, E-mail: Grassberger.Clemens@mgh.harvard.edu [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Center for Proton Radiotherapy, Paul Scherrer Institute, Villigen (Switzerland); Daartz, Juliane; Dowdell, Stephen; Ruggieri, Thomas; Sharp, Greg; Paganetti, Harald [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States)
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.
The effect of dose calculation accuracy on inverse treatment planning
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.
Dose calculation and treatment planning for the Brookhaven NCT Facility
Energy Technology Data Exchange (ETDEWEB)
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.
Dose calculation and treatment planning for the Brookhaven NCT Facility
Energy Technology Data Exchange (ETDEWEB)
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.
Fast Electron Beam Simulation and Dose Calculation
Trindade, A; Peralta, L; Lopes, M C; Alves, C; Chaves, A
2003-01-01
A flexible multiple source model capable of fast reconstruction of clinical electron beams is presented in this paper. A source model considers multiple virtual sources emulating the effect of accelerator head components. A reference configuration (10 MeV and 10x10 cm2 field size) for a Siemens KD2 linear accelerator was simulated in full detail using GEANT3 Monte Carlo code. Our model allows the reconstruction of other beam energies and field sizes as well as other beam configurations for similar accelerators using only the reference beam data. Electron dose calculations were performed with the reconstructed beams in a water phantom and compared with experimental data. An agreement of 1-2% / 1-2 mm was obtained, equivalent to the accuracy of full Monte Carlo accelerator simulation. The source model reduces accelerator simulation CPU time by a factor of 7500 relative to full Monte Carlo approaches. The developed model was then interfaced with DPM, a fast radiation transport Monte Carlo code for dose calculati...
Comparison of dose calculation methods for brachytherapy of intraocular tumors
Energy Technology Data Exchange (ETDEWEB)
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 [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Quality MediPhys LLC, Denville, New Jersey 07834 (United States); New York Eye Cancer Center, New York, New York 10065 (United States); Department of Radiation Oncology, Comprehensive Cancer Center of Nevada, Las Vegas, Nevada 89169 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Radiation Physics, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030 (United States) and Department of Experimental Diagnostic Imaging, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Physics, Elekta Inc., Norcross, Georgia 30092 (United States); Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520 (United States)
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
Internal dose conversion factors for calculation of dose to the public
International Nuclear Information System (INIS)
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
Recommendations for Insulin Dose Calculator Risk Management
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
Monte Carlo dose calculation in dental amalgam phantom.
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
Monte Carlo dose calculation in dental amalgam phantom.
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.
Monte carlo dose calculation in dental amalgam phantom
Directory of Open Access Journals (Sweden)
Mohd Zahri Abdul Aziz
2015-01-01
Full Text Available 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.
A convolution-superposition dose calculation engine for GPUs
International Nuclear Information System (INIS)
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.
A convolution-superposition dose calculation engine for GPUs
Energy Technology Data Exchange (ETDEWEB)
Hissoiny, Sami; Ozell, Benoit; Despres, Philippe [Departement de genie informatique et genie logiciel, Ecole polytechnique de Montreal, 2500 Chemin de Polytechnique, Montreal, Quebec H3T 1J4 (Canada); Departement de radio-oncologie, CRCHUM-Centre hospitalier de l' Universite de Montreal, 1560 rue Sherbrooke Est, Montreal, Quebec H2L 4M1 (Canada)
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.
Dose Calculation Evolution for Internal Organ Irradiation in Humans
International Nuclear Information System (INIS)
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
DICOM organ dose does not accurately represent calculated dose in mammography
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; pAltman 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.
PRDC - A software package for personnel radiation dose calculation
International Nuclear Information System (INIS)
To determine effective dose, we usually need to use a very complicated human body model and a sophisticated computer code to transport radiations in the body model and surrounding medium, which is not very easy to practicing health physicists in the field. This study develops and tests a software package, called PRDC (Personnel Radiation Dose Calculation), which calculates effective dose and radiation doses to various organs/tissues and personal dosemeters based on a series of interpolations. (authors)
Monte Carlo calculation of ''skyshine'' neutron dose from ALS [Advanced Light Source
International Nuclear Information System (INIS)
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
Calculation of dose conversion factors for thoron decay products
Energy Technology Data Exchange (ETDEWEB)
Ishikawa, Tetsuo [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Tokonami, Shinji [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Nemeth, Csaba [Pannon University, 10 Egyetem St, 8201 Veszprem (Hungary)
2007-12-15
The dose conversion factors for short-lived thoron decay products were calculated using a dosimetric approach. The calculations were based on a computer program LUDEP, which implements the ICRP 66 respiratory tract model. The dose per equilibrium equivalent concentration for thoron (EETC) was calculated with respect to (1) equivalent dose to each region of the lung tissues (bronchial, bronchiolar and alveolar), (2) weighted equivalent dose to organs other than lung, and (3) effective dose. The calculations indicated that (1) the most exposed region of the lung tissues was the bronchial for the unattached fraction and the bronchiolar for the attached fraction, (2) the effective dose is dominated by the contribution of lung dose, and (3) the effective dose per EETC was about four times larger than the effective dose per equilibrium equivalent concentration for radon (EERC). The calculated dose conversion factors were applied to the comparative dosimetry for some thoron-enhanced areas where the EERC and EETC have been measured. In the case of a spa in Japan, the dose from thoron decay products was larger than the dose from radon decay products.
Calculation of dose conversion factors for thoron decay products.
Ishikawa, Tetsuo; Tokonami, Shinji; Nemeth, Csaba
2007-12-01
The dose conversion factors for short-lived thoron decay products were calculated using a dosimetric approach. The calculations were based on a computer program LUDEP, which implements the ICRP 66 respiratory tract model. The dose per equilibrium equivalent concentration for thoron (EETC) was calculated with respect to (1) equivalent dose to each region of the lung tissues (bronchial, bronchiolar and alveolar), (2) weighted equivalent dose to organs other than lung, and (3) effective dose. The calculations indicated that (1) the most exposed region of the lung tissues was the bronchial for the unattached fraction and the bronchiolar for the attached fraction, (2) the effective dose is dominated by the contribution of lung dose, and (3) the effective dose per EETC was about four times larger than the effective dose per equilibrium equivalent concentration for radon (EERC). The calculated dose conversion factors were applied to the comparative dosimetry for some thoron-enhanced areas where the EERC and EETC have been measured. In the case of a spa in Japan, the dose from thoron decay products was larger than the dose from radon decay products.
DICOM organ dose does not accurately represent calculated dose in mammography
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.
Comparison between calculation methods of dose rates in gynecologic brachytherapy
International Nuclear Information System (INIS)
In treatments with radiations for gynecologic tumors is necessary to evaluate the quality of the results obtained by different calculation methods for the dose rates on the points of clinical interest (A, rectal, vesicle). The present work compares the results obtained by two methods. The Manual Calibration Method (MCM) tri dimensional (Vianello E., et.al. 1998), using orthogonal radiographs for each patient in treatment, and the Theraplan/T P-11 planning system (Thratonics International Limited 1990) this last one verified experimentally (Vianello et.al. 1996). The results show that MCM can be used in the physical-clinical practice with a percentile difference comparable at the computerized programs. (Author)
Energy Technology Data Exchange (ETDEWEB)
Yan Guanghua [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Liu, Chihray; Lu Bo; Palta, Jatinder R; Li, Jonathan G [Department of Radiation Oncology, University of Florida, Gainesville, FL 32610-0385 (United States)
2008-04-21
The purpose of this study was to choose an appropriate head scatter source model for the fast and accurate independent planar dose calculation for intensity-modulated radiation therapy (IMRT) with MLC. The performance of three different head scatter source models regarding their ability to model head scatter and facilitate planar dose calculation was evaluated. A three-source model, a two-source model and a single-source model were compared in this study. In the planar dose calculation algorithm, in-air fluence distribution was derived from each of the head scatter source models while considering the combination of Jaw and MLC opening. Fluence perturbations due to tongue-and-groove effect, rounded leaf end and leaf transmission were taken into account explicitly. The dose distribution was calculated by convolving the in-air fluence distribution with an experimentally determined pencil-beam kernel. The results were compared with measurements using a diode array and passing rates with 2%/2 mm and 3%/3 mm criteria were reported. It was found that the two-source model achieved the best agreement on head scatter factor calculation. The three-source model and single-source model underestimated head scatter factors for certain symmetric rectangular fields and asymmetric fields, but similar good agreement could be achieved when monitor back scatter effect was incorporated explicitly. All the three source models resulted in comparable average passing rates (>97%) when the 3%/3 mm criterion was selected. The calculation with the single-source model and two-source model was slightly faster than the three-source model due to their simplicity.
International Nuclear Information System (INIS)
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
Source term calculations for assessing radiation dose to equipment
International Nuclear Information System (INIS)
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
Deterministic calculations of radiation doses from brachytherapy seeds
International Nuclear Information System (INIS)
Brachytherapy is used for treating certain types of cancer by inserting radioactive sources into tumours. CDTN/CNEN is developing brachytherapy seeds to be used mainly in prostate cancer treatment. Dose calculations play a very significant role in the characterization of the developed seeds. The current state-of-the-art of computation dosimetry relies on Monte Carlo methods using, for instance, MCNP codes. However, deterministic calculations have some advantages, as, for example, short computer time to find solutions. This paper presents a software developed to calculate doses in a two-dimensional space surrounding the seed, using a deterministic algorithm. The analysed seeds consist of capsules similar to IMC6711 (OncoSeed), that are commercially available. The exposure rates and absorbed doses are computed using the Sievert integral and the Meisberger third order polynomial, respectively. The software also allows the isodose visualization at the surface plan. The user can choose between four different radionuclides (192Ir, 198Au, 137Cs and 60Co). He also have to enter as input data: the exposure rate constant; the source activity; the active length of the source; the number of segments in which the source will be divided; the total source length; the source diameter; and the actual and effective source thickness. The computed results were benchmarked against results from literature and developed software will be used to support the characterization process of the source that is being developed at CDTN. The software was implemented using Borland Delphi in Windows environment and is an alternative to Monte Carlo based codes. (author)
Dose Rate Calculations for Rotary Mode Core Sampling Exhauster
Foust, D J
2000-01-01
This document provides the calculated estimated dose rates for three external locations on the Rotary Mode Core Sampling (RMCS) exhauster HEPA filter housing, per the request of Characterization Field Engineering.
Directory of Open Access Journals (Sweden)
Atsushi Komemushi
2012-01-01
Full Text Available Purpose. To assess differences in dose distribution of a vertebral body injected with bone cement as calculated by radiation treatment planning system (RTPS and actual dose distribution. Methods. We prepared two water-equivalent phantoms with cement, and the other two phantoms without cement. The bulk density of the bone cement was imported into RTPS to reduce error from high CT values. A dose distribution map for the phantoms with and without cement was calculated using RTPS with clinical setting and with the bulk density importing. Actual dose distribution was measured by the film density. Dose distribution as calculated by RTPS was compared to the dose distribution measured by the film dosimetry. Results. For the phantom with cement, dose distribution was distorted for the areas corresponding to inside the cement and on the ventral side of the cement. However, dose distribution based on film dosimetry was undistorted behind the cement and dose increases were seen inside cement and around the cement. With the equivalent phantom with bone cement, differences were seen between dose distribution calculated by RTPS and that measured by the film dosimetry. Conclusion. The dose distribution of an area containing bone cement calculated using RTPS differs from actual dose distribution.
Ability of medical students to calculate drug doses in children after their paediatric attachment
Directory of Open Access Journals (Sweden)
Oshikoya KA
2008-12-01
Full Text Available Dose calculation errors constitute a significant part of prescribing errors which might have resulted from informal teaching of the topic in medical schools. Objectives: To determine adequacy of knowledge and skills of drug dose calculations in children acquired by medical students during their clinical attachment in paediatrics.Methods: Fifty two 5th year medical students of the Lagos State University College of Medicine (LASUCOM, Ikeja were examined on drug dose calculations from a vial and ampoules of injections, syrup and suspension, and tablet formulation. The examination was with a structured questionnaire mostly in the form of multiple choice questions.Results: Thirty-six (69.2% and 30 (57.7% students were taught drug dose calculation in neonatal posting and during ward rounds/ bed-side teaching, respectively. Less than 50% of the students were able to calculate the correct doses of each of adrenaline, gentamicin, chloroquine and sodium bicarbonate injections required by the patient. Dose calculation was however relatively better with adrenalin when compared with the other injections. The proportion of female students that calculated the correct doses of quinine syrup and cefuroxime suspension were significantly higher than those of their male counterparts (p<0.05 and p<0.01, respectively; Chi-square test. When doses calculated in mg/dose and mL/dose was compared for adrenalin injection and each of quinine syrup and cefuroxime suspension, there were significant differences (adrenaline and quinine, p=0.005; adrenaline and cefuroxime, p=0.003: Fischer’s exact test. Dose calculation errors of similar magnitude to injections, syrup and suspension were also observed with tablet formulation.Conclusions: LASUCOM medical students lacked the basic knowledge of paediatric drug dose calculations but were willing to learn if the topic was formally taught. Drug dose calculations should be given a prominent consideration in the undergraduate medical
Widder, Joachim; Hollander, Miranda; Ubbels, Jan F.; Bolt, Rene A.; Langendijk, Johannes A.
2010-01-01
Purpose: To define a method of dose prescription employing Monte Carlo (MC) dose calculation in stereotactic body radiotherapy (SBRT) for lung tumours aiming at a dose as low as possible outside of the PTV. Methods and materials: Six typical T1 lung tumours - three small, three large - were construc
Measurements and calculations of doses from radioactive particles
International Nuclear Information System (INIS)
Three Mile Island (TMI) and Tchernobyl reactor accidents have revealed the importance of the skin exposure to beta radiation produced by small high activity sources, named 'hot particles'. In nuclear power reactors, they may arise as small fragments of irradiated fuel or material which have been neutron activated by passing through the reactor co. In recent years, skin exposure to hot particles has been subject to different limitation criteria, formulated by AIEA, ICRP, NCRP working groups. The present work is the contribution of CEA Grenoble to a contract of the Commission of the European communities in cooperation with several laboratories: University of Birmingham, University of Toulouse and University of Montpellier with the main goal to check experiments and calculations of tissue dose from 60Co radioactive particles. This report is split up into two parts: hot particle dosimetry close to a 60Co spherical sample with an approximately 200 μm diameter, using a PTW extrapolation chamber model 233991; dose calculations from two codes: the Varskin Mod 2 computer code and the Hot 25 S2 Monte Carlo algorithm. The two codes lead to similar results; nevertheless there is a large discrepancy (of about 2) between calculations and PTW measurements which are higher by a factor of 1.9. At a 70 μm skin depth and for 1 cm2 irradiated area, the total (β + γ) tissue dose rate delivered by a spherical ( φ = 200 μm) 60Co source, in contact with skin, is of the order of 6.1 10-2 nGy s-1 Bq-1. (author)
Dose-Response Calculator for ArcGIS
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.
Mathematical models for calculating radiation dose to the fetus
International Nuclear Information System (INIS)
Estimates of radiation dose from radionuclides inside the body are calculated on the basis of energy deposition in mathematical models representing the organs and tissues of the human body. Complex models may be used with radiation transport codes to calculate the fraction of emitted energy that is absorbed in a target tissue even at a distance from the source. Other models may be simple geometric shapes for which absorbed fractions of energy have already been calculated. Models of Reference Man, the 15-year-old (Reference Woman), the 10-year-old, the five-year-old, the one-year-old, and the newborn have been developed and used for calculating specific absorbed fractions (absorbed fractions of energy per unit mass) for several different photon energies and many different source-target combinations. The Reference woman model is adequate for calculating energy deposition in the uterus during the first few weeks of pregnancy. During the course of pregnancy, the embryo/fetus increases rapidly in size and thus requires several models for calculating absorbed fractions. In addition, the increases in size and changes in shape of the uterus and fetus result in the repositioning of the maternal organs and in different geometric relationships among the organs and the fetus. This is especially true of the excretory organs such as the urinary bladder and the various sections of the gastrointestinal tract. Several models have been developed for calculating absorbed fractions of energy in the fetus, including models of the uterus and fetus for each month of pregnancy and complete models of the pregnant woman at the end of each trimester. In this paper, the available models and the appropriate use of each will be discussed. (Author) 19 refs., 7 figs
Calculation of the dose caused by internal radiation
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-07-01
For the purposes of monitoring radiation exposure it is necessary to determine or to estimate the dose caused by both external and internal radiation. When comparing the value of exposure to the dose limits, account must be taken of the total dose incurred from different sources. This guide explains how to calculate the committed effective dose caused by internal radiation and gives the conversion factors required for the calculation. Application of the maximum values for radiation exposure is dealt with in ST guide 7.2, which also sets out the definitions of the quantities and concepts most commonly used in the monitoring of radiation exposure. The monitoring of exposure and recording of doses are dealt with in ST Guides 7.1 and 7.4.
Emergency Doses (ED) - Revision 3: A calculator code for environmental dose computations
International Nuclear Information System (INIS)
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
Neutron absorbed dose determination by calculations of recoil energy.
Wrobel, F; Benabdesselam, M; Iacconi, P; Lapraz, D
2004-01-01
The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy. PMID:15353750
Calculation method for gamma-dose rates from spherical puffs
International Nuclear Information System (INIS)
The Lagrangian puff-models are widely used for calculation of the dispersion of atmospheric releases. Basic output from such models are concentrations of material in the air and on the ground. The most simple method for calculation of the gamma dose from the concentration of airborne activity is based on semi-infinite cloud model. This method is however only applicable for points far away from the release point. The exact calculation of the cloud dose using the volume integral requires significant computer time. The volume integral for the gamma dose could be approximated by using the semi-infinite cloud model combined with correction factors. This type of calculation procedure is very fast, but usually the accuracy is poor due to the fact that the same correction factors are used for all isotopes. The authors describe a more elaborate correction method. This method uses precalculated values of the gamma-dose rate as a function of the puff dispersion parameter (δp) and the distance from the puff centre for four energy groups. The release of energy for each radionuclide in each energy group has been calculated and tabulated. Based on these tables and a suitable interpolation procedure the calculation of gamma doses takes very short time and is almost independent of the number of radionuclides. (au) (7 tabs., 7 ills., 12 refs.)
Assessing medical students’ competence in calculating drug doses
Directory of Open Access Journals (Sweden)
Catherine Harries
2013-09-01
Full Text Available Evidence suggests that healthcare professionals are not optimally able to calculate medicine doses and various strategies have been employed to improve these skills. In this study, the performance of third and fourth year medical students was assessed and the success of various educational interventions investigated. Students were given four types of dosing calculations typical of those required in an emergency setting. Full competence (at the 100% level was defined as correctly answering all four categories of calculation at any one time. Three categories correct meant competence at the 75% level. Interventions comprised an assignment with a model answer for self-assessment in the third year and a small group tutorial in the fourth year. The small groups provided opportunities for peer-assisted learning. A subgroup of 23 students received individual tuition from the lecturer prior to the start of the fourth year. Amongst the 364 eligible students, full competence rose from 23% at the beginning of the third year to 66% by the end of the fourth year. More students succeeded during the fourth than the third year of study. Success of small group tuition was assessed in a sample of 200 students who had formal assessments both before and after the fourth year tuition. Competence at the 75% level improved by 10% in attendees and decreased by 3% in non-attendees, providing evidence of the value of students receiving assistance from more able same-language peers. Good results were achieved with one-on-one tuition where individualised assistance allowed even struggling students to improve.
Development of a computational methodology for internal dose calculations
Yoriyaz, H
2000-01-01
A new approach for calculating internal dose estimates was developed through the use of a more realistic computational model of the human body and a more precise tool for the radiation transport simulation. The present technique shows the capability to build a patient-specific phantom with tomography data (a voxel-based phantom) for the simulation of radiation transport and energy deposition using Monte Carlo methods such as in the MCNP-4B code. In order to utilize the segmented human anatomy as a computational model for the simulation of radiation transport, an interface program, SCMS, was developed to build the geometric configurations for the phantom through the use of tomographic images. This procedure allows to calculate not only average dose values but also spatial distribution of dose in regions of interest. With the present methodology absorbed fractions for photons and electrons in various organs of the Zubal segmented phantom were calculated and compared to those reported for the mathematical phanto...
Impact of dose calculation algorithm on radiation therapy
Institute of Scientific and Technical Information of China (English)
Wen-Zhou; Chen; Ying; Xiao; Jun; Li
2014-01-01
The quality of radiation therapy depends on the ability to maximize the tumor control probability while minimizing 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.
The models of internal dose calculation in ICRP
International Nuclear Information System (INIS)
There are a lot discussions about internal dose calculation in ICRP. Many efforts are devoted to improvement in models and parameters. In this report, we discuss what kind of models and parameters are used in ICRP. Models are divided into two parts, the dosimetric model and biokinetic model. The former is a mathematical phantom model, and it is mainly developed in ORNL. The results are used in many researchers. The latter is a compartment model and it has a difficulty to decide the parameter values. They are not easy to estimate because of their age dependency. ICRP officially sets values at ages of 3 month, 1 year, 5 year, 10 year, 15 year and adult, and recommends to get values among ages by linear age interpolate. But it is very difficult to solve the basic equation with these values, so we calculate by use of computers. However, it has complex shame and needs long CPU time. We should make approximated equations. The parameter values include much uncertainty because of less experimental data, especially for a child. And these models and parameter values are for Caucasian. We should inquire whether they could correctly describe other than Caucasian. The body size affects the values of calculated SAF, and the differences of metabolism change the biokinetic pattern. (author)
Doses resulting from intrusion into uranium tailings areas
International Nuclear Information System (INIS)
In the future, it is conceivable that institutional controls of uranium tailings areas may cease to exist and individuals may intrude into these areas unaware of the potential radiation hazards. The objective of this study was to estimate the potential doses to the intruders for a comprehensive set of intrusion scenarios. Reference tailings areas in the Elliot Lake region of northern Ontario and in northern Saskatchewan were developed to the extent required to calculate radiation exposures. The intrusion scenarios for which dose calculations were performed, were categorized into the following classes: habitation of the tailings, agricultural activities, construction activities, and recreational activities. Realistic exposure conditions were specified and annual doses were calculated by applying standard dose conversion factors. The exposure estimates demonstrated that the annual doses resulting from recreational activities and from construction activities would be generally small, less than twenty millisieverts, while the habitational and agricultural activities could hypothetically result in doses of several hundred millisieverts. However, the probability of occurrence of these latter classes of scenarios is considered to be much lower than scenarios involving either construction or recreational activities
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
Energy Technology Data Exchange (ETDEWEB)
Munoz Cervantes, A.
2010-07-01
Estimates of the radiological consequences of accidents are part of the safety studies of a nuclear power plant. The criterion used today is the effective dose received by the public as a result of an accident. The country standards set a limit on that dose, and that value can vary significantly from one country to another, as seen in the second chapter of this paper.
Calculation of radiation dose rate arisen from radionuclide contained in building materials
International Nuclear Information System (INIS)
This paper presents some results that we used MCNP5 program to calculate radiation dose rate arisen from radionuclide in building materials. Since then, the limits of radionuclide content in building materials are discussed. The calculation results by MCNP are compared with those calculated by analytical method. (author)
Benchmarking analytical calculations of proton doses in heterogeneous matter.
Ciangaru, George; Polf, Jerimy C; Bues, Martin; Smith, Alfred R
2005-12-01
A proton dose computational algorithm, performing an analytical superposition of infinitely narrow proton beamlets (ASPB) is introduced. The algorithm uses the standard pencil beam technique of laterally distributing the central axis broad beam doses according to the Moliere scattering theory extended to slablike varying density media. The purpose of this study was to determine the accuracy of our computational tool by comparing it with experimental and Monte Carlo (MC) simulation data as benchmarks. In the tests, parallel wide beams of protons were scattered in water phantoms containing embedded air and bone materials with simple geometrical forms and spatial dimensions of a few centimeters. For homogeneous water and bone phantoms, the proton doses we calculated with the ASPB algorithm were found very comparable to experimental and MC data. For layered bone slab inhomogeneity in water, the comparison between our analytical calculation and the MC simulation showed reasonable agreement, even when the inhomogeneity was placed at the Bragg peak depth. There also was reasonable agreement for the parallelepiped bone block inhomogeneity placed at various depths, except for cases in which the bone was located in the region of the Bragg peak, when discrepancies were as large as more than 10%. When the inhomogeneity was in the form of abutting air-bone slabs, discrepancies of as much as 8% occurred in the lateral dose profiles on the air cavity side of the phantom. Additionally, the analytical depth-dose calculations disagreed with the MC calculations within 3% of the Bragg peak dose, at the entry and midway depths in the phantom. The distal depth-dose 20%-80% fall-off widths and ranges calculated with our algorithm and the MC simulation were generally within 0.1 cm of agreement. The analytical lateral-dose profile calculations showed smaller (by less than 0.1 cm) 20%-80% penumbra widths and shorter fall-off tails than did those calculated by the MC simulations. Overall
Considerations of beta and electron transport in internal dose calculations
International Nuclear Information System (INIS)
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 ampersand 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
Considerations of beta and electron transport in internal dose calculations
International Nuclear Information System (INIS)
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 ampersand 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
Considerations of beta and electron transport in internal dose calculations
Energy Technology Data Exchange (ETDEWEB)
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.
Monte Carlo dose calculation in dental amalgam phantom
Mohd Zahri Abdul Aziz; Yusoff, A. L.; N D Osman; R. Abdullah; Rabaie, N. A.; M S Salikin
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 treatm...
Energy Technology Data Exchange (ETDEWEB)
Vianello, Elizabeth A.; Almeida, Carlos E. de [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil); Biaggio, Maria F. de [Universidade do Estado, Rio de Janeiro, RJ (Brazil)
1998-09-01
This paper describes a manual method for dose calculation in brachytherapy of gynecological tumors, which allows the calculation of the doses at any plane or point of clinical interest. This method uses basic principles of vectorial algebra and the simulating orthogonal films taken from the patient with the applicators and dummy sources in place. The results obtained with method were compared with the values calculated with the values calculated with the treatment planning system model Theraplan and the agreement was better than 5% in most cases. The critical points associated with the final accuracy of the proposed method is related to the quality of the image and the appropriate selection of the magnification factors. This method is strongly recommended to the radiation oncology centers where are no treatment planning systems available and the dose calculations are manually done. (author) 10 refs., 5 figs.
A Monte Carlo dose calculation tool for radiotherapy treatment planning
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.
Tissue heterogeneity in IMRT dose calculation for lung cancer.
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
A simplified analytical random walk model for proton dose calculation
Yao, Weiguang; Merchant, Thomas E.; Farr, Jonathan B.
2016-10-01
We propose an analytical random walk model for proton dose calculation in a laterally homogeneous medium. A formula for the spatial fluence distribution of primary protons is derived. The variance of the spatial distribution is in the form of a distance-squared law of the angular distribution. To improve the accuracy of dose calculation in the Bragg peak region, the energy spectrum of the protons is used. The accuracy is validated against Monte Carlo simulation in water phantoms with either air gaps or a slab of bone inserted. The algorithm accurately reflects the dose dependence on the depth of the bone and can deal with small-field dosimetry. We further applied the algorithm to patients’ cases in the highly heterogeneous head and pelvis sites and used a gamma test to show the reasonable accuracy of the algorithm in these sites. Our algorithm is fast for clinical use.
Hanford Site Annual Report Radiological Dose Calculation Upgrade Evaluation
Energy Technology Data Exchange (ETDEWEB)
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.
International Nuclear Information System (INIS)
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. 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. 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. There was no remarkable difference between the SC and XVMC calculations in the high-dose regions. The difference observed in the low-dose regions may
External dose-rate conversion factors for calculation of dose to the public
Energy Technology Data Exchange (ETDEWEB)
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.
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.
Adjoint Monte Carlo techniques and codes for organ dose calculations
International Nuclear Information System (INIS)
Adjoint Monte Carlo simulations can be effectively used for the estimation of doses in small targets when the sources are extended in large volumes or surfaces. The main features of two computer codes for calculating doses at free points or in organs of an anthropomorphic phantom are described. In the first program (REBEL-3) natural gamma-emitting sources are contained in the walls of a dwelling room; in the second one (POKER-CAMP) the user can specify arbitrary gamma sources with different spatial distributions in the environment: in (or on the surface of) the ground and in the air. 3 figures
International Nuclear Information System (INIS)
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 w,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. (paper)
Prenatal radiation exposure. Dose calculation; Praenatale Strahlenexposition. Dosisermittlung
Energy Technology Data Exchange (ETDEWEB)
Scharwaechter, C.; Schwartz, C.A.; Haage, P. [University Hospital Witten/Herdecke, Wuppertal (Germany). Dept. of Diagnostic and Interventional Radiology; Roeser, A. [University Hospital Witten/Herdecke, Wuppertal (Germany). Dept. of Radiotherapy and Radio-Oncology
2015-05-15
The unborn child requires special protection. In this context, the indication for an X-ray examination is to be checked critically. If thereupon radiation of the lower abdomen including the uterus cannot be avoided, the examination should be postponed until the end of pregnancy or alternative examination techniques should be considered. Under certain circumstances, either accidental or in unavoidable cases after a thorough risk assessment, radiation exposure of the unborn may take place. In some of these cases an expert radiation hygiene consultation may be required. This consultation should comprise the expected risks for the unborn while not perturbing the mother or the involved medical staff. For the risk assessment in case of an in-utero X-ray exposition deterministic damages with a defined threshold dose are distinguished from stochastic damages without a definable threshold dose. The occurrence of deterministic damages depends on the dose and the developmental stage of the unborn at the time of radiation. To calculate the risks of an in-utero radiation exposure a three-stage concept is commonly applied. Depending on the amount of radiation, the radiation dose is either estimated, roughly calculated using standard tables or, in critical cases, accurately calculated based on the individual event. The complexity of the calculation thereby increases from stage to stage. An estimation based on stage one is easily feasible whereas calculations based on stages two and especially three are more complex and often necessitate execution by specialists. This article demonstrates in detail the risks for the unborn child pertaining to its developmental phase and explains the three-stage concept as an evaluation scheme. It should be noted, that all risk estimations are subject to considerable uncertainties.
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.
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
A unique manual method for emergency offsite dose calculations
International Nuclear Information System (INIS)
This paper describes a manual method developed for performance of emergency offsite dose calculations for PP and L's Susquehanna Steam Electric Station. The method is based on a three-part carbonless form. The front page guides the user through selection of the appropriate accident case and inclusion of meteorological and effluent data data. By circling the applicable accident descriptors, the user circles the dose factors on pages 2 and 3 which are then simply multiplied to yield the whole body and thyroid dose rates at the plant boundary, two, five, and ten miles. The process used to generate the worksheet is discussed, including the method used to incorporate the observed terrain effects on airflow patterns caused by the Susquehanna River Valley topography
Comparison of measured and calculated peripheral doses in patients undergoing radiation therapy
International Nuclear Information System (INIS)
Background and purpose: Many papers have been published on the measurement for specific treatment machines and/or techniques of the dose to points outside the primary beam, often called the peripheral dose (PD). Most papers concern measurements in phantoms. We report on the results of a comparison of estimates of the PD, based on these phantom measurements, with PDs measured on patients. Material and methods: A special holder with thermoluminescent dosimeters was placed against the perineum of patients referred to our institute for radiation therapy. The measured dose was then compared with the dose calculated on the basis of published PD data. Results: For all measurements together, the calculated values exceeded the measured PDs by about 9%, with a standard deviation of 35%. The correlation varied between specific subgroups but the difference between measurement and calculation did not exceed 50%. Conclusions: We conclude that published PD data can be used to accurately predict the peripheral dose in the clinical situation
Monte Carlo calculation of received dose from ingestion and inhalation of natural uranium
International Nuclear Information System (INIS)
For the purpose of this study eighty samples are taken from the area Bela Crkva and Vrsac. The activity of radionuclide in the soil is determined by gamma- ray spectrometry. Monte Carlo method is used to calculate effective dose received by population resulting from the inhalation and ingestion of natural uranium. The estimated doses were compared with the legally prescribed levels. (author)
A Mass-Conserving 4D XCAT Phantom for Dose Calculation and Accumulation
Williams, Christopher L; Seco, Joao; James, Sara St; Mak, Raymond H; Berbeco, Ross I; Lewis, John H
2013-01-01
The XCAT phantom is a realistic 4D digital torso phantom that is widely used in imaging and therapy research. However, lung mass is not conserved between respiratory phases of the phantom, making detailed dosimetric simulations and dose accumulation unphysical. A framework is developed to correct this issue by enforcing local mass conservation in the XCAT lung. Dose calculations are performed to assess the implications of neglecting mass conservation, and to demonstrate an application of the phantom to calculate the accumulated delivered dose in an irregularly breathing patient. Monte Carlo methods are used to simulate conventional and SBRT treatment delivery. The spatial distribution of the lung dose was qualitatively changed by the use of mass conservation; however the corresponding DVH did not change significantly. Comparison of the delivered dose with 4DCT-based predictions shows similar lung metric results, however dose differences of 10% can be seen in some spatial regions. Using this tool to simulate p...
A CT-based analytical dose calculation method for HDR 192Ir brachytherapy
International Nuclear Information System (INIS)
Purpose: This article presents an analytical dose calculation method for high-dose-rate 192Ir brachytherapy, taking into account the effects of inhomogeneities and reduced photon backscatter near the skin. The adequacy of the Task Group 43 (TG-43) two-dimensional formalism for treatment planning is also assessed. Methods: The proposed method uses material composition and density data derived from computed tomography images. The primary and scatter dose distributions for each dwell position are calculated first as if the patient is an infinite water phantom. This is done using either TG-43 or a database of Monte Carlo (MC) dose distributions. The latter can be used to account for the effects of shielding in water. Subsequently, corrections for photon attenuation, scatter, and spectral variations along medium- or low-Z inhomogeneities are made according to the radiological paths determined by ray tracing. The scatter dose is then scaled by a correction factor that depends on the distances between the point of interest, the body contour, and the source position. Dose calculations are done for phantoms with tissue and lead inserts, as well as patient plans for head-and-neck, esophagus, and MammoSite balloon breast brachytherapy treatments. Gamma indices are evaluated using a dose-difference criterion of 3% and a distance-to-agreement criterion of 2 mm. PTRANCT MC calculations are used as the reference dose distributions. Results: For the phantom with tissue and lead inserts, the percentages of the voxels of interest passing the gamma criteria (Pγ≥1) are 100% for the analytical calculation and 91% for TG-43. For the breast patient plan, TG-43 overestimates the target volume receiving the prescribed dose by 4% and the dose to the hottest 0.1 cm3 of the skin by 9%, whereas the analytical and MC results agree within 0.4%. Pγ≥1 are 100% and 48% for the analytical and TG-43 calculations, respectively. For the head-and-neck and esophagus patient plans, Pγ≥1 are ≥99
Assessing the Clinical Impact of Approximations in Analytical Dose Calculations for Proton Therapy
Energy Technology Data Exchange (ETDEWEB)
Schuemann, Jan, E-mail: jschuemann@mgh.harvard.edu; 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.
Kanematsu, Nobuyuki
2007-01-01
A simple and efficient variant of the pencil-beam algorithm for dose distribution calculation is proposed. Compared to the conventional pencil-beam algorithms, the new algorithm is intrinsically faster due to minimized computation within the convolution integral. Namely, computation for physical interaction is decoupled from the convolution integral and the convolution kernel is approximated by simple grid-to-grid correlation. Implementation to a treatment planning system for carbon-ion radiotherapy has enabled realistic beam blurring with marginal speed decrease from the broad-beam calculation. Evaluation of a modeled proton pencil beam exhibits inaccuracy within its spread at the Bragg peak when the beam incidence is angled to all the dose grid axes, which will be minimized in broad-beam formation and may be acceptable depending on its relative significance to the other sources of errors. The new algorithm will provide balanced accuracy and speed without technical difficulty for high-resolution dose distrib...
Calculating patient specific doses in X-ray diagnostics and from radiopharmaceuticals
International Nuclear Information System (INIS)
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. When estimating the radiation dose of an individual patient, patient specific calculation methods must be used. 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
Implementation of spot scanning dose optimization and dose calculation for helium ions in Hyperion
DEFF Research Database (Denmark)
Fuchs, Hermann; Alber, Markus; Schreiner, Thomas;
2015-01-01
doses resulted in a γ mean of 0.3, with 3.4% of the values above 1 and γ 1% of 1.5 and better. Treatment plan evaluation showed comparable planning target volume coverage for both particles, with slightly increased coverage for (4)He. Organ at risk (OAR) doses were generally reduced using (4)He, some...
Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis
Energy Technology Data Exchange (ETDEWEB)
Kost, Susan D.; Carver, Diana E.; Stabin, Michael G. [Vanderbilt University, Physics and Astronomy Department, Nashville, TN (United States); Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, TN (United States); Fraser, Nicholas D.; Pickens, David R.; Price, Ronald R.; Hernanz-Schulman, Marta [Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, TN (United States)
2015-11-15
Organ dose is essential for accurate estimates of patient dose from CT. To determine organ doses from a broad range of pediatric patients undergoing diagnostic chest-abdomen-pelvis CT and investigate how these relate to patient size. We used a previously validated Monte Carlo simulation model of a Philips Brilliance 64 multi-detector CT scanner (Philips Healthcare, Best, The Netherlands) to calculate organ doses for 40 pediatric patients (M:F = 21:19; range 0.6-17 years). Organ volumes and positions were determined from the images using standard segmentation techniques. Non-linear regression was performed to determine the relationship between volume CT dose index (CTDI{sub vol})-normalized organ doses and abdominopelvic diameter. We then compared results with values obtained from independent studies. We found that CTDI{sub vol}-normalized organ dose correlated strongly with exponentially decreasing abdominopelvic diameter (R{sup 2} > 0.8 for most organs). A similar relationship was determined for effective dose when normalized by dose-length product (R{sup 2} = 0.95). Our results agreed with previous studies within 12% using similar scan parameters (e.g., bowtie filter size, beam collimation); however results varied up to 25% when compared to studies using different bowtie filters. Our study determined that organ doses can be estimated from measurements of patient size, namely body diameter, and CTDI{sub vol} prior to CT examination. This information provides an improved method for patient dose estimation. (orig.)
Energy Technology Data Exchange (ETDEWEB)
García-Garduño, O. A., E-mail: oagarciag@innn.edu.mx, E-mail: amanda.garcia.g@gmail.com [Laboratorio de Física Médica, Instituto Nacional de Neurología y Neurocirugía, Mexico City 14269, México and Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, Legaria 694, México City 11500, México (Mexico); Rodríguez-Ponce, M. [Departamento de Biofísica, Instituto Nacional de Cancerología, Mexico City 14080, México (Mexico); Gamboa-deBuen, I. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510 (Mexico); Rodríguez-Villafuerte, M. [Instituto de Física, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510 (Mexico); Galván de la Cruz, O. O. [Laboratorio de Física Médica, Instituto Nacional de Neurología y Neurocirugía, Mexico City 14269, México (Mexico); 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
Inverse treatment planning for radiation therapy based on fast Monte Carlo dose calculation
International Nuclear Information System (INIS)
An inverse treatment planning system based on fast Monte Carlo (MC) dose calculation is presented. It allows optimisation of intensity modulated dose distributions in 15 to 60 minutes on present day personal computers. If a multi-processor machine is available, parallel simulation of particle histories is also possible, leading to further calculation time reductions. The optimisation process is divided into two stages. The first stage results influence profiles based on pencil beam (PB) dose calculation. The second stage starts with MC verification and post-optimisation of the PB dose and fluence distributions. Because of the potential to accurately model beam modifiers, MC based inverse planning systems are able to optimise compensator thicknesses and leaf trajectories instead of intensity profiles only. The corresponding techniques, whose implementation is the subject for future work, are also presented here. (orig.)
Dose variations with varying calculation grid size in head and neck IMRT
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Chung, Heeteak [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Fl 32611-8300 (United States); Jin, Hosang [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Fl 32611-8300 (United States); Palta, Jatinder [Department of Radiation Oncology, University of Florida, Gainesville, Fl 32610-0385 (United States); Suh, Tae-Suk [Department of Biomedical Engineering, Catholic University of Korea (Korea, Republic of); Kim, Siyong [Department of Radiation Oncology, University of Florida, Gainesville, Fl 32610-0385 (United States)
2006-10-07
Ever since the advent and development of treatment planning systems, the uncertainty associated with calculation grid size has been an issue. Even to this day, with highly sophisticated 3D conformal and intensity-modulated radiation therapy (IMRT) treatment planning systems (TPS), dose uncertainty due to grid size is still a concern. A phantom simulating head and neck treatment was prepared from two semi-cylindrical solid water slabs and a radiochromic film was inserted between the two slabs for measurement. Plans were generated for a 5400 cGy prescribed dose using Philips Pinnacle{sup 3} TPS for two targets, one shallow ({approx}0.5 cm depth) and one deep ({approx}6 cm depth). Calculation grid sizes of 1.5, 2, 3 and 4 mm were considered. Three clinical cases were also evaluated. The dose differences for the varying grid sizes (2 mm, 3 mm and 4 mm from 1.5 mm) in the phantom study were 126 cGy (2.3% of the 5400 cGy dose prescription), 248.2 cGy (4.6% of the 5400 cGy dose prescription) and 301.8 cGy (5.6% of the 5400 cGy dose prescription), respectively for the shallow target case. It was found that the dose could be varied to about 100 cGy (1.9% of the 5400 cGy dose prescription), 148.9 cGy (2.8% of the 5400 cGy dose prescription) and 202.9 cGy (3.8% of the 5400 cGy dose prescription) for 2 mm, 3 mm and 4 mm grid sizes, respectively, simply by shifting the calculation grid origin. Dose difference with a different range of the relative dose gradient was evaluated and we found that the relative dose difference increased with an increase in the range of the relative dose gradient. When comparing varying calculation grid sizes and measurements, the variation of the dose difference histogram was insignificant, but a local effect was observed in the dose difference map. Similar results were observed in the case of the deep target and the three clinical cases also showed results comparable to those from the phantom study.
The impact of dose calculation algorithms on partial and whole breast radiation treatment plans
Directory of Open Access Journals (Sweden)
Berrang Tanya
2010-12-01
Full Text Available Abstract Background This paper compares the calculated dose to target and normal tissues when using pencil beam (PBC, superposition/convolution (AAA and Monte Carlo (MC algorithms for whole breast (WBI and accelerated partial breast irradiation (APBI treatment plans. Methods Plans for 10 patients who met all dosimetry constraints on a prospective APBI protocol when using PBC calculations were recomputed with AAA and MC, keeping the monitor units and beam angles fixed. Similar calculations were performed for WBI plans on the same patients. Doses to target and normal tissue volumes were tested for significance using the paired Student's t-test. Results For WBI plans the average dose to target volumes when using PBC calculations was not significantly different than AAA calculations, the average PBC dose to the ipsilateral breast was 10.5% higher than the AAA calculations and the average MC dose to the ipsilateral breast was 11.8% lower than the PBC calculations. For ABPI plans there were no differences in dose to the planning target volume, ipsilateral breast, heart, ipsilateral lung, or contra-lateral lung. Although not significant, the maximum PBC dose to the contra-lateral breast was 1.9% higher than AAA and the PBC dose to the clinical target volume was 2.1% higher than AAA. When WBI technique is switched to APBI, there was significant reduction in dose to the ipsilateral breast when using PBC, a significant reduction in dose to the ipsilateral lung when using AAA, and a significant reduction in dose to the ipsilateral breast and lung and contra-lateral lung when using MC. Conclusions There is very good agreement between PBC, AAA and MC for all target and most normal tissues when treating with APBI and WBI and most of the differences in doses to target and normal tissues are not clinically significant. However, a commonly used dosimetry constraint, as recommended by the ASTRO consensus document for APBI, that no point in the contra
Investigation of Nonuniform Dose Voxel Geometry in Monte Carlo Calculations.
Yuan, Jiankui; Chen, Quan; Brindle, James; Zheng, Yiran; Lo, Simon; Sohn, Jason; Wessels, Barry
2015-08-01
The purpose of this work is to investigate the efficacy of using multi-resolution nonuniform dose voxel geometry in Monte Carlo (MC) simulations. An in-house MC code based on the dose planning method MC code was developed in C++ to accommodate the nonuniform dose voxel geometry package since general purpose MC codes use their own coupled geometry packages. We devised the package in a manner that the entire calculation volume was first divided into a coarse mesh and then the coarse mesh was subdivided into nonuniform voxels with variable voxel sizes based on density difference. We name this approach as multi-resolution subdivision (MRS). It generates larger voxels in small density gradient regions and smaller voxels in large density gradient regions. To take into account the large dose gradients due to the beam penumbra, the nonuniform voxels can be further split using ray tracing starting from the beam edges. The accuracy of the implementation of the algorithm was verified by comparing with the data published by Rogers and Mohan. The discrepancy was found to be 1% to 2%, with a maximum of 3% at the interfaces. Two clinical cases were used to investigate the efficacy of nonuniform voxel geometry in the MC code. Applying our MRS approach, we started with the initial voxel size of 5 × 5 × 3 mm(3), which was further divided into smaller voxels. The smallest voxel size was 1.25 × 1.25 × 3 mm(3). We found that the simulation time per history for the nonuniform voxels is about 30% to 40% faster than the uniform fine voxels (1.25 × 1.25 × 3 mm(3)) while maintaining similar accuracy.
Directory of Open Access Journals (Sweden)
Suresh Rana
2013-01-01
Full Text Available Purpose: The purpose of this study is to assess the dosimetric impact of Acuros XB dose calculation algorithm (AXB, in comparisons with Anisotropic Analytical Algorithm (AAA calculations in prostate cancer treatment using RapidArc. Materials and Methods: A computed tomography (CT dataset of low-risk prostate cancer patients treated at Arizona Center for Cancer Care was selected and contoured for prostate, seminal vesicles, and organs at risk (OARs(rectum, bladder, and femur heads. Plans were created for 6 MV photon beam using RapidArc technique in Eclipse treatment planning system. Dose calculations were performed with AAA and AXB for same number of monitor units and identical beam setup. Mean and maximum doses to planning target volume (PTV and OARs were analyzed. Additionally, minimum dose to PTV and V100 was analyzed. Finally, point-dose difference between planar dose distributions of AAA and AXB plans was investigated. Results: The highest dose difference was up to 0.43% (range: 0.05−0.43%, P> 0.05 for PTV and 1.98% (range: 0.22−1.98%, P> 0.05 for OARs with AAA predicting higher dose than AXB. The V100 values of AAA plans (95 % and AXB plans (range: 93.1−97.9 % had an average difference of 0.89±1.47% with no statistical significance (P = 0.25411. The point-dose difference analysis showed that AAA predicted higher dose than AXB at significantly higher percentage (in average 94.15 of total evaluated points. Conclusion: The dosimetric results of this study suggest that the AXB can perform the dose computation comparable to AAA in RapidArc prostate cancer treatment plans that are generated by a partial single-arc technique.
Energy Technology Data Exchange (ETDEWEB)
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.
International Nuclear Information System (INIS)
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
SU-E-T-161: Evaluation of Dose Calculation Based On Cone-Beam CT
Energy Technology Data Exchange (ETDEWEB)
Abe, T; Nakazawa, T; Saitou, Y; Nakata, A; Yano, M [Graduate School of Medicine, Sapporo Medical University, Sapporo, Hokkaido (Japan); Tateoka, K [Graduate School of Medicine, Sapporo Medical University, Sapporo, Hokkaido (Japan); Radiation Therapy Research Institute, Social Medical Corporation Teishinkai, Sapporo, Hokkaido (Japan); Fujimoto, K [Radiation Therapy Research Institute, Social Medical Corporation Teishinkai, Sapporo, Hokkaido (Japan); Sakata, K [Graduate School of Medicine, Sapporo Medical University, Sapporo, Hokkaido (Japan); Sapporo Medical University, Sapporo, Hokkaido (Japan)
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.
Fast pencil beam dose calculation for proton therapy using a double-Gaussian beam model
Directory of Open Access Journals (Sweden)
Joakim eda Silva
2015-12-01
Full Text Available The highly conformal dose distributions produced by scanned proton pencil beams 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 pencil beam 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 pencil beam algorithm for proton therapy running on a GPU. We employ two different parametrizations 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 pencil beams in water. Despite the large width of the halo contribution, we show how in either case the second Gaussian can be included whilst 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%. Further, the calculation time is relatively unaffected by the parametrization 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.
Postimplant Dosimetry Using a Monte Carlo Dose Calculation Engine: A New Clinical Standard
International Nuclear Information System (INIS)
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) D90 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
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Klüter, Sebastian, E-mail: sebastian.klueter@med.uni-heidelberg.de; Schubert, Kai; Lissner, Steffen; Sterzing, Florian; Oetzel, Dieter; Debus, Jürgen [Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany, and Heidelberg Institute for Radiation Oncology (HIRO), Im Neuenheimer Feld 400, 69120 Heidelberg, Germany, and German Consortium for Translational Cancer Research (DKTK), Im Neuenheimer Feld 400, 69120 Heidelberg (Germany); Schlegel, Wolfgang [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Oelfke, Uwe [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany and Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG (United Kingdom); Nill, Simeon [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG (United Kingdom)
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
International Nuclear Information System (INIS)
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
SU-E-I-28: Evaluating the Organ Dose From Computed Tomography Using Monte Carlo Calculations
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Ono, T; Araki, F [Faculty of Life Sciences, Kumamoto University, Kumamoto (Japan)
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.
Calculation of mean dose deposited in expended volume around an ion path
Institute of Scientific and Technical Information of China (English)
LiuXiao－Wei; ZhangChun－Xiang
1998-01-01
Using the relation of radial dose distributioin which is inverse proportion to suqare of radial distance,and considering angular distribution of secondary electrons,an analytical formula of mean dose deposited in extended volume around an ion is given and the inactivation cross sections of heavy ions are calculated.The results are in reasonable agreement with experimental data.Compared to the numerical integral methods,the method using analytical formulae is straightforward and simple.
Improvement of neutron dose calculation algorithm using panasonic UD-809P type albedo TLD
International Nuclear Information System (INIS)
Panasonic UD-809P type albedo TLD mounted on a water phantom were used to measure neutron personal dose equivalent in a Korean nuclear power plant. From the measured TL readings, personal dose equivalents from thermal, epithermal and fast neutrons were evaluated by using a method adopted in a neutron dose calculation algorithm for Panasonic UD-809P type albedo TLD, which was recommended in a Panasonic TLD System User's Manual. The results showed that personal dose equivalent for fast neutrons could not be adequately evaluated in a field with high thermal neutron fraction. This seems to be related to the incomplete incidence of albedo thermal neutrons to the TLD. In order to calculate the personal dose equivalent from fast neutrons in the field condition to be encountered in a nuclear power plant, new method for the neutron dose calculation algorithm were suggested. For a known energy spectrum, it is very easy and simple to use this method for the evaluation of neutron personal dose equivalent
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Chibani, Omar, E-mail: omar.chibani@fccc.edu; C-M Ma, Charlie [Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)
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
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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
SU-E-T-27: A Tool for Routine Quality Assurance of Radiotherapy Dose Calculation Software
International Nuclear Information System (INIS)
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
Recommended environmental dose calculation methods and Hanford-specific parameters
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Schreckhise, R.G.; Rhoads, K.; Napier, B.A.; Ramsdell, J.V. (Pacific Northwest Lab., Richland, WA (United States)); Davis, J.S. (Westinghouse Hanford Co., Richland, WA (United States))
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.
Neutrons and Gamma-Ray Dose Calculations in Subcritical Reactor Facility Using MCNP
Directory of Open Access Journals (Sweden)
Ned Xoubi
2016-06-01
Full Text Available In nuclear experimental, training and teaching laboratories such as a subcritical reactor facility, huge measures of external radiation doses could be caused by neutron and gamma radiation. It becomes imperative to place the health and safety of staff and students in the reactor facility under proper scrutiny. The protection of these individuals against ionization radiation is facilitated by expected dose mapping and shielding calculations. A three-dimensional (3D Monte Carlo model was developed to calculate the dose rate from neutrons and gamma, using the ANSI/ANS-6.1.1 and the ICRP-74 flux-to-dose conversion factors. Estimation for the dose was conducted across 39 areas located throughout the reactor hall of the facility and its training platform. It was found that the range of the dose rate magnitude is between 7.50 E−01 μSv/h and 1.96 E−04 μSv/h in normal operation mode. During reactor start-up/shut-down mode, it was observed that a large area of the facility can experience exposure to a significant radiation field. This field ranges from 2.99 E+03 μSv/h to 3.12 E+01 μSv/h. There exists no noticeable disparity between results using the ICRP-74 or ANSI/ANS-6.1.1 flux-to-dose rate conversion factors. It was found that the dose rate due to gamma rays is higher than that of neutrons.
Directory of Open Access Journals (Sweden)
Peiman Haddad
2014-02-01
Conclusion: In this study, the mean testis dose of radiation was 3.77 Gy, similar to the dose calculated by the planning software (4.11 Gy. This dose could be significantly harmful for spermatogenesis, though low doses of scattered radiation to the testis in fractionated radiotherapy might be followed with better recovery. Based on above findings, careful attention to testicular dose in radiotherapy of rectal cancer for the males desiring continued fertility seems to be required.
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Moore, Bria M.; Brady, Samuel L., E-mail: samuel.brady@stjude.org; Kaufman, Robert A. [Department of Radiological Sciences, St Jude Children' s Research Hospital, Memphis, Tennessee 38105 (United States); Mirro, Amy E. [Department of Biomedical Engineering, Washington University, St Louis, Missouri 63130 (United States)
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
Interpretation of animal data in the calculation of doses from new radiolabelled compounds
International Nuclear Information System (INIS)
The Radionuclide Biokinetics Group of the Biomedical Effects Department at NRPB provides a dose calculation service for pharmaceutical companies and associated laboratories which plan to administer radiolabelled drugs to human volunteers as part of their research and development programmes for new compounds. Animal data provided by these companies are used to estimate the likely doses to humans from administration of the compound. The dose estimate then accompanies the pharmaceutical company's application for approval from the UK Administration of Radioactive Substances Advisory Committee (ARSAC). The method of calculation, the interpretation of the animal data and the range of results obtained are discussed. In addition, the effect of the use of the new ICRP tissue weighting factors in the calculations is considered. (Author)
International Nuclear Information System (INIS)
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
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Fogliata, Antonella; Nicolini, Giorgia; Vanetti, Eugenio; Clivio, Alessandro; Cozzi, Luca [Oncology Institute of Southern Switzerland, Medical Physics Unit, 6504 Bellinzona (Switzerland); Winkler, Peter [Department of Therapeutic Radiology and Oncology, University Hospital Graz (Austria)], E-mail: lucozzi@iosi.ch
2008-05-07
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 {gamma} 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{sup -3}, respectively, and average peak densities of 0.17 {+-} 0.03 and 0.09 {+-} 0.02 g cm{sup -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 {gamma} 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 {gamma} > 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 {gamma} > 1 in average inferior to 2% in FB and 4
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
Calculation of depth-dose distribution of intermediate energy heavy-ion beams
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Based on the characteristics of the interactions between intermediate energy heavy-ion beam and target matter, a method to calculate the depth-dose distribution of heavy-ion beams with intermediate energy (10 -100 MeV/u) is presented. By comparing high energy beams where projectile fragmentation is overwhelm ing with lowenergies where energy straggling is the sole factor instead, a crescent energy spread with increasing depth and a simple fragmentation assumption were included for the depth-dose calculation of the intermediate energy beam. Rel ative depth-dose curves of carbon and oxygen ion beams with intermediate energie s were computed according to the method here. Comparisons between the calculated relative doses and measurements are shown. The calculated Bragg curves, especially the upstream and downstream Bragg peaks, agree with the measured data. Differences between the two results appear only around the peak regions because of th e limitations of the calculation and experimental conditions, but the calculated curves generally reproduce the measured data within the experimental errors. Th e reasons for the divergences were analyzed carefully and the magnitudes of the deviations are given.
Dose calculation for accident situations at TRIGA research reactor using LEU fuel type
International Nuclear Information System (INIS)
The 14 MW TRIGA R.R. is a unique design of TRIGA conception. The core was fully converted in May 2006 to use LEU fuel instead of the HEU fuel type. The core contains 29 fuel assemblies, 8 control rods and beryllium reflector, associated instrumentation and controls. The U-235 enrichment for TRIGA - HEU fuel is 93.15 wt % and for TRIGA - LEU is 40.00 wt %. The differences between the two fuel types, as shown by the calculations, will results in a higher core inventory especially for heavy elements (i.e. actinides and transuranium elements), but modifications for noble gases, halogens and other volatile fission products are not so important. Dose calculations for an hypothetical accident scenario was considered and dose and radiological consequence calculations were performed. The results of the calculations and a discussion related on the differences between the consequences in the two cases are also presented. (authors)
RADIATION DOSE CALCULATION FOR FUEL HANDLING FACILITY CLOSURE CELL EQUIPMENT
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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
International Nuclear Information System (INIS)
This is the first report to provide radiation doses, arising from inhalation of radon itself, in mice and rats. To quantify absorbed doses to organs and tissues in mice, rats, and humans, we computed the behavior of inhaled radon in their bodies on the basis of a physiologically based pharmacokinetic (PBPK) model. It was assumed that radon dissolved in blood entering the gas exchange compartment is transported to any tissue by the blood circulation to be instantaneously distributed according to a tissue/blood partition coefficient. The calculated concentrations of radon in the adipose tissue and red bone marrow following its inhalation were much higher than those in the others, because of the higher partition coefficients. Compared with a previous experimental data for rats and model calculation for humans, the present calculation was proved to be valid. Absorbed dose rates to organs and tissues were estimated to be within the range of 0.04-1.4 nGy (Bqm-3)-1 day-1 for all the species. Although the dose rates are not so high, it may be better to pay attention to the dose to the red bone marrow from the perspective of radiation protection. For more accurate dose assessment, it is necessary to update tissue/blood partition coefficients of radon that strongly govern the result of the PBPK modeling. (author)
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Lesperance, Marielle; Inglis-Whalen, M.; Thomson, R. M., E-mail: rthomson@physics.carleton.ca [Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa K1S 5B6 (Canada)
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
International Nuclear Information System (INIS)
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 with125I, 103Pd, or 131Cs 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 simulation by up to 16
Zhang, Aizhen; Wen, Ning; Nurushev, Teamour; Burmeister, Jay; Chetty, Indrin J
2013-01-01
based on point-dose prescription. The eMC algorithm calculation was characterized by deeper penetration in the low-density regions, such as lung and air cavities. As a result, the mean dose in the low-density regions was underestimated using PB algorithm. The eMC computation time ranged from 5 min to 66 min on a single 2.66 GHz desktop, which is comparable with PB algorithm calculation time for the same resolution level. PMID:23470937
Dose calculation method with 60-cobalt gamma rays in total body irradiation
Scaff, L A M
2001-01-01
Physical factors associated to total body irradiation using sup 6 sup 0 Co gamma rays beams, were studied in order to develop a calculation method of the dose distribution that could be reproduced in any radiotherapy center with good precision. The method is based on considering total body irradiation as a large and irregular field with heterogeneities. To calculate doses, or doses rates, of each area of interest (head, thorax, thigh, etc.), scattered radiation is determined. It was observed that if dismagnified fields were considered to calculate the scattered radiation, the resulting values could be applied on a projection to the real size to obtain the values for dose rate calculations. In a parallel work it was determined the variation of the dose rate in the air, for the distance of treatment, and for points out of the central axis. This confirm that the use of the inverse square law is not valid. An attenuation curve for a broad beam was also determined in order to allow the use of absorbers. In this wo...
Fewer Doses of HPV Vaccine Result in Immune Response Similar to Three-Dose Regimen
... Press Releases NCI News Note Fewer doses of HPV vaccine result in immune response similar to three- ... report that two doses of a human papillomavirus (HPV) vaccine, trademarked as Cervarix, resulted in similar serum ...
Construction of new skin models and calculation of skin dose coefficients for electron exposures
Yeom, Yeon Soo; Kim, Chan Hyeong; Nguyen, Thang Tat; Choi, Chansoo; Han, Min Cheol; Jeong, Jong Hwi
2016-08-01
The voxel-type reference phantoms of the International Commission on Radiological Protection (ICRP), due to their limited voxel resolutions, cannot represent the 50- μm-thick radiosensitive target layer of the skin necessary for skin dose calculations. Alternatively, in ICRP Publication 116, the dose coefficients (DCs) for the skin were calculated approximately, averaging absorbed dose over the entire skin depth of the ICRP phantoms. This approximation is valid for highly-penetrating radiations such as photons and neutrons, but not for weakly penetrating radiations like electrons due to the high gradient in the dose distribution in the skin. To address the limitation, the present study introduces skin polygon-mesh (PM) models, which have been produced by converting the skin models of the ICRP voxel phantoms to a high-quality PM format and adding a 50- μm-thick radiosensitive target layer into the skin models. Then, the constructed skin PM models were implemented in the Geant4 Monte Carlo code to calculate the skin DCs for external exposures of electrons. The calculated values were then compared with the skin DCs of the ICRP Publication 116. The results of the present study show that for high-energy electrons (≥ 1 MeV), the ICRP-116 skin DCs are, indeed, in good agreement with the skin DCs calculated in the present study. For low-energy electrons (energies. Besides, regardless of the small tissue weighting factor of the skin ( w T = 0.01), the discrepancies in the skin dose were found to result in significant discrepancies in the effective dose, demonstarting that the effective DCs in ICRP-116 are not reliable for external exposure to electrons.
International Nuclear Information System (INIS)
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
TH-A-19A-06: Site-Specific Comparison of Analytical and Monte Carlo Based Dose Calculations
Energy Technology Data Exchange (ETDEWEB)
Schuemann, J; Grassberger, C; Paganetti, H [Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Dowdell, S [Illawarra Shoalhaven Local Health District, Wollongong (Australia)
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
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Han Tao; Followill, David; Repchak, Roman; Molineu, Andrea; Howell, Rebecca; Salehpour, Mohammad [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Mikell, Justin [Department of Radiation Physics, the University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); Mourtada, Firas [Department of Radiation Physics, the University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Oncology, Christiana Care Health System, Newark, Delaware 19713 (United States)
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
Recent adiabaticity results from orbit calculations
International Nuclear Information System (INIS)
There has been much activity recently in an attempt to find a straightforward method of predicting the limits of adiabatic behavior in high-beta magnetic-mirror configurations. The particle-orbit code TIBRO was used to obtain numerical results on nonadiabatic behavior with which the predictions of theoretical expressions can be compared. These results are summarized. (MOW)
International Nuclear Information System (INIS)
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
Individual Dose Calculations with Use of the Revised Techa River Dosimetry System TRDS-2009D
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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
Calculation of organ doses in x-ray examinations of premature babies
International Nuclear Information System (INIS)
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
Optimization in radiotherapy treatment planning thanks to a fast dose calculation method
International Nuclear Information System (INIS)
This thesis deals with the radiotherapy treatments planning issue which need a fast and reliable treatment planning system (TPS). The TPS is composed of a dose calculation algorithm and an optimization method. The objective is to design a plan to deliver the dose to the tumor while preserving the surrounding healthy and sensitive tissues. The treatment planning aims to determine the best suited radiation parameters for each patient's treatment. In this thesis, the parameters of treatment with IMRT (Intensity modulated radiation therapy) are the beam angle and the beam intensity. The objective function is multi-criteria with linear constraints. The main objective of this thesis is to demonstrate the feasibility of a treatment planning optimization method based on a fast dose-calculation technique developed by (Blanpain, 2009). This technique proposes to compute the dose by segmenting the patient's phantom into homogeneous meshes. The dose computation is divided into two steps. The first step impacts the meshes: projections and weights are set according to physical and geometrical criteria. The second step impacts the voxels: the dose is computed by evaluating the functions previously associated to their mesh. A reformulation of this technique makes possible to solve the optimization problem by the gradient descent algorithm. The main advantage of this method is that the beam angle parameters could be optimized continuously in 3 dimensions. The obtained results in this thesis offer many opportunities in the field of radiotherapy treatment planning optimization. (author)
Dose calculations using artificial neural networks: A feasibility study for photon beams
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.
Dose calculations using artificial neural networks: A feasibility study for photon beams
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Vasseur, Aurelien [University of Franche-Comte, IRMA/CREST Femto-ST, Portes du Jura, 4 place Tharradin, BP 71427, 25211 Montbeliard Cedex (France); University of Franche-Comte, AND/LIFC, rue Engel Gros, 90016 Belfort (France)], E-mail: aurelien.vasseur@gmail.com; Makovicka, Libor; Martin, Eric [University of Franche-Comte, IRMA/CREST Femto-ST, Portes du Jura, 4 place Tharradin, BP 71427, 25211 Montbeliard Cedex (France); Sauget, Marc [University of Franche-Comte, IRMA/CREST Femto-ST, Portes du Jura, 4 place Tharradin, BP 71427, 25211 Montbeliard Cedex (France); University of Franche-Comte, AND/LIFC, rue Engel Gros, 90016 Belfort (France); Contassot-Vivier, Sylvain; Bahi, Jacques [University of Franche-Comte, AND/LIFC, rue Engel Gros, 90016 Belfort (France)
2008-04-15
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 150x1x150 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.
Exposure Dose Calculation In Some Serious Accident Cases For Irradiation Facility SVST-Co60/B
International Nuclear Information System (INIS)
Two serious accidents which could happen to SVST-Co60/B irradiator are assumed: the source racks are jammed and could not return to the storage position and a source pencil is knocked out on the production maze by a tote-box. By using MCNP code the calculation of exposure doses in the approach zone and the residential area outside the facility for two above-mentioned cases has been carried out and its results for both cases show that the exposure doses in the approach zone are higher than the limit dose (>100 mSv/h) but the exposure doses in the residential area are still in safe range (-2 mSv/h). (author)
Real-time 3D dose calculation and display: a tool for plan optimization
International Nuclear Information System (INIS)
Purpose: Both human and computer optimization of treatment plans have advantages; humans are much better at global pattern recognition, and computers are much better at detailed calculations. A major impediment to human optimization of treatment plans by manipulation of beam parameters is the long time required for feedback to the operator on the effectiveness of a change in beam parameters. Our goal was to create a real-time dose calculation and display system that provides the planner with immediate (fraction of a second) feedback with displays of three-dimensional (3D) isodose surfaces, digitally reconstructed radiographs (DRRs), dose-volume histograms, and/or a figure of merit (FOM) (i.e., a single value plan score function). This will allow the experienced treatment planner to optimize a plan by adjusting beam parameters based on a direct indication of plan effectiveness, the FOM value, and to use 3D display of target, critical organs, DRRs, and isodose contours to guide changes aimed at improving the FOM value. Methods and Materials: We use computer platforms that contain easily utilized parallel processors and very tight coupling between calculation and display. We ported code running on a network of two workstations and an array of transputers to a single multiprocessor workstation. Our current high-performance graphics workstation contains four 150-MHz processors that can be readily used in a shared-memory multithreaded calculation. Results: When a 10 x 10-cm beam is moved, using an 8-mm dose grid, the full 3D dose matrix is recalculated using a Bentley-Milan-type dose calculation algorithm, and the 3D dose surface display is then updated, all in < 0.1 s. A 64 x 64-pixel DRR calculation can be performed in < 0.1 s. Other features, such as automated aperture calculation, are still required to make real-time feedback practical for clinical use. Conclusion: We demonstrate that real-time plan optimization using general purpose multiprocessor workstations is a
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.
International Nuclear Information System (INIS)
The ANISN code has been used in this study to evaluate the attenuation of neutron beams of various spectra incident normally on slabs of different kinds of concrete. Spectra of the most common sources (Am-Be and Cf-252) and those of giant resonance neutrons, produced at electron accelerators, were studied. The concretes examined had densities between 2.1 and 4.64 g.cm-3. The calculation were made in terms of the deep dose equivalent index, the effective dose equivalent and the ambient dose equivalent. Values of attenuation length in the various materials were derived from the attenuation curves. The results found should allow for useful evaluations in every day practice for health physicist
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Landry, Guillaume; Reniers, Brigitte; Murrer, Lars; Lutgens, Ludy; Bloemen-Van Gurp, Esther; Pignol, Jean-Philippe; Keller, Brian; Beaulieu, Luc; Verhaegen, Frank [Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, de l' Universite Laval, CHUQ, Pavillon L' Hotel-Dieu de Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d' Optique, Universite Laval, Quebec G1K 7P4 (Canada); Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands) and Medical Physics Unit, McGill University, Montreal General Hospital, Montreal, Quebec H3G 1A4 (Canada)
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
International Nuclear Information System (INIS)
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: 125I, 103Pd, 131Cs, 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 Dw,m as opposed to dose to a small mass of medium in medium Dm,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 125I 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 D90 values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using 103Pd 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 D90 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 in the mean compositions of tissues affect low energy
Organ dose calculation in CT based on scout image data and automatic image registration
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Kortesniemi, Mika; Salli, Eero; Seuri, Raija [HUS Helsinki Medical Imaging Center, Univ. of Helsinki, Helsinki (Finland)], E-mail: mika.kortesniemi@hus.fi
2012-10-15
Background Computed tomography (CT) has become the main contributor of the cumulative radiation exposure in radiology. Information on cumulative exposure history of the patient should be available for efficient management of radiation exposures and for radiological justification. Purpose To develop and evaluate automatic image registration for organ dose calculation in CT. Material and Methods Planning radiograph (scout) image data describing CT scan ranges from 15 thoracic CT examinations (9 men and 6 women) and 10 abdominal CT examinations (6 men and 4 women) were co-registered with the reference trunk CT scout image. 2-D affine transformation and normalized correlation metric was used for image registration. Longitudinal (z-axis) scan range coordinates on the reference scout image were converted into slice locations on the CT-Expo anthropomorphic male and female models, following organ and effective dose calculations. Results The average deviation of z-location of studied patient images from the corresponding location in the reference scout image was 6.2 mm. The ranges of organ and effective doses with constant exposure parameters were from 0 to 28.0 mGy and from 7.3 to 14.5 mSv, respectively. The mean deviation of the doses for fully irradiated organs (inside the scan range), partially irradiated organs and non-irradiated organs (outside the scan range) was 1%, 5%, and 22%, respectively, due to image registration. Conclusion The automated image processing method to registrate individual chest and abdominal CT scout radiograph with the reference scout radiograph is feasible. It can be used to determine the individual scan range coordinates in z-direction to calculate the organ dose values. The presented method could be utilized in automatic organ dose calculation in CT for radiation exposure tracking of the patients.
Neutron spectra and dose equivalents calculated in tissue for high-energy radiation therapy
Energy Technology Data Exchange (ETDEWEB)
Kry, Stephen F.; Howell, Rebecca M.; Salehpour, Mohammad; Followill, David S. [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)
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
International Nuclear Information System (INIS)
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
Clouvas, A; Antonopoulos-Domis, M; Silva, J
2000-01-01
The dose rate conversion factors D/sub CF/ (absorbed dose rate in air per unit activity per unit of soil mass, nGy h/sup -1/ per Bq kg/sup -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/sub 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 ag...
Modelling lateral beam quality variations in pencil kernel based photon dose calculations
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
Reassessment and reinforcement of nuclear decay database used for dose calculation
International Nuclear Information System (INIS)
A nuclear decay database of ICRP Publ.38 has been used for calculating dose coefficients for intake of radionuclides and effective dose rates for submersion. Publ.38 were compiled from decay data sets of the Evaluated Nuclear Structure Data File (ENSDF), which were prepared in the 1970's. It is very important to update the database by taking the recent revision of the ENSDF into account. This paper presents a comprehensive study on a reassessment and reinforcement of the nuclear decay database of Publ.38. For all 820 radionuclides listed in Publ.38, half-lives, branching ratios of the decay modes, and energies and intensities of radiations emitted were calculated from decay data sets of the ENSDF, the latest version in 1997, and compared with those of Publ.38. In most nuclides, the calculated values from the ENSDF were in good agreement with those of Publ.38. However, significant differences in the half-lives and the total energies of radiations were found in several nuclides, notably in 60Fe, 79Se, 80Sr, 108mAg, 126Ba, 202Pb, and 231Th. It was shown that internal dose coefficients of 202Pb calculated using the two decay data differ by a factor of two as a result of revision in the decay data sets. The results suggest that the nuclear decay data of Publ.38 are still adequate for dose calculation in most nuclides but the update of the data is required for several ones. Nuclear decay data for dose calculation were compiled from the ENSDF for 204 nuclides that are not listed in Publ.38. The compiled data involve 162 nuclides with half-lives ≥10 min, 28 daughters and 14 nuclides that are important in fusion reactor facilities. Analysis of the decay data sets was performed to check their self-consistency and possible revisions were made for their format and syntax errors, level schemes, normalization records, and so on . The revised data sets were processed by the EDISTR code to compile the decay data of Publ.38 form. The data were presented as a data book, JAERI Data
Digital Breast Tomosynthesis: Comparison of Different Methods to Calculate Patient Doses
International Nuclear Information System (INIS)
Different methods have been proposed in the literature to calculate the dose to the patient's breast in 3-D mammography. The methods described by Dance et al. and Sechopoulos et al. have been compared in this study using the two tomosynthesis systems available in the authors' hospitals (Siemens and Hologic). There is a small but significant difference of 23% for the first X ray system and 13% for the second system between dose calculations performed with Dance's method and Sechopoulos' method. These differences are mainly due to the fact that the two sets of authors used different breast models for their Monte Carlo calculations. For each system, the calculated breast doses were compared with the dose values indicated on the system console. Good agreement was found when the method of Dance et al. was used for a breast glandularity based on the patient age. For the Siemens system, the calculated doses were 5% lower than the indicated dose and for the Hologic system, the calculated doses were 12% higher. Finally, the 3-D dose values were compared with the doses found in a large 2-D dosimetry study. The dose values for tomosynthesis on the Siemens system were almost double the doses in one view 2-D digital mammography. For a typical breast of thickness 45 mm, the dose of one 2-D view was 0.83 mGy and for one 3-D view 1.79 mGy. (author)
Monte Carlo calculations of the impact of a hip prosthesis on the dose distribution
International Nuclear Information System (INIS)
Because of the ageing of the population, an increasing number of patients with hip prostheses are undergoing pelvic irradiation. Treatment planning systems (TPS) currently available are not always able to accurately predict the dose distribution around such implants. In fact, only Monte Carlo simulation has the ability to precisely calculate the impact of a hip prosthesis during radiotherapeutic treatment. Monte Carlo phantoms were developed to evaluate the dose perturbations during pelvic irradiation. A first model, constructed with the DOSXYZnrc usercode, was elaborated to determine the dose increase at the tissue-metal interface as well as the impact of the material coating the prosthesis. Next, CT-based phantoms were prepared, using the usercode CTCreate, to estimate the influence of the geometry and the composition of such implants on the beam attenuation. Thanks to a program that we developed, the study was carried out with CT-based phantoms containing a hip prosthesis without metal artefacts. Therefore, anthropomorphic phantoms allowed better definition of both patient anatomy and the hip prosthesis in order to better reproduce the clinical conditions of pelvic irradiation. The Monte Carlo results revealed the impact of certain coatings such as PMMA on dose enhancement at the tissue-metal interface. Monte Carlo calculations in CT-based phantoms highlighted the marked influence of the implant's composition, its geometry as well as its position within the beam on dose distribution
International Nuclear Information System (INIS)
The normal tissue complication probability (NTCP) is a predictor of radiobiological effect for organs at risk (OAR). The calculation of the NTCP is based on the dose-volume-histogram (DVH) which is generated by the treatment planning system after calculation of the 3D dose distribution. Including the NTCP in the objective function for intensity modulated radiation therapy (IMRT) plan optimization would make the planning more effective in reducing the postradiation effects. However, doing so would lengthen the total planning time. The purpose of this work is to establish a method for NTCP determination, independent of a DVH calculation, as a quality assurance check and also as a mean of improving the treatment planning efficiency. In the study, the CTs of ten randomly selected prostate patients were used. IMRT optimization was performed with a PINNACLE3 V 6.2b planning system, using planning target volume (PTV) with margins in the range of 2 to 10 mm. The DVH control points of the PTV and OAR were adapted from the prescriptions of Radiation Therapy Oncology Group protocol P-0126 for an escalated prescribed dose of 82 Gy. This paper presents a new model for the determination of the rectal NTCP (RNTCP). The method uses a special function, named GVN (from Gy, Volume, NTCP), which describes the RNTCP if 1 cm3 of the volume of intersection of the PTV and rectum (Rint) is irradiated uniformly by a dose of 1 Gy. The function was 'geometrically' normalized using a prostate-prostate ratio (PPR) of the patients' prostates. A correction of the RNTCP for different prescribed doses, ranging from 70 to 82 Gy, was employed in our model. The argument of the normalized function is the Rint, and parameters are the prescribed dose, prostate volume, PTV margin, and PPR. The RNTCPs of another group of patients were calculated by the new method and the resulting difference was <±5% in comparison to the NTCP calculated by the PINNACLE3 software where Kutcher's dose-response model for
International Nuclear Information System (INIS)
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® (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 Pinnacle3 (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 ±1σ 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 dose calculations had an average
A comparison of measured and calculated organ doses from CT examinations
Energy Technology Data Exchange (ETDEWEB)
Calzado, A.; Ruiz Sanz, S.; Melchor, M.; Vano, E. [Universidad Complutense, Madrid (Spain). Facultad de Medicina
1995-12-31
Organ doses from a set of frequent CT examinations have been estimated from measurements in a physical anthropomorphic phantom (Remab system) by using thermoluminescence dosemeters. For the same examination techniques, organ dose coefficients (taken from the literature) obtained by Monte Carlo techniques and using mathematical phantoms. The results arrived at by the two methods are compared, trying to explain the most significant differences and their influence on the estimated values of effective dose. The experimental and calculated outcomes from such simulations are also compared to the mean dosimetric results on patients from a 1991 regional survey of CT practice in the area of Madrid. Some comments about the complementary use of information coming from both methods are made. (Author).
Sato, Tatsuhiko; Endo, Akira; Sihver, Lembit; Niita, Koji
2011-03-01
Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients in the units of Gy.cm(2) and Sv.cm(2), respectively, and cosmic-ray fluxes around spacecrafts in the unit of cm(-2) s(-1). The dose conversion coefficients employed in the calculation were evaluated using the general-purpose particle and heavy ion transport code system PHITS coupled to the male and female adult reference computational phantoms, which were released as a common ICRP/ICRU publication. The cosmic-ray fluxes inside and near to spacecrafts were also calculated by PHITS, using simplified geometries. The accuracy of the obtained absorbed-dose and dose-equivalent rates was verified by various experimental data measured both inside and outside spacecrafts. The calculations quantitatively show that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents, because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors. These results demonstrate the usefulness of dose conversion coefficients in space dosimetry. PMID:20835833
Monte-Carlo Method Python Library for dose distribution Calculation in Brachytherapy
International Nuclear Information System (INIS)
The Cs-137 Brachytherapy treatment is performed in Madagascar since 2005. Time treatment calculation for prescribed dose is made manually. Monte-Carlo Method Python library written at Madagascar INSTN is experimentally used to calculate the dose distribution on the tumour and around it. The first validation of the code was done by comparing the library curves with the Nucletron company curves. To reduce the duration of the calculation, a Grid of PC's is set up with listner patch run on each PC. The library will be used to modelize the dose distribution in the CT scan patient picture for individual and better accuracy time calculation for a prescribed dose.
Patient-specific Monte Carlo dose calculations for 103Pd breast brachytherapy
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
Calculating N fertilizer doses for oil-seed rape using plant and soil data
MAKOWSKI, DAVID; Maltas, Alexandra; Morison, Muriel; Reau, Raymond
2005-01-01
International audience We evaluated the economic and environmental interests of a balance-sheet method recently developed for calculating N fertilizer doses for oil-seed rape. The evaluation was performed using simple models of yield, grain oil content, and residual soil mineral nitrogen responses to applied N. The models were fitted to 53 fertilizer trials carried out in France between 1993 and 1999. The results show that the use of the balance-sheet method decreases the variability of fa...
A GPU implementation of a track-repeating algorithm for proton radiotherapy dose calculations
Yepes, Pablo P; Taddei, Phillip J
2010-01-01
An essential component in proton radiotherapy is the algorithm to calculate the radiation dose to be delivered to the patient. The most common dose algorithms are fast but they are approximate analytical approaches. However their level of accuracy is not always satisfactory, especially for heterogeneous anatomic areas, like the thorax. Monte Carlo techniques provide superior accuracy, however, they often require large computation resources, which render them impractical for routine clinical use. Track-repeating algorithms, for example the Fast Dose Calculator, have shown promise for achieving the accuracy of Monte Carlo simulations for proton radiotherapy dose calculations in a fraction of the computation time. We report on the implementation of the Fast Dose Calculator for proton radiotherapy on a card equipped with graphics processor units (GPU) rather than a central processing unit architecture. This implementation reproduces the full Monte Carlo and CPU-based track-repeating dose calculations within 2%, w...
Radial Dose Profiles: Calculation Refinements and Sensitivities to Single Event Effects Analysis
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.
A centralized dose calculation system for radiation therapy.
Xiao, Y; Galvin, J
2000-05-01
Centralization of treatment planning in a radiation therapy department is a realistic strategy to achieve an integrated and quality-controlled planning system, especially for institutions with numerous affiliations. The rapid evolution of computer hardware and software technology makes this a distinct possibility. However, the procedure of three-dimensional treatment planning involves a number of steps, such as: (1) input of patient computed tomography (CT) images and contour information; (2) interactions with local devices such as a film digitizer; and (3) output of beam information to be integrated with the record and verify the system. A full-fledged realization of the web-based centralized three-dimensional treatment planning system will require an extensive commercial development effort. We have developed and incorporated a web-based Timer/Monitor Unit (MU) program as a first step towards the full implementation of a centralized treatment planning system. The software application was developed in JAVA language. It uses the internet server and client technology. With one server that can handle multiple threads, it is a simple process to access the application anywhere on the network with an internet browser. Both the essential data needed for the calculation and the results are stored on the server, which centralizes the maintenance of the software and the storage of patient information.
Deterministic Partial Differential Equation Model for Dose Calculation in Electron Radiotherapy
Duclous, Roland; Frank, Martin
2009-01-01
Treatment with high energy ionizing radiation is one of the main methods in modern cancer therapy that is in clinical use. During the last decades, two main approaches to dose calculation were used, Monte Carlo simulations and semi-empirical models based on Fermi-Eyges theory. A third way to dose calculation has only recently attracted attention in the medical physics community. This approach is based on the deterministic kinetic equations of radiative transfer. Starting from these, we derive a macroscopic partial differential equation model for electron transport in tissue. This model involves an angular closure in the phase space. It is exact for the free-streaming and the isotropic regime. We solve it numerically by a newly developed HLLC scheme based on [BerCharDub], that exactly preserves key properties of the analytical solution on the discrete level. Several numerical results for test cases from the medical physics literature are presented.
Calculation of conversion factors for effective dose for various interventional radiology procedures
Energy Technology Data Exchange (ETDEWEB)
Compagnone, Gaetano; Giampalma, Emanuela; Domenichelli, Sara; Renzulli, Matteo; Golfieri, Rita [Medical Physics Department, S. Orsola-Malpighi University Hospital, Via Massarenti 9, 40138 Bologna (Italy); Radiology Department, S. Orsola-Malpighi University Hospital, Via Massarenti 9, 40138 Bologna (Italy); Medical Physics Department, S. Orsola-Malpighi University Hospital, Via Massarenti 9, 40138 Bologna (Italy); Radiology Department, S. Orsola-Malpighi University Hospital, Via Massarenti 9, 40138 Bologna (Italy)
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.
Probabilistic calculation of dose commitment from uranium mill tailings
International Nuclear Information System (INIS)
The report discusses in a general way considerations of uncertainty in relation to probabilistic modelling. An example of a probabilistic calculation applied to the behaviour of uranium mill tailings is given
Energy Technology Data Exchange (ETDEWEB)
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.
Dose distribution calculation for in-vivo X-ray fluorescence scanning
Energy Technology Data Exchange (ETDEWEB)
Figueroa, R. G. [Universidad de la Frontera, Departamento de Ciencias Fisicas, Av. Francisco Salazar 1145, Temuco 4811230, Araucania (Chile); Lozano, E. [Instituto Nacional del Cancer, Unidad de Fisica Medica, Av. Profesor Zanartu 1010, Santiago (Chile); Valente, M., E-mail: figueror@ufro.cl [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Av. Ravadavia 1917, C1033AAJ, Buenos Aires (Argentina)
2013-08-01
In-vivo X-ray fluorescence constitutes a useful and accurate technique, worldwide established for constituent elementary distribution assessment. Actually, concentration distributions of arbitrary user-selected elements can be achieved along sample surface with the aim of identifying and simultaneously quantifying every constituent element. The method is based on the use of a collimated X-ray beam reaching the sample. However, one common drawback for considering the application of this technique for routine clinical examinations was the lack of information about associated dose delivery. This work presents a complete study of the dose distribution resulting from an in-vivo X-ray fluorescence scanning for quantifying biohazard materials on human hands. Absorbed dose has been estimated by means of dosimetric models specifically developed to this aim. In addition, complete dose distributions have been obtained by means of full radiation transport calculations in based on stochastic Monte Carlo techniques. A dedicated subroutine has been developed using the Penelope 2008 main code also integrated with dedicated programs -Mat Lab supported- for 3 dimensional dose distribution visualization. The obtained results show very good agreement between approximate analytical models and full descriptions by means of Monte Carlo simulations. (Author)
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.
Sensitivity of NTCP parameter values against a change of dose calculation algorithm
DEFF Research Database (Denmark)
Brink, Carsten; Berg, Martin; Nielsen, Morten
2007-01-01
predicted for a given treatment will in general depend on the algorithm. The purpose of this work is to test whether the optimal NTCP parameter values change significantly when the dose calculation algorithm is changed. The treatment plans for 17 breast cancer patients have retrospectively been recalculated......Optimization of radiation treatment planning requires estimations of the normal tissue complication probability (NTCP). A number of models exist that estimate NTCP from a calculated dose distribution. Since different dose calculation algorithms use different approximations the dose distributions...
International Nuclear Information System (INIS)
A method is described for determining an effective, depth dose consistent bremsstrahlung spectra for high-energy photon beams using depth dose curves measured in water. A simple, analytical model with three parameters, together with the nominal accelerating potential is used to characterise the bremsstrahlung spectra. The model is used to compute weights for depth dose curves from monoenergetic photons. These monoenergetic depth doses, calculated with the convolution method from Monte Carlo generated point spread functions (PSF), are added to yield the pure photon depth dose distribution. The parameters of the analytical spectrum model are determined using an iterative technique to minimise the difference between calculated and measured depth dose curves. The influence from contaminant electrons is determined from the difference between the calculated and the measured depth dose. (author)
Organ shielding and doses in Low-Earth orbit calculated for spherical and anthropomorphic phantoms
Matthiä, Daniel; Berger, Thomas; Reitz, Günther
2013-08-01
Humans in space are exposed to elevated levels of radiation compared to ground. Different sources contribute to the total exposure with galactic cosmic rays being the most important component. The application of numerical and anthropomorphic phantoms in simulations allows the estimation of dose rates from galactic cosmic rays in individual organs and whole body quantities such as the effective dose. The male and female reference phantoms defined by the International Commission on Radiological Protection and the hermaphrodite numerical RANDO phantom are voxel implementations of anthropomorphic phantoms and contain all organs relevant for radiation risk assessment. These anthropomorphic phantoms together with a spherical water phantom were used in this work to translate the mean shielding of organs in the different anthropomorphic voxel phantoms into positions in the spherical phantom. This relation allows using a water sphere as surrogate for the anthropomorphic phantoms in both simulations and measurements. Moreover, using spherical phantoms in the calculation of radiation exposure offers great advantages over anthropomorphic phantoms in terms of computational time. In this work, the mean shielding of organs in the different voxel phantoms exposed to isotropic irradiation is presented as well as the corresponding depth in a water sphere. Dose rates for Low-Earth orbit from galactic cosmic rays during solar minimum conditions were calculated using the different phantoms and are compared to the results for a spherical water phantom in combination with the mean organ shielding. For the spherical water phantom the impact of different aluminium shielding between 1 g/cm2 and 100 g/cm2 was calculated. The dose equivalent rates were used to estimate the effective dose rate.
Methodology for calculation of doses to man and implementation in Pandora
Energy Technology Data Exchange (ETDEWEB)
Avila, Rodolfo [Facilia AB, Bromma (Sweden); Bergstroem, Ulla [Swepro Project Management AB, Solna (Sweden)
2006-07-15
This report describes methods and data for calculation of doses to man to be used in safety assessments of repositories for nuclear fuel. The methods are based on the latest recommendations from the ICRP; the EU and the national radiation protection authorities. Equations are given for calculation of doses from ingestion of contaminated water and food, inhalation of contaminated air and external exposure from radionuclides in the ground. With the exception of the exposure from food ingestion, the equations are the same used in previous safety assessments. A general equation is suggested for estimation of the exposure from food ingestion, in which the annual demand of carbon is used instead of the annual ingestion of different food-stuffs, which was earlier applied. The report contains tables with recommended values for physiological characteristics such as water intake, food intake and inhalation rates, based on information summarised in an Appendix. Furthermore, tables are given with recommended age dependent dose conversion factors for ingestion and inhalation for a number of nuclides of interest for safety assessments. The most recently published dose conversion factors for external exposure from contaminated ground are also given. An overview of the implementation of the methodology in Pandora, which is the tool that SKB and Posiva currently use for biosphere modelling, is also provided. The work presented in the report is a result from a joint project commissioned by SKB and Posiva.
An analytic linear accelerator source model for GPU-based Monte Carlo dose calculations
Tian, Zhen; Li, Yongbao; Folkerts, Michael; Shi, Feng; Jiang, Steve B.; Jia, Xun
2015-10-01
dose difference within 1.7%. The maximum relative difference of output factors was within 0.5%. Over 98.5% passing rate was achieved in 3D gamma-index tests with 2%/2 mm criteria in both an IMRT prostate patient case and a head-and-neck case. These results demonstrated the efficacy of our model in terms of accurately representing a reference phase-space file. We have also tested the efficiency gain of our source model over our previously developed phase-space-let file source model. The overall efficiency of dose calculation was found to be improved by ~1.3-2.2 times in water and patient cases using our analytical model.
Kinetics and dose calculations of amikacin in the newborn
DEFF Research Database (Denmark)
Sardemann, H; Colding, H; Hendel, J;
1976-01-01
compartment model. The absorption was evaluated in 8 of the infants after intramuscular injection of 7.5 mg amikacin per kilogram of body weight. The absorption rate, estimated by the tmax, was significantly faster than reported in adults. The total body clearance and apparent volume of distribution were...... weight. The volume of distribution per kilogram was significantly greater than in adults. On the basis of the derived kinetic parameters, a dose schedule is presented. In 5 children there was a reasonable agreement between the measured and predicted serum levels....
Calculating integral dose using data exported from a commercial record and verify system.
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
佐藤, 薫; 遠藤 章; 斎藤 公明
2008-01-01
At the Japan Atomic Energy Agency, high-resolution five Japanese adult voxel phantoms have been constructed up to now to clarify the variation of organ doses due to the anatomical characteristics of Japanese. This report presents a complete set of conversion coefficients of organ doses and effective doses calculated for external photon exposure using five Japanese voxel phantoms. The calculated conversion coefficients are compared with those of Caucasian voxel phantoms and the recommended val...
International Nuclear Information System (INIS)
Due to secondary cosmic radiation (SCR), pilots and flight attendants receive elevated effective doses at flight altitudes. For this reason, since 2003 aircrew members are considered as occupationally exposed, in Germany. This work deals with the calculation of dose conversion coefficients (DCC) for protons, neutrons, electrons, positrons, photons and myons, which are crucial for estimation of effective dose from SCR. For the first time, calculations were performed combining Geant4 - a Monte Carlo code developed at CERN - with the voxel phantoms for the reference female and male published in 2008 by ICRP and ICRU. Furthermore, measurements of neutron fluence spectra - which contribute the major part to the effective dose of SCR - were carried out at the Environmental Research Station Schneefernerhaus (UFS) located at 2650 m above sea level nearby the Zugspitze mountain, Germany. These measured neutron spectra, and additionally available calculated spectra, were then folded with the DCC calculated in this work, and effective dose rates for different heights were calculated.
Sakamoto, Y
2002-01-01
In the prevention of nuclear disaster, there needs the information on the dose equivalent rate distribution inside and outside the site, and energy spectra. The three dimensional radiation transport calculation code is a useful tool for the site specific detailed analysis with the consideration of facility structures. It is important in the prediction of individual doses in the future countermeasure that the reliability of the evaluation methods of dose equivalent rate distribution and energy spectra by using of Monte Carlo radiation transport calculation code, and the factors which influence the dose equivalent rate distribution outside the site are confirmed. The reliability of radiation transport calculation code and the influence factors of dose equivalent rate distribution were examined through the analyses of critical accident at JCO's uranium processing plant occurred on September 30, 1999. The radiation transport calculations including the burn-up calculations were done by using of the structural info...
International Nuclear Information System (INIS)
A new method for estimating radiation doses to UK critical groups is proposed for discussion. Amongst others, the Food Standards Agency (FSA) and the Scottish Environment Protection Agency (SEPA) undertake surveillance of UK food and the environment as a check on the effect of discharges of radioactive wastes. Discharges in gaseous and liquid form are made under authorisation by the Environment Agency and SEPA under powers in the Radioactive Substance Act. Results of surveillance by the FSA and SEPA are published in the Radioactivity in Food and the Environment (RIFE) report series. In these reports, doses to critical groups are normally estimated separately for gaseous and liquid discharge pathways. Simple summation of these doses would tend to overestimate doses actually received. Three different methods of combining the effects of both types of discharge in an integrated assessment are considered and ranked according to their ease of application, transparency, scientific rigour and presentational issues. A single integrated assessment method is then chosen for further study. Doses are calculated for surveillance data for the calendar year 2000 and compared with those from the existing RIFE method
A new finite cloud method for calculating external exposure dose in a nuclear emergency
International Nuclear Information System (INIS)
A new finite cloud method (5/μ method) for calculating external exposure dose in a nuclear emergency is presented in this paper. The method calculates external exposure dose over a specially constructed three-dimensional columned space, whose underside center is the location of the receptor and underside radius and height are both five times mean free path of a gamma-photon. Then, the space is divided into many grid cells for integral to calculate external exposure dose (or dose rate). The calculation values of air external exposure dose rate conversion factors and air-absorbed dose rate conversion factors by the 5/μ method are accordant with the values presented in related references. Comparing with the discrete point approximation method (DPA) [USNRC, The MESORAD Dose Assessment Model. NUREG/CR-4000 Vol. 1, 1986] and the Nomogram method [USNRC, Nomogram for Evaluation of Doses from Finite Noble Gas Clouds, NUREG-0851, 1983], which are two traditional finite cloud methods for calculating external exposure dose, the 5/μ method has a distinct advantage of more fast calculation speed, which is very important in a nuclear emergency. What is more, the 5/μ method can be applied together with three-dimensional atmospheric dispersion models
A new finite cloud method for calculating external exposure dose in a nuclear emergency
Energy Technology Data Exchange (ETDEWEB)
Wang, X.Y.; Ling, Y.S. E-mail: lingyongsheng00@mails.tsinghua.edu.cn; Shi, Z.Q
2004-06-01
A new finite cloud method (5/{mu} method) for calculating external exposure dose in a nuclear emergency is presented in this paper. The method calculates external exposure dose over a specially constructed three-dimensional columned space, whose underside center is the location of the receptor and underside radius and height are both five times mean free path of a gamma-photon. Then, the space is divided into many grid cells for integral to calculate external exposure dose (or dose rate). The calculation values of air external exposure dose rate conversion factors and air-absorbed dose rate conversion factors by the 5/{mu} method are accordant with the values presented in related references. Comparing with the discrete point approximation method (DPA) [USNRC, The MESORAD Dose Assessment Model. NUREG/CR-4000 Vol. 1, 1986] and the Nomogram method [USNRC, Nomogram for Evaluation of Doses from Finite Noble Gas Clouds, NUREG-0851, 1983], which are two traditional finite cloud methods for calculating external exposure dose, the 5/{mu} method has a distinct advantage of more fast calculation speed, which is very important in a nuclear emergency. What is more, the 5/{mu} method can be applied together with three-dimensional atmospheric dispersion models.
The calculation, presentation and use of collective doses for routine discharges
International Nuclear Information System (INIS)
Over recent decades concerns have been expressed about the way collective doses have been used. In particular, there is general agreement that using the fully aggregated collective dose masks a lot of useful information on levels of individual dose and their distribution over space and time, which decision makers may consider important. The International Commission on Radiological Protection has suggested a 'collective dose matrix' approach as a solution to this. A study has been carried out to explore some of the issues involved in the development and use of such matrices. In particular, practical issues regarding the disaggregation of collective dose in relation to individual dose rates and the temporal and spatial distribution of exposures have been addressed. Calculations have been undertaken to illustrate ways in which the estimated collective dose from routine discharges can be broken down. The nuclear site chosen was the Sellafield reprocessing plant but additional calculations were also undertaken for the Cap de La Hague reprocessing plant for comparative purposes. It was found that useful information on the temporal and spatial elements of collective doses can be obtained and that per-caput doses can be used to give an indication of the likely individual doses that make up the collective dose. At long times following discharges of radionuclides to the environment doses due to global circulation will dominate the collective dose and there is likely to be little requirement for obtaining information on individual dose distributions. (author)
Energy Technology Data Exchange (ETDEWEB)
Grassberger, C; Daartz, J; Dowdell, S; Ruggieri, T; Sharp, G; Paganetti, H [Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States)
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.
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
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
International Nuclear Information System (INIS)
This report presents a complete set of conversion coefficients of organ doses and effective doses calculated for external photon exposure using five Japanese adult voxel phantoms developed at the Japan Atomic Energy Agency (JAEA). At the JAEA, high-resolution Japanese voxel phantoms have been developed to clarify the variation of organ doses due to the anatomical characteristics of Japanese, and three male phantoms (JM, JM2 and Otoko) and two female phantoms (JF and Onago) have been constructed up to now. The conversion coefficients of organ doses and effective doses for the five voxel phantoms have been calculated for six kinds of idealized irradiation geometries from monoenergetic photons ranging from 0.01 to 10 MeV using EGS4, a Monte Carlo code for the simulation of coupled electron-photon transport. The dose conversion coefficients are given as absorbed dose and effective dose per unit air-kerma free-in-air, and are presented in tables and figures. The calculated dose conversion coefficients are compared with those of voxel phantoms based on the Caucasian and the recommended values in ICRP74 in order to discuss (1) variation of organ dose due to the body size and individual anatomy, such as position and shape of organs, and (2) effect of posture on organ doses. The present report provides valuable data to study the influence of the body characteristics of Japanese upon the organ doses and to discuss developing reference Japanese and Asian phantoms. (author)
International Nuclear Information System (INIS)
The comparatively high dose and increasing frequency of computed tomography (CT) examinations have spurred the development of techniques for reducing radiation dose to imaging patients. Among these is the application of tube current modulation (TCM), which can be applied either longitudinally along the body or rotationally along the body, or both. Existing computational models for calculating dose from CT examinations do not include TCM techniques. Dose calculations using Monte Carlo methods have been previously prepared for constant-current rotational exposures at various positions along the body and for the principle exposure projections for several sets of computational phantoms, including adult male and female and pregnant patients. Dose calculations from CT scans with TCM are prepared by appropriately weighting the existing dose data. Longitudinal TCM doses can be obtained by weighting the dose at the z-axis scan position by the relative tube current at that position. Rotational TCM doses are weighted using the relative organ doses from the principle projections as a function of the current at the rotational angle. Significant dose reductions of 15% to 25% to fetal tissues are found from simulations of longitudinal TCM schemes to pregnant patients of different gestational ages. Weighting factors for each organ in rotational TCM schemes applied to adult male and female patients have also been found. As the application of TCM techniques becomes more prevalent, the need for including TCM in CT dose estimates will necessarily increase. (author)
Calculation of multi-dimensional dose distribution in medium due to proton beam incidence
International Nuclear Information System (INIS)
The method of analyzing the multi-dimensional dose distribution in a medium due to proton beam incidence is presented to obtain the reliable and simplified method from clinical viewpoint, especially for the medical treatment of cancer. The heavy ion beam being taken out of an accelerator has to be adjusted to fit cancer location and size, utilizing a modified range modulator, a ridge filter, a bolus and a special scanning apparatus. The precise calculation of multi-dimensional dose distribution of proton beam is needed to fit treatment to a limit part. The analytical formulas consist of those for the fluence distribution in a medium, the divergence of flying range, the energy distribution itself, the dose distribution in side direction and the two-dimensional dose distribution. The fluence distribution in polystyrene in case of the protons with incident energy of 40 and 60 MeV, the energy distribution of protons at the position of a Bragg peak for various values of incident energy, the depth dose distribution in polystyrene in case of the protons with incident energy of 40 and 60 MeV and average energy of 100 MeV, the proton fluence and dose distribution as functions of depth for the incident average energy of 250 MeV, the statistically estimated percentage errors in the proton fluence and dose distribution, the estimated minimum detectable tumor thickness as a function of the number of incident protons for the different incident spectra with average energy of 250 MeV, the isodose distribution in a plane containing the central axis in case of the incident proton beam of 3 mm diameter and 40 MeV and so on are presented as the analytical results, and they are evaluated. (Nakai, Y.)
Evaluation of on-board kV cone beam CT (CBCT)-based dose calculation
Yang, Yong; Schreibmann, Eduard; Li, Tianfang; Wang, Chuang; Xing, Lei
2007-02-01
significant fluctuation was observed in the calibration over the period of 8 weeks. For the static phantom, the doses computed based on pCT and CBCT agreed to within 1%. A notable difference in CBCT- and pCT-based dose distributions was found for the motion phantom due to the motion artefacts which appeared in the CBCT images (the maximum discrepancy was found to be ~3.0% in the high dose region). The motion artefacts-induced dosimetric inaccuracy was also observed in the lung patient study. For the prostate cases, the mCBCT- and CBCT-based dose calculations yielded very close results (phantom data, it is concluded that the CBCT can be employed directly for dose calculation for a disease site such as the prostate, where there is little motion artefact. In the prostate case study, we also noted a large discrepancy between the original treatment plan and the CBCT (or mCBCT)-based calculation, suggesting the importance of inter-fractional organ movement and the need for adaptive therapy to compensate for the anatomical changes in the future. Part of this work was presented in 2006 Annual Meeting of American Association of Physicists in Medicine.
Advantages of mesh tallying in MCNPX for 3D dose calculations in radiotherapy
International Nuclear Information System (INIS)
The energy deposition mesh tally option of MCNPX Monte Carlo code is very useful for 3-Dimentional (3D) dose calculations. In this study, the 3D dose calculation was done for CT-based Monte Carlo treatment planning in which the energy deposition mesh tally were superimposed on merged voxel model. The results were compared with those of obtained from the common energy deposition (*F8) tally method for all cells of non-merged voxel model. The results of these two tallies and their respective computational times are compared, and the advantages of the proposed method are discussed. For this purpose, a graphical user interface (GUI) application was developed for reading CT slice data of patient, creating voxelized model of patient, optionally merging adjacent cells with the same material to reduce the total number of cells, reading beam configuration from commercial treatment planning system transferred in DICOM-RT format, and showing the isodose distribution on the CT images. To compare the results of Monte Carlo calculated and TiGRT planning system (LinaTech LLC, USA), treatment head of the Siemens ONCOR Impression accelerator was also simulated and the phase-space data on the scoring plane just above the Y-jaws was created and used. The results for a real prostate intensity-modulated radiation therapy (IMRT) plan showed that the proposed method was fivefold faster while the precision was almost the same. (author)
Bourguignon, Laurent; Goutelle, Sylvain; Gérard, Cécile; Guillermet, Anne; Burdin de Saint Martin, Julie; Maire, Pascal; Ducher, Michel
2009-01-01
The use of amikacin is difficult because of its toxicity and its pharmacokinetic variability. This variability is almost ignored in adult standard dosage regimens since only the weight is used in the dose calculation. Our objective is to test if the pharmacokinetic of amikacin can be regarded as homogenous, and if the method for calculating the dose according to patients' weight is appropriate. From a cohort of 580 patients, five groups of patients were created by statistical data partitioning. A population pharmacokinetic analysis was performed in each group. The adult population is not homogeneous in term of pharmacokinetics. The doses required to achieve a maximum concentration of 60 mg/L are strongly different (585 to 1507 mg) between groups. The exclusive use of the weight to calculate the dose of amikacine appears inappropriate for 80% of the patients, showing the limits of the formulae for calculating doses of aminoglycosides.
Wang, Lilie; Ding, George X.
2014-07-01
The out-of-field dose can be clinically important as it relates to the dose of the organ-at-risk, although the accuracy of its calculation in commercial radiotherapy treatment planning systems (TPSs) receives less attention. This study evaluates the uncertainties of out-of-field dose calculated with a model based dose calculation algorithm, anisotropic analytical algorithm (AAA), implemented in a commercial radiotherapy TPS, Varian Eclipse V10, by using Monte Carlo (MC) simulations, in which the entire accelerator head is modeled including the multi-leaf collimators. The MC calculated out-of-field doses were validated by experimental measurements. The dose calculations were performed in a water phantom as well as CT based patient geometries and both static and highly modulated intensity-modulated radiation therapy (IMRT) fields were evaluated. We compared the calculated out-of-field doses, defined as lower than 5% of the prescription dose, in four H&N cancer patients and two lung cancer patients treated with volumetric modulated arc therapy (VMAT) and IMRT techniques. The results show that the discrepancy of calculated out-of-field dose profiles between AAA and the MC depends on the depth and is generally less than 1% for in water phantom comparisons and in CT based patient dose calculations for static field and IMRT. In cases of VMAT plans, the difference between AAA and MC is <0.5%. The clinical impact resulting from the error on the calculated organ doses were analyzed by using dose-volume histograms. Although the AAA algorithm significantly underestimated the out-of-field doses, the clinical impact on the calculated organ doses in out-of-field regions may not be significant in practice due to very low out-of-field doses relative to the target dose.
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-07-01
The guide sets out the mathematical definitions and principles involved in the calculation of the equivalent dose and the effective dose, and the instructions concerning the application of the maximum values of these quantities. further, for monitoring the dose caused by internal radiation, the guide defines the limits derived from annual dose limits (the Annual Limit on Intake and the Derived Air Concentration). Finally, the guide defines the operational quantities to be used in estimating the equivalent dose and the effective dose, and also sets out the definitions of some other quantities and concepts to be used in monitoring radiation exposure. The guide does not include the calculation of patient doses carried out for the purposes of quality assurance.
DEFF Research Database (Denmark)
Grandjean, Philippe; Budtz-Joergensen, Esben
2013-01-01
BACKGROUND: Immune suppression may be a critical effect associated with exposure to perfluorinated compounds (PFCs), as indicated by recent data on vaccine antibody responses in children. Therefore, this information may be crucial when deciding on exposure limits. METHODS: Results obtained from...... follow-up of a Faroese birth cohort were used. Serum-PFC concentrations were measured at age 5 years, and serum antibody concentrations against tetanus and diphtheria toxoids were obtained at ages 7 years. Benchmark dose results were calculated in terms of serum concentrations for 431 children...
Dual-energy CT-based material extraction for tissue segmentation in Monte Carlo dose calculations
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.
Application of Monte Carlo method for dose calculation in thyroid follicle
International Nuclear Information System (INIS)
The Monte Carlo method is an important tool to simulate radioactive particles interaction with biologic medium. The principal advantage of the method when compared with deterministic methods is the ability to simulate a complex geometry. Several computational codes use the Monte Carlo method to simulate the particles transport and they have the capacity to simulate energy deposition in models of organs and/or tissues, as well models of cells of human body. Thus, the calculation of the absorbed dose to thyroid's follicles (compound of colloid and follicles' cells) have a fundamental importance to dosimetry, because these cells are radiosensitive due to ionizing radiation exposition, in particular, exposition due to radioisotopes of iodine, because a great amount of radioiodine may be released into the environment in case of a nuclear accidents. In this case, the goal of this work was use the code of particles transport MNCP4C to calculate absorbed doses in models of thyroid's follicles, for Auger electrons, internal conversion electrons and beta particles, by iodine-131 and short-lived iodines (131, 132, 133, 134 e 135), with diameters varying from 30 to 500 μm. The results obtained from simulation with the MCNP4C code shown an average percentage of the 25% of total absorbed dose by colloid to iodine- 131 and 75% to short-lived iodine's. For follicular cells, this percentage was of 13% to iodine-131 and 87% to short-lived iodine's. The contributions from particles with low energies, like Auger and internal conversion electrons should not be neglected, to assessment the absorbed dose in cellular level. Agglomerative hierarchical clustering was used to compare doses obtained by codes MCNP4C, EPOTRAN, EGS4 and by deterministic methods. (author)
Energy Technology Data Exchange (ETDEWEB)
Landry, Guillaume; Reniers, Brigitte; Pignol, Jean-Philippe; Beaulieu, Luc; Verhaegen, Frank [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, Universite Laval, CHUQ Pavillon L' Hotel-Dieu de Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d' Optique, Universite Laval, Quebec G1K 7P4 (Canada); Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands) and Department of Oncology, McGill University, Montreal General Hospital, Montreal, Quebec H3G 1A4 (Canada)
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
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Kamboj, S.; Yu, C.; Rabovsky, J. (Environmental Science Division); (USDOE)
2011-08-02
The purpose of this report is to evaluate the potential dose distribution resulting from surface radioactivity, using occupational radiation exposure scenarios. The surface radioactivity clearance values considered in this analysis may ultimately replace those currently specified in the U.S. Department of Energy (DOE) requirements and guidance for radiological protection of workers, the public and the environment. The surface contamination values apply to radioactive contamination deposited on a surface (i.e., not incorporated into the interior of the material). For these calculations, the dose coefficients for intake of radionuclides were taken from ICRP Publication 68 (ICRP 1994), and external exposure dose coefficients were taken from the compact disc (CD) that accompanied Federal Guidance Report (FGR) 13 (Eckerman et al. 1999). The ICRP Publication 68 dose coefficients were based on ICRP Publication 60 (ICRP 1990) and were used specifically for worker dose calculations. The calculated dose in this analysis is the 'effective dose' (ED), rather than the 'effective dose equivalent' (EDE).
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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
Comparison of CT number calibration techniques for CBCT-based dose calculation
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Dunlop, Alex [The Royal Marsden NHS Foundation Trust, Joint Department of Physics, Institute of Cancer Research, London (United Kingdom); The Royal Marsden Hospital, Sutton, Surrey, Downs Road (United Kingdom); McQuaid, Dualta; Nill, Simeon; Hansen, Vibeke N.; Oelfke, Uwe [The Royal Marsden NHS Foundation Trust, Joint Department of Physics, Institute of Cancer Research, London (United Kingdom); Murray, Julia; Bhide, Shreerang; Harrington, Kevin [The Royal Marsden Hospital, Sutton, Surrey, Downs Road (United Kingdom); The Institute of Cancer Research, London (United Kingdom); Poludniowski, Gavin [Karolinska University Hospital, Department of Medical Physics, Stockholm (Sweden); Nutting, Christopher [The Institute of Cancer Research, London (United Kingdom); Newbold, Kate [The Royal Marsden Hospital, Sutton, Surrey, Downs Road (United Kingdom)
2015-12-15
The aim of this work was to compare and validate various computed tomography (CT) number calibration techniques with respect to cone beam CT (CBCT) dose calculation accuracy. CBCT dose calculation accuracy was assessed for pelvic, lung, and head and neck (H and N) treatment sites for two approaches: (1) physics-based scatter correction methods (CBCT{sub r}); (2) density override approaches including assigning water density to the entire CBCT (W), assignment of either water or bone density (WB), and assignment of either water or lung density (WL). Methods for CBCT density assignment within a commercially available treatment planning system (RS{sub auto}), where CBCT voxels are binned into six density levels, were assessed and validated. Dose-difference maps and dose-volume statistics were used to compare the CBCT dose distributions with the ground truth of a planning CT acquired the same day as the CBCT. For pelvic cases, all CTN calibration methods resulted in average dose-volume deviations below 1.5 %. RS{sub auto} provided larger than average errors for pelvic treatments for patients with large amounts of adipose tissue. For H and N cases, all CTN calibration methods resulted in average dose-volume differences below 1.0 % with CBCT{sub r} (0.5 %) and RS{sub auto} (0.6 %) performing best. For lung cases, WL and RS{sub auto} methods generated dose distributions most similar to the ground truth. The RS{sub auto} density override approach is an attractive option for CTN adjustments for a variety of anatomical sites. RS{sub auto} methods were validated, resulting in dose calculations that were consistent with those calculated on diagnostic-quality CT images, for CBCT images acquired of the lung, for patients receiving pelvic RT in cases without excess adipose tissue, and for H and N cases. (orig.) [German] Ziel dieser Arbeit ist der Vergleich und die Validierung mehrerer CT-Kalibrierungsmethoden zur Dosisberechnung auf der Grundlage von Kegelstrahlcomputertomographie
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Habib, B.; Poumarede, B.; Tola, F.; Barthe, J. [CEA, LIST, Dept Technol Capteur et Signal, F-91191 Gif Sur Yvette, (France)
2010-07-01
The aim of the present study is to demonstrate the potential of accelerated dose calculations, using the fast Monte Carlo (MC) code referred to as PENFAST, rather than the conventional MC code PENELOPE, without losing accuracy in the computed dose. For this purpose, experimental measurements of dose distributions in homogeneous and inhomogeneous phantoms were compared with simulated results using both PENELOPE and PENFAST. The simulations and experiments were performed using a Saturne 43 linac operated at 12 MV (photons), and at 18 MeV (electrons). Pre-calculated phase space files (PSFs) were used as input data to both the PENELOPE and PENFAST dose simulations. Since depth-dose and dose profile comparisons between simulations and measurements in water were found to be in good agreement (within {+-} 1% to 1 mm), the PSF calculation is considered to have been validated. In addition, measured dose distributions were compared to simulated results in a set of clinically relevant, inhomogeneous phantoms, consisting of lung and bone heterogeneities in a water tank. In general, the PENFAST results agree to within a 1% to 1 mm difference with those produced by PENELOPE, and to within a 2% to 2 mm difference with measured values. Our study thus provides a pre-clinical validation of the PENFAST code. It also demonstrates that PENFAST provides accurate results for both photon and electron beams, equivalent to those obtained with PENELOPE. CPU time comparisons between both MC codes show that PENFAST is generally about 9-21 times faster than PENELOPE. (authors)
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This report considers the contribution from scattered radiation to the dose to organs and tissues which lie outside the useful therapy beams. The results presented are the product of Monte Carlo studies used to determine the tissue doses due to internal scattering of the useful beams only. General cases are calculated in which central target volumes in the trunk are treated with 10 x 14 cm2 and 14 x 14 cm2 fields from 200 kV, Co-60, 8 MV and 25 MV therapy equipment. Target volumes in the neck are considered to be treated with 5 x 5 cm2 fields. Different treatment plans are calculated including rotational therapy. Also two specific cases are more fully analysed, namely for Ankylosing Spondylitis and central abdomen malignant disease in the region of the head of the pancreas. The calculated organ doses are presented in tables as a percentage of the target volume dose. (orig.)
Development of a GPU-based Monte Carlo dose calculation code for coupled electron-photon transport
Jia, Xun; Sempau, Josep; Choi, Dongju; Majumdar, Amitava; Jiang, Steve B
2009-01-01
Monte Carlo simulation is the most accurate method for absorbed dose calculations in radiotherapy. Its efficiency still requires improvement for routine clinical applications, especially for online adaptive radiotherapy. In this paper, we report our recent development on a GPU-based Monte Carlo dose calculation code for coupled electron-photon transport. We have implemented the Dose Planning Method (DPM) Monte Carlo dose calculation package (Sempau et al, Phys. Med. Biol., 45(2000)2263-2291) on GPU architecture under CUDA platform. The implementation has been tested with respect to the original sequential DPM code on CPU in two cases. Our results demonstrate the adequate accuracy of the GPU implementation for both electron and photon beams in radiotherapy energy range. A speed up factor of 4.5 and 5.5 times have been observed for electron and photon testing cases, respectively, using an NVIDIA Tesla C1060 GPU card against a 2.27GHz Intel Xeon CPU processor .
Calculation and analysis of photon dose equivalent distributions in the ICRU sphere
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Detailed dose equivalent distributions have been calculated in the ICRU sphere by Monte Carlo methods for photons in the energy range 0.010 - 10.0 MeV using the kerma approximation, with statistical accuracy generally better than +- 1%. Results are presented as depth-dose distributions along the principal axis and other selected axes and as isodose distributions, for parallel unidirectional, parallel opposed, planar rotational, planar isotropic and spatially isotropic irradiation. Various DE quantities are discussed and their numerical values presented as functions of photon energy. Six appendices are included which discuss (I.) conversion factors for different basic normalisation quantities, (II.) briefly the Monte Carlo procedure used, (III.) the meaning of kerma and the kerma approximation, (IV.) a comparison of the work presented in this report and the calculations of Dimbylow in 1983, (V.) a test experiment using a 30 cm spherical phantom, (VI.) the results of backscatter measurements and calculations using a 30 cm spherical phantom and cubic phantoms. (orig.)
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Calculations with the quadratic lineal model for medium rate using the equation dose-effect. Several calculations for system of low dose rate brachytherapy plus teletherapy, calculations for brachytherapy with medium dose rate together with teletherapy, dose for fraction and the one numbers of fractions in medium rate
Dose and shielding calculation of galactic cosmic ray using FLUKA Mont Carlo code
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Jalali, Hamide B. [Physics Department, University of Qom, Qom (Iran); Raisali, Golamreza; Babazade, Alireza [Radiation Applications Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, Tehran (Iran); Feghhi, Amirhosein [Physics and Nuclear Engineering Department, Amirkabir University, Tehran (Iran)
2009-07-01
Astronauts' exposure to space radiation is a limiting factor for long-term missions. Therefore shielding is a critical issue in space mission success. In this work the FLUKA Monte Carlo code has been coupled with simple models of the spacecraft and equivalent phantom to calculate skin averaged doses due to exposure to Galactic Cosmic Rays (GCR) beyond various thicknesses of aluminium and polyethylene shields. Simulations have been performed for the most abundant elements including H, He, C and Fe ions. The spectra of these ions have been taken from Badhwar-O'Neill's model, and LET distribution of the ions and electrons calculated using SRIM and ESTAR computer programs, respectively. It has been observed that GCR absorbed dose behind the shields remained approximately constant with increasing shield thicknesses, but dose equivalent shows a slight decrease. It is also found that although polyethylene is a more effective GCR shield than aluminum as indicated in the results of similar investigations, but the practical thicknesses of polyethylene are still insufficient to shield high energy GCR ions encountered in long-term space missions.
Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections
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Jones, Bernard L., E-mail: bernard.jones@ucdenver.edu; Westerly, David; Miften, Moyed [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States)
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
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Koeck, J.; Stieler, F.; Fleckenstein, J.; Wenz, F.; Lohr, F. [Universitaetsmedizin Mannheim, Heidelberg Univ., Mannheim (Germany). Klinik fuer Strahlentherapie und Radioonkologie; Abo-Madyan, Y. [Universitaetsmedizin Mannheim, Heidelberg Univ., Mannheim (Germany). Klinik fuer Strahlentherapie und Radioonkologie; Cairo Univ. (Egypt). Dept. of Radiation Oncology; Eich, H.T. [Muenster Univ. (Germany). Dept. of Radiation Oncology; Kriz, J.; Mueller, R.P. [Klinikum der Universitaet zu Koeln (Germany). Universitaetsklinik und Poliklinik fuer Strahlentherapie
2012-08-15
Background and purpose: Conventional algorithms show uncertainties in dose calculation already for three-dimensional conformal radiotherapy (3D-CRT). Intensity-modulated radiotherapy (IMRT) might even increase these. We wanted to assess differences in dose distribution for pencil beam (PB), collapsed cone (CC), and Monte Carlo (MC) algorithm for both 3D-CRT and IMRT in patients with mediastinal Hodgkin lymphoma. Patients and methods: Based on 20 computed tomograph (CT) datasets of patients with mediastinal Hodgkin lymphoma, we created treatment plans according to the guidelines of the German Hodgkin Study Group (GHSG) with PB and CC algorithm for 3D-CRT and with PB and MC algorithm for IMRT. Doses were compared for planning target volume (PTV) and organs at risk. Results: For 3D-CRT, PB overestimated PTV{sub 95} and V{sub 20} of the lung by 6.9% and 3.3% and underestimated V{sub 10} of the lung by 5.8%, compared to the CC algorithm. For IMRT, PB overestimated PTV{sub 95}, V{sub 20} of the lung, V{sub 25} of the heart and V{sub 10} of the female left/right breast by 8.1%, 25.8%, 14.0% and 43.6%/189.1%, and underestimated V{sub 10} of the lung, V{sub 4} of the heart and V{sub 4} of the female left/right breast by 6.3%, 6.8% and 23.2%/15.6%, compared to MC. Conclusion: The PB algorithm underestimates low doses to the organs at risk and overestimates dose to PTV and high doses to the organs at risk. For 3D-CRT, a well-modeled PB algorithm is clinically acceptable; for IMRT planning, however, an advanced algorithm such as CC or MC should be used at least for part of the plan optimization. (orig.)
Comparison between Acuros XB and Brainlab Monte Carlo algorithms for photon dose calculation
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Misslbeck, M.; Kneschaurek, P. [Klinikum rechts der Isar der Technischen Univ. Muenchen (Germany). Klinik und Poliklinik fuer Strahlentherapie und Radiologische Onkologie
2012-07-15
Purpose: The Acuros {sup registered} XB dose calculation algorithm by Varian and the Monte Carlo algorithm XVMC by Brainlab were compared with each other and with the well-established AAA algorithm, which is also from Varian. Methods: First, square fields to two different artificial phantoms were applied: (1) a 'slab phantom' with a 3 cm water layer, followed by a 2 cm bone layer, a 7 cm lung layer, and another 18 cm water layer and (2) a 'lung phantom' with water surrounding an eccentric lung block. For the slab phantom, depth-dose curves along central beam axis were compared. The lung phantom was used to compare profiles at depths of 6 and 14 cm. As clinical cases, the CTs of three different patients were used. The original AAA plans with all three algorithms using open fields were recalculated. Results: There were only minor differences between Acuros and XVMC in all artificial phantom depth doses and profiles; however, this was different for AAA, which had deviations of up to 13% in depth dose and a few percent for profiles in the lung phantom. These deviations did not translate into the clinical cases, where the dose-volume histograms of all algorithms were close to each other for open fields. Conclusion: Only within artificial phantoms with clearly separated layers of simulated tissue does AAA show differences at layer boundaries compared to XVMC or Acuros. In real patient CTs, these differences in the dose-volume histogram of the planning target volume were not observed. (orig.)
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Ehrbar, Stefanie; Lang, Stephanie; Stieb, Sonja; Riesterer, Oliver; Stark, Luisa Sabrina; Guckenberger, Matthias; Kloeck, Stephan [University Hospital Zuerich (Switzerland). Dept. of Radiation Oncology
2016-05-01
Purpose: Respiratory motion is a non-negligible source of uncertainty in radiotherapy. A common approach is to delineate the target volume in all respiratory phases (ITV) and to calculate a treatment plan using the average reconstruction of the four-dimensional computed tomography (4DCT) scans. In this study the extent of the interplay effect caused by interaction between dynamic dose delivery and respiratory tumor motion, as well as other motion effects were investigated. These effects are often ignored when the ITV concept is used. Methods and Materials: Nine previously treated patients with in ten abdominal or thoracic cancer lesions (3 liver, 3 adrenal glands and 4 lung lesions) were selected for this planning study. For all patients, phase-sorted respiration-correlated 4DCT scans were taken, and volumetric modulated arc therapy (VMAT) treatments were planned using the ITV concept. Margins from ITV to planning target volume (PTV) of 3-10 mm were used. Plans were optimized and dose distributions were calculated on the average reconstruction of the 4DCT. 4D dose distributions were calculated to evaluate motion effects, caused by the interference of dynamic treatment delivery with respiratory tumor motion and inhomogeneously planned target dose. These calculations were performed on the phase-sorted CT series with a respiration-correlated assignment of the treatment plan's monitor units (MU) to the respiration phases of the 4DCT. The 4D dose was accumulated with rigid as well as deformable registrations of the CT series and compared to the original 3D dose distribution. Maximum, minimum and mean doses to ITV and PTV, and maximum or mean doses to organs at risk (OAR), were compared after rigid accumulation. The dose variation in the gross tumor volume (GTV) was compared after deformable registration. Results: Using rigid registrations, variations in the investigated dose parameters between 3D and 4D dose calculations were found to be within -2.1% to 1.4% for
Independent dose calculation in IMRT for the Tps Iplan using the Clarkson modified integral
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Intensity-Modulated Radiation Therapy (IMRT) treatments require a quality assurance (Q A) specific patient before delivery. These controls include the experimental verification in dose phantom of the total plan as well as dose distributions. The use of independent dose calculation (IDC) is used in 3D-Crt treatments; however its application in IMRT requires the implementation of an algorithm that allows considering a non-uniform intensity beam. The purpose of this work was to develop IDC software in IMRT with MLC using the algorithm proposed by Kung (Kung et al. 2000). The software was done using Matlab programming. The Clarkson modified integral was implemented on each flowing, applying concentric rings for the dose determination. From the integral of each field was calculated the dose anywhere. One time finished a planning; all data are exported to a phantom where a Q A plan is generated. On this is calculated the half dose in a representative volume of the ionization chamber and the dose at the center of it. Until now 230 IMRT planning were analyzed carried out ??in the treatment planning system (Tps) Iplan. For each one of them Q A plan was generated, were calculated and compared calculated dose with the Tps, IDC system and measurement with ionization chamber. The average difference between measured and calculated dose with the IDC system was 0.4% ± 2.2% [-6.8%, 6.4%]. The difference between the measured and the calculated doses by the pencil-beam algorithm (Pb) of Tps was 2.6% ± 1.41% [-2.0%, 5.6%] and with the Monte Carlo algorithm was 0.4% ± 1.5% [-4.9%, 3.7%]. The differences of the carried out software are comparable to the obtained with the ionization chamber and Tps in Monte Carlo mode. (author)
SU-E-T-465: Dose Calculation Method for Dynamic Tumor Tracking Using a Gimbal-Mounted Linac
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Sugimoto, S; Inoue, T; Kurokawa, C; Usui, K; Sasai, K [Juntendo University, Bunkyo, Tokyo, JP (Japan); Utsunomiya, S [Niigata University, Niigata, Nigata, JP (Japan); Ebe, K [Joetsu General Hospital, Joetsu, Niigata, JP (Japan)
2014-06-01
Purpose: Dynamic tumor tracking using the gimbal-mounted linac (Vero4DRT, Mitsubishi Heavy Industries, Ltd., Japan) has been available when respiratory motion is significant. The irradiation accuracy of the dynamic tumor tracking has been reported to be excellent. In addition to the irradiation accuracy, a fast and accurate dose calculation algorithm is needed to validate the dose distribution in the presence of respiratory motion because the multiple phases of it have to be considered. A modification of dose calculation algorithm is necessary for the gimbal-mounted linac due to the degrees of freedom of gimbal swing. The dose calculation algorithm for the gimbal motion was implemented using the linear transformation between coordinate systems. Methods: The linear transformation matrices between the coordinate systems with and without gimbal swings were constructed using the combination of translation and rotation matrices. The coordinate system where the radiation source is at the origin and the beam axis along the z axis was adopted. The transformation can be divided into the translation from the radiation source to the gimbal rotation center, the two rotations around the center relating to the gimbal swings, and the translation from the gimbal center to the radiation source. After operating the transformation matrix to the phantom or patient image, the dose calculation can be performed as the no gimbal swing. The algorithm was implemented in the treatment planning system, PlanUNC (University of North Carolina, NC). The convolution/superposition algorithm was used. The dose calculations with and without gimbal swings were performed for the 3 × 3 cm{sup 2} field with the grid size of 5 mm. Results: The calculation time was about 3 minutes per beam. No significant additional time due to the gimbal swing was observed. Conclusions: The dose calculation algorithm for the finite gimbal swing was implemented. The calculation time was moderate.
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.
Poster — Thur Eve — 14: Improving Tissue Segmentation for Monte Carlo Dose Calculation using DECT
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Di Salvio, A.; Bedwani, S.; Carrier, J-F. [Centre hospitalier de l' Université de Montréal (Canada); Bouchard, H. [National Physics Laboratory, Teddington (United Kingdom)
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.
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Fogliata, Antonella [Oncology Inst. of Southern Switzerland, Medical Physics Unit, Bellinzona (Switzerland)], e-mail: Antonella.Fogliata-Cozzi@eoc.ch; Scorsetti, Marta; Navarria, Piera [IRCCS Instituto Clinico Humanitas, Radiation Oncology, Rozzano, Milan (Italy)] [and others
2013-04-15
Background: To appraise the potential of volumetric modulated arc therapy (VMAT, RapidArc) and proton beams to simultaneously achieve target coverage and enhanced sparing of bone tissue in the treatment of soft-tissue sarcoma with adequate target coverage. Material and methods: Ten patients presenting with soft-tissue sarcoma of the leg were collected for the study. Dose was prescribed to 66.5 Gy in 25 fractions to the planning target volume (PTV) while significant maximum dose to the bone was constrained to 50 Gy. Plans were optimised according to the RapidArc technique with 6 MV photon beams or for intensity modulated protons. RapidArc photon plans were computed with: 1) AAA; 2) Acuros XB as dose to medium; and 3) Acuros XB as dose to water. Results: All plans acceptably met the criteria of target coverage (V{sub 95%} >90-95%) and bone sparing (D{sub 1cm}{sup 3} <50 Gy). Significantly higher PTV dose homogeneity was found for proton plans. Near-to-maximum dose to bone was similar for RapidArc and protons, while volume receiving medium/low dose levels was minimised with protons. Similar results were obtained for the remaining normal tissue. Dose distributions calculated with the dose to water option resulted 5% higher than corresponding ones computed as dose to medium. Conclusion: High plan quality was demonstrated for both VMAT and proton techniques when applied to soft-tissue sarcoma.
DEFF Research Database (Denmark)
Knöös, Tommy; Wieslander, Elinore; Cozzi, Luca;
2006-01-01
correction-based equivalent path length algorithms to model-based algorithms. These were divided into two groups based on how changes in electron transport are accounted for ((a) not considered and (b) considered). Increasing the complexity from the relatively homogeneous pelvic region to the very...... to the fields. A Monte Carlo calculated algorithm input data set and a benchmark set for a virtual linear accelerator have been produced which have facilitated the analysis and interpretation of the results. The more sophisticated models in the type b group exhibit changes in both absorbed dose and its...
Monte Carlo 20 and 45 MeV Bremsstrahlung and dose-reduction calculations
International Nuclear Information System (INIS)
The SANDYL electron-photon coupled Monte Carlo code has been compared with previously published experimental bremsstrahlung data at 20.9 MeV electron energy. The code was then used to calculate forward-directed spectra, angular distributions and dose-reduction factors for three practical configurations. These are: 20 MeV electrons incident on 1 mm of W + 59 mm of Be, 45 MeV electrons of 1 mm of W and 45 MeV electrons on 1 mm of W + 147 mm of Be. The application of these results to flash radiography is discussed. 7 references, 12 figures, 1 table
Detriment calculations resulting from occupational radiation exposures in Egypt
International Nuclear Information System (INIS)
The application of the nominal probability coefficient to evaluate the detriment after the annual occupational exposures of workers from radiation sources and radioactive material have been calculated for workers in medical practices, industrial applications, atomic energy activities and those involved in exploration and mining of radioactive ores and phosphates. The aim of detriment calculations is to provide a foresight for the future occurrence of stochastic effects among the exposed workers. The calculated detriment can be classified into three classes. The first includes workers in diagnostic radiology and atomic energy activities who received the higher doses and consequently represent the higher detriment. The second class comprises workers in radiotherapy and nuclear medicine whose detriment is for times lesser than that of the first class. The third one concerns workers in industrial applications and in exploration and mining of radioactive ores and phosphates, their detriments ten times lesser than that of the second class. The occupational radiation doses are endorsed by the united nation scientific committee on efects of atomic radiation (UNSCEAR) for the period january 1995 to december 1998
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...
Dose calculation from a D-D-reaction-based BSA for boron neutron capture synovectomy
International Nuclear Information System (INIS)
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.
Dose calculation from a D-D-reaction-based BSA for boron neutron capture synovectomy
Energy Technology Data Exchange (ETDEWEB)
Abdalla, Khalid [Department of Physics, Hail University, Hail (Saudi Arabia)], E-mail: khalidafnan@uoh.edu.sa; Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals and Center for Applied Physical Sciences, Box No. 1815, Dhahran 31261 (Saudi Arabia)], E-mail: aanaqvi@kfupm.edu.sa; Maalej, N.; Elshahat, B. [Department of Physics, King Fahd University of Petroleum and Minerals and Center for Applied Physical Sciences, Box No. 1815, Dhahran 31261 (Saudi Arabia)
2010-04-15
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.
Directory of Open Access Journals (Sweden)
Jingyu Zhang
2016-01-01
Full Text Available In water-cooled reactor, the dominant radioactive source term under normal operation is activated corrosion products (ACPs, which have an important impact on reactor inspection and maintenance. A three-node transport model of ACPs was introduced into the new version of ACPs source term code CATE in this paper, which makes CATE capable of theoretically simulating the variation and the distribution of ACPs in a water-cooled reactor and suitable for more operating conditions. For code testing, MIT PWR coolant chemistry loop was simulated, and the calculation results from CATE are close to the experimental results from MIT, which means CATE is available and credible on ACPs analysis of water-cooled reactor. Then ACPs in the blanket cooling loop of water-cooled fusion reactor ITER under construction were analyzed using CATE and the results showed that the major contributors are the short-life nuclides, especially Mn-56. At last a point kernel integration code ARShield was coupled with CATE, and the dose rate around ITER blanket cooling loop was calculated. Results showed that after shutting down the reactor only for 8 days, the dose rate decreased nearly one order of magnitude, which was caused by the rapid decay of the short-life ACPs.
Monte Carlo Calculations of Dose to Medium and Dose to Water for Carbon Ion Beams in Various Media
DEFF Research Database (Denmark)
Herrmann, Rochus; Petersen, Jørgen B.B.; Jäkel, Oliver;
treatment plans. Here, we quantisize the effect of dose to water vs. dose to medium for a series of typical target materials found in medical physics. 2 Material and Methods The Monte Carlo code FLUKA [Battistioni et al. 2007] is used to simulate the particle fluence spectrum in a series of target......1 Background In clinical practice the quantity dose to water (Dw ) is used as a reference standard for dosimeters and treatment planning systems. Treatment planning systems usually rely on analytical representation of the particle beam, which are normally expressed as dose with respect to water...... for water. This represents the case that our “detector” is an infinitesimal small non-perturbing entity made of water, where charged particle equilibrium can be assumed following the Bragg-Gray cavity theory. Dw and Dm are calculated for typical materials such as bone, brain, lung and soft-tissues using...
Monte Carlo calculation of 60Co γ-ray's albedo-dose rate from the air
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The Monte Carlo calculation of 60Co γ-ray's albedo-dose rate from the air is reported. A formula is presented with which the relations of the albedo-doserate with some parameters are simulated and fitted
Energy Technology Data Exchange (ETDEWEB)
Westerly, David C. [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States); Mo Xiaohu; DeLuca, Paul M. Jr. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 (United States); Tome, Wolfgang A. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 and Institute of Onco-Physics, Albert Einstein College of Medicine and Division of Medical Physics, Department of Radiation Oncology, Montefiore Medical Center, Bronx, New York 10461 (United States); Mackie, Thomas R. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 and Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53792 (United States)
2013-06-15
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)] 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 Moliere 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 much as 1.4 mm (21%) at
International Nuclear Information System (INIS)
The authors report calculations performed using the MNCP and PENELOPE codes to determine the Hp(3)/K air conversion coefficient which allows the Hp(3) dose equivalent to be determined from the measured value of the kerma in the air. They report the definition of the phantom, a 20 cm diameter and 20 cm high cylinder which is considered as representative of a head. Calculations are performed for an energy range corresponding to interventional radiology or cardiology (20 keV-110 keV). Results obtained with both codes are compared
International Nuclear Information System (INIS)
is associated with the lower PTV coverage in AXB-recalculated plans. No obvious trend was observed between the calculation-resulted TCP differences and tumor size or location. AAA and AXB yield very similar NTCP on lung pneumonitis according to the LKB model estimation in the present study. AAA apparently overestimates the PTV dose; the magnitude of resulting difference in calculated TCP was up to 5.8 % in our study. AAA and AXB yield very similar NTCP on lung pneumonitis based on the LKB model parameter sets we used in the present study
Liang, X.; Penagaricano, J.; Zheng, D.; Morrill, S.; Zhang, X; Corry, P.; Griffin, R. J.; Han, E. Y.; Hardee, M.; Ratanatharathom, V.
2016-01-01
Background The aim of this study is to evaluate the radiobiological impact of Acuros XB (AXB) vs. Anisotropic Analytic Algorithm (AAA) dose calculation algorithms in combined dose-volume and biological optimized IMRT plans of SBRT treatments for non-small-cell lung cancer (NSCLC) patients. Methods Twenty eight patients with NSCLC previously treated SBRT were re-planned using Varian Eclipse (V11) with combined dose-volume and biological optimization IMRT sliding window technique. The total dos...
Zamani, M.; Kasesaz, Y.; Khalafi, H.; Pooya, S. M. Hosseini
Boron Neutron Capture Therapy (BNCT) is used for treatment of many diseases, including brain tumors, in many medical centers. In this method, a target area (e.g., head of patient) is irradiated by some optimized and suitable neutron fields such as research nuclear reactors. Aiming at protection of healthy tissues which are located in the vicinity of irradiated tissue, and based on the ALARA principle, it is required to prevent unnecessary exposure of these vital organs. In this study, by using numerical simulation method (MCNP4C Code), the absorbed dose in target tissue and the equiavalent dose in different sensitive tissues of a patiant treated by BNCT, are calculated. For this purpose, we have used the parameters of MIRD Standard Phantom. Equiavelent dose in 11 sensitive organs, located in the vicinity of target, and total equivalent dose in whole body, have been calculated. The results show that the absorbed dose in tumor and normal tissue of brain equal to 30.35 Gy and 0.19 Gy, respectively. Also, total equivalent dose in 11 sensitive organs, other than tumor and normal tissue of brain, is equal to 14 mGy. The maximum equivalent doses in organs, other than brain and tumor, appear to the tissues of lungs and thyroid and are equal to 7.35 mSv and 3.00 mSv, respectively.
THE RESULTS OF INDIVIDUAL DOSE CONTROL OF HEALTH INSTITUTIONS STAFF
Directory of Open Access Journals (Sweden)
E. N. Shleenkova
2014-01-01
Full Text Available The work provides comparative assessment of the levels of occupational exposure of Saint-Petersburg health institutions staff. The analysis was carried out of the 891 individual doses measurement results which have being obtained during 5 years investigations (2009-2013. The comparing of the average annual effective doses was carried out for 4 groups of medical specialists: x-ray laboratory assistant, radiotherapist, radiographer of dental clinics and X-ray surgery staff (surgeons, anesthesiologists and surgical nurses who are working close to irradiation source. It is shown that the annual effective dose average value is about 0.5 mSv for the first three groups of medical specialists. The same value for X-ray surgery staff is 1.6 mSv. Individual annual exposure doses have not exceeded the main dose limits required by Radiation Safety Standard 99/2009. The issues are considered of the estimation exactness of the effective dose basing on the results of individual dose equivalent measurement.
Large space shell model calculations with small space results
Zamick, Larry; Yu, Xiafei
2015-01-01
We note that in large space shell model calculaiotns and experiment one sometimes get results, the form of which also appear in smaller space calculations. On the other hand there are some results which demand the large space approach.
Geng, Changran; Tang, Xiaobin; Guan, Fada; Johns, Jesse; Vasudevan, Latha; Gong, Chunhui; Shu, Diyun; Chen, Da
2016-03-01
The purpose of this study is to verify the feasibility of applying GEANT4 (version 10.01) in neutron dose calculations in radiation protection by comparing the calculation results with MCNP5. The depth dose distributions are investigated in a homogeneous phantom, and the fluence-to-dose conversion coefficients are calculated for different organs in the Chinese hybrid male phantom for neutrons with energy ranging from 1 × 10(-9) to 10 MeV. By comparing the simulation results between GEANT4 and MCNP5, it is shown that using the high-precision (HP) neutron physics list, GEANT4 produces the closest simulation results to MCNP5. However, differences could be observed when the neutron energy is lower than 1 × 10(-6) MeV. Activating the thermal scattering with an S matrix correction in GEANT4 with HP and MCNP5 in thermal energy range can reduce the difference between these two codes. PMID:26156875
International Nuclear Information System (INIS)
The purpose of this study is to verify the feasibility of applying GEANT4 (version 10.01) in neutron dose calculations in radiation protection by comparing the calculation results with MCNP5. The depth dose distributions are investigated in a homogeneous phantom, and the fluence-to-dose conversion coefficients are calculated for different organs in the Chinese hybrid male phantom for neutrons with energy ranging from 1 x 10-9 to 10 MeV. By comparing the simulation results between GEANT4 and MCNP5, it is shown that using the high-precision (HP) neutron physics list, GEANT4 produces the closest simulation results to MCNP5. However, differences could be observed when the neutron energy is lower than 1 x 10-6 MeV. Activating the thermal scattering with an S matrix correction in GEANT4 with HP and MCNP5 in thermal energy range can reduce the difference between these two codes. (authors)
Lung Dose Calculation With SPECT/CT for {sup 90}Yittrium Radioembolization of Liver Cancer
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Yu, Naichang, E-mail: yun@ccf.org [Department of Radiation Oncology, Cleveland Clinic, Cleveland, OH (United States); Srinivas, Shaym M.; DiFilippo, Frank P.; Shrikanthan, Sankaran [Department of Nuclear Medicine, Cleveland Clinic, Cleveland, OH (United States); Levitin, Abraham; McLennan, Gordon; Spain, James [Department of Interventional Radiology, Cleveland Clinic, Cleveland, OH (United States); Xia, Ping; Wilkinson, Allan [Department of Radiation Oncology, Cleveland Clinic, Cleveland, OH (United States)
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.
CALCULATION STUDIES OF SPATIAL DISTRIBUTION OF THE ABSORBED DOSE RATE FOR VARIOUS SEEDS
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N. A. Nerozin
2015-01-01
Full Text Available Purpose. Conducting computational studies of dosimetric characteristics of microsources with the radionuclide I‑125, pilot production of which is established in the research and production complex of isotope and radiopharmaceuticals, JSC “State Scientific Centre of the Russian Federation — Institute for Physics and Power Engineering named after A. I. Leypunsky” (SSC RF IPPE. Sources of production IPPE are similar to the model 6711 of the company Nicomed Amersham, dosimetric characteristics of which are standardized in accordance with the TG43 AAPM formalism.Materials and methods. Microsourse «SEED No. 6711» (model of the company Nicomed Amersham is hermetically sealed in a titanium capsule silver rod covered with a thin layer of radioactive I‑125. The half-life of iodine‑125 is 59,43 days. In the process of decay of I‑125 is converted into the Te‑125.Calculation of parameters of microsources and their comparison with the standard model 6711 is carried out with use of the computer code MCNP.Results. The method of calculation of the basic dosimetric characteristics of the microsourse SSC RF-IPPE in accordance with the TG43 formalism is developed. A comparative analysis of experimental data and calculated results by MCNP code, which allowed to identify possible reasons for differences, is performed. The estimated dose characteristics and recommended standard data for dose characteristics of micro «SEED No. 6711» are compared.Conclusions. There are two possible reasons for the differences between experimental and calculated results. The first one may be the roughness of the surface of a silver rod or diffusion of radioactive iodine in silver. The second reason might be the difference of the cross sections of the characteristic radiation of silver used in MCNP code. In the comparison of calculated dose characteristics and recommended standard the role of the application activity is very important. In compliance with the standard
A clinical study of lung cancer dose calculation accuracy with Monte Carlo simulation
Zhao, Yanqun; Qi, Guohai; Yin, Gang; Wang, Xianliang; Wang, Pei; Li, Jian; Xiao, Mingyong; Li, Jie; Kang, Shengwei; Liao, Xiongfei
2014-01-01
Background The accuracy of dose calculation is crucial to the quality of treatment planning and, consequently, to the dose delivered to patients undergoing radiation therapy. Current general calculation algorithms such as Pencil Beam Convolution (PBC) and Collapsed Cone Convolution (CCC) have shortcomings in regard to severe inhomogeneities, particularly in those regions where charged particle equilibrium does not hold. The aim of this study was to evaluate the accuracy of the PBC and CCC alg...
X-ray tube output based calculation of patient entrance surface dose: validation of the method
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Harju, O.; Toivonen, M.; Tapiovaara, M.; Parviainen, T. [Radiation and Nuclear Safety Authority, Helsinki (Finland)
2003-06-01
X-ray departments need methods to monitor the doses delivered to the patients in order to be able to compare their dose level to established reference levels. For this purpose, patient dose per radiograph is described in terms of the entrance surface dose (ESD) or dose-area product (DAP). The actual measurement is often made by using a DAP-meter or thermoluminescent dosimeters (TLD). The third possibility, the calculation of ESD from the examination technique factors, is likely to be a common method for x-ray departments that do not have the other methods at their disposal or for examinations where the dose may be too low to be measured by the other means (e.g. chest radiography). We have developed a program for the determination of ESD by the calculation method and analysed the accuracy that can be achieved by this indirect method. The program calculates the ESD from the current time product, x-ray tube voltage, beam filtration and focus- to-skin distance (FSD). Additionally, for calibrating the dose calculation method and thereby improving the accuracy of the calculation, the x-ray tube output should be measured for at least one x-ray tube voltage value in each x-ray unit. The aim of the present work is to point out the restrictions of the method and details of its practical application. The first experiences from the use of the method will be summarised. (orig.)
International Nuclear Information System (INIS)
The nuclear medicine area has an increasing slope in the therapy of diseases, particularly in the treatment of radiosensitive tumors. Due to the high dose levels in radionuclide therapy, it is very important the accurate quantify of the dose distribution to avoid deleterious effects on healthy tissues. In Brazil, the internal dosimetry system used is the MIRD (Medical Internal Radiation Dose) based on a reference model that does not have adequate patient data to obtain a dose accurate assessment in therapy. However, in recent years, internal radionuclide dosimetry evaluates the spatial dose distribution base ad on information obtained from CT and SPECT or PET images together with the using of Monte Carlo codes. Those systems are called patient-specific dosimetry systems. In the Nuclear Engineering Center at IPEN, this methodology is in development. When the CT images are inserted into the Monte Carlo code MCNP5 through of use of a interface software called SCMS the dosimetry can be accomplished using patient-specific data, resulting in a more accurate energy deposition in organs of interest. This work aim to contribute with the development of part of that patient-specific dosimetry for therapy. To achieve this goal we have proposed three specific objectives: (1) Development of a software to convert images from Computed Tomography (CT) in the tissue parameters (ρ, ω(ι)); (2) Development of a software to perform attenuation correction in nuclear medicine tomographic images (SPECT or PET) and to provide the map of relative activity and (3) Provide data to the SCMS code by these two software. The software developed for the rst specific objective was the Image Converter Computed Tomography (ICCT), which obtained a good accuracy to determine the density and the tissue composition; the elements that had high variation were carbon and oxygen. Fortunately, this variation for the energy range used in radionuclide therapy is not detrimental to the dose distribution. A
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Cunliffe, Alexandra R.; Armato, Samuel G.; White, Bradley; Justusson, Julia [Department of Radiology, The University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637 (United States); Contee, Clay; Malik, Renuka; Al-Hallaq, Hania A., E-mail: hal-hallaq@radonc.uchicago.edu [Department of Radiation and Cellular Oncology, The University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637 (United States)
2015-01-15
Purpose: To characterize the effects of deformable image registration of serial computed tomography (CT) scans on the radiation dose calculated from a treatment planning scan. Methods: Eighteen patients who received curative doses (≥60 Gy, 2 Gy/fraction) of photon radiation therapy for lung cancer treatment were retrospectively identified. For each patient, a diagnostic-quality pretherapy (4–75 days) CT scan and a treatment planning scan with an associated dose map were collected. To establish correspondence between scan pairs, a researcher manually identified anatomically corresponding landmark point pairs between the two scans. Pretherapy scans then were coregistered with planning scans (and associated dose maps) using the demons deformable registration algorithm and two variants of the Fraunhofer MEVIS algorithm (“Fast” and “EMPIRE10”). Landmark points in each pretherapy scan were automatically mapped to the planning scan using the displacement vector field output from each of the three algorithms. The Euclidean distance between manually and automatically mapped landmark points (d{sub E}) and the absolute difference in planned dose (|ΔD|) were calculated. Using regression modeling, |ΔD| was modeled as a function of d{sub E}, dose (D), dose standard deviation (SD{sub dose}) in an eight-pixel neighborhood, and the registration algorithm used. Results: Over 1400 landmark point pairs were identified, with 58–93 (median: 84) points identified per patient. Average |ΔD| across patients was 3.5 Gy (range: 0.9–10.6 Gy). Registration accuracy was highest using the Fraunhofer MEVIS EMPIRE10 algorithm, with an average d{sub E} across patients of 5.2 mm (compared with >7 mm for the other two algorithms). Consequently, average |ΔD| was also lowest using the Fraunhofer MEVIS EMPIRE10 algorithm. |ΔD| increased significantly as a function of d{sub E} (0.42 Gy/mm), D (0.05 Gy/Gy), SD{sub dose} (1.4 Gy/Gy), and the algorithm used (≤1 Gy). Conclusions: An
The Criticality Calculation Of Fission Yield Of U-235 Solution And Its Radiation Dose
International Nuclear Information System (INIS)
The calculation assesment of fission yield of U-235 solution in the extraction and evaporation units has been performed for the prediction of that when the criticality accident occurs in the production of fuel element for the research reactor. The Grover Tuck and fission distribution probability methods are used in this case. The calculation result using the fission distribution probability methods show the fission of 2,7 x 1018 for the uranium concentration of 200 grams/litre and that of 2,5 x 1018 fissions for U of 40 grams/litre in the extraction unit. The calculation results from the evaporation unit revealed the fission of 3,1 x 1018 for 400 grams/litre uranium and 1,77 x 1018 fissions for 80 grams/litre uranium. Using the Grover Tuck calculation method give results that 8,267 x 1017 fissions and 2,878 x 1017 fissions respectively. Radiation dose of 200 gram/litre solution is about 1450,29 Rad for neutron and 4785,96 Rad for gamma ray
Effect of elemental compositions on Monte Carlo dose calculations in proton therapy of eye tumors
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
Development of the Calculation Module for Uncertainty of Internal Dose Coefficients
International Nuclear Information System (INIS)
The ICRP (International Commission on Radiological Protection) provides the coefficients as point values without uncertainties, it is important to understand sources of uncertainty in the derivation of the coefficients. When internal dose coefficients are calculated, numerous factors are involved such as transfer rate in biokinetic models, absorption rates and deposition in respiratory tract model, fractional absorption in alimentary tract model, absorbed fractions (AF), nuclide information and organ mass. These factors have uncertainty respectively, which increases the uncertainty of internal dose coefficients by uncertainty propagation. Since the procedure of internal dose coefficients calculation is somewhat complicated, it is difficult to propagate the each uncertainty analytically. The development of module and calculation were performed by MATLAB. In this study, we developed the calculation module for uncertainty of the internal dose coefficient. In this module, uncertainty of various factor used to calculate the internal dose coefficient can be considered using the Monte Carlo sampling method. After developing the module, we calculated the internal dose coefficient for inhalation of 90Sr with the uncertainty and obtained the distribution and percentile values. It is expected that this study will contribute greatly to the uncertainty research on internal dosimetry. In the future, we will update the module to consider more uncertainties
A BrachyPhantom for verification of dose calculation of HDR brachytherapy planning system
Energy Technology Data Exchange (ETDEWEB)
Austerlitz, C. [Clinica Diana Campos, Recife, PE 52020-030 (Brazil); Campos, C. A. T. [Pontifícia Universidade Católica do Rio de Janeiro, RJ 22451-900 (Brazil)
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
MCNP Dose Calculations in a CT Phantom for Therapeutic External Photon Beam
Institute of Scientific and Technical Information of China (English)
Lamyae El Gonnouni; Tarek El Bardouni; Mariam Zoubair; Mohamed Idaornar; Abderrahmane Senhoo
2011-01-01
In this paper, we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code. This is a general-purpose Monte Carlo tool designed to transport neutron, photon and electron in three dimensional geometries. To examine the performance of MCNP5 code in the field of external radiotherapy, we performed the modeling of an Electron Density phantom (EDP) irradiated by photons from 60Co source. The model was used to calculate the Percent Depth Dose (PDD) at different depths in an EDP. One field size for PDD has been examined. A 60Co photons source placed at 80 cm source to surface distance (SSD). The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat.
Application of GEANT4 radiation transport toolkit to dose calculations in anthropomorphic phantoms
Rodrigues, P; Peralta, L; Alves, C; Chaves, A; Lopes, M C
2003-01-01
In this paper we present the 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 ...
A model of the circulating blood for use in radiation dose calculations
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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.
A model of the circulating blood for use in radiation dose calculations
Energy Technology Data Exchange (ETDEWEB)
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.
Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark
International Nuclear Information System (INIS)
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
Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.
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
Analysis of the dose calculation accuracy for IMRT in lung: A 2D approach
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Dvorak, Pavel; Stock, Markus; Kroupa, Bernhard; Bogner, Joachim; Georg, Diet mar [Div. of Medical Radiation Physics, Dept. of Radiotherapy and Radiobiology, AKH Vienna, Medical Univ. Vienna, Vienna (Austria)
2007-10-15
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 b.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 was observed when IMRT plans were recalculated with the CC algorithm, especially for the highest nominal energy. All b.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 inhomogeneity correction is
Analysis of the dose calculation accuracy for IMRT in lung: a 2D approach.
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 (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 inhomogeneity correction is
Analysis of the dose calculation accuracy for IMRT in lung: A 2D approach
International Nuclear Information System (INIS)
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 b.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 was observed when IMRT plans were recalculated with the CC algorithm, especially for the highest nominal energy. All b.gamma evaluations confirmed substantial improvement with the CC algorithm in 2D. While PB dose distributions showed most discrepancies in lower (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 inhomogeneity correction is used, lower energy photon
International Nuclear Information System (INIS)
With the rapidly growing number of CT examinations, the consequential radiation risk has aroused more and more attention. The average dose in each organ during CT scans can only be obtained by using Monte Carlo simulation with computational phantoms. Since children tend to have higher radiation sensitivity than adults, the radiation dose of pediatric CT examinations requires special attention and needs to be assessed accurately. So far, studies on organ doses from CT exposures for pediatric patients are still limited. In this work, a 1-year-old computational phantom was constructed. The body contour was obtained from the CT images of a 1-year-old physical phantom and the internal organs were deformed from an existing Chinese reference adult phantom. To ensure the organ locations in the 1-year-old computational phantom were consistent with those of the physical phantom, the organ locations in 1-year-old computational phantom were manually adjusted one by one, and the organ masses were adjusted to the corresponding Chinese reference values. Moreover, a CT scanner model was developed using the Monte Carlo technique and the 1-year-old computational phantom was applied to estimate organ doses derived from simulated CT exposures. As a result, a database including doses to 36 organs and tissues from 47 single axial scans was built. It has been verified by calculation that doses of axial scans are close to those of helical scans; therefore, this database could be applied to helical scans as well. Organ doses were calculated using the database and compared with those obtained from the measurements made in the physical phantom for helical scans. The differences between simulation and measurement were less than 25% for all organs. The result shows that the 1-year-old phantom developed in this work can be used to calculate organ doses in CT exposures, and the dose database provides a method for the estimation of 1-year-old patient doses in a variety of CT examinations. (paper)
Pan, Yuxi; Qiu, Rui; Gao, Linfeng; Ge, Chaoyong; Zheng, Junzheng; Xie, Wenzhang; Li, Junli
2014-09-21
With the rapidly growing number of CT examinations, the consequential radiation risk has aroused more and more attention. The average dose in each organ during CT scans can only be obtained by using Monte Carlo simulation with computational phantoms. Since children tend to have higher radiation sensitivity than adults, the radiation dose of pediatric CT examinations requires special attention and needs to be assessed accurately. So far, studies on organ doses from CT exposures for pediatric patients are still limited. In this work, a 1-year-old computational phantom was constructed. The body contour was obtained from the CT images of a 1-year-old physical phantom and the internal organs were deformed from an existing Chinese reference adult phantom. To ensure the organ locations in the 1-year-old computational phantom were consistent with those of the physical phantom, the organ locations in 1-year-old computational phantom were manually adjusted one by one, and the organ masses were adjusted to the corresponding Chinese reference values. Moreover, a CT scanner model was developed using the Monte Carlo technique and the 1-year-old computational phantom was applied to estimate organ doses derived from simulated CT exposures. As a result, a database including doses to 36 organs and tissues from 47 single axial scans was built. It has been verified by calculation that doses of axial scans are close to those of helical scans; therefore, this database could be applied to helical scans as well. Organ doses were calculated using the database and compared with those obtained from the measurements made in the physical phantom for helical scans. The differences between simulation and measurement were less than 25% for all organs. The result shows that the 1-year-old phantom developed in this work can be used to calculate organ doses in CT exposures, and the dose database provides a method for the estimation of 1-year-old patient doses in a variety of CT examinations.
Critical groups vs. representative person: dose calculations due to predicted releases from USEXA
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Ferreira, N.L.D., E-mail: nelson.luiz@ctmsp.mar.mil.br [Centro Tecnologico da Marinha (CTM/SP), Sao Paulo, SP (Brazil); Rochedo, E.R.R., E-mail: elainerochedo@gmail.com [Instituto de Radiprotecao e Dosimetria (lRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Mazzilli, B.P., E-mail: mazzilli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2013-07-01
The critical group cf Centro Experimental Aramar (CEA) site was previously defined based 00 the effluents releases to the environment resulting from the facilities already operational at CEA. In this work, effective doses are calculated to members of the critical group considering the predicted potential uranium releases from the Uranium Hexafluoride Production Plant (USEXA). Basically, this work studies the behavior of the resulting doses related to the type of habit data used in the analysis and two distinct situations are considered: (a) the utilization of average values obtained from official institutions (IBGE, IEA-SP, CNEN, IAEA) and from the literature; and (b) the utilization of the 95{sup tb} percentile of the values derived from distributions fit to the obtained habit data. The first option corresponds to the way that data was used for the definition of the critical group of CEA done in former assessments, while the second one corresponds to the use of data in deterministic assessments, as recommended by ICRP to estimate doses to the so--called 'representative person' . (author)
Radiotherapy dose calculation on KV cone-beam CT image for lung tumor using the CIRS calibration.
Ma, Changsheng; Cao, Jianping; Yin, Yong; Zhu, Jian
2014-01-01
On-board kilovoltage (KV) cone-beam computed tomography (CBCT) images are used predominantly for the setup of patients' positioning. The image data can also potentially be used for dose calculation with the precise calibration of Hounsfield units (HU) to electron density (HU-density). CBCT calibration was analyzed in this study. A clinical treatment planning system was employed for CT and KV CBCT image to dose calculations and subsequent comparisons. Two HU-density tables were generated using the Computerized Imaging Reference Systems (CIRS) phantom. The results showed that a maximum ∼4% dose discrepancy was observed for inserts. The single field isodose curves were very close. The lung clinical patient study indicated that the volume of lung tumor that achieved the prescribed dose in CBCT was lower than in the CT plan. Our study showed that the dosimetric accuracy of CBCT-based dose calculation for lung tumor is acceptable only for the purpose of dosimetric checks with calibration applied. KV CBCT images cannot replace traditional CT images for dose calculation accuracy. PMID:26766975
International Nuclear Information System (INIS)
This work aims to calculate the fluence to effective dose conversion coefficients, (E/Φ), for monoenergetic neutrons from 10-9 to 20 MeV, based on the radiation (wR) and tissue (wT) weighting factors values recommended by ICRP publications numbers 60 and 103. The organs and tissues absorbed doses were calculated using the radiation transport code MCNPX and a female anthropomorphic voxel-based simulator, assuming whole-body irradiation by plane-parallel beams, on the geometries of the antero-posterior (AP) and postero-anterior (PA) irradiation. Dose calculations were performed for 21 selected organs of the body, for which the International Commission on Radiological Protection and the International Commission on Radiological Units and Measurements have set tissue weighting factors for the determination of the effective dose. From comparison between the dose results calculated and the data reported for the MIRD model, it can be concluded that, the fluence to effective dose conversion coefficients obtained using the voxel simulator are underestimated by a factor of up to 5 times when compared with the one obtained by ICRP 74, using mathematical simulators. (author)
A clinical study of lung cancer dose calculation accuracy with Monte Carlo simulation
International Nuclear Information System (INIS)
The accuracy of dose calculation is crucial to the quality of treatment planning and, consequently, to the dose delivered to patients undergoing radiation therapy. Current general calculation algorithms such as Pencil Beam Convolution (PBC) and Collapsed Cone Convolution (CCC) have shortcomings in regard to severe inhomogeneities, particularly in those regions where charged particle equilibrium does not hold. The aim of this study was to evaluate the accuracy of the PBC and CCC algorithms in lung cancer radiotherapy using Monte Carlo (MC) technology. Four treatment plans were designed using Oncentra Masterplan TPS for each patient. Two intensity-modulated radiation therapy (IMRT) plans were developed using the PBC and CCC algorithms, and two three-dimensional conformal therapy (3DCRT) plans were developed using the PBC and CCC algorithms. The DICOM-RT files of the treatment plans were exported to the Monte Carlo system to recalculate. The dose distributions of GTV, PTV and ipsilateral lung calculated by the TPS and MC were compared. For 3DCRT and IMRT plans, the mean dose differences for GTV between the CCC and MC increased with decreasing of the GTV volume. For IMRT, the mean dose differences were found to be higher than that of 3DCRT. The CCC algorithm overestimated the GTV mean dose by approximately 3% for IMRT. For 3DCRT plans, when the volume of the GTV was greater than 100 cm3, the mean doses calculated by CCC and MC almost have no difference. PBC shows large deviations from the MC algorithm. For the dose to the ipsilateral lung, the CCC algorithm overestimated the dose to the entire lung, and the PBC algorithm overestimated V20 but underestimated V5; the difference in V10 was not statistically significant. PBC substantially overestimates the dose to the tumour, but the CCC is similar to the MC simulation. It is recommended that the treatment plans for lung cancer be developed using an advanced dose calculation algorithm other than PBC. MC can accurately
Fast Monte Carlo Simulation for Patient-specific CT/CBCT Imaging Dose Calculation
Jia, Xun; Gu, Xuejun; Jiang, Steve B
2011-01-01
Recently, X-ray imaging dose from computed tomography (CT) or cone beam CT (CBCT) scans has become a serious concern. Patient-specific imaging dose calculation has been proposed for the purpose of dose management. While Monte Carlo (MC) dose calculation can be quite accurate for this purpose, it suffers from low computational efficiency. In response to this problem, we have successfully developed a MC dose calculation package, gCTD, on GPU architecture under the NVIDIA CUDA platform for fast and accurate estimation of the x-ray imaging dose received by a patient during a CT or CBCT scan. Techniques have been developed particularly for the GPU architecture to achieve high computational efficiency. Dose calculations using CBCT scanning geometry in a homogeneous water phantom and a heterogeneous Zubal head phantom have shown good agreement between gCTD and EGSnrc, indicating the accuracy of our code. In terms of improved efficiency, it is found that gCTD attains a speed-up of ~400 times in the homogeneous water ...
Effects of the difference in tube voltage of the CT scanner on dose calculation
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.
Calculation of 8-methoxypsoralen dose according to body surface area in PUVA treatment
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Sakuntabhai, A.; Farr, P.M. [Royal Victoria Infirmary, Newcastle upon Tyne (United Kingdom). Dept. of Dermatology; Diffey, B.L. [Dryburn Hospital, Durham (United Kingdom). Regional Medical Physics Department
1995-12-01
In 41 patients about to start PUVA, the dose of 8-methoxypsoralen (8-MOP) was calculated conventionally according to body weight (0.6 mg/kg), or according to body surface area (25 mg/m{sup 2}) predicted from height and weight measurements. The two different methods of dosing were used on consecutive treatment days and the plasma 8-MOP concentration was measured on each occasion 2 h after ingestion of the crystalline form of 8-MOP, given to the nearest 10 mg. Body weight calculated doses ranged from 30 to 60 mg with a significant difference in the plasma 8-MOP concentration between the dose groups, indicating a systematic variation according to the weight of the patient. When calculated according to body surface area, only two doses were used (40 or 50 mg), and there was no significant difference in plasma 8-MOP concentration between the groups. Calculation of the dose of 8-MOP using body surface area may be performed quickly and simply provided the height and weight of individual patients is known. We provide evidence that this method of dosing will improve the therapeutic effect of PUVA in psoriasis. (Author).
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.
International Nuclear Information System (INIS)
A companion report, DOE/ET-0064/1, presents a geographic, cultural, and demographic profile of the Tennessee Valley Region study area. This report describes the calculations of radionuclide release and transport and of the resultant dose to the regional population, assuming a projected installed capacity of 220,000 MW in the year 2000, of which 144,000 MW would be nuclear. All elements of the fuel cycle were assumed to be in operation. The radiological dose was calculated as a one-year dose based on ingestion of 35 different food types as well as for nine non-food pathways, and was reported as dose to the total body and for six specific organs for each of four age groups (infant, child, teen, and adult). Results indicate that the average individual would receive an incremental dose of 7 x 10-4 millirems in the year 2000 from the operation of nuclear facilities within and adjacent to the region, five orders of magnitude smaller than the dose from naturally occurring radiation in the area. The major contributor to dose was found to be tritium, and the most significant pathways were immersion in air, inhalation of air, transpiration of tritium (absorption through the skin), and exposure radionuclide-containing soil. 60 references
FOOD: an interactive code to calculate internal radiation doses from contaminated food products
International Nuclear Information System (INIS)
An interactive code, FOOD, has been written in BASIC for the UNIVAC 1108 to facilitate calculation of internal radiation doses to man from radionuclides in food products. In the dose model, vegetation may be contaminated by either air or irrigation water containing radionuclides. The model considers two mechanisms for radionuclide contamination of vegetation: direct deposition on leaves and uptake from soil through the root system. 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. At present, doses may be calculated for the skin, total body and five internal organs from 190 radionuclides. Dose summaries can be displayed at the local terminal. Further details on percent contribution to dose by nuclide and by food type are available from an auxiliary high-speed printer. This output also includes estimated radionuclide concentrations in soil, plants and animal products
Dose calculation accuracy of lung planning with a commercial IMRT treatment planning system.
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
Calculation of Ambient (H*(10)) and Personal (Hp(10)) Dose Equivalent from a 252Cf Neutron Source
Energy Technology Data Exchange (ETDEWEB)
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.
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.
Calculation of fluence and absorbed dose in head tissues due to different photon energies
International Nuclear Information System (INIS)
Calculations of fluence and absorbed dose in head tissues due to different photon energies were carried out using the MCNPX code, to simulate two models of a patient's head: one spherical and another more realistic ellipsoidal. Both head models had concentric shells to describe the scalp skin, the cranium and the brain. The tumor was located at the center of the head and it was a 1 cm-radius sphere. The MCNPX code was run for different energies. Results showed that the fluence decreases as the photons pass through the different head tissues. It can be observed that, although the fluence into the tumor is different for both head models, absorbed dose is the same. - Highlights: • A Monte Carlo algorithm to simulate the passage of photons through a homogeneous material was developed. • Two models of a patient's head, one spherical and another more realistic ellipsoidal model, were simulated using the Monte Carlo code. • The fluence into the tumor is different for both head models, but absorbed dose in the tumor is the same
Estimates of Columbia River radionuclide concentrations: Data for Phase 1 dose calculations
International Nuclear Information System (INIS)
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
Monte Carlo calculation of dose to water of a 106Ru COB-type ophthalmic plaque
International Nuclear Information System (INIS)
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 and 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
Energy Technology Data Exchange (ETDEWEB)
Ballester, Facundo, E-mail: Facundo.Ballester@uv.es [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Carlsson Tedgren, Åsa [Department of Medical and Health Sciences (IMH), Radiation Physics, Faculty of Health Sciences, Linköping University, Linköping SE-581 85, Sweden and Department of Medical Physics, Karolinska University Hospital, Stockholm SE-171 76 (Sweden); Granero, Domingo [Department of Radiation Physics, ERESA, Hospital General Universitario, Valencia E-46014 (Spain); Haworth, Annette [Department of Physical Sciences, Peter MacCallum Cancer Centre and Royal Melbourne Institute of Technology, Melbourne, Victoria 3000 (Australia); Mourtada, Firas [Department of Radiation Oncology, Helen F. Graham Cancer Center, Christiana Care Health System, Newark, Delaware 19713 (United States); Fonseca, Gabriel Paiva [Instituto de Pesquisas Energéticas e Nucleares – IPEN-CNEN/SP, São Paulo 05508-000, Brazil and Department of Radiation Oncology (MAASTRO), GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Zourari, Kyveli; Papagiannis, Panagiotis [Medical Physics Laboratory, Medical School, University of Athens, 75 MikrasAsias, Athens 115 27 (Greece); Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Siebert, Frank-André [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel 24105 (Germany); Sloboda, Ron S. [Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada); and others
2015-06-15
different investigators. MC results were then compared against dose calculated using TG-43 and MBDCA methods. Results: TG-43 and PSS datasets were generated for the generic source, the PSS data for use with the ACE algorithm. The dose-rate constant values obtained from seven MC simulations, performed independently using different codes, were in excellent agreement, yielding an average of 1.1109 ± 0.0004 cGy/(h U) (k = 1, Type A uncertainty). MC calculated dose-rate distributions for the two plans were also found to be in excellent agreement, with differences within type A uncertainties. Differences between commercial MBDCA and MC results were test, position, and calculation parameter dependent. On average, however, these differences were within 1% for ACUROS and 2% for ACE at clinically relevant distances. Conclusions: A hypothetical, generic HDR {sup 192}Ir source was designed and implemented in two commercially available TPSs employing different MBDCAs. Reference dose distributions for this source were benchmarked and used for the evaluation of MBDCA calculations employing a virtual, cubic water phantom in the form of a CT DICOM image series. The implementation of a generic source of identical design in all TPSs using MBDCAs is an important step toward supporting univocal commissioning procedures and direct comparisons between TPSs.
Implementation of Monte Carlo Dose calculation for CyberKnife treatment planning
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.
Implementation of Monte Carlo Dose calculation for CyberKnife treatment planning
International Nuclear Information System (INIS)
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 (registered) 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 and 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
Implementation of Monte Carlo Dose calculation for CyberKnife treatment planning
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Ma, C-M; Li, J S; Deng, J; Fan, J [Radiation Oncology Department, Fox Chase Cancer Center, Philadelphia, PA (United States)], E-mail: Charlie.ma@fccc.edu
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 (registered) 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 and 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.
Evaluation of an electron Monte Carlo dose calculation algorithm for treatment planning.
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
Impact of dose calculation accuracy during optimization on lung IMRT plan quality.
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
International Nuclear Information System (INIS)
Dose distributions throughout the eye, from three types of beta-ray ophthalmic applicators, were calculated using the EGS4, ACCEPT 3.0, and other Monte Carlo codes. The applicators were those for which doses were measured in a recent international intercomparison [Med. Phys. 28, 1373 (2001)], planar applicators of 106Ru-106Rh and 90Sr-90Y and a concave 106Ru-106Rh applicator. The main purpose was to compare the results of the various codes with average experimental values. For the planar applicators, calculated and measured doses on the source axis agreed within the experimental errors (106Ru-106Rh and 5 mm for 90Sr-90Y. At greater distances the measured values are larger than those calculated. For the concave 106Ru-106Rh applicator, there was poor agreement among available calculations and only those calculated by ACCEPT 3.0 agreed with measured values. In the past, attempts have been made to derive such dose distributions simply, by integrating the appropriate point-source dose function over the source. Here, we investigated the accuracy of this procedure for encapsulated sources, by comparing such results with values calculated by Monte Carlo. An attempt was made to allow for the effects of the silver source window but no corrections were made for scattering from the source backing. In these circumstances, at 6 mm depth, the difference in the results of the two calculations was 14%-18% for a planar 106Ru-106Rh applicator and up to 30% for the concave applicator. It becomes worse at greater depths. These errors are probably caused mainly by differences between the spectrum of beta particles transmitted by the silver window and those transmitted by a thickness of water having the same attenuation properties
Calculation of dose-rate conversion factors for external exposure to photons and electrons
International Nuclear Information System (INIS)
Methods are presented for the calculation of dose-rate conversion factors for external exposure to photon and electron radiation from radioactive decay. A dose-rate conversion factor is defined as the dose-equivalent rate per unit radionuclide concentration. Exposure modes considered are immersion in contaminated air, immersion in contaminated water, and irradiation from a contaminated ground surface. For each radiation type and exposure mode, dose-rate conversion factors are derived for tissue-equivalent material at the body surface of an exposed individual. In addition, photon dose-rate conversion factors are estimated for 22 body organs. The calculations are based on the assumption that the exposure medium is infinite in extent and that the radionuclide concentration is uniform. The dose-rate conversion factors for immersion in contaminated air and water then follow from the requirement that all of the energy emitted in the radioactive decay is absorbed in the infinite medium. Dose-rate conversion factors for ground-surface exposure are calculated at a reference location above a smooth, infinite plane using the point-kernel integration method and known specific absorbed fractions for photons and electrons in air
Effects of the difference in tube voltage of the CT scanner on dose calculation
Rhee, Dong Joo; Moon, Young Min; Kim, Jung Ki; Jeong, Dong Hyeok
2015-01-01
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, CT number, which is directly proportional to the linear attenuation coefficient, is required to be converted to electron density for radiation dose calculation for cancer treatment. However, if various tube voltages were applied to take the patient CT image without applying the specific CT number to electron density conversion curve, the accuracy of dose calculation would be unassured. In this study, changes in CT numbers for different materials due to change in tube voltage were demonstrated and the dose calculation errors in percentage depth dose (PDD) and a clinical case were analyzed. The maximum dose difference in PDD from TPS dose calculation and Monte Carlo simulation were 1.3 % and 1.1 % respectively when applying the same CT number to electron density conversion curve to the 80 kVp and 140 kVp images. In the clinical case, the different CT nu...
Element-specific and constant parameters used for dose calculations in SR-Site
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Norden, Sara (Svensk Kaernbraenslehantering AB (Sweden)); Avila, Rodolfo; De la Cruz, Idalmis; Stenberg, Kristofer; Grolander, Sara (Facilia AB (Sweden))
2010-12-15
The report presents Best Estimate (BE) values and Probability Distribution Functions (PDFs) of Concentration Ratios (CR) for different types of terrestrial and aquatic biota and distribution coefficients (K{sub d}) for organic and inorganic deposits, as well as for suspended matter in freshwater and marine ecosystems. The BE values have been used in deterministic simulations for derivation of Landscape Dose Factors (LDF) applied for dose assessments in SR-Site. The PDFs have been used in probabilistic simulations for uncertainty and sensitivity analysis of the LDFs. The derivation of LDFs for SR-Site is described in /Avila et al. 2010/. The CR and K{sub d} values have been derived using both site-specific data measured at Laxemar and Forsmark during the site investigation program and literature data. These two data sources have been combined using Bayesian updating methods, which are described in detail in an Appendix, along with the input data used in the statistical analyses and the results obtained. The report also describes a kinetic-allometric model that was applied for deriving values of CR for terrestrial herbivores in cases when site and literature data for an element were missing. In addition, the report presents values for a number of other parameters used in the SR-Site Radionuclide Model for the biosphere: radionuclide decay-ingrowth data, elemental diffusivities, fractions of element content released during decomposition processes, ingestion of food, water and soil by cattle, elements retention fraction on plant surfaces during irrigation. The report also presents parameter values used in calculation of doses to a reference man: dose coefficients for inhalation, ingestion and external exposure, inhalation rates, ingestion rates of food and water
Element-specific and constant parameters used for dose calculations in SR-Site
International Nuclear Information System (INIS)
The report presents Best Estimate (BE) values and Probability Distribution Functions (PDFs) of Concentration Ratios (CR) for different types of terrestrial and aquatic biota and distribution coefficients (Kd) for organic and inorganic deposits, as well as for suspended matter in freshwater and marine ecosystems. The BE values have been used in deterministic simulations for derivation of Landscape Dose Factors (LDF) applied for dose assessments in SR-Site. The PDFs have been used in probabilistic simulations for uncertainty and sensitivity analysis of the LDFs. The derivation of LDFs for SR-Site is described in /Avila et al. 2010/. The CR and Kd values have been derived using both site-specific data measured at Laxemar and Forsmark during the site investigation program and literature data. These two data sources have been combined using Bayesian updating methods, which are described in detail in an Appendix, along with the input data used in the statistical analyses and the results obtained. The report also describes a kinetic-allometric model that was applied for deriving values of CR for terrestrial herbivores in cases when site and literature data for an element were missing. In addition, the report presents values for a number of other parameters used in the SR-Site Radionuclide Model for the biosphere: radionuclide decay-ingrowth data, elemental diffusivities, fractions of element content released during decomposition processes, ingestion of food, water and soil by cattle, elements retention fraction on plant surfaces during irrigation. The report also presents parameter values used in calculation of doses to a reference man: dose coefficients for inhalation, ingestion and external exposure, inhalation rates, ingestion rates of food and water
Recent developments in biokinetic models and the calculation of internal dose coefficients
International Nuclear Information System (INIS)
In most cases the measurement of radioactivity in an environmental or biological sample will be followed by some estimation of dose and possibly risk, either to a population or an individual. This will normally involve the use of a dose coefficient (dose per unit intake value) taken from a compendium. In recent years the calculation of dose coefficients has seen many developments in both biokinetic modelling and computational capabilities. ICRP has recommended new models for the respiratory tract and for the systemic behavior of many of the more important elements. As well as this, a general age-dependent calculation method has been developed which involves an effectively continuous variation of both biokinetic and dosimetric parameters, facilitating more realistic estimation of doses to young people. These new developments were used in work for recent ICRP, IAEA and CEC compendia of dose coefficients for both members of the public (including children) and workers. This paper presents a general overview of the method of calculation of internal doses with particular reference to the actinides. Some of the implications for dose coefficients of the new models are discussed. For example it is shown that compared with data in ICRP Publications 30 and 54: the new respiratory tract model generally predicts lower deposition in systemic tissues per unit intake; the new biokinetic models for actinides allow for burial of material deposited on bone surfaces; age-dependent models generally feature faster turnover of material in young people. All of these factors can lead to substantially different estimates of dose and examples of the new dose coefficients are given to illustrate these differences. During the development of the new models for actinides, human bioassay data were used to validate the model. Thus, one would expect the new models to give reasonable predictions of bioassay quantities. Some examples of the bioassay applications, e.g., excretion data for the
An OpenCL-based Monte Carlo dose calculation engine (oclMC) for coupled photon-electron transport
Tian, Zhen; Folkerts, Michael; Qin, Nan; Jiang, Steve B; Jia, Xun
2015-01-01
Monte Carlo (MC) method has been recognized the most accurate dose calculation method for radiotherapy. However, its extremely long computation time impedes clinical applications. Recently, a lot of efforts have been made to realize fast MC dose calculation on GPUs. Nonetheless, most of the GPU-based MC dose engines were developed in NVidia CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a fast cross-platform MC dose engine oclMC using OpenCL environment for external beam photon and electron radiotherapy in MeV energy range. Coupled photon-electron MC simulation was implemented with analogue simulations for photon transports and a Class II condensed history scheme for electron transports. To test the accuracy and efficiency of our dose engine oclMC, we compared dose calculation results of oclMC and gDPM, our previously developed GPU-based MC code, for a 15 MeV electron ...
Directory of Open Access Journals (Sweden)
Takashi Kadowaki
Full Text Available BACKGROUND: Pragmatic methods for dose optimization are required for the successful basal management in daily clinical practice. To derive a useful formula for calculating recommended glargine doses, we analyzed data from the Add-on Lantus® to Oral Hypoglycemic Agents (ALOHA study, a 24-week observation of Japanese type 2 diabetes patients. METHODOLOGY/PRINCIPAL FINDINGS: The patients who initiated insulin glargine in basal-supported oral therapy (BOT regimen (n = 3506 were analyzed. The correlations between average changes in glargine dose and HbA1c were calculated, and its regression formula was estimated from grouped data categorized by baseline HbA1c levels. Starting doses of the background-subgroup achieving the HbA1c target with a last-observed dose above the average were compared to an assumed optimal starting dose of 0.15 U/kg/day. The difference in regression lines between background-subgroups was examined. A formula for determining the optimal starting and titration doses was thereby derived. The correlation coefficient between changes in dose and HbA1c was -0.9043. The estimated regression line formula was -0.964 × change in HbA1c+2.000. A starting dose of 0.15 U/kg/day was applicable to all background-subgroups except for patients with retinopathy (0.120 U/kg/day and/or with eGFR<60 mL/min/1.73 m(2 (0.114 U/kg/day. Additionally, women (0.135 U/kg/day and patients with sulfonylureas (0.132 U/kg/day received a slightly decreased starting dose. CONCLUSIONS/SIGNIFICANCE: We suggest a simplified and pragmatic dose calculation formula for type 2 diabetes patients starting glargine BOT optimal daily dose at 24 weeks = starting dose (0.15×weight + incremental dose (baseline HbA1c - target HbA1c+2. This formula should be further validated using other samples in a prospective follow-up, especially since several patient groups required lower starting doses.
Concept for calculating dose rates from activated groundwater at accelerator sites
Prolingheuer, N; Vanderborght, J; Schlögl, B; Nabbi, R; Moormann, R
Licensing of particle accelerators requires the proof that the groundwater outside of the site will not be significantly contaminated by activation products formed below accelerator and target. In order to reduce the effort for this proof, a site independent simplified but conservative method is under development. The conventional approach for calculation of activation of soil and groundwater is shortly described on example of a site close to Forschungszentrum Juelich, Germany. Additionally an updated overview of a data library for partition coefficients for relevant nuclides transported in the aquifer at the site is presented. The approximate model for transport of nuclides with ground water including exemplary results on nuclide concentrations outside of the site boundary and of resulting effective doses is described. Further applications and developments are finally outlined.
Influence of metallic dental implants and metal artefacts on dose calculation accuracy
International Nuclear Information System (INIS)
Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy. Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic trademark EBT2 films. For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029). For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques. (orig.)
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Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2014-07-01
Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)
Computer calculation of dose distributions in radiotherapy. Report of a panel
International Nuclear Information System (INIS)
As in most areas of scientific endeavour, the advent of electronic computers has made a significant impact on the investigation of the physical aspects of radiotherapy. Since the first paper on the subject was published in 1955 the literature has rapidly expanded to include the application of computer techniques to problems of external beam, and intracavitary and interstitial dosimetry. By removing the tedium of lengthy repetitive calculations, the availability of automatic computers has encouraged physicists and radiotherapists to take a fresh look at many fundamental physical problems of radiotherapy. The most important result of the automation of dosage calculations is not simply an increase in the quantity of data but an improvement in the quality of data available as a treatment guide for the therapist. In October 1965 the International Atomic Energy Agency convened a panel in Vienna on the 'Use of Computers for Calculation of Dose Distributions in Radiotherapy' to assess the current status of work, provide guidelines for future research, explore the possibility of international cooperation and make recommendations to the Agency. The panel meeting was attended by 15 participants from seven countries, one observer, and two representatives of the World Health Organization. Participants contributed 20 working papers which served as the bases of discussion. By the nature of the work, computer techniques have been developed by a few advanced centres with access to large computer installations. However, several computer methods are now becoming 'routine' and can be used by institutions without facilities for research. It is hoped that the report of the Panel will provide a comprehensive view of the automatic computation of radiotherapeutic dose distributions and serve as a means of communication between present and potential users of computers
Independent dose calculation of the Tps Iplan in radiotherapy conformed with MLC
International Nuclear Information System (INIS)
The systems utilization of independent dose calculation in three dimensional-Conformal Radiation Therapy (3D-Crt) treatments allows a direct verification of the treatments times. The utilization of these systems allows diminishing the probability of errors occurrence generated by the treatment planning system (Tps), allowing a detailed analysis of the dose to delivering and review of the normalization point (Np) or prescription. The independent dose calculation is realized across the knowledge of dosimetric parameters of the treatment machine and particular characteristics of every individual field. The aim of this work is develops a calculation system of punctual doses for isocentric fields conformed with multi-leaf collimation systems (MLC), where the dose calculation is in conformity with the suggested ones by ICRU Report No. 42, 1987. Calculation software was realized in C ++ under a free platform of programming (Code::Blocks). The system uses files in format Rtp, exported from the Tps to systems of record and verification (Lantis). This file contains detailed information of the dose, Um, position of the MLC sheets and collimators for every field of treatment. The size of equivalent field is obtained from the positions of every sheet; the effective depth of calculation can be introduced from the dosimetric report of the Tps or automatically from the DFS of the field. The 3D coordinates of the isocenter and the Np for the treatment plan must be introduced manually. From this information the system looks the dosimetric parameters and calculates the Um. The calculations were realized in two accelerators a NOVALIS Tx (Varian) with 120 sheets of high definition (hd-MLC) and a PRIMUS Optifocus (Siemens) with 82 sheets. 705 patients were analyzed for a total of 1082, in plans made for both equipment s, the average uncertainty with regard to the calculation of the Tps is-0.43% ± 2.42% in a range between [-7.90 %, 7.50 %]. The major uncertainty was in Np near of the
Development of Japanese voxel models and their application to organ dose calculation
International Nuclear Information System (INIS)
Three Japanese voxel (volume pixel) phantoms in supine and upright postures, which are consisted of about 1 mm3 size voxels, have been developed on the basis of computed tomography (CT) images of healthy Japanese adult male and female volunteers. Their body structures are reproduced more realistically in comparison with most existing voxel phantoms. Organ doses due to internal or external exposures were calculated using the developed phantoms. In estimation of radiation dose from radionuclides incorporated into body, specific absorbed fractions (SAFs) for low energy photon were significantly influenced by the changes in postures. In estimation of organ doses due to external exposures, the doses of some organs of the developed phantom were calculated and were compared with those of a previous Japanese voxel phantom (voxel size: 0.98x0.98x10 mm3) and the reference values of ICRP Publication 74. (author)
Effects of human model configuration in Monte Carlo calculations on organ doses from CT examinations
International Nuclear Information System (INIS)
A new dosimetry system, WAZA-ARI, is being developed to estimate radiation dose from Computed Tomography (CT) examination in Japan. The dose estimation in WAZA-ARI utilizes organ dose data, which have been derived by Monte Carlo calculations using Particle and Heavy Ion Transport code System, PHITS. A Japanese adult male phantom, JM phantom, is adapted as a reference human model in the calculations, because the physique and inner organ masses agree well with the average values for Japanese adult males. On the other hand, each patient has arbitrary physical characteristics. Thus, the effects of human body configuration on organ doses are studied by applying another Japanese male model and the reference phantom by the International Commission on Radiological Protection (ICRP) to PHITS. In addition, this paper describes computation conditions for the three human models, which are constructed in the format of voxel phantom with different resolutions. (author)
Energy Technology Data Exchange (ETDEWEB)
Adrada, A; Miller, E; Tello, Z; Medina, L; Garrigo, E; Venencia, C [Instituto de Radioterapia - Fundacion Marie Curie, Cordoba (Argentina)
2014-06-01
Purpose: The purpose of this work was to develop and validate an open source independent MU dose calculation software for S and S IMRT based in the algorithm proposed by Kung et.al. Methods: Treatment plans were done using Iplan v4.5 BrainLAB TPS and S and S IMRT modality. A 6MV photon beam produced by a Primus linear accelerator equipped with an Optifocus MLC was used. TPS dose calculation algorithms were pencil beam and Monte Carlo. 230 IMRT treatments plans were selected for the study. The software was written under MALTLAB environment. Treatment plans were imported by the software using RTP format. Field fluences were reconstructed adding all segments.The algorithm implemented in the software calculates the dose at a reference point as the sum of primary and scatter dose. The primary dose is obtained by masking the fluence map with a circle of radius 1cm. The scatter dose is obtained through a shaped ring mask around the previous circle with a thickness of 0.5cm; the rings are increased one after another with constant thickness until cover the entire map of influence. The dosimetric parameters Sc, Sp and TPR vary depending on radio, the transmission effect of the MLC, inverse square law and dose profile are used for the calculation. Results: The average difference between measured and independent calculated dose was 0.4% ± 2.2% [−6.8%, 6.4%]. For 91% of the studied plans the difference was less than 3%. The difference between the measured and TPS dose with pencilbeam algorithm was 2.6% ± 1.41% [−2.0%, 5.6%] and Monte Carlo algorithm was 0.4% ± 1.5% [−4.9%, 3.7%]. The differences obtained are comparable to that obtained with the ionization chamber and TPS. Conclusion: The developed software is suitable for use in S and S IMRT dose calculation. This application is open and can be downloading under request.
Impact of temporal probability in 4D dose calculation for lung tumors.
Rouabhi, Ouided; Ma, Mingyu; Bayouth, John; Xia, Junyi
2015-11-08
The purpose of this study was to evaluate the dosimetric uncertainty in 4D dose calculation using three temporal probability distributions: uniform distribution, sinusoidal distribution, and patient-specific distribution derived from the patient respiratory trace. Temporal probability, defined as the fraction of time a patient spends in each respiratory amplitude, was evaluated in nine lung cancer patients. Four-dimensional computed tomography (4D CT), along with deformable image registration, was used to compute 4D dose incorporating the patient's respiratory motion. First, the dose of each of 10 phase CTs was computed using the same planning parameters as those used in 3D treatment planning based on the breath-hold CT. Next, deformable image registration was used to deform the dose of each phase CT to the breath-hold CT using the deformation map between the phase CT and the breath-hold CT. Finally, the 4D dose was computed by summing the deformed phase doses using their corresponding temporal probabilities. In this study, 4D dose calculated from the patient-specific temporal probability distribution was used as the ground truth. The dosimetric evaluation matrix included: 1) 3D gamma analysis, 2) mean tumor dose (MTD), 3) mean lung dose (MLD), and 4) lung V20. For seven out of nine patients, both uniform and sinusoidal temporal probability dose distributions were found to have an average gamma passing rate > 95% for both the lung and PTV regions. Compared with 4D dose calculated using the patient respiratory trace, doses using uniform and sinusoidal distribution showed a percentage difference on average of -0.1% ± 0.6% and -0.2% ± 0.4% in MTD, -0.2% ± 1.9% and -0.2% ± 1.3% in MLD, 0.09% ± 2.8% and -0.07% ± 1.8% in lung V20, -0.1% ± 2.0% and 0.08% ± 1.34% in lung V10, 0.47% ± 1.8% and 0.19% ± 1.3% in lung V5, respectively. We concluded that four-dimensional dose computed using either a uniform or sinusoidal temporal probability distribution can
TU-F-18A-03: Improving Tissue Segmentation for Monte Carlo Dose Calculation Using DECT Data
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Di, Salvio A; Bedwani, S; Carrier, J [CHUM - Notre-Dame, Montreal, QC (Canada)
2014-06-15
Purpose: To develop a new segmentation technique using dual energy CT (DECT) to overcome limitations related to segmentation from a standard Hounsfield unit (HU) to electron density (ED) calibration curve. Both methods are compared with a Monte Carlo analysis of dose distribution. Methods: DECT allows a direct calculation of both ED and effective atomic number (EAN) within a given voxel. The EAN is here defined as a function of the total electron cross-section of a medium. These values can be effectively acquired using a calibrated method from scans at two different energies. A prior stoichiometric calibration on a Gammex RMI phantom allows us to find the parameters to calculate EAN and ED within a voxel. Scans from a Siemens SOMATOM Definition Flash dual source system provided the data for our study. A Monte Carlo analysis compares dose distribution simulated by dosxyz-nrc, considering a head phantom defined by both segmentation techniques. Results: Results from depth dose and dose profile calculations show that materials with different atomic compositions but similar EAN present differences of less than 1%. Therefore, it is possible to define a short list of basis materials from which density can be adapted to imitate interaction behavior of any tissue. Comparison of the dose distributions on both segmentations shows a difference of 50% in dose in areas surrounding bone at low energy. Conclusion: The presented segmentation technique allows a more accurate medium definition in each voxel, especially in areas of tissue transition. Since the behavior of human tissues is highly sensitive at low energies, this reduces the errors on calculated dose distribution. This method could be further developed to optimize the tissue characterization based on anatomic site.
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Azcona, J [Department of Radiation Physics, Clinica Universidad de Navarra (Spain); Burguete, J [Universidad de Navarra, Pamplona, Navarra (Spain)
2014-06-01
Purpose: To obtain the pencil beam kernels that characterize a megavoltage photon beam generated in a FFF linac by experimental measurements, and to apply them for dose calculation in modulated fields. Methods: Several Kodak EDR2 radiographic films were irradiated with a 10 MV FFF photon beam from a Varian True Beam (Varian Medical Systems, Palo Alto, CA) linac, at the depths of 5, 10, 15, and 20cm in polystyrene (RW3 water equivalent phantom, PTW Freiburg, Germany). The irradiation field was a 50 mm diameter circular field, collimated with a lead block. Measured dose leads to the kernel characterization, assuming that the energy fluence exiting the linac head and further collimated is originated on a point source. The three-dimensional kernel was obtained by deconvolution at each depth using the Hankel transform. A correction on the low dose part of the kernel was performed to reproduce accurately the experimental output factors. The kernels were used to calculate modulated dose distributions in six modulated fields and compared through the gamma index to their absolute dose measured by film in the RW3 phantom. Results: The resulting kernels properly characterize the global beam penumbra. The output factor-based correction was carried out adding the amount of signal necessary to reproduce the experimental output factor in steps of 2mm, starting at a radius of 4mm. There the kernel signal was in all cases below 10% of its maximum value. With this correction, the number of points that pass the gamma index criteria (3%, 3mm) in the modulated fields for all cases are at least 99.6% of the total number of points. Conclusion: A system for independent dose calculations in modulated fields from FFF beams has been developed. Pencil beam kernels were obtained and their ability to accurately calculate dose in homogeneous media was demonstrated.
SU-E-I-06: A Dose Calculation Algorithm for KV Diagnostic Imaging Beams by Empirical Modeling
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Chacko, M; Aldoohan, S; Sonnad, J; Ahmad, S; Ali, I [University of Oklahoma Health Science Center, Oklahoma City, OK (United States)
2015-06-15
Purpose: To develop accurate three-dimensional (3D) empirical dose calculation model for kV diagnostic beams for different radiographic and CT imaging techniques. Methods: Dose was modeled using photon attenuation measured using depth dose (DD), scatter radiation of the source and medium, and off-axis ratio (OAR) profiles. Measurements were performed using single-diode in water and a diode-array detector (MapCHECK2) with kV on-board imagers (OBI) integrated with Varian TrueBeam and Trilogy linacs. The dose parameters were measured for three energies: 80, 100, and 125 kVp with and without bowtie filters using field sizes 1×1–40×40 cm2 and depths 0–20 cm in water tank. Results: The measured DD decreased with depth in water because of photon attenuation, while it increased with field size due to increased scatter radiation from medium. DD curves varied with energy and filters where they increased with higher energies and beam hardening from half-fan and full-fan bowtie filters. Scatter radiation factors increased with field sizes and higher energies. The OAR was with 3% for beam profiles within the flat dose regions. The heal effect of this kV OBI system was within 6% from the central axis value at different depths. The presence of bowtie filters attenuated measured dose off-axis by as much as 80% at the edges of large beams. The model dose predictions were verified with measured doses using single point diode and ionization chamber or two-dimensional diode-array detectors inserted in solid water phantoms. Conclusion: This empirical model enables fast and accurate 3D dose calculation in water within 5% in regions with near charge-particle equilibrium conditions outside buildup region and penumbra. It considers accurately scatter radiation contribution in water which is superior to air-kerma or CTDI dose measurements used usually in dose calculation for diagnostic imaging beams. Considering heterogeneity corrections in this model will enable patient specific dose
Ulmer, W.; Schaffner, B.
2010-01-01
We have developed a model for proton depth dose and lateral distributions based on Monte Carlo calculations (GEANT4) and an integration procedure of the 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 inclusion of two different origins: 1. S...
Dose rate calculations for the removal of the mixer pump from Tank 101 SY
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Plans are currently being made for the removal of the mixer pump in tank 101 SY. Because the pump is contaminated with radioactive waste, it is essential that those involved in the pump removal operation have an indication of the expected dose rates when the pump is removed. Calculations were made to determine the dose rates for removing the pump, inserting the pump into a shipping container and filling the shipping container with either steel or lead shot for shielding
Vanderstraeten, Barbara; Reynaert, Nick; Paelinck, Leen; Madani, Indira; De Wagter, Carlos; De Gersem, Werner; De Neve, Wilfried; Thierens, Hubert
2006-09-01
The accuracy of dose computation within the lungs depends strongly on the performance of the calculation algorithm in regions of electronic disequilibrium that arise near tissue inhomogeneities with large density variations. There is a lack of data evaluating the performance of highly developed analytical dose calculation algorithms compared to Monte Carlo computations in a clinical setting. We compared full Monte Carlo calculations (performed by our Monte Carlo dose engine MCDE) with two different commercial convolution/superposition (CS) implementations (Pinnacle-CS and Helax-TMS's collapsed cone model Helax-CC) and one pencil beam algorithm (Helax-TMS's pencil beam model Helax-PB) for 10 intensity modulated radiation therapy (IMRT) lung cancer patients. Treatment plans were created for two photon beam qualities (6 and 18 MV). For each dose calculation algorithm, patient, and beam quality, the following set of clinically relevant dose-volume values was reported: (i) minimal, median, and maximal dose (Dmin, D50, and Dmax) for the gross tumor and planning target volumes (GTV and PTV); (ii) the volume of the lungs (excluding the GTV) receiving at least 20 and 30 Gy (V20 and V30) and the mean lung dose; (iii) the 33rd percentile dose (D33) and Dmax delivered to the heart and the expanded esophagus; and (iv) Dmax for the expanded spinal cord. Statistical analysis was performed by means of one-way analysis of variance for repeated measurements and Tukey pairwise comparison of means. Pinnacle-CS showed an excellent agreement with MCDE within the target structures, whereas the best correspondence for the organs at risk (OARs) was found between Helax-CC and MCDE. Results from Helax-PB were unsatisfying for both targets and OARs. Additionally, individual patient results were analyzed. Within the target structures, deviations above 5% were found in one patient for the comparison of MCDE and Helax-CC, while all differences between MCDE and Pinnacle-CS were below 5%. For both
International Nuclear Information System (INIS)
The accuracy of dose computation within the lungs depends strongly on the performance of the calculation algorithm in regions of electronic disequilibrium that arise near tissue inhomogeneities with large density variations. There is a lack of data evaluating the performance of highly developed analytical dose calculation algorithms compared to Monte Carlo computations in a clinical setting. We compared full Monte Carlo calculations (performed by our Monte Carlo dose engine MCDE) with two different commercial convolution/superposition (CS) implementations (Pinnacle-CS and Helax-TMS's collapsed cone model Helax-CC) and one pencil beam algorithm (Helax-TMS's pencil beam model Helax-PB) for 10 intensity modulated radiation therapy (IMRT) lung cancer patients. Treatment plans were created for two photon beam qualities (6 and 18 MV). For each dose calculation algorithm, patient, and beam quality, the following set of clinically relevant dose-volume values was reported: (i) minimal, median, and maximal dose (Dmin, D50, and Dmax) for the gross tumor and planning target volumes (GTV and PTV); (ii) the volume of the lungs (excluding the GTV) receiving at least 20 and 30 Gy (V20 and V30) and the mean lung dose; (iii) the 33rd percentile dose (D33) and Dmax delivered to the heart and the expanded esophagus; and (iv) Dmax for the expanded spinal cord. Statistical analysis was performed by means of one-way analysis of variance for repeated measurements and Tukey pairwise comparison of means. Pinnacle-CS showed an excellent agreement with MCDE within the target structures, whereas the best correspondence for the organs at risk (OARs) was found between Helax-CC and MCDE. Results from Helax-PB were unsatisfying for both targets and OARs. Additionally, individual patient results were analyzed. Within the target structures, deviations above 5% were found in one patient for the comparison of MCDE and Helax-CC, while all differences between MCDE and Pinnacle-CS were below 5%. For both
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A flexible and interactive code, NEPTUN, has been written in FORTRAN IV for the PDP-10 computer to assess the impact on man of radionuclides in aquatic food chains. NEPTUN is based on an equilibrium model of the linear-chain type, and calculates aquatic food concentrations and doses to man. A decay term is included for the holdup time of the various food types. A total of seven food types can be selected, which include drinking water, freshwater and salt-water plants, inverebrates and fish. Thirty different diets can be implemented and five different dose factor files can be chosen. These include dose conversion factors for infants and adults based on ICRP 2 and ICRP 26 methodologies. All dose factors involve a dose commitment of 50 years, or equivalently, 50 years of chronic exposure. To date, only stochastic ICRP 26 dose caluclations have been implemented. The basic concentration factor file contains data for 211 different radionuclides; the dose factor files are less comprehensive. However, all files can be readily expanded. The output includes tables of concentrations and doses for individual radionuclides, as well as summaries for groups of radionuclides. Existing aquatic food chain models and the sources of currently-used generic concentration factors are briefly reviewed, and dose factors based on ICRP 2 and ICRP 26 methodologies are contrasted. (auth)
Clinical implementation of full Monte Carlo dose calculation in proton beam therapy
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Paganetti, Harald; Jiang, Hongyu; Parodi, Katia; Slopsema, Roelf; Engelsman, Martijn [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114 (United States)
2008-09-07
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
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.
[Calculation of the first dose of amikacine: evaluation of the current dosage recommendations].
Jean-Bart, E; Debeurme, G; Ducher, M; Bourguignon, L
2013-01-01
Aminoglycosides, including amikacin, are antibiotics with major interest in the management of sepsis, but with a high potential toxicity. The French national recommendations revised in 2011 recommend a dose of amikacin ranging from 15 to 30 mg/kg. The objective was to assess if such a dose interval allows reaching the efficiency target concentrations of 64 mg/L without exceeding the toxic threshold of 2.5mg/L. From a cohort of 100 patients treated with amikacin, the individual pharmacokinetic parameters were estimated using pharmacokinetic software (MM-USCPACK). Peak and residual concentrations obtained after simulated doses ranging from 15 to 30 mg/kg were estimated and compared with the effective and toxic thresholds. The optimum dose to achieve precisely the efficiency target was calculated for each patient. Patients studied had a mean age of 79 years, mean weight of 58 kg, and mean creatinine clearance of 45 mL/min. The dose of 30 mg/kg allows the achievement of an effective peak in 98.7% of patients, but led to a potentially toxic through for 72.4% of them. The optimal dose was at mean of 1264 mg, significantly different than doses calculated with weight (P<0.0001). A weak correlation was found between weight and the optimal dose. A fixed dose of 30 mg/kg seems to be effective for most patients, but often excessive and leads to a toxic residual to 72% of patients, whereas 15 mg/kg was insufficient for most patients. The low correlation between optimal dose and patient weight shows that weight does not explain fully the interindividual variability.
Applying graphics processor units to Monte Carlo dose calculation in radiation therapy
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Bakhtiari M
2010-01-01
Full Text Available We investigate the potential in using of using a graphics processor unit (GPU for Monte-Carlo (MC-based radiation dose calculations. The percent depth dose (PDD of photons in a medium with known absorption and scattering coefficients is computed using a MC simulation running on both a standard CPU and a GPU. We demonstrate that the GPU′s capability for massive parallel processing provides a significant acceleration in the MC calculation, and offers a significant advantage for distributed stochastic simulations on a single computer. Harnessing this potential of GPUs will help in the early adoption of MC for routine planning in a clinical environment.
Autoradiography-based, three-dimensional calculation of dose rate for murine, human-tumor xenografts
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A Fast Fourier Transform method for calculating the three-dimensional dose rate distribution for murine, human-tumour xenografts is outlined. The required input includes evenly-spaced activity slices which span the tumour. Numerical values in these slices are determined by quantitative 125I autoradiography. For the absorbed dose-rate calculation, we assume the activity from both 131I- and 90Y-labeled radiopharmaceuticals would be distributed as is measured with the 125I label. Two example cases are presented: an ovarian-carcinoma xenograft with an IgG 2ak monoclonal antibody and a neuroblastoma xenograft with meta-iobenzylguanidine (MIBG). (Author)
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A new model-based dose calculation algorithm is presented for kilovoltage x-rays and is tested for the cases of calculating the radiation dose from kilovoltage cone-beam CT (kV-CBCT) and 2D planar projected radiographs. This algorithm calculates the radiation dose to water-like media as the sum of primary and scattered dose components. The scatter dose is calculated by convolution of a newly introduced, empirically parameterized scatter dose kernel with the primary photon fluence. Several approximations are introduced to increase the scatter dose calculation efficiency: (1) the photon energy spectrum is approximated as monoenergetic; (2) density inhomogeneities are accounted for by implementing a global distance scaling factor in the scatter kernel; (3) kernel tilting is ignored. These approximations allow for efficient calculation of the scatter dose convolution with the fast Fourier transform. Monte Carlo simulations were used to obtain the model parameters. The accuracy of using this model-based algorithm was validated by comparing with the Monte Carlo method for calculating dose distributions for real patients resulting from radiotherapy image guidance procedures including volumetric kV-CBCT scans and 2D planar projected radiographs. For all patients studied, mean dose-to-water errors for kV-CBCT are within 0.3% with a maximum standard deviation error of 4.1%. Using a medium-dependent correction method to account for the effects of photoabsorption in bone on the dose distribution, mean dose-to-medium errors for kV-CBCT are within 3.6% for bone and 2.4% for soft tissues. This algorithm offers acceptable accuracy and has the potential to extend the applicability of model-based dose calculation algorithms from megavoltage to kilovoltage photon beams. (paper)
Dosimetric study of the effective doses resulting during dental X-ray and panoramic radiography
Shousha, Hany A.; Abd-El Hafez, A. I.; Ahmad, Fawzia
2011-01-01
The panoramic image is one of the most commonly used radiographic examinations in dentistry, owing to its low dose and large area for evaluation, including bone and teeth in the same image. Although digital images are usually reported to deliver a lower radiation dose to the patient, conventional images are still available, especially in countries where digital systems are not widely economically available. Dentists should weigh the benefits of dental radiographs against the consequences of increasing a patient's exposure to radiation, the effects of which accumulate from multiple sources over time. The "as low as reasonably achievable" principle should be followed to minimize the exposure to radiation. The purpose of this investigation is to measure the absorbed radiation doses at 12 anatomical sites of a Rando-phantom and calculate the effective doses result from a full-mouth survey and panoramic radiography. Organ-absorbed doses are measured using thermoluminescent dosimeters (TLD 100) and effective organ doses (μ Sv) are estimated according to the International Commission on Radiological Protection in 2007. The total effective dose results from the panoramic imaging system have so far been below those obtained using the full-mouth survey technique used in intra-oral radiographic examination.
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Utilization of nuclear energy to produce or generate electricity is a growing practice in the world, since it represent an economic and safe option to replace fossil fuels. During operation of nuclear power plants, radioactive materials are produced. A small fraction of these material are released to environment in the form of liquid or gaseous effluents. Estimation of radiation doses causing by effluents release has three purposes. During design phase of a nuclear station it is useful to adapt the wastes treatment systems to acceptable limits. During licensing phase, the regulator organism verifies the design of nuclear station effectuating estimation of doses. Finally, during operation of a nuclear station, before every unload of radioactive effluents, radiation doses should be evaluate in order to fulfill technical specifications, which limit the release of radioactive materials to environment. 1. To perform calculations of individual doses due to liquid radioactive effluents unload in units 1 and 2 of Laguna Verde nuclear power plant (In licensing phase). 2. To perform a parametric study of the effect of unload recirculation over individual dose, since recirculation has two principal effects: thermodynamical effects in nuclear station and radioactivity concentration, the last can affect the fullfilment of dose limits. 3. To perform the calculation of collective doses causes by unloads of liquid effluents within a radius of 80 Kms. of nuclear station caused by unload of liquid radioactive effluents during normal operation of nuclear power plant and does not include doses caused during accident conditions. In Mexico the organism in charge of regulation of peaceful uses of nuclear energy is Comision Nacional de Seguridad Nuclear y Salvaguardias (CNSNS) and for Laguna Verde licensing, the regulations of country who manufactured the reactor was adopted, it is to say United States of America. In Appendix 'C' units used along this work are explained. Unless another
Monte Carlo calculations of the depth-dose distribution in skin contaminated by hot particles
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Patau, J.-P. (Toulouse-3 Univ., 31 (France))
1991-01-01
Accurate computer programs were developed in order to calculate the spatial distribution of absorbed radiation doses in the skin, near high activity particles (''hot particles''). With a view to ascertaining the reliability of the codes the transport of beta particles was simulated in a complex configuration used for dosimetric measurements: spherical {sup 60}Co sources of 10-1000 {mu}m fastened to an aluminium support with a tissue-equivalent adhesive overlaid with 10 {mu}m thick aluminium foil. Behind it an infinite polystyrene medium including an extrapolation chamber was assumed. The exact energy spectrum of beta emission was sampled. Production and transport of secondary knock-on electrons were also simulated. Energy depositions in polystyrene were calculated with a high spatial resolution. Finally, depth-dose distributions were calculated for hot particles placed on the skin. The calculations will be continued for other radionuclides and for a configuration suited to TLD measurements. (author).
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Full text: Purpose: To discuss the findings of an investigation into uranium intake and to discuss the lessons learned from the subsequent bioassay monitoring and dose calculations. Method: An investigation was held to determine direct and root causes after elevated air concentration levels were reported during the execution of an ad-hoc task. A programme of bioassay monitoring (urine sampling and lung counts) was implemented for the involved staff and committed effective doses were calculated. Major findings of the investigation: a) Inadequate pre-task assessment led to hazards not being identified and subsequently proper control measures were not implemented; b) Inadequate localised control of contamination led to contamination of worker's clothes and faces and contamination of rest of area; c) Workers were complacent which led to a lapse in safety awareness and subsequently they removed their face masks during the task. Problems experienced with bioassay monitoring and dose calculations: a) Some bioassay samples were not taken or were given incorrectly; b) Calculating doses were difficult due to lack of information regarding date of intake; whether there were other possible intakes; and the physiochemical nature of the uranium; c) Weak correlation between predicted and actual bioassay data; d) Period between starting bioassay monitoring and the actual event was too long. Conclusions: a) Shortcomings in the control of contamination with protective clothing and during the execution of ad-hoc tasks; b) Identifying hazards and assessing it is extremely dependant on the skill and capabilities if the Radiation Protection Officers; c) Instructions to workers regarding sampling of urine and arrangements around the sampling should be very specific with only one person responsible for managing the process; d) Be aware of the psychological impact on the affected workers; e) 2 nd Independent dose calculation important for verifying doses; f) Detection capabilities and
Brugger, Markus; Assmann, R W; Forkel-Wirth, Doris; Menzel, Hans Gregor; Roesler, Stefan; Vincke, Helmut H
2005-01-01
Radiation protection of the personnel who will perform interventions in the LHC Beam Cleaning Insertions is mandatory and includes the design of equipment and the establishment of work procedures. Residual dose rates due to activated equipment are expected to reach significant values such that any maintenance has to be planned and optimized in advance. Three-dimensional maps of dose equivalent rates at different cooling times after operation of the LHC have been calculated with FLUKA. The simulations are based on an explicit calculation of induced radioactivity and of the transport of the radiation from the radioactive decay. The paper summarizes the results for the Beam Cleaning Insertions and discusses the estimation of individual and collective doses received by personnel during critical interventions, such as the exchange of a collimator or the installation of Phase 2. The given examples outline the potential and the need to optimize, in an iterative way, the design of components as well as the layout of ...
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Sampson, Andrew; Le Yi; Williamson, Jeffrey F. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)
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
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The characteristics of the epithermal neutron beam at BMRR were measured, calculated, and reported by R.G. Fairchild. This beam has already been used for animal irradiations. The authors 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
Calculation of energy spectra for the therapeutic electron beams from depth-dose curves
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In this note the algorithm for calculation of the electron energy spectrum from the depth-dose curve was tested by data on a 4 MeV linear accelerator with scanning beam. A Perspex phantom with cellulose triacetate dosimetric films was irradiated on a conveyor moving perpendicularly to the area of beam scanning, thus simulating irradiation by broad beam. Excellent agreement between measured and calculated spectra is claimed. (U.K.)
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This study aims to investigate the effects of oblique incidence, small field size and inhomogeneous media on the electron dose distribution, and to compare calculated (Elekta/CMS XiO) and measured results. All comparisons were done in terms of absolute dose. A new measuring method was developed for high resolution, absolute dose measurement of non-standard beams using Gafchromic® EBT3 film. A portable U-shaped holder was designed and constructed to hold EBT3 films vertically in a reproducible setup submerged in a water phantom. The experimental film method was verified with ionisation chamber measurements and agreed to within 2% or 1 mm. Agreement between XiO electron Monte Carlo (eMC) and EBT3 was within 2% or 2 mm for most standard fields and 3% or 3 mm for the non-standard fields. Larger differences were seen in the build-up region where XiO eMC overestimates dose by up to 10% for obliquely incident fields and underestimates the dose for small circular fields by up to 5% when compared to measurement. Calculations with inhomogeneous media mimicking ribs, lung and skull tissue placed at the side of the film in water agreed with measurement to within 3% or 3 mm. Gafchromic film in water proved to be a convenient high spatial resolution method to verify dose distributions from electrons in non-standard conditions including irradiation in inhomogeneous media. (paper)
Calculation of neutron fluence-to-dose conversion factors for extremities
International Nuclear Information System (INIS)
The Pacific Northwest Laboratory is developing a standard for the performance testing of personnel extremity dosimeters for the US Department of Energy. Part of this effort requires the calculation of neutron fluence-to-dose conversion factors for finger and wrist extremities. This study focuses on conversion factors for two types of extremity models: namely the polymethyl methacrylate (PMMA) phantom (as specified in the draft standard for performance testing of extremity dosimeters) and more realistic extremity models composed of tissue-and-bone. Calculations for each type of model are based on both bare and D2O-moderated 252Cf sources. The results are then tabulated and compared with whole-body conversion factors. More appropriate energy-averaged quality factors for the extremity models have also been computed from the neutron fluence in 50 equally spaced energy bins with energies from 2.53 x 10-8 to 15 MeV. Tabulated results show that conversion factors for both types of extremity phantom are 15 to 30% lower than the corresponcung whole-body phantom conversion factors for 252Cf neutron sources. This difference in extremity and whole-body conversion factors is attributable to the proportionally smaller amount of back-scattering that occurs in the extremity phantoms compared with whole-body phantoms
Dose calculation accuracy using cone-beam CT (CBCT) for pelvic adaptive radiotherapy
Guan, Huaiqun; Dong, Hang
2009-10-01
This study is to evaluate the dose calculation accuracy using Varian's cone-beam CT (CBCT) for pelvic adaptive radiotherapy. We first calibrated the Hounsfield Unit (HU) to electron density (ED) for CBCT using a mini CT QC phantom embedded into an IMRT QA phantom. We then used a Catphan 500 with an annulus around it to check the calibration. The combined CT QC and IMRT phantom provided correct HU calibration, but not Catphan with an annulus. For the latter, not only was the Teflon an incorrect substitute for bone, but the inserts were also too small to provide correct HUs for air and bone. For the former, three different scan ranges (6 cm, 12 cm and 20.8 cm) were used to investigate the HU dependence on the amount of scatter. To evaluate the dose calculation accuracy, CBCT and plan-CT for a pelvic phantom were acquired and registered. The single field plan, 3D conformal and IMRT plans were created on both CT sets. Without inhomogeneity correction, the two CT generated nearly the same plan. With inhomogeneity correction, the dosimetric difference between the two CT was mainly from the HU calibration difference. The dosimetric difference for 6 MV was found to be the largest for the single lateral field plan (maximum 6.7%), less for the 3D conformal plan (maximum 3.3%) and the least for the IMRT plan (maximum 2.5%). Differences for 18 MV were generally 1-2% less. For a single lateral field, calibration with 20.8 cm achieved the minimum dosimetric difference. For 3D and IMRT plans, calibration with a 12 cm range resulted in better accuracy. Because Catphan is the standard QA phantom for the on-board imager (OBI) device, we specifically recommend not using it for the HU calibration of CBCT.
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.
Accuracy of out-of-field dose calculations by a commercial treatment planning system
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Howell, Rebecca M; Scarboro, Sarah B; Kry, S F; Yaldo, Derek Z, E-mail: Rhowell@mdanderson.or [University of Texas Health Science Center Houston, Graduate School of Biomedical Sciences, Houston, TX 77030 (United States)
2010-12-07
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.
Accuracy of out-of-field dose calculations by a commercial treatment planning system
Howell, Rebecca M.; Scarboro, Sarah B.; Kry, S. F.; Yaldo, Derek Z.
2010-12-01
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.
International Nuclear Information System (INIS)
In this paper we present the results of our calculations of the OECD NEA benchmark on generation-IV advanced sodium-cooled fast reactor (SFR) concepts. The aim of this benchmark is to study the core design features, moreover the feedback and transient behaviour of four SFR concepts. At the present state, static global neutronic parameters, e.g. keff, effective delayed neutron fraction, Doppler constant, sodium void worth, control rod worth, power distribution; and burnup were calculated for both the beginning and the end of cycle. In the benchmark definition, the following core descriptions were specified: two large cores (3600 MW thermal power) with carbide and oxide fuel, and two medium cores (1000 MW thermal power) with metal and oxide fuel. The calculations were performed by using the ECCO module of the ERANOS code system at the subassembly level, and with the KIKO3DMG code at the core level. The former code produced the assembly homogenized cross sections applying 1968 group collision probability calculations; the latter one determined the core multiplication factor, the radial power distribution using a 3D nodal diffusion method in 9 energy groups. We examined the effects of increasing the energy groups to 17 in the core calculation. The reflector and shield assembly homogenization methodology was also tested: a “homogeneous region model” was compared with a “concentric cylindrical core” calculation. The breeding ratio was also determined for the beginning of cycle. (author)
Dose rate calculations from radioactive vascular stents: DPK versus exact MC approach
International Nuclear Information System (INIS)
Vascular stents activated with radioactive isotopes are planned to be used in clinical practice to prevent restenosis in human coronary arteries after balloon angioplasty. Medical stents are cylindrical meshes and their complex geometry is usually treated for energy dose calculation with approximate dose point kernel (DPK) approach. The important point missed in the DPK approach is the absence of the stent material and, hence, the absence of energy absorption inside the stent. We have performed a comparison between DPK and exact Monte Carlo calculations for some simplified stent models. It appears that DPK approximation significantly overestimates pike dose values especially for the case of γ-emitting sources. We suggest DPK kernel normalization, which minimizes the difference at relatively far distances, while significant discrepancies near the stent surface still remain. (orig.)
Ulmer, W
2010-01-01
We have developed a model for proton depth dose and lateral distributions based on Monte Carlo calculations (GEANT4) and an integration procedure of the 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 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 measured depth dose curves in order to describe individual characteristics of the beamline - the most important b...
Directory of Open Access Journals (Sweden)
Reda Sonia M.
2006-01-01
Full Text Available Radiation dose distributions in various parts of the body are of importance in radiotherapy. Also, the percent depth dose at different body depths is an important parameter in radiation therapy applications. Monte Carlo simulation techniques are the most accurate methods for such purposes. Monte Carlo computer calculations of photon spectra and the dose ratios at surfaces and in some internal organs of a human equivalent phantom were performed. In the present paper, dose distributions in different organs during bladder radiotherapy by 6 MeV X-rays were measured using thermoluminescence dosimetry placed at different points in the human-phantom. The phantom was irradiated in exactly the same manner as in actual bladder radiotherapy. Four treatment fields were considered to maximize the dose at the center of the target and minimize it at non-target healthy organs. All experimental setup information was fed to the MCNP-4b code to calculate dose distributions at selected points inside the proposed phantom. Percent depth dose distribution was performed. Also, the absorbed dose as ratios relative to the original beam in the surrounding organs was calculated by MCNP-4b and measured by thermoluminescence dosimetry. Both measured and calculated data were compared. Results indicate good agreement between calculated and measured data inside the phantom. Comparison between MCNP-4b calculations and measurements of depth dose distribution indicated good agreement between both.
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Sutherland, J. G. H.; Thomson, R. M.; Rogers, D. W. O. [Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa K1S 5B6 (Canada)
2011-08-15
Purpose: To investigate the use of various breast tissue segmentation models in Monte Carlo dose calculations for low-energy brachytherapy. Methods: The EGSnrc user-code BrachyDose is used to perform Monte Carlo simulations of a breast brachytherapy treatment using TheraSeed Pd-103 seeds with various breast tissue segmentation models. Models used include a phantom where voxels are randomly assigned to be gland or adipose (randomly segmented), a phantom where a single tissue of averaged gland and adipose is present (averaged tissue), and a realistically segmented phantom created from previously published numerical phantoms. Radiation transport in averaged tissue while scoring in gland along with other combinations is investigated. The inclusion of calcifications in the breast is also studied in averaged tissue and randomly segmented phantoms. Results: In randomly segmented and averaged tissue phantoms, the photon energy fluence is approximately the same; however, differences occur in the dose volume histograms (DVHs) as a result of scoring in the different tissues (gland and adipose versus averaged tissue), whose mass energy absorption coefficients differ by 30%. A realistically segmented phantom is shown to significantly change the photon energy fluence compared to that in averaged tissue or randomly segmented phantoms. Despite this, resulting DVHs for the entire treatment volume agree reasonably because fluence differences are compensated by dose scoring differences. DVHs for the dose to only the gland voxels in a realistically segmented phantom do not agree with those for dose to gland in an averaged tissue phantom. Calcifications affect photon energy fluence to such a degree that the differences in fluence are not compensated for (as they are in the no calcification case) by dose scoring in averaged tissue phantoms. Conclusions: For low-energy brachytherapy, if photon transport and dose scoring both occur in an averaged tissue, the resulting DVH for the entire
GPU-based fast Monte Carlo dose calculation for proton therapy
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.
Inaniwa, T.; Kanematsu, N.; Sato, S.; Kohno, R.
2016-01-01
In treatment planning for proton radiotherapy, the dose measured in water is applied to the patient dose calculation with density scaling by stopping power ratio {ρ\\text{S}} . Since the body tissues are chemically different from water, this approximation may cause dose calculation errors, especially due to differences in nuclear interactions. We proposed and validated an algorithm for correcting these errors. The dose in water is decomposed into three constituents according to the physical interactions of protons in water: the dose from primary protons continuously slowing down by electromagnetic interactions, the dose from protons scattered by elastic and/or inelastic interactions, and the dose resulting from nonelastic interactions. The proportions of the three dose constituents differ between body tissues and water. We determine correction factors for the proportion of dose constituents with Monte Carlo simulations in various standard body tissues, and formulated them as functions of their {ρ\\text{S}} for patient dose calculation. The influence of nuclear interactions on dose was assessed by comparing the Monte Carlo simulated dose and the uncorrected dose in common phantom materials. The influence around the Bragg peak amounted to -6% for polytetrafluoroethylene and 0.3% for polyethylene. The validity of the correction method was confirmed by comparing the simulated and corrected doses in the materials. The deviation was below 0.8% for all materials. The accuracy of the correction factors derived with Monte Carlo simulations was separately verified through irradiation experiments with a 235 MeV proton beam using common phantom materials. The corrected doses agreed with the measurements within 0.4% for all materials except graphite. The influence on tumor dose was assessed in a prostate case. The dose reduction in the tumor was below 0.5%. Our results verify that this algorithm is practical and accurate for proton radiotherapy treatment planning, and
International Nuclear Information System (INIS)
Calculations and measurements for the dose distribution in a water-filled elliptical phantom when irradiated with neutrons of different unshielded light water moderated reactors are presented. The calculations were performed by a Monte Carlo code, for the measurements activation, TL and solid state nuclear track detectors were used. It was observed that the neutron spectra do not vary significantly inside the phantom and that not only the total absorbed dose but the kerma value at a depth of 2 cm can be higher than that on the front, in our cases by a factor of about 1.2. The measurements and calculations resulted in a kerma attenuation from the front to the back of the phantom of a factor of about 5. (author)
Mathematical child phantom for the calculation of dose to the organs at risk
International Nuclear Information System (INIS)
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
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
CALDoseX: a software tool for absorbed dose calculations in diagnostic radiology
International Nuclear Information System (INIS)
Conversion coefficients (CCs) between absorbed dose to organs and tissues at risk and measurable quantities commonly used in X-ray diagnosis have been calculated for the last 30 years mostly with mathematical MIRD5-type phantoms, in which organs are represented by simple geometrical bodies, like ellipsoids, tori, truncated cylinders, etc. In contrast, voxel-based phantoms are true to nature representations of human bodies. The purpose of this study is therefore to calculate CCs for common examinations in X-ray diagnosis with the recently developed MAX06 (Male Adult voXel) and FAX06 (Female Adult voXel) phantoms for various projections and different X-ray spectra and to make these CCs available to the public through a software tool, called CALDoseX (CALculation of Dose for X-ray diagnosis). (author)
Level of natural radionuclides in foodstuffs and resultant annual ingestion radiation dose
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The natural radioactivities in three major groups of foodstuff widely consumed in Upper Egypt were determined. The specific activities of 226Ra, 232Th, and 40K in cereals, leguminosae, and flour were measured using γ-ray spectroscopy. Another group of hay, water, and soil samples from the same location were also analyzed. Hay samples were found to contain the highest radioactivity concentration among all the samples that were investigated. This increment could be due to the high water content in the shoots which tends to accumulate soluble radionuclides. The average calculated concentrations of soil samples in the present study exhibits the lowest values with respect to those from different countries. In the case of water samples, the average activities of both 232Th and 40K were similar to those for soil while 226Ra was twice that of water sample. The annual ingestion dose from each radionuclide was calculated. The computed annual dose owing to daily intake of radium, thorium, and potassium via wheat flour, lentils,and bean in the present study (214.8 μSv) is ten times lower than the global average annual radiation dose (2400 μSv)from the natural radiation sources as proposed by UNSCEAR. The obtained results show that the dose values are quite low and carry insignificant radiation dose to the public.
Investigation of geometrical and scoring grid resolution for Monte Carlo dose calculations for IMRT
DeSmedt, B.; Vanderstraeten, B.; Reynaert, N.; DeNeve, W.; Thierens, H.
2005-09-01
Monte Carlo based treatment planning of two different patient groups treated with step-and-shoot IMRT (head-and-neck and lung treatments) with different CT resolutions and scoring methods is performed to determine the effect of geometrical and scoring voxel sizes on DVHs and calculation times. Dose scoring is performed in two different ways: directly into geometrical voxels (or in a number of grouped geometrical voxels) or into scoring voxels defined by a separate scoring grid superimposed on the geometrical grid. For the head-and-neck cancer patients, more than 2% difference is noted in the right optical nerve when using voxel dimensions of 4 × 4 × 4 mm3 compared to the reference calculation with 1 × 1 × 2 mm3 voxel dimensions. For the lung cancer patients, 2% difference is noted in the spinal cord when using voxel dimensions of 4 × 4 × 10 mm3 compared to the 1 × 1 × 5 mm3 calculation. An independent scoring grid introduces several advantages. In cases where a relatively high geometrical resolution is required and where the scoring resolution is less important, the number of scoring voxels can be limited while maintaining a high geometrical resolution. This can be achieved either by grouping several geometrical voxels together into scoring voxels or by superimposing a separate scoring grid of spherical voxels with a user-defined radius on the geometrical grid. For the studied lung cancer cases, both methods produce accurate results and introduce a speed increase by a factor of 10-36. In cases where a low geometrical resolution is allowed, but where a high scoring resolution is required, superimposing a separate scoring grid on the geometrical grid allows a reduction in geometrical voxels while maintaining a high scoring resolution. For the studied head-and-neck cancer cases, calculations performed with a geometrical resolution of 2 × 2 × 2 mm3 and a separate scoring grid containing spherical scoring voxels with a radius of 2 mm produce accurate results
Evolution of calculation models for the proton-therapy dose planning software
International Nuclear Information System (INIS)
This work was achieved in collaboration between the Institut Curie Proton-therapy Center of Orsay (ICPO), the DOSIsoft company and the CREATIS laboratory, in order to develop a new dose calculation model for the new ICPO treatment room. A new accelerator and gantry room from the IBA company were installed during the up-grade project of the proton-therapy center, with the intention of enlarging the cancer localizations treated at ICPO. Developing a package of methods and new dose calculation algorithms to adapt them to the new specific characteristics of the delivered beams by the IBA system is the first goal of this PhD work. They all aim to be implemented in the DOSIsoft treatment planning software, Isogray. First, the double scattering technique is treated in taking into account major differences between the IBA system and the ICPO fixed beam lines passive system. Secondly, a model is explored for the scanned beams modality. The second objective of this work is improving the Ray-Tracing and Pencil-Beam dose calculation models already in use. For the double scattering and uniform scanning techniques, the patient personalized collimator at the end of the beam line causes indeed a patient dose distribution contamination. A reduction method of that phenomenon was set up for the passive beam system. An analytical model was developed which describes the contamination function with parameters validated through Monte-Carlo simulations on the GATE platform. It allows us to apply those methods to active scanned beams. (author)
International Nuclear Information System (INIS)
High-energy linacs produce secondary particles such as neutrons (photoneutron production). The neutrons have the important role during treatment with high energy photons in terms of protection and dose escalation. In this work, neutron dose equivalents of 18 MV Varian and Elekta accelerators are measured by thermoluminescent dosimeter (TLD) 600 and TLD700 detectors and compared with the Monte Carlo calculations. For neutron and photon dose discrimination, first TLDs were calibrated separately by gamma and neutron doses. Gamma calibration was carried out in two procedures; by standard 60Co source and by 18 MV linac photon beam. For neutron calibration by 241Am-Be source, irradiations were performed in several different time intervals. The Varian and Elekta linac heads and the phantom were simulated by the MCNPX code (v. 2.5). Neutron dose equivalent was calculated in the central axis, on the phantom surface and depths of 1, 2, 3.3, 4, 5, and 6 cm. The maximum photoneutron dose equivalents which calculated by the MCNPX code were 7.06 and 2.37 mSv.Gy-1 for Varian and Elekta accelerators, respectively, in comparison with 50 and 44 mSv.Gy-1 achieved by TLDs. All the results showed more photoneutron production in Varian accelerator compared to Elekta. According to the results, it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry inside the linac field due to high photon flux, while MCNPX code is an appropriate alternative for studying photoneutron production. (author)
International Nuclear Information System (INIS)
A computer code TERFOC-N has bee developed to calculate doses to the public due to atmospheric releases of radionuclides in normal operations of nuclear facilities. The code calculates the highest individual dose and the collective dose from four exposure pathways; internal doses due to ingestion and inhalation, external doses due to cloudshine and groundshine. A foodchain model, which is originally referred to the U.S.NRC Regulatory Guide 1.109, has been improved to apply to not only LWRs but also other nuclear facilities. This report describes the models employed and gives a sample run performed by the code. The parameters which were sensitive to ingestion dose were identified from the results of sensitivity analysis. The models which significantly contributed to the dose were identified among the models improved and extended here. (author)
International Nuclear Information System (INIS)
Purpose: To investigate the use of the linear Boltzmann transport equation as a dose calculation tool which can account for interface effects, while still having faster computation times than Monte Carlo methods. In particular, we introduce a forward scattering approximation, in hopes of improving calculation time without a significant hindrance to accuracy. Methods: Two coupled Boltzmann transport equations were constructed, one representing the fluence of photons within the medium, and the other, the fluence of electrons. We neglect the scattering term within the electron transport equation, resulting in an extreme forward scattering approximation to reduce computational complexity. These equations were then solved using a numerical technique for solving partial differential equations, known as a finite difference scheme, where the fluence at each discrete point in space is calculated based on the fluence at the previous point in the particle's path. Using this scheme, it is possible to develop a solution to the Boltzmann transport equations by beginning with boundary conditions and iterating across the entire medium. The fluence of electrons can then be used to find the dose at any point within the medium. Results: Comparisons with Monte Carlo simulations indicate that even simplistic techniques for solving the linear Boltzmann transport equation yield expected interface effects, which many popular dose calculation algorithms are not capable of predicting. Implementation of a forward scattering approximation does not appear to drastically reduce the accuracy of this algorithm. Conclusion: Optimized implementations of this algorithm have been shown to be very accurate when compared with Monte Carlo simulations, even in build up regions where many models fail. Use of a forward scattering approximation could potentially give a reasonably accurate dose distribution in a shorter amount of time for situations where a completely accurate dose distribution is not
Sato, Tatsuhiko; Endo, Akira; Niita, Koji
2010-04-01
The fluence to organ-absorbed-dose and effective-dose conversion coefficients for heavy ions with atomic numbers up to 28 and energies from 1 MeV/nucleon to 100 GeV/nucleon were calculated using the PHITS code coupled to the ICRP/ICRU adult reference computational phantoms, following the instruction given in ICRP Publication 103 (2007 (Oxford: Pergamon)). The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. The calculation results indicate that the effective dose can generally give a conservative estimation of the effective dose equivalent for heavy-ion exposure, although it is occasionally too conservative especially for high-energy lighter-ion irradiations. It is also found from the calculation that the conversion coefficients for the Q(y)-based effective dose equivalents are generally smaller than the corresponding Q(L)-based values because of the conceptual difference between LET and y as well as the numerical incompatibility between the Q(L) and Q(y) relationships. The calculated data of these dose conversion coefficients are very useful for the dose estimation of astronauts due to cosmic-ray exposure.
International Nuclear Information System (INIS)
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. - Highlights: ► This study presents a series of simulations to determine scatter-dose in IR. ► Irradiation of the worker is non-uniform and a part of his body is shielded. ► With the CCs it is possible to estimate the occupational doses in the CA examination. ► Protection of medical personnel in IR is an important issue of radiological protection
VERIFICATION OF TORSIONAL OSCILLATING MECHANICAL SYSTEM DYNAMIC CALCULATION RESULTS
Directory of Open Access Journals (Sweden)
Peter KAŠŠAY
2014-09-01
Full Text Available On our department we deal with optimization and tuning of torsional oscillating mechanical systems. When solving these problems we often use results of dynamic calculation. The goal of this article is to compare values obtained by computation and experimentally. For this purpose, a mechanical system built in our laboratory was used. At first, classical HARDY type flexible coupling has been applied into the system, then we used a pneumatic flexible shaft coupling developed by us. The main difference of these couplings over conventional flexible couplings is that they can change their dynamic properties during operation, by changing the pressure of the gaseous medium in their flexible elements.
Volumic activities measurements and equivalent doses calculation of indoor 222Rn in Morocco
Directory of Open Access Journals (Sweden)
Abdelmajid Choukri
2015-09-01
Full Text Available Purpose: As a way of prevention, we have measured the volumic activities of indoor 222Rn and we have calculated the corresponding effective dose in some dwellings and enclosed areas in Morocco. Seasonal variation of Radon activities and Relationships between variation of these activities and some parameters such height, depth and type of construction were also established in this work.Methods: The passive time-integrated method of using a solid state nuclear track detector (LR-115 type II was employed. These films, cut in pieces of 3.4 ´ 2.5 cm2, were placed in detector holders and enclosed in heat-scaled polyethylene bags.Results: The measured volumic activities of radon vary in houses, between 31 and 136 Bq/m3 (0.55 and 2.39 mSv/year with an average value of 80 Bq/m3 (1.41 mSv/year. In enclosed work area, they vary between 60 Bq/m3 (0.38 mSv/year in an ordinary area to 1884 Bq/m3 (11.9 mSv/year at not airy underground level of 12 m. the relatively higher volumic activities of 222Rn in houses were measured in Youssoufia and khouribga towns situated in regions rich in phosphate deposits. Measurements at the geophysical observatory of Berchid show that the volumic activity of radon increases with depth, this is most probably due to decreased ventilation. Conclusion: The obtained results show that the effective dose calculated for indoor dwellings are comparable to those obtained in other regions in the word. The risks related to the volumic activities of indoor radon could be avoided by simple precautions such the continuous ventilation. The reached high value of above 1884 Bq/m3 don't present any risk for workers health in the geophysical observatory of Berchid because workers spend only a few minutes by day in the cellar to control and reregister data.
Energy Technology Data Exchange (ETDEWEB)
Egan, A [Oregon State University, Portland, OR (United States); Laub, W [Oregon Health and Science University (United States)
2014-06-15
Purpose: Several shortcomings of the current implementation of the analytic anisotropic algorithm (AAA) may lead to dose calculation errors in highly modulated treatments delivered to highly heterogeneous geometries. Here we introduce a set of dosimetric error predictors that can be applied to a clinical treatment plan and patient geometry in order to identify high risk plans. Once a problematic plan is identified, the treatment can be recalculated with more accurate algorithm in order to better assess its viability. Methods: Here we focus on three distinct sources dosimetric error in the AAA algorithm. First, due to a combination of discrepancies in smallfield beam modeling as well as volume averaging effects, dose calculated through small MLC apertures can be underestimated, while that behind small MLC blocks can overestimated. Second, due the rectilinear scaling of the Monte Carlo generated pencil beam kernel, energy is not properly transported through heterogeneities near, but not impeding, the central axis of the beamlet. And third, AAA overestimates dose in regions very low density (< 0.2 g/cm{sup 3}). We have developed an algorithm to detect the location and magnitude of each scenario within the patient geometry, namely the field-size index (FSI), the heterogeneous scatter index (HSI), and the lowdensity index (LDI) respectively. Results: Error indices successfully identify deviations between AAA and Monte Carlo dose distributions in simple phantom geometries. Algorithms are currently implemented in the MATLAB computing environment and are able to run on a typical RapidArc head and neck geometry in less than an hour. Conclusion: Because these error indices successfully identify each type of error in contrived cases, with sufficient benchmarking, this method can be developed into a clinical tool that may be able to help estimate AAA dose calculation errors and when it might be advisable to use Monte Carlo calculations.
Results of dose sensors measurements in the middle-Earth orbit for the period of 2009-2015
Protopopov, Grigory; Shatov, Pavel; Tasenko, Sergey; Lyakhov, Igor; Makarova, Nina; Balashov, Sergey; Sitnikova, Ninel
2016-07-01
The measurements results of space radiation exposure on electronic components carried out by dose sensors are presented in the paper. Dose sensors operate on metal-nitride-oxide-semiconductor dosimetry pricniple. The flight data have been receiving for more than 6 years. The measurements results are compared with others flight data on different orbits. The analysis of the received data from 2009 to 2015 allows us to find out the periods with sharp increase of dose rate and to define values of such increases. We had analyzed space radiation characteristics data from other monitoring systems (such as GOES, Electro-L) in dates of dose rate sharp increase. Results of the analysis of dose rate increase, which had been fixed by TID sensors in 2015, will be presented in full paper. We had calculated average dose rates for different space models in the middle-Earth orbit (AE8, AE9 and others) and determined the most relevant models to the experimental data (with account for relaxation effect of dose sensor outputs). The comparison results for different models will be presented in the full paper. We had used different approaches for simulating of dose sensors shielding geometry, such as semi-sphere, semi-infinite plate, sector analysis, with taking account of different shielding elements. The analysis results of shielding configuration influence on calculated values of dose rate will be presented in the full paper.
International Nuclear Information System (INIS)
ACRO was developed as a computer program to calculate internal exposure doses resulting from acute or chronic inhalation and oral ingestion of radionuclides. The ICRP Task Force Lung Model (TGLM) was used as the inhalation model in ACRO, and a simple one-compartment model was used as the ingestion model. The program is written in FORTRAN IV, and it requires about 260 KB memory capacity
GPUMCD: a new GPU-oriented Monte Carlo dose calculation platform
Hissoiny, Sami; Ozell, Benoît; Després, Philippe
2011-01-01
Purpose: Monte Carlo methods are considered the gold standard for dosimetric computations in radiotherapy. Their execution time is however still an obstacle to the routine use of Monte Carlo packages in a clinical setting. To address this problem, a completely new, and designed from the ground up for the GPU, Monte Carlo dose calculation package for voxelized geometries is proposed: GPUMCD. Method : GPUMCD implements a coupled photon-electron Monte Carlo simulation for energies in the range 0.01 MeV to 20 MeV. An analogue simulation of photon interactions is used and a Class II condensed history method has been implemented for the simulation of electrons. A new GPU random number generator, some divergence reduction methods as well as other optimization strategies are also described. GPUMCD was run on a NVIDIA GTX480 while single threaded implementations of EGSnrc and DPM were run on an Intel Core i7 860. Results : Dosimetric results obtained with GPUMCD were compared to EGSnrc. In all but one test case, 98% o...
The calculation of radial dose from heavy ions: predictions of biological action cross sections
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
The calculation of radial dose from heavy ions: predictions of biological action cross sections
Katz, Robert; Cucinotta, Francis A.; Zhang, C. X.
1996-02-01
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 γ rays (modeled from biological target theory) onto the radial dose distribution from δ 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 δ 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 penetration
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Gomes, Renato G.; Rebello, Wilson F.; Vellozo, Sergio O.; Junior, Luis M., E-mail: renatoguedes@ime.eb.br, E-mail: rebello@ime.eb.br, E-mail: vellozo@cbpf.br, E-mail: luisjrmoreira@hotmail.com [Instituto Militar de Engenharia (IME), Janeiro, RJ (Brazil); Vital, Helio C., E-mail: vital@ctex.eb.br [Centro Tecnologico do Exercito (CTEx), Barra de Guaratiba, RJ (Brazil); Rusin, Tiago, E-mail: tiago.rusin@mma.gov.br [Ministerio do Meio Ambiente, Brasilia, DF (Brazil); Silva, Ademir X., E-mail: ademir@con.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)
2013-07-01
MCNPX simulations have been performed in order to calculate dose rates as well as spectra along the four experimental channels of the gamma irradiating facility at the Technology Center of the Brazilian Army (CTEx). Safety, operational and research requirements have led to the need to determine both the magnitude and spectra of the leaking gamma fluxes. The CTEx experimental facility is cavity type with a moveable set of 28 horizontally positioned rods, filled with Cesium-137 chloride and doubly encased in stainless steel that yields an approximately plane 42 kCi-source that provides a maximum dose rate of about 1.5 kG/h into two irradiating chambers. The channels are intended for irradiation tests outside facility. They would allow larger samples to be exposed to lower gamma dose rates under controlled conditions. Dose rates have been calculated for several positions inside the channels as well as at their exits. In addition, for purposes related to the safety of operators and personnel, the angles submitted by the exiting beams have also been evaluated as they spread when leaving the channels. All calculations have been performed by using a computational model of the CTEx facility that allows its characteristics and operation to be accurately simulated by using the Monte Carlo Method. Virtual dosimeters filled with Fricke (ferrous sulfate) were modeled and positioned throughout 2 vertical channels (top and bottom) and 2 horizontal ones (front and back) in order to map dose rates and gamma spectrum distributions. The calculations revealed exiting collimated beams in the order of tenths of Grays per minute as compared to the maximum 25 Gy / min dose rate in the irradiator chamber. In addition, the beams leaving the two vertical channels were found to exhibit a widespread cone-shaped distribution with aperture angle ranging around 85 deg. The data calculated in this work are intended for use in the design of optimized experiments (better positioning of samples and
X/Qs and unit dose calculations for Central Waste Complex interim safety basis effort
International Nuclear Information System (INIS)
The objective for this problem is to calculate the ground-level release dispersion factors (X/Q) and unit doses for onsite facility and offsite receptors at the site boundary and at Highway 240 for plume meander, building wake effect, plume rise, and the combined effect. The release location is at Central Waste Complex Building P4 in the 200 West Area. The onsite facility is located at Building P7. Acute ground level release 99.5 percentile dispersion factors (X/Q) were generated using the GXQ. The unit doses were calculated using the GENII code. The dimensions of Building P4 are 15 m in W x 24 m in L x 6 m in H
GPU-based fast Monte Carlo simulation for radiotherapy dose calculation
Jia, Xun; Graves, Yan Jiang; Folkerts, Michael; Jiang, Steve B
2011-01-01
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 towards the development a 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 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. High performance random number generator and hardware linear interpolation are also utilized. We have also developed various components to hand...
BNCT dose calculation in irregular fields using the sector integration method
Energy Technology Data Exchange (ETDEWEB)
Blaumann, H.R. E-mail: blaumann@cab.cnea.gov.ar; Sanz, D.E.; Longhino, J.M.; Larrieu, O.A. Calzetta
2004-11-01
Irregular fields for boron neutron capture therapy (BNCT) have been already proposed to spare normal tissue in the treatment of superficial tumors. This added dependence would require custom measurements and/or to have a secondary calculation system. As a first step, we implemented the sector-integration method for irregular field calculation in a homogeneous medium and on the central beam axis. The dosimetric responses (fast neutron and photon dose and thermal neutron flux), are calculated by sector integrating the measured responses of circular fields over the field boundary. The measurements were carried out at our BNCT facility, the RA-6 reactor (Argentina). The input data were dosimetric responses for circular fields measured at different depths in a water phantom using ionisation and activation techniques. Circular fields were formed by shielding the beam with two plates: borated polyethilene plus lead. As a test, the dosimetric responses of a 7x4 cm{sup 2} rectangular field, were measured and compared to calculations, yielding differences less than 3% in equivalent dose at any depth indicating that the tool is suitable for redundant calculations.
BNCT dose calculation in irregular fields using the sector integration method.
Blaumann, H R; Sanz, D E; Longhino, J M; Larrieu, O A Calzetta
2004-11-01
Irregular fields for boron neutron capture therapy (BNCT) have been already proposed to spare normal tissue in the treatment of superficial tumors. This added dependence would require custom measurements and/or to have a secondary calculation system. As a first step, we implemented the sector-integration method for irregular field calculation in a homogeneous medium and on the central beam axis. The dosimetric responses (fast neutron and photon dose and thermal neutron flux), are calculated by sector integrating the measured responses of circular fields over the field boundary. The measurements were carried out at our BNCT facility, the RA-6 reactor (Argentina). The input data were dosimetric responses for circular fields measured at different depths in a water phantom using ionisation and activation techniques. Circular fields were formed by shielding the beam with two plates: borated polyethilene plus lead. As a test, the dosimetric responses of a 7x4 cm(2) rectangular field, were measured and compared to calculations, yielding differences less than 3% in equivalent dose at any depth indicating that the tool is suitable for redundant calculations.
International Nuclear Information System (INIS)
In its recent recommendations the ICRP adopted two voxel models of an adult male and an adult female to be used for the forthcoming update of organ dose conversion coefficients. These voxel models are representative of an average population, i.e. they resemble the ICRP reference anatomical data with respect to their external dimensions and their organ masses and were constructed for this purpose. They will be used as the standard human models for the computation of dose conversion coefficients in occupational protection as well as for the protection of the patient and the general public. Using these new models, conversion coefficients for environmental exposures were computed. Two source geometries were simulated, exposure from a radioactive cloud and from ground contamination, by taking into account the precise angular and energy distributions of the gamma rays. The organ dose conversion coefficients were calculated using the Monte Carlo code EGSnrc simulating the photon transport in the voxel models. Furthermore, new nuclear decay data have been released by the ICRP. These have been used in order to calculate dose equivalent rates for photon exposures of several radionuclides for the above environmental exposures. (author)
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.
Effects of the difference in tube voltage of the CT scanner on dose calculation
Rhee, Dong Joo; Kim, Sung-Woo; Moon, Young Min; Kim, Jung Ki; Jeong, Dong Hyeok
2015-01-01
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, CT number, which is directly proportional to the linear attenuation coefficient, is required to be converted to electron density for radiation dose calculation for cancer treatment. However, if various tube voltages were applied to take the patient CT image without applying the specific CT number to electron density conversion curve, ...
Specific absorbed fractions and S-factors for calculating absorbed dose to embryo and fetus
International Nuclear Information System (INIS)
The variation of specific absorbed fractions from maternal tissues to embryo/fetus is investigated for four different target masses and geometries. S-factors are calculated for selected radionuclides assumed to be distributed uniformly in fetal tissues represented by spheres from 1 mg to 4 kg. As an example, the dose to fetal tissues for iodine-131 and iron-59 is estimated based on human biokinetic data for various stages of pregnancy. 24 references, 4 tables
Dose Calculations for the Co-Disposal WP-of HLW-Glass and the Triga SNF
Energy Technology Data Exchange (ETDEWEB)
G. Radulescu
1999-08-02
This calculation is prepared by the Monitored Geologic Repository (MGR) Waste Package Operations (WPO). The purpose of this calculation is to determine the surface dose rates of a codisposal waste package (WP) containing a centrally located Department of Energy (DOE) standardized 18-in. spent nuclear fuel (SNF) canister, loaded with the TRIGA (Training, Research, Isotopes, General Atomics) SNF. This canister is surrounded by five 3-m long canisters, loaded with Savannah River Site (SRS) high-level waste (HLW) glass. The results are to support the WP design and radiological analyses.
Tian, Zhen; Folkerts, Michael; Shi, Feng; Jiang, Steve B; Jia, Xun
2015-01-01
Monte Carlo (MC) simulation is considered as the most accurate method for radiation dose calculations. Accuracy of a source model for a linear accelerator is critical for the overall dose calculation accuracy. In this paper, we presented an analytical source model that we recently developed for GPU-based MC dose calculations. A key concept called phase-space-ring (PSR) was proposed. It contained a group of particles that are of the same type and close in energy and radial distance to the center of the phase-space plane. The model parameterized probability densities of particle location, direction and energy for each primary photon PSR, scattered photon PSR and electron PSR. For a primary photon PSRs, the particle direction is assumed to be from the beam spot. A finite spot size is modeled with a 2D Gaussian distribution. For a scattered photon PSR, multiple Gaussian components were used to model the particle direction. The direction distribution of an electron PSRs was also modeled as a 2D Gaussian distributi...
GPU-based ultra fast dose calculation using a finite pencil beam model
Gu, Xuejun; Men, Chunhua; Pan, Hubert; Majumdar, Amitava; Jiang, Steve B
2009-01-01
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 on a case of a water phantom and a case of a prostate cancer patient with varying beamlet and voxel sizes. All testing scenarios achieved speedup ranging from 200~400 times when using a NVIDIA Tesla C1060 card...
International Nuclear Information System (INIS)
Full text: In this study irradiation geometry applicable to PCXMC and the consequent calculation of effective dose in applications of cone beam computed tomography (CBCT) was developed. Two different CBCT equipment s for dental applications were evaluated: Care Stream Cs-9000 3-Dimensional and Gendex GXCB-500 tomographs. Each protocol initially was characterized by measuring the surface kerma input and the product air kerma-area, PKA. Then, technical parameters of each of the predetermined protocols and geometric conditions in the PCXMC software were introduced to obtain the values of effective dose. The calculated effective dose is within the range of 9.0 to 15.7 μSv for Cs 9000 3-D and in the range 44.5 to 89 mSv for GXCB-500 equipment. These values were compared with dosimetric results obtained using thermoluminescent dosimeters implanted in anthropomorphic mannequin and were considered consistent. The effective dose results are very sensitive to the radiation geometry (beam position); this represents a factor of fragility software usage, but on the other hand, turns out to be a very useful tool for quick conclusions regarding the optimization process of protocols. We can conclude that the use of Monte Carlo simulation software PCXMC is useful in the evaluation of test protocols of CBCT in dental applications. (Author)
Directory of Open Access Journals (Sweden)
Ghavami Seyed Mostafa
2016-01-01
Full Text Available Using the nano-scaled radionuclides in the radionuclide therapy significantly reduces the particles trapping in the organs vessels and avoids thrombosis formations. Additionally, uniform distribution in the target organ may be another benefit of the nanoradionuclides in the radionuclide therapy. Monte Carlo simulation was conducted to model a mathematical humanoid phantom and the liver cells of the simulated phantom were filled with the 90Y nanospheres. Healthy organs doses, fatal and nonfatal risks of the surrounding organs were estimated. The estimations and calculations were made in four different distribution patterns of the radionuclide seeds. Maximum doses and risks estimated for the surrounding organs were obtained in the high edge concentrated distribution model of the liver including the nanoradionuclides. For the dose equivalent, effective dose, fatal and non-fatal risks, the values obtained as 7.51E-03 Sv/Bq, 3.01E-01 Sv/Bq, and 9.16E-01 cases/104 persons for the bladder, colon, and kidney of the modeled phantom, respectively. The mentioned values were the maximum values among the studied modeled distributions. Maximum values of Normal Tissue Complication Probability for the healthy organs calculated as 5.9-8.9 %. Result of using nanoparticles of the 90Y provides promising dosimetric properties in MC simulation results considering non-toxicity reports for the radionuclide.
Energy Technology Data Exchange (ETDEWEB)
NONE
2011-09-15
The present ''Calculation Guide Mining'' serves to determine mining-caused radiation exposure of members of the public and of workers. It is applicable for the use, decommissioning, remediation, and reuse of mining plants and installations as well as for the use, remediation, and reuse of land contaminated as a result of mining plants and installations. The ''Calculation Guide Mining'' describes procedures and parameters to determine effective dose indoors, at underground workplaces, and outdoors, as well as for consumption of breast milk and locally produced foodstuff. The following exposure pathways are considered: external exposure due to gamma-radiation from the soil, exposure due to inhalation of dust, exposure due to inhalation of radon and its short-lived decay products, exposure from ingestion of breast milk and locally produced foodstuff (drinking water, fish, milk and milk products, meat and meat products, leafy vegetables, other vegetable products), and exposure due to direct soil ingestion. In order to account for the natural level of environmental radioactivity involved in measurements, the ''Calculation Guide Mining'' includes levels of natural background for all relevant environmental media. (orig.)
DITTY - a computer program for calculating population dose integrated over ten thousand years
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Napier, B.A.; Peloquin, R.A.; Strenge, D.L.
1986-03-01
The computer program DITTY (Dose Integrated Over Ten Thousand Years) was developed to determine the collective dose from long term nuclear waste disposal sites resulting from the ground-water pathways. DITTY estimates the time integral of collective dose over a ten-thousand-year period for time-variant radionuclide releases to surface waters, wells, or the atmosphere. This document includes the following information on DITTY: a description of the mathematical models, program designs, data file requirements, input preparation, output interpretations, sample problems, and program-generated diagnostic messages.
Austrian results from Matroshka poncho and organ dose determination
Hajek, M.; Bergmann, R.; Fugger, M.; Vana, N.
Cosmic rays in low-earth orbits LEO primarily consist of high-energy charged particles originating from galactic cosmic radiation GCR energetic solar particle events SPE and trapped radiation belts These radiations of high linear energy transfer LET generally inflict greater biological damage than that resulting from typical terrestrial radiation hazards Particle and energy spectra are attenuated in interaction processes within shielding structures and within the human body Reliable assessment of health risks to astronaut crews is pivotal in the design of future expeditions into interplanetary space and requires knowledge of absorbed radiation doses in critical radiosensitive organs and tissues The European Space Agency ESA Matroshka experiment---conducted under the aegis of the German Aerospace Center DLR ---is aimed at simulating an astronaut s body during extravehicular activities EVA Matroshka basically consists of a human phantom torso attached to a base structure and covered with a protective carbon-fibre container acting as a spacesuit model The phantom is divided into 33 tissue-equivalent polyurethane slices of specific density for tissue and organs Natural bones are embedded Channels and cut-outs enable accommodation of active and passive radiation monitors The torso is dressed by a skin-equivalent poncho which is also designed for dosimeter integration The phantom houses in total 7 active and more than 6000 passive radiation sensors Thereof the Atomic Institute of the Austrian Universities ATI provided more than
OSCAAR calculations for the Hanford dose reconstruction scenario of BIOMASS Theme 2
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Homma, Toshimitsu; Tomita, Kenichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Inoue, Yoshihisa [Visible Information Center Inc., Tokai, Ibaraki (Japan)
2000-10-01
This report presents the results obtained from the application of the accident consequence assessment code, called OSCAAR, developed in Japan Atomic Energy Research Institute to the Hanford dose reconstruction scenario of BIOMASS Theme 2 organized by International Atomic Energy Agency. The scenario relates to an inadvertent release of {sup 131}I to atmosphere from the Hanford Purex Chemical Separations Plant on 2-5 September 1963. This exercise was used to test the atmospheric dispersion and deposition models and food chain transport models for {sup 131}I in OSCAAR with actual measurements and to identify the most important sources of uncertainty with respect both to the part of the assessment and to the overall assessment. The OSCAAR food chain model performed relatively well, while the atmospheric dispersion and deposition calculations made using wind data at the release height and wind fields by simple interpolation of the surrounding surface wind data indicated limited capabilities. The Monte Carlo based uncertainty and sensitivity method linked with OSCAAR successfully demonstrated its usefulness in the scenario. The method presented here also allowed the determination of the parameters that have the most important impact in accident consequence assessments. (author)
Weather scenarios for dose calculations with incomplete meteorological data. V.I.(rev.1)
International Nuclear Information System (INIS)
This report documents a study to substantiate or modify the weather scenarios proposed by the Atomic Energy Control Board Staff Position Paper on meteorological acceptance criteria for estimating the potential radiological consequences of postulated accidents (AECB, 1982) for short-, prolonged-, and long-term releases from ground level and elevated sources. The study examined available meteorological data in Canada to determine whether the AECB-proposed scenarios are sufficiently general that they are appropriate and conservative for any potential nuclear power plant in Canada, but also realistic, i.e., not so conservative that the results of dose calculations using these scenarios would be wholly unrepresentative leading to incorrect design decisions. Three different sets of scenarios were derived using three site-specific data sets from weather stations that are representative of existing nuclear power plants in Canada. When compared, the scenarios for the three sites are not significantly different from each other, especially in terms of trends, considering that they have been based on data from widely differing meteorological regions in Canada. Conservative envelopes of the scenarios for the three sites were taken to give the recommended general weather scenario set. The recommended set was then compared with the AECB proposed scenarios. The recommended scenarios are, in general, conservative
OSCAAR calculations for the Hanford dose reconstruction scenario of BIOMASS Theme 2
International Nuclear Information System (INIS)
This report presents the results obtained from the application of the accident consequence assessment code, called OSCAAR, developed in Japan Atomic Energy Research Institute to the Hanford dose reconstruction scenario of BIOMASS Theme 2 organized by International Atomic Energy Agency. The scenario relates to an inadvertent release of 131I to atmosphere from the Hanford Purex Chemical Separations Plant on 2-5 September 1963. This exercise was used to test the atmospheric dispersion and deposition models and food chain transport models for 131I in OSCAAR with actual measurements and to identify the most important sources of uncertainty with respect both to the part of the assessment and to the overall assessment. The OSCAAR food chain model performed relatively well, while the atmospheric dispersion and deposition calculations made using wind data at the release height and wind fields by simple interpolation of the surrounding surface wind data indicated limited capabilities. The Monte Carlo based uncertainty and sensitivity method linked with OSCAAR successfully demonstrated its usefulness in the scenario. The method presented here also allowed the determination of the parameters that have the most important impact in accident consequence assessments. (author)
International Nuclear Information System (INIS)
Purpose: The purpose of this study was to estimate the accuracy of the dose calculation of On-Board Imager (Varian, Palo Alto, CA) cone beam computed tomography (CBCT) with deformable image registration (DIR), using the multilevel-threshold (MLT) algorithm and histogram matching (HM) algorithm in pelvic radiation therapy. Methods and Materials: One pelvis phantom and 10 patients with prostate cancer treated with intensity modulated radiation therapy were studied. To minimize the effect of organ deformation and different Hounsfield unit values between planning CT (PCT) and CBCT, we modified CBCT (mCBCT) with DIR by using the MLT (mCBCTMLT) and HM (mCBCTHM) algorithms. To evaluate the accuracy of the dose calculation, we compared dose differences in dosimetric parameters (mean dose [Dmean], minimum dose [Dmin], and maximum dose [Dmax]) for planning target volume, rectum, and bladder between PCT (reference) and CBCTs or mCBCTs. Furthermore, we investigated the effect of organ deformation compared with DIR and rigid registration (RR). We determined whether dose differences between PCT and mCBCTs were significantly lower than in CBCT by using Student t test. Results: For patients, the average dose differences in all dosimetric parameters of CBCT with DIR were smaller than those of CBCT with RR (eg, rectum; 0.54% for DIR vs 1.24% for RR). For the mCBCTs with DIR, the average dose differences in all dosimetric parameters were less than 1.0%. Conclusions: We evaluated the accuracy of the dose calculation in CBCT, mCBCTMLT, and mCBCTHM with DIR for 10 patients. The results showed that dose differences in Dmean, Dmin, and Dmax in mCBCTs were within 1%, which were significantly better than those in CBCT, especially for the rectum (P<.05). Our results indicate that the mCBCTMLT and mCBCTHM can be useful for improving the dose calculation for adaptive radiation therapy
International Nuclear Information System (INIS)
The specific purpose of the study was to determine the experimental ratio between the reading of dosimeters used by the personnel of the Embalse nuclear power plant and the 'real' dose absorbed by the worker in different organs. An anthropomorphic phantom ALDERSON internal and externally loaded with approximately 150 TLD crystals was used. This phantom was placed in five enclosures that were usually occupied by workers of the Embalse nuclear power plant. In this way, the average dose per organ and the effective equivalent dosis in each enclosure could be calculated and compared with the personal dosimeters placed over the thorax and the conversion factor rem/rem for each enclosure was determined. The average factor resulting from the five considered enclosures was 0.73 rem/rem. This means that the personal dosimeters over value the real dosis absorbed by the personnel of the Embalse nuclear power plant in approximately 37%. (Author)
Energy Technology Data Exchange (ETDEWEB)
Kim, Min Joo; Lee, Seu Ran; Suh, Tae Suk [Dept. of Biomedical Engineering, The Catholic University of Korea, Bucheon (Korea, Republic of)
2011-11-15
Modern radiation therapy techniques, such as Image-guided radiation therapy (IGRT), Adaptive radiation therapy (ART) has become a routine clinical practice on linear accelerators for the increase the tumor dose conformity and improvement of normal tissue sparing at the same time. For these highly developed techniques, megavoltage cone beam computed tomography (MVCBCT) system produce volumetric images at just one rotation of the x-ray beam source and detector on the bottom of conventional linear accelerator for real-time application of patient condition into treatment planning. MV CBCT image scan be directly registered to a reference CT data set which is usually kilo-voltage fan-beam computed tomography (kVFBCT) on treatment planning system and the registered image scan be used to adjust patient set-up error. However, to use MV CBCT images in radiotherapy, reliable electron density (ED) distribution are required. Patients scattering, beam hardening and softening effect caused by different energy application between kVCT, MV CBCT can cause cupping artifacts in MV CBCT images and distortion of Houns field Unit (HU) to ED conversion. The goal of this study, for reliable application of MV CBCT images into dose calculation, MV CBCT images was modified to correct distortion of HU to ED using the relationship of HU and ED from kV FBCT and MV CBCT images. The HU-density conversion was performed on MV CBCT image set using Dose difference map was showing in Figure 1. Finally, percentage differences above 3% were reduced depending on applying density calibration method. As a result, total error co uld be reduced to under 3%. The present study demonstrates that dose calculation accuracy using MV CBCT image set can be improved my applying HU-density conversion method. The dose calculation and comparison of dose distribution from MV CBCT image set with/without HU-density conversion method was performed. An advantage of this study compared to other approaches is that HU
Patient-dependent beam-modifier physics in Monte Carlo photon dose calculations.
Schach von Wittenau, A E; Bergstrom, P M; Cox, L J
2000-05-01
Model pencil-beam on slab calculations are used as well as a series of detailed calculations of photon and electron output from commercial accelerators to quantify level(s) of physics required for the Monte Carlo transport of photons and electrons in treatment-dependent beam modifiers, such as jaws, wedges, blocks, and multileaf collimators, in photon teletherapy dose calculations. The physics approximations investigated comprise (1) not tracking particles below a given kinetic energy, (2) continuing to track particles, but performing simplified collision physics, particularly in handling secondary particle production, and (3) not tracking particles in specific spatial regions. Figures-of-merit needed to estimate the effects of these approximations are developed, and these estimates are compared with full-physics Monte Carlo calculations of the contribution of the collimating jaws to the on-axis depth-dose curve in a water phantom. These figures of merit are next used to evaluate various approximations used in coupled photon/electron physics in beam modifiers. Approximations for tracking electrons in air are then evaluated. It is found that knowledge of the materials used for beam modifiers, of the energies of the photon beams used, as well as of the length scales typically found in photon teletherapy plans, allows a number of simplifying approximations to be made in the Monte Carlo transport of secondary particles from the accelerator head and beam modifiers to the isocenter plane.
Tissue decomposition from dual energy CT data for MC based dose calculation in particle therapy
Energy Technology Data Exchange (ETDEWEB)
Hünemohr, Nora, E-mail: n.huenemohr@dkfz.de; Greilich, Steffen [Medical Physics in Radiation Oncology, German Cancer Research Center, 69120 Heidelberg (Germany); Paganetti, Harald; Seco, Joao [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Jäkel, Oliver [Medical Physics in Radiation Oncology, German Cancer Research Center, 69120 Heidelberg, Germany and Department of Radiation Oncology and Radiation Therapy, University Hospital of Heidelberg, 69120 Heidelberg (Germany)
2014-06-15
Purpose: The authors describe a novel method of predicting mass density and elemental mass fractions of tissues from dual energy CT (DECT) data for Monte Carlo (MC) based dose planning. Methods: The relative electron density ϱ{sub e} and effective atomic number Z{sub eff} are calculated for 71 tabulated tissue compositions. For MC simulations, the mass density is derived via one linear fit in the ϱ{sub e} that covers the entire range of tissue compositions (except lung tissue). Elemental mass fractions are predicted from the ϱ{sub e} and the Z{sub eff} in combination. Since particle therapy dose planning and verification is especially sensitive to accurate material assignment, differences to the ground truth are further analyzed for mass density, I-value predictions, and stopping power ratios (SPR) for ions. Dose studies with monoenergetic proton and carbon ions in 12 tissues which showed the largest differences of single energy CT (SECT) to DECT are presented with respect to range uncertainties. The standard approach (SECT) and the new DECT approach are compared to reference Bragg peak positions. Results: Mean deviations to ground truth in mass density predictions could be reduced for soft tissue from (0.5±0.6)% (SECT) to (0.2±0.2)% with the DECT method. Maximum SPR deviations could be reduced significantly for soft tissue from 3.1% (SECT) to 0.7% (DECT) and for bone tissue from 0.8% to 0.1%. MeanI-value deviations could be reduced for soft tissue from (1.1±1.4%, SECT) to (0.4±0.3%) with the presented method. Predictions of elemental composition were improved for every element. Mean and maximum deviations from ground truth of all elemental mass fractions could be reduced by at least a half with DECT compared to SECT (except soft tissue hydrogen and nitrogen where the reduction was slightly smaller). The carbon and oxygen mass fraction predictions profit especially from the DECT information. Dose studies showed that most of the 12 selected tissues would
The MARS15-based FermiCORD code system for calculation of the accelerator-induced residual dose
Grebe, A; Lu, T; Mokhov, N; Pronskikh, V
2016-01-01
The FermiCORD code system, a set of codes based on MARS15 that calculates the accelerator-induced residual doses at experimental facilities of arbitrary configurations, has been developed. FermiCORD is written in C++ as an add-on to Fortran-based MARS15. The FermiCORD algorithm consists of two stages: 1) simulation of residual doses on contact with the surfaces surrounding the studied location and of radionuclide inventories in the structures surrounding those locations using MARS15, and 2) simulation of the emission of the nuclear decay gamma-quanta by the residuals in the activated structures and scoring the prompt doses of these gamma-quanta at arbitrary distances from those structures. The FermiCORD code system has been benchmarked against similar algorithms based on other code systems and showed a good agreement. The code system has been applied for calculation of the residual dose of the target station for the Mu2e experiment and the results have been compared to approximate dosimetric approaches.
International Nuclear Information System (INIS)
Radon and its progenies in the atmosphere of normal working- and living-rooms contribute to parts of the respiratory tract the highest radiation load from all the natural radioactive environment. The base of todays calculations are the lung model of the ICRP-task groups and the physiological data of the ICRP-Reference Man. Both deal extensively with the problems associated with the adult but much less consideration is given to the physiological properties of the growing organism and the resulting radiation load. Functions for age dependent parameters, comprising geometrical dimensions of lung parts as well as respiratory standards were defined. With the use of a hybrid-computer the modifying influence of several parameters of the ICRP-lung model was investigated for the compartmental deposition of decay products as well as clearance effects. Furthermore typical daily routines for various ages, ranging from newborn to adult, comprising different activities, such resting, light and heavy work and times spent indoors and outdoors were considered; this shows great influence on the minute volume. Considering all these factors dose assessments were performed, which reveiled that the doses in the respiratory tract reach a maximum value for the age between 5 and 10 years. These values exceed the corresponding dose values for adults by factors of 2 and more. Dose calculations are presented for children of various ages and compared with those of male and female adults with different life patterns
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Valdes, Gilmer, E-mail: gilmer.valdes@uphs.upenn.edu [Department of Radiation Oncology, Perelman Center for Advanced Medicine, University of Pennsylvania, Philadelphia, PA (United States); Robinson, Clifford [Department of Radiation Oncology, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO (United States); Lee, Percy [Department of Radiation Oncology, David Geffen School of Medicine, UCLA, Los Angeles, CA (United States); Morel, Delphine [Department of Biomedical Engineering, AIX Marseille 2 University, Marseille (France); Department of Medical Physics, Joseph Fourier University, Grenoble (France); Low, Daniel; Iwamoto, Keisuke S.; Lamb, James M. [Department of Radiation Oncology, David Geffen School of Medicine, UCLA, Los Angeles, CA (United States)
2015-04-01
Four-dimensional (4D) dose calculations for lung cancer radiotherapy have been technically feasible for a number of years but have not become standard clinical practice. The purpose of this study was to determine if clinically significant differences in tumor control probability (TCP) exist between 3D and 4D dose calculations so as to inform the decision whether 4D dose calculations should be used routinely for treatment planning. Radiotherapy plans for Stage I-II lung cancer were created for 8 patients. Clinically acceptable treatment plans were created with dose calculated on the end-exhale 4D computed tomography (CT) phase using a Monte Carlo algorithm. Dose was then projected onto the remaining 9 phases of 4D-CT using the Monte Carlo algorithm and accumulated onto the end-exhale phase using commercially available deformable registration software. The resulting dose-volume histograms (DVH) of the gross tumor volume (GTV), planning tumor volume (PTV), and PTV{sub setup} were compared according to target coverage and dose. The PTV{sub setup} was defined as a volume including the GTV and a margin for setup uncertainties but not for respiratory motion. TCPs resulting from these DVHs were estimated using a wide range of alphas, betas, and tumor cell densities. Differences of up to 5 Gy were observed between 3D and 4D calculations for a PTV with highly irregular shape. When the TCP was calculated using the resulting DVHs for fractionation schedules typically used in stereotactic body radiation therapy (SBRT), the TCP differed at most by 5% between 4D and 3D cases, and in most cases, it was by less than 1%. We conclude that 4D dose calculations are not necessary for most cases treated with SBRT, but they might be valuable for irregularly shaped target volumes. If 4D calculations are used, 4D DVHs should be evaluated on volumes that include margin for setup uncertainty but not respiratory motion.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Y; Zhang, J; Hu, Q; Tie, J; Wu, H [Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital ' Institute, Beijing (China); Deng, J [Department of Therapeutic Radiology, Yale University, New Haven, CT (United States)
2014-06-01
Purpose: To investigate the possibility of applying optimized scanning protocols for pediatric CT simulation by quantifying the dosimetric inaccuracy introduced by using a fixed HU to density conversion. Methods: The images of a CIRS electron density reference phantom (Model 062) were acquired by a Siemens CT simulator (Sensation Open) using the following settings of tube voltage and beam current: 120 kV/190mA (the reference protocol used to calibrate CT for our treatment planning system (TPS)); Fixed 190mA combined with all available kV: 80, 100, and 140; fixed 120 kV and various current from 37 to 444 mA (scanner extremes) with interval of 30 mA. To avoid the HU uncertainty of point sampling in the various inserts of known electron densities, the mean CT numbers of the central cylindrical volume were calculated using DICOMan software. The doses per 100 MU to the reference point (SAD=100cm, Depth=10cm, Field=10X10cm, 6MV photon beam) in a virtual cubic phantom (30X30X30cm) were calculated using Eclipse TPS (calculation model: AcurosXB-11031) by assigning the CT numbers to HU of typical materials acquired by various protocols. Results: For the inserts of densities less than muscle, CT number fluctuations of all protocols were within the tolerance of 10 HU as accepted by AAPM-TG66. For more condensed materials, fixed kV yielded stable HU with any mA combination where largest disparities were found in 1750mg/cc insert: HU{sub reference}=1801(106.6cGy), HU{sub minimum}=1799 (106.6cGy, error{sub dose}=0.00%), HU{sub maximum}=1815 (106.8cGy, error{sub dose}=0.19%). Yet greater disagreements were observed with increasing density when kV was modified: HU{sub minimum}=1646 (104.5cGy, error{sub dose}=- 1.97%), HU{sub maximum}=2487 (116.4cGy, error{sub dose}=9.19%) in 1750mg/cc insert. Conclusion: Without affecting treatment dose calculation, personalized mA optimization of CT simulator can be conducted by fixing kV for a better cost-effectiveness of imaging dose and quality
Hardware availability calculations and results of the IFMIF accelerator facility
Energy Technology Data Exchange (ETDEWEB)
Bargalló, Enric, E-mail: enric.bargallo-font@upc.edu [Fusion Energy Engineering Laboratory (FEEL), Technical University of Catalonia (UPC), Barcelona (Spain); Arroyo, Jose Manuel [Laboratorio Nacional de Fusión por Confinamiento Magnético – CIEMAT, Madrid (Spain); Abal, Javier [Fusion Energy Engineering Laboratory (FEEL), Technical University of Catalonia (UPC), Barcelona (Spain); Beauvais, Pierre-Yves; Gobin, Raphael; Orsini, Fabienne [Commissariat à l’Energie Atomique, Saclay (France); Weber, Moisés; Podadera, Ivan [Laboratorio Nacional de Fusión por Confinamiento Magnético – CIEMAT, Madrid (Spain); Grespan, Francesco; Fagotti, Enrico [Istituto Nazionale di Fisica Nucleare, Legnaro (Italy); De Blas, Alfredo; Dies, Javier; Tapia, Carlos [Fusion Energy Engineering Laboratory (FEEL), Technical University of Catalonia (UPC), Barcelona (Spain); Mollá, Joaquín; Ibarra, Ángel [Laboratorio Nacional de Fusión por Confinamiento Magnético – CIEMAT, Madrid (Spain)
2014-10-15
Highlights: • IFMIF accelerator facility hardware availability analyses methodology is described. • Results of the individual hardware availability analyses are shown for the reference design. • Accelerator design improvements are proposed for each system. • Availability results are evaluated and compared with the requirements. - Abstract: Hardware availability calculations have been done individually for each system of the deuteron accelerators of the International Fusion Materials Irradiation Facility (IFMIF). The principal goal of these analyses is to estimate the availability of the systems, compare it with the challenging IFMIF requirements and find new paths to improve availability performances. Major unavailability contributors are highlighted and possible design changes are proposed in order to achieve the hardware availability requirements established for each system. In this paper, such possible improvements are implemented in fault tree models and the availability results are evaluated. The parallel activity on the design and construction of the linear IFMIF prototype accelerator (LIPAc) provides detailed design information for the RAMI (reliability, availability, maintainability and inspectability) analyses and allows finding out the improvements that the final accelerator could have. Because of the R and D behavior of the LIPAc, RAMI improvements could be the major differences between the prototype and the IFMIF accelerator design.
Calculation of the internal radiation absorbed dose of 123I-Annexin V
International Nuclear Information System (INIS)
To estimate absorbed doses by 123I-Annexin V in human, 125I-Annexin V was used as a radiotracer for measuring the distribution of radiolabeled Annexin V in mice. The standard Medical Internal Radiation Dose (MIRD) method was used by Mirdose-3 software in dosimetry estimation. The results show that liver and kidney received 2.77 x 10-3 and 2.71 x 10-3 mGy/MBq, respectively. The red marrow received 1.78 x 10-5 mGy/MBq, and the other organs received doses between 1.5 x 10-4 and 10.5 x 10-4 mGy/MBq. The effective dose was estimated at 5.55 x 10-4 mSv/MBq. Human radiation dosimetry can be performed by the mice biodistribution data and important data for clinical safe trial of 123I-Annexin V are provided. (authors)
Calculation of effective dose in whole body in dependence of angle of collimator for photon fields
Energy Technology Data Exchange (ETDEWEB)
Fuenzalida, M. [Universidad de la Frontera, Temuco (Chile). Programa de Magister en Fisica Medica; Varon, C.; Piriz, G.; Banguero, Y.; Lozano, E.; Mancilla, C., E-mail: fisicamedica@incancer.c [Instituto Nacional del Cancer, Santiago (Chile). Unidad de Fisica Medica
2011-07-01
The objective of this work is to obtain quantifiable data of whole body effective dose for photons fields of 6 MV and 18 MV in function of the collimator angle of a Varian Clinac 21EX lineal accelerator. It has been made a variety of studies which investigate the form to reduce the dose in whole body with photons fields, specially over the potential risks and the influence of the collimator angle, as performed Stanthakis et al. [1] with the Monte Carlo method. As a result of this work, the values of whole body effective doses are higher with a 0 deg collimator than with a 90 deg collimator, and as the field size increases, the effective doses difference in whole body, between 0 deg and 90 deg collimator angle, for both energies, becomes smaller. (author)
Gu, Xuejun; Jelen, Urszula; Li, Jinsheng; Jia, Xun; Jiang, Steve B.
2011-01-01
Targeting at the development of an accurate and efficient dose calculation engine for online adaptive radiotherapy, we have implemented a finite size pencil beam (FSPB) algorithm with a 3D-density correction method on GPU. This new GPU-based dose engine is built on our previously published ultrafast FSPB computational framework. Dosimetric evaluations against Monte Carlo dose calculations are conducted on 10 IMRT treatment plans (5 head-and-neck cases and 5 lung cases). For all cases, there i...
Noise and dose modeling for pediatric CT optimization: preliminary results
International Nuclear Information System (INIS)
Full text: A Multiple Linear Regression Model was developed to predict noise and dose in computed tomography pediatric imaging for head and abdominal examinations. Relative values of Noise and Volumetric Computed Tomography Dose Index was used to estimate de model respectively. 54 images of physical phantoms were performed. Independent variables considered included: phantom diameter, tube current and kilovolts, x ray beam collimation, reconstruction diameter and equipment's post processing filters. Predicted values show good agreement with measurements, which were better in noise model (R2adjusted=0.953) than the dose model (R2adjusted=0.744). Tube current, object diameter, beam collimation and reconstruction filter were identified as the most influencing factors in models. (author)
International Nuclear Information System (INIS)
In a D-T burning fusion reactor, the radioactivity induced by the 14 MeV neutrons causes many problems. It limits personnel access to the reactor during shutdown, generates decay heat and produces radwastes. A code system THIDA had been developed in 1978 to calculate the radioactivity and dose rate around a fusion device. The THIDA system consisted of the followings: one- and two-dimensional discrete ordinates radiation transport codes; induced activity calculation code; three libraries for transmutation and decay chain data, transmutation cross sections and delayed gamma-ray emission data. The present report gives a complete description of THIDA-2, a new advanced version of the THIDA system which has the following major improvements: 1. Capability to treat three-dimensional calculation models by the use of a Monte Carlo transport code. 2. Accurate decay heat calculation following the transport of delayed gamma rays. 3. Simplification of the data input process by the use of free format scheme and closer coupling between the radiation transport codes and the induced activity calculation code. 4. Self-descriptive output format and additional plotter output. 5. Capability to calculate problems requiring larger core memory by the use of variable dimension. (author)
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.
Influence of metallic dental implants and metal artefacts on dose calculation accuracy
Energy Technology Data Exchange (ETDEWEB)
Maerz, Manuel; Koelbl, Oliver; Dobler, Barbara [Regensburg University Medical Center, Department of Radiotherapy, Regensburg (Germany)
2014-10-31
Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy. Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic trademark EBT2 films. For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029). For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques. (orig.) [German] Zahnimplantate aus Metall verursachen in Computertomographiedaten (CT) streifenfoermige Artefakte. Diese verhindern eine korrekte Zuordnung von Form und Dichteeigenschaften des Metalls und des umgebenden Gewebes. Ziel dieser Studie war es, den Einfluss von Zahnimplantaten auf die Genauigkeit der Dosisberechnung in der
Results of measurements of surface doses and penetration dose at radiography of the dentine
International Nuclear Information System (INIS)
The radiation doses at radiography of the dentine were measured by the methods of TLD and film using the radiation-shield tube which was produced by us. By using the radiation-shield tube, radiation doses were reduced to one-tenth and unnecessary radiation into the cranium was avoided. However, contrivances about shooting position and angle of x-ray incidence are necessary to be considered in addition to the improvement of the apparatus. (author)
Energy Technology Data Exchange (ETDEWEB)
Schloemer, Luc Laurent Alexander
2014-12-17
The compliance with the dose rate limits for transport and storage casks (TLB) for spent nuclear fuel from pressurised water reactors can be proved by calculation. This includes the determination of the radioactive sources and the shielding-capability of the cask. In this thesis the entire computational chain, which extends from the determination of the source terms to the final Monte-Carlo-transport-calculation is analysed and the arising uncertainties are quantified not only by benchmarks but also by variational calculi. The background of these analyses is that the comparison with measured dose rates at different TLBs shows an overestimation by the values calculated. Regarding the studies performed, the overestimation can be mainly explained by the detector characteristics for the measurement of the neutron dose rate and additionally in case of the gamma dose rates by the energy group structure, which the calculation is based on. It turns out that the consideration of the uncertainties occurring along the computational chain can lead to even greater overestimation. Concerning the dose rate calculation at cask loadings with spent uranium fuel assemblies an uncertainty of (({sup +21}{sub -28}) ±2) % (rel.) for the total gamma dose rate and of ({sup +28±23}{sub -55±4}) % (rel.) for the total neutron dose rate are estimated. For mixed-loadings with spent uranium and MOX fuel assemblies an uncertainty of ({sup +24±3}{sub -27±2}) % (rel.) for the total gamma dose rate and of ({sup +28±23}{sub -55±4}) % (rel.) for the total neutron dose rate are quantified. The results show that the computational chain has not to be modified, because the calculations performed lead to conservative dose rate predictions, even if high uncertainties at neutron dose rate measurements arise. Thus at first the uncertainties of the neutron dose rate measurement have to be decreased to enable a reduction of the overestimation of the calculated dose rate afterwards. In the present thesis
Effects of CT based Voxel Phantoms on Dose Distribution Calculated with Monte Carlo Method
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.
Effects of CT based Voxel Phantoms on Dose Distribution Calculated with Monte Carlo Method
Institute of Scientific and Technical Information of China (English)
Chen Chaobin; Huang Qunying; Wu Yican
2005-01-01
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.
International Nuclear Information System (INIS)
The external doses under various radioactive deposition conditions are assessed and the efficiencies of some simple decontamination techniques (grass cutting, vacuum sweeping, hosing of paved surfaces and roofs, and felling trees) are compared in the study. The present model has been constructed for the Finnish conditions and housing areas, using 137Cs transfer data from the Nordic and Central European studies and models. The compartment model concerns behaviour and decontamination of 137Cs in the urban environment under summer conditions. Doses to man have been calculated for wet (light rain) and dry deposition in four typical Finnish building areas: single-family wooden houses, brick terraced-houses, blocks of flats and urban office buildings. (26 refs.)
Prostate dose calculations for permanent implants using the MCNPX code and the Voxels phantom MAX
Energy Technology Data Exchange (ETDEWEB)
Reis Junior, Juraci Passos dos; Silva, Ademir Xavier da, E-mail: jjunior@con.ufrj.b, E-mail: Ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Facure, Alessandro N.S., E-mail: facure@cnen.gov.b [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)
2010-07-01
This paper presents the modeling of 80, 88 and 100 of {sup 125}I seeds, punctual and volumetric inserted into the phantom spherical volume representing the prostate and prostate phantom voxels MAX. Starting values of minimum and maximum activity, 0.27 mCi and 0.38 mCi, respectively, were simulated in the Monte Carlo code MCNPX in order to determine whether the final dose, according to the integration of the equation of decay at time t = 0 to t = {infinity} corresponds to the default value set by the AAPM 64 which is 144 Gy. The results showed that consider sources results in doses exceeding the percentage discrepancy of the default value of 200%, while volumetric consider sources result in doses close to 144 Gy. (author)
International Nuclear Information System (INIS)
In deuterium-deuterium (D-D) and deuterium-tritium (D-T) fusion plasmas neutrons are produced causing activation of JET machine components. For safe operation and maintenance it is important to be able to predict the induced activation and the resulting shut down dose rates. This requires a suitable system of codes which is capable of simulating both the neutron induced material activation during operation and the decay gamma radiation transport after shut-down in the proper 3-D geometry. Two methodologies to calculate the dose rate in fusion devices have been developed recently and applied to fusion machines, both using the MCNP Monte Carlo code. FZK has developed a more classical approach, the rigorous 2-step (R2S) system in which MCNP is coupled to the FISPACT inventory code with an automated routing. ENEA, in collaboration with the ITER Team, has developed an alternative approach, the direct 1 step method (D1S). Neutron and decay gamma transport are handled in one single MCNP run, using an ad hoc cross section library. The intention was to tightly couple the neutron induced production of a radio-isotope and the emission of its decay gammas for an accurate spatial distribution and a reliable calculated statistical error. The two methods have been used by the two Associations to calculate the dose rate in five positions of JET machine, two inside the vacuum chamber and three outside, at cooling times between 1 second and 1 year after shutdown. The same MCNP model and irradiation conditions have been assumed. The exercise has been proposed and financed in the frame of the Fusion Technological Program of the JET machine. The scope is to supply the designers with the most reliable tool and data to calculate the dose rate on fusion machines. Results showed that there is a good agreement: the differences range between 5-35%. The next step to be considered in 2003 will be an exercise in which the comparison will be done with dose-rate data from JET taken during and
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Cardan, R [UAB University of Alabama, Birmingham, Birmingham, AL (United States); Faught, A [MD Anderson Cancer Center, Houston, TX (United States); Huang, M; Benhabib, S [University of Alabama at Birmingham, Birmingham, AL (United States); Brezovich, I; Popple, R [University of Alabama Birmingham, Birmingham, AL (United States); Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)
2014-06-01
Purpose: Determine the dose calculation accuracy of a preconfigured Mobius server for use in secondary checks of a treatment planning system. Methods: 10 plans were created for irradiation on two of the IROC (formerly RPC) accreditation phantoms: 4 for the head and neck phantom and 6 for the lung phantom. The plans each were created using one of four different photon energies (6FFF, 10 FFF, 6X, and 15X) and were varied in treatment type including VMAT, step and shoot IMRT, dynamic MLC IMRT (DMLC), and conformal RT (CRT). The TLDs in the phantoms were contoured, and each plan was sent for calculation to Mobius software (Mobius Medical Systems, Houston, TX) with a default configuration. Each plan was then irradiated on the planned phantom 3 times to create an average reading across 56 TLDs. These readings were then compared against the corresponding Mobius calculation at each TLD location. Results: The mean difference (MD) normalized to the plan prescription dose between each TLD and Mobius calculation for all measurements was 0.5 ± 3.3%, with a maximum difference of 8.4%. The MD was 0.6 ± 3.8%, − 2.0 ± 1.9%, 1.7 ± 3.7%, and 1.9 ± 1.2% across the 6FFF, 10FFF, 6X and 15X energies respectively. The MD was −1.2 ± 2.3% for lung plans and 1.8 ± 3.5% for head/neck plans. Across treatment types, the MD ranged from − 1.8 ± 1.7% for CRT to 4.3 ± 2.4 % for DMLC. Conclusion: Out of the box and preconfigured, Mobius provides accurate dose calculations with respect to beam energy, treatment type, and treatment site.
Training software using virtual-reality technology and pre-calculated effective dose data.
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
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Maerz, Manuel; Mittermair, Pia; Koelbl, Oliver; Dobler, Barbara [Regensburg University Medical Center, Department of Radiotherapy, Regensburg (Germany); Krauss, Andreas [Siemens Healthcare GmbH, Forchheim (Germany)
2016-06-15
Metallic dental implants cause severe streaking artifacts in computed tomography (CT) data, which affect the accuracy of dose calculations in radiation therapy. The aim of this study was to investigate the benefit of the metal artifact reduction algorithm iterative metal artifact reduction (iMAR) in terms of correct representation of Hounsfield units (HU) and dose calculation accuracy. Heterogeneous phantoms consisting of different types of tissue equivalent material surrounding metallic dental implants were designed. Artifact-containing CT data of the phantoms were corrected using iMAR. Corrected and uncorrected CT data were compared to synthetic CT data to evaluate accuracy of HU reproduction. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated in Oncentra v4.3 on corrected and uncorrected CT data and compared to Gafchromic trademark EBT3 films to assess accuracy of dose calculation. The use of iMAR increased the accuracy of HU reproduction. The average deviation of HU decreased from 1006 HU to 408 HU in areas including metal and from 283 HU to 33 HU in tissue areas excluding metal. Dose calculation accuracy could be significantly improved for all phantoms and plans: The mean passing rate for gamma evaluation with 3 % dose tolerance and 3 mm distance to agreement increased from 90.6 % to 96.2 % if artifacts were corrected by iMAR. The application of iMAR allows metal artifacts to be removed to a great extent which leads to a significant increase in dose calculation accuracy. (orig.) [German] Metallische Implantate verursachen streifenfoermige Artefakte in CT-Bildern, welche die Dosisberechnung beeinflussen. In dieser Studie soll der Nutzen des iterativen Metall-Artefakt-Reduktions-Algorithmus iMAR hinsichtlich der Wiedergabetreue von Hounsfield-Werten (HU) und der Genauigkeit von Dosisberechnungen untersucht werden. Es wurden heterogene Phantome aus verschiedenen Arten gewebeaequivalenten Materials mit
Analysis by synthesis for estimation of dose calculation with gMOCREN and GEANT4 in medical image
International Nuclear Information System (INIS)
The use of GEANT4 simulation toolkit has increased in the radiation medical field for the design of treatment system and the calibration or validation of treatment plans. Moreover, it is used especially on calculating dose simulation using medical data for radiation therapy. However, using internal visualization tool of GEANT4 detector constructions on expressing dose result has deficiencies because it cannot display isodose line. No one has attempted to use this code to a real patient's data. Therefore, to complement this problem, using the result of gMocren that is a three-dimensional volume-visualizing tool, we tried to display a simulated dose distribution and isodose line on medical image. In addition, we have compared cross-validation on the result of gMocren and GEANT4 simulation with commercial radiation treatment planning system. We have extracted the analyzed data of dose distribution, using real patient's medical image data with a program based on Monte Carlo simulation and visualization tool for radiation isodose mapping.
Development and application of a random lung model for dose calculations in radiotherapy
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
Mura, Cameron
2016-01-01
This document attempts to clarify potential confusion regarding electrostatics calculations, specifically in the context of biomolecular structure and specifically as regards the units typically used to contour/visualize isopotential surfaces, potentials mapped onto molecular solvent-accessible surfaces, etc.
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.
Modulation index for VMAT considering both mechanical and dose calculation uncertainties
International Nuclear Information System (INIS)
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. (paper)
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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 Effluent 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 form for a number of years; the current effort simply recasts those RETS into Standard Radiological Effluent Controls for application to the ODCM. 11 tabs
Dose calculation and measurement for bremsstrahlung at BL18U beamline of SSRF
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Background: Gas bremsstrahlung is one of the most important radiation sources that needs to be taken into consideration for shielding design of beamlines at the third generation synchrotron radiation light source. Shanghai Synchrotron Radiation Facility (SSRF) is one of the third generation synchrotron radiation light source in the world. The Protein Micro-crystallography Beamline (BL18U) is one of the commissioning beamlines and is a representative insertion device beamline at SSRF. Purpose: Estimation of radiation dose induced by scattering bremsstrahlung and photoneutrons at BL18U. Methods: Dose rate distribution induced by scattering bremsstrahlung and photoneutrons at BL18U are performed by Monte Carlo simulation code FLUKA. The radiation dose was analyzed with the variation of slits size, beam current at storage ring and the vacuum. Dose rate of photons and photoneutrons at the outside of the optical enclosure of BL18U were measured by using high sensitivity photon and neutron monitors. Results: The measurement results show that the reliability of the simulation. Conclusion: The simulation and measurement methods presented in this study can be applied to evaluate the dose rate level of other beamline stations at SSRF, and provide references to the shielding design for the following beamlines at SSRF in the near future. (authors)
Brons, S; Elsässer, T; Ferrari, A; Gadioli, E; Mairani, A; Parodi, K; Sala, P; Scholz, M; Sommerer, F
2010-01-01
Monte Carlo codes are rapidly spreading among hadron therapy community due to their sophisticated nuclear/electromagnetic models which allow an improved description of the complex mixed radiation field produced by nuclear reactions in therapeutic irradiation. In this contribution results obtained with the Monte Carlo code FLUKA are presented focusing on the production of secondary fragments in carbon ion interaction with water and on CT-based calculations of absorbed and biological effective dose for typical clinical situations. The results of the simulations are compared with the available experimental data and with the predictions of the GSI analytical treatment planning code TRiP.
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Patient radiation doses received during endovascular treatment of abdominal aortic aneurysms (AAA) can be significant and give rise to both deterministic and stochastic effects. Recording of dose-area product (DAP), fluoroscopy time and number of exposures together with calculations of effective dose, were performed for 8 patients. In addition, the entrance surface dose was measured for 3 of the patients. Typically, DAPs of 340 Gycm2, fluoroscopy times of 30 minutes and 310 exposures were obtained together with maximum entrance surface doses of 1,8 Gy and effective doses of 50 mSv. Finger doses to the staff performing the procedure were in the order of a few hundred μSv. Conversion factors (effective dose/DAP) and (maximum entrance surface does/DAP) of 0,61·10-2 Gy/Gycm2 and 0,15 mSv/Gycm2 were obtained, respectively. (author)
Directory of Open Access Journals (Sweden)
Animesh
2005-01-01
Full Text Available The complexity of interactions and the nature of the approximations made in the formulation of the algorithm require that the user be familiar with the limitations of various models. As computer power keeps growing, calculation algorithms are tending more towards physically based models. The nature and quantity of the data required varies according to the model which may be either measurement based models or physical based models. Multiple dose calculation algorithm support found in XiO Treatment Planning System can be used to advantage when choice is to be made between speed and accuracy. Thus XiO allows end users generate plans accurately and quickly to optimize the delivery of radiation therapy.
Waste Isolation Pilot Plant Title I operator dose calculations. Final report, LATA report No. 90
International Nuclear Information System (INIS)
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
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Park, Y; Winey, B; Sharp, G [Massachusetts General Hospital, Boston, MA (United States)
2014-06-01
Purpose: To demonstrate feasibility of proton dose calculation on scattercorrected CBCT images for the purpose of adaptive proton therapy. Methods: Two CBCT image sets were acquired from a prostate cancer patient and a thorax phantom using an on-board imaging system of an Elekta infinity linear accelerator. 2-D scatter maps were estimated using a previously introduced CT-based technique, and were subtracted from each raw projection image. A CBCT image set was then reconstructed with an open source reconstruction toolkit (RTK). Conversion from the CBCT number to HU was performed by soft tissue-based shifting with reference to the plan CT. Passively scattered proton plans were simulated on the plan CT and corrected/uncorrected CBCT images using the XiO treatment planning system. For quantitative evaluation, water equivalent path length (WEPL) was compared in those treatment plans. Results: The scatter correction method significantly improved image quality and HU accuracy in the prostate case where large scatter artifacts were obvious. However, the correction technique showed limited effects on the thorax case that was associated with fewer scatter artifacts. Mean absolute WEPL errors from the plans with the uncorrected and corrected images were 1.3 mm and 5.1 mm in the thorax case and 13.5 mm and 3.1 mm in the prostate case. The prostate plan dose distribution of the corrected image demonstrated better agreement with the reference one than that of the uncorrected image. Conclusion: A priori CT-based CBCT scatter correction can reduce the proton dose calculation error when large scatter artifacts are involved. If scatter artifacts are low, an uncorrected CBCT image is also promising for proton dose calculation when it is calibrated with the soft-tissue based shifting.
Mohammadyari, Parvin; Faghihi, Reza; Mosleh-Shirazi, Mohammad Amin; Lotfi, Mehrzad; Rahim Hematiyan, Mohammad; Koontz, Craig; Meigooni, Ali S.
2015-12-01
Compression is a technique to immobilize the target or improve the dose distribution within the treatment volume during different irradiation techniques such as AccuBoost® brachytherapy. However, there is no systematic method for determination of dose distribution for uncompressed tissue after irradiation under compression. In this study, the mechanical behavior of breast tissue between compressed and uncompressed states was investigated. With that, a novel method was developed to determine the dose distribution in uncompressed tissue after irradiation of compressed breast tissue. Dosimetry was performed using two different methods, namely, Monte Carlo simulations using the MCNP5 code and measurements using thermoluminescent dosimeters (TLD). The displacement of the breast elements was simulated using a finite element model and calculated using ABAQUS software. From these results, the 3D dose distribution in uncompressed tissue was determined. The geometry of the model was constructed from magnetic resonance images of six different women volunteers. The mechanical properties were modeled by using the Mooney-Rivlin hyperelastic material model. Experimental dosimetry was performed by placing the TLD chips into the polyvinyl alcohol breast equivalent phantom. The results determined that the nodal displacements, due to the gravitational force and the 60 Newton compression forces (with 43% contraction in the loading direction and 37% expansion in the orthogonal direction) were determined. Finally, a comparison of the experimental data and the simulated data showed agreement within 11.5% ± 5.9%.
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Compression is a technique to immobilize the target or improve the dose distribution within the treatment volume during different irradiation techniques such as AccuBoost® brachytherapy. However, there is no systematic method for determination of dose distribution for uncompressed tissue after irradiation under compression. In this study, the mechanical behavior of breast tissue between compressed and uncompressed states was investigated. With that, a novel method was developed to determine the dose distribution in uncompressed tissue after irradiation of compressed breast tissue. Dosimetry was performed using two different methods, namely, Monte Carlo simulations using the MCNP5 code and measurements using thermoluminescent dosimeters (TLD). The displacement of the breast elements was simulated using a finite element model and calculated using ABAQUS software. From these results, the 3D dose distribution in uncompressed tissue was determined. The geometry of the model was constructed from magnetic resonance images of six different women volunteers. The mechanical properties were modeled by using the Mooney–Rivlin hyperelastic material model. Experimental dosimetry was performed by placing the TLD chips into the polyvinyl alcohol breast equivalent phantom. The results determined that the nodal displacements, due to the gravitational force and the 60 Newton compression forces (with 43% contraction in the loading direction and 37% expansion in the orthogonal direction) were determined. Finally, a comparison of the experimental data and the simulated data showed agreement within 11.5% ± 5.9%. (paper)
SU-E-T-397: Include Organ Deformation Into Dose Calculation of Prostate Brachytherapy
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Shao, Y; Shen, D; Chen, R; Wang, A; Lian, J [University of North Carolina, Chapel Hill, NC (United States)
2014-06-01
Purpose: Prostate brachytherapy is an important curative treatment for patients with localized prostate cancer. In brachytherapy, rectal balloon is generally needed to adjust for unfavorable prostate position for seed placement. However, rectal balloon causes prostate deformation, which is not accounted for in dosimetric planning. Therefore, it is possible that brachytherapy dosimetry deviates significantly from initial plan when prostate returns to its non-deformed state (after procedure). The goal of this study is to develop a method to include prostate deformation into the treatment planning of brachytherapy dosimetry. Methods: We prospectively collected ultrasound images of prostate pre- and post- rectal balloon inflation from thirty five consecutive patients undergoing I-125 brachytherapy. Based on the cylinder coordinate systems, we learned the initial coordinate transformation parameters between the manual segmentations of both deformed and non-deformed prostates of each patient in training set. With the nearest-neighbor interpolation, we searched the best transformation between two coordinate systems to maximum the mutual information of deformed and non-deformed images. We then mapped the implanted seeds of five selected patients from the deformed prostate into non-deformed prostate. The seed position is marked on original pre-inflation US image and it is imported into VariSeed software for dose calculation. Results: The accuracy of image registration is 87.5% as quantified by Dice Index. The prostate coverage V100% dropped from 96.5±0.5% of prostate deformed plan to 91.9±2.6% (p<0.05) of non-deformed plan. The rectum V100% decreased from 0.44±0.26 cc to 0.10±0.18 cc (p<0.05). The dosimetry of the urethra showed mild change but not significant: V150% changed from 0.05±0.10 cc to 0.14±0.15 cc (p>0.05) and D1% changed from 212.9±37.3 Gy to 248.4±42.8 Gy (p>0.05). Conclusion: We have developed a deformable image registration method that allows
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The aim of this study is to investigate the effect of tissue inhomogeneities when applying to contrast medium among Homogeneous, Batho and ETAR dose calculation method in RTP system. We made customized heterogeneous phantom it filled with water or contrast medium slab. Phantom scan data have taken PQ 5000 (CT scanner, Marconi, USA) and then dose was calculated in 3D RTP (AcQ-Plan, Marconi, USA) depends on dose calculation algorithm (Homogeneous, Batho, ETAR). The dose comparisons were described in terms of 2D isodose distribution, percent depth dose data, effective path length and monitor unit. Also dose distributions were calculated with homogeneous and inhomogeneous correction algorithm, Batho and ETAR, in each patients with different clinical sites. Result indicated that Batho and ETAR method gave rise to percent depth dose deviation 1.5-2.7%, 2.3-3.5% (6 MV, field size 10 x 10 cm2) in each status with and without contrast medium. Also show that effective path lengths were more increase in contrast status (23.14 cm) than Non-contrast (22.07 cm) about 4.9% or 10.7 mm (In case Hounsfield Unit 270) and these results were similarly showed in each patient with different clinical site that was lung, prostate, liver and brain region. In conclusion we shown that the use of inhomogeneity correction algorithm for dose calculation in status of injected contrast medium can not represent exact dose at GTV region. These results mean that patients will be more irradiated photon beam during radiation therapy.
Internal Dose Calculations with the New Biokinetic Models of the ICRP
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Silverman, I.; Shamai, Y.; Schlesinger, T.; Biran, T
1999-07-01
During the past decade, the ICRP made major revisions in its recommendations regarding protection from ionising radiation and advised the use of new models for estimating doses due to intake of radionuclides. A new Internal Dosimetry code (InDose) is presented which employs all the new biokinetic models together with the new respiratory tract (RT) model and the gastrointestinal tract (GI) model. The code makes use of a generalised form of these new biokinetic models which enables the use of any of them. The code has been used to assess intakes and doses for the 3rd European Intercomparison Exercise on Internal Dose Assessment. A detailed study of one of the test cases of this exercise is presented. Our code using the new plutonium biokinetic model and LUDEP gave similar results. InDose, however, provides a way to insert consistent changes in the models in orderto make estimations under non-standard conditions. The new biokinetic model has been found to give better agreement with measured data than the old (ICRP 30) model. (author)
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In this work the implementation of a modification of the VARSKIN code for calculation of absorbed dose for contamination in skin imparted by external radiation fields generated by Beta emitting is presented. The modification consists on the inclusion of 47 isotopes of interest even Nuclear Plants for the dose evaluation in skin generated by 'hot particles'. The approach for to add these isotopes is the correlation parameter F and the average energy of the Beta particle, with relationship to those 75 isotopes of the original code. The methodology of the dose calculation of the VARSKIN code is based on the interpolation, (and integration of the interest geometries: punctual or plane sources), of the distribution functions scaled doses in water for beta and electrons punctual sources, tabulated by Berger. Finally a brief discussion of the results for their interpretation and use with purposes of radiological protection (dose insurance in relation to the considered biological effects) is presented
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Herraiz Lblanca, M. D.; Diaz Romero, F.; Casares Magaz, O.; Garrido Breton, C.; Catalan Acosta, A.; Hernandez Armas, J.
2013-07-01
This paper proposes a method that allows you to calculate the effective dose in any interventional radiology procedure using an anthropomorphic mannequin Alderson RANDO and dosimeters TLD 100 chip. This method has been applied to an angio Radiology procedure: the biliary drainage. The objectives that have been proposed are: to) put together a method that, on an experimental basis, allows to know dosis en organs to calculate effective dose in complex procedures and b) apply the method to the calculation of the effective dose of biliary drainage. (Author)
A Comparison of Model Calculation and Measurement of Absorbed Dose for Proton Irradiation. Chapter 5
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.
A 3D pencil-beam-based superposition algorithm for photon dose calculation in heterogeneous media
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.
GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources
Townson, Reid; Tian, Zhen; Graves, Yan Jiang; Zavgorodni, Sergei; Jiang, Steve B
2013-01-01
A novel phase-space source implementation has been designed for GPU-based Monte Carlo dose calculation engines. 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 strategy to pre-process patient-independent phase-spaces and bin particles by type, energy and position. Position bins l...
A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phantom
International Nuclear Information System (INIS)
As the most accurate method to estimate absorbed dose in radiotherapy, Monte Carlo method has been widely used in radiotherapy treatment planning. Nevertheless, its efficiency can be improved for clinical routine applications. In this paper, we present the CUBMC code, a GPU-based Mc photon transport algorithm for dose calculation under the Compute Unified Device Architecture platform. The simulation of physical events is based on the algorithm used in Penelope, and the cross section table used is the one generated by the Material routine, als present in Penelope code. Photons are transported in voxel-based geometries with different compositions. To demonstrate the capabilities of the algorithm developed in the present work four 128 x 128 x 128 voxel phantoms have been considered. One of them is composed by a homogeneous water-based media, the second is composed by bone, the third is composed by lung and the fourth is composed by a heterogeneous bone and vacuum geometry. Simulations were done considering a 6 MeV monoenergetic photon point source. There are two distinct approaches that were used for transport simulation. The first of them forces the photon to stop at every voxel frontier, the second one is the Woodcock method, where the photon stop in the frontier will be considered depending on the material changing across the photon travel line. Dose calculations using these methods are compared for validation with Penelope and MCNP5 codes. Speed-up factors are compared using a NVidia GTX 560-Ti GPU card against a 2.27 GHz Intel Xeon CPU processor. (Author)
A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phantom
Energy Technology Data Exchange (ETDEWEB)
Bellezzo, M.; Do Nascimento, E.; Yoriyaz, H., E-mail: mbellezzo@gmail.br [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)
2014-08-15
As the most accurate method to estimate absorbed dose in radiotherapy, Monte Carlo method has been widely used in radiotherapy treatment planning. Nevertheless, its efficiency can be improved for clinical routine applications. In this paper, we present the CUBMC code, a GPU-based Mc photon transport algorithm for dose calculation under the Compute Unified Device Architecture platform. The simulation of physical events is based on the algorithm used in Penelope, and the cross section table used is the one generated by the Material routine, als present in Penelope code. Photons are transported in voxel-based geometries with different compositions. To demonstrate the capabilities of the algorithm developed in the present work four 128 x 128 x 128 voxel phantoms have been considered. One of them is composed by a homogeneous water-based media, the second is composed by bone, the third is composed by lung and the fourth is composed by a heterogeneous bone and vacuum geometry. Simulations were done considering a 6 MeV monoenergetic photon point source. There are two distinct approaches that were used for transport simulation. The first of them forces the photon to stop at every voxel frontier, the second one is the Woodcock method, where the photon stop in the frontier will be considered depending on the material changing across the photon travel line. Dose calculations using these methods are compared for validation with Penelope and MCNP5 codes. Speed-up factors are compared using a NVidia GTX 560-Ti GPU card against a 2.27 GHz Intel Xeon CPU processor. (Author)
SU-E-T-386: A Monte Carlo Dose Calculation Framework for Electron Beams On Varian TrueBeam
International Nuclear Information System (INIS)
Purpose: The design of the linac head is different for TrueBeam than Clinac, and there are differences in measured dose distributions in water phantoms between TrueBeam and Clinac for electron beams. Therefore, MC models for Clinac may not be applied directly to the Truebeam linac. The purpose of this study is to validate a Monte Carlo (MC) dose calculation framework for electron beams on Varian TrueBeam with phase space files provided by Varian. Methods: The particle histories from the phase space file were used as input for the down-stream simulation including jaws, applicators, and water phantom. MC packages BEAMnrc/DOSYXZnrc were used. The down-stream beam components were modeled according to manufacturer specifications and the dose distributions were compared with the measured data of standard cones. The measurements were performed in a water phantom with a p-type electron field diode (diameter 0.2cm) and ion chamber (CC13). Depth dose and orthogonal profiles at depths defined by R1 0 0, R5 0, Rp were compared. Results: Preliminary results for a 16 MeV phase space and 10x10, 15x15, and 20x20 cm2 applicator are presented. Simulations were run for a statistical uncertainty of <2% at depth of maximum dose for a voxel resolution of 0.5x0.5x0.2cm2. Dose and range differences for the PDD profiles were within 2% and 1 mm, respectively. Dose differences within the central 80% of the beam width for the orthogonal profiles at depth of maximum dose were less than 2% for the 10x10, 15x15, and 20x20 cm2 applicator, respectively. Conclusion: Varian electron phase space files simulations are in agreement with measured commissioning data. These phase space files can be used in the simulation of TrueBeam linacs, and will provide reproducibility across publications. Analyses for all electron energies and standard applicators are under way and results will be included in the presentation
Inoue, R; Hiraga, F; Kiyanagi, Y
2014-06-01
An accelerator based BNCT has been desired because of its therapeutic convenience. However, optimal design of a neutron moderator system is still one of the issues. Therefore, detailed studies on materials consisting of the moderator system are necessary to obtain the optimal condition. In this study, the epithermal neutron flux and the RBE dose have been calculated as the indicators to look for optimal materials for the filter and the moderator. As a result, it was found that a combination of MgF2 moderator with Fe filter gave best performance, and the moderator system gave a dose ratio greater than 3 and an epithermal neutron flux over 1.0×10(9)cm(-2)s(-1).
Energy Technology Data Exchange (ETDEWEB)
Fillion, O; Gingras, L [Departement de radiooncologie, CHU de Quebec - Hotel-Dieu de Quebec, Quebec, Quebec (Canada); Departement de physique, de genie physique et d' optique, Universite Laval, Quebec, Quebec (Canada); Archambault, L [Departement de radiooncologie, CHU de Quebec - Hotel-Dieu de Quebec, Quebec, Quebec (Canada); Departement de physique, de genie physique et d' optique, Universite Laval, Quebec, Quebec (Canada); Centre de recherche sur le cancer, Universite Laval, Quebec, Quebec (Canada)
2014-06-15
Purpose: Artifacts can reduce the quality of dose re-calculations on CBCT scans during a treatment. The aim of this project is to correct the CBCT images in order to allow for more accurate and exact dose calculations in the case of a translation of the tumor in prostate cancer. Methods: Our approach is to develop strategies based on deformable image registration algorithms using the elastix software (Klein et al., 2010) to register the treatment planning CT on a daily CBCT scan taken during treatment. Sets of images are provided by a 3D deformable phantom and comprise two CT and two CBCT scans: one of both with the reference anatomy and the others with known deformations (i.e. translations of the prostate). The reference CT is registered onto the deformed CBCT and the deformed CT serves as the control for dose calculation accuracy. The planned treatment used for the evaluation of dose calculation is a 2-Gy fraction prescribed at the location of the reference prostate and assigned to 7 rectangular fields. Results: For a realistic 0.5-cm translation of the prostate, the relative dose discrepancy between the CBCT and the CT control scan at the prostate's centroid is 8.9 ± 0.8 % while dose discrepancy between the registered CT and the control scan lessens to −2.4 ± 0.8 %. For a 2-cm translation, clinical indices like the V90 and the D100 are more accurate by 0.7 ± 0.3 % and 8.0 ± 0.5 cGy respectively when using registered CT than when using CBCT for dose calculation. Conclusion: The results show that this strategy gives doses in agreement within a few percents with those from calculations on actual CT scans. In the future, various deformations of the phantom anatomy will allow a thorough characterization of the registration strategies needed for more complex anatomies.
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.
Pietrzak, Robert; Konefał, Adam; Sokół, Maria; Orlef, Andrzej
2016-08-01
The success of proton therapy depends strongly on the precision of treatment planning. Dose distribution in biological tissue may be obtained from Monte Carlo simulations using various scientific codes making it possible to perform very accurate calculations. However, there are many factors affecting the accuracy of modeling. One of them is a structure of objects called bins registering a dose. In this work the influence of bin structure on the dose distributions was examined. The MCNPX code calculations of Bragg curve for the 60 MeV proton beam were done in two ways: using simple logical detectors being the volumes determined in water, and using a precise model of ionization chamber used in clinical dosimetry. The results of the simulations were verified experimentally in the water phantom with Marcus ionization chamber. The average local dose difference between the measured relative doses in the water phantom and those calculated by means of the logical detectors was 1.4% at first 25 mm, whereas in the full depth range this difference was 1.6% for the maximum uncertainty in the calculations less than 2.4% and for the maximum measuring error of 1%. In case of the relative doses calculated with the use of the ionization chamber model this average difference was somewhat greater, being 2.3% at depths up to 25 mm and 2.4% in the full range of depths for the maximum uncertainty in the calculations of 3%. In the dose calculations the ionization chamber model does not offer any additional advantages over the logical detectors. The results provided by both models are similar and in good agreement with the measurements, however, the logical detector approach is a more time-effective method.
Mairani, A; Valente, M; Battistoni, G; Botta, F; Pedroli, G; Ferrari, A; Cremonesi, M; Di Dia, A; Ferrari, M; Fasso, A
2011-01-01
Purpose: The calculation of patient-specific dose distribution can be achieved by Monte Carlo simulations or by analytical methods. In this study, FLUKA Monte Carlo code has been considered for use in nuclear medicine dosimetry. Up to now, FLUKA has mainly been dedicated to other fields, namely high energy physics, radiation protection, and hadrontherapy. When first employing a Monte Carlo code for nuclear medicine dosimetry, its results concerning electron transport at energies typical of nuclear medicine applications need to be verified. This is commonly achieved by means of calculation of a representative parameter and comparison with reference data. Dose point kernel (DPK), quantifying the energy deposition all around a point isotropic source, is often the one. Methods: FLUKA DPKS have been calculated in both water and compact bone for monoenergetic electrons (10-3 MeV) and for beta emitting isotopes commonly used for therapy ((89)Sr, (90)Y, (131)I, (153)Sm, (177)Lu, (186)Re, and (188)Re). Point isotropic...
Energy Technology Data Exchange (ETDEWEB)
None
1978-06-01
A companion report, DOE/ET-0064/1, presents a geographic, cultural, and demographic profile of the Tennessee Valley Region study area. This report describes the calculations of radionuclide release and transport and of the resultant dose to the regional population, assuming a projected installed capacity of 220,000 MW in the year 2000, of which 144,000 MW would be nuclear. All elements of the fuel cycle were assumed to be in operation. The radiological dose was calculated as a one-year dose based on ingestion of 35 different food types as well as for nine non-food pathways, and was reported as dose to the total body and for six specific organs for each of four age groups (infant, child, teen, and adult). Results indicate that the average individual would receive an incremental dose of 7 x 10/sup -4/ millirems in the year 2000 from the operation of nuclear facilities within and adjacent to the region, five orders of magnitude smaller than the dose from naturally occurring radiation in the area. The major contributor to dose was found to be tritium, and the most significant pathways were immersion in air, inhalation of air, transpiration of tritium (absorption through the skin), and exposure radionuclide-containing soil. 60 references.
Held, Mareike; Sneed, Penny K; Fogh, Shannon E; Pouliot, Jean; Morin, Olivier
2015-01-01
Unlike scheduled radiotherapy treatments, treatment planning time and resources are limited for emergency treatments. Consequently, plans are often simple 2D image-based treatments that lag behind technical capabilities available for nonurgent radiotherapy. We have developed a novel integrated urgent workflow that uses onboard MV CBCT imaging for patient simulation to improve planning accuracy and reduce the total time for urgent treatments. This study evaluates both MV CBCT dose planning accuracy and novel urgent workflow feasibility for a variety of anatomic sites. We sought to limit local mean dose differences to less than 5% compared to conventional CT simulation. To improve dose calculation accuracy, we created separate Hounsfield unit-to-density calibration curves for regular and extended field-of-view (FOV) MV CBCTs. We evaluated dose calculation accuracy on phantoms and four clinical anatomical sites (brain, thorax/spine, pelvis, and extremities). Plans were created for each case and dose was calculated on both the CT and MV CBCT. All steps (simulation, planning, setup verification, QA, and dose delivery) were performed in one 30 min session using phantoms. The monitor units (MU) for each plan were compared and dose distribution agreement was evaluated using mean dose difference over the entire volume and gamma index on the central 2D axial plane. All whole-brain dose distributions gave gamma passing rates higher than 95% for 2%/2 mm criteria, and pelvic sites ranged between 90% and 98% for 3%/3 mm criteria. However, thoracic spine treatments produced gamma passing rates as low as 47% for 3%/3 mm criteria. Our novel MV CBCT-based dose planning and delivery approach was feasible and time-efficient for the majority of cases. Limited MV CBCT FOV precluded workflow use for pelvic sites of larger patients and resulted in image clearance issues when tumor position was far off midline. The agreement of calculated MU on CT and MV CBCT was acceptable for all
Nedaie, Hassan Ali; Darestani, Hoda; Banaee, Nooshin; Shagholi, Negin; Mohammadi, Kheirollah; Shahvar, Arjang; Bayat, Esmaeel
2014-01-01
High-energy linacs produce secondary particles such as neutrons (photoneutron production). The neutrons have the important role during treatment with high energy photons in terms of protection and dose escalation. In this work, neutron dose equivalents of 18 MV Varian and Elekta accelerators are measured by thermoluminescent dosimeter (TLD) 600 and TLD700 detectors and compared with the Monte Carlo calculations. For neutron and photon dose discrimination, first TLDs were calibrated separately...
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.
Numerical calculations of high-altitude differential charging: Preliminary results
Laframboise, J. G.; Godard, R.; Prokopenko, S. M. L.
1979-01-01
A two dimensional simulation program was constructed in order to obtain theoretical predictions of floating potential distributions on geostationary spacecraft. The geometry was infinite-cylindrical with angle dependence. Effects of finite spacecraft length on sheath potential profiles can be included in an approximate way. The program can treat either steady-state conditions or slowly time-varying situations, involving external time scales much larger than particle transit times. Approximate, locally dependent expressions were used to provide space charge, density profiles, but numerical orbit-following is used to calculate surface currents. Ambient velocity distributions were assumed to be isotropic, beam-like, or some superposition of these.
Radiotherapy dose calculation on KV cone-beam CT image for lung tumor using the CIRS calibration
Ma, ChangSheng; Cao, Jianping; Yin, Yong; Zhu, Jian
2014-01-01
On-board kilovoltage (KV) cone-beam computed tomography (CBCT) images are used predominantly for the setup of patients' positioning. The image data can also potentially be used for dose calculation with the precise calibration of Hounsfield units (HU) to electron density (HU-density). CBCT calibration was analyzed in this study. A clinical treatment planning system was employed for CT and KV CBCT image to dose calculations and subsequent comparisons. Two HU-density tables were generated using...
International Nuclear Information System (INIS)
Reconstruction of internal dose for various populations has been conducted in Russia following past major environmental radionuclide releases resulting from operation of and emergencies at Mayak PA facility in Urals in 1950s, nuclear weapons tests at Semipalatinsk test site since 1949, and the Chernobyl accident in 1986. The objectives of those activities usually were radiation risk assessment and/or support of radiation and social protection programs and of epidemiological studies. The Russian internal thyroid dose reconstruction program that is the closest to the Fukushima program under development was the Chernobyl study for populations of the more affected areas. Radiation monitoring conducted in the affected areas included measurements of both environmental and food samples and human thyroid. The dose reconstruction procedure for various areas was structured according to availability of monitoring data. The paper presents general methodology for reconstruction of the internal dose in groups of inhabitants of the Chernobyl accident area and practical techniques for reconstruction of the 131I absorbed dose in thyroid. The techniques are based on the results of radiation monitoring performed in 1986 in the Bryansk, Tula, Orel and Kaluga regions of Russia. The 131I measurements of the thyroid as the data most relevant to internal dose are of first priority for dose reconstruction. Radionuclide intake estimation with foods is considered as the second priority and application of radioecological models as the third priority when measurement data are lacking. The developed internal thyroid dose reconstruction algorithms were converted in the official national methodology that was used for large scale reconstruction of average internal thyroid dose in more than four thousand Russian settlements affected by the Chernobyl fallout. The results were used both for decision making regarding radiation and social protection of the public and as support for epidemiological
Energy Technology Data Exchange (ETDEWEB)
Landsman, S.D.; Thornhill, R.E.; Peterson, C.A.
1996-04-01
In this report, the dose estimate for CY 1995 is reconciled by month wih actual doses received. Results of the reconciliation were used to revise estimates of worker dose for CY 1996. Resulting dose estimate for the facility is also included. Support for two major programs (B-Cell Cleanout and Surveillance and Maintenance) accounts for most of the exposure received by workers in the faility. Most of the expousre received by workers comes from work in the Radiochemical Engineering Complex airlock. In spite of schedule and work scope changes during CY 1995, dose estimates were close to actual exposures received. A number of ALARA measures were taken throughout the year; exposure reduction due to those was 20.6 Man-Rem, a 28% reduction from the CY 1995 estimate. Baseline estimates for various tasks in the facility were used to compile the CY 1996 dose estimate of 45.4 Man-Rem; facility goal for CY 1996 is to reduce worker dose by 20%, to 36.3 Man-Rem.
International Nuclear Information System (INIS)
Purpose: To provide commissioning and acceptance test data of the Varian Eclipse electron Monte Carlo model (eMC v.11) for TrueBeam linac. We also investigated the uncertainties in beam model parameters and dose calculation results for different geometric configurations. Methods: For beam commissioning, PTW CC13 thimble chamber and IBA Blue Phantom2 were used to collect PDD and dose profiles in air. Cone factors were measured with a parallel plate chamber (PTW N23342) in solid water. GafChromic EBT3 films were used for dose calculation verifications to compare with parallel plate chamber results in the following test geometries: oblique incident, extended distance, small cutouts, elongated cutouts, irregular surface, and heterogeneous layers. Results: Four electron energies (6e, 9e, 12e, and 15e) and five cones (6×6, 10×10, 15×15, 20×20, and 25×25) with standard cutouts were calculated for different grid sizes (1, 1.5,2, and 2.5 mm) and compared with chamber measurements. The results showed calculations performed with a coarse grid size underestimated the absolute dose. The underestimation decreased as energy increased. For 6e, the underestimation (max 3.3 %) was greater than the statistical uncertainty level (3%) and was systematically observed for all cone sizes. By using a 1mm grid size, all the calculation results agreed with measurements within 5% for all test configurations. The calculations took 21s and 46s for 6e and 15e (2.5mm grid size) respectively distributed on 4 calculation servants. Conclusion: In general, commissioning the eMC dose calculation model on TrueBeam is straightforward and thedose calculation is in good agreement with measurements for all test cases. Monte Carlo dose calculation provides more accurate results which improves treatment planning quality. However, the normal acceptable grid size (2.5mm) would cause systematic underestimation in absolute dose calculation for lower energies, such as 6e. Users need to be cautious in this
Energy Technology Data Exchange (ETDEWEB)
Hardiansyah, D.; Haryanto, F. [Nuclear Physics and Biophysics Research Laboratory, Physics Department, Institut Teknologi Bandung (ITB) (Indonesia); Male, S. [Radiotherapy Division, Research Hospital of Hassanudin University (Indonesia)
2014-09-30
Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (R{sub p}) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue.
Hardiansyah, D.; Male, S.; Haryanto, F.
2014-09-01
Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (Rp) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue.
International Nuclear Information System (INIS)
Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (Rp) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue
International Nuclear Information System (INIS)
To investigate the effect of computed tomography (CT) using hepatic arterial phase (HAP) and portal venous phase (PVP) contrast on dose calculation of stereotactic body radiation therapy (SBRT) for liver cancer. Twenty-one patients with liver cancer were studied. HAP, PVP and non-enhanced CTs were performed on subjects scanned in identical positions under active breathing control (ABC). SBRT plans were generated using seven-field three-dimensional conformal radiotherapy (7 F-3D-CRT), seven-field intensity-modulated radiotherapy (7 F-IMRT) and single-arc volumetric modulated arc therapy (VMAT) based on the PVP CT. Plans were copied to the HAP and non-enhanced CTs. Radiation doses calculated from the three phases of CTs were compared with respect to the planning target volume (PTV) and the organs at risk (OAR) using the Friedman test and the Wilcoxon signed ranks test. SBRT plans calculated from either PVP or HAP CT, including 3D-CRT, IMRT and VMAT plans, demonstrated significantly lower (p <0.05) minimum absorbed doses covering 98%, 95%, 50% and 2% of PTV (D98%, D95%, D50% and D2%) than those calculated from non-enhanced CT. The mean differences between PVP or HAP CT and non-enhanced CT were less than 2% and 1% respectively. All mean dose differences between the three phases of CTs for OARs were less than 2%. Our data indicate that though the differences in dose calculation between contrast phases are not clinically relevant, dose underestimation (IE, delivery of higher-than-intended doses) resulting from CT using PVP contrast is larger than that resulting from CT using HAP contrast when compared against doses based upon non-contrast CT in SBRT treatment of liver cancer using VMAT, IMRT or 3D-CRT
International Nuclear Information System (INIS)
Problem of formation doses are considered at the peroral entering of 137Cs in the organism of laboratory rats. First the functions of isotopes retention and values of biokinetic constants have been determined for different organs and tissues. Multicamerate model for description of biokinetics of radionuclides in the organism is proposed. Advantages of application of this model for estimation of absorbed doses are discussed in comparison to existent models
Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections
Jones, Bernard L; Miften, Moyed
2015-01-01
Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. We 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. Resu...
The ICRP opinion of the calculation of doses and risks associated with exposures to tritium
International Nuclear Information System (INIS)
As the management of exposures to tritium, just like for other radionuclides, relies on the effective dose calculation, it also requires the application of coefficients to take the variety of radiations and the sensitivity of the different irradiated tissues into account. The authors discuss the determination and the use of the weighting factor (Wr) which reflects the relative biological effectiveness (RBE) of different types of radiation. They outline that some researchers asked for a review of this factor, and that the RBE is related to several parameters. All this and other issues entail uncertainties. The authors then give the opinion of the ICRP on this issue and notably for the assessment of the individual risk of cancer after exposure to tritium
International Nuclear Information System (INIS)
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
Lens of the eye dose calculation for neuro-interventional procedures and CBCT scans of the head
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 thi